Low-loss shielded through-silicon vias filled with multi-walled carbon nanotube bundle

In this paper, the multi-walled carbon nanotube bundle (MWCNTB) based shielded through-silicon via (S-TSV) is proposed and the compact expression for the equivalent conductivity of MWCNTB (sigma(MWCNTB)) is deduced to calculate the resistance of MWCNTB based S-TSV (MS-TSV). Then, the electrical characteristics including the S parameters, attenuation constant and time delay are investigated. The results indicate that |S-21| of MS-TSV increases with the increase of the outermost diameter of MWCNT and decrease of the thickness of the shielding layer. Compared with the copper filled S-TSV (CuS-TSV), the MS-TSV has a larger |S-21|, smaller attenuation and shorter time delay. Finally, the impact of the geometrical parameters on the conductivity of MS-TSV is analyzed. Also, the minimum packing density of MWCNTB satisfying sigma(MWCNTB)>=sigma(Cu) has been deduced. The results show that the outermost diameter of MWCNT has the most significant impact on the conductivity of MSTSV, and thicker MWCNT is helpful to increase the conductivity of MS-TSV, decrease the packing density of MWCNTB and reduce manufacturing difficulty.