KOH wet etching technique for patterned formation on surface of quartz crystal with AuPd mask

Abstract

Surface patterning is one of importance aspect in the development of a QCM biosensor. This paper describes a method by which a KOH (Potassium Hydroxide) etchant is utilized for the pattern formation on the surface of the quartz crystal sensor. The etching process is preferable in order to produce a flat surface roughness. The etchant concentration affects etching rate and surface roughness. In this experiment, the effect of etchant concentration on the etching rate and surface roughness was investigated. The etching of the quartz crystal was carried out using KOH concentration of 25 %, 30% and 35 % by weight at a temperature of 80°C for 2 hours. Aurum palladium (AuPd) was used as a mask to protect the rest of the quartz crystal. The AuPd mask was coated on the quartz crystal by a sputter coater in a high vacuum chamber. The etched surfaces were observed using a white light profilometer TMS 1200. The results show that best anisotropic patterns formation were obtained in 30% wt KOH solution. Furthermore, the TMS indicates that the surface roughness of the etched surface tends to increase with the increasing of KOH concentration.