PROCESSING OF 3-DIMENSIONAL MICROSTRUCTURES USING MACROPOROUS N-TYPE SILICON

A process for micromachining arbitrary structures with high aspect rat ios in bulk silicon utilizing standard microelectronic processes is pr esented. It is based on electrochemical macropore formation on n-type silicon in electrolytes containing hydrofluoric acid. Very regular por e arrays with pore diameters and distances in the micrometer range and pore lengths of several hundred micrometers can be produced with this technique. Wafers with suitable prefabricated pore arrays are used as substrates for a micromachining process including anisotropic etching of very deep structures yielding straight walls to depths of as much as 150 mu m.