Study On System Design And Integrated Manufacturing Method Of High-Performance Interposer

With the development of the internet of things,smart terminals,and industrial intelligence,electronic devices with high-density integration,multi-function and low power consumption has become an urgent demand.In recent years,the size reduction of the chip in the plane has become very difficult,but the emergence of three-dimensional integrated packaging technology has brought a revolutionary solution.TSV silicon interposer technology is a highly feasible solution for 3D integrated packaging technology.The TSV silicon interposer can carry and connect multiple homogenous or heterogeneous chips to realize the expansion of similar chips or the integration of multiple functional chips.Although the silicon interposer technology has many advantages,there are still some unfavorable factors,including complicated processes,high manufacturing costs and immature key processes,which significantly restrict the application and development of the interposer.In order to simplify the manufacturing processes of the interposer,reduce the costs,and solve the leakage problem of the interposer TSV and low equivalent thermal conductivity,this paper proposes a high-performance,low-cost integrated interposer manufacturing method,and studies systematically the design and verification,manufacturing process,and tested method of the interposer,combined with the application example of interposer storage expansion.The main research contents of this paper include the following aspects:Firstly,combined with the example storage expansion of interposer,the influence of common design parameters on the performance of the interposer was analyzed by the finite element simulation,and the general conclusions and design suggestions on the design parameters of the relevant silicon interposer were proposed and discussed.Specifically,the effects of TSV aperture,aspect ratio,tilt angle,pitch and insulation thickness on TSV thermal stress were studied.The effects of silicon substrate thickness,RDL thickness and dielectric material on the warping of the interposer were studied.The method of reducing the warping of the adapter plate was studied.The effects of TSV number,silicon base thickness,RDL layer thickness,dielectric material and wiring density on the heat dissipation performance of the adapter board were studied.The transmission characteristics,crosstalk and eye diagram analysis were used to verify the signal integrity of the interposer storage expansion.Secondly,based on the conventional process,this paper proposes a high-performance,low-cost silicon interposer manufacturing process,studies key processes including through-hole etching,double-sided dry film through-hole plating and high-density wiring,and fabricates a sample of the storage expansion interposer.The process uses a thin wafer as a substrate,and the TSV is filled by double-sided dry film via plating after a through hole is formed on the substrate,so that the TSV and the first layer wiring are simultaneously formed,and finally the electroplated copper and the spin-coated PI are used to prepare the multilayer RDL.This method eliminates the need for CMP removal of copper plating,backside thinning,backside preparation of insulating layers,backside exposed copper,temporary bonding/debonding,and front and back preparation of the first layer of RDL/pad,which greatly simplifies the processes,shortens the process cycle,reduces the process costs by at least 40%and the probability of defects,and improves the reliability of the interposer.At the same time,the new process eliminates the process steps that are prone to TSV leakage defects and provides excellent TSV insulation.Once again,a complete solution for the interposer tests was established and the relevant tested methods and equipment were discussed.The storage expansion interposer was thoroughly tested and the results were analyzed to investigate the feasibility of the new manufacturing method and verify its advantages over conventional manufacturing methods.The main tested results are as follows:TSV plating process is stable,TSV yield reaches 99.91%;TSV leakage current is 2.05×10^-14A,which is much smaller than the reported level;after 200 temperature cycles,the average resistance change of the interposer conductive path is within 1%,and no obvious failure occurs;the RDL wiring on the interposer is all turned on,and the resistance test value and the theoretical error are within 5%,which meets the application requirements of the storage expansion interposer.These results show that the interposer samples have high reliability and excellent performance.In addition,for the problem of low equivalent thermal conductivity of the interposer,a high thermal conductivity RDL medium was developed and its influence on the interposer was analyzed.Specifically,a diamond nanoparticle/SiC whisker/PI modified composite was proposed,and its preparation method and properties were studied.The composite is suitable for the spin coating process for the fabrication of RDL with a thermal conductivity of 1.63 W/m·K and a thermal expansion coefficient of 16.7 ppm/°C compared to PI?thermal conductivity of 0.19 W/m·K,thermal expansion?.The coefficient is 55.6 ppm/°C)and the material properties have been significantly improved.The influence of high thermal conductivity RDL media on the interposer is analyzed by finite element simulation.The simulation results show that the modified PI composite media RDL can significantly reduce the thermal resistance,the thermal stress and warping of the interposer.Finally,a thin-film through-hole TSV layout board manufacturing process and high thermal conductivity RDL are combined to propose a low-cost,high-performance interposer integrated manufacturing method,and a corresponding storage expansion interposer sample is prepared.The thermal performance test shows that after the integration of high thermal conductivity RDL,the maximum temperature on the interposer is reduced from 64°C to 45.1°C,and the maximum temperature difference is reduced from 46.6°C to 26.8°C.Through the above research,this paper establishes a complete interposer integrated manufacturing method,which realizes low cost,low TSV leakage current,high thermal conductivity and small warping.The manufacture of the curved interposer provides a new idea for the integrated manufacturing of the interposer,and is expected to become a widely used three-dimensional packaging technology.