Method of forming optical images, diffration element for use with this method, apparatus for carrying out this method

摘要

An optical image is formed in a resist layer (5) by a number of sub-illuminations, in each of which an array of light valves (21-25) and a corresponding array of diffraction cells (91-95) are used to form a pattern of spots (111-115) in the resist layer according to a sub-image. Between the sub-illuminations, the resist layer is displaced relative to the arrays. Bright and well-defined spots are obtained by using diffraction cells having at least two amplitude levels and at least three phase levels.