Experimental Characterization of the Si/Al/Tetramethylammonium Hydroxide System

Electrochemical measurements were used to determine the open-circuit potentials (OCP) of Si/tetramethylammonium hydroxide (TMAH) and Al/Si/TMAH systems. The OCP of Al/Si/TMAH and Si/TMAH were found to be in general agreement with the results obtained by other researchers using linear sweep voltammetry. It was found that the presence of a macroscopic piece of Al electrically connected to the Si shifts the OCP of Si to a substantially more negative level (-2.1 to -2.3 V vs. the Ag/AgCl reference electrode), and reduces or stops the etch reaction of Si. This reduction of the etch reaction rate is more dramatic for n-type silicon. It was found that the native oxide on the silicon surface interferes sensitively with these measurements.