Deposition of Contaminants on Silicon Media During Wet Processing
The International Photovoltaic Equipment Association – IPVEA – is committed to the solar energy industry and to enabling profitable manufacturing of photovoltaic technology. Understanding that there are many steps in PV manufacturing, wet processing technology remains an economically attractive technique in the Si solar cell fabrication.
Wet process technology is used both in the front- and back-end applications and plays an exceptional role in the quest to improve yield and efficiency.
The chemicals used in wet processing applications often start with low impurities, but exposure to the materials used in the wet process system – such as iron – can very rapidly contaminate the liquids to undesirable levels and can negatively impact the efficiency and the effective life of the solar cell. This contamination is further compounded in wet benches, where chemical baths are often recirculated without the use of filtration, causing the contamination levels to grow over time.
The following paper reviews the major wet processing issues, and provides the photovoltaic manufacturer an understanding of the impacts their purity levels in their wet process baths have on their wafer. It will also help PV manufacturers to improve the purity of their wafers through better control of their wet process steps.