Cavity profile control in DRIE process

Deep Reactive Ion Etching (DRIE) has revolutionized a wide variety of advanced package applications. Cavity etch process is an important step for fan-out wafer level package (WLP), which general fabrication by DRIE. In this paper, we investigated the influence of process parameter on the profile and etch rate in square-hole cavity etch. Sidewall angle was controlled by fluorine isotropic etch. So the sidewall angle was increased with the etch rate, which can be increased by raise source and bias power. It was shown that bias power drastically impact on sidewall angle in our study. High etch rate with optimized profile were obtained by controlling the plasma density and ions bombardment energy independently in two steps. Vertical profile was obtained when auxiliary gas was used in the Si main etching step. Based on the above learning, a cavity etch process be optimized. Both good profile and high etch rate were obtained.