Particle filters integrated inside a silicon wafer

Abstract: A method is described to integrate particle filters inside a silicon wafer by creating pores in a recessed membrane. The filters are created in either a silicon or a silicon nitride membrane located 100μm below the wafer surface. The fabrication process involves anisotropic etching of front- and back-side of a (100) silicon wafer, deposition of a silicon nitride layer, spraycoating of photoresist and reactive ion etching of the pores. The filters may serve as a well or reaction chamber at the same time. We have patterned pore diameters in the 10–50μm range in 100μm recessed membranes that are suitable for application in stacked systems such as in an integrated inkjet nozzle. [Copyright &y& Elsevier]