Investigation of silicon substrate thickness effects on inductor

In this paper, the thickness of silicon substrate with backside metallization effects on the inductor performance were investigated, the experimental results showed that thinner substrate with backside metallization resulted in smaller inductance and slightly higher resonant frequency. For circular spiral inductor with substrate thickness of 50μm, the inductance L with eight turns would be degraded 22% compared to the counterpart of substrate thickness of 150μm, correspondingly, the quality factor Q fallen down 16%. The measured results also showed that the inductor performance with substrate thickness of 150μm and above has not been affected by substrate thickness. Therefore, to optimize inductor performances involves trades-off between substrate skin effect and thermal conductivity in power applications. It is believed that the demonstrated results are useful for RF integrated circuits (RFICs) design and packaging.