Nitrogen based implants for defect reduction in strained silicon

Abstract

A transistor is fabricated upon a semiconductor substrate, where the yield strength or elasticity of the substrate is enhanced or otherwise adapted. A strain inducing layer is formed over the transistor to apply a strain thereto to alter transistor operating characteristics, and more particularly to enhance the mobility of carriers within the transistor. Enhancing carrier mobility allows transistor dimensions to be reduced while also allowing the transistor to operate as desired. However, high strain and temperature associated with fabricating the transistor result in deleterious plastic deformation. The yield strength of the silicon substrate is therefore adapted by incorporating nitrogen into the substrate, and more particularly into source/drain extension regions and/or source/drain regions of the transistor. The nitrogen can be readily incorporated during transistor fabrication by adding it as part of source/drain extension region formation and/or source/drain region formation. The enhanced yield strength of the substrate mitigates plastic deformation of the transistor due to the strain inducing layer.