Silicon Etching in CrO3 ‐  HF  Solutions: II . Low Ratios

Abstract

The dissolution of silicon in CrO3‐HF solutions with a low false[HFfalse]/false[CrO3false] ratio was investigated by etching and electrochemical measurements. Etching is seriously inhibited in comparison to solutions with a high ratio. The electrochemical measurements showed that inhibition is caused by the formation of a mixed valence chromium complex which partly blocks the surface. It has been found that a reaction between intermediates of both the reduction and the oxidation processes plays an important role in etching. A rate law for the etching kinetics is given.

Silicon Etching in HNO[sub 3]/HF Solution: Charge Balance for the Oxidation Reaction

“…A similar effect has been observed with silicon in HF solutions containing other oxidizing agents. 18,[20][21][22] Electrons from intermediates of the etching process can be thermally excited to the conduction band. Under depletion conditions, the electrons are driven from the surface, and registered as an anodic current.…”

Electrochemical and Raman-Scattering Characterizations of Defects in Polycrystalline Silicon Thin Films Formed by Excimer-Laser Annealing, Solid-Phase Crystallization, and Continuous-Wave Laser Lateral Crystallization

“…7) The enhancement of the etching rate at defects was related to electron-hole recombination centers in the band gap of Si. [8][9][10] We previously reported that the hydrogenation of ELA poly-Si suppresses the etching at GBs, 11,12) which is attributed to the passivation of dangling bonds (DBs) by hydrogen. It was also found that a high density of active defects exists in grains.…”