Gripping-In-Liquid: Significant parameters for the automated handling of ultrathin substrates in cleaning baths

New photovoltaic cell concepts often involve the utilization of thin or ultra-thin silicon wafers. Future photovoltaic cells based on ultra-thin silicon wafers require an appropriate and sensitive approach for the automation of handling methods. When thinner substrates (<< 100?m) are considered, forced by cell architecture developments or new wafering technologies, new automation solutions for the cleaning of substrates may be needed. Batch processing in carriers may not work quite as well as for current wafer thicknesses (160 - 180 ?m). The challenge faced with inline processing, where applicable for cleaning, is the substrate's edge protection and continuous movement. A novel wafering method requires the cleaning of organic residues off an ultra-thin substrate in an etching bath. The paper discusses the opportunities and limits for the automated handling of single ultra-thin substrates in liquid and explains the identified significant parameters of the new handling method. The applicability and the limits of the processing parameters for underwater gripping of ultra-thin wafers as well as the opportunities for a dedicated advanced process control are presented. Acknowledgment: Part of this work was co-funded by the European Commission within the 7th Framework Program. Thanks to all partners of the SUGAR-project for the fruitful discussions and input.