Patent ID: 8338309
Filing Date: 2012-12-25
Classification: H01L

Abstract:
1. A method for forming a deep trench in a semiconductor device, comprising: forming a buffer layer over a substrate; forming a hard mask over the buffer layer, the hard mask comprising a nitride layer and an oxide layer; forming a hard mask pattern by etching the hard mask to thereby expose an upper portion of the substrate; forming a first trench in the exposed substrate by performing a first etching process using a gas containing bromide and a gas containing chloride; forming a second trench having a depth deeper than the first trench through a second etching process where the exposed substrate through a bottom portion of the first trench is etching using a gas containing sulfur and fluoride; forming a sidewall protective layer on an inner sidewall of the first and the second trenches; recessing the nitride layer; removing the oxide layer; forming a sidewall insulation layer along an inner surface of the first and second trenches after removing the oxide layer; and forming a device isolation layer to fill the first and the second trenches.