Room temperature inductively coupled plasma etching of InP with Cl₂ mixtures using SiO₂ and photoresist masks

We report the results of a study on the inductively coupled plasma (ICP) etching of InP at room temperature using Cl₂ mixtures (Cl₂/N₂/H₂). The impact of different process parameters, including the RF power, the ICP power, the ion-to-neutral ratio, and the chamber pressure, on the etched profile was investigated. The etch rate, selectivity, and anisotropy of the profile were depicted for each etching recipe. Two types of masks, such as SiO₂ and AZ5214 photoresist, were used in this study. The etched InP feature showed a very smooth surface (rms as low as 0.5 nm) and a relatively fast etch rate of about 450 nm/min with both masks. By adjusting the etch process and depending on the used mask, we tuned the anisotropy from about 19° to 60°. A selectivity of around 4:1 and 1:1 was obtained with SiO₂ and photoresist masks, respectively. These results demonstrate how altering the ICP process parameters could affect the etching characteristics and profile.