Integrated antennas and filters fabricated using micromachining techniques

Micromachined thick-metal filters and antennas have been fabricated using a subset of the LIGA micromachining process. In the LIGA (a German acronym for LIthographie, Galvanoformung, Abformung which translates to lithography, electroforming, molding in English) process, tall (5 μm-1 mm) metal structures with vertical sidewalls are very precisely fabricated on semiconductor and dielectric substrates using deep X-ray lithography and plated metal. It is expected that the micromachined thick-metal circuit elements and antennas will be used in V-band (50-75 GHz) and W-band (75-110 GHz) integrated circuit applications. For the microwave bandpass filters, the metal thickness of the LIGA process is utilized to control the capacitive coupling between adjacent microstrip lines. The measured insertion loss of the proof of principal 10 GHz filters is less than 0.2 dB and the measured fractional bandwidth is 38%. The thick metal of the LIGA micromachining process has been used in the design and fabrication of millimeter-wave tapered slotline antennas (TSA) that extend off of the edge of GaAs substrates and therefore do not lose power to trapped substrate modes in the high permittivity material. The micromachined tapered slotline antennas that are presented in this paper show substrate-mode free radiation at 94 and 184 GHz