EXPERIMENTAL INVESTIGATIONS OF ANISOTROPIC ETCHING OF SI IN TETRAMETHYL AMMONIUM HYDROXIDE

Anisotropic etching of silicon in tetramethyl ammonium hydroxide (TMAH ) is receiving attention as a relatively nontoxic alternative anisotro pic etchant for silicon (Si), for the fabrication of microelectromecha nical systems, sensors, and actuators. This work presents experimental investigations on several aspects of anisotropic etching of Si in TMA H. The effects of temperature and concentration on etch rates of {100} and {110} wafers are characterized. Several previously unreported exp erimental findings aimed at better understanding the atomic level mech anisms are presented: underetch-rate variation with mask-edge deviatio n, an investigation of stirring, and a subtle effect of applied bendin g stress.