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United States Patent Application	20090152162
Kind Code	A1
TIAN; LU ;   et al.	June 18, 2009

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Claims

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1. A carrier apparatus for holding a shaped sheet material, the apparatus comprising:a first frame structure having a first front surface including a first outer peripheral region and a first inner peripheral region separated by a first step, the first inner peripheral region being characterized by a width of a ledge extended circumferentially from the first step and one or more athwart dimensions from the first step at one side of the first inner peripheral region to the first step at an opposing side of the first inner peripheral region in one or more diagonal orientations;a second frame structure having a second front surface including a second outer peripheral region and a second inner peripheral region separated by a second step, the second front surface being configured to engage with the first front surface at a close position so that the second outer peripheral region is at least partially in contact with the first outer peripheral region and the second step circumferentially mates the first step with the second inner peripheral region opposing to the first inner peripheral region by a gap;one or more locking mechanisms to withhold the second frame structure engaged with the first frame structure; anda shaped wing structure integrally extended from outer peripheral edge of the first frame structure.

2. The carrier apparatus of claim 1 wherein the first step moves down from the first outer peripheral region to the first inner peripheral region as the first front surface faces up and the second step moves up from the second outer peripheral region to the second inner peripheral region as the second front surface faces up.

3. The carrier apparatus of claim 2 wherein the first step is associated with a first step height and the second step is associated with a second step height, the second step height is smaller than the first step height.

4. The carrier apparatus of claim 3 wherein a difference between the first step height and the second step height in the close position with the second inner peripheral region opposing the first inner peripheral region is substantially equal to the gap.

5. The carrier apparatus of claim 4 wherein the gap is bigger than a thickness of the shaped sheet material by a predetermined margin.

6. The carrier apparatus of claim 5 wherein the thickness of the shaped sheet material comprises a range from 10 .mu.m to 200 .mu.m.

7. The carrier apparatus of claim 1 wherein the one or more athwart dimensions from the first step at one side of the first inner peripheral region to the first step at an opposing side of the first inner peripheral region in one or more diagonal orientations are configured to be substantially equal to or bigger than one or more lateral dimensions of the shaped sheet material so that the shaped sheet material can be circumferentially enclosed within the first step with at least one or more peripheral portions of the shaped sheet material being partially supported by the width of the ledge of the first inner peripheral region.

8. The carrier apparatus of claim 7 wherein the width of the ledge of the first inner peripheral region comprises a distance in certain orientation equal to about 5% of an athwart dimension in that orientation.

9. The carrier apparatus of claim 7 wherein the one or more athwart dimensions comprise about 50 millimeters or greater, or 100 millimeters or bigger, or about 125 millimeters or bigger, or about 156 millimeters or bigger.

10. The carrier apparatus of claim 1 wherein the one or more locking mechanisms comprise one or more screws at predetermined corner locations, or one or more clips at predetermined locations of the first outer peripheral region and the second outer peripheral region, or one or more combinations of hinges and latches at predetermined locations of the first outer peripheral region and the second outer peripheral region.

11. The carrier apparatus of claim 1 wherein the shaped wing structure integrally extended from a periphery of the first frame structure comprises a substantially rounded shape with a diameter ranging from 4 inches to 12 inches and a thickness of about 1 millimeter or smaller.

12. The carrier apparatus of claim 1 wherein the first frame structure and the second frame structure are made of a material selected from Teflon, PVDF (Polyvinylidene Difluoride), PEEK (Polyetheretherketones), PET (polyethylene terephthalate), polyimide, quartz, and aluminum, molybdenum, anodized aluminum, stainless steel, and metal alloy comprising nickel, molybdenum, chromium, cobalt, iron, copper, manganese, titanium, zirconium, aluminum, carbon, and tungsten.

13. The carrier apparatus of claim 1, and further comprises a first cover circumferentially coupled to the first inner peripheral region and a second cover circumferentially coupled to the second inner peripheral region.

14. A carrier apparatus for holding a shaped sheet material, the apparatus comprising:a first C-like frame member including two first arm sections each with a first length from a first base to a first end integrally extended from a first middle section, the two first arm sections each including two side-ridges with substantially first half of the first length from the first end, a middle slot formed between the two side ridges, and a middle hole extended further from the middle slot with a same lateral dimension and substantially second half of the first length;a second C-like frame member including two second arm sections each with a second length from a second base to a second end integrally extended from a second middle section, the two second arm sections each including a middle rod with substantially first half of the second length from the second end and two side slots further extended substantially second half the second length, the second length being substantially equal to the first length, the middle rod being configured to slidingly mate with the middle slot and further with the middle hole till a close position as the two side slots fully engage with the two side-ridges;a first trench formed through a first inner side of the first C-like frame member with a predetermined depth, the first trench being offset the middle hole and two side ridges; anda second trench formed through a second inner side of the second C-like frame member with substantially the same predetermined depth, the second trench and the first trench being connected at the close position.

15. The carrier apparatus of claim 14, and further comprising a shaped wing structure extended from outer peripheral edges of both the first C-like frame member and the second C-like frame member.

16. A carrier cassette for a plurality of carrier apparatus, the carrier cassette comprising:a length of a bulk structure with a U-like cross section including a bottom surface and an inner surface, the inner surface including a plurality of slots disposed perpendicular to the length of the bulk structure with a predetermined spacing between each other, each of the plurality of slots being configured to be inserted with a carrier apparatus, the carrier apparatus comprising:a first frame structure having a first front surface including a first outer peripheral region and a first inner peripheral region separated by a first step, the first inner peripheral region being characterized by a width of a ledge extended circumferentially from the first step and one or more athwart dimensions from the first step at one side of the first inner peripheral region to the first step at an opposing side of the first inner peripheral region in one or more diagonal orientations;a second frame structure having a second front surface including a second outer peripheral region and a second inner peripheral region separated by a second step, the second front surface being configured to engage with the first front surface at a close position so that the second outer peripheral region is at least partially in contact with the first outer peripheral region and the second step circumferentially mates the first step with the second inner peripheral region opposing to the first inner peripheral region by a gap;one or more locking mechanisms to secure the second frame structure engaged with the first frame structure; anda shaped wing structure integrally extended from outer peripheral edge of the first frame structure;one or more holes disposed at the bottom portion of each of the plurality of slots penetrating through the bottom surface.

17. A method for handling a shaped sheet material, the method comprising:providing a shaped sheet material characterized by one or more lateral dimensions and a thickness;providing a carrier apparatus adapted to the shaped sheet material based on at least information of the one or more lateral dimensions and the thickness, the carrier apparatus comprising:a first frame structure having a first front surface including a first outer peripheral region and a first inner peripheral region separated by a first step, the first inner peripheral region being characterized by a width of a ledge extended circumferentially from the first step and one or more athwart dimensions from the first step at one side of the first inner peripheral region to the first step at an opposing side of the first inner peripheral region in one or more diagonal orientations; p2 a second frame structure having a second front surface including a second outer peripheral region and a second inner peripheral region separated by a second step, the second front surface being configured to engage with the first front surface at a close position so that the second outer peripheral region is at least partially in contact with the first outer peripheral region and the second step circumferentially mates the first step with the second inner peripheral region opposing to the first inner peripheral region by a gap;one or more locking mechanisms to withhold the second frame structure engaged with the first frame structure; anda shaped wing structure integrally extended from outer peripheral edge of the first frame structure;exposing the first front surface;loading the shaped sheet material onto the first inner peripheral region;disposing the second frame structure to mate the first frame structure so that the second front surface engages with the first front surface at the close position of the carrier apparatus;securing the engaged first frame structure and the second frame structure; andtransferring the carrier apparatus to process the shaped sheet material held therein.

18. The method of claim 17 wherein the shaped sheet material comprises a deformable thin wafer produced by cleaving a bulk material including ingots of single-crystalline or polycrystalline silicon, or germanium, or III/V group compound semiconductor.

19. The method of claim 17 wherein the one or more lateral dimensions of the shaped deformable sheet material comprises about 50 mm or bigger, or 100 mm or bigger, or about 125 mm or bigger, or about 156 mm or bigger.

20. The method of claim 17 wherein the thickness of the shaped deformable sheet material comprises a range from 10 .mu.m to 200 .mu.m.

21. The method of claim 17 wherein providing a carrier apparatus for the shaped sheet material comprises determining the first frame structure and the second frame structure adaptive to the shaped sheet material based on at least the one or more lateral dimensions and the thickness.

22. The method of claim 17 wherein loading the shaped sheet material can be performed by an electrostatic chuck or a vacuum chuck.

23. The method of claim 17 wherein securing the engaged first frame structure and the second frame structure comprises utilizing the one or more locking mechanisms including one or more clips, or one or more screws, or one or more springs, or one or more latches.

24. The method of claim 17 wherein transferring the carrier apparatus to process the shaped sheet material held therein comprises loading a plurality of carrier apparatuses, each holding a shaped sheet material, respectively into a carrier cassette including a plurality of slots with a width matched the shaped wing structure and inter-slot spacing adapted to a total thickness of the carrier apparatus; transferring the carrier cassette including the plurality of carrier apparatuses into a processing system; and simultaneously processing both sides of each shaped sheet material held within each carrier.

25. The method of claim 24 wherein simultaneously processing both sides of each shaped sheet material held within each carrier comprises performing a wet cleaning process, or a chemical etching process, or a deposition process, or a thermal annealing process, or a material characterization process.

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Description

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CROSS-REFERENCES TO RELATED APPLICATIONS

[0001]Not applicable

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002]Not applicable

REFERENCE TO A "SEQUENCE LISTING," A TABLE, OR A COMPUTER PROGRAM LISTING APPENDIX SUBMITTED ON A COMPACT DISK

[0003]Not applicable

BACKGROUND OF THE INVENTION

[0004]The present invention relates generally to technique for handling shaped sheet materials. More particularly, the present invention provides a carrier apparatus including a top frame structure and a bottom frame structure configured to be engaged with each other and method of using the carrier apparatus for holding a shaped sheet material to perform any process or storage. Merely by way of example, the invention has been applied for handling deformable silicon sheets or thin wafers of 10 to 200 microns in thickness and 50 millimeters and greater in lateral dimension produced by a layer transfer technique based on RFQ linear accelerator system and used for a variety of applications including photovoltaic cells. But it will be recognized that the invention has a wider range of applicability.

[0005]From the beginning of time, human beings have relied upon the "sun" to derive almost all useful forms of energy. Such energy comes from petroleum, radiant, wood, and various forms of thermal energy. As merely an example, human being have relied heavily upon petroleum sources such as coal and gas for much of their needs. Unfortunately, such petroleum sources have become depleted and have lead to other problems. As a replacement, in part, solar energy has been proposed to reduce our reliance on petroleum sources. As merely an example, solar energy can be derived from "solar cells" commonly made of silicon.

[0006]The silicon solar cell generates electrical power when exposed to solar radiation from the sun. The radiation interacts with atoms of the silicon and forms electrons and holes that migrate to p-doped and n-doped regions in the silicon body and create voltage differentials and an electric current between the doped regions. Depending upon the application, solar cells have been integrated with concentrating elements to improve efficiency. As an example, solar radiation accumulates and focuses using concentrating elements that direct such radiation to one or more portions of active photovoltaic materials. Although effective, these solar cells still have many limitations.

[0007]As merely an example, solar cells rely upon starting materials such as silicon. Such silicon is often made using either polysilicon (i.e. polycrystalline silicon) and/or single crystal silicon materials. These materials are often difficult to manufacture. Polysilicon cells are often formed by manufacturing polysilicon plates. Although these plates may be formed effectively, they do not possess optimum properties for highly effective solar cells. Single crystal silicon has suitable properties for high grade solar cells. Such single crystal silicon is, however, expensive and is also difficult to use for solar applications in an efficient and cost effective manner. Additionally, both polysilicon and single-crystal silicon materials suffer from material losses during conventional manufacturing called "kerf loss", where the sawing process used for cutting the plates with thickness ranging from 10 .mu.m to 200 .mu.m from bulk materials eliminates as much as 40% and even up to 60% of the starting material from a cast or grown boule and singulate the material into a wafer form factor. This is a highly inefficient method of preparing thin polysilicon or single-crystal silicon plates for solar cell use.

[0008]Numerous drawbacks of the conventional sawing process can be overcome using a novel layer transfer technique based on a cost effective linear accelerator system to perform a high energy ion-beam implantation process for producing transferable sheet materials or thin wafers. For example, the layer transfer technique in association with a linear accelerator system has been described in a co-assigned U.S. patent application Ser. No. 11/935,197 by Francois J Henley et al., and titled "METHOD AND STRUCTURE FOR THICK LAYER TRANSFER USING A LINEAR ACCELERATOR", filed on Nov. 5, 2007. The deformable sheet materials made from bulk semiconductors may be further processed for applications such as photovoltaic devices, 3D MEMS or integrated circuits, IC packaging, semiconductor devices, silicon carbide and gallium nitride films for semiconductor and optoelectronic applications, any combination of these, and others. In particular, single crystal silicon sheets or thin wafers for highly efficient photovoltaic cells can be formed very cost-effectively with the desired form factor (for example, 10 .mu.m-200 .mu.m thickness with a area size from 10 cm.times.10 cm to upwards of 1 m.times.1 m or more for polysilicon films/plates). Merely as an example, these silicon sheets can be formed from a single ingot, e.g., silicon boule and repeated to successively cleave one slice after another (similar to cutting slices of bread from a baked loaf) according to a specific embodiment. Because of the relative thin thickness (200 microns or less) of these sheet materials, they are substantially deformable especially when the lateral dimension becomes 50 mm or larger. Therefore, traditional wafer carrier/cassette does not suit for holding such deformable sheet materials. The state-of-art technique for handling such thin silicon wafers may rely on using an electrostatic chuck or a vacuum chuck which clamps at least one side of the wafer by electrostatic force or pressure force. However, a slight malfunction of chucking and dechucking sequences may changes the forces that are not delicate enough to avoid damages to these deformable silicon sheets or thin wafers. Additionally, the usage of chucking method requires substantial contact of at least one side the sheet or thin wafer. This also causes easy contamination and inconvenience for cleaning and other processing. Accordingly a carrier apparatus and method for holding the deformable sheet materials are highly desired.

SUMMARY OF THE INVENTION

[0009]The present invention relates generally to technique for handling shaped sheet materials. More particularly, the present invention provides a carrier apparatus including a top frame structure and a bottom frame structure configured to be engaged with each other and method of using the carrier apparatus for holding a shaped sheet material to perform any process or storage. Merely by way of example, the invention has been applied for handling deformable silicon sheets or thin wafers of 10 to 200 microns in thickness and 50 millimeters and greater in lateral dimension produced by a layer transfer technique based on RFQ linear accelerator system and used for a variety of applications including photovoltaic cells. But it will be recognized that the invention has a wider range of applicability.

[0010]Because the thickness of the sheet material is in a range from 10 to 200 microns, the sheet material is likely to be deformable and is susceptible to handling related damage. According to certain embodiments of the present invention, a carrier apparatus with one or more frame structures is provided for safe and convenient handling of such sheet materials. In particular, the carrier apparatus can have a top frame structure and a bottom frame structure that can be mutually engaged to secure the shaped sheet material in between. In one embodiment, the mating surface of the bottom frame structure can have a stepped inner peripheral region adapted to enclose and hold the shaped sheet material. Then the mating surface of the top frame structure is engaged with the mating surface of the bottom frame structure so that the shaped sheet material is held in. It is followed by completing a locking mechanism to couple the top frame structure and the bottom frame structure together. In another embodiment, the carrier apparatus can have two half frame members that can be engaged together to form a closed loop, each half frame members including a cut-in slot on its inner surface configured to receive a shaped sheet material. The two half frame member can be engaged together by using sliding slot/hole design in one embodiment. A locking mechanism for coupling two half frame members can be used for securing the loaded shaped sheet material. In a specific embodiment, one or two frame structures include a shaped wing structure extended from outer peripheral edges for convenience of storing and transporting the carrier apparatus. Certain embodiments of the invention provides a carrier cassette for loading a plurality of those carrier apparatus holding shaped sheet materials, so that multiple sheet material can be processed, transported, stored, or shipped in groups.

[0011]In a specific embodiment, the present invention provides a carrier apparatus for holding a shaped sheet material. The apparatus includes a first frame structure having a first front surface including a first outer peripheral region and a first inner peripheral region separated by a first step. The first inner peripheral region is characterized by a width of a ledge extended circumferentially from the first step and one or more athwart dimensions from the first step at one side of the first inner peripheral region to the first step at an opposing side of the first inner peripheral region in one or more diagonal orientations. The apparatus further includes a second frame structure characterized by a second front surface including a second outer peripheral region and a second inner peripheral region separated by a second step. The second front surface is configured to engage with the first front surface at a close position so that the second outer peripheral region is at least partially in contact with the first outer peripheral region and the second step circumferentially mates the first step with the second inner peripheral region opposing to the first inner peripheral region by a gap. Additionally, the apparatus includes one or more locking mechanisms to withhold the second frame structure engaged with the first frame structure. Furthermore, the carrier apparatus includes a shaped wing structure integrally extended from outer peripheral edge of the first frame structure.

[0012]In another specific embodiment, the present invention includes a carrier apparatus for holding a shaped sheet material. The apparatus includes a first C-like frame member including two first arm sections each with a first length from a first base to a first end integrally extended from a first middle section. Each of the two first arm sections includes two side-ridges with substantially first half of the first length from the first end. A middle slot is formed between the two side ridges. A middle hole is extended further from the middle slot with a same lateral dimension and substantially second half of the first length. Additionally, the apparatus includes a second C-like frame member including two second arm sections each with a second length from a second base to a second end integrally extended from a second middle section. Each of the two second arm sections includes a middle rod with substantially first half of the second length from the second end and two side slots further extended substantially second half the second length. The second length is substantially equal to the first length. The middle rod is configured to slidingly mate with the middle slot and further with the middle hole till a close position as the two side slots fully engage with the two side-ridges. Moreover, the apparatus includes a first trench formed through a first inner side of the first C-like frame member with a predetermined depth and cross-section shape. The first trench is offset the middle hole and two side ridges. Furthermore, the apparatus includes a second trench formed through a second inner side of the second C-like frame member with substantially the same predetermined depth and the cross-section shape. The second trench and the first trench are connected at the close position.

[0013]In an alternative embodiment, the present invention provides a carrier cassette for a plurality of carrier apparatus. The carrier cassette includes a length of a bulk structure with a U-like cross section including a bottom surface and an inner surface. The inner surface includes a plurality of slots disposed perpendicular to the length of the bulk structure with a predetermined spacing between each other. Each of the plurality of slots is configured to be inserted with a carrier apparatus. The carrier apparatus includes a first frame structure having a first front surface including a first outer peripheral region and a first inner peripheral region separated by a first step. The first inner peripheral region is characterized by a width of a ledge extended circumferentially from the first step and one or more athwart dimensions from the first step at one side of the first inner peripheral region to the first step at an opposing side of the first inner peripheral region in one or more diagonal orientations. The carrier apparatus also includes a second frame structure characterized by a second front surface including a second outer peripheral region and a second inner peripheral region separated by a second step. The second front surface is configured to engage with the first front surface at a close position so that the second outer peripheral region is at least partially in contact with the first outer peripheral region and the second step circumferentially mates the first step with the second inner peripheral region opposing to the first inner peripheral region by a gap. The carrier apparatus further includes one or more locking mechanisms to secure the second frame structure engaged with the first frame structure. Furthermore, the carrier apparatus includes a shaped wing structure integrally extended from outer peripheral edge of the first frame structure. The carrier cassette additionally includes one or more holes disposed at the bottom portion of each of the plurality of slots penetrating through the bottom surface. In one embodiment, the carrier cassette further includes one or more handles.

[0014]In yet another alternative embodiment, the present invention provides a method for handling a shaped sheet material. The method includes providing a shaped sheet material characterized by one or more lateral dimensions and a thickness and providing a carrier apparatus adapted to the shaped sheet material based on at least information of the one or more lateral dimensions and the thickness. The carrier apparatus includes at least a first frame structure having a first front surface including a first outer peripheral region and a first inner peripheral region separated by a first step. The first inner peripheral region is characterized by a width of a ledge extended circumferentially from the first step and one or more athwart dimensions from the first step at one side of the first inner peripheral region to the first step at an opposing side of the first inner peripheral region in one or more diagonal orientations. The carrier apparatus also includes a second frame structure characterized by a second front surface including a second outer peripheral region and a second inner peripheral region separated by a second step. The second front surface is configured to engage with the first front surface at a close position so that the second outer peripheral region is at least partially in contact with the first outer peripheral region and the second step circumferentially mates the first step with the second inner peripheral region opposing to the first inner peripheral region by a gap. The carrier apparatus further includes one or more locking mechanisms to secure the second frame structure engaged with the first frame structure and a shaped wing structure integrally extended from outer peripheral edge of the first frame structure. Additionally, the method includes exposing the first front surface and loading the shaped sheet material onto the first inner peripheral region. Moreover, the method includes disposing the second frame structure to mate the first frame structure so that the second front surface engages with the first front surface at the close position of the carrier apparatus and securing the engaged first frame structure and the second frame structure. Furthermore, the method includes transferring the carrier apparatus to process the shaped sheet material held therein. In one embodiment, both sides of the shaped sheet material can be processed simultaneously.

[0015]Additional embodiments and features are set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the specification or may be learned by practice of the invention. The features and advantages of the invention may be realized and attained by means of the machinery, instrumentalities, combinations, and methods described in the specification as well as in claims herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1A is a schematic diagram of a top view of a carrier apparatus for a shaped sheet material in an open position according to an embodiment of the present invention;

[0017]FIG. 1B shows an AA' cross sectional view of a top frame section and a BB' cross sectional view of a bottom frame section cutting along the directions marked in FIG. 1A;

[0018]FIG. 1C is a schematic diagram of a top view of the carrier apparatus in FIG. 1A loaded with a shaped sheet material into the bottom frame section according to an embodiment of the present invention;

[0019]FIG. 1D is a schematic diagram of a top view of the carrier apparatus in a close position with loaded shaped sheet material according to an embodiment of the present invention, including an HH' cross sectional view;

[0020]FIG. 1E is a schematic diagram of a carrier apparatus with a cover circumferentially coupled to each frame structure according to another embodiment of the present invention;

[0021]FIG. 2 is simplified flowchart showing a method for handling a shaped sheet material according to an alternative embodiment of the present invention;

[0022]FIG. 3A is an exemplary top view of a carrier apparatus with two frame members at an open position for a shaped sheet material according to another embodiment of the present invention, including a YY' cross sectional view of the frame member with a slot on inner surface;

[0023]FIG. 3B is an exemplary top view of the carrier apparatus in FIG. 3A at a close position according to another embodiment of the present invention;

[0024]FIG. 3C is an exemplary top view of the carrier apparatus in FIGS. 3A and 3B at a close position with a shaped sheet material being held therein according to another embodiment of the present invention;

[0025]FIG. 4 is a simplified diagram showing a carrier apparatus with a top view of a first frame structure having an extended wing structure and a mating second frame structure for holding a shaped sheet material according to an embodiment of the present invention;

[0026]FIG. 5A is a prospect view of a carrier cassette with a plurality of matched slots each configured to hold a carrier apparatus according to an alternative embodiment of the present invention; and

[0027]FIG. 5B is a prospect view of the carrier cassette in FIG. 5A holding two carrier apparatuses each holding a shaped sheet material therein according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028]The present invention relates generally to technique for handling shaped sheet materials. More particularly, the present invention provides a carrier apparatus including a top frame structure and a bottom frame structure configured to be engaged with each other and method of using the carrier apparatus for holding a shaped sheet material to perform any process or storage. Merely by way of example, the invention has been applied for handling deformable silicon sheets or thin wafers of 10 to 200 microns in thickness and 50 millimeters and greater in lateral dimension produced by a layer transfer technique based on RFQ linear accelerator system and used for a variety of applications including photovoltaic cells. But it will be recognized that the invention has a wider range of applicability.

[0029]FIG. 1A is a schematic diagram of a top view of a carrier apparatus for a shaped sheet material in an open position according to an embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims herein. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. As shown, the carrier apparatus 100 including two frame structures (110 and 160) coupled each other by one or more hinges (130) is illustrated in an open position. A frame structure 110 in bottom part of the FIG. 1A reveals a surface in a closed loop including an outer peripheral region 112 and an inner peripheral region 114 separated by a circumferential step 116. In one embodiment, the inner peripheral region 114 can be viewed as a width 120 of a ledge extended from the step 116 circumferentially. Of course, the width 120 can vary along the periphery though in most portions of the inner peripheral region it can be made substantially equal to a same value for simpler process or lower cost.

[0030]In another embodiment, the step 116 (visible as a loop line in the top view) circumferentially can be characterized by one or more athwart dimensions in one or more orientations, for example, athwart lengths 121, 122, 123, and 124 as shown in FIG. 1A from one side the step 116 across the frame structure to the opposing side of the step 116. Depending on the shape defined by the step 116, a single critical length can characterize a circle; two critical lengths in two or more orientations can characterize a square; three critical lengths in three or more orientations can characterize a rectangle; etc. Of course, there can be many alternatives, variations, and modifications.

[0031]Another frame structure 160 shown in top part of the FIG. 1A is substantially similar to the frame structure 110 in shape and characteristic dimensions. As shown, the frame structure 160 reveals another surface in closed loop including an outer peripheral region 162 and an inner peripheral region 164 separated by another circumferential step 166. FIG. 1A also shows that two hinges 130 couple the frame structure 110 and frame structure 160 at the respective edges of the outer peripheral region 112 and the opposing outer peripheral region 162. In addition, FIG. 1A also shows a locking mechanism which may include two parts, one lock part 150a being coupled to the frame structure 160 and another mating lock part 150b being coupled to the frame structure 110. More detail features of the carrier apparatus 100 can be found throughout the specification and specifically below.

[0032]One structural features of the carrier apparatus 100 can be further illustrated by cross sectional views. FIG. 1B shows an AA' cross sectional view of a top frame structure 160 and a BB' cross sectional view of a bottom frame structure 110 cutting along the directions marked in FIG. 1A. This diagram is merely an example, which should not unduly limit the scope of the claims herein. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. As shown, the surface of the top frame structure 160 revealed in FIG. 1A includes the outer peripheral region 162 and the inner peripheral region 164 and both face up in FIG. 1B and are separated by an up-step (i.e. the step 166) from the region 162 to region 164. Similarly shown, the surface of the bottom frame structure 110 revealed in FIG. 1A includes the outer peripheral region 112 and the inner peripheral region 114 and both face up and are separated by an down-step (i.e., the step 116) from region 112 to region 114. Also clearly shown is the width 120 of the inner peripheral region 114.

[0033]In one embodiment, in terms of the cross sectional view, the lateral dimensions (including 120) of inner peripheral regions 114 and 164 are configured to be properly mated with each other. For example, the width 120 is substantially equal to or slightly bigger than the corresponding width of the inner peripheral region 164. As shown in the bottom part of FIG. 1B, the top frame structure 160 is able to be flipped to engage with bottom frame structure 110. In another embodiment, the step 116 is predetermined to be bigger than the step 166 in step height so that a gap can be seen after the two frame structures are fully engaged. The gap spacing 140 is predetermined to adapt to a (standard) thickness of the sheet material or thin wafer to be handled. For example, a thickness of the silicon sheet material produced by cleaving a bulk single-crystalline or polycrystalline silicon material for solar cell application can be ranging from 10 to 200 microns. The gap spacing 140, i.e., the difference between step 116 and step 166, can be selected as 10 to 200 microns plus a positive margin of about 5% to 10% of the thickness. In yet another embodiment, the step up or down direction associated with step 166 or step 116 also provides advantages for securing the shaped sheet material to be held and stabilizing the mutual engagement between the two frame structures (110 and 160). In yet still another embodiment, the step edges of the inner peripheral regions 114 and 164 can be rounded to reduce the surface damage to the sheet material being held.

[0034]In another embodiment, in terms of the two dimensional view, the shape of step 166 characterized by one or more athwart dimensions shall be configured to match with the shape of the step 116 circumferentially. In certain embodiments, the shape defined by the step 116 and associated one or more athwart dimensions are configured to adapt the corresponding shape and lateral dimensions of sample material that is to be held by this apparatus. For example, a thin wafer of silicon shall bear the same shape of the bulk ingot material which may have been pre-shaped into a cylinder with substantially square shape cross section with rounded corner edges. Therefore, the shape of the inner peripheral region 114 in terms of the step 116 will be configured to match at least the straight edge portions and may leave extra room for corners. Embodiments of the present invention have no restriction on exact shapes that the step 116 can define, though one preferred application is for handling the thin silicon sheets or wafers used for photovoltaic cells that has a substantially square shape (with truncated or rounded corners) with side-to-side dimension of about 100 millimeters, or about 125 millimeters, or about 156 millimeters. Of course, other embodiments of the present invention can be applied to a much broader fields for handling various types of shaped sheet materials.

[0035]FIG. 1C is a schematic diagram of a top view of the carrier apparatus in FIG. 1A loaded with a shaped sheet material into the bottom frame section according to an embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims herein. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. As shown, the shaped sheet material 180 characterized by one or more lateral dimensions 121a through 124a and a thickness (not visible by this top view diagram) is loaded into the inner peripheral region 114 of the frame structure 110. For example, the shaped sheet material 180 may be a thin silicon wafer produced by cleaving a bulk single-crystalline or polycrystalline silicon material for solar cell application. In another example, the shaped sheet material 180 can be made of germanium, or III/V group compound semiconductor for other applications. Of course, there can be many alternatives, variations, and modifications.

[0036]FIG. 1C is an exemplary illustration that the carrier apparatus 100 has been configured to adapt the shape and dimension of the inner peripheral region of the bottom frame structure to the shaped sheet material 180. Specifically, the one or more athwart dimensions 121 through 124 are correspondingly adapted to the one or more lateral dimensions 121a through 124a. Furthermore, the width 120 of the inner peripheral region 114, i.e., the width between the step 116 and the edge of the inner peripheral region (indicated by a dashed line in FIG. 1C) in certain orientation is about 5% of the athwart dimension in that orientation of the circumferential step 116. In one embodiment, the width 120 is configured to support at least one or more peripheral portion of the shaped sheet material 180.

[0037]Ideally the inner peripheral region 114 can be adapted to support full peripheral portion of the shaped sheet material, but practically, only partial portions of the periphery need to be supported, depending on particular shape of the sheet material. As shown in FIG. 1 C, the shaped sheet material 180 is a substantially square shape with truncated or rounded corners. For example, the shaped sheet material 180 is a thin silicon wafer of 100 millimeters and greater in lateral dimension produced by a layer transfer technique based on RFQ linear accelerator system and used for a variety of applications including photovoltaic cells. Therefore, the four major side edges of the shaped sheet material have been properly enclosed within the step 116 and been supported by the inner peripheral region 114. For example, the width of the inner peripheral region for supporting the major side edges is about 5 mm or greater for an 100 mm-sized thin wafer. Of course, there can be many alternatives, variations, and modifications. For example, the corners of the inner peripheral region can have extended spacing beyond the actual corner of the thin wafer. In another example, the width of inner peripheral region near the corners can be much smaller to reduce some contact area without affecting stability of the thin wafer being held in the carrier apparatus. In yet another example, around extended area of corners the widths of inner peripheral region can be wider while the widths around major side edge correspondingly are reduced to some extent without affecting stability of the thin wafer being held in the carrier apparatus.

[0038]FIG. 1D is a schematic diagram of a top view of the carrier apparatus in a close position with loaded shaped sheet material according to an embodiment of the present invention, and a HH' cross sectional view is also shown. According to one embodiment as shown in the top view, the top frame structure 160 is flipped to allow the revealed surface of frame structure 160 in FIG. 1A to be engaged with the revealed surface of frame structure 110 in FIG. 1A. Therefore, the frame structure 160 now completely covers frame structure 110 as well as the peripheral portion of the shaped sheet material 180. Schematically shown as an example, the shaped sheet material 180 is fully enclosed within the step 166. In this close position, lock part 150a on frame structure 160 correspondingly engages with mating lock part 150b on frame structure 110 to become a full lock 150 as shown in FIG. 1D. According to an embodiment as shown in the HH' cross sectional view, the frame structure 160 is capable to fully engage with the frame structure 110 holding a shaped sheet material 180 of a thickness 185 in between the gap spacing 140. This diagram is merely an example, which should not unduly limit the scope of the claims herein. One of ordinary skill in the art would recognize many variations, alternatives, and modifications.

[0039]In one embodiment, the carrier apparatus 100 can be made by various materials depending on applications. For example, the carrier apparatus can be made by Teflon, PVDF (Polyvinylidene Difluoride), PEEK (Polyetheretherketones), PET (polyethylene terephthalate), polyimide, or other plastic materials using molds. In some cases, other engaging and fixing mechanisms may be applied to replace the hinges or locks. For example, flat head screws may be used to mount two frame structures together without extra hinges or handles so that the carrier apparatus can be easily fit into a cassette allowing groups of thin wafer to be transferred from one process to the other process during wafers process. In another example, the carrier apparatus can be made by Quartz, ceramic or glass material for the convenience of performing certain chemical processes. In yet another example, the carrier apparatus can also be made of metal including, but not limit to, aluminum, molybdenum, anodized aluminum, stainless steel, or metal alloys. For example, transition metal alloy containing elements of nickel, molybdenum, chromium, cobalt, iron, copper, manganese, titanium, zirconium, aluminum, carbon, and tungsten can be used for providing highly corrosion resistant characteristics which is useful for performing many chemical treatments to the shaped sheet material held by the carrier apparatus. One example of such transition metal alloy is Hastelloy.TM. made by Haynes International, Inc. Of course, there can be many alternatives, variations, and modifications.

[0040]FIG. 1E is a schematic diagram of a carrier apparatus with a cover circumferentially coupled to each frame structure according to another embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims herein. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. In one embodiment, the carrier apparatus 100a can be substantially the same as the carrier apparatus 100 shown in FIGS. 1A-1D except that the carrier apparatus 100a has an additional cover on each frame structure. In particular, as shown in FIG. 1E, the cover 170 integrally and circumferentially couples to the edge of the inner peripheral region. In one embodiment, the cover 170 can be made the same material as that for the rest parts of the carrier apparatus. In another embodiment, depending on applications, the cover 170 can be made from a material different from that for the rest parts of the carrier apparatus. The carrier apparatus 100a with cover 170 on each frame usually is preferred for the application of storage and shipping.

[0041]FIG. 2 is a simplified flowchart showing a method for handling a shaped sheet material according to an alternative embodiment of the present invention. This diagram is merely an example, particularly using a carrier apparatus with a first frame structure and a second frame structure coupled by one or more hinges, which should not unduly limit the scope of the claimed herein. For example, various processes may be added, removed, replaced, repeated, overlapped, and/or partially overlapped. The method 200 includes the following processes:

[0042]1. Process 210 for providing a shaped sheet material;

[0043]2. Process 212 for providing a carrier apparatus including a first frame structure and a second frame structure;

[0044]3. Process 214 for exposing the first frame structure;

[0045]4. Process 216 for loading the shaped sheet material onto the first frame structure;

[0046]5. Process 218 for engaging the second frame structure with the first frame structure to close the carrier apparatus holding the shaped sheet material;

[0047]6. Process 220 for transferring the carrier apparatus to process the shaped sheet material held therein.

[0048]The above sequence of processes provides a method according to an embodiment of the present invention. Other alternatives can also be provided where processes are added, one or more processes are removed, or one or more processes are provided in a different sequence without departing from the scope of the claims herein. Alternate carrier apparatus may be used. For example, the second frame structure is added to engage with the first frame structure loaded with the shaped sheet material, then mounted by flat head screws. Future details of the present invention can be found throughout the present specification and more particularly below.

[0049]At Process 210, the method 200 includes a step to provide a shaped sheet material. In particular, the shaped sheet material includes, but not limited to, a thin wafer produced by cleaving a bulk material including ingots of single-crystalline or polycrystalline silicon, or germanium, or III/V group compound semiconductor. For example, the cleaving process is based on a thick layer transfer technique using ion implantation from high energy ion beam generated by a linear accelerator. More detailed descriptions about the thick layer transfer in association with liner accelerator system can be found in a co-assigned U.S. patent application Ser. No. 11/935,197 by Francois J Henley et al., and titled "METHOD AND STRUCTURE FOR THICK LAYER TRANSFER USING A LINEAR ACCELERATOR", filed on Nov. 5, 2007. Typically, the produced thin wafer has a thickness in a range of 10 microns to 200 microns depending on applications. For silicon thin wafer used for photovoltaic cell application, the shape is primarily a square with rounded corners. The width/length is about 100 millimeters, or about 125 millimeters, or about 156 millimeters.

[0050]At Process 212, a carrier apparatus including a first frame structure and a second frame structure is provided. In one example, the carrier apparatus with just frame structure (100) is provided. In another example, the carrier apparatus with covers (100a) is provided. In yet another example, a carrier apparatus 300, described in the specification below, can be provided. In yet still another example, a carrier apparatus with a shaped wing structure (400), described in specification below, can also be used. According to certain embodiments of the present invention, process for providing a carrier apparatus includes determining the first frame structure that is adapted to the shaped sheet material. In particular, the shape of the first frame structure at least partially bear some analogy to the shaped sheet material. For example, the first frame structure is the bottom frame structure 110 of the carrier apparatus 100 such that the first inner peripheral region bounded by the step 116 is configured with one or more characteristic athwart dimension and a width of ledge to properly enclose and support the shaped sheet material 180. In another embodiment, the height of the step 116 is also configured to accommodate the thickness 185 of the shaped sheet material.

[0051]According to certain embodiments, the process for providing a carrier apparatus further includes determining the second frame structure. Basically, the second frame structure needs to be configured to be fully engaged with the first frame structure in a close position such that the shaped sheet material is held in between. For example, the second frame structure is the top frame structure 160. In particular, the inner peripheral region 164 associated with the top frame structure is disposed opposing to the inner peripheral region 114 of the bottom frame structure as the step 166 mates with the step 116. The height of step 166 is determined to provide a gap between the two inner peripheral regions 164 and 114 in the close position, which is large enough for accommodate the thickness of the shaped sheet material therein.

[0052]At Process 214, the method 200 including exposing the first frame structure. In one embodiment, the second frame structure is coupled to the first frame structure by one or more hinges so that the second frame structure can be flipped open by rotating the second frame structure against the one or more hinges. In one example, the hinges are capable of rotating about 180 degrees so that the first frame structure may be fully exposed. In another example, the second frame structure is flipped open to certain degrees just large enough for a shaped sheet material to be loaded successfully into the first frame structure. In an alternative embodiment, a second frame structure is not coupled to the first frame structure by hinge and can be simply removed away to allow the first frame structure exposed and ready for loading the shaped sheet material or thin wafer. Of course, there can be many alternatives, variations, and modifications. Alternative design of carrier apparatus and the method of use can be found in later part of the specification.

[0053]At Process 216, the shaped sheet material is loaded onto the first frame structure. In one example, the shaped sheet material is a thin wafer cleaved from a bulk material with a thickness in a range of 10 to 200 microns. The state-of-art techniques for handling such thin wafer includes using of electrostatic chuck or vacuum chuck. For example, a robot with an electrostatic chuck plate may be used. As the chuck plate is disposed to a proximity position of the thin wafer, a chuck voltage with a predetermined polarity and value can be applied to the chuck plate to generate an attractive electrostatic force to suck the thin wafer to the plate. Then it can be transferred by the robot toward the right position as planned. As the shaped sheet material or thin wafer is fully enclosed within the step 116 associated with the inner peripheral region of the first frame structure. A predetermined dechucking voltage can be applied to clear the electrostatic force so that the shaped sheet material can freely rest on the inner peripheral region, and the robot can be retracted. Of course, there can be many alternatives, variations, and modifications.

[0054]At Process 218, the method 200 includes engaging the second frame structure with the first frame structure to close the carrier apparatus holding the shaped sheet material. In one embodiment, the second frame structure is coupled to the first frame structure by one or more hinges so that the second frame structure can be flipped close by rotating the second frame structure against the one or more hinges. In another embodiment, the (separated) second frame structure is directly disposed on top the first frame structure with the corresponding surfaces engaged each other so that the loaded shaped sheet material is enclosed therein. Subsequently, a locking mechanism may be applied to secure the engagement. The locking mechanism includes one or more clips, or one or more screws, or one or more springs, or one or more latches. For example, after two separated frame structures engage each other, one or more flat head screws can be applied to one or more predrilled holes (threaded hole or through-hole with stop region) near the corners of the frame structures to completely tied them together, thereby securing the shaped sheet material held therein. Of course, there can be many alternatives, variations, and modifications.

[0055]At Process 220, the carrier apparatus can be transferred to one or more process stations to process the shaped sheet material held therein. In one embodiment, the carrier apparatus is individually transferred. In another embodiment, multiple carrier apparatuses can be loaded into a cassette or wafer boat which has been configured to include multiple slots each designed for vertically holding one carrier apparatus. For example, for convenience of holding the carrier apparatus into the slot, the carrier apparatus with a locking mechanism using one or more flat head screws can be used. In another example, the carrier apparatus with a shaped wing structure extended from outer peripheral edge can be used. The shaped wing structure can be configured to have certain diameter and thickness to fit in each slot of the standard cassette or wafer boat. The slot-to-slot spacing has been adapted to a total thickness of the carrier apparatus so that one carrier apparatus loaded in one slot has clearance spacing from another carrier apparatus loaded in a neighboring slot. Of course, the cassette or wafer boat can be adapted for various variations of the carrier apparatus structure.

[0056]After loaded with multiple carrier apparatuses, the cassette can then be transferred to one or more process stations to allow a group of shaped sheet material to be processed. Note each carrier apparatus is characterized by a frame structure or engaged frame structures. Therefore the major portions of two surfaces of the shaped sheet material are exposed and then can be processed simultaneously within the process station. The process involved includes, but not limited to, standard wet-bench cleaning, chemical etching, deposition, thermal annealing, and certain material characterization. In an alternative embodiment, the carrier apparatus can include a cover coupled to each frame structure so that the surfaces of the shaped sheet material do not expose directly. In addition, the carrier apparatus can include hinges to couple the two frame structures and clip locking mechanism. These types of carrier apparatuses may be handled individually and preferred for storage, shipping and other wafer transfer applications requiring to keep the surfaces from being contaminated or dusted. Of course, there can be many alternatives, variations, and modifications. More details about alternative carrier apparatus structures and cassette design can be found in specification below.

[0057]FIG. 3A is an exemplary top view of an alternative carrier apparatus with two frame members at an open position for a shaped sheet material according to another embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims herein. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. As shown, the carrier apparatus 300 includes two C-like frame members 310 and 360. The frame member 310 includes a middle section 315 and two arm sections 317a and 317b each extended integrally from two ends of the middle section 315 to form a C-like shape. The C-like frame member 310 naturally includes an inner surface 316 and an outer surface 318, shown just lines in the top view section of FIG. 3A. In one embodiment, the curvature and dimensions associated with the middle section 315 and/or two arm section can be determined to adapt the shaped sheet material. For example, the shaped sheet material can be substantially a square with four rounded or truncated corners.

[0058]As shown in FIG. 3A, the two arm sections include some unique structural features. Firstly, in one example, the two arm sections 317a and 317b can be substantially the same in terms of a length, width, and some relevant structure details. Secondly, each arm section includes two side ridges, side ridge 311a for arm section 317a, or side ridge 311b for arm section 317b, integrally coupled to rest of the corresponding arm section with half the arm length starting from the end. In between the two side ridges, it is an open slot 312 which extends also from the end of arm section and further deep into the arm section by another half arm length, forming a hole 313a for arm section 317a or a hole 313b for arm section 317b. Referring to the FIG. 3A, the top view reveals the shape of the side ridges, the open slot, and the hole all are in rectangular shape. Of course, there can be many alternatives, variations, and modifications.

[0059]In one embodiment, another frame member 360 has a substantially similar structure as the frame member 3 10. In particular, the frame member 360 includes a middle section 365 and two arm sections 367a and 367b each integrally extended from the two ends of the middle section 365 to form a C-like shape. The C-like frame member 360 includes an inner surface 366 and an outer surface 368. In another embodiment, the two arm sections 367a and 367b may be substantially redundant or different depending on the shape of the sheet material to be loaded. In yet another embodiment, the arm section 367a includes a rod 363a with a half arm length starting from the end of the arm section and similarly the arm section 367b has a rod 363b. The arm section 367a further includes two side slots 316a disposed from the location of half arm length to extend another half arm length along the arm section. Similarly the arm section 367b includes two side slots 361b. In a specific embodiment, the rod 363a/363b is configured to be slid into the open slot 312a/312b and further be engaged with the hole 311a/311b at a close position, thereby forming a complete closed loop frame for holding the shaped sheet material therein. The arm sections with sliding rod/slot structure also serves a locking mechanism. Of course, there can be many alternatives, variations, and modifications.

[0060]A YY' cross sectional view is illustrated at the lower part of FIG. 3A, showing the inner surface 316 or 366 and outer surface 318 or 368. It is seen that the inner surface 316 or 366 has a cut-in slot 320 or slot 370 with a predetermined depth 321 or depth 371 respectively. The slot is configured to receive the shaped sheet material. For the convenience of insert the sheet material the opening of the slot near the inner surface is relatively wider and the width gradually is reduced to a certain value towards the bottom of the slot. In one embodiment, the minimum width of the slot shall accommodate a thickness of the shaped sheet material to be inserted. Referring to the top view part of FIG. 3A, the middle dashed line represents the bottom line of the slot along the whole inner surface for both frame member 310 and frame member 360. When the frame member 360 is engaged with the frame member 310, the cut-in slot 320 and slot 370 merges together. In addition, the inner surface has been adapted to the shaped sheet material so that the combined cut-in slot 320 plus slot 370 can be used to hold the shaped sheet material circumferentially. In a specific embodiment, the cut-in slot near the arm section can be offset from those side ridges or side slot to avoid interference.

[0061]In one embodiment, the carrier apparatus 300 can be made by various materials depending on applications. For example, the carrier apparatus can be made by Teflon, PVDF (Polyvinylidene Difluoride), PEEK (Polyetheretherketones), PET (polyethylene terephthalate), polyimide, or other plastic materials using molds. In some cases, other engaging and fixing mechanisms may be applied to replace the hinges or locks. For example, flat head screws may be used to mount two frame structures together without extra hinges or handles so that the carrier apparatus can be easily fit into a cassette allowing groups of thin wafer to be transferred from one process to the other process during wafers process. In another example, the carrier apparatus can be made by Quartz, ceramic or glass material for the convenience of performing certain chemical processes. In yet another example, the carrier apparatus can also be made of metal including, but not limit to, aluminum, molybdenum, anodized aluminum, stainless steel, or metal alloys. For example, transition metal alloy containing elements of nickel, molybdenum, chromium, cobalt, iron, copper, manganese, titanium, zirconium, aluminum, carbon, and tungsten can be used for providing highly corrosion resistant characteristics which is useful for performing many chemical treatments to the shaped sheet material held by the carrier apparatus. One example of such transition metal alloy is Hastelloy.TM. made by Haynes International, Inc. Of course, there can be many alternatives, variations, and modifications.

[0062]One possible method of use associated with the carrier apparatus 300 can go through the following processes: firstly, remove one of the two C-like frame members; secondly, load in the shaped sheet material into the slot of remaining C-like frame member; thirdly, re-install the C-like frame member removed earlier by carefully sliding the rod into the open slot and hole for corresponding arm sections till a close position; and complete locking mechanism at the close position. FIG. 3B just shows an exemplary top view of the carrier apparatus in FIG. 3A at the close position according to an embodiment of the present invention. FIG. 3C is an exemplary top view of the carrier apparatus in FIGS. 3A and 3B at the close position with a shaped sheet material being held therein according to an embodiment of the present invention. These diagrams are merely examples, which should not unduly limit the scope of the claims herein. One of ordinary skill in the art would recognize many variations, alternatives, and modifications.

[0063]FIG. 4 is a simplified diagram showing a carrier apparatus with a top view of a first frame structure having an extended wing structure and a mating second frame structure for holding a shaped sheet material according to an embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims herein. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. As shown, a carrier apparatus 400 includes a first frame structure 410 and a second frame structure 460. The first frame structure 410 has a first front surface (visible in this top view) including a first outer peripheral region 412 and a first inner peripheral region 414 separated by a first step 416. The shape and dimensions of the first inner peripheral region are configured to be substantially similar to a shaped sheet material to be loaded. In one embodiment, through not being directly viewable in top view, the first inner peripheral region 414 can be positioned lower than the first outer peripheral region 412 by the step height of the first step 416 so that the shaped sheet material can be loaded in and supported by the first inner peripheral region and circumferentially confined within the first step 416. In a specific embodiment, the first frame structure without the wing structure is substantially the same the frame structure 110 (excepting the handle or hinges) as seen earlier in FIG. 1A.

[0064]As shown in FIG. 4, the first frame structure 410 includes a shaped wing structure 470 that is integrally extended from outer peripheral edge 422 of the first frame structure 410. The shaped wing structure is characterized by a shape with a lateral dimension and a thickness. The shape has no specific limit in general but its lateral dimension and the thickness are adapted to fit in a cassette or wafer boat that can hold the carrier apparatus. For example, the shaped wing structure can be made into a round peripheral shape as seen in FIG. 4 for the convenience of manufacture and handling. The diameter and thickness of the round shaped wing structure can be adapted to certain standard cassette or wafer boat. In one example, the diameter of the round wing structure can be about 4 to 12 inches depending on the frame structures required for holding certain sized shaped sheet material. The thickness of the wing structure can be about 1 mm or less. In other examples, the shaped wing structure can be an oval or a polygon with one or more lateral dimensions and a thickness fitting the corresponding cassette or wafer boat. Of course, there can be many alternatives, variations, and modifications.

[0065]In another embodiment, as shown in FIG. 4, the second frame structure 460 is configured to have substantially the same frame shape and lateral dimension as the first frame structure 410 so that both of them can be coupled together as a complete carrier apparatus 400. As shown in this top view diagram, the second frame structure 460 has a second front surface including a second outer peripheral region 462 and a second inner peripheral region 464 separated by a second step 466. Again, though not directly viewable in the top view, in one embodiment the second inner peripheral region 464 is made to be extruded above the second outer peripheral region 462 by the step height of the second step 466. In a specific embodiment, the second step 466 is configured to be substantially similar to the first step with slightly smaller lateral dimension and smaller step height. Therefore, the second frame structure 460 can be flipped over so that the second front surface is able to mate with the first front surface. In particular, the second step just fits within the first step circumferentially. In another specific embodiment, the difference in step height between the first step 416 and the second step 466 provides a space between the first inner peripheral region 414 and the second inner peripheral region 464 which is adapted for holding a shaped sheet material therein. In one example, the second frame structure 460 is substantially the same as the frame structure 160 (excepting any coupling mechanism).

[0066]In yet another embodiment, the carrier apparatus includes a locking mechanism associated with both the first frame structure 410 and the second frame structure 460 so that the two separate mechanical pieces can be securely coupled together. In particular, as shown in FIG. 4, the first frame structure 410 includes a first plurality of holes 450a disposed near corner areas of the first frame structure and the second frame structure includes a second plurality of holes 450b disposed near corresponding corner areas of the second frame structure. The holes 450a and 450b are substantially one-to-one matched in position when the second frame structure 460 engages with the first frame structure 460. In one embodiment, these holes can be threaded holes or through-holes with a stop region so that flat head screws (not shown) can be utilized for coupling both frame structures and securing the held shaped sheet material. This type of locking mechanism has no extruded structure around frame periphery providing convenience for being fitted into the cassette and being handled in group. Of course, other types of locking mechanisms can be used. One of skilled in the art should recognize many alternatives, variations, and modifications. For example, one or more hinges plus clips, one or more springs plus hooks, one or more latches plus stoppers, can be used.

[0067]In one embodiment, the carrier apparatus 400 can be made by various materials depending on applications. For example, the carrier apparatus can be made by Teflon, PVDF (Polyvinylidene Difluoride), PEEK (Polyetheretherketones), PET (polyethylene terephthalate), polyimide, or other plastic materials using molds. In some cases, other engaging and fixing mechanisms may be applied to replace the hinges or locks. For example, flat head screws may be used to mount two frame structures together without extra hinges or handles so that the carrier apparatus can be easily fit into a cassette allowing groups of thin wafer to be transferred from one process to the other process during wafers process. In another example, the carrier apparatus can be made by Quartz, ceramic or glass material for the convenience of performing certain chemical processes. In yet another example, the carrier apparatus can also be made of metal including, but not limit to, aluminum, molybdenum, anodized aluminum, stainless steel, or metal alloys. For example, transition metal alloy containing elements of nickel, molybdenum, chromium, cobalt, iron, copper, manganese, titanium, zirconium, aluminum, carbon, and tungsten can be used for providing highly corrosion resistant characteristics which is useful for performing many chemical treatments to the shaped sheet material held by the carrier apparatus. One example of such transition metal alloy is Hastelloy.TM. made by Haynes International, Inc. Of course, there can be many alternatives, variations, and modifications.

[0068]FIG. 5A is a prospect view of a carrier cassette with a plurality of matched slots each configured to hold a carrier apparatus according to an alternative embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims herein. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. As shown, the carrier cassette 500 includes a length 530 of a bulk structure with a U-like cross section including a bottom surface 520 and an inner surface 510. The inner surface 510 includes a plurality of slots 512n, where n can be an integer greater than 10, or greater than 15, or greater than 20. disposed perpendicular to the length of the bulk structure with a predetermined spacing 540 between each other. Each of the plurality of slots 512n is configured to be engaged by a carrier apparatus. For example, the carrier apparatus is the carrier apparatus 400. In another example, the carrier apparatus is the carrier apparatus 300.

[0069]In one embodiment, the U-like cross section of the bulk structure has a base width 560 which also defines the cross spacing of the plurality of slots 5 12n built-in within the inner surface 510. This width 560 is adapted to the lateral dimensions of the carrier apparatus to be loaded. For example, the shape of the U-like cross section, particularly the bottom section, is adapted to the frame structure with the shaped wing structure 470 of the carrier apparatus 400 shown in FIG. 4. In another embodiment, the U-like cross section also is characterized by a height 550 from the middle part of inner surface 510 to an upper edge of the U-like section. The height 550 is preferred to be greater than half the size of lateral dimension of the carrier apparatus so that the loaded carrier apparatus will be stable and secured within the cassette. Of course, there can be many alternatives, variations, and modifications.

[0070]In another embodiment, each slot 512n is associated with a width 540 and an inter-slot spacing 545. The width 540 is designed to hold one carrier apparatus therein. For example, the width 540 is about 1 mm which is able to receive the thickness of the shaped wing structure 470 so that the carrier apparatus can be inserted into the slot 512n. The inter-slot spacing 545 is also adapted to a total thickness of the carrier apparatus so that a carrier apparatus loaded in one slot (for example 512.sub.1) has a clearance space from another carrier apparatus loaded in a neighboring slot (for example 512.sub.2). For example, the total thickness of the carrier apparatus includes the thickness of both the first frame structure 410 and the second frame structure 460. Depending on the applications, some carrier cassette may need wider spacing between each slot based on consideration of processing conditions. Other carrier cassette can make the spacing tighter to hold as many carrier apparatus as it can. In a specific embodiment, the carrier cassette may further include one ore more handles (not shown) coupled with two upper edges or side edges of the U-like shaped bulk structure for convenience of cassette transporting or loading in/out the processing station. In another specific embodiment, the bottom part of each slot 512n can have one or more through holes 518n that allow top-down venting/convection based on certain considerations of chemical or thermal processing conditions. Of course, one of ordinary skill in the art would recognize many variations, alternatives, and modifications in those detail features under the scope of the claims herein.

[0071]FIG. 5B is a prospect view of the carrier cassette in FIG. 5A holding two carrier apparatuses each holding a shaped sheet material therein according to an embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims herein. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. As shown, one of the carrier cassette 500 is loaded with two carrier apparatus 400.sub.n and 400.sub.n+1. Each carrier apparatus sits in one slot 512n. For example, each of the carrier apparatus 400.sub.n and 400.sub.n+1 can be one of the carrier apparatus 400 shown in FIG. 4. Each carrier apparatus is holding a shaped sheet material therein. In one example, the shaped sheet material is a deformable thin wafer. In particular, the shaped sheet material is a silicon thin wafer of 10-200 .mu.m in thickness and about 50 mm, or 100 mm, or 125 mm, or 156 mm in lateral dimension produced by cleaving a bulk ingot of single-crystalline or polycrystalline silicon based on thick layer transfer technique using linear accelerator ion implantation. With this set up, every surface of each shaped sheet material held in each carrier apparatus within the groups loaded in the cassette can be processed at the same time efficiently.

[0072]Having described several embodiments, it will be recognized by those of skill in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the invention. Additionally, a number of well known processes and elements have not been described in order to avoid unnecessarily obscuring the present invention. Accordingly, the above description should not be taken as limiting the scope of the invention.

[0073]Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed. The upper and lower limits of these smaller ranges may independently be included or excluded in the range, and each range where either, neither or both limits are included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included.

[0074]It is also understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the applied claims.

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