Qb. Vu et al., SURFACE CHARACTERISTICS OF (100)SILICON ANISOTROPICALLY ETCHED IN AQUEOUS KOH, Journal of the Electrochemical Society, 143(4), 1996, pp. 1372-1375
Anisotropic etching with KOH has become a standard and important proce
ssing step in the fabrication of bulk micro-machined devices. The surf
ace quality of etched regions can play an Important role in device per
formance. In this paper we examine the effect of surface preparation,
wafer rotation, and wet/dry loading on the roughness of KOH etched sur
faces. In our work, over 1500 wafers have been etched. The process was
continually improved until a stable operating point was achieved. Sur
face preparation techniques were varied to determine the etch characte
r. However, despite the wide range of surface preparations tested, we
found that surface preparation had no statistically significant effect
on roughness. Instead, our results lead us to conclude that roughness
is mainly due to conditions within the KOH etching solution, and in p
articular to the hydrogen gas bubbles evolved during etching.