Patent ID: 8728906
Filing Date: 2014-05-20
Classification: H01L

Abstract:
1. A method comprising: forming a pad oxide layer over a semiconductor substrate; forming a hard mask over the pad oxide layer; forming a mandrel layer over the hard mask; performing a first lithography process to pattern the mandrel layer and to form a plurality of mandrels; forming a spacer layer, wherein the spacer layer comprises top portions over the mandrels, and sidewall portions on sidewalls of the mandrels; patterning the spacer layer to leave the sidewall portions of the spacer layer; etching the hard mask and the pad oxide layer to form hard mask patterns and pad oxide patterns, wherein the step of etching is performed using the sidewall portions of the spacer layer as an etching mask; removing the sidewall portions of the spacer layer; filling spaces between the hard mask patterns and the pad oxide patterns with a dielectric material; removing the hard mask patterns and the pad oxide patterns; and performing an epitaxy to grow a semiconductor material in spaces left by the removed hard mask patterns and the pad oxide patterns.