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


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.