PHOTOMASK AND PATTERN FORMING METHOD USING THE SAME

摘要

PURPOSE: To enable the formation of effective dark parts and the formation of a translucent phase shift mask practically useful without increasing mask forming stages by constituting translucent phase shift parts and transparent parts with an optimum size combination. CONSTITUTION: Transparent pattern parts 5 are formed within the translucent phase shift regions 3 in the photomask including the translucent phase shift regions 3 formed in such a manner that the phase difference of the light passing the translucent regions attains about 180° with the phase difference of the light passing the transparent regions. A arrangement pitch 6 for the transparent patterns 5 is determined depending on the resolution characteristic of the projecting optical system to be used. The arrangement pitch P is expressed by equation P=α.λ/NA. In the equation, NA is the numerical aperture of a projecting lens; λ is an exposing wavelength; α denotes a coefft. The coefft. α is preferably empirically set at <=0.8. The width 7 of the transparent patterns 5 significantly affect the formation of the dark parts. The result thereof reveals that the optimum transmission pattern sizes exist according to the transmittance of the translucent shift parts 3.