中压沟槽MOSFET的设计与研究

Design and research of medium voltage trench MOSFET

基于仿真和实验方法,开展了100VN沟槽MOSFET的设计研究工作.通过沟槽深度,体区注入剂量和栅氧化层厚度拉偏,获得了对击穿电压,阈值电压和导通电阻的影响规律并对机理进行了分析,仿真工具同时描述了器件内部的电流路径和碰撞电离率分布.随着沟槽深度增加击穿电压先升后降,导通电阻则表现为相反趋势;击穿电压与注入剂量具有弱相关性,阈值电压随注入剂量增加而升高;击穿电压随着栅氧化层厚度增加整体表现上升趋势,但变化幅度不大,阈值电压与厚度变化表现出强相关性.通过逐步优化获得了最终结构和工艺参数为沟槽深度1.5 um,体区注入剂量1.3E13,栅氧化层厚度700 A,通过流片获得器件最终电性参数为击穿电压为105.6 V,阈值电压2.67 V,导通电阻3.12 mR,相较于仿真参数分别有98%,94%和75%的变化率.

Based on simulation and experimental methods,the design and research of 100VN trench MOSFET is carried out.Through the trench depth,body dose and gate oxide thickness experiment,the effects on breakdown voltage,threshold voltage and on-resistance are obtained and the mechanism is analyzed.The current path inside the device and the distribution of impact ionization rate can be seen through the simulation.As the trench depth increases,the breakdown voltage first increases and then decreases,and the on-resistance shows an opposite trend;the breakdown voltage has a weak correlation with the implant dose,and the threshold voltage increases with the increase of the implant dose;the breakdown voltage increases with the gate oxide thickness increases,but the change range is not large,and the threshold voltage has a strong correlation with the thickness changes.Through gradual optimization,the final structure and process parameters are obtained as trench depth is 1.5 um,body dose is 1.3E13,gate oxide thickness is 700 A and the device final electrical parameters are obtained by real tape-out.Finally,we can get the breakdown voltage is 105.6 V,threshold voltage is 2.67 V and on-resistance is 3.12 mR.Compared with the simulation results,the change rates are 98%,94%and 75%respectively.