Method of doped germanium formation

1. A method of processing a substrate, comprising:

exposing a substrate having an exposed silicon-germanium surface and an exposed dielectric surface to a pre-treatment process;

selectively depositing a boron-doped germanium layer on the exposed silicon-germanium surface, wherein the selectively depositing the boron-doped germanium layer on the exposed silicon-germanium surface comprises:

co-flowing a germanium source gas and a boron source gas;

stopping the flow of the germanium source gas while continuing to flow the boron source gas to deposit an amorphous boron-doped germanium layer on the exposed silicon-germanium surface and the exposed dielectric surface;

annealing the amorphous boron-doped germanium layer to recrystallize the amorphous boron-doped germanium layer formed on the exposed silicon-germanium surface while the amorphous boron-doped germanium layer formed on the exposed dielectric surface remains amorphous; and

etching the amorphous boron-doped germanium layer formed on the exposed dielectric surface; and

exposing the substrate to a post-treatment process.

2. The method of claim 1 , wherein the pre-treatment process includes at least one of:

an etching process in an integrated dry clean chamber;

an in-situ etching process in reactive gases in a thermal or plasma environment, wherein the reactive gases include halogens, hydrogen halides, or combinations thereof;

depositing a p-type doped or undoped silicon or germanium layer as a sacrificial layer on the exposed silicon-germanium surface;

exposing the substrate to a rapid thermal anneal process; and

exposing the substrate to a wet-clean process.

3. The method of claim 2 , wherein the

germanium source gas is selected from germane (GeH 4 ), germanium dichloride (GeCl 2 ), germanium tetrachloride (GeCl 4 ), dichlorogermane (Cl 2 GeH 2 ), digermane (Ge 2 H 6 ), trigermane (Ge 3 H 8 ), tetragermane (Ge 4 H 10 ), and combinations thereof and

the boron source gas is selected from diborane (B 2 H 6 ), dimethylamine borane, trimethylborane, triethylborane, and combinations thereof.

4. The method of claim 3 , wherein the post-treatment process includes at least one of:

an etching process in an integrated dry clean chamber;

an in-situ etching process in reactive gases in a thermal or plasma environment, wherein the reactive gases include halogens, hydrogen halides, or combinations thereof;

exposing the substrate to a rapid thermal anneal process; and

exposing the substrate to a wet-clean process.

5. The method of claim 4 , wherein the pre-treatment process, the selectively depositing the boron-doped germanium layer, and the post-treatment process are performed without exposing the substrate to atmosphere.

6. The method of claim 1 , wherein the pre-treatment process comprises simultaneously exposing the substrate to NF 3 and Ar plasma by-products.

7. The method of claim 1 , wherein the germanium source gas is selected from digermane (Ge 2 H 6 ), trigermane (Ge 3 H 8 ), tetragermane (Ge 4 H 10 ), and combinations thereof.

8. A method of processing a substrate, comprising:

exposing a substrate having an exposed silicon-germanium surface and an exposed dielectric surface to a pre-treatment process, wherein the pre-treatment process comprises;

simultaneously exposing the substrate to NF 3 and NH 3 plasma by-products;

selectively depositing a boron-doped germanium layer on the exposed silicon-germanium surface, wherein the selectively depositing the boron-doped germanium layer on the exposed silicon-germanium surface comprises:

co-flowing a germanium source gas and a boron source gas;

stopping the flow of the germanium source gas while continuing to flow the boron source gas to deposit an amorphous boron-doped germanium layer on the exposed silicon-germanium surface and the exposed dielectric surface;

annealing the amorphous boron-doped germanium layer to recrystallize the amorphous boron-doped germanium layer formed on the exposed silicon-germanium surface while the amorphous boron-doped germanium layer formed on the exposed dielectric surface remains amorphous; and

etching the amorphous boron-doped germanium layer formed on the exposed dielectric surface; and

exposing the substrate to a post-treatment process.

9. The method of claim 8 , wherein the germanium source gas is selected from germane (GeH 4 ), germanium dichloride (GeCl 2 ), germanium tetrachloride (GeCl 4 ), dichlorogermane (Cl 2 GeH 2 ), digermane (Ge 2 H 6 ), trigermane (Ge 3 H 8 ), tetragermane (Ge 4 H 10 ), and combinations thereof.

10. The method of claim 9 , wherein the boron source gas is selected from diborane (B 2 H 6 ), dimethylamine borane, trimethylborane, triethylborane, and combinations thereof.

11. The method of claim 8 , wherein co-flowing the germanium source gas and the boron source gas comprises:

flowing the germanium source gas at a flow rate from about 0.1 sccm to about 1 sccm; and

flowing the boron source gas at a flow rate from about 1 sccm to about 10 sccm.

12. The method of claim 8 , wherein the germanium source gas is selected from digermane (Ge 2 H 6 ), trigermane (Ge 3 H 8 ), tetragermane (Ge 4 H 10 ), and combinations thereof.

13. A method of processing a substrate, comprising:

exposing a substrate having an exposed silicon-germanium surface and an exposed dielectric surface to a pre-treatment process, wherein the pre-treatment process comprises:

depositing a doped or undoped silicon-germanium sacrificial layer on the exposed silicon germanium surface; and

exposing the sacrificial layer to an etchant to remove the sacrificial layer and expose a clean silicon-germanium surface;

selectively depositing a boron-doped germanium layer on the exposed silicon-germanium surface, wherein the selectively depositing the boron-doped germanium layer on the exposed silicon-germanium surface comprises:

co-flowing a germanium source gas and a boron source gas;

stopping the flow of the germanium source gas while continuing to flow the boron source gas to deposit an amorphous boron-doped germanium layer on the exposed silicon-germanium surface and the exposed dielectric surface;

annealing the amorphous boron-doped germanium layer to recrystallize the amorphous boron-doped germanium layer formed on the exposed silicon-germanium surface while the amorphous boron-doped germanium layer formed on the exposed dielectric surface remains amorphous; and

etching the amorphous boron-doped germanium layer formed on the exposed dielectric surface; and

exposing the substrate to a post-treatment process.

14. The method of claim 13 , wherein co-flowing the germanium source gas and the boron source gas comprises:

flowing the germanium source gas at a flow rate from about 0.1 sccm to about 1 sccm; and

flowing the boron source gas at a flow rate from about 1 sccm to about 10 sccm.

15. The method of any of claim 13 , wherein the pre-treatment process, the selectively depositing the boron-doped germanium layer, and the post-treatment process are performed without exposing the substrate to atmosphere.

16. The method of claim 13 , wherein the germanium source gas is selected from germane (GeH 4 ), germanium dichloride (GeCl 2 ), germanium tetrachloride (GeCl 4 ), dichlorogermane (Cl 2 GeH 2 ), digermane (Ge 2 H 6 ), trigermane (Ge 3 H 8 ), tetragermane (Ge 4 H 10 ), and combinations thereof.

17. The method of claim 16 , wherein the boron source gas is selected from diborane (B 2 H 6 ), dimethylamine borane, trimethylborane, triethylborane, and combinations thereof.

18. The method of claim 13 , wherein the post-treatment process includes at least one of:

an etching process in an integrated dry clean chamber;

an in-situ etching process in reactive gases in a thermal or plasma environment, wherein the reactive gases include halogens, hydrogen halides, or combinations thereof;

exposing the substrate to a rapid thermal anneal process; and

exposing the substrate to a wet-clean process.

19. The method of claim 13 , wherein the germanium source gas is selected from digermane (Ge 2 H 6 ), trigermane (Ge 3 H 8 ), tetragermane (Ge 4 H 10 ), and combinations thereof.