Patent ID: 6773854
Filing Date: 2004-08-10
Classification: G03F,H01J

Abstract:
A method of producing a perforated mask having a desired pattern of openings for a projection of particle radiation onto a projection area, which comprises:cutting openings in a blank broadened in two dimensions; after the cutting, subjecting the blank to deformation forces leaving a distortion of an expected cut pattern; calculating the distortion in advance by determining values of an elasticity of adjacent cells of the mask with respect to longitudinal and shear stresses in a main plane of the mask on a model having the desired pattern of openings; calculating the vector field of the expected distortion by linking the elasticity values determined with the deformation forces with a FE calculation; selecting a pattern for cutting the blank, the pattern representing the desired pattern with a distortion being an inverse of the calculated distortion; determining geometric variables including a length and a direction of all edge sections of each of the openings and a cross-sectional area of each of the openings by measuring openings of each of the cells of at least a selected subset of cells of the model; and analytically determining the elasticity values of each selected cell from preselected functions containing, as a variable, statistical parameters derived from the determined geometric variables.