A lithographic system includes an illumination system for providing a projection beam of radiation, a mask table for supporting a mask, the mask serving to impart the projection beam with a pattern in its cross-section, a substrate table for holding a substrate, and a projection system for projecting the patterned beam onto a target portion of the substrate. The system also comprises a processor arranged to calculate overlay corrections using a reference height map representing a surface of the substrate table or the mask table. Feed forward correction of non-flatness induced wafer grid distortion is allowed during alignment and during exposure, thereby reducing overlay errors caused by differences in flatness characteristics. It provides an indirect qualification method for overlay accuracy related to exposure chuck flatness based on height map information.

A movable carriage for moving an article support member in a lithographic apparatus is provided. The article support member is constructed and arranged to move and support an article to be placed in a beam path of the lithographic apparatus. The carriage includes a compartmented composite structure.

A burl plate for use in immersion lithography has a higher burl density in a peripheral portion than in a medial portion so that when a higher pressure differential is applied in the peripheral portion the compression of the burls in the peripheral portion is substantially the same as in the medial portion.

An electrostatic clamp assembly for a lithographic apparatus is provided. The clamp assembly includes an electrostatic clamp structured to clamp an article against an article support structure during projection of a beam of radiation, and a controller structured to control at least one of the clamp and a backfill gas pressure to release the article from the article support structure by use of the backfill gas pressure.

A lithographic projection apparatus includes a radiation system for providing a beam of radiation, and a substrate holder. The substrate holder includes a plurality of protrusions for providing a substantially flat plane of support for supporting a substrate in a beam path of the beam of radiation, at least one clamping electrode for generating an electric field for clamping the substrate against the substrate holder, and a peripheral supporting edge arranged to contact the substrate. The electrode extends beyond the peripheral supporting edge for providing a torsion load to level the substrate near the edges of the substrate.