Effect of wet chemical treatment on BK-7 substrate

Surface cleanness and roughness to BK-7 substrates are important factors affecting the performance of laser optics. The conventional RCA cleaning method is widely used in removing particles from substrate surface, with high removal efficiency but rough surface. Therefore, more precise control of the chemical cleaning performance of BK-7 substrate is required than what is available today. In this study, four groups of BK-7 samples were dealt with different cleaning treatments to explore the effects of chemical solutions. The influences of chemical solutions on removal efficiency, etching depth and surface roughness were studied. An optimal cleaning method of BK-7 substrates was proposed, which could remove contaminations completely and gets smoother surface.