<title>Yield effects of interactions between high polymer forming metal etch processes and postetch ash processes</title>

Abstract

ABSTRACT We have demonstrated a correlation between post-metal etch ashrate performance and yield on CMOS technology integrated circuit (IC) product wafers etched at metal etch with high polymer producing recipes. Thispaper will present details of high polymer forming metal etch processes and two novel techniques developed forquantifying the amount of polymer formed during etch. Data will be presented which illustrates a correlationbetween electrical test yield, post metal etch ashrates and the amount of polymer formed during the etch. Finally,recognizing that the metal etch recipe I ashrate correlation does not explain all forms of yield loss due to leakage,we suggest other areas for investigation.Keywords: metal etch, sidewall polymer, corrosion, post-etch ash, neutral oxide etch, Hexodes, leakage. 1. INTRODUCTION Just as a metal etch engineer must concentrate on the performance of his/her etch in the traditional sense- etch profile, etch rate and oxide loss, for example, it has become apparent that he or she must also concentrateon the more subtle interactions that exist within metal etch. One of the most insidious is the interaction betweenthe amount of polymer produced during the etch and the ashrate performance of the post metal etch ash.