Enhanced mobility MOSFET device and method

A process for forming an enhanced mobility semiconductor MOSFET structure including the steps of:

• forming a channel layer comprising a Si.sub.1-x C.sub.x alloy on a monocrystalline silicon layer of a first conductivity type, wherein carbon is present in the channel layer in substitutional lattice sites so that the channel layer is under tensile stress, and wherein the channel layer has a bandgap narrower than the monocrystalline silicon layer;
• forming an epitaxial silicon layer on the channel layer;
• forming a source region of a second conductivity type extending through the epitaxial silicon layer and at least into the channel layer;
• forming a drain region of the second conductivity type extending through the epitaxial silicon layer and at least into the channel layer, wherein part of the channel layer separates the source region from the drain region;
• forming a gate dielectric layer on the epitaxial silicon layer between the source region and the drain region;
• and
• forming a gate electrode on the gate dielectric layer.

A method for forming an enhanced mobility semiconductor device comprising the steps of:

• providing a monocrystalline silicon layer of a first conductivity type;
• forming a carrier transport region on the monocrystalline silicon layer, wherein the carrier transport region comprises an alloy of silicon and a second material, and wherein the carrier transport region is under tensile stress, and wherein the carrier transport region has a bandgap narrower than the monocrystalline silicon layer;
• forming a source region of a second conductivity type extending into the carrier transport region;
• forming a drain region of the second conductivity type extending into the carrier transport region;
• and
• forming an electrically insulated control electrode over the carrier transport region, wherein the control electrode is disposed between the source region and the drain region.