Broadband Modeling Of TSV Considering Bumps

The feature size of traditional integrated circuits is approaching the physical limit,so the challenges keep getting more.If so,the development of microelectronics technology will encounter the bottleneck.Fortunately,the emergence of 3D integration technology provides a new way for the continuous improvement of semiconductors.In fact,the essence is stacking the multilayer chips in the vertical direction,which realizes the connection of electrical signals between the layers.The chip area becomes smaller and the interconnection between the chips is shorter.To improve performance,3D integration provides higher transmission bandwidth and heterogeneous integration,which greatly reduces power consumption and latency.As a key part of three-dimensional integrated interconnection,Through-Silicon Via?TSV?plays a decisive role in the overall signal transmission performance of the chip.Therefore,studying the characteristics of TSV intensively has the vital significance.In this paper,we constructed a wide-band equivalent circuit model for Ground-Signal?GS?type TSV considering the bonding bumps.First,combining the physical model of TSV,we considered the skin effect in high-frequency transmission,the Metal-Oxide-Semiconductor?MOS?effect formed between TSV and the silicon substrate,the parasitic effect induced by bump and the eddy current loss as well as proximity effects of Silicon substrate.Then the equivalent impedance and admittance parameters are extracted to construct the?-equivalent circuit model.Based on the equivalent circuit model,the parameters of S matrix are derived and calculated.The calculated results got in the frequency range of100MHz-100GHz are compared with the simulation results of the 3D High Frequency Structure Simulator?HFSS?,and it turned out that error of the return loss S₁₁ and the insertion loss S₂₁,are less than 5%,which verifies the correctness of the equivalent circuit model.We analyzed the relationship between transmission characteristics and structural parameters of TSV by using the wide-band equivalent circuit for GS-type TSV considering the bonding bumps.According to the simulation results,the smaller space between TSV and the lower height of TSV as well as bonding bumps are contributing to the better TSV transmission performance.Besides,the larger TSV radius,the low substrate doping concentration and the large bonding bumps can also improve TSV transmission performance further.According to the analysis results,the optimal solution of each parameter is obtained,and the optimal structure of TSV is constructed.Compared with the transmission characteristics of the original structure,at 100 GHz,the return loss S₁₁decreased from-9dB to-14dB,the insertion loss S₂₁ increased from-1.25dB to-0.35dB,it shows that the transmission characteristics of TSV are significantly improved.On the basis of GS-type TSV structure,the Ground-Signal-Ground?GSG?TSV structure model is established and its broadband equivalent circuit model is constructed after structure analysing.The equivalent circuit models of GSG-type TSV and GS-type TSV is used to simulate respectively,and then the difference of transmission characteristics is analyzed and compared.It is deduced that and the structure of GSG-type TSV is more suitable for high frequency transmission.By changing the insulating layer filler material,we found that the material with lower dielectric constant is beneficial to the transmission characteristics of TSV.Finally,the influence of substrate doping concentration on the transmission characteristics was analyzed,that is,the better transmission characteristics of TSV depend on the lower the doping concentration.