一种具有子沟槽结构的屏蔽栅MOSFET的研究  

A shielded gate trench MOSFET with sub-trench structures

作　　者：朱晨凯 赵琳娜 顾晓峰 周锦程 杨卓 ZHU Chenkai;ZHAO Linna;GU Xiaofeng;ZHOU Jincheng;YANG Zhuo(Engineering Research Center of IoT Technology Applications(Ministry of Education),Department of Electronic Engineering,Jiangnan University,Wuxi 214122,Jiangsu Province,China;Wuxi NCE Power Co.,Ltd.,Wuxi 214122,Jiangsu Province,China)

机构地区：[1]江南大学电子工程系物联网技术应用教育部工程研究中心,江苏无锡214122 [2]无锡新洁能股份有限公司,江苏无锡214122

出　　处：《电子元件与材料》2022年第6期621-626,共6页Electronic Components And Materials

基　　金：国家自然科学基金(61504049);江苏省研究生科研与实践创新计划项目(KYCX18_1855);中央高校基本科研业务费专项资金(JUSRP51510)。

摘　　要：为了降低屏蔽栅沟槽型(SGT,Shield Gate Trench)MOSFET的导通电阻、提高器件的品质因数,通常使用增加屏蔽栅沟槽深度和密度的方法,但是在刻蚀高密度深沟槽时会使晶圆产生严重的翘曲现象。因此,提出一种100 V具有子沟槽(ST,Sub-Trench)的SGT(ST-SGT)器件结构。在相邻的主沟槽间插入子沟槽后,显著降低了器件栅极附近的电场峰值,避免栅氧化层出现过早击穿,同时较浅的子沟槽提升了外延层纵向电场分布的均匀性,改善了高密度深沟槽带来的晶圆翘曲问题。通过使用Sentaurus TCAD仿真软件,调节子沟槽深度和上层外延层电阻率两个重要参数,对ST-SGT进行优化设计。结果表明,当子沟槽深度为2.5μm、上层外延电阻率为0.23Ω·cm时,对应的ST-SGT的品质因数(FOM,Figure of Merit)最大,此时击穿电压为135.8 V,特征导通电阻为41.4 mΩ·mm^(2)。优化后的ST-SGT与传统SGT相比,其FOM提高了19.6%。To reduce its on-resistance and improve its figure-of-merit(FOM),methods of increasing the depth and density of the shielding gate trenches are often adopted for the shield gate trench metal oxide semiconductor field effect transistor(SGT-MOSFET).However,etching of high-density and deep trenches would cause serious warpage of the wafer.Here we proposed a 100 V SGT-MOSFET with sub-trench(ST-SGT).Due to the insertion of sub-trenches between adjacent main-trenches,peak value of the electric field near the gate is significantly reduced,as well as the risk of premature breakdown of the gate oxide.The shallower sub-trenches improve the uniformity of the vertical electric field distribution in the epitaxial layer and avoid the serious wafer warpage.Sentaurus TCAD was used to optimize the ST-SGT by modulating the depth of the sub-trench and resistivity of the upper epitaxial layer.Simulation result shows that a sub-trench depth of 2.5μm and an upper epitaxial resistivity of 0.23Ω·cm are suitable parameters for the ST-SGT,and the corresponding FOM reaches its maximum value.The optimized ST-SGT obtains a breakdown voltage of 135.8 V and a specific on-resistance of 41.4 mΩ·mm^(2).Compared with the conventional SGT(C-SGT),the FOM of optimized ST-SGT is improved by 19.6%.

关 键 词：屏蔽栅沟槽型MOSFET 电荷平衡 击穿电压 特征导通电阻 品质因数 

分 类 号：TN386[电子电信—物理电子学]