Sunpower Corporation

Pongsthorn Uralwong

Douglas H Rose

David D Smith

Thomas Pass

Neil Kaminar

Thomas Phu

Luca Pavani

A solar cell is fabricated by etching one or more of its layers without substantially etching another layer of the solar cell. In one embodiment, a copper layer in the solar cell is etched without substantially etching a topmost metallic layer comprising tin. For example, an etchant comprising sulfuric acid and hydrogen peroxide may be employed to etch the copper layer selective to the tin layer. A particular example of the aforementioned etchant is a Co-Bra Etch&#xae; etchant modified to comprise about 1% by volume of sulfuric acid, about 4% by volume of phosphoric acid, and about 2% by volume of stabilized hydrogen peroxide. In one embodiment, an aluminum layer in the solar cell is etched without substantially etching the tin layer. For example, an etchant comprising potassium hydroxide may be employed to etch the aluminum layer without substantially etching the tin layer.

Etching of solar cell materials

A solar cell is fabricated by etching one or more of its layers without substantially etching another layer of the solar cell. In one embodiment, a copper layer in the solar cell is etched without substantially etching a topmost metallic layer comprising tin. For example, an etchant comprising sulfuric acid and hydrogen peroxide may be employed to etch the copper layer selective to the tin layer. A particular example of the aforementioned etchant is a Co-Bra Etcho&#xae; etchant modified to comprise about 1% by volume of sulfuric acid, about 4% by volume of phosphoric acid, and about 2% by volume of stabilized hydrogen peroxide. In one embodiment, an aluminum layer in the solar cell is etched without substantially etching the tin layer. For example, an etchant comprising potassium hydroxide may be employed to etch the aluminum layer without substantially etching the tin layer.

A carrier for use in processing of a plurality of wafers or other substrates includes a support frame on which the wafers are mounted and in one embodiment at least one auxiliary frame for holding the substrates on the support frame. A plurality of clips extend from the auxiliary frame and engage the substrates in pressure engagement, and fasteners retain the auxiliary frame in position with respect to the support frame. In one embodiment two auxiliary frames can be employed for holding wafers on opposing surfaces of the support frame. The support frame has electrically non-conducting surfaces whereby the processing does not affect the support frame, and the auxiliary frame is made of electrically non-conductive material. The clips are electrically conductive and bridge current from the support frame to the wafers during plating operations. In another embodiment, auxiliary frame are not used and the wafer retention clips are mounted on the support frame. In use, the carrier can support a high number of units for processing with no significant mechanical stress being transferred to the wafers during loading and unloading from the carrier. The carriers and wafers can be transferred easily for different chemical baths and can be handled safely during rinsing and drying steps.

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Campbell, CA, United States of America

Pongsthorn Uralwong