Three-dimensional on-chip conical spiral antennas on video-monitored micromachined (100) silicon wafers

We report realization of 3-D conical spiral structures on Si-based membranes suitable for on-chip antenna fabrication. The floating broadband coplanar waveguide (CPW)-fed spiral on-chip antenna is designed for unlicensed 60 GHz band. With a novel video monitoring technique, thin membranes for antenna substrate are realized. Chromium has been used for antenna conducting parts and patterned using standard photolithography. Finally the sample is immersed in KOH solution. Thin silicon membrane is then removed, and the conical spiral antenna is realized.