Photomask and pattern formation method using the same

Abstract

A photomask includes: a transparent substrate having a transparent property against exposing light; a first light-shielding pattern formed on the transparent substrate and having a first dimension; a second light-shielding pattern formed on the transparent substrate and having a second dimension larger than the first dimension; and an opening provided in part of the transparent substrate where the first light-shielding pattern and the second light-shielding pattern are not formed. The first light-shielding pattern includes a first semi-light-shielding portion and an auxiliary pattern which is arranged within the first semi-light-shielding portion and allows the exposing light to pass through in an opposite phase with respect to the first semi-light-shielding portion. The second light-shielding pattern includes a second semi-light-shielding portion and a light-shielding portion which does not substantially allow the exposing light to pass through.

1 - 17 . (canceled) 
     
     
         18 . A photomask comprising:
 a mask pattern formed on a transparent substrate having a transparent property against exposing light, wherein:   the mask pattern includes a semi-light-shielding portion which allows the exposing light to partially pass through, and a light-shielding portion which does not substantially allow the exposing light to pass through,   an opening surrounding the mask pattern is provided in the transparent substrate,   the light-shielding portion is arranged on the edge of the semi-light-shielding portion, and   the semi-light-shielding portion allows the exposing light to pass through in a substantially identical phase with respect to the opening.   
     
     
         19 . The photomask of  claim 18 , wherein the light-shielding portion is disconnected at a corner of the mask pattern. 
     
     
         20 . The photomask of  claim 19 , wherein each disconnected part of the light-shielding portion has a length shorter than a corresponding side of the mask pattern. 
     
     
         21 . The photomask of  claim 18 , wherein the light-shielding portion has a width set to be not less than a minimum width with which a resolution required for transferring the mask pattern is obtained. 
     
     
         22 . The photomask of  claim 18 , wherein the light-shielding portion has a width set to be not more than a maximum width with which an unexposed region is not formed. 
     
     
         23 . The photomask of  claim 21 , wherein:
 the photomask is designed for a specific reduction projection optical system, and is included in such a system along with an exposure apparatus, and   the light-shielding portion of the photomask has a width not less than (0.17×λ/NA)×M, where λ is a wavelength of the exposing light, NA is numerical aperture of a reduction projection optical system of an aligner and M is a reduction ratio of the reduction projection optical system.   
     
     
         24 . The photomask of  claim 22 , wherein:
 the photomask is designed for a specific reduction projection optical system, and is included in such a system along with an exposure apparatus, and   the light-shielding portion of the photomask has a width not mote than (1.72×λ/NA)×M, where λ is a wavelength of the exposing light, NA is numerical aperture of a reduction projection optical system of an aligner and M is a reduction ratio of the reduction projection optical system.   
     
     
         25 . The photomask of  claim 18 , wherein in the mask pattern, a side face of a semi-light-shielding film serving as the semi-light-shielding portion, and a side face of a light-shielding film serving as the light-shielding portion are substantially flush with each other. 
     
     
         26 . The photomask of  claim 18 , wherein in the mask pattern, a side face of a semi-light-shielding film serving as the semi-light-shielding portion is covered with a light-shielding film serving as the light-shielding portion. 
     
     
         27 . The photomask of  claim 25 , wherein the light-shielding film is in contact with the semi-light-shielding film only. 
     
     
         28 . The photomask of  claim 25 , wherein the light-shielding film is in contact with both of the transparent substrate and the semi-light-shielding film. 
     
     
         29 . A pattern formation method using the photomask of  claim 18 , the method comprising steps of:
 (a) forming a resist film on a substrate;   (b) irradiating the resist film with the exposing light through the photomask; and   (c) patterning the resist film by developing the resist film having been irradiated with the exposing light.   
     
     
         30 . The pattern formation method of  claim 29 , wherein ArF excimer laser is used as an exposing light source in the step (b). 
     
     
         31 . The pattern formation method of  claim 30 , wherein immersion exposure process is employed in the step (b). 
     
     
         32 . The pattern formation method of  claim 31 , wherein the step (a) includes coating of the resist film with a top coat.