Etching of solar cell materials

US7455787B2 · kind B2 · utility

Assignee

• SUNPOWER CORPORATION · US

Inventors

• Douglas Rose · Austin, US
• Pongsthorn Uralwong · Campbell, US
• David D. Smith · Dublin, US

Key dates

• Filing date: Aug 1, 2003
• Grant date: Nov 25, 2008
• Expiry date: Feb 15, 2026

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02E10/50

Abstract

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® 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.