  With the evolution of radio frequency (RF)/microwave technology, there is a
demand for circuits which are able to meet highly challenging RF frontend
specifications. Silicon-on-insulator (SOI) technology is one of the leading
platforms for upcoming wireless generation. The degradation of performance due
to substrate coupling is a key problem to address for telecommunication
circuits, especially for the high throw count switches in RF frontends. In this
context, a novel technique for local substrate removal is developed to
fabricate membranes of mm-sized RF switch which allows for total etching of
silicon handler. RF characterization of membranes reveal a superior linearity
performance with lowering of 2nd harmonic by 17.7 dB and improvement in
insertion losses by 0.38 dB in comparison with High-Resistivity SOI substrates.
This improvement leads to a significant increase in frontend efficiency. These
results demonstrate a new route for optimization of circuit performance using
post-fabrication substrate processing techniques.
