Patent ID: 9059233
Filing Date: 2015-06-16
Classification: H01L

Abstract:
1. A method comprising: forming a semiconductor layer on a semiconductor substrate, said semiconductor substrate comprising a first semiconductor material and said semiconductor layer comprising a second semiconductor material different from said first semiconductor material; forming a mask layer on said semiconductor layer; patterning an opening in said mask layer, said opening having a first sidewall and a second sidewall opposite said first sidewall, said first sidewall having a planar contour and said second sidewall having a saw-tooth contour; performing a first etch process to extend said opening through said semiconductor layer and into said semiconductor substrate; and performing a second etch process to expand a lower portion of said opening within said semiconductor substrate, said second etch process comprising a crystallographic etch process that etches said first sidewall and said second sidewall within said semiconductor substrate at different rates such that an asymmetric trench is formed within said semiconductor substrate below said semiconductor layer.