In this thesis, Si-based materials were etched in various fluorocarbon plasmas, and the etch characteristics in plasma were investigated using PFCs and alternative compounds as a PFC replacement. The etch characteristics of each plasma were analyzed based on the angular dependence of the etch rates using a Faraday cage, which can be used to control the ion-incident angles. Fluorocarbon plasma was used in various applications by fabricating a superhydrophobic surface. The subjects of this thesis can be grouped into the following three categories.
(1) SiO2 and Si3N4 were etched, and the etch characteristics were analyzed, in various PFC plasmas. Based on the angular dependence of SiO2 etch rates with bias voltages in CF4, C2F6, and C4F8 plasmas, the relationship between the etch yield and steady-state fluorocarbon film was studied. The etch yield of Si3N4 was observed based on angular dependence of etch rates at various flow rates of CH2F2 in C4F6/CH2F2/O2/Ar plasmas.
(2) To replace PFC with a lower-GWP etchant, heptafluoropropyl methyl ether (HFE-347mcc3) and perfluoropropyl vinyl ether (PPVE), which are substances in hydrofluoroether and perfluoroalkyl-vinyl-ether, were used as fluorocarbon plasma precursors to etch SiO2. The etch rates of the SiO2 at various ion-incident angles in HFE-347mcc3/Ar and C4F8/Ar plasmas were compared with each other, and the etch mechanisms were identified based on the change in etch yields. PPVE/Ar plasma was compared with HFE-347mcc3/Ar plasma with regard to the SiO2 etch rate as a function of the bias voltage, and the characteristics of the steady-state fluorocarbon film formed on the SiO2 in both plasmas were investigated.
(3) The fabrication of a superhydrophobic Si surface was achieved using a cyclic etch process consisting of alternating deposition and etch steps in fluorocarbon plasma. The wetting behavior of the microscale rods on theSi surface was explained through a combination of the Wenzel and Cassie-Baxter models. A superhydrophobic Si surface with a contact angle of 165° was successfully achieved through a combination of microscale rod structures and the deposition of a fluorocarbon film.