Millimeter-wave integrated waveguides on silicon

An integrated waveguide realized on (high resistivity) silicon using an IC-compatible process is reported in this work. The manufacturing process flow is based on substrate transfer technique and KOH etching, giving the resulting waveguide a trapezoidal cross-section. For this structure, the analysis of the propagating modes described here shows that it is possible to define a TE
₁₀
-like mode, whose field distribution strongly resembles the classical TE
₁₀
mode of a rectangular waveguide. The cut-off frequency of the first higher order mode is also analyzed for different waveguide aspect ratios (width over height). In the fundamental mode operation, extremely low losses smaller than 0.12 dB/mm up to 50 GHz and 0.3 dB/mm up to 100 GHz are obtained respectively for a waveguide with cut-off 35 GHz and 77 GHz.