Abstract: A microwave monolithic integrated circuit includes a coplanar waveguide (CPW) formed by a composite silicon structure constituted by a relatively high resistivity substrate, a first oxide layer on the upper surface thereof, a relatively thin silicon layer formed on the surface of the first oxide layer, and a very thin second oxide layer formed on the surface of the thin silicon layer. The silicon layer and the first oxide layer on which it is formed constitutes a silicon-on-insulator or SOI structure. A metallic signal line and ground planes are bonded to the surface of the second oxide layer. The zone of the thin silicon layer which extends between the ground planes is doped with an active impurity to produce high conductivity therein. As a result, the electric component of a quasi-TEM wave traversing the waveguide is substantially restricted to the thin silicon layer and does not penetrate to the underlying bulk silicon substrate.

Abstract: A monolithic microwave integrated circuit (MMIC) is produced by a method which forms multilevel conductive members, including thick low-loss metallic members. The low-loss metallic members are particularly useful for forming inductors and interconnecting circuit components. The MMIC is formed on a thick oxide layer of a silicon-on-insulator structure having a high-resistivity silicon substrate to inhibit RF interaction with the substrate.