Title:	High Throughput Low Energy Industrial Emitter Diffusion and Oxidation
Author(s):	M. Meßmer, S. Lohmüller, J. Weber, A. Piechulla, S. Nold, J. Horzel, A. Wolf
Keywords:	Laser Doping, Thermal Oxidation, Silicon Oxide, High Throughput, Wafer Stacks
Topic:	Silicon Materials and Cells
Subtopic:	Manufacturing & Production of Si Cells
Event:	37th European Photovoltaic Solar Energy Conference and Exhibition
Session:	2CV.1.44
Pages:	370 - 377
ISBN:	3-936338-73-6
Paper DOI:	10.4229/EUPVSEC20202020-2CV.1.44
Price:	0,00 EUR
Document(s):	paper, poster

Abstract/Summary:

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In this work, we investigate an approach of shortened low pressure (LP) POCl3 diffusion and a high throughput thermal oxidation with stacked wafers to form the emitter for passivated emitter and rear cells (PERC). As the high temperature processes such as LP-POCl3 diffusion and thermal oxidation account for a significant share of the manufacturing costs of PERC solar cells, our high throughput approach is very promising in terms of reducing both, production costs and energy consumption. Compared to state-of-the-art POCl3 diffusion and low temperature oxidation, a 40% reduction of the specific costs and a 50% reduction of the energy consumption of the high temperature processes is feasible. We examine this approach by using four different adapted LP-POCl3 diffusion processes using only the deposition phase (omitting further drive-in and in-situ oxidation) in combination with a “stack oxidation” process. Detailed characterization of the properties of the emitter and oxide layers after diffusion and after oxidation confirm a high quality emitter formation resulting in emitter dark saturation current density j0e ≈ 32 fA/cm2 at Rsh ≈ 183 Ω/sq. Although the wafers are oxidized in a stack of horizontally oriented wafers touching each neighboring wafer, a very homogeneous oxide grows resulting in high passivation quality. Further, we find that this adapted emitter diffusion process allows for effective laser doping, which is promising for selective emitter formation.