High speed spectroscopic ellipsometer for the monitoring of photoresist process

Abstract

We developed a spectroscopic ellipsometer with real-time and in situ capabilities. Data acquisition speed of less than 20 ms was achieved for a pair of ellipsometric spectra with 512 spectral points over near infrared to near ultraviolet region. When this technique was applied to the bake and exposure processes of photoresist films, the kinetic information such as thickness reduction and variation of optical properties were obtained. As a result, we could obtain Dill's exposure parameters as well as the activation energy for the soft bake process. We also proposed that ellipsometer be used as an end-point detector in order to prevent over-process such as over-exposure or over-baking.