METHOD FOR GROWING GERMANIUM EPITAXIAL FILMS

• US 20110036289A1
• Filed: 08/11/2009
• Published: 02/17/2011
• Est. Priority Date: 08/11/2009
• Status: Active Grant

• Current Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: Carothers, Daniel N., Hill, Craig M., Pomerene, Andrew T.S., Vu, Vu A.
• Granted Patent: US 9,305,779 B2
• Time in Patent Office: Days
• US Class Current: 117/94
• CPC Class Codes: H01L 21/02381 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/0245 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02502 consisting of two layers
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02579 P-type
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02645 Seed materials
• CPC Class Codes: H01L 21/02658 Pretreatments cleaning in general H01L21/02041

Abstract

A method for growing germanium epitaxial films is disclosed. Initially, a silicon substrate is preconditioned with hydrogen gas. The temperature of the preconditioned silicon substrate is then decreased, and germane gas is flowed over the preconditioned silicon substrate to form an intrinsic germanium seed layer. Next, a mixture of germane and phosphine gases can be flowed over the intrinsic germanium seed layer to produce an n-doped germanium seed layer. Otherwise, a mixture of diborane and germane gases can be flowed over the intrinsic germanium seed layer to produce a p-doped germanium seed layer. At this point, a bulk germanium layer can be grown on top of the doped germanium seed layer.

Claims

1. A method for growing germanium epitaxial films, said method comprising:

preconditioning a silicon substrate with hydrogen gas at a first temperature;

decreasing said first temperature of said preconditioned silicon substrate to a second temperature;

flowing germane gas over said preconditioned silicon substrate to form an intrinsic germanium seed layer;

increasing said second temperature of said preconditioned silicon substrate to a third temperature;

flowing a mixture of phosphine and germane gases over said intrinsic germanium seed layer to produce an n-doped germanium seed layer; and

growing a bulk germanium film layer on top of said n-doped germanium layer.

2. The method of claim 1, wherein said preconditioning further includes preconditioning said silicon substrate with hydrogen gas at approximately 3E⁻

4 mBar for approximately 60 minutes at approximately 750°

C.

3. The method of claim 1, wherein said decreasing further includes decreasing said first temperature from approximately 750°

C. to approximately 350°

C. at approximately 2°

C. per minute.

4. The method of claim 1, wherein said flowing germane gas further includes flowing germane gas over said preconditioned silicon substrate at approximately 1.5E⁻

3 mBar for approximately 120 minutes.

5. The method of claim 1, wherein said increasing further includes increasing said second temperature of said preconditioned silicon substrate from approximately 350°

C. to approximately 600°

C. at approximately 2°

C. per minute.

6. The method of claim 1, wherein said mixture of phosphine and germane gases includes an approximately 1:

3 mixture of phosphine and germane gases.

7. The method of claim 1, wherein said mixture of phosphine and germane gases is flowed over said germanium seed layer at approximately 6E⁻

4 mBar for approximately 30 minutes.

8. The method of claim 1, wherein said bulk germanium film layer is intrinsic germanium film.

9. The method of claim 1, wherein said bulk germanium film layer is doped germanium film.

10. The method of claim 1, wherein said growing further includes flowing germane gas over said preconditioned germanium layer at approximately 1.5E⁻

3 mBar for approximately 480 minutes.

11. A method for growing germanium epitaxial films, said method comprising:

preconditioning a silicon substrate with hydrogen gas at a first temperature;

decreasing said first temperature of said preconditioned silicon substrate to a second temperature;

flowing germane gas over said preconditioned silicon substrate to form an intrinsic germanium seed layer;

increasing said second temperature of said preconditioned silicon substrate to a third temperature;

flowing a mixture of diborane and germane gases over said intrinsic germanium seed layer to produce an p-doped germanium layer; and

growing a bulk germanium film layer on top of said p-doped germanium layer.

12. The method of claim 11, wherein said preconditioning further includes preconditioning said silicon substrate with hydrogen gas at approximately 3E⁻

4 mBar for approximately 60 minutes at approximately 750°

C.

13. The method of claim 11, wherein said decreasing further includes decreasing said first temperature from approximately 750°

C. to approximately 350°

C. at approximately 2°

C. per minute.

14. The method of claim 11, wherein said flowing germane gas further includes flowing germane gas over said preconditioned silicon substrate at approximately 1.5E⁻

3 mBar for approximately 120 minutes.

15. The method of claim 11, wherein said increasing further includes increasing said second temperature of said preconditioned silicon substrate from approximately 350°

C. to approximately 600°

C. at approximately 2°

C. per minute.

16. The method of claim 11, wherein said mixture diborane and germane gases includes an approximately 1:

1 mixture of diborane and germane gases.

17. The method of claim 11, wherein said mixture of diborane and germane gases is flowed over said germanium seed layer at approximately 6E⁻

4 mBar for approximately 30 minutes.

18. The method of claim 11, wherein said bulk germanium film layer is intrinsic germanium film.

19. The method of claim 11, wherein said bulk germanium film layer is doped germanium film.

20. The method of claim 11, wherein said growing further includes flowing germane gas over said preconditioned germanium layer at approximately 1.5E⁻

3 mBar for approximately 480 minutes.