Novel Technique of Thin Photoresist MIcromachining For Submillimeter Wave Circuits

摘要

This paper demonstrates a novel technique of microfabrication for sub-millimeter waves circuits. The proposed technique enables E-plane high Q filters, low loss transitions and directional couplers to be formed for operating frequencies above W-band. The overall processing includes realization of ultra-thin E-plane components and rectangular waveguides with a thin positive photoresist (known as SU8) onto a metal block that has been mechanically milled with standard flanges. The thickness of the E-plane substrate made with this methodology can be tailored down to a few microns. The measured insertion losses of an E-plane transmission line is typcially below 0.1 dB per millimeter and the guide wavelength was foun to be very close to the free-space wavelength. The methodology to achieve a thickness of dielectric substrate below ten microns also enables a transmission line of less than 30 ohm to realized with negligible losses. In addition, by glwing a conducting photoresist layer with precise thickness onto an oversizes waveguide channel, it is possible to attain a "re-scales" waveguide operating at submillimeter wave frequencies. In this paper, the this technique is first presented with particular reference given to the requriement of submillimeter wave applications. Our ecent measurements is then given to substrantiate the presentation.