Fabrication of strained Si nMOSFET transistors on thin buffer layers with selective and non-selective epitaxial growth techniques

Strained Si nMOSFET transistors were fabricated on thin SiGe/strained silicon buffer layers, using a standard chemical vapour deposition (CVD) technique. The layers have been grown in a non-selective way (on unpatterned wafers), others with a selective epitaxial deposition (on patterned wafers, after the isolation module). The transistors in both types of layers show a significant transconductance and mobility improvement compared to the reference devices. The process adjustments needed in the isolation module for non-selective SiGe/strained Si transistors are described, and the electrical evaluation of the isolation module for non-selective wafers shows the influence of several processing steps on device performance.