Layer transfer of films utilizing controlled propagation

• US 20100055874A1
• Filed: 07/24/2009
• Published: 03/04/2010
• Est. Priority Date: 08/28/2008
• Status: Active Grant

• Current Assignee: Silicon Genesis
• Original Assignee: Silicon Genesis
• Inventors: Henley, Francois J.
• Granted Patent: US 8,293,619 B2
• Time in Patent Office: Days
• US Class Current: 438/460
• CPC Class Codes: H01L 21/76254 with separation/delamination along an ion implanted layer, e.g. Smart-cut, Unibond
• CPC Class Codes: H01L 31/18 Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof

Abstract

A film of material may be formed by providing a semiconductor substrate having a surface region and a cleave region located at a predetermined depth beneath the surface region. During a process of cleaving the film from the substrate, shear in the cleave region is carefully controlled to achieve controlled propagation by either KII or energy propagation control. According to certain embodiments, an in-plane shear component (KII) is maintained near zero by adiabatic heating of silicon through exposure to E-beam radiation. According to other embodiments, a surface heating source in combination with an implanted layer serves to guide fracture propagation through the cleave sequence.

Claims

1. A method for cleaving a film of material from a substrate, the method comprising:

providing a substrate having a face and a stressed layer located at a depth below the face;

initiating cleaving within a vicinity of the stressed layer; and

applying external energy to propagate the cleaving using the stressed layer in a controlled manner, wherein propagation above the stressed layer is favored by a KII factor but energetically cannot be supported, such that the stressed layer serves as a barrier to propagation below the depth.

2. The method of claim 1 wherein cleaving is initiated at a location within about 5% of the depth.

3. The method of claim 1 wherein cleaving is initiated at a location within about 10% of the depth.

4. The method of claim 1 further comprising forming the stressed layer by implanting particles.

5. The method of claim 4 wherein the particles comprise hydrogen or helium.

6. The method of claim 1 further comprising forming the stressed layer by deposition.

7. The method of claim 1 wherein the external energy is thermal energy applied in two steps.

8. The method of claim 7 wherein a first step comprises a thermal soak to raise an absolute temperature within the stressed layer, and a second step comprises a thermal pulse to raise a temperature differential between material above the stressed layer and the substrate.

9. The method of claim 8 wherein a timing of the application of the thermal soak and thermal pulse steps is determined based upon a thermal time constant of the film.

10. The method of claim 1 wherein the external energy is thermal energy applied in a single step.

11. The method of claim 10 wherein a timing of the application of the external thermal energy is determined based upon an acoustic time constant of the film.

12. The method of claim 1 wherein the external energy is thermal energy applied at a point deeper than one-half the thickness of the substrate to generate a negative force P and a positive moment M causing separation of the film from the substrate.

13. The method of claim 1 wherein the external energy is thermal energy applied as a beam of electrons, photons, or electromagnetic energy.

14. The method of claim 1 wherein the external energy is mechanical energy applied as moment M and force P imparted on the film.

15. The method of claim 14 wherein the mechanical energy is applied energy applied using ultrasonic excitation of the film.

16. The method of claim 14 wherein the mechanical energy is applied by pushing utilizing a wedge or a wire inserted between the film and the substrate.

17. The method of claim 14 wherein the mechanical energy is applied by pulling utilizing vacuum suction or electrostatic attraction on the face from above.

18. The method of claim 1 wherein the external energy is a combination of thermal and mechanical energy imparted on the film and substrate area near the crack tip.

19. A method for cleaving a film of material from a substrate, the method comprising:

providing a substrate having a face;

initiating cleaving at a depth in the substrate to release an overlying film; and

applying external thermal energy to propagate the cleaving in a controlled manner such that a KII factor is maintained at or about zero along the depth.

20. The method of claim 19 wherein the thermal energy is applied to the face to adiabatically heat the film and generate a positive force (P) and a positive moment (M) resulting in separation of the film.

21. The method of claim 19 wherein the thermal energy is applied as a beam of electrons, photons, or electromagnetic energy.

22. The method of claim 19 wherein the thermal energy is applied as a thermal sink to a portion of the substrate other than the film to generate a positive force (P) and a positive moment (M) resulting in separation of the film.

23. The method of claim 19 further comprising forming a stressed layer at the depth by implanting particles into the face.

24. The method of claim 23 wherein the particles comprise hydrogen or helium.

25. The method of claim 19 wherein additional external energy is applied as mechanical energy as a moment M and a force P imparted on the film.

26. The method of claim 25 wherein the applied mechanical energy is applied using ultrasonic excitation of the film.

27. The method of claim 25 wherein the mechanical energy is applied by inserting a wedge or wire between the film and the substrate.

28. The method of claim 25 wherein the mechanical energy is applied by pulling on the film from above utilizing vacuum suction or electrostatic attraction.

29. A method for cleaving a film of material from a substrate, the method comprising:

providing a substrate having a face and a stressed layer located at a depth below the face;

initiating cleaving within a vicinity of the stressed layer;

applying external thermal energy in two steps to propagate the cleaving using the stressed layer in a controlled manner,

wherein a first step comprises a thermal soak to raise an absolute temperature within the stressed layer, and a second step comprises a thermal pulse to raise a temperature differential between material above the stressed layer and the substrate, and

wherein propagation above the stressed layer is favored by a KII factor but energetically cannot be supported, such that the stressed layer serves as a barrier to propagation below the depth.

30. The method of claim 29 wherein cleaving is initiated at a location within about 5% of the depth.

31. The method of claim 29 wherein cleaving is initiated at a location within about 10% of the depth.

32. The method of claim 29 further comprising forming the stressed layer by implanting particles.

33. The method of claim 32 wherein the particles comprise hydrogen or helium.

34. The method of claim 29 wherein a timing of the application of the thermal soak and thermal pulse steps is determined based upon a thermal time constant of the film.