METHOD AND STRUCTURE FOR THICK LAYER TRANSFER USING A LINEAR ACCELERATOR

• US 20080206962A1
• Filed: 11/05/2007
• Published: 08/28/2008
• Est. Priority Date: 11/06/2006
• Status: Active Grant

• Current Assignee: Silicon Genesis
• Original Assignee: Silicon Genesis
• Inventors: Henley, Francois J., Adibi, Babak, Lamm, Albert
• Granted Patent: US 8,124,499 B2
• Time in Patent Office: Days
• US Class Current: 438/460
• CPC Class Codes: H01L 21/26506 in group IV semiconductors
• CPC Class Codes: H01L 21/2658 of a molecular ion, e.g. decaborane
• CPC Class Codes: H01L 21/26593 at a temperature lower than room temperature
• CPC Class Codes: H01L 21/3221 of silicon bodies, e.g. for gettering
• CPC Class Codes: H01L 21/76254 with separation/delamination along an ion implanted layer, e.g. Smart-cut, Unibond
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

A method for fabricating free standing thickness of materials using one or more semiconductor substrates, e.g., single crystal silicon, polysilicon, silicon germanium, germanium, group III/IV materials, and others. In a specific embodiment, the present method includes providing a semiconductor substrate having a surface region and a thickness. The method includes subjecting the surface region of the semiconductor substrate to a first plurality of high energy particles generated using a linear accelerator to form a region of a plurality of gettering sites within a cleave region, the cleave region being provided beneath the surface region to defined a thickness of material to be detached, the semiconductor substrate being maintained at a first temperature. In a specific embodiment, the method includes subjecting the surface region of the semiconductor substrate to a second plurality of high energy particles generated using the linear accelerator, the second plurality of high energy particles being provided to increase a stress level of the cleave region from a first stress level to a second stress level. In a preferred embodiment, the semiconductor substrate is maintained at a second temperature, which is higher than the first temperature. The method frees the thickness of detachable material using a cleaving process, e.g., controlled cleaving process.

Claims

1. A method for fabricating a free standing thickness of materials using one or more semiconductor substrates, comprising:

providing a semiconductor substrate having a surface region and a thickness;

subjecting the surface region of the semiconductor substrate to a first plurality of high energy particles generated using a linear accelerator to form a region of a plurality of gettering sites within a cleave region, the cleave region being provided beneath the surface region to defined a thickness of material to be detached, the semiconductor substrate being maintained at a first temperature;

subjecting the semiconductor substrate to a treatment process;

subjecting the surface region of the semiconductor substrate to a second plurality of high energy particles generated using the linear accelerator, the second plurality of high energy particles being provided to increase a stress level of the cleave region from a first stress level to a second stress level, the semiconductor substrate being maintained at a second temperature; and

freeing the thickness of detachable material using a cleaving process.

2. The method of claim 1 wherein the thickness of detachable material is free standing.

3. The method of claim 1 wherein the semiconductor substrate comprises monocrystalline silicon or polycrystalline silicon.

4. The method of claim 1 wherein the first high velocity particles or the second high velocity particles comprise hydrogen species or helium species.

5. The method of claim 3 wherein the hydrogen species are provided at a dose of 2×

10¹⁶ per cm² and less.

6. The method of claim 1 wherein the linear accelerator comprises a radio frequency quadrupole (RFQ).

7. The method of claim 1 wherein the first plurality of high velocity particles are provided in an energy ranging from 0.5 MeV to 12 MeV.

8. The method of claim 1 wherein the treatment process is a thermal process provided at a temperature of 400 Degree Celsius or higher to render the microscopic defect region to be close to the cleave region and stabilize the microscopic defect region.

9. The method of claim 1 wherein the first temperature is less than about 250 Degree Celsius, and the second temperature is greater than about 250 Degree Celsius and no greater than 550 Degrees Celsius.

10. The method of claim 1 wherein the thickness of detachable material has a thickness of between about 50-100 um.

11. The method of claim 1 wherein the first plurality of high energy particles and the second plurality of high energy particles are provided from the linear accelerator in an expanded beam having a dimension of about 500 mm in diameter on the surface region of the semiconductor substrate.

12. A method for forming a free standing thickness of layer transferred material, the method comprising:

providing a crystalline substrate material having a surface region;

introducing a plurality of first particles at a first dose range and within a first temperature range, whereupon the first dose range being less than an amount sufficient to cause the plurality of particles to be permanently disposed in the crystalline substrate material at an accumulation region, through the surface region to the accumulation region of the crystalline substrate material to form an implant profile having a peak concentration and a base spatially disposed within a dimension to form the accumulation region, the first particles causing a plurality of defects in the crystalline material in the accumulation region, the accumulation region being defined by a depth greater than about 20 microns beneath the surface region and a slice of crystalline material to be detached between the accumulation region and the surface region;

performing a treatment process on the crystalline substrate material to cause formation of a plurality of substantially permanent defects that have been quenched in the crystalline substrate material from the first particles in the accumulation region; and

introducing a plurality of second particles at a second dose range and a second temperature range into the accumulation region to increase an internal stress in the accumulation region to cause a portion of the accumulation region to be cleavable; and

forming a free standing thickness of crystalline material by detaching the thickness of crystalline material from a remaining portion of the crystalline substrate material.

13. The method of claim 12 wherein the crystalline substrate material is a single crystal silicon or polycrystalline silicon.

14. The method of claim 12 wherein the first dose range is from about 2×

10¹⁵ to 2×

10¹⁶ cm<sup>−

1</sup>.

15. The method of claim 12 wherein the plurality of first particles are introduced while the crystalline substrate material is maintained at a temperature ranging from about −

50 to +250 Degrees Celsius.

16. The method of claim 12 wherein the first plurality of particles comprises of hydrogen.

17. The method of claim 12 wherein the base has a width of about 2 Rp and less.

18. A method for slicing a plurality of films from a bulk material, the method comprising:

providing a bulk material having a surface region and a weight;

repeatedly cleaving a plurality of films from the bulk material, each of the plurality of films having a thickness of greater than about 20 microns to less than about 150 microns; and

using more than about 70% of the weight of the bulk material for the plurality of films.

19. The method of claim 18 wherein the bulk material is provided as an ingot of single crystal silicon or as a tile of polycrystalline silicon.

20. The method of claim 18 wherein the first plurality of particles or the second plurality of particles comprise hydrogen species or helium species.

21. The method of claim 18 further comprising returning an unused portion of the bulk material to create a second amount of the material in bulk form.

22. A method for efficiently separating films from a bulk material, the method comprising:

providing a bulk material having a surface region; and

repeatedly cleaving a plurality of films from the bulk material, each of the films having a thickness of about 20 microns or greater, such that an efficiency of 80% or greater is achieved, wherein, efficiency=(total wt. of free standing layers)/(wt. of bulk material consumed)×

100.

23. The method of claim 22 wherein the bulk material is provided as an ingot of single crystal silicon or as a tile of polycrystalline silicon.

24. The method of claim 22 wherein the first plurality of particles and the second plurality of particles are implanted at energies between about 0.5-20 MeV.

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

providing a bulk semiconductor material having a surface;

implanting through the surface and into the bulk material, a first plurality of particles output by a linear accelerator at an energy of between about 0.5-12 MeV, to form a cleave region comprising a plurality of gettering sites, a distance between the cleave region and the surface defining a thickness of a semiconductor material to be detached; and

freeing the thickness of detachable material using a controlled cleaving process.

26. The method of claim 25 wherein:

the implanting is performed in a pattern to create the cleave region locally; and

the controlled cleaving process is initiated at the local cleave region and then propagated across the bulk material.

27. The method of claim 26 wherein the implanting is performed by controlling a dwell time of a beam of the first plurality of particles.

28. The method of claim 26 wherein the implanting is performed by controlling a number of exposures of the cleave region to a beam of the first plurality of particles.

29. The method of claim 26 wherein the controlled cleaving action is initiated by the application of physical stress to the substrate.

30. The method of claim 29 wherein the physical stress is applied to the substrate by changing a thermal state of the substrate, by striking the substrate, or by changing a shape of an element to which the substrate is bound.