Phase shift mask and method for manufacturing the same, and method for manufacturing integrated circuit

Abstract

A phase shift mask is provided which includes: a substrate that is transparent to irradiation light, a shielding region formed on the substrate and in which a line pattern is formed, and a first transparent region and a second transparent region located on respective opposite sides of the shielding region on the substrate, wherein a phase shifter is formed under the first transparent region, and the phase shifter has a side wall including an outward protruding bent portion. The phase shifter can be formed by, for example, irradiating and scanning a predetermined region of the substrate with femtosecond pulse laser light applied from above the substrate.

What is claimed is: 
     
         1 . A method for manufacturing a phase shift mask, comprising:
 forming a shielding region with a line pattern on a substrate that is transparent to irradiation light, and   irradiating and scanning a first transparent region located on one side of the shielding region with femtosecond pulse laser light applied from above the substrate, to form a phase shifter which has a side wall including an outward protruding bent portion.   
     
     
         2 . The method for manufacturing the phase shift mask according to  claim 1 , wherein the scanning with the femtosecond pulse laser light is carried out with maintaining a focal depth of the femtosecond pulse laser light. 
     
     
         3 . The method for manufacturing the phase shift mask according to  claim 2 , wherein the focal depth is set equal to λ/(4(n−1)), wherein λ is the wavelength of irradiation light and n is the refractive index of the substrate, from a surface of the substrate. 
     
     
         4 . The method for manufacturing the phase shift mask according to  claim 3 , wherein a boundary between the first transparent region and the shielding region as viewed from the top surface of the substrate is used as a contour of a scan region for the femtosecond pulse laser light. 
     
     
         5 . The method for manufacturing the phase shift mask according to  claim 1 , wherein a trench is formed as the phase shifter by engraving the trench on a surface of the substrate. 
     
     
         6 . The method for manufacturing the phase shift mask according to  claim 5 , wherein an irradiation condition for the femtosecond pulse laser light is adjusted in such a manner that the trench has a depth of λ/(2(n−1)), wherein λ is the wavelength of irradiation light and n is the refractive index of the substrate. 
     
     
         7 . The method for manufacturing the phase shift mask according to  claim 1 , wherein a cavity is formed inside the substrate as the phase shifter. 
     
     
         8 . The method for manufacturing the phase shift mask according to  claim 7 , wherein the irradiation condition for the femtosecond pulse laser light is adjusted in such a manner that the cavity has a height of λ/(2(n−1)), wherein λ is the wavelength of irradiation light and n is the refractive index of the substrate. 
     
     
         9 . The method for manufacturing the phase shift mask according to  claim 1 , further comprising:
 depositing a shielding conductive film on the substrate; and   patterning the shielding conductive film to form the shielding region.   
     
     
         10 . A method for manufacturing an integrated circuit, comprising using a phase shift mask that comprises:
 a substrate that is transparent to irradiation light,   a shielding region formed on the substrate and in which a line pattern is formed, and   a first transparent region and a second transparent region located on respective opposite sides of the shielding region on the substrate,
 wherein a phase shifter is formed under the first transparent region, and the phase shifter has a side wall including an outward protruding bent portion; 
   wherein said phase shift mask is used to transfer the line pattern formed on the phase shift mask.