Method and structure for fabricating solar cells using a layer transfer process

• US 7,759,220 B2
• Filed: 04/05/2007
• Issued: 07/20/2010
• Est. Priority Date: 04/05/2006
• Status: Active Grant

• Current Assignee: Silicon Genesis
• Original Assignee: Silicon Genesis
• Inventors: Henley, Francois J
• Primary Examiner(s): Stark, Jarrett J
• Application Number:
  US11/784,524
• Publication Number:
  US 20080160661A1
• Time in Patent Office: 1,202 Days
• Field of Search: 438/458, 438/455, 257/E21.48, 257/E21.568
• US Class Current: 438/458
• 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 reusable silicon substrate device for use with layer transfer process. The device has a reusable substrate having a surface region, a cleave region, and a total thickness of material. The total thickness of material is at least N times greater than a first thickness of material to be removed. In a specific embodiment, the first thickness of material to be removed is between the surface region and the cleave region, whereupon N is an integer greater than about ten. The device also has a chuck member adapted to hold a handle substrate member in place. The chuck member is configured to hold the handle substrate in a manner to facilitate bonding the handle substrate to the first thickness of material to be removed. In a preferred embodiment, the device has a mechanical pressure device operably coupled to the chuck member. The mechanical pressure device is adapted to provide a force to cause bonding of the handle substrate to the first thickness of material to be removed.

Claims

1. A method for fabricating a photovoltaic cell, the method comprising:

providing a reusable substrate having a surface region, a cleave region, and a total thickness of material, the total thickness of material being at least N times greater than a first thickness of material to be removed, the first thickness of material to be removed being between the surface region and the cleave region;

coupling the surface region of the reusable substrate to a first surface region of an optically transparent substrate, the optically transparent substrate comprising the first surface region and a second surface region;

contacting a first electrode to a first region of the reusable substrate, and contacting a second electrode to a second region of the reusable substrate; and

providing a first voltage through the first electrode at the first region and a second voltage through the second electrode at the second region of the reusable substrate to create a voltage differential across the first and second regions to cause an increase in energy at one or more portions of the cleave region to facilitate removal of the first thickness of material from the reusable substrate, while the surface region remains coupled to the first surface region, to form a cleaved surface region coupled to the first surface region of the optically transparent substrate.

2. The method of claim 1 further comprising subjecting the cleaved surface region using at least a mechanical polishing or a chemical etching process to remove a portion of a hydrogen damaged layer from the cleaved surface region.

3. The method of claim 1 further comprising plasma activating the surface region and the first surface region before coupling the surface region to the first surface region.

4. The method of claim 1 wherein the coupling comprises an optical coupling material between the surface region and the first surface region.

5. The method of claim 4 wherein the optical coupling material comprises a tin oxide, indium tin oxide, zinc oxide, or titanium dioxide.

6. The method of claim 1 further comprising forming a second thickness of semiconductor material using at least a solid phase epitaxy process or a gaseous phase epitaxial process to form substantially single crystal silicon material.

7. The method of claim 1 further comprising forming a second thickness of semiconductor material using at least forming an amorphous silicon layer.

8. The method of claim 7 further comprising crystallizing the amorphous silicon layer.

9. The method of claim 1 wherein the first thickness of semiconductor material comprises a single crystal silicon material.

10. The method of claim 1 wherein the optically transparent material comprises a glass substrate or a quartz substrate or a plastic substrate.

11. The method of claim 1 wherein the optically transparent material comprises a conductive material including indium tin oxide or tin oxide.

12. The method of claim 1 wherein the thickness of material comprises one or more photovoltaic regions, the one or more photovoltaic regions comprising a first electrode and a second electrode.

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

14. The method of claim 1 wherein the cleaving comprises an initiation process and a propagation process to free the first thickness of material from a remaining portion of the semiconductor substrate.

15. The method of claim 1 wherein the voltage differential ranges from about 0.1 Volts to about 100 Volts.

16. The method of claim 1 wherein the voltage differential is provided between a first electrode and a second electrode, the first electrode being coupled to the first region and the second electrode being coupled to the second region.

17. A method fabricating one or more semiconductor substrates, the method comprising:

providing a reusable substrate having a surface region, a cleave region, and a total thickness of material, the total thickness of material being at least N times greater than a first thickness of material to be removed, the first thickness of material to be removed being between the surface region and the cleave region;

contacting a first electrode to a first region of the reusable substrate, and contacting a second electrode to a second region of the reusable substrate; and

providing a first voltage through the first electrode at the first region and a second voltage through the second electrode at the second region of the reusable substrate to create a voltage differential across the first and second regions to cause an increase in energy at one or more portions of the surface region to facilitate bonding of the surface region to a first surface region of a handle substrate.

18. The method of claim 17 wherein the increase in energy causes an increase in temperature of the surface region from a first temperature to a second temperature.

19. The method of claim 17 wherein the increase in energy causes an increase in temperature from a first temperature to a second temperature, the second temperature being greater than about 200 Degrees Celsius.

20. A method of fabricating one or more semiconductor substrates, the method comprising:

providing a reusable substrate having a surface region, a cleave region, and a total thickness of material, the total thickness of material being at least N times greater than a first thickness of material to be removed, the first thickness of material to be removed being between the surface region and the cleave region; and

providing a first voltage at a first region and a second voltage at a second region of the reusable substrate to create a voltage differential across the first and second regions to cause an increase in energy at one or more portions of the cleave region to change a characteristic of the cleave region from a first characteristic to a second characteristic, the second characteristic causing removal of the first thickness of material from the reusable substrate.

21. The method of claim 20 wherein the voltage differential increases a temperature of one or more portions of the surface region to cure a bonding layer provided overlying the one or more portions of the surface region.

22. A method fabricating one or more semiconductor substrates, the method comprising:

providing a reusable substrate having a surface region, a cleave region, and a total thickness of material, the total thickness of material being at least N times greater than a first thickness of material to be removed, the first thickness of material to be removed being between the surface region and the cleave region;

contacting a first electrode to a first region of the reusable substrate, and contacting a second electrode to a second region of the reusable substrate; and

providing a first voltage through the first electrode at the first portion of the reusable substrate and a second voltage through the second electrode at the second portion of the reusable substrate, thereby subjecting a voltage differential between a first region and a second region of the reusable substrate to cause an increase in energy at one or more portions of the surface region.

23. The method of claim 22 wherein the increase in energy facilitates bonding of the surface region to a first surface region of a handle substrate.

24. The method of claim 22 wherein the increase in energy causes an increase in temperature of the surface region from a first temperature to a second temperature.

25. The method of claim 22 wherein the increase in energy causes an increase in temperature from a first temperature to a second temperature, the second temperature being greater than about 200 Degrees Celsius.