Measurement of {111} silicon anisotropic etching activation energy

We present silicon etch rate measurements from wagon wheel patterns and widely separated V-grooves etched in KOH solutions. The data indicates there is a reactant depletion effect when using wagon wheel patterns, which obscures the true surface-reaction-rate-limited etch rate. Etch rates obtained from widely separated V-grooves, which are less influenced by reactant transport, indicate the activation energy of {111} etching is less than that of {100} etching, in contrast to previous reports. Our experiments yield activation energies of 0.53 eV for {111} planes and 0.62 eV for {100} planes. The apparent activation energy is highly sensitive to slight angular misalignments off the {111}.