DEFLECTION AND MAXIMUM LOAD OF MICROFILTRATION MEMBRANE SIEVES MADE WITH SILICON MICROMACHINING

With the use of silicon micromachining, an inorganic membrane sieve fo r microfiltration has been constructed having a silicon nitride membra ne layer with thickness typically 1 mu m and perforations typically be tween 0.5 mu m and 10 mu m in diameter. As a support a [100]-silicon w afer with openings of 1000 mu m in diameter has been used. The thin si licon nitride layer is deposited on an initially dense support by mean s of a suitable chemical vapor deposition method (LPCVD). Perforations in the membrane layer are obtained with use of standard photo lithogr aphy and reactive ion etching (RIE). The deflection and maximum load o f the membrane sieves are calculated in a first approximation. Experim ents to measure the maximum load of silicon-rich silicon nitride membr anes have confirmed this approximation.