A study of the passivation peak current density for (1 0 0) oriented silicon in tetramethylammonium hydroxide (TMAH): effect of temperature, concentration and carrier type

Abstract

A detailed study into the effect of temperature and concentration on the peak current density for p- and n-type (1 0 0) oriented silicon (Si) in aqueous tetramethylammonium hydroxide (TMAH) solutions is described. The peak current density data was obtained from linear sweep voltammograms carried out at a sweep rate of 5 mV s −1. The temperature range used was 30–80 °C and the concentration range employed was 5–25 wt.% TMAH. The peak current density was found to increase with temperature for both p(1 0 0) and n(1 0 0) Si at every concentration investigated. A general decrease in the peak current density was observed with increasing concentration for the two carrier types at every temperature investigated. The effect of carrier type was also investigated and how this effect varied with concentration and temperature. Peak current density data was used to estimate the activation energy for the dissolution of the Si(1 0 0) plane in TMAH. This appears to be a valid alternative method to the use of etch rate data for estimating these activation energies. The activation energy for n(1 0 0) Si (0.600–0.616 eV) was found to be consistently higher than that of its p(1 0 0) counterpart (0.521–0.578 eV). The results presented confirm that a close relationship between the peak current density and the etch rate exists.