Micromachined components for terahertz frequency applications

lithographic technology for the fabrication of terahertz circuits, the integration of an active solid state device is explored. The device chosen for this work is the resonant tunnel diode (RTD). Some background discussion of the operation of these devices as oscillators is presented, and techniques for full integration of devices into a waveguide, using processes which are completely compatible with semiconductor manufacturing technology, are explored experimentally. Two main problems prevent the use of the terahertz frequency band (defined for present purposes as 100GHz - 10THz) in a wider range of applications. The first is the absence of a convenient, cheap solid-state source of power and the second is the significant cost of conventional passive components. In this Thesis, the second issue is addressed in detail, describing developments in the fabrication and characterisation of low cost lithographically-produced terahertz frequency passive components. An extensive study of the use of ultra-thick UV photoresists is presented, including spinning and baking process characterisation; the main thrust of the work involves positive photoresists. The conditions and problems associated with film exposure and development of these non-standard resists are also investigated. Coupling these developments with fine-feature electroplating, it is shown that rectangular metal-pipe-on-wafer metallic waveguides can be produced with dimensions and tolerances suitable for supporting frequencies up to 300GHz. Measurements are reported using vector analyser and other methods which demonstrate that waveguide and other components made by this process are suitable for use in on-chip terahertz frequency circuits. The Thesis also contains several examples of the use of an advanced negative photoresist for the fabrication of passive components, together with some discussion of the relative merits of the two approaches. To increase the potential o