Phase angle modulation of PSM by chemical treatment method

摘要

A method for modulating the phase angle of a phase shift mask employed in deep ultraviolet (DUV) photolithography. There is provided a quartz substrate within which may be formed an engraved pattern, and upon which is formed a patterned phase shift layer. The phase angle of the phase shift layer upon the quartz substrate may be incrementally increased or decreased by subtractive etching of the phase shift layer and quartz substrate of the phase shift mask in an alkaline solution at a selected temperature and concentration for a period of time.