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United States Patent Application	20070154291
Kind Code	A1
Lin; Yuan-Hsing ;   et al.	July 5, 2007

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Foreign Application Data

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Date	Code	Application Number
Dec 30, 2005	TW	94147624

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Claims

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1. A displaced wafer detection system, comprising:a unified pod enclosing a plurality of wafers in a first position;a pod opener opening the unified pod;a horizontal transmission robot carrying the wafers from the unified pod to a second position; anda sensor, when one of the wafers has reached the second position, detecting if any wafer has slipped during wafer transmission from the unified pod.

2. The system as claimed in claim 1, wherein the sensor is disposed between the horizontal transmission robot and the pod opener while the wafers are carried by the horizontal transmission robot from the unified pod to the second position.

3. The system as claimed in claim 2, wherein the sensor is fixed to a first surface of the pod opener, and, when the horizontal transmission robot carrys the wafers from the unified pod, the first surface faces the horizontal transmission robot.

4. The system as claimed in claim 2, wherein the sensor comprises at least one transmitter dispatching a signal and one receiver accepting the signal, the wafers carried by the horizontal transmission robot are substantially parallel, when no wafer slips while being carried from the unified pod, the centers of the wafers reach and lie on a second line, the transmitter and the receiver are both disposed on a third line along which the signal is transmitted from the transmitter to the receiver, and the third line is parallel to the second line.

5. The system as claimed in claim 4, wherein the wafers when being in the opened unified pod have the centers thereof substantially lie on a first line, and the signal travels along a path on the same plane as the first and second lines.

6. The system as claimed in claim 4, further comprising a control unit determining that at least one of the wafers slips when one of the wafers has reached the second position while the receiver does not receive the signal.

7. The system as claimed in claim 4, wherein the control unit stops the horizontal transmission robot when at least one of the wafers slips.

8. A displaced wafer detection system, comprisinga unified pod enclosing a first lot of wafers in a first position;a pod opener opening the unified pod;a horizontal transmission robot carrying the wafers from the unified pod;a vertical transmission robot, when in a first orientation, acquiring the wafers and then vertically rotating the wafers to a second orientation;a transporter moving upward to support the wafers in a vertical orientation when the vertical transmission robot is in the second orientation; anda sensor detecting if any wafer drops from the vertical transmission robot before the wafers are supported by the transporter.

9. The system as claimed in claim 8, wherein the sensor is disposed between the vertical transmission robot and the transporter when the vertical transmission robot is in the second orientation, and the transporter has not supported the wafers.

10. The system as claimed in claim 9, wherein the wafers acquired by the vertical transmission robot are substantially parallel, the centers of the wafers substantially move along a vertical plane while the vertical transmission robot rotates from the first orientation to the second orientation, the sensor comprises a transmitter dispatching a signal and a receiver accepting the signal, and the transmitter and the receiver are disposed on a line substantially parallel to the vertical plane.

11. The system as claimed in claim 10, wherein the transmitter and the receiver are substantially disposed on the vertical plane.

12. The system as claimed in claim 10, further comprising a control unit determining that at least one of the wafers has dropped if the signal from the transmitter to the receiver is interrupted during a period since the wafers are acquired by the vertical transmission robot until the wafers are supported by the transporter.

13. The system as claimed in claim 12, wherein the control unit stops the transporter when at least one of the wafers drops.

14. The system as claimed in claim 12, wherein the transporter has had a second lot of wafers disposed thereon, and the control unit determines that at least one of the wafers has dropped if the signal from the transmitter to the receiver is interrupted before the first lot of wafers and the second lot of wafers are interleaved.

15. The system as claimed in claim 14, wherein the control unit stops the transporter when at least one of the wafers drops.

16. The system as claimed in claim 8, wherein the horizontal transmission robot carries the wafers from the unified pod to a second position; further comprising:a second sensor, when one of the wafers has reached the second position, detecting if any wafer has slipped during wafer transport from the unified pod.

17. The system as claimed in claim 16, wherein the sensor is disposed between the horizontal transmission robot and the pod opener while the wafers are carried by the horizontal transmission robot from the unified pod to a second position.

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Description

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BACKGROUND OF THE INVENTION

[0001]1. Field of the Invention

[0002]The present invention relates to semiconductor manufacturing techniques, and more particularly to displaced wafer detection systems.

[0003]2. Description of the Related Art

[0004]A unified pod, such as a front opening unified pod (FOUP) packing 13 or 25 pieces of 12'' wafers, is utilized to transport wafers between fabrication steps and prevents contamination of wafers. When a unified pod is sent to a pod opener, the pod opener automatically opens the door of the unified pod, and the wafers therein are acquired by other mechanisms and sent to various fabrication equipment.

[0005]FIG. 1 is a fab floor plan. When unified pod 10 is sent to pod opener 20, pod opener 20 automatically opens the door of unified pod 10. Horizontal transmission robot 30 comprises robot arms R1 and R2. Horizontal transmission robot 30 utilizes robot arm R1 to carry a wafer lot in a horizontal direction from unified pod 10 to another position. As shown in FIG. 2, the wafers remain substantially parallel. Normally, all the acquired wafers are intended to substantially reach the same position of wafer 12 in the floor plan of FIG. 2, i.e. the centers of the wafers are intended to lie on substantially the same line. Some wafers, such as wafer 11, however, may fall occasionally, e.g. the center of wafer 11 does not lie on the same line as other wafers.

[0006]When horizontal transmission robot 30 rotates to an orientation as shown in FIG. 3, the wafers are transferred from horizontal transmission robot 30 to vertical transmission robot 40, wherein the wafers remain parallel, and the wafer 11 is still incorrectly displaced. Vertical transmission robot 40 vertically rotates to make the wafers stand in a vertical orientation. Normally, when the wafers stand in the vertical orientation, transporter 50 is intended to move upward from its original position below vertical transmission robot 40 to support the wafers still in the vertical orientation, and moves the wafers along a specific track. As shown in FIG. 4, because wafer 11 is carried at an incorrect position by vertical transmission robot 40, wafer 11 may fall on transporter 50 during rotation of vertical transmission robot 40, which is called a wafer drop. While transporter 50 is moving upward from its original position below vertical transmission robot 40 to support the wafers, the wafer 11 thereon will cause support of the wafer by the transporter 50 to fail and even lead to collapse of all the wafers.

BRIEF SUMMARY OF THE INVENTION

[0007]An exemplary embodiment of a displaced wafer detection system comprises a unified pod, a pod opener, a horizontal transmission robot, and a sensor. The unified pod encloses a plurality of wafers in a first position. The pod opener opens the unified pod. The horizontal transmission robot carries the wafers from the unified pod to a second position. When one of the wafers has reached the second position, the sensor detects if any wafer slips during wafer transmission from the unified pod.

[0008]An exemplary embodiment of a displaced wafer detection system comprises a unified pod, a pod opener, a horizontal transmission robot, a vertical transmission robot, a transporter, and a sensor. The unified pod encloses a first lot of wafers in a first position. The pod opener opens the unified pod. The horizontal transmission robot carries the wafers from the unified pod. The vertical transmission robot, when in a first orientation, acquires the wafers and then vertically rotates to a second orientation. The transporter moves upward to support the wafers in a vertical orientation when the vertical transmission robot is in the second orientation. The sensor detects if any wafers have dropped from the vertical transmission robot before the wafers are supported by the transporter.

[0009]A detailed description is given in the following embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

[0011]FIG. 1 is a schematic diagram of a fab;

[0012]FIG. 2 is a schematic view of a horizontal transmission robot acquiring a wafer lot;

[0013]FIG. 3 is a schematic view of a vertical transmission robot acquiring a wafer lot;

[0014]FIG. 4 is a schematic diagram of a wafer dropping from the vertical transmission robot;

[0015]FIG. 5 is a schematic diagram of a displaced wafer detection system;

[0016]FIG. 6 is a schematic diagram of the arrangement of transmitters and receivers of a sensor;

[0017]FIG. 7 is a schematic diagram of the arrangement of transmitters and receivers of another sensor;

[0018]FIG. 8 is a side view of a sensor in a first direction;

[0019]FIG. 9 is a side view of a sensor in a second direction; and

[0020]FIG. 10 is a side view of an exemplary sensor.

DETAILED DESCRIPTION OF THE INVENTION

[0021]The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.

[0022]In a floor plan of fab 100A in FIG. 5, sensor 60 is disposed between horizontal transmission robot 30 and pod opener 20, and sensor 70 is disposed between vertical transmission robot 40 and transporter 50. Control unit 1 which may be integrated in or coupled to a manufacturing execution system (MES) dominates sensors 60 and 70 and receives detection data therefrom. Unified pod 10 encloses a plurality of wafers 13. When unified pod 10 is sent to pod opener 20, pod opener 20 automatically opens the door of unified pod 10, wherein wafers 13 are substantially parallel and in a first position. The centers of wafers 13 in the opened unified pod 10 lie substantially on a first line.

[0023]Horizontal transmission robot 30 comprises robot arms R1 and R2. Horizontal transmission robot 30 utilizes robot arm R1 to horizontally carry wafers 13 from unified pod 10 to a second position, wherein wafers 13 remain substantially parallel. When no wafer slips while being carried from unified pod 10, the centers of wafers 13 reach and lie on a second line. When one of the wafers has reached the second position, sensor 60 detects if any wafers slipped during transport of wafers 13 from unified pod 10 to the second position by horizontal transmission robot 30. Sensor 60 is disposed between horizontal transmission robot and the pod opener while wafers 13 are carried by horizontal transmission robot 30 from unified pod 10 to the second position. Sensor 60 may be fixed to pod opener 20 or horizontal transmission robot 30, or even to another movable or stationary equipment or object. For example, sensor 60 is fixed to a first surface of pod opener 20, facing horizontal transmission robot 30 while horizontal transmission robot 30 is carrying wafers 13 from unified pod 10.

[0024]Sensor 60 comprises at least one transmitter dispatching a signal and one receiver accepting the signal. The transmitter and the receiver may be disposed on a third line parallel to the second line, whereby detection signals are transmitted from the transmitter to the receiver along the third line. The path of the detection signals lies substantially on the same plane as the first and the second lines. Control unit 1 may direct the transmitter to deliver detection signals when horizontal transmission robot 30 has delivered wafers 13 from unified pod 10 to the second position. Control unit 1 determines that at least one of wafers 13 slips when one of wafers 13 has reached the second position when the receiver does not receive the delivered detection signals. Control unit 1 stops horizontal transmission robot 30. The detection signals are preferably implemented by infrared or other means that does not affect the wafers.

[0025]Sensor 60 may also be implemented by coupling of transmitters and receivers. As shown in FIG. 6, transmitters 61 transmit detection signals 63 to receivers 62. If transmitters 61 and receivers 62 are arranged horizontally to align all wafers, sensor 60 can further identify and report a sliding wafer to control unit 1. As shown in FIG. 10, a side view of an example of sensor 60 is provided. The closer the path of detection signals 63 to wafers 13, the finer is the wafer sliding detection ability of sensor 60.

[0026]When horizontal transmission robot 30 rotates to an orientation as shown in FIG. 3, wafers 13 are transferred from horizontal transmission robot 30 to vertical transmission robot 40. Vertical transmission robot 40 acquires wafers 13 when in a first orientation, and then vertically rotates to a second orientation to make wafers 13 stand in a vertical orientation.

[0027]Normally, when vertical transmission robot 40 is in the second orientation transporter 50 moves upward from its original position below vertical transmission robot 40 to support wafers 13 in a vertical orientation, and moves wafers 13 along a specific track. Transporter 50 can carry two lots of wafers, wherein wafers of a second lot are inserted between wafers of a first lot. Sensor 70 detects if any wafers dropped from vertical transmission robot 40 during the period from the beginning of rotation of vertical transmission robot 40 to support of wafers 13 by transporter 50.

[0028]Sensor 70 is disposed between vertical transmission robot 40 and transporter 50 when vertical transmission robot 40 is in the second orientation, and wafers 13 have not been supported by transporter 50. Sensor 70 may be fixed to transporter 50 or vertical transmission robot 40, or even to another movable or stationary equipment or object.

[0029]Wafers 13 acquired by vertical transmission robot 40 are substantially parallel. The centers of wafers 13 substantially move along a vertical plane while vertical transmission robot 40 rotates from the first orientation to the second orientation. Sensor 70 comprises at least one transmitter dispatching a signal and one receiver accepting the signal. The transmitter and the receiver may be disposed on a fourth line substantially parallel to or lying on the vertical plane.

[0030]Control unit 1 determines that at least one of the wafers 13 drops if the signal from the transmitter to the receiver is interrupted during a period since wafers 13 are acquired by vertical transmission robot 40 until wafers 13 are supported by transporter 50. Control unit 1 may accordingly stop transporter 50 when at least a wafer drops.

[0031]Sensor 70 may also be implemented by coupling of transmitter and receiver. In a floor plan of sensor 70 as shown in FIG. 7, transmitters 71 transmit detection signals 73 to receivers 72. If transmitters 71 and receivers 72 align every wafer, sensor 70 can further identify and report a dropping wafer to control unit 1. As shown in FIG. 8, a side view of an exemplary sensor 70 is provided. Wafers 14 are wafers previously acquired by transporter 50. Wafers 13 and 14 are interleaved on transporter 50.

[0032]A side view of another exemplary sensor 70 is provided in FIG. 9. FIGS. 8 and 9 are side views of examples of sensor 70 in different directions. Under a condition when wafers 14 have been disposed on transporter 50, control unit 1 determines that at least one of the wafers 13 has dropped if the detection signals from transmitter 71 to receiver 72 are interrupted during a period since vertical transmission robot 40 acquires wafers 13 until wafers 13 and wafers 14 are interleaved. Control unit 1 may accordingly stop transporter 50.

[0033]Control unit 1 detects wafer sliding or dropping events utilizing sensors 60 and 70. When a wafer slide or a wafer drop event is detected, control unit 1 stops equipment carrying wafers and equipment acquiring the wafers and restarts the stopped equipment when problems caused by wafer sliding or wafer dropping are addressed, thus wafer damage caused by a small number of sliding and dropping wafers is prevented.

[0034]While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.

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