On etching very narrow grooves in silicon

Abstract

The etch rate on the {110} is shown to be at least 400 times faster than that on the {111} using 44% KOH : H₂O at a temperature of 85 °C and below. A model is presented which attributes essentially all the etching on the near {111} planes to the misorientation ledges. Grooves of 0.6−μm width and 44−μm depth have been produced. Such grooves have been used to make high−value SiO₂ capacitors and vertical multijunction solar cells.