KINETICS AND MECHANISM OF THE ETCHING OF COSI2 IN HF-BASED SOLUTIONS

The wet etching behavior of CoSi2 films in HF-based solutions is inves tigated for a nide range of experimental conditions. It is established that the etching rate of CoSi2 depends on the concentrations of H+ io ns and on the initial concentration of HF ([HF](i)). Interaction of H and HF with the CoSi2 occurs in the adsorption layer. The concentrati on of adsorbed particles is described by the equation of the Freundlic h adsorption isotherm. The kinetic equation of the etching rate is R = k(R) Theta(H+)Theta(HF), where k(R) approximate to 2.5 . 10(7) exp (- 10500/RT) nm/s (0.416 at 293 K), Theta(H+) approximate to [H+](0.135) and Theta(HF) approximate to [HF](0.310)(i). It is shown that the indu ction period increases in the etching process of CoSi, in diluted HF, which is attributed to the presence of a thin surface layer on top of the CoSi2.