Kazuyuki Inoue

Effects of small amount of impurities on etching of silicon in aqueous potassium hydroxide solutions

Abstract We have investigated the etching characteristics of Si{110} planes in aqueous potassium hydroxide (KOH) solutions containing ppb-level of Cu and Pb. It is found that ppb-level of Cu roughens the silicon surface and the etching rate is changed by ppb-level of Cu and Pb. The effects of Cu and Pb can be explained by the interaction between ions and hydrogen gas generated during etching based on oxidation–reduction potentials of Cu, Pb and H.

Effect of magnesium in KOH solution on anisotropic wet etching of silicon

Etching characteristics of Si in KOH solution containing Mg are investigated. Etch rate of silicon slightly decreases by the Mg on the order of 10 ppm in 32 wt.% KOH, while the etched surface roughness does not change in contrast to Cu as an impurity. The surface roughening caused by the ppb-level of Cu in KOH solution can be fully recovered by adding Mg on the order of 10 ppm in the solution.