Back side contact solar cell structures and fabrication processes

US7820475B2 · kind B2 · utility

Assignee

• SUNPOWER CORPORATION · US

Inventors

• Denis De Ceuster · Woodside, US
• Peter John Cousins · Menlo Park, US
• Richard M. Swanson · Los Altos, US
• Jane Manning · Woodside, US

Key dates

• Filing date: Dec 20, 2006
• Grant date: Oct 26, 2010
• Expiry date: Apr 24, 2029

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02P70/50

Abstract

In one embodiment, active diffusion junctions of a solar cell are formed by diffusing dopants from dopant sources selectively deposited on the back side of a wafer. The dopant sources may be selectively deposited using a printing method, for example. Multiple dopant sources may be employed to form active diffusion regions of varying doping levels. For example, three or four active diffusion regions may be fabricated to optimize the silicon/dielectric, silicon/metal, or both interfaces of a solar cell. The front side of the wafer may be textured prior to forming the dopant sources using a texturing process that minimizes removal of wafer material. Openings to allow metal gridlines to be connected to the active diffusion junctions may be formed using a self-aligned contact opening etch process to minimize the effects of misalignments.