Interferometric techniques for dielectric trench etch applications

In this paper, we present an in-situ interferometric technique to control the trench depth for etching various type of patterned dielectric films, including silicon oxide, low-k black diamond, and low k SILK materials. We present the data on etching oxide trench wafers with various pattern density on Si substrate, black diamond film on Si, and SILK on Si, using Applied Materials' MERIE dielectric etch chambers. A good correlation between predicted etch depth using interferometric signals and SEM depth data is presented. In addition, the issues of integrating this sensor into a dielectric etch chamber are addressed.