摘要
本文报道了在氧等离子体中暴露过的热生长二氧化硅ＭＯＳ结构，置于－１７０至１００℃的环境中，经受－０．３至－１０ＭＶ／ｃｍ电场作用１ｍｓ至１００ｓ的时效处理后，仍然表现出不稳定性的实验结果．１至１０ｍｓ的时效时间是常规负偏压温度不稳定性试验时间的几百，乃至几十万分之一，用这样短的低温负偏压应力，研究了光照对ＭＯＳ结构负偏压温度不稳定性的影响，实验与预想一致，Ｎ型ＭＯＳ结构应力处理时，若无光照，时效时间短于１０ｍｓ，处理后Ｃ－Ｖ曲线不位移，若有光照，Ｃ－Ｖ曲线向左位移０．１５Ｖ左右．对于Ｐ型ＭＯＳ结构，Ｃ－Ｖ曲线总会发生位移，与光照与否无关，而且其位移大小与Ｎ型ＭＯＳ结构有光照的情形相当．另外还研究了ＭＯＳ结构带中电压位移对于负偏压温度应力中三个因素（偏置电压、时效时间和温度）的依赖关系．这些实验试图把负偏压温度不稳定现象中的空穴注入与空穴注入二氧化硅向后体内输运的过程分开．实验结果进一步证实了注入的空穴跳跃模型和空穴输运过程具有热激活的特征．
Abstract Negative bias temperature instability in both n-type and p-type MOSstructures with thermal oxides exposed in oxygen plasma were studied under variousnegative bias stress conditions at temperatures ranging from-170℃ to 100℃,inaging times ranging from lins to 100s and at application fields ranging from -0.3MV/cm to -10MV/cm.The lowest temperatures used in this work were seldom.Theaging times, lins and 10ms,were a few hundredth,and even a few ten thousandthof those times us,ed in conventional negative bias temperature instability experiments.The effect of illumination on the surface of MOS structures during stress on themidgap voltage shifts was investigated.It was found that if an n-type MOS structure is not illuminated during stress aging period of lins or 10ms,the C--V curveof the testing MOS structure does not really shift,and if illuminated,about 0.15Vmidgap voltage shift can be observed. However,for p-type MOS structure,a midgapvoltage shift allways occurs alter a similar stress to the one used in the above experiment of n-type MOS structure in spite of whether or not the p-type MOS structureis illuminated during stress.Studies were also made for the dependences of the midgap voltage shift on negative bias voltage,stress aging time and temperature. It isthe key of performing these experiments to separate the hole injection from the holetransportation to oxide bulk once holes inject into oxide hole traps in the wholeprocess of buildup oxide charge during negative bias stress.Out results further confirmed the hole hopping model of the buildup oxide charge and the hole transportation with thermal excitation characteristic.
基金
国家自然科学基金
