Patent ID: 6232615
Filing Date: 2001-05-15
Classification: G03F

Abstract:
A lithographic projection apparatus comprising:a radiation system constructed and arranged to supply a projection beam of radiation;a mask table provided with a mask holder;a substrate table provided with a substrate holder;a projection system constructed and arranged to image an irradiated portion of a mask held by said mask holder onto a target portion of a substrate held by said substrate holder,the substrate holder comprising a plate having a face which is provided with a matrix arrangement of protrusions, each protrusion having an extremity remote from the face and being thus embodied that said extremities all lie within a single substantially flat plane at a height H above the face, the substrate holder further comprising a wall which protrudes from the face, substantially encloses the matrix arrangement, and has a substantially uniform height h above the face, whereby h<H, the face inside the wall being provided with at least one aperture extending through the plate and through which the area enclosed by the wall can be accessed, wherein:the matrix arrangement comprises a series of concentric circles whereby the protrusions are disposed along each circle at substantially regular arcuate intervals;the wall is substantially circular, and is concentric with said circles;the radial distance x between the wall and the circle nearest thereto satisfies the relationship 0.3<x/d<0.6, where d is the mutual radial separation of the two circles nearest the wall.