Negative potential dissolution (NPD)-advanced and rapid texturing method of as-cut silicon

Abstract

Texturing of as-cut p-type boron doped (1 1 1) oriented silicon has been carried out by negative potential dissolution (NPD) in KOH solutions in the dark. The use of KOH in concentrations of 16–32 wt.% results in massive silicon texturing with a formation of coined triangles pits morphology. This morphology can be formed within a short etching time of less than a minute. At higher KOH concentrations (50 wt.% KOH) and under similar conditions as-cut silicon surface is being polished. NPD current–time profile has a distinguished “U” shape. Detailed mechanism accounting for NPD texturing is provided explaining this characteristic. NPD process allows a rapid etching of as-cut (1 1 1) p-type silicon by a factor of 100, compared with etching rate at OCP. NPD allows the texturing of silicon within a very short period of time once the potentials are more negative than −10 V. As the potential is further negatively shifted, silicon etch-rate increases, as well. NPD also provides a marked distinguish between two processes: texturing and polishing; a transformation between texturing and polishing is feasible once.