Chemical Dry Etching of Si Substrate in a Discharge Flow Using Ar/CF4 Gas Mixtures

F atoms were generated by a low-power microwave discharge of various Ar/CF4 mixtures in a fast discharge flow. They were used for chemical dry etching of Si substrate at room temperature. The variation of etch rate was measured as a function of the microwave power, the Ar or CF4 flow rate, and the distance between the center of discharge and the substrate, in order to determine the optimum conditions. The maximum etch rate was about 700 Å/min at a microwave power of 80 W, an Ar flow rate of 3000 sccm, a CF4 flow rate of 70 sccm, and a distance between the center of discharge and the substrate of 10 cm. A thin CmFn polymer was deposited on the etching edge at high CF4 flow rates of 80–100 sccm.