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CHARACTERIZATION OF POROUS SILICON FOR APPLICATIONS IN HIGH FREQUENCY CIRCUITS AND INTERCONNECTS

Graduate Researcher: Isaac Itotia

     Porous silicon has the to potential to allow the integration of IC and RF technologies on a single substrate. Additionally this material is complementary to post-processing of CMOS and MEMs fabrication. Understanding its high frequency behavior can provide an important bridge in our current knowledge of this material at RF frequencies.                                                                                                                                              

     This research investigates the effect of material properties such as porosity, thickness, doping, and bulk substrates on high frequency circuit performance. Transmission line properties on CPW are being studied to develop comprehensive understanding of this material for high frequency applications. Preliminary results have shown that using porous silicon on an underlying low resistivity substrates the attenuation on these substrates can be significantly reduced from about 20 dB/cm for the low resistivity substrates to about 5 dB/cm (at 50 GHz) thus brining its attenuation closer to that of high resistivity silicon. This in turn provides one with a substrate that can be used in the integration of IC and RF circuits. 

Figure 1 Cross sectional view of a CPW on porous silicon with an underlying bulk substrate along with a scanning electron microscope (SEM) picture of a fabricated sample