Multi-field Analysis Of Through-Silicon Via (TSV) Links In 3D ICs

With the development of semiconductor technologies,feature size has been reduced and more challenges have been posed to the Moore’s law.To continue the Moore’s law,more people began to turn their attention to TSV based 3D ICs.TSV based 3D ICs can achieve shorter interconnects through metal filled TSVs resulting in lower latency and lower power consumption,and higher integrated density can be achieved by vertically stacking different layers resulting in greater electrical performance.While,there are some problems in reliability such as heat dissipation and thermal stress that have not yet been solved,which seriously hindered the development of TSV based 3D ICs.In this thesis,we mainly studied the performance of the TSV based 3D ICs with different structural of TSVs and lines in RDL layers from electric field,thermal field and stress field.The work and results obtained in this thesis are listed below: 1.A high frequency impedance model based by RLCG model of four cylindrical series of TSV is proposed in this thesis.The resistance and inductance of cylindrical TSV can be obtained according to the traditional transmission line model,and the capacitance considering MOS effect is obtained based on the coaxial capacitance formula.The thickness of the insulating layer in the coaxial TSV affects the capacitance and increases the loss.The central hole changes the DC resistance and self-inductance,but it almost does not affect the loss in high frequency.Double annular TSV has the metal shield and the central hole at the same time,and it has the characteristics of coaxial TSV and annular TSV.2.The electrical characteristics of microstrip line,coplanar waveguide,coplanar strip line and strip line in RDL layer are studied.The microstrip line requires a lower number of TSVs,but the work frequency band is narrower.Coplanar waveguide has lower dispersion and the design is more flexible,and the ground can reduce the interference from transmission line in the same layer.In coplanar strip line structure,the smaller the gap or the wider the line,the smaller the loss.But this structure requires a higher process precision.The loss of coplanar stripe line is large and the working frequency band is narrow,makes the structure is only suitable for the 3D IC with ground near the medium layer.The electrical characteristics of discontinuous structures in TSV based 3D ICs are introduced,which contains transmission line with jump width,jump radius structure near TSV and right angle bending structure.3.The electrical characteristics of the TSV matrix are analyzed,including the capacitance,inductance and the loss of single signal TSV surrounded by different arrangement of ground TSVs.Due to the different electric field distribution of the signal TSV in different arrangement,the total capacitance is not superposed according to the traditional capacitance formula according to the quantity of the ground TSV.The non-uniform distribution of electric field was verified by HFSS,and the nonlinear relationship in capacitance and the approximate linear relationship in inductance(error less than 1%)are verified by Q3 D.4.The coupling of multi-fields in TSV based 3D ICs is analyzed,in which the thermal coupling and the thermal stress generated by thermal load is obvious.The heat generated by electricity mainly comes from Joule heat,mismatch loss and dielectric loss.Joule heat is mainly related to the chain resistance and the input signal,mismatch loss in high frequency can be analyzed according to the RLCG model and impedance model.And the dielectric loss is determined by the tangent of the dielectric loss of material and the input signal.The heat generated by the electricity and the heat transferred from the active area lead to unbalanced temperature distribution in TSV chain,and a higher temperature and stress concentration are often caused at corners.5.The influence of insulation layer and signal transmission line on the multi-fields is analyzed.The coplanar stripline has unique advantages in multi-fields analysis,the electrical properties allow a flexible design on physical dimension.Finally,the influence of microfluidic cooling technology on the electric field is analyzed.When the microfluidic size is designed reasonably,part of capacitance can be compensated and the loss can be reduced.