Patent ID: 7678535
Filing Date: 2010-03-16
Classification: H01L

Abstract:
1. A method for fabricating a semiconductor device, comprising: forming a mask pattern over a substrate; etching a certain portion of the substrate using the mask pattern as an etch mask to form a first recess having sidewalls; forming a polymer-based layer over the sidewalls of the first recess and a top surface of the mask pattern, wherein the polymer-based layer is formed at the same time when the substrate is etched to form the first recess; etching the substrate beneath the first recess using the mask pattern and the polymer-based layer as an etch mask to form a second recess wider and more rounded than the first recess, the second recess and the first recess constituting a bulb-shaped recess; rounding top corners of the bulb-shaped recess; and forming a gate pattern over the bulb-shaped recess.