Patent ID: 8329363
Filing Date: 2012-12-11
Classification: G03F

Abstract:
1. A method of forming halftone phase shift photomasks, the method comprising: preparing a blank photomask, the blank photomask including a shift layer, a light shielding layer, and a first resist layer stacked on a substrate; patterning the first resist layer to expose portions of the light shielding layer in a pattern area of the substrate and to cover portions of the light shielding layer in a blind area of the substrate by exposing and developing the first resist layer; selectively removing the light shielding layer using the patterned first resist layer as an etch mask to provide a light shielding pattern selectively exposing the shift layer; selectively removing the exposed shift layer using the light shielding pattern as an etch mask to form a half shift pattern that does not expose a surface of the substrate; forming a second resist layer on the light shielding pattern and the half shift pattern; patterning the second resist layer to provide a second resist pattern exposing the pattern area; removing a portion of the light shielding pattern in the pattern area of the substrate according to the second resist pattern to expose the half shift pattern; and partially removing the half shift pattern using a remaining portion of the light shielding pattern as an etch mask to form a second shift pattern in the pattern area of the substrate, the second shift pattern having a thickness that is smaller than a thickness of the first shift pattern on a blind area of the substrate.