WET ETCHING STUDIES ON ELECTRON CYCLOTRON RESONANCE (ECR) PLASMA ENHANCED CHEMICAL VAPOR DEPOSITED SILICON NITRIDE FILMS

摘要

Silicon nitride films of various compositions have been deposited on silicon substrate by electron cyclotron resonance plasma-enhanced chemical vapor deposition (ECR-PECVD) technique from mixtures of Ar, N_2 and SiH_4 as precursors. Wet etching studies were conducted using diluted phosphoric acid and buffered oxide etch (BOE) solutions of various concentrations. The etching studies using phosphoric add were conducted in the temperature range of 70℃ to 90℃. For BOE the temperature range was 25?-55℃, The etch rate with BOE solution is much higher than with phosphoric add. The dependence of the etch rate on temperature was evaluated using Arrhenius relation. The activation energy for etching depends both on the deposition conditions of the film and on the etchant. The results indicate that the mechanism of etching with phosphoric acid is different from that with BOE solution.