Methods to fabricate MOSFET devices using a selective deposition process
In one embodiment, a method for forming a silicon-based material on a substrate having dielectric materials and source/drain regions thereon within a process chamber is provided which includes exposing the substrate to a first process gas comprising silane, methylsilane, a first etchant, and hydrogen gas to deposit a first silicon-containing layer thereon. The first silicon-containing layer may be selectively deposited on the source/drain regions of the substrate while the first silicon-containing layer may be etched away on the surface of the dielectric materials of the substrate. Subsequently, the process further provides exposing the substrate to a second process gas comprising dichlorosilane and a second etchant to deposit a second silicon-containing layer selectively over the surface of the first silicon-containing layer on the substrate.
1. A method for forming a silicon-based material on a substrate surface, comprising:
exposing a substrate to a first process gas comprising silane, a germanium source, a carbon source, a first etchant comprising HCl, and a carrier gas to selectively and epitaxially deposit a first silicon-containing layer on the substrate at a pressure within a range from about 0.5 Torr to about 50 Torr, wherein the first silicon-containing layer comprises a graded carbon concentration and has interstitial sites within a crystalline lattice and comprises about 3 at % or less of carbon within the interstitial sites;
exposing the substrate to a second process gas comprising dichlorosilane and a second etchant comprising HCl to selectively and epitaxially deposit a second silicon-containing layer on the first silicon-containing layer; and
annealing the substrate to incorporate at least a portion of the carbon into substitutional sites of the crystalline lattice within the first silicon-containing layer.
2. The method of claim 1 , wherein the substrate is exposed to the first process gas comprising:
the silane at a flow rate within a range from about 20 sccm to about 400 sccm;
the carbon source at a flow rate within a range from about 0.3 sccm to about 5 sccm;
the first etchant at a flow rate within a range from about 30 sccm to about 500 sccm; and
the carrier gas at a flow rate within a range from about 10 slm to about 30 slm.
3. The method of claim 2 , wherein the first silicon-containing layer is deposited on the substrate within a processing chamber having an internal pressure within a range from about 1 Torr to about 10 Torr.
4. The method of claim 1 , wherein the first process gas further comprises a dopant precursor.
5. The method of claim 4 , wherein the dopant precursor is selected from the group consisting of diborane, arsine, phosphine, and derivatives thereof.
6. The method of claim 5 , wherein the first silicon-containing layer comprises a graded dopant concentration.
7. The method of claim 1 , wherein the first silicon-containing layer has a boron concentration within a range from about 5×10 19 atoms/cm 3 to about 1×10 20 atoms/cm 3 .
8. The method of claim 1 , wherein the first silicon-containing layer has a boron concentration greater than 1×10 20 atoms/cm 3 .
9. The method of claim 8 , wherein the boron concentration is about 2×10 20 atoms/cm 3 or greater.
10. The method of claim 1 , wherein the second silicon-containing layer has a boron concentration greater than 1×10 20 atoms/cm 3 .
11. The method of claim 10 , wherein the boron concentration is about 2×10 20 atoms/cm 3 or greater.
12. The method of claim 1 , wherein the carbon source comprises methylsilane.
13. A method for forming a silicon-based material on a substrate surface, comprising:
exposing a substrate to a first process gas comprising silane, a carbon source, a germanium source, a first etchant comprising HCl, and a carrier gas to selectively and epitaxially deposit a first silicon-containing layer on the substrate at a pressure within a range from about 0.5 Torr to about 50 Torr, wherein the first silicon-containing layer has interstitial sites within a crystalline lattice and comprises about 3 at % or less of carbon within the interstitial sites;
exposing the substrate to a second process gas comprising dichlorosilane and a second etchant comprising HCl to selectively and epitaxially deposit a second silicon-containing layer on the first silicon-containing layer; and
annealing the substrate to incorporate at least a portion of the carbon into substitutional sites of the crystalline lattice within the first silicon-containing layer.
14. The method of claim 13 , wherein the carbon source is methylsilane.
15. The method of claim 13 , wherein the first silicon-containing layer or the second silicon-containing layer has a boron concentration greater than 1×10 20 atoms/cm 3 .
16. The method of claim 15 , wherein the boron concentration is about 2×10 20 atoms/cm 3 or higher.