Fabrication of a beam-mass structure using single-step electrochemical etching for micro structures (SEEMS)

This paper presents a new wet etching technique for micromachining called single-step electrochemical etching for micro structures (SEEMS), which is based on electrochemical etching in hydrofluoric acid. During the etching, the shape of the etched structure can be controlled by changing the light intensity. Several problems involved in the SEEMS process had to be solved. The two main problems are. firstly, that over-etching can be seen at the clamping point of the free standing beam and, secondly, it is difficult to remove large areas. These problems can be considerably reduced by an improved mask layout and a perforated mass supported by a single cantilever can be achieved. In addition, a new initial pit formation is demonstrated to make structures which are free from crystal orientation of silicon substrate.