Wet Chemical Cleaning for Industrial Application

The wet chemical cleaning of wafer surfaces is required after several process steps in current state-of-the-art silicon solar cell production technology. Apart from the cleaning efficiency, process stability, cost, and throughput considerations have to be met. The goal of this chapter is to introduce and discuss the most common cleaning techniques within the current and potential future solar cell process sequences. An important part when discussion wafer cleaning technology is contamination: what kind of contamination is present at which step and what are the consequences for the single process steps and the overall production chain. Hence, we introduce the concept of "contamination management"—referring to the knowledge of the main contamination sources and its variations as basis for a deeper understanding for process variation and also process optimization. As literature on the topic is relatively rare, we provide experimental examples that may be used as starting point for further studies. Also, the provided techniques and data may be used to introduce contamination monitoring procedures in the industrial production environment. In a last section, we will discuss the relevance of cost for the ongoing evolution in wet chemical production technology.