Patent ID: 9159785
Filing Date: 2015-10-13
Classification: H01L

Abstract:
1. A method for forming a buried layer, comprising: providing a semiconductor substrate including a hard mask layer thereon, wherein the hard mask layer has a plurality of through-openings; forming a plurality of deep trenches in the semiconductor substrate using the hard mask layer as a mask; doping a bottom of each of the plurality of deep trenches in the semiconductor substrate to form a plurality of heavily-doped regions; connecting one or more of the plurality of heavily-doped regions to form the buried layer in the semiconductor substrate; after the buried layer is formed, forming an oxide layer on an inner surface of sidewalls and a bottom of each of the plurality of deep trenches; and filling the plurality of deep trenches with a filling material on sidewalls and a bottom of the oxide layer in each deep trench to form isolation structures between adjacent active regions in the semiconductor substrate.