KOH Hood and Bath

The hood consists of a stainless steel heated tank for the exclusive use of KOH - potassium hydroxide. The bath has a recirculation pump and filter and also ultrasonics may be used to enhance uniformity. Potassium Hydroxide (KOH) is used for selective crystallographic etching of silicon. For example, KOH will preferentially etch the <100> plane of silicon 400x faster than the <111> plane. This creates a V-etch or pyramidal cavity. The dimensions and geometry of which are dependent upon the etch mask aperture and wafers crystal orientation. LPCVD Silcon Nitride is the preferred masking material. A number of AMMT fixtures for single wafers (100 and 150mm) are available and well as fluoroware cassettes (75, 100, 150mm) so that a larger number of wafers may be processed simultaneously.