Silicon interconnects for millimetre wave circuits

Recently high resistivity silicon (HRS) has been reported as an alternative to Gallium Arsenide as a high frequency MMIC foundry material. By employing aluminium metallized high resistivity silicon as a multilayer low cost interconnect medium passive structure (eg antennas, filters etc) can be fabricated at microwave and millimetre wavelengths. This paper demonstrates that thin metallization of aluminium can yield acceptable performance as coplanar waveguide circuit interconnects and can be used for direct circuit realization. A circuit example of the use of 1 μm aluminium metallization for the patterning antenna resonator is described. Various measurement issues are elaborated including the problem of contact resistance due to oxidation of the aluminium metallization.