Etch rates of (100), (111) and (110) single-crystal silicon in TMAH measured in situ by laser reflectance interferometry

Laser reflectance interferometry has been used to measure in situ etch rate s of (100), (110) and (111) single-crystal silicon planes in 5-35 wt.% tetr amethyl ammonium hydroxide (TMAH) solutions. The laser reflectance method w as seen to give very accurate etch rates for samples that developed a surfa ce roughness lower than 100 nm during the experiments. The etch rate of (10 0) and (111) was found to decrease with increasing etchant concentration, w hile the highest and lowest etch rates of (110) were observed for the 25 an d 15 wt.% solutions, respectively. Activation energies were calculated as 0 .54-0.59 eV for the 20-35 wt.% solutions, about 0.54 eV for the 25-35 wt.% solutions and 0.50-0.54 eV for the 25-35 wt.% solutions for the (100), (111 ) and (110) crystal orientation, respectively. (C) 2000 Published by Elsevi er Science B.V.