US Patent Issued to SHIN-ETSU CHEMICAL on April 29 for "Manufacturing method of photomask, and photomask blank" (Japanese Inventor)

ALEXANDRIA, Va., June 9 -- United States Patent no. 12,288,688, issued on April 29, was assigned to SHIN-ETSU CHEMICAL Co. LTD. (Tokyo).

"Manufacturing method of photomask, and photomask blank" was invented by Kouhei Sasamoto (Joetsu, Japan).

According to the abstract* released by the U.S. Patent & Trademark Office: "A photomask is manufactured from a photomask blank including a transparent substrate, a first inorganic film which comprises silicon and is free of chromium, and a second inorganic film which comprises chromium and is free of silicon, and is in contact with the first inorganic film by a method including steps of forming a pattern of the second inorganic film by fluorine-based dry etching with using a resist pattern, and formi...