A multi-deposition multi-annealing technique （MDMA） is introduced into the process of high-k/metal gate MOSFET for the gate last process to effectively reduce the gate leakage and improve the device＇s performance. ...A multi-deposition multi-annealing technique （MDMA） is introduced into the process of high-k/metal gate MOSFET for the gate last process to effectively reduce the gate leakage and improve the device＇s performance. In this paper, we systematically investigate the electrical parameters and the time-dependent dielectric breakdown （TDDB） characteristics of positive channel metal oxide semiconductor （PMOS） under different MDMA process conditions, including the depo- sition/annealing （D＆A） cycles, the D＆A time, and the total annealing time. The results show that the increases of the number of D＆A cycles （from 1 to 2） and D＆A time （from 15 s to 30 s） can contribute to the results that the gate leakage current decreases by about one order of magnitude and that the time to fail （TTF） at 63.2% increases by about several times. However, too many D＆A cycles （such as 4 cycles） make the equivalent oxide thickness （EOT） increase by about 1A and the TTF of PMOS worsen. Moreover, different D＆A times and numbers of D＆A cycles induce different breakdown mechanisms.展开更多
For many years, a Lorentz factor of L = 1/3 has been used to describe the local electric field in thin amorphous dielectrics. However, the exact meaning of thin has been unclear. The local electric field E<sub>l...For many years, a Lorentz factor of L = 1/3 has been used to describe the local electric field in thin amorphous dielectrics. However, the exact meaning of thin has been unclear. The local electric field E<sub>loc</sub> modeling presented in this work indicates that L = 1/3 is indeed valid for very thin solid dielectrics (t<sub>diel</sub> ≤ 20 monolayers) but significant deviations from L = 1/3 start to occur for thicker dielectrics. For example, L ≈ 2/3 for dielectric thicknesses of t<sub>diel</sub> = 50 monolayers and increases to L ≈ 1 for dielectric thicknesses t<sub>diel</sub> > 200 monolayers. The increase in L with t<sub>diel</sub> means that the local electric fields are significantly higher in thicker dielectrics and explains why the breakdown strength E<sub>bd</sub> of solid polar dielectrics generally reduces with dielectric thickness t<sub>diel</sub>. For example, E<sub>bd</sub> for SiO<sub>2</sub> reduces from approximately E<sub>bd</sub> ≈ 25 MV/cm at t<sub>diel</sub> = 2 nm to E<sub>bd</sub> ≈ 10 MV/cm at t<sub>diel</sub> = 50 nm. However, while E<sub>bd</sub> for SiO<sub>2</sub> reduces with t<sub>diel</sub>, all SiO<sub>2</sub> thicknesses are found to breakdown at approximately the same local electric field (E<sub>loc</sub>)<sub>bd</sub> ≈ 40 MV/cm. This corresponds to a coordination bond strength of 2.7 eV for the silicon-ion to transition from four-fold to three-fold coordination in the tetrahedral structure.展开更多
利用等效1 MeV中子和γ射线对1200 V SiC功率MOSFET进行辐射,研究了电离损伤和位移损伤对器件的影响,并分析了辐射后器件栅氧长期可靠性。结果表明:中子辐射后器件导通电阻发生明显退化,与辐射引入近界面缺陷降低载流子寿命和载流子迁...利用等效1 MeV中子和γ射线对1200 V SiC功率MOSFET进行辐射,研究了电离损伤和位移损伤对器件的影响,并分析了辐射后器件栅氧长期可靠性。结果表明:中子辐射后器件导通电阻发生明显退化,与辐射引入近界面缺陷降低载流子寿命和载流子迁移率有关。时间依赖的介质击穿(TDDB)结果表明,栅泄漏电流呈现先增加后降低趋势,与空穴捕获和电子捕获效应有关。中子辐射后栅漏电演化形式未改变,但氧化层击穿时间增加,这是中子辐射缺陷增加了Fowler-Nordheim(FN)隧穿势垒的缘故。总剂量辐射在器件氧化层内引入陷阱电荷,使得器件阈值电压负向漂移。随后的TDDB测试表明,与中子辐射一致,总剂量辐射未改变栅漏电演化形式,但氧化层击穿时间提前。这是总剂量辐射在氧化层内引入额外空穴陷阱和中性电子陷阱的缘故。展开更多
SiC MOS器件氧化膜可靠性是SiC器件研究中的重要方面。本文对4H-SiC MOS结构进行电子回旋共振(ECR)氮等离子体氧化后退火工艺处理,采用阶跃电流经时击穿以及XPS分析的方法对其氧化膜稳定性进行了电学以及物理性质方面上的分析。经分析...SiC MOS器件氧化膜可靠性是SiC器件研究中的重要方面。本文对4H-SiC MOS结构进行电子回旋共振(ECR)氮等离子体氧化后退火工艺处理,采用阶跃电流经时击穿以及XPS分析的方法对其氧化膜稳定性进行了电学以及物理性质方面上的分析。经分析氮等离子体处理8min的样品击穿时间和单位面积击穿电荷量都有了明显提高,并且早期失效比率有了明显降低。实验结果表明,经过适当时间的处理,ECR氮等离子体氧化后退火工艺可以有效地降低界面缺陷的密度,提高界面处激活能,从而提高绝缘膜耐受电流应力的能力。展开更多
The saturation behavior of stress current is studied.The three types of precursor sites for trap generation are also introduced by fitting method based on first order rate equation.A further investigation by statistic...The saturation behavior of stress current is studied.The three types of precursor sites for trap generation are also introduced by fitting method based on first order rate equation.A further investigation by statistics experiments shows that there are definite relationships among time constant of trap generation,the time to breakdown,and stress voltage.It also means that the time constant of trap generation can be used to predict oxide lifetime.This method is faster for TDDB study compared with usual breakdown experiments.展开更多
基金supported by the National High Technology Research and Development Program of China(Grant No.SS2015AA010601)the National Natural Science Foundation of China(Grant Nos.61176091 and 61306129)
文摘A multi-deposition multi-annealing technique （MDMA） is introduced into the process of high-k/metal gate MOSFET for the gate last process to effectively reduce the gate leakage and improve the device＇s performance. In this paper, we systematically investigate the electrical parameters and the time-dependent dielectric breakdown （TDDB） characteristics of positive channel metal oxide semiconductor （PMOS） under different MDMA process conditions, including the depo- sition/annealing （D＆A） cycles, the D＆A time, and the total annealing time. The results show that the increases of the number of D＆A cycles （from 1 to 2） and D＆A time （from 15 s to 30 s） can contribute to the results that the gate leakage current decreases by about one order of magnitude and that the time to fail （TTF） at 63.2% increases by about several times. However, too many D＆A cycles （such as 4 cycles） make the equivalent oxide thickness （EOT） increase by about 1A and the TTF of PMOS worsen. Moreover, different D＆A times and numbers of D＆A cycles induce different breakdown mechanisms.
文摘For many years, a Lorentz factor of L = 1/3 has been used to describe the local electric field in thin amorphous dielectrics. However, the exact meaning of thin has been unclear. The local electric field E<sub>loc</sub> modeling presented in this work indicates that L = 1/3 is indeed valid for very thin solid dielectrics (t<sub>diel</sub> ≤ 20 monolayers) but significant deviations from L = 1/3 start to occur for thicker dielectrics. For example, L ≈ 2/3 for dielectric thicknesses of t<sub>diel</sub> = 50 monolayers and increases to L ≈ 1 for dielectric thicknesses t<sub>diel</sub> > 200 monolayers. The increase in L with t<sub>diel</sub> means that the local electric fields are significantly higher in thicker dielectrics and explains why the breakdown strength E<sub>bd</sub> of solid polar dielectrics generally reduces with dielectric thickness t<sub>diel</sub>. For example, E<sub>bd</sub> for SiO<sub>2</sub> reduces from approximately E<sub>bd</sub> ≈ 25 MV/cm at t<sub>diel</sub> = 2 nm to E<sub>bd</sub> ≈ 10 MV/cm at t<sub>diel</sub> = 50 nm. However, while E<sub>bd</sub> for SiO<sub>2</sub> reduces with t<sub>diel</sub>, all SiO<sub>2</sub> thicknesses are found to breakdown at approximately the same local electric field (E<sub>loc</sub>)<sub>bd</sub> ≈ 40 MV/cm. This corresponds to a coordination bond strength of 2.7 eV for the silicon-ion to transition from four-fold to three-fold coordination in the tetrahedral structure.
文摘利用等效1 MeV中子和γ射线对1200 V SiC功率MOSFET进行辐射,研究了电离损伤和位移损伤对器件的影响,并分析了辐射后器件栅氧长期可靠性。结果表明:中子辐射后器件导通电阻发生明显退化,与辐射引入近界面缺陷降低载流子寿命和载流子迁移率有关。时间依赖的介质击穿(TDDB)结果表明,栅泄漏电流呈现先增加后降低趋势,与空穴捕获和电子捕获效应有关。中子辐射后栅漏电演化形式未改变,但氧化层击穿时间增加,这是中子辐射缺陷增加了Fowler-Nordheim(FN)隧穿势垒的缘故。总剂量辐射在器件氧化层内引入陷阱电荷,使得器件阈值电压负向漂移。随后的TDDB测试表明,与中子辐射一致,总剂量辐射未改变栅漏电演化形式,但氧化层击穿时间提前。这是总剂量辐射在氧化层内引入额外空穴陷阱和中性电子陷阱的缘故。
文摘The saturation behavior of stress current is studied.The three types of precursor sites for trap generation are also introduced by fitting method based on first order rate equation.A further investigation by statistics experiments shows that there are definite relationships among time constant of trap generation,the time to breakdown,and stress voltage.It also means that the time constant of trap generation can be used to predict oxide lifetime.This method is faster for TDDB study compared with usual breakdown experiments.
基金The Special funds for Major State Basic Research Projects under Grant G2000036504,andin part by National High Technology Research and Development Program of China under Grant2003AA1Z1370
