Analysis And Modeling Of SiGe HBT Thermal Resistance

SiGe HBT plays an important role in integrated circuits with its advantages of high gain,high frequency,low phase noise,excellent low temperature characteristics,and high emitter efficiency.Thermal resistance is one of the important indicators for testing the performance of semiconductor devices,so thermal resistance is a very important part in the research process of SiGe HBT devices.In order to shorten the R & D(research and development)duration and cut the cost,replacing device with model to extract parameters is an effective way.This thesis focuses on the thermal resistance analysis and parameter extraction of SiGe HBT.Firstly,the current output curve of SiGe HBT is obtained by TCAD simulation software.Then the thermal resistance is calculated by classical extraction method,and the influence of device size on it is discussed.Finally,this thesis improves the method to estimate the thermal resistance for HBT with trench isolation,and puts forward a simple algorithm to calculate the metal layer thermal resistance.The content of this thesis includes:1)The model of HBT is built and embedded in TCAD simulation software.2)The thermal resistance values of SiGe HBT devices are calculated by three classical thermal resistance extraction algorithms.3)Based on TCAD simulation results,the effects of emitter width,emitter length,emitter area,distance between emitter and base on thermal resistance are studied.4)An improved method for calculating the thermal resistance of trench-isolated SiGe HBTs is proposed which is very simple and does not need any iteration to calculate metal layer thermal resistance.The thermal resistance is tested against iterative and analytic methods reported before.Good agreement is obtained between simulated and measured results for SiGe HBTs.