UMOSFET功率器件漏电失效分析及工艺改善

Leakage Failure Analysis and Process Improvement for UMOSFET Power Devices

针对U型沟槽MOSFET（UMOSFET）功率器件栅极和源极间发生漏电失效的问题,对失效器件进行了电学测试和缺陷检测,对失效现象和失效机理进行了分析,并进行了相关工艺模拟和工艺实验。采用透射电子显微镜（TEM）、扫描电子显微镜（SEM）和聚焦离子束（FIB）对失效芯片的缺陷进行分析和表征。结果表明,器件的U型沟槽底部栅氧化层存在的缺陷是产生漏电的主要原因,湿氧工艺中反应气体反式二氯乙烯（TransLC）的残留碳化造成了芯片栅氧层中的缺陷。通过工艺模拟和实验,优化了湿氧工艺条件,工艺改进后产品的成品率稳定在98%～99%,无漏电失效现象。

The electrical test and defect detection were carried out on the failure device to verify the problem of leakage failure between the gate and the source of the U-shaped trench MOSFET（ UMOSFET）power device. The failure phenomenon and failure mechanism of the UMOSFET were analyzed,and the related process simulation and the process experiment were carried out. The defects of failure chips were analyzed and characterized by transmission electron microscope（ TEM）,scanning electron microscope（ SEM） and focused ion beam（ FIB）. The results show that the defects in the gate oxide layer of the U-shaped trench bottom of the device are the main cause of the leakage,and defects in the oxide layer of the chip induced by the residual carbonization of the reaction gas trans-dichloroethylene（ TransLC） in the wet oxidation process. The conditions of wet oxidation process were optimized by process simulation and experiment. After process improvement,the product yield is remained at 98%-99%,and no leakage failure is occurred for UMOSFETs.