Claims
- 1. A method for forming an alloy layer of silicon germanium carbon on a silicon containing substrate comprising the steps of:placing a wafer having a single crystalline silicon containing surface into a ultra-high vacuum (UHV) chemical vapor deposition (CVD) chamber; heating said silicon containing surface to a temperature in the range from about 350°-850° C., and flowing a silicon containing gas, a germanium containing gas and a carbon containing gas over said silicon containing surface whereby said silicon germanium carbon layer having an oxygen content of less than 1×1017 atoms/cc is formed, said carbon containing gas is selected from the group of molecules containing unsaturated double or triple carbon-carbon bonds.
- 2. The method of claim 1 wherein said UHV CVD chamber has a base pressure below 10−8 Torr.
- 3. The method of claim 1 wherein said carbon containing gas includes gas molecules having at least two carbon atoms.
- 4. The method of claim 1 wherein said carbon containing gas is selected from the group consisting of ethylene, acetylene, propylene, butylene, pentene and mixtures thereof.
- 5. The method of claim 1 wherein said flowing gas is at a pressure in the range from about 1 to 50 millitorr.
- 6. The method of claim 1 wherein flowing gases contain less than 1 ppm of contaminant gases containing oxygen.
- 7. The method of claim 1 wherein said carbon from said carbon containing gas is incorporated into said alloy crystal lattice substitutionally whereby said carbon is electrically active.
- 8. The method of claim 1 wherein said germanium from said germanium containing gas is incorporated into said alloy crystal lattice substitutionally whereby said germanium is electrically active.
- 9. The method of claim 1 wherein said carbon from said carbon containing gas and germanium from said germanium containing gas are incorporated into said alloy crystal lattice substitutionally whereby both said carbon and said germanium are electrically active.
- 10. The method of claim 1 wherein said step of placing a wafer includes placing a plurality of wafers into said UHV CVD chamber.
- 11. The method of claim 1 wherein said step of flowing includes flowing a dopant containing gas selected from the group consisting of diborane, phosphine, arsine and mixtures thereof.
- 12. The method of claim 1 wherein said silicon germanium carbon alloy is single crystalline.
- 13. The method of claim 1 wherein said silicon germanium carbon alloy is polycrystalline.
CROSS-REFERENCE TO RELATED APPLICATION
Cross-reference is made to U.S. patent application Ser. No. 09/774,126 filed Jan. 30, 2001 by Chu et al. entitled “Incorporation of Carbon in Silicon/Silicon Germanium epitaxial layer to Enhance Yield for Si—Ge bipolar technology” which is directed to a method of fabricating a SiGe bipolar transistor including carbon in the collector region as well as the SiGe base region and which is assigned to the assignee herein and incorporated herein by reference.
US Referenced Citations (4)
Non-Patent Literature Citations (3)
Entry |
Todd et al, growth of heterroepitaxail SiGeC alloys on silicon using novel chemistry., Appl. Physc. letts 67 9() Aug. 28, 1995.* |
E. Kasper et al., “Growth of 100 GHz SiGe-Heterobipolar Transistor (HBT) Structures,” Jpn J Appl Phys, vol. 33 Pt. 1, No. 4B, Apr. 1994, pp. 2415-2418. |
H.J. Osten et al., in the paper entitled “Carbon Doped SiGe Heterojunction Bipolar Transistors for High Frequency Applications,” IEEE BCTM 7.1, 1999, pp. 109-116. |