SEMICONDUCTOR FABRICATION PROCESS USING ETCH STOP LAYER TO OPTIMIZE FORMATION OF SOURCE/DRAIN STRESSOR

摘要

A semiconductor fabrication process includes forming an etch stop layer (ESL) (109) overlying a buried oxide (BOX) layer (102) and an active semiconductor layer (105) overlying the ESL. A gate electrode (112) is formed overlying the active semiconductor layer. Source/drain regions of the active semiconductor layer are etched to expose the ESL. Source/drain stressors (130) are formed on the ESL where the source/drain stressors strain the transistor channel (115). Forming the ESL may include epitaxially growing a silicon germanium ESL having a thickness of approximately 30 nm or less. Preferably a ratio of the active semiconductor layer etch rate to the ESL etch rate exceeds 10:1. A wet etch using a solution of NH4OH:H2O heated to a temperature of approximately 75‹ C may be used to etch the source/drain regions. The ESL may be silicon germanium having a first percentage of germanium. The source/drain stressors may be silicon germanium having a second percentage of germanium for P-type transistors, and they may be silicon carbon for N-type transistors. ® KIPO & WIPO 2009