US 11,720,014 B2
Mask blank, phase shift mask, and method of manufacturing semiconductor device
Hitoshi Maeda, Tokyo (JP); Osamu Nozawa, Tokyo (JP); and Hiroaki Shishido, Tokyo (JP)
Assigned to HOYA CORPORATION, Tokyo (JP)
Appl. No. 17/428,821
Filed by HOYA CORPORATION, Tokyo (JP)
PCT Filed Feb. 6, 2020, PCT No. PCT/JP2020/004507
§ 371(c)(1), (2) Date Aug. 5, 2021,
PCT Pub. No. WO2020/166475, PCT Pub. Date Aug. 20, 2020.
Claims priority of application No. 2019-023891 (JP), filed on Feb. 13, 2019.
Prior Publication US 2022/0128898 A1, Apr. 28, 2022
Int. Cl. G03F 1/32 (2012.01); H01L 21/033 (2006.01)
CPC G03F 1/32 (2013.01) [H01L 21/0337 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A mask blank comprising a phase shift film on a transparent substrate,
wherein a transmittance of the phase shift film with respect to an exposure light of a KrF excimer laser is 2% or more, and
wherein the phase shift film is configured to transmit the exposure light so that transmitted light has a phase difference of 150 degrees or more and 210 degrees or less with respect to the exposure light transmitted through the air for a same distance as a thickness of the phase shift film;
wherein the phase shift film has a structure where a lower layer and an upper layer are stacked in order from a side of the transparent substrate;
wherein a refractive index nL of the lower layer at a wavelength of the exposure light and a refractive index nU of the upper layer at a wavelength of the exposure light satisfy a relation of nL>nU;
wherein an extinction coefficient kL of the lower layer at a wavelength of the exposure light and an extinction coefficient kU of the upper layer at a wavelength of the exposure light satisfy a relation of kL>kU; and
wherein a thickness dL of the lower layer and a thickness dU of the upper layer satisfy a relation of dL<dU.