Nondestructive Characterization of RIE Induced Radiation Damage Using Surface Acoustic Wave

Abstract

AbstractReactive ion etching (RIE) is extensively used as a high resolution pattern transfer process for fabrication of silicon devices. In this work dry etching radiation damage in p-type boron doped, silicon wafers was investigated using a nondestructive surface acoustic wave (SAW) technique. The transverse acoustoelectric voltage (TAV) is monitored across the silicon wafer which is placed in proximity of a SAW delay line. TAV is developed due to the nonlinear interaction between the electric field accompanying SAW and the free carriers near the silicon surface. TAV versus bias voltage (applied across the semiconductor) was obtained to measure the flatband voltage (VFB) shift. The flatband voltage shift of the etched wafer was determined as a measure of the amount of surface charge introduced into the surface by ion bombardment. SiO2films were etched in C4F8and C2H2with 2 W/cm2input power. The ion energy was determined by the self bias dc voltage developed on the cathode. It is shown that a magnetron RF discharge introduces an order of magnitude less damage than non-magnetron discharge.