This study examined the influence of the chlorine-based inductively-coupled plasma (ICP) dry etch system on Mo sidewall profile and etch rate. A sidewall angle of 14.8° to 85.0° was achieved by changing the radiofrequency (RF) and ICP power, chamber pressure, and mixed gas flow ratio during the ICP dry etching process. The experiment results show that the Mo sidewall profile can be controlled over a wide range, and the etching rate can be adjusted between 148 and 232 nm/min. Therefore, this study provides a helpful process guideline for fabricating thin-film bulk acoustic resonator (FBAR) devices.