Electro-thermal Analysis Of System In Package

With semiconductor technologies unceasingly advancing, the power density of integrated circuits (IC) increases, resulting in junction temperature rising simultaneously. Therefore, thermal requirement becomes one of the obstacles that prevent the progress of integration. On the other hand, the rising temperature could influence the electrical characteristics of the devices within the die and the robustness and reliability of the entire package system. System in package (SiP), as one of the promising options of future IC, has to be comprehensively considered from electrical and thermal perspectives due to its great complexities of system design, circuit function, signal feature, and technology implementation. The thesis mainly focuses on the electrical and thermal effects of SiP and analyzes the electrical characteristics of the active device, thermal characteristics of the whole package and the electro-thermal effect of global interconnects.Firstly, the background and current status of studies on electro-thermal analysis of SiP are presented. Since SiP covers a wide range from tiny transistors to large chips and research results at home and abroad are just focused on certain parts, this thesis studies the electrical and thermal characteristics of SiP from the following four aspects. 1) When the physical dimensions of a transistor in ICs shrink down to nanometer, its performance affected by temperature variation is a rather complicated case. Hence, this work based on the temperature models in BSIM3 presents the temperature dependence of device behavior and the analytical model for temperature-insensitive operation points in both linear and saturation regions and the optimum supply voltage for advanced technologies. 2) Subthreshold voltage decreases with technologies, which causes growing percentage of leakage power and moreover leakage current inducing leakage power exponentially increases with temperature. So a simple and accurate semi-physical leakage current model for MOSFET in advanced nano technologies is proposed based on least squares method. 3) According to thermal-electrical analogies, equivalent thermal-circuit method is proposed to estimate junction temperature, i.e. chip temperature. Applying this method to a real and typical package and retrieving equivalent thermal resistance network, we obtain a fast and accurate formula for junction temperature in steady state. 4) In advanced technologies, interconnect is longer and its resistivity is larger than before so interconnect problems arouse scholars'interests. This thesis presents modeling and analysis of electro-thermal effects on the temperature profile of global interconnects. Based on the electro-thermal model, an iterative method is proposed for accurate analysis of interconnect temperature profile.Although these above works are just parts of electro-thermal analysis of SiP, they are of great practical significances. The proposed analytical models for temperature-insensitive operation points and the optimum supply voltage provide beneficial instructions to design reliable high-performance devices in advanced technologies; the semi-physical leakage current model is useful for fast leakage power estimation, electro-thermal analysis and high-level IC design; the junction temperature predicted by the thermal circuit is useful for package analysis, design and optimization; the electro-thermal study of global interconnect reveals the necessity of incorporating electro-thermal coupling effects in thermal analysis of global interconnects.