The form of etch rate minima in wet chemical anisotropic etching of silicon

Etching of monocrystalline silicon in alkaline based solutions leads to a deep minimum in the etch rate crystallographically oriented along [Left angle bracket]111[Right Angle Bracket]. The details of the form of the minimum (angular dependence of the etch rate) are investigated and discussed in a framework of steps originating from spontaneous nucleation and from misorientation of the crystal face exposed to the etchant. As a result, the etch rate minimum is characterized by a narrow flat portion that reflects the density of nuclei, and the temperature dependence of the width has an activation energy equal to 1/3 of the nucleation barrier.