高压单边器件的衬底电流再次升高和相关的热载流子注入效应  

Substrate Current and Hot-Carrier-Injection in High Voltage Asymmetrical n-Channel MOS Transistor Technology

作　　者：戴明志[1] 刘韶华 程波 李虹 叶景良 王俊[1] 江柳 廖宽仰 

机构地区：[1]中国科学院上海微系统与信息技术研究所 [2]上海宏力半导体制造有限公司,上海201203

出　　处：《Journal of Semiconductors》2008年第4期757-764,共8页半导体学报（英文版）

摘　　要：基于泊松方程和幸运电子模型,推出了适用于高压n型器件衬底电流(ISUB)的公式,并且为模拟和实验测量的结果所验证.普通n型低压器件的热载流子注入(HCI)效应和ISUB相关.因此,ISUB特征曲线的解释理论和基于理论的正确公式表述对于确保器件设计的可靠性尤为重要.高压器件的ISUB随栅极电压变化在峰值后再次升高.然而在普通低压器件的经典特征曲线中,ISUB仅呈现一个峰.高压器件的ISUB再次升高及其相关的可靠性问题成为新的研究热点.最广为接受的理论(Kirk effect)认为,ISUB再次升高是因为栅控沟道内的经典强电场区移动到沟道外n+漏极的边缘.本文与之不同,认为高压器件ISUB的再次升高并非因为经典强电场区的移动,而是因为在n+漏极边缘出现独立的强电场区,和经典强电场区同时并存,这就是双强电场模型.该双强电场模型仅有经典强电场的ISUB方程不适用于高压器件,新的ISUB方程也由此双强电场模型推导出来,公式与实验结果吻合.进一步地,双强电场模型引进了空穴在氧化层的陷落机制,解释了高压器件的热载流子注入效应.The incorporation of high voltage transistors into the advanced VLSI chips has been limited by the reliability of the manufactured integrated circuits. As a monitor of hot-carrier-injection reliability, the substrate current （ISUB） usually increases in high voltage transistors, but has only one peak in standard low voltage transistors. Correspondingly, the mechanisms of the hot-carrier-injection effect in high voltage N-channel transistors should also be investigated. Based on the Poisson＇s equation,and simulation and experimental results,a second impact ionization region is responsible for the second increase of ISUB. An explanation for the appearance of this second impact ionization region that differs from the prevalent theory, the Kirk-effect, is proposed. The Kirk-effect predicts that the typical high-electric field region widens from the gate edge to the n^＋ drain edge. However, two separate high-electricfield regions with fixed locations coexist instead. The second high-field region is not the expansion of the conventional region. An improved equation for ISUB is proposed according to the two-high-field-region model. This two-high-field-region model is also consistent with the phenomena observed under the various HCI stress conditions with and without back bias. Back bias reduces the supplied voltage for high-voltage transistors by half without degrading their performance and reliability.

关 键 词：衬底电流 双强电场模型 衬底电流公式 热载流子注入 

分 类 号：TN43[电子电信—微电子学与固体电子学]