Highly Ordered Microscale-Pyramidal-Structure-Arrayed Silicon Membranes for Filter Applications

Microscale-pyramidal-structure-arrayed patterned silicon membranes are manufactured using semiconductor processes and potassium hydroxide (KOH) etching techniques for filter applications. The silicon nitride on silicon on the insulator wafer functions as a masking layer, and the roughness of the silicon (100) plane strongly depends on the etching temperature and KOH concentration. To fabricate the membrane filter, a series of dry and wet etching using 45 wt% KOH solutions at the constant temperature of 70 °C was performed. With the dry and wet etching, micro-pyramidal arrays with 300 μm top and 16-20 μm bottom opening sizes were created. The morphological structures were analyzed using scanning electron microscopy. The manufactured membranes were tested as optical directional filters and particle filters.