Patent ID: 7338736
Filing Date: 2008-03-04
Classification: G03F

Abstract:
1. A method of fabricating a phase shift mask, comprising: forming an opaque layer on a mask substrate; etching the opaque layer and the mask substrate to remove portions of said opaque layer from said mask substrate and form first, second and third discrete recesses in the mask substrate of equal depths at locations corresponding to a first transparent region, a second transparent region and a third transparent region of the phase shift mask, respectively, wherein the first, second and third discrete recesses are disposed side-by-side with the second recess located between the first and third recesses, and said etching of the opaque layer and the mask substrate is carried out such that a first contiguous portion of the opaque layer is left on the mask substrate as located between the first and second recesses, and a second contiguous portion of the opaque layer is left on the mask substrate as located between the second and third recesses; selectively and additionally etching the mask substrate such that the depth of the third recess at the third transparent region becomes different than the depth of the second recess at the second transparent region; and selectively removing only part of the first contiguous portion of the opaque layer to form a fourth transparent region, the removed part of the first contiguous portion lying directly adjacent the first transparent region such that a remaining part of the first contiguous portion of the opaque layer is left on the mask substrate as located between the fourth transparent region and the second recess.