Patent ID: 7161662

Claim:
A lithographic projection apparatus comprising: a radiation system for providing a beam of radiation; and a substrate holder comprising a plurality of protrusions for providing a substantially flat plane of support for supporting a substrate in a beam path of said 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, wherein said at least one electrode extends beyond said peripheral supporting edge and is configured to generate a torsion load that ranges from 0.1 and 3 times a reference torsion load defined by M = 1 12 ⁢ Δ ⁢ ⁢ pa 2 , to level the substrate near the edges of the substrate, and wherein Δp is an applied clamping pressure and a is an average distance between two protrusions.