Angular dependences of Si<inf>3</inf>N<inf>4</inf> etch rates and SiO<inf>2</inf>-to-Si<inf>3</inf>N<inf>4</inf> etch selectivity in C<inf>4</inf>F<inf>6</inf>/Ar/O<inf>2</inf>/CH<inf>2</inf>F<inf>2</inf> plasmas

Summary form only given, as follows. Si3N4films are usually used as a protecting layer of a poly silicon gate during the etching of a contact hole. An increase in the etch rates of Si3N4at its curved surface lowers the etch selectivity of SiO2with respect to Si3N4[1, 2], resulting in device failure. Therefore, it is important to control the angular dependence of Si3N4etch rates and SiO2-to-Si3N4etch selectivity. In this work, the angular dependences of the Si3N4etch rate and SiO2-to-Si3N4etch selectivity in a C4F6/Ar/O2/CH2F2plasma were investigated using a speciallydesigned Faraday cage system. The Faraday cage allowed one to control the ion-incident angles. Etching was conducted by varying the ratio of CH2F2flow rate to study a role of steadystate fluorocarbon films formed on the surface of the Si3N4substrate during etching.