Gas-liquid phase-detection and liquid film thickness measurement on a sprayed surface with a two-fluid jet using a fiber-optic probe and laser displacement sensor

Abstract

The two-fluid jet method, which impacted droplets accelerated by a high-speed air stream, is widely used in cleaning the semiconductor manufacturing process. A wafer must always be covered with a liquid film during the cleaning process because local drying may cause some defects. However, the liquid film thickness formed by the high-speed airflow and droplets and whether a liquid film exists on the impingement surface have not been investigated. In this study, we tried to measure the liquid film thickness using an optical fiber probe and a laser displacement meter. We discuss the return light signal from the optical fiber probe installed on the surface irradiating the two-fluid jet.