Low-Characteristic-Impedance Transmission Line of a Benzocyclobutene- Based 3-Dimensional Structure at Millimeter-Wave Frequencies

A variety of three-dimensional (3-D) transmission line structures were fabricated using lowdielectric-constant benzocyclobutene (BCB) interlayers to achieve low characteristic impedances(Zo) at millimeter wave frequencies. The eects of structural variations on the Zo of the transmissionline structures were examined at a frequency of 50 GHz. Two dierent 3-D coplanar waveguide(CPW) structures, the bottom-ground and the double-ground structures, showed very low Zo valuesof 7.3 and 9.4, respectively, at a signal linewidth of 100 m and a bottom-ground spacingof 20 m. When the ratio of the spacing of bottom-ground width to the signal linewidth becamegreater than 2.5, the Zo was nearly saturated, showing a minimum Zo. The thin-lm microstriplines fabricated using the BCB inter layers showed a higher minimum Zo of 25.5at a groundplane width of 55 m and a signal linewidth of 35 m than the 3-D CPW structures did. Among the3-D transmission structures, the bottom-ground CPW was shown to be the most ecient structureto achieve a low Zo by maximizing the capacitance between the signal and the ground lines at 50GHz. A variety of three-dimensional (3-D) transmission line structures were fabricated using lowdielectric- constant benzocyclobutene (BCB) interlayers to achieve low characteristic impedances (Zo) at millimeter wave frequencies. The eects of structural variations on the Zo of the transmission line structures were examined at a frequency of 50 GHz. Two dierent 3-D coplanar waveguide (CPW) structures, the bottom-ground and the double-ground structures, showed very low Zo values of 7.3 and 9.4 , respectively, at a signal linewidth of 100 m and a bottom-ground spacing of 20 m. When the ratio of the spacing of bottom-ground width to the signal linewidth became greater than 2.5, the Zo was nearly saturated, showing a minimum Zo. The thin-lm microstrip lines fabricated using the BCB inter layers showed a higher minimum Zo of 25.5 at a ground plane width of 55 m and a signal linewidth of 35 m than the 3-D CPW structures did. Among the 3-D transmission structures, the bottom-ground CPW was shown to be the most ecient structure to achieve a low Zo by maximizing the capacitance between the signal and the ground lines at 50 GHz. KCI Citation Count: 2