Gopal K Prabhu

US Patent:

8569096, Oct 29, 2013

Filed:

Mar 13, 2013

Appl. No.:

13/798124

Inventors:

Robert Brainard - Sunnyvale CA, US
Arvind Chari - Saratoga CA, US
Alejandro de la Fuente Vornbrock - San Carlos CA, US
Venkatesan Murali - San Jose CA, US
Gopal Prabhu - San Jose CA, US
Venkateswaran Subbaraman - San Jose CA, US
Dong Xu - Fremont CA, US

Assignee:

GTAT Corporation - Nashua NH

International Classification:

H01L 21/00

US Classification:

438 66, 438 72, 257E31124

Abstract:

A free-standing metallic article, and method of making, is disclosed in which the metallic article is electroformed on an electrically conductive mandrel. The mandrel has an outer surface with a preformed pattern, wherein at least a portion of the metallic article is formed in the preformed pattern. The metallic article is separated from the electrically conductive mandrel, which forms a free-standing metallic article that may be coupled with the surface of a semiconductor material for a photovoltaic cell.

US Patent:

8629061, Jan 14, 2014

Filed:

Jun 7, 2012

Appl. No.:

13/490460

Inventors:

Venkatesan Murali - San Jose CA, US
Arvind Chari - Saratoga CA, US
Gopal Prabhu - San Jose CA, US

Assignee:

GTAT Corporation - Nashua NH

International Classification:

H01L 21/768

US Classification:

438667, 257E21585

Abstract:

An interposer is fabricated from a lamina. A donor body is provided, ions are implanted into a first surface of the donor body to define a cleave plane, a temporary carrier is separably contacted to the donor body, and the lamina is cleaved from the donor body. The lamina has front surface and a back surface, with a thickness from the front surface to the back surface. A via hole is formed in the lamina, where the via hole extends through the thickness of the lamina. The temporary carrier is removed from the lamina, and the lamina may be fabricated into an interposer for three-dimensional integrated circuit packages.

US Patent:

20100273329, Oct 28, 2010

Filed:

Sep 10, 2009

Appl. No.:

12/557379

Inventors:

Gopal Prabhu - San Jose CA, US
Kathy J. Jackson - Felton CA, US
Orion Leland - Fremont CA, US
Aditya Agarwal - Sunnyvale CA, US

Assignee:

TWIN CREEKS TECHNOLOGIES, INC. - San Jose CA

International Classification:

H01L 21/304

US Classification:

438691, 257E21237

Abstract:

A donor wafer, for example of silicon, has an irregular surface following cleaving of a lamina from the surface, for example by exfoliation following implant of hydrogen and/or helium ions to define a cleave plane. Pinholes in the lamina leave column asperities at the exfoliated surface of the donor wafer, and the beveled edge may leave an edge asperity which fails to exfoliate. To prepare the surface of the donor wafer for reuse, mechanical grinding removes the column and edge asperities, and minimal additional thickness. Following cleaning, growth and removal of an oxide layer at the surface rounds remaining peaks. The smoothed surface is well adapted to bonding to a receiver element and exfoliation of a new lamina. A variety of devices may be fabricated from the lamina, for example a photovoltaic cell.

US Patent:

20110143480, Jun 16, 2011

Filed:

Dec 11, 2009

Appl. No.:

12/636704

Inventors:

Mohamed M. Hilali - Sunnyvale CA, US
Murali Venkatesan - Santa Clara CA, US
Gopal Prabhu - San Jose CA, US
Zhiyong Li - San Jose CA, US

Assignee:

TWIN CREEKS TECHNOLOGIES, INC. - San Jose CA

International Classification:

H01L 21/322

US Classification:

438 58, 438458, 257E21317

Abstract:

A cleave plane is defined in a semiconductor donor body by implanting ions into the wafer. A lamina is cleaved from the donor body, and a photovoltaic cell is formed which comprises the lamina. The implant may cause some damage to the crystal structure of the lamina. This damage can be repaired by annealing the lamina using microwave energy. If the lamina is bonded to a receiver element, the receiver element may be either transparent to microwaves, or may reflect microwaves, while the semiconductor material absorbs the microwaves. In this way the lamina can be annealed at high temperature while the receiver element remains cooler.

US Patent:

20120192935, Aug 2, 2012

Filed:

Mar 21, 2012

Appl. No.:

13/425870

Inventors:

Steven M. Zuniga - Soquel CA, US
Christopher J. Petti - Mountain View CA, US
Gopal Prabhu - San Jose CA, US

Assignee:

Twin Creeks Technologies, Inc. - San Jose CA

International Classification:

H01L 31/0352
H01L 31/02

US Classification:

136255, 438 68, 257E3111

Abstract:

A method to fabricate a photovoltaic device includes forming first and second contact regions at the first surface of a semiconductor donor body. A cleave plane may be formed by implanting ions into the donor body, and a lamina that includes the contact regions is cleaved from the donor body at the cleave plane. The first surface of the lamina may be contacted with a temporary support and fabricated into a photovoltaic device, wherein the lamina comprises the base of the photovoltaic device.

US Patent:

20130199611, Aug 8, 2013

Filed:

Feb 5, 2012

Appl. No.:

13/366338

Inventors:

Venkatesan Murali - San Jose CA, US
Gopal Prabhu - San Jose CA, US
Orion Leland - Fremont CA, US

Assignee:

Twin Creeks Technologies, Inc. - San Jose CA

International Classification:

H01L 31/0376
H01L 31/18

US Classification:

136258, 438 96, 257E31047

Abstract:

The invention provides for a semiconductor wafer with a metal support element suitable for the formation of a flexible or sag tolerant photovoltaic cell. A method for forming a photovoltaic cell may comprise providing a semiconductor wafer have a thickness greater than 150 μm, the wafer having a first surface and a second surface opposite the first and etching the semiconductor wafer a first time so that the first etching reduces the thickness of the semiconductor wafer to less than 150 μm. After the wafer has been etched a first time, a metal support element may be constructed on or over the first surface; and a photovoltaic cell may be fabricated, wherein the semiconductor wafer comprises the base of the photovoltaic cell.

US Patent:

20130200496, Aug 8, 2013

Filed:

Jul 26, 2012

Appl. No.:

13/558826

Inventors:

Venkatesan Murali - San Jose CA, US
Gopal Prabhu - San Jose CA, US

Assignee:

TWIN CREEKS TECHNOLOGIES, INC. - San Jose CA

International Classification:

H01L 21/30
H01L 29/02
H01L 21/20

US Classification:

257618, 438652, 438482, 257E21295, 257E2109, 257E29002

Abstract:

The invention provides a method of forming an electronic device from a lamina that has a coefficient of thermal expansion that is matched or nearly matched to a constructed metal support. In some embodiments the method comprises implanting the top surface of a donor body with an ion dosage to form a cleave plane followed by exfoliating a lamina from the donor body. After exfoliating the lamina, a flexible metal support that has a coefficient of thermal expansion with a value that is within 10% of the value of the coefficient of thermal expansion of the lamina is constructed on the lamina. In some embodiments the coefficients of thermal expansion of the metal support and the lamina are within 10% or within 5% of each other between the temperatures of 100 and 600 C.

US Patent:

20130200497, Aug 8, 2013

Filed:

Jul 26, 2012

Appl. No.:

13/558836

Inventors:

Venkatesan Murali - San Jose CA, US
Gopal Prabhu - San Jose CA, US
Christopher J. Petti - Mountain View CA, US

Assignee:

TWIN CREEKS TECHNOLOGIES, INC. - San Jose CA

International Classification:

H01L 21/20
H01L 29/06

US Classification:

257618, 438478, 257E29005, 257E2109

Abstract:

The invention provides a method of forming an electronic device from a lamina that has a coefficient of thermal expansion that is matched or nearly matched to a constructed metal support. In some embodiments the method comprises implanting the top surface of a donor body with an ion dosage to form a cleave plane followed by exfoliating a lamina from the donor body. After exfoliating the lamina, a flexible metal support that has a coefficient of thermal expansion with a value that is within 10% of the value of the coefficient of thermal expansion of the lamina is constructed on the lamina. In some embodiments the coefficients of thermal expansion of the metal support and the lamina are within 10% or within 5% of each other between the temperatures of 500 and 1050 C.