The Impact of Repetitive Unclamped Inductive Switching on the Electrical Parameters of Low-Voltage Trench Power nMOSFETs
The Impact of Repetitive Unclamped Inductive Switching on the Electrical Parameters of Low-Voltage Trench Power nMOSFETs
复制标题
DOI：
10.1109/ted.2010.2049062
复制
发表时间：
2010-05
影响因子：
3.1
通讯作者：
O. Alatise;I. Kennedy;G. Petkos;K. Heppenstall;K. Khan;Jim Parkin;A. Koh;P. Rutter
中科院分区：
文献类型：
--
作者：
O. Alatise;I. Kennedy;G. Petkos;K. Heppenstall;K. Khan;Jim Parkin;A. Koh;P. Rutter
研究了重复非钳位电感开关（UIS）引起的热载子注入（HCI）对低压沟槽功率n型mosfet （nmosfet）电性能的影响。在to -220封装中，已制造出额定击穿电压为20和30 v的沟槽功率nmosfet，并在150°C的安装基温TMB下，以不同的雪崩电流IAV进行了超过1亿次重复UIS。雪崩传导过程中通道内的冲击电离导致栅极介电介质注入热孔，导致阈值电压VGSTX随着雪崩循环次数N的增加而降低。实验数据表明，阈值电压ΔVGSTX与n的变化呈幂律关系，幂律前因子与雪崩电流成正比。1亿次循环后，在20 v额定mosfet中观察到，当IAV从160 A增加到225 A时，幂律前因子增加了30%，近似线性关系。具有雪崩循环的稳定亚阈值斜坡表明界面陷阱的产生可能不是一种主动的退化机制。通过测试2.5 m和4 m单元间距30v额定mosfet，还研究了单元间距对雪崩坚固性的影响。测量表明，当单元间距降低37.5%时，幂律预因子降低了40%。更小的单元间距mosfet提高了VGSTX的稳定性，这是由于每个单元的雪崩电流更低，导致更少的热孔注入，因此VGSTX位移更小。与4米细胞间距mosfet相比，2.5米细胞间距mosfet的状态电阻RDSON提高了25%，RDSON稳定性更好，亚阈值斜率降低了20%，但初始IDSS提高了100%，雪崩循环时IDSS稳定性降低。这些结果对于汽车MOSFET的制造商来说非常重要，因为在MOSFET的使用寿命期间预计会发生多次雪崩。
The impact of hot-carrier injection (HCI) due to repetitive unclamped inductive switching (UIS) on the electrical performance of low-voltage trench power n-type MOSFETs (nMOSFETs) is assessed. Trench power nMOSFETs with 20- and 30-V breakdown voltage ratings in TO-220 packages have been fabricated and subjected to over 100 million cycles of repetitive UIS with different avalanche currents IAV at a mounting base temperature TMB of 150°C. Impact ionization during avalanche conduction in the channel causes hot-hole injection into the gate dielectric, which results in a reduction of the threshold voltage VGSTX, as the number of avalanche cycles N increases. The experimental data reveal a power-law relationship between the change in the threshold voltage ΔVGSTX and N. The results show that the power-law prefactor is directly proportional to the avalanche current. After 100 million cycles, it was observed in the 20-V rated MOSFETs that the power-law prefactor increased by 30% when IAV was increased from 160 to 225 A, thereby approximating a linear relationship. A stable subthreshold slope with avalanche cycling indicates that interface trap generation may not be an active degradation mechanism. The impact of the cell pitch on avalanche ruggedness is also investigated by testing 2.5- and 4- m cell-pitch 30-V rated MOSFETs. Measurements showed that the power-law prefactor reduced by 40% when the cell pitch was reduced by 37.5%. The improved VGSTX stability with the smaller cell-pitch MOSFETs is attributed to a lower avalanche current per unit cell resulting in less hot-hole injection and, hence, smaller VGSTX shift. The 2.5-m cell-pitch MOSFETs also show 25% improved on -state resistance RDSON, better RDSON stability, and 20% less subthreshold slope compared with the 4-m cell-pitch MOSFETs, although with 100% higher initial IDSS and less IDSS stability with avalanche cycling. These results are important for manufacturers of automotive MOSFETs where multiple avalanche occurrences over the lifetime of the MOSFET are expected.