High-Q microstrip-fed bulk micromachined silicon cavities

Bulk micromachining of silicon wafers to fabricate rectangular waveguide components has been the focus of much research over the past decade. Over that time, a number of different fabrication techniques have been presented. However, for resonator applications, these fabricated topologies restrict the cavity height to less than two wafer thicknesses. To allow for much deeper cavities, an enabling fabrication procedure for micromachined waveguide components has been proposed. In this paper, a regular height bulk silicon micromachined cavity of constant cross section, fed using a microstrip line, has been presented. The relatively low measured Q/sub 0/ factor for this cavity was due to the poor soldered connections between the top and bottom plates. A new enabling micromachined cavity design has also been introduced, which achieves a very high unloaded (Q/sub 0//spl cong/4500, measured) quality factor.