Fabrication of Deep Trenches in Silicon Wafer using DeepReactive Ion Etching with Aluminum Mask(Fabrikasi Jurang dalam pada Wafer Silikon Menggunakan Punaran Ion Reaktifdalam dengan Topeng Aluminium)

In this paper, a deep-reactive ion etching (DRIE) process for fabricating microelectromechanical system (MEMS) silicon trenches with a depth of more than 250 μm is described. The DRIE was produced in oxygen-added sulfur hexafluoride (SF6) plasma, with sample cooling to cryogenic temperature using a Plasmalab System 100 ICP 180 at different RF powers. A series of experiments were performed to determine the etch rate and selectivity of some masking materials such as resistsand metal (Al). Experiments showed that different materials have different etch rates, but for the Al mask, an etch rate of 5.44 × 10-3 nm/min was achieved, that exhibited stronger resistance against RIE than photo resists. By controlling the major parameters for plasma etch, an etch rate of 2.85 microns per minute for silicon and a high selectivity of 5.24 × 105 to the Al etch mask have been obtained. A 90 min etching experiments using etching gas SF6 of 60 standard cubic centimeters per minutes (sccm) with oxygen (13 sccm) were performed by supplying RF power of 5 W to an ICP of 600watts, and silicon etching process with a depth of 257 μm was demonstrated. Our experiments showed that Al is the best mask material for very deep trenches in silicon.