Patent ID: 8039289
Filing Date: 2011-10-18
Classification: F27B,F27D,H01L,Y10S

Abstract:
1. A method of continuous diffusion layer firing of Photo-Voltaic (PV) solar cell wafers that have had a doping layer containing a dopant applied to at least one surface of said wafer substrate selected from a first top surface and a second bottom surface, comprising the steps of: a) transporting a plurality of wafers sequentially through a plurality of heating and cooling zones from a furnace inlet to a furnace outlet, said zones being disposed in abutting relationship to define there-through a continuous longitudinal processing conveyor path oriented in a generally horizontal plane and said wafers being oriented with said first surface oriented upward; b) supporting said wafers during said transporting step on a low-mass conveyor system comprising small diameter non-rotating refractory tubes supporting said wafers, which refractory tubes are suspended on wires spanning across the wafer processing path and which are continuously advanced through said zones at a selected rate; and c) heating said wafers directly by at least one of IR lamp radiation and thermal resistance radiation or re-radiation directed onto said top and bottom surfaces for a time sufficient to promote diffusion of dopant from said doping layer into said wafer substrate material to complete development of a p-n junction layer, a back contact layer or both said layers.