Title:	Macroscopic Numerical Simulation of the Ozone-Based Wet Chemical Emitter Etch Back for Alkaline Textured Si-Wafers
Author(s):	T. Dannenberg, L. Mohr, M. Zimmer
Keywords:	Simulation, Emitter Etch-Back, CFD
Topic:	Silicon Materials and Cells
Subtopic:	Manufacturing & Production of Si Cells
Event:	37th European Photovoltaic Solar Energy Conference and Exhibition
Session:	2CV.1.40
Pages:	358 - 363
ISBN:	3-936338-73-6
Paper DOI:	10.4229/EUPVSEC20202020-2CV.1.40
Price:	0,00 EUR
Document(s):	paper

Abstract/Summary:

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In photovoltaic industry, wet chemical processes are commonly used for surface structuring and cleaning purposes. The process of wet chemical emitter etch back in hydrofluoric acid (HF), hydrochloric acid (HCl) and ozone (O3) is a promising option in the formation of selective emitters, as the etch back is combined with a cleaning effect. However, surface inhomogeneities were shown in a previous work. In this work an approach for a multiphysics simulation of the emitter etch back process over a full wafer surface is made, taking into account fluid dynamics as well as reaction modeling. A microscopic two dimensional (2D) model is stepwise extended to a full industrial wafer length. Validation experiments enable an estimation of unknown parameters via parameter studies. At higher O3 concentrations simulation results are in good agreement with validation data. The developed reaction model is then transferred to a three dimensional (3D) model, to simulate etching depths over a full wafer surface. Similar mean etching depths of simulation (8.67±0.22 nm) and experiment (9.02±1.10 nm) are obtained. The model can be used as a basis for future work to enable an effective process optimization. For instance, to simulate effects as a result of parameter changes like plant design or etchant composition.