A Spectroscopic Monitor for Sputter-Etching Processes

Abstract
Sputter-etching is a convenient technique for metal pattern generation on complex integrated circuits. It is particularly advantageous for multimetal systems because it completely eliminates the possibility of undercutting of the lower metal layers as can occur with chemical etching. A real-time monitoring system has been developed for monitoring the sputter-etching process when it is used for metal pattern generation with a beam lead metallization system consisting of titanium, platinum (or palladium), and gold. The intensity of the uv atomic radiation emitted by sputter-etched atoms which are excited in the sputtering discharge is monitored. The system has been used with both triode and diode types of sputter-etching systems and can reliably be used to tell when a given metal layer has been completely removed. A detailed description of the monitoring system and its performance is given.