US Patent Issued to HOYA on Jan. 20 for "Mask blank, phase shift mask, and method of manufacturing semiconductor device" (Japanese Inventors)

ALEXANDRIA, Va., Jan. 20 -- United States Patent no. 12,529,953, issued on Jan. 20, was assigned to HOYA Corp. (Tokyo).

"Mask blank, phase shift mask, and method of manufacturing semiconductor device" was invented by Hitoshi Maeda (Tokyo) and Osamu Nozawa (Tokyo).

According to the abstract* released by the U.S. Patent & Trademark Office: "A mask blank comprises: a light-transmissive substrate; and a phase shift film formed on the light-transmissive substrate, in which the phase shift film includes a lower layer containing hafnium and oxygen and an upper layer formed on the lower layer and containing silicon, oxygen, and nitrogen, a total content of hafnium and oxygen in the lower layer is 95 atom % or more, and a content of nitrogen in th...