IN-SITU CONTROL OF THE ELECTROCHEMICAL GAP HEIGHT MODIFICATION OF A SUSPENDED GATE FIELD-EFFECT TRANSISTOR BY CAPACITANCE-VOLTAGE MEASUREMENT TECHNIQUE

A technique is described to monitor in situ the variation of the gap h eight, a mechanical parameter of a microelectronic integrated circuit known as suspended gate field-effect transistor (SGFET), by electroche mical deposition of a metal layer on the gate electrode. During the de position process, the gap height was measured simultaneously starting from 800 nm down to 200 nm using the capacitance-voltage (CV) measurem ent technique. As a result of this modification, the threshold voltage has been shifted from over 10 V down to 1 V leading to a decrease of the noise level of the SGFET as well. The modified chips were electroc hemically coated with a polymer layer and used as a gas sensor for the lower ppm range. (C) 1998 Elsevier Science S.A. All rights reserved.