In the RIE-process, cations are produced from reactive gases which are accelerated with high
energy to the substrate and chemically react with the silicon. The typical RIE gasses for Si are
CF4, SF6 and BCl2 + Cl2. As seen in Figure 5, both physical and chemical reaction is taking
place. Figure 6 depicts some micro/nano structures with high aspect ration etched using RIE
process.