Temperature measurements of glass substrates during plasma etching

Abstract

A technique based on monitoring the thermal expansion of transparent substrates by laser interferometry has been developed to measure glass substrate temperatures during plasma etching of thin film integrated circuits. Using this technique the dependence of substrate temperature on applied rf power and time in the plasma has been determined for O2, N2, and wet air plasmas under conditions of constant pressure and gas flow rate. The effect of a metallic etch tunnel on substrate temperature is also reported. Compared with conventional thermometry methods, the interferometry technique is simple, accurate, noncontacting, and does not require modifications to the plasma system and/or the substrate material.