Patent ID: 6818938
Filing Date: 2004-11-16
Classification: H01L

Abstract:
A MOS transistor formed on a semiconductor material of a first conductivity type, the transistor comprising:a layer of composite material of the first conductivity type formed on the semiconductor material, the layer of composite material including silicon, germanium, and carbon, the layer of composite material including a plurality of layers, the plurality of layers including a first layer that has silicon and carbon, a second layer formed over and contacting the first layer, and a third layer formed over and contacting the second layer, the second layer having silicon and germanium and being substantially free of carbon, the third layer having silicon, germanium, and carbon atoms; spaced apart source and drain regions of a second conductivity type formed in the layer of composite material; a channel region located between the source and drain regions; an insulation layer formed on the layer of material; and a gate formed on the insulation layer over the channel region.