阻抗分析仪测量功率MOSFET器件栅极分离电容C-V特性的误差分析及调控方法  

Error Analysis and Regulation Method of Impedance Analyzer in Measuring Split C-V Characteristics of Power MOSFET Device

作　　者：蔡雨萌 赵志斌 徐子珂 孙鹏 李学宝 Cai Yumeng;Zhao Zhibin;Xu Zike;Sun Peng;Li Xuebao(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University,Beijing,102206,China)

机构地区：[1]新能源电力系统国家重点实验室(华北电力大学),北京102206

出　　处：《电工技术学报》2022年第12期3016-3027,3037,共13页Transactions of China Electrotechnical Society

基　　金：国家重点研发计划资助项目(2018YFB0905703)。

摘　　要：功率MOSFET器件栅极分离电容C-V特性(C_(GS)-V_(G)、C_(GD)-V_(G))的准确测量对于器件的建模及栅氧可靠性的评估十分重要。阻抗分析仪是测量C_(GS)-V_(G)、C_(GD)-V_(G)的关键设备。在利用阻抗分析仪测量三端器件的某个参数时,需对非测量的第三端进行屏蔽以消除其引入的并联阻抗误差。而功率MOSFET器件在栅压超过阈值电压时呈导通态,影响测量电路拓扑,进而引入其他测量误差。该文针对阻抗分析仪测量功率MOSFET器件的C_(GS)-V_(G)、C_(GD)-V_(G)进行详细的误差分析,揭示测量误差产生的原因;建立测量的等效电路,给出测量误差的解析表达式;结合实验和数值分析量化误差分析,验证了等效电路模型的有效性;最后,提出三种可实现C-V特性准确测量的调控方法并予以实验验证。结果表明,测量误差发生在器件导通后,此时器件漏源极间由电容态转变为低阻态,屏蔽端的寄生电感(L_(5))与自动平衡电桥的等效输入阻抗(L_(3))分流,引入误差。当L_(3)和L_(5)满足一定的匹配关系时,可实现不同频率下的准确测量。The accurate measurement of the split C-V characteristics(C_(GS)-V_(G)and C_(GD)-V_(G))of power MOSFET devices is very important for device modeling and gate oxide reliability evaluation.Impedance analyzer is the key equipment to measure the C_(GS)-V_(G)and C_(GD)-V_(G).When using the impedance analyzer to measure a parameter of a three-terminal device,it is necessary to shield the non-measured third terminal to eliminate the introduced parallel impedance error.However,the power MOSFET device turns on when the gate voltage exceeds the threshold voltage,which affects the measurement circuit topology and introduces other measurement errors.In this paper,a detailed error analysis of the C_(GS)-V_(G)and C_(GD)-V_(G)measured by the impedance analyzer was carried out,and the reason of measurement error was revealed.The equivalent circuit model of the measurement was established,and the analytical expression of the measurement error was given.The error analysis was quantified and the effectiveness of the equivalent circuit model was verified by combining experiment and numerical analysis.Finally,three control methods that can achieve accurate measurement of C-V characteristics were proposed and verified by experiments.The results show that the measurement error occurs after the device turns on.The drain and source of the device transition from capacitance to low resistance.The parasitic inductance of the guarding(L_(5))is shunted from the equivalent input impedance of the automatic balance bridge(L_(3)),which introduces errors.An accurate measurement under different frequencies can be achieved when L_(3) and L_(5)satisfya certain matching relationship.

关 键 词：功率 MOSFET 器件 阻抗分析仪 栅极分离电容 C-V 特性 等效电路模型 误差分析 

分 类 号：TN386[电子电信—物理电子学]