Method and system for fabricating strained layers for the manufacture of integrated circuits

• US 7,094,666 B2
• Filed: 01/24/2005
• Issued: 08/22/2006
• Est. Priority Date: 07/29/2004
• Status: Expired due to Fees

• Current Assignee: Silicon Genesis
• Original Assignee: Silicon Genesis
• Inventors: Henley, Francois J., Ong, Philip James, Malik, Igor J., Kirk, Harry R.
• Primary Examiner(s): Pham, Hoai
• Assistant Examiner(s): DUONG, KHANH B
• Application Number:
  US11/043,477
• Publication Number:
  US 20060024917A1
• Time in Patent Office: 575 Days
• Field of Search: 438/455, 438/457, 438/458, 438/464
• US Class Current: 438/457
• CPC Class Codes: H01L 21/2007 Bonding of semiconductor wafers to insulating substrates or to semiconducting substrates using an intermediate insulating layer H01L21/2011 takes precedence; bonding of semiconductor wafers to semiconductor wafers for junction formation H01L21/187
• CPC Class Codes: H01L 21/302 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting

Abstract

A method for forming a strained layer of semiconductor material, e.g., silicon, germanium, Group III/V, silicon germanium alloy. The method includes providing a non-deformable surface region having a first predetermined radius of curvature, which is defined by R(1) and is defined normal to the surface region. The method includes providing a first substrate (e.g., silicon wafer) having a first thickness. Preferably, the first substrate has a face, a backside, and a cleave plane defined within the first thickness. The method includes a step of overlying the backside of the first substrate on a portion of the surface region having the predetermined radius of curvature to cause a first bend within the thickness of material to form a first strain within a portion of the first thickness. The method provides a second substrate having a second thickness, which has a face and a backside. The method includes a step of overlying the face of the second substrate on a portion of the face of the first substrate to cause a second bend within the thickness of material to form a second strain within a portion of the second thickness. A step of joining the face of the second substrate to the face of the first substrate form a sandwich structure while maintaining the first bend in the first substrate and the second bend in the second substrate. Preferably, joining occurs using a low temperature process such as plasma activated bonding or the like.

Claims

1. A method for forming a strained layer of semiconductor material, the method comprising:

providing a non-deformable surface region having a first predetermined radius of curvature, the first predetermined radius of curvature being defined by R(1) and being defined normal to the surface region;

providing a first substrate having a first thickness, the first substrate having a face, a backside, and a cleave plane within the first thickness;

overlying the backside of the first substrate on a portion of the surface region having the predetermined radius of curvature to cause a first bend within the thickness of material to form a first strain within a portion of the first thickness;

providing a second substrate having a second thickness, the second substrate having a face and a backside;

overlying the face of the second substrate on a portion of the face of the first substrate to cause a second bend within the thickness of material to form a second strain within a portion of the second thickness;

joining the face of the second substrate to the face of the first substrate to form a sandwich structure while maintaining the first bend in the first substrate and the second bend in the second substrate; and

releasing a portion of a thickness the first substrate along a vicinity of the cleave plane to free the portion of the thickness of material from a remaining portion of the first substrate while being attached to the second substrate; and

conforming the shape of the thickness of material to the second substrate as a radius of curvature on the second substrate approaches a second predetermined radius (R2) of curvature; and

increasing a magnitude of a strain from the first strain to a third strain within the thickness of material as the thickness of material of conforms in shape to the second substrate as the radius of curvature on the second substrate approaches the second predetermined radius of curvature.

2. The method of claim 1 wherein the joining is provided by plasma activated bonding.

3. The method of claim 2 wherein the plasma activated bonding is maintained at less than 1000 degrees Celsius.

4. The method of claim 1 wherein, the first radius of curvature is defined by an imaginary circle, the imaginary circle being continuous or variable.

5. The method of claim 1 wherein the second radius of curvature is defined by infinity.

6. The method of claim 1 wherein the releasing comprises a controlled cleaving process.

7. The method of claim 1 wherein the releasing comprises a thermal cleaving process.

8. The method of claim 1 wherein the joining is a rolling process that physically mates the face of the second substrate to the face of the first substrate using a rolling action defined by an axis formed between a separated region between the face of the second substrate and the face of the first substrate and a connected region between the face of the second substrate and the face of the first substrate.

9. The method of claim 1 wherein the first substrate is overlying the surface region and maintained using a mechanical clamp.

10. The method of claim 1 wherein the second substrate is overlying the first substrate and maintained using a mechanical clamp.

11. The method of claim 1 wherein the first substrate is overlying the surface region by a vacuum or an electrostatic force.

12. The method of claim 1 wherein the joining is a bonding process using a silicon bearing material.

13. The method of claim 1 wherein the first substrate comprises a first silicon wafer and the second substrate comprises a second silicon wafer.

14. The method of claim 1 further comprising subjecting the sandwich structure to a heat treatment process.

15. The method of claim 14 wherein heat treatment process maintains substantially no stress at an interface between the first substrate and the second substrate.

16. The method of claim 1 wherein the strain in the released thickness of material is characterized by a tensile mode.

17. A method for forming a strained layer of semiconductor material, the method comprising:

providing a non-deformable surface region having a first predetermined radius of curvature, the first predetermined radius of curvature being defined by R(1) and being defined normal to the surface region;

providing a first substrate having a first thickness, the first substrate having a face and a backside;

overlying the backside of the first substrate on a portion of the surface region having the predetermined radius of curvature to cause a first bend within the thickness of material to form a first strain within a portion of the first thickness;

providing a second substrate having a second thickness, the second substrate having a face, a backside, and a cleave plane within the second thickness;

overlying the face of the second substrate on a portion of the face of the first substrate to cause a second bend within the thickness of material to form a second strain within a portion of the second thickness;

joining the face of the second substrate to the face of the first substrate to form a sandwich structure while maintaining the first bend in the first substrate and the second bend in the second substrate; and

releasing a portion of a thickness the second substrate along a vicinity of the cleave plane to free the portion of the thickness of material from a remaining portion of the second substrate while being attached to the first substrate; and

conforming the shape of the thickness of material to the first substrate as a radius of curvature on the first substrate approaches a second predetermined radius (R2) of curvature; and

increasing a magnitude of a strain from the first strain to a third strain within the thickness of material as the thickness of conforms in shape to the first substrate as the radius of curvature on the first substrate approaches the second predetermined radius of curvature.

18. The method of claim 17 wherein the joining is provided by plasma activated bonding.

19. The method of claim 18 wherein the plasma activated bonding is maintained at less than 1000 degrees Celsius.

20. The method of claim 17 wherein the first radius of curvature is defined by an imaginary circle, the imaginary circle being continuous or variable.

21. The method of claim 17 wherein the second radius of curvature is defined by infinity.

22. The method of claim 17 wherein the releasing comprises a controlled cleaving process along a vicinity of the cleave plane.

23. The method of claim 17 wherein the releasing comprises a thermal cleaving process along a vicinity of the cleave plane.

24. The method of claim 17 wherein the joining is a rolling process that physically mates the face of the second substrate to the face of the first substrate using a rolling action defined by an axis formed between a separated region between the face of the second substrate and the face of the first substrate and a connected region between the face of the second substrate and the face of the first substrate.

25. The method of claim 17 wherein the first substrate is overlying the surface region and maintained using a mechanical clamp.

26. The method of claim 17 wherein the second substrate is overlying the first substrate and maintained using a mechanical clamp.

27. The method of claim 17 wherein the first substrate is overlying the surface region by a vacuum or an electrostatic force.

28. The method of claim 17 wherein the joining is a bonding process using a silicon bearing material.

29. The method of claim 17 wherein the first substrate comprises a first silicon wafer and the second substrate comprises a second silicon wafer.

30. The method of claim 17 further comprising subjecting the sandwich structure to a heat treatment process.

31. The method of claim 30 wherein heat treatment process maintains substantially no stress at an interface between the first substrate and the second substrate.

32. The method of claim 17 wherein the strain is characterized by a compressive mode in the released thickness of material.