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A method of a bulk tri-gate transistor having stained enhanced mobility and its method of fabrication. The present invention is a nonplanar transistor having a strained enhanced mobility and its method of fabrication. The transistor has a semiconductor body formed on a semiconductor substrate wherei

A method of a bulk tri-gate transistor having stained enhanced mobility and its method of fabrication. The present invention is a nonplanar transistor having a strained enhanced mobility and its method of fabrication. The transistor has a semiconductor body formed on a semiconductor substrate wherein the semiconductor body has a top surface on laterally opposite sidewalls. A semiconductor capping layer is formed on the top surface and on the sidewalls of the semiconductor body. A gate dielectric layer is formed on the semiconductor capping layer on the top surface of a semiconductor body and is formed on the capping layer on the sidewalls of the semiconductor body. A gate electrode having a pair of laterally opposite sidewalls is formed on and around the gate dielectric layer. A pair of source/drain regions are formed in the semiconductor body on opposite sides of the gate electrode.

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We claim: 1. A semiconductor device comprising: a semiconductor body on an active region of a bulk semiconductor substrate, said semiconductor body having a top surface and laterally opposite sidewalls; an isolation region on said bulk semiconductor substrate, said isolation region adjacent to said

We claim: 1. A semiconductor device comprising: a semiconductor body on an active region of a bulk semiconductor substrate, said semiconductor body having a top surface and laterally opposite sidewalls; an isolation region on said bulk semiconductor substrate, said isolation region adjacent to said active region; a semiconductor capping layer formed on the top surface and on the sidewalls of said semiconductor body, wherein said semiconductor capping layer is formed thicker on the top surface of said silicon germanium body than on the sidewalls of said semiconductor body; a gate dielectric layer formed on said semiconductor capping layer on said top surface and on said sidewalls of said semiconductor body; a gate electrode having a pair of laterally opposite sidewalls formed on and around said gate dielectric layer; and a pair of source/drain regions formed in said semiconductor body on opposite sides of said gate electrode. 2. The semiconductor device of claim 1 wherein said semiconductor capping layer has a tensile stress. 3. The semiconductor device of claim 2 wherein said semiconductor capping layer has greater tensile stress on the sidewalls of said semiconductor body than on the top surface of said semiconductor body. 4. The semiconductor device of claim 2 wherein said source/drain regions are n type conductivity. 5. The semiconductor device of claim 1 wherein said bulk semiconductor substrate is a silicon substrate, wherein said semiconductor body is a silicon germanium alloy and wherein said semiconductor capping layer is a silicon film. 6. The semiconductor device of claim 1 wherein said semiconductor capping layer has a compressive stress. 7. The semiconductor device of claim 6 wherein said semiconductor capping layer has a greater compressive stress on the sidewalls than on the top surface of said semiconductor body. 8. A semiconductor device comprising: a silicon germanium body formed on an active region of a bulk silicon monocrystalline substrate, said silicon germanium body having a top surface and a pair of laterally opposite sidewalls; an isolation region on said bulk silicon monocrystalline substrate, said isolation region adjacent to said active region and adjacent to a portion of said silicon germanium body; a silicon film formed on said top surface and on said sidewalls of said silicon germanium body, wherein said silicon film is formed thicker on the top surface of said silicon germanium body than on the sidewalls of said silicon germanium body; a gate dielectric layer formed on said silicon film on said top surface of said silicon germanium body and on said silicon film on said sidewalls of said silicon germanium body; a gate electrode having a pair of laterally opposite sidewalls formed on and around said gate dielectric layer; and a pair of source/drain regions formed in said silicon germanium body on opposite sides of said gate electrode. 9. The semiconductor device of claim 8 wherein said silicon film has a thickness between 50-300 Å. 10. The semiconductor device of claim 8 wherein said silicon germanium alloy comprises between 5-40% germanium. 11. The semiconductor device of claim 10 wherein said silicon germanium alloy comprises approximately 15-25% germanium. 12. The semiconductor device of claim 8 wherein said source/drain regions are n type conductivity. 13. A semiconductor device comprising: a silicon-carbon alloy body formed on an active region of a silicon monocrystalline substrate, said silicon carbon alloy body having a top surface and a pair of laterally opposite sidewalls; an isolation region on said bulk semiconductor substrate, said isolation region adjacent to said active region and adjacent to a portion of said silicon-carbon alloy body; a silicon film formed on said top surface and on said sidewalls of said silicon carbon alloy body, wherein said silicon film is formed thicker on the top surface of said silicon carbon alloy body than on the sidewalls of said silicon germanium body; a gate dielectric layer formed on said silicon film on said top surface of said silicon-carbon body and on said silicon film on said sidewalls of said silicon-carbon alloy body; a gate electrode having a pair of laterally opposite sidewalls formed on and around said gate dielectric layer; and a pair of source/drain regions formed in said silicon carbon-alloy body on opposite sides of said gate electrode. 14. The semiconductor device of claim 13 wherein said silicon film is formed to a thickness between 50-300 Å. 15. The semiconductor device of claim 14 wherein said silicon film has a thickness between 50-300 Å. 16. The semiconductor device of claim 13 wherein said source/drain regions are p type conductivity. 17. A semiconductor device comprising: a silicon germanium body formed on a silicon monocrystalline substrate, said silicon germanium body having a top surface and a pair of laterally opposite sidewalls; a silicon film formed on said top surface and on said sidewalls of said silicon germanium body, wherein said silicon film is formed thicker on the top surface of said silicon germanium body than on the sidewalls of said silicon germanium body; a gate dielectric layer formed on said silicon film on said top surface of said silicon germanium body and on said silicon film on said sidewalls of said silicon germanium body; a gate electrode having a pair of laterally opposite sidewalls formed on and around said gate dielectric layer; and a pair of source/drain regions formed in said silicon germanium body on opposite sides of said gate electrode. 18. A semiconductor device comprising: a semiconductor body on a bulk semiconductor substrate, said semiconductor body having a top surface and laterally opposite sidewalls, wherein said semiconductor body is comprised of a material which has a different lattice constant than said bulk semiconductor substrate; semiconductor capping layer formed on the top surface and on the sidewalls of said semiconductor body, wherein said semiconductor capping layer comprises a material which has a different lattice constant than said semiconductor body and wherein said semiconductor capping layer is formed thicker on the top surface of said semiconductor body than on the sidewalls of said semiconductor body; a gate dielectric layer formed on said semiconductor capping layer on said top surface and on said sidewalls of said semiconductor body; a gate electrode having a pair of laterally opposite sidewalls formed on and around said gate dielectric layer; and a pair of source/drain regions formed in said semiconductor body on opposite sides of said gate electrode. 19. The semiconductor device of claim 18, wherein said semiconductor body comprises a semiconductor material having a lattice constant that is larger than the lattice constant of said bulk semiconductor substrate. 20. The semiconductor device of claim 18, wherein said semiconductor body comprises a semiconductor material having a lattice constant that is smaller than the lattice constant of said bulk semiconductor substrate. 21. The semiconductor device of claim 18, wherein said semiconductor capping layer comprises a semiconductor material having a lattice constant that is larger than the lattice constant of said semiconductor body. 22. The semiconductor device of claim 18, wherein said semiconductor capping layer comprises a semiconductor material having a lattice constant that is smaller than the lattice constant of said semiconductor body. 23. The semiconductor device of claim 18, wherein said bulk semiconductor substrate is a silicon substrate, wherein said semiconductor body is a silicon germanium alloy and wherein said semiconductor capping layer is a silicon film. 24. The semiconductor device of claim 18, wherein said bulk semiconductor substrate is a silicon substrate, wherein said semiconductor body is a silicon-carbon alloy body, and wherein said semiconductor capping layer is a silicon capping layer. 25. A semiconductor device comprising: a semiconductor body on a bulk semiconductor substrate, said semiconductor body having a top surface and laterally opposite sidewalls; a semiconductor capping layer on the top surface and on the sidewalls of said semiconductor body, wherein said semiconductor capping layer is thicker on the top surface of said semiconductor body than on the sidewalls of said semiconductor body; a gate dielectric layer on said semiconductor capping layer on said top surface and on said sidewalls of said semiconductor body; a gate electrode having a pair of laterally opposite sidewalls on and around said gate dielectric layer; and a pair of source/drain regions in said semiconductor body on opposite sides of said gate electrode.