The interest of 5G in centimeter and millimeter waves relies on large blocks of available spectra and thus increased bandwidth. At these frequencies, the dielectric and conductive losses of the substrate can greatly degrade the performances of RF circuits. With high electrical resistivity and low relative permittivity, porous silicon is an ideal candidate as a high-quality RF substrate. This paper presents an innovative technique of post device fabrication integration of porous silicon (POST-PSi) with the substrate. The frontside is not involved in porous layer growth and therefore the integrity of the RF circuitry is not impacted by the POST-PSi process. A comparison of the RF performances with benchmark trap-rich (TR) RF silicon substrate is presented. In addition to its compatibility with standard microfabrication processes and stable final structure, POST-PSi provides characteristics of low losses, high isolation and very high linearity, unmatched by any other silicon-based substrate. Finally, the substrate’s RF performance is evaluated at high temperature, and POST-PSi substrate linearity is shown to remain sufficiently high for RF and 5G applications up to 175 °C.

5G对厘米波和毫米波的兴趣取决于大量可用频谱，因而增加了带宽。在这些频率下，基板的介电和导电损耗会大大降低RF电路的性能。具有高电阻率和低相对介电常数的多孔硅是高质量RF衬底的理想选择。本文提出了一种创新技术，可将多孔硅（POST-PSi）与基板进行后期设备制造集成。正面不参与多孔层的生长，因此RF电路的完整性不受POST-PSi工艺的影响。给出了射频性能与基准富陷阱（TR）射频硅衬底的比较。POST-PSi除了可以兼容标准的微细加工工艺和稳定的最终结构外，还具有损耗低，隔离度高和线性度高的特点，这是任何其他基于硅的基板所无法比拟的。最后，在高温下评估了基板的RF性能，并且显示POST-PSi基板线性度对于175°C以下的RF和5G应用而言仍然保持足够高。