High-performance millimeter-wave silicon varactors

Most varactors used in millimeter-wave components have been GaAs devices. We have developed planar silicon P-N junction varactors whose rf performance exceeds or compares favorably to the best available GaAs devices. This advance has been made possible primarily due to low-temperature ( < 1000°C) precision fabrication processes which allow minimization of undesirable device parasitics. The varactor fabrication process utilizes ion-beam machining and ion-implantation, combined with the best state of the art in silicon epitaxy. The toatl device process is a batch process with unprecedented uniformity and reproducibility.