Development of a MEMS fabrication process for self-assembly of on-chip antennas

This thesis describes the development of a fabrication process for building efficient 60 GHz on-chip antennas. Using a polymer micromachining process, a self-assembly method was developed to vertically raise the antennas. Vertical on-chip antennas can offer higher efficiency compared to planar antennas. The self-assembly method provides flexibility to create three-dimensional structures with different shapes. The curl and the direction of self-assembled curved structures can be controlled with simple changes in the design layout. The fabrication process uses SU-8 polymer and the antennas are fabricated by coating the self-assembled polymer structures with metal. Micromachining using polymers is inexpensive, fast, and useful for a CMOS compatible MEMS fabrication process because most processing steps do not involve very high processing temperatures. This fabrication process can be completed within a day using university-level cleanroom equipment. This fast turnaround time makes the fabrication process ideal for prototyping antennas and other three-dimensional MEMS devices. Several fabrication processes were developed and tested during the research. Many of the advances focused on making efficient on-chip antennas while keeping the cost and time for fabrication low by using the polymer micromachining. A thick dielectric layer of SU-8 was used to increase the efficiency of the antennas by increasing the spacing between the more lossy CMOS substrate and the metallic antennas. The associated transmission lines were fabricated on the dielectric layer with a patterned metal layer. The self-assembled SU-8 antenna structures were coated by metal layers on each side to cover the whole antenna structures with an even thickness.