Patent ID: 6682858
Filing Date: 2004-01-27
Classification: G03F

Abstract:
A mask set for forming holes in negative resist, comprising:a first transparent mask substrate having an X reference direction and a perpendicular Y reference direction; a second transparent mask substrate having said X reference direction and said perpendicular Y reference direction; a first mask formed in said first transparent mask substrate having a number of square first contact hole regions, wherein each of said square first contact hole regions consists of a first half region having a first thickness and a second half region having a second thickness, said first thickness and said second thickness are less than the thickness of said first transparent mask substrate, the boundaries between said first half region and said second half region in each of said square first contact hole regions are parallel to said X direction, said first thickness provides a 90Â° phase shift between light having a first wavelength passing through said first mask substrate and light having said first wavelength passing through said first half region, said second thickness provides a 270Â° phase shift between light having said first wavelength passing through said first mask substrate and light having said first wavelength passing through said second half region, and said first thickness and said second thickness provide a 180Â° phase shift between light having said first wavelength passing through said first half region and light having said first wavelength passing through said second half region; and a second mask formed in said second transparent mask substrate having a number of square second contact hole regions, wherein the number of said square first contact hole regions is equal to the number of said second square contact hole regions, each of said square second contact hole regions consists of a transparent third half region having a third thickness and a transparent fourth half region having a fourth thickness, the boundaries between said third half region and said fourth half region in each of said square second contact hole regions are parallel to said Y direction, said third thickness provides a 90Â° phase shift between light having said first wavelength passing through said second mask substrate and light having said first wavelength passing through said third half region, said fourth thickness provides a 270Â° phase shift between light having said first wavelength passing through said second mask substrate and light having said first wavelength passing through said fourth half region, and said third thickness and said fourth thickness provide a 180Â° phase shift between light having said first wavelength passing through said third half region and light having said first wavelength passing through said fourth half region.