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 s ingle-step electrochemical etching for micro structures (SEEMS), which is b ased on electrochemical etching in hydrofluoric acid. During the etching, t he shape of the etched structure can be controlled by changing the light in tensity. Several problems involved in the SEEMS process had to be solved. T he two main problems are. firstly, that over-etching can be seen at the cla mping point of the free standing beam and, secondly, it is difficult to rem ove large areas. These problems can be considerably reduced by an improved mask layout and a perforated mass supported by a single cantilever can be a chieved. In addition, a new initial pit formation is demonstrated to make s tructures which are free from crystal orientation of silicon substrate.