ALEXANDRIA, Va., Nov. 18 -- United States Patent no. 12,474,635, issued on Nov. 18, was assigned to United Microelectronics Corp. (Hsinchu, Taiwan).
"Photomask structure" was invented by Chia-Chen Sun (Kaohsiung, Taiwan), En-Chiuan Liou (Tainan, Taiwan) and Song-Yi Lin (Tainan, Taiwan).
According to the abstract* released by the U.S. Patent & Trademark Office: "A photomask structure having a first region and a second region is provided. The layout pattern density of the first region is smaller than the layout pattern density of the second region. The photomask structure includes a first layout pattern, a second layout pattern, and first assist patterns. The first layout pattern is located in the first region and the second region. The sec...