Simulation of inverse reactive ion etching lag

Abstract

Inverse reactive ion etching (RIE) lag was considered by a proposed model, which includes processes of adsorption, heterogeneous reactions, desorption, activation, sputtering, and stochastic mixing. Inverse RIE lag was explained by considering the neutral flux distribution at the groove bottom and assuming that arrival of C atoms from a plasma retards etching by causing surface passivation, whereas ion bombardment leads to etching. The thickness and composition of the altered layer at different points of groove during silicon etching in a fluorocarbon plasma were calculated. It was found that thickness of the altered layer increases with the increase of the microstructure width due to increased flux of C atoms at the groove bottom. Increased concentration of C atoms at the groove bottom reduces etching rate in the vertical direction.