Photolithography method, photolithography mask blanks, and method of making
AssigneeCorning Incorporated
InventorsRichard S. Priestley, Daniel R. Sempolinski, Chunzhe C. Yu
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Abstract
The invention provides optical projection lithography methods, photolithography photomasks, and optical photolithography mask blanks for use in optical photolithography systems utilizing deep ultraviolet light (DUV) wavelengths below 300 nm, such as DUV projection lithography systems utilizing wavelengths in the 248 nm region and the 193 nm region. The invention provides improved production of lithography patterns by inhibiting polarization mode dispersion of lithography light utilizing low birefringence mask blanks and photomasks.
Claims14
A below three-hundred nanometer wavelength ultraviolet lithography light polarization mode dispersion inhibiting photolithography mask blank for producing lithography patterns while inhibiting polarization mode dispersion of transmitted ultraviolet lithography light, said polarization mode dispersion inhibiting mask blank comprised of a fused silica SiO2 glass wafer having a longest dimension length L, a thickness T, a mask blank x-axis, a mask blank y-axis, a mask blank z-axis, said length L lying in a plane defined by said mask blank x-axis and said mask blank y-axis, said thickness T normal to said plane defined by said mask blank x-axis and said mask blank y-axis, said thickness T parallel with said mask blank z-axis, said mask blank having a first refractive index nx in the direction along said mask blank x-axis and a second refractive index ny in the direction along said mask blank y-axis wherein |nx−ny|≦1 ppm.
A mask blank as claimed in 1, said mask blank has a maximum 193 nm transmission trans193xmax and a minimum 193 nm transmission trans193xmin along said mask blank x-axis, a maximum 193 nm transmission trans193ymax and a minimum 193 nm transmission trans193ymin along said mask blank y-axis, wherein (trans193max-trans193xmin) ≦1%, (trans193ymax-trans193ymin)≦1%.
A mask blank as claimed in 1 wherein |trans193xmax-trans193ymax|≦1%, and |trans193xmin-trans193ymin≦1%.
A mask blank as claimed in 1 said mask blank has a maximum 248 nm transmission trans248xmax and a minimum 248 nm transmission trans248xmin along said mask blank x-axis, a maximum 248 nm transmission trans248ymax and a minimum 248 nm transmission trans248ymin along said mask blank y-axis, wherein (trans248xmax−trans248xmin)≦1%, (trans248ymax−trans248ymin)≦1%.
A mask blank as claimed in 1 wherein said mask blank is free of inclusions 15 having a dimension greater than one micron.
A mask blank as claimed in 1 wherein said fused silica SiO2 glass consists essentially of Si and O.
A mask blank as claimed 1 in wherein said fused silica SiO2 glass contains less than 1 ppm C1.
A mask blank as claimed in 1 wherein said fused silica SiO2 glass contains less than 1500 ppm OH.
A mask blank as claimed in 1 wherein said fused silica SiO2 glass contains less than 3×1017 molecules of H2/cm3.
A mask blank as claimed in 1 wherein said mask blank has a chemical durability weight loss ≦0.453 mg/cm2 from submersed exposure to a 95° C. temperature 5% NaOH solution by weight in water for a length of 6 hours.
A mask blank as claimed in 1 wherein said fused silica SiO2 glass has an OH concentration which varies less than 200 ppm.
A mask blank as claimed in 1 wherein said fused silica SiO2 glass has a variation in chlorine content which varies less than 1 ppm C1.
A mask blank as claimed in 1 wherein said fused silica SiO2 glass has a S concentration ≦0.5 ppm S.
Dependencies are inferred from the claim text.