Patent ID: 9057961
Filing Date: 2015-06-16
Classification: G03F

Abstract:
1. A method of making a mask, comprising: providing a mask blank having a substrate, a triple etching stop layer on the substrate, a shielding layer on the triple etching stop layer, a hard mask layer on the shielding layer, and a first positive chemical amplified resist (PCAR) layer on the hard mask layer; forming a ring trench of a first size around an island of a second size on the first PCAR layer, wherein the first size and the second size are obtained by a plurality of optical proximity correction (OPC) rules based on a final island mask size; extending the ring trench on the first PCAR layer to the hard mask layer, and further to the shielding layer; removing the first PCAR layer; forming a second photoresist layer covering the ring trench and on a surface of the island; removing a part of the second photoresist layer within the ring trench and the second photoresist layer outside the island; etching the hard mask layer separated from the island and uncovered by the second photoresist layer, and etching a part of a first sub-layer of the triple etching stop layer; etching the shielding layer separated from the island and uncovered by the second photoresist layer, and etching a part of a second sub-layer of the triple etching stop layer; removing the second photoresist layer around the island to uncover the hard mask layer on the island; and etching the hard mask layer on the island to form the final island mask.