| abstract |
A method for micro-machining the surface of a silicon substrate (10,14) which encompasses a minimal number of processing steps. The method involves a preferential etching process in which a chlorine plasma-etching is capable of laterally etching an N+ buried layer (12) beneath the surface of the bulk substrate (10,14). Such a method is particularly suitable for forming sensing devices which include a small micro-machined element (18), such as a bridge, cantilevered beam, membrane, suspended mass or capacitive element, which is supported over a cavity (22) formed in a bulk silicon substrate (10,14). The method also permits the formation of such sensing devices on the same substrate as their controlling integrated circuits. The method can optimise the dimensional characteristics of the micro-machined element (18) or encapsulate the micro-machined element (18). |