High-Q silicon micromachined cavity resonators at 30 GHz using the split-block technique

Bulk micromachining of silicon wafers is a promising technique for use in deep three-dimensional waveguide fabrication. Past efforts to realise a high-quality cavity resonator with such a procedure have resulted in lower than expected unloaded quality factors (Q₀). A new design for micromachined cavities is presented, that is based upon the split-block technique used in traditional waveguides. Specifically, this design solves poor contact issues involved with the final stages of fabrication encountered in previous topologies of micromachined cavities. Measurement results of four resonant modes between 30 GHz and 52 GHz for a coaxial-fed micromachined cavity are presented. These are compared with simulated values from Ansoft´s high frequency structure simulator (HFSS). A measured unloaded Q₀ of 4550 for the dominant TE₁₀₁ mode at 29.326 GHz compares very well with the simulated value of 4490.