Study of gate oxide breakdown caused by charge buildup during dry etching

Abstract

Charge buildup and its effect on gate oxide breakdown have been studied for several types of etchers. In a barrel asher, the charging polarity during plasma treatment depends on the direction of the Si wafer with respect to electric fields. In a magnetron reactive ion etching and an electron cyclotron resonance (ECR) etcher, gate electrodes are positively charged. In the ECR etcher, the charge buildup depends on the frequency of the radio-frequency generator connected to the wafer stage. The gate oxide breakdown during plasma treatment strongly depends on the charging polarity. A simple model is presented to successfully explain the phenomena with respect to gate oxide breakdown by charge buildup, and it is shown that gate oxide breakdown can be predicted by measuring the ΔVFB of the metal/silicon nitride/silicon dioxide/silicon capacitor and the time dependent dielectric breakdown characteristics of the gate oxide.