Title:	Fast Alkaline Etching of Monocrystalline Wafers in KOH/CHX
Author(s):	K. Birmann, M. Zimmer, J. Rentsch
Keywords:	Etching, Analytics, Texturisation, Texturization
Topic:	Wafer-Based Silicon Solar Cells and Materials Technology
Subtopic:	Mono- and Multicrystalline Silicon Cells and Materials, Processing Technology of
Event:	23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain
Session:	2CV.5.8
Pages:	1608 - 1611
ISBN:	3-936338-24-8
Paper DOI:	10.4229/23rdEUPVSEC2008-2CV.5.8
Price:	0,00 EUR
Document(s):	paper

Abstract/Summary:

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Alkaline anisotropic etching with potassium hydroxide (KOH) and the additive 2-propanol (IPA) is a widely used step to texture monocrystalline silicon wafers industrially in order to reduce their reflection. Using IPA as an additive to KOH (aq) a texturing time of at least 20 min is required in order to remove the saw damage and to receive a texture with complete random pyramid coverage. A shorter texturing time, i.e. fast etching, would allow an increasing capacity of the etching plant and offers the possibility to use inline systems for anisotropic etching of monocrystalline silicon wafers. This study shows that the patent pending texturing process using KOH (aq) and 1,4 cyclohexanediol (CHX) fulfils these requirements and results in an appropriate surface texture within 10 min. The analytic of CHX is given. Additionally, when CHX is used overall chemistry consumption is lowered due to the higher boiling temperature of the additive; hence no redosing of CHX is necessary. Further this study aims to simulate a long-term alkaline batch process with rising silicon content in the solution.