Abstract: Reactive ion etching (RIE) of silicon was performed with SF6+O2 as etching gas under the reaction pressure of 275 m(torr). Through changing the Radio-Frequency (RF) power and the etching gas flow rate, we study and optimize the reactive ion etching process conditions. The RF power at 120 W and the flow rate of SF6 and O2 at 36 sccm and 6 sccm were identified as the optimized etching conditions. Under the conditions, the most important etching parameters were obtained with the etching rate as 1036 nm/min, the selectivity to oxide as 56.6 and the uniformity as 4.41。