Modified silicon micromachining process with air cavities and silicon-to-air transitions for low-loss millimeter-wave antenna tape-out

In this paper, a modified silicon micromachining process is utilized to design millimeter-wave devices with air media. The modified silicon micromachining process is suitable for designing low loss air-cavity structure to mitigate dielectric loss in millimeter-wave band. However, due to the large permittivity difference between air (∊r = 1) and silicon (∊r = 11.9), a compact feeding structure is necessary to transmit energy from silicon medium to air cavity in the silicon based on-chip applications. For our demonstration purpose, a two-element slot antenna array with a compact transition structure is fabricated by using the modified silicon micromachining technique. The numerical and experimental results show that the modified silicon micromachining process technique exhibits exciting possibilities for low-loss millimeter-wave applications.