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