Methods of making substitutionally carbon-doped crystalline Si-containing materials by chemical vapor deposition
Methods of making Si-containing films that contain relatively high levels of substitutional dopants involve chemical vapor deposition using trisilane and a dopant precursor. Extremely high levels of substitutional incorporation may be obtained, including crystalline silicon films that contain 2.4 atomic % or greater substitutional carbon. Substitutionally doped Si-containing films may be selectively deposited onto the crystalline surfaces of mixed substrates by introducing an etchant gas during deposition.
1. A method for depositing a single crystalline silicon film, comprising:
providing a substrate disposed within a chamber;
introducing trisilane and a carbon source to the chamber under chemical vapor deposition conditions, wherein trisilane is introduced to the chamber at a flow rate between about 5 mg per minute and about 2000 mg per minute; and
depositing a single crystalline silicon film onto the substrate at a deposition rate of at least about 5 nm per minute, the single crystalline silicon film as-deposited comprising at least about 1.0 atomic % substitutional carbon dopant, as determined by x-ray diffraction.
2. The method of claim 1 , wherein the single crystalline silicon film comprises 1.5 atomic % or greater substitutional carbon dopant.
3. The method of claim 1 , wherein the single crystalline silicon film comprises 2.4 atomic % or greater substitutional carbon dopant.
4. The method of claim 1 , comprising depositing the single crystalline silicon film onto the substrate at a deposition rate of at least about 10 nm per minute.
5. The method of claim 1 , comprising depositing the single crystalline silicon film onto the substrate at a deposition rate of at least about 20 nm per minute.
6. The method of claim 1 , wherein the substrate comprises single crystalline silicon.
7. The method of claim 1 , wherein the single crystalline silicon film comprises less than about 0.25 atomic % non-substitutional carbon.
8. The method of claim 1 , wherein the single crystalline silicon film comprises less than about 0.15 atomic % non-substitutional carbon.
9. The method of claim 1 , further comprising introducing a dopant precursor to the chamber.
10. The method of claim 9 , wherein the single crystalline silicon film comprises an electrically active dopant.
11. The method of claim 1 , wherein the chemical vapor deposition conditions comprise a temperature in the range of about 450° C. to about 600° C.
12. The method of claim 1 , wherein the chemical vapor deposition conditions comprise a temperature that is at about a transition temperature between substantially mass-transport controlled deposition conditions and substantially kinetically controlled deposition conditions.
13. The method of claim 1 , wherein the chemical vapor deposition conditions comprise a chamber pressure of at least about 500 mTorr.
14. The method of claim 1 , wherein the chemical vapor deposition conditions comprise a chamber pressure of at least about 20 Torr.
15. The method of claim 14 , wherein the chemical vapor deposition conditions comprise a chamber pressure in the range of about 20 Torr to about 200 Torr.
16. The method of claim 1 , wherein the carbon source is selected from the group consisting of monosilylmethane, disilylmethane, trisilylmethane, tetrasilylmethane, monomethyl silane, dimethyl silane and 1 ,3-disilabutane.
17. The method of claim 16 , wherein the carbon source is monomethylsilane.
18. The method of claim 1 , wherein the carbon source comprises a chlorosilylmethane of the formula (SiH 3-z Cl z ) x CH 4-x-y Cl y , where x is an integer in the range of 1 to 4 and where y and z are each independently zero or an integer in the range of 1 to 3, with the provisos that x+y≦4 and at least one of y and z is not zero.
19. The method of claim 1 , wherein the carbon source comprises an alkylhalosilane of the formula X a SiH b (C n H 2n+1 ) 4-a-b , where X is a halogen; n is 1 or 2; a is 1 or 2; b is 0,1 or2; and the sum of a and b is less than 4.
20. The method of claim 1 , wherein the single crystalline silicon film that is deposited onto the substrate forms a source region and a drain region.
21. A method for depositing a single crystalline silicon film, comprising:
providing a substrate disposed within a chamber;
introducing trisilane and a carbon source to the chamber under chemical vapor deposition conditions, wherein trisilane is introduced to the chamber at a flow rate between about 5 mg per minute and about 2000 mg per minute; and
depositing a single crystalline silicon film onto the substrate at a deposition rate of at least about 5 nm per minute, the single crystalline silicon film as-deposited comprising at least about 1.0 atomic % substitutional carbon dopant, as determined by x-ray diffraction, wherein the single crystalline silicon film forms a source region and a drain region and is tensile strained.
22. The method of claim 21 , wherein the substrate comprises a channel region positioned between the source region and the drain region.
23. The method of claim 22 , wherein the channel region is tensile strained.
24. The method of claim 20 , wherein the substrate comprises a gate electrode.
25. The method of claim 24 , further comprising depositing a polycrystalline silicon film over the gate electrode while depositing the single crystalline silicon film.
26. The method of claim 25 , further comprising etching the polycrystalline silicon film from over the gate electrode.
27. The method of claim 1 , wherein trisilane is introduced to the chamber at a flow rate between about 10 mg per minute and about 200 mg per minute.
28. The method of claim 1 , wherein trisilane is introduced to the chamber at a flow rate between about 100 mg per minute and about 500 mg per minute.
29. The method of claim 1 , wherein:
trisilane is introduced to the chamber at a flow rate between about 100 mg per minute and about 500 mg per minute; and
the chemical vapor deposition conditions comprise a chamber pressure of at least about 1 Torr.
30. The method of claim 1 , wherein:
trisilane is introduced to the chamber at a flow rate between about 100 mg per minute and about 500 mg per minute; and
the chemical vapor deposition conditions comprise a temperature in the range of about 450° C. to about 650° C.
31. The method of claim 1 , wherein:
trisilane is introduced to the chamber at a flow rate between about 100 mg per minute and about 500 mg per minute; and
the carbon source is introduced to the chamber at a flow rate such that a ratio of the carbon source flow rate to the trisilane flow rate is at least about 0.5 scc mg −1 .