Effect of DRIE on the Structure of Si based Filtration Pore Arrays Fabricated with Double Side Aluminium Coating Layer

This paper reports the effect of DRIE process performed to define silicon filtration passageway underneath the aluminium based uniform pore filtration membrane and the membrane cavity on the back end of the silicon substrate. The aluminium based pore arrays for filtration is fabricated on top of the bare silicon substrate with uniform pore size and pore-to-pore gap at cryogenic temperature DRIE. Initially, the aluminium layer is sputtered on both end surface as a foundation of uniform pore arrays structure fabrication and as a DRIE mask for filtration membrane cavity on the back. Both aluminium based uniform pore filtration membrane with underneath silicon etch depth and its filtration cavity structure on the back are observed after 10 minutes and 1 h 45 minutes of DRIE process respectively. The silicon etch rate selectivity over aluminium is evaluated by verifying it's etch depth after the DRIE process. The etched area of silicon substrate underneath the fabricated aluminium based pore filtration membrane is then performs as filtration passageway when it unites with etched silicon area conducted for filtration cavity structure which started from the back end of the silicon substrate. All results have been verified by optical microscope and scanning electron microscopy. The result of the study should be beneficiary for the development of a reproducible filtration membrane with uniform pore that able to separate waste from required nutrients based on molecule size.