A study of the undercutting characteristics in the TMAH-IPA system

Abstract
A new etching system of tetramethyl ammonium hydroxide-2-propanol (TMAH-IPA) is suggested. The undercutting ratio for TMAH at 80 degrees C is about 7, much higher than for KOH etchants. The addition of IPA in the TMAH system maintains the main features of TMAH and reduces the undercutting ratio by a factor of 2-3.