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Silicon cells made by self-aligned selective-emitter plasma-etchback process

United States Patent

6,091,021
July 18, 2000
View the Complete Patent at the US Patent & Trademark Office
Sandia National Laboratories - Visit the Intellectual Property Management and Licensing Website
Photovoltaic cells and methods for making them are disclosed wherein the metallized grids of the cells are used to mask portions of cell emitter regions to allow selective etching of phosphorus-doped emitter regions. The preferred etchant is SF.sub.6 or a combination of SF.sub.6 and O.sub.2. This self-aligned selective etching allows for enhanced blue response (versus cells with uniform heavy doping of the emitter) while preserving heavier doping in the region beneath the gridlines needed for low contact resistance. Embodiments are disclosed for making cells with or without textured surfaces. Optional steps include plasma hydrogenation and PECVD nitride deposition, each of which are suited to customized applications for requirements of given cells to be manufactured. The techniques disclosed could replace expensive and difficult alignment methodologies used to obtain selectively etched emitters, and they may be easily integrated with existing plasma processing methods and techniques of the invention may be accomplished in a single plasma-processing chamber.
Ruby; Douglas S. (Albuquerque, NM), Schubert; William K. (Albuquerque, NM), Gee; James M. (Albuquerque, NM), Zaidi; Saleem H. (Albuquerque, NM)
Sandia Corporation (Albuquerque, NM)
09/ 191,319
November 13, 1998
GOVERNMENT RIGHTS The United States Government has rights in this invention pursuant to Contract No. DE-AC04-94AL85000 awarded by the U.S. Department of Energy. The Government has certain rights in this invention