Systems and methods for lithography masks

摘要

Structure of mask blanks and masks, and methods of making masks are disclosed. The new mask blank and mask comprise a tripe etching stop layer to prevent damages to the quartz substrate when the process goes through etching steps three times. The triple etching stop layer may comprise a first sub-layer of tantalum containing nitrogen (TaN), a second sub-layer of tantalum containing oxygen (TaO), and a third sub-layer of TaN. Alternatively, the triple etching stop layer may comprise a first sub-layer of SiON material, a second sub-layer of TaO material, and a third sub-layer of SiON material. Another alternative may be one layer of low etching rate MoxSiyONz material which can prevent damages to the quartz substrate when the process goes through etching steps three times. The island mask is defined on the mask blank by using various optical proximity correction rules.

主权项

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.