US Patent Issued to ZEON on Sept. 23 for "Copolymer, positive resist composition, and method of forming resist pattern" (Japanese Inventor)

ALEXANDRIA, Va., Sept. 23 -- United States Patent no. 12,422,753, issued on Sept. 23, was assigned to ZEON Corp. (Tokyo).

"Copolymer, positive resist composition, and method of forming resist pattern" was invented by Manabu Hoshino (Tokyo).

According to the abstract* released by the U.S. Patent & Trademark Office: "A copolymer includes a monomer unit (A) represented by formula (I), shown below, and a monomer unit (B) represented by formula (II), shown below, and has a weight-average molecular weight of 230,000 or more. In the formulae, L is a single bond or a divalent linking group, Ar is an optionally substituted aromatic ring group, R1 is an alkyl group, R2 is hydrogen, an alkyl group, a halogen atom, a haloalkyl group, a hydroxy group,...