高漏压低栅压条件下N型MOSFET热载流子注入效应研究

Investigations of Hot Carrier Injection on NMOSFET with High Vds and Low Vgs Stress

本文研究了N型MOSFET在高漏压低栅压条件下的热载流子注入效应。在3.3V N型MOSFET的漏端和栅极上分别加上5.5V和0.65V电压,发现在电应力条件下的漏端电流Id随着施加应力的时间增加而增大。导致这个现象的主要机制是漏端附近氧化层中产生了带正电荷的缺陷。另外还发现,在栅极施加反方向电压,漏端电流Id并不能发生恢复。但是125℃烘烤8小时后,漏端电流Id会发生恢复,表明空穴在加热时得到足够的能量而从缺陷陷阱中跃迁出来。此外,本文在通过研究工艺改进来提升HCI的性能中,发现在合适的氮化硅退火温度和轻掺杂漏区(Lightly Doped Drain,LDD)掺杂浓度能有效的降低NMOSFET空穴注入。

Hot carrier injection of NMOSFET under high Vds and low Vgs Stress was investigated in this paper. We found that the drain current （ Id@Vgs=0.65V, Vds=5.SV ） increased versus time with stress condition of Vgs=0.65V, Vds=5.SV. The dominant mechanism for this phenomenon is that the positively-charged traps generated in the gate oxide near the drain region. The drain current wasn＇ t recovered by forcing a negative bias on the gate; however, it can be recovered after 8 hours baking at 125℃. This indicates that the holes were released from taps after the baking. The process improvement shows that the holes injection of NMOSFET can be reduced by the proper annealing temperature of SIN and LDD dosage process.