Study On Electro-Thermo-Mechanical Characteristics Of Semiconductor Devices And Integrated Circuits (ICs) By Multiphysics Simulation

According to International Technology Roadmap for Semiconductors(ITRS)-2009: modeling and simulation, with the feature size of COMS process reaching22nm (even smaller) and the diversity of function, the issue of heat dissipation has become the bottleneck of realizing promising performance for2D and3D ICs. Therefore, to promise the reliability and performance of ICs and prevent thermal breakdown, effective thermal management should be conducted. It is also necessary to do thermo-mechnical modeling of thermal through silicon via (TTSV) and thin stack die (including adhesive and interposer) and the impact on active devices and interconnect. While the integration of CMOS process manufacturing technology is raised and dielectrical layer thinned, the corresponding capability to withstand high-voltage pulse is reduced. Electrostatic Discharge (ESD) issue is becoming the most important reliability problem in ICs. Thus, it is urgent to develop a highly effeciency and-effective algorithm and do experiments on electro-thermo-mechnical multiphysics issues, in order to analysis thermal lapse, thermo-mechanical reliability and electromagnectic pulse breakdown metioned above.This dissertation is based on the knowledge of semiconductor physics, circuit theory, electrical field, thermal transfer and mechanics, combing experiments and numerical calculation. It comprehensively investigated the electro-thermo-mechanical multiphysics coupling issues in the application of relevant semiconductor devices and ICs.Firstly, using the developed Time Domain Finite Element Method (TD-FEM), the dissertation will bring out a revised electro-thermo-mechanical coupling algorithm from the coupling mechanism between electrical, temperature and stress field. This algorithm can solve the multi-physics responses fast and accurately, considering the temperature-dependences of material parameters. These parameters include electrical conductivity, thermal conductivity, Young’s modulus, and Coefficient of Thermal Expansion (CTE). This dissertation systematically studies the thermo-mechanical responses of single-and multi-layer TTSVs, and TTSV arrays. The factors affecting multi-physics responses are analyzed in detail, including the magnitude of ESDs, liner materials and its geometry parameters. The issues of geometrical size of Fin structure, optimization of the location of hotspots and the alignment of hotspots are discussed. The temperature dependent results of hotspot alignment and different liner materials are also provided.Secondly, the experimental and simulation studies on static multiphysics responses of GaAs HBT PA and transient responses of thin film resistor are provided. The first experiment is about the impact of PVT(Power vasus Time) issue on GaAs HBT (Heterojunction Bipolar Transistor) PA in DCS/GSM handsets. Utilizing the layout of GSM-900and DCS-1800GMSK, TD-FEM simulation is conducted and verified with thermal image by thermal scan. The second experiment is regarding the impact of ESD issue on GaAs HBT PA in DCS/GSM handsets. Electro-thermal coupling analysis of thin film resistor under different ESD pulses is conducted by TD-FEM algorithm, which verified the experimental results.At last, we have proposed the scheme of an all-carbon thermal management structure for high density3-D ICs and HEMT (High Electron Mobility Transistor). It consists of GR (Graphene) heat spreaders and CNT (Carbon Nano-tube)-built TTSVs in the horizontal and vertical directions, respectively. With its implementation, the heat of hot spots can be removed to bottom heat sink and the temperature can be suppressed dramatically. Therefore, we would like to say that all-carbon structure has great potential for effective thermal management of next-generation3-D ICs. And the graphene heat spreader can also be utilized in heat dissipation of active devices such as HEMT.