Patent ID: 8969171
Filing Date: 2015-03-03
Classification: H01L

Abstract:
1. A method for forming a semiconductor device, comprising: providing a semiconductor-on-insulator (SOI) structure comprising an insulator layer, and a semiconductor layer over the insulator layer; forming at least one hard mask (HM) layer over the SOI structure, the at least one HM layer comprising a first VIM layer, and a second. HM layer over the first HM laver; forming a trench inside the at least one HM layer and the semiconductor layer, the trench having a bottom surface over the insulator layer and a side wall adjacent the at least one HM layer; depositing a spacer layer in the trench, the spacer layer comprising a bottom surface portion over the bottom surface of the trench, and a side wall portion along the side wall of the trench; etching the bottom surface portion of the spacer layer while the side wall portion of the spacer layer remains; etching the insulator layer to extend the trench into the insulator layer; and removing the second HM layer alter etching the insulator layer to extend the trench into the insulator layer.