漏源电压对SiC MOSFET阈值电压准确测量影响的研究  

Research on Influence of Drain-source Voltage on Accurate Measurement of SiC MOSFET Threshold Voltage

作　　者：姚博均 郭春生[1] 崔绍雄 李嘉芃 张亚民[1] YAO Bojun;GUO Chunsheng;CUI Shaoxiong;LI Jiapeng;ZHANG Yamin(School of Microelectronics,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学微电子学院,北京100124

出　　处：《电源学报》2024年第3期258-263,共6页Journal of Power Supply

摘　　要：相较于Si器件,SiC MOSFET近界面氧化物陷阱区域更广,界面态陷阱密度高出2个数量级,大量陷阱不断俘获或释放电荷,导致阈值电压(Vth)随时间波动较大,因而Vth的准确重复测量成为难题。标准中阈值电压测量采用预处理的方法,保证每次测量时陷阱电荷状态的一致性,但标准中未考虑漏源电压影响预处理填充后的陷阱状态,导致阈值电压测试误差。针对该问题,首先通过测量不同漏源电压脉冲影响下的转移曲线,显示不同源漏电压对阈值电压的影响;然后,基于瞬态电流法分析了漏源电压对陷阱电荷状态的影响;进而,分析了漏源电压影响陷阱的机理;最后对比了不同漏源电压对阈值电压测量的影响。实验表明,漏源电压影响栅漏间电场正负,进而影响陷阱填充或释放电荷,导致阈值电压漂移。测量阈值电压时使用较小漏源电压可提高测量准确性,减小可靠性实验由测试因素造成的误差。Compared with that in a Si device,the area of near interface oxide traps in a SiC MOSFET is wider,and the corresponding density of traps is two orders of magnitude higher.A lot of traps which are continuously capturing or releasing charges will cause the threshold voltage(Vth)to fluctuate with time,leading to the difficulty in accurately and repeatedly measuring the value of Vth.In the standard method,the value of Vth is measured using a preprocessing method to ensure the consistence in measuring the trap charge state in each time.However,the preprocessed trap state which is affected by drain-source voltages is not taken into account in the standard method,which will bring errors to the Vth test.Aimed at this problem,the transfer curves under the influences of different drain-source voltage pulses were measured at first,which show the effects of different drain-source voltages on Vth.Second,the influence of drain-source voltage on the trap charge state was analyzed based on the transient current method,thus clarifying the mechanism of the influence of drain-source voltage on traps.Finally,the influences of different drain-source voltages on Vth measurement were compared.Results indicate that the drain-source voltage affects the positive and negative electric field between the gate and drain,thereby affecting the trap charge state and causing the Vth drift.It is suggested that a smaller drain-source voltage should be used when measuring Vth to improve the measurement accuracy and reduce errors caused by testing factors in reliability experiments.

关 键 词：阈值电压 重复性 碳化硅MOSFET 栅极结构 

分 类 号：TN306[电子电信—物理电子学]