Method of manufacturing crystalline silicon solar cells using co diffusion of boron and phosphorus

Abstract

The present invention provides a method of manufacturing a crystalline silicon solar cell, subsequently comprising: providing a crystalline silicon substrate having a first side and a second side opposite the first side; pre-diffusing Phosphorus into a first side of the substrate to render a Phosphorus diffused layer having an initial depth; blocking the first side of the substrate; - exposing a second side of the substrate to a Boron diffusion source; heating the substrate for a certain period of time and to a certain temperature so as to diffuse Boron into the second side of the substrate and to simultaneously diffuse the Phosphorus further into the substrate.

Description

technical field

[0001] The present invention relates to the fabrication of solar cells using crystalline silicon (Si) substrates. One example of such a solar cell is a boron emitter n-base solar cell with a backside region created by phosphorous diffusion. Background technique

[0002] If two diffusion processes (boron and phosphorus) are required, the higher temperature boron diffusion step is usually performed before the lower temperature phosphorus diffusion step, see for example Proceedings of 21st European Photovoltaic Solar Energy Conference by T. Buck et al. (4- 8 September 2006, Dresden, Germany), pp. 1264-1267. This process sequence requires a special protective layer to prevent phosphorus diffusion into the boron diffused face during the phosphorus diffusion step. Boron sometimes diffuses out of the boron diffusion layer to this protective layer and is depleted near the interface. This leads to an increase in the sheet resistance of the emitter and in the series...

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