CAREER: Fundamental Reliability Physics of MOS Devices Based on Deuterium Isotope Effects

提出的职业发展计划是一个集成的研究和教学的努力，晶体管可靠性物理。本CAREER提案的研究部分侧重于MOS器件降解机制及其同位素效应的基础研究。MOS晶体管的退化是由于高能热电子在SiO2-Si界面处破坏Si-H（氢）键引起的。目前的理论和实验表明，硅氢键断裂是由两个相互竞争的过程引起的：由高能热电子引起的激发和由硅氢键的振动模式与硅晶格的声子模式之间的能量耦合引起的去激发。Si- d（氘）键与Si晶格（TO声子）之间的能量耦合比Si- h键与Si晶格之间的能量耦合效率高得多。因此Si-D键比Si-H键更坚固，这就是所谓的同位素效应。基于这一原理，氘处理的MOS晶体管表现出比传统氢处理更长的热载子寿命（超过50倍）。有证据表明，如果了解降解机制及其同位素效应，MOS晶体管的寿命有可能进一步提高100倍以上。两种振动模式之间的有效能量耦合的特征是它们的频率相同或非常接近。能量耦合的研究对于理解降解机理及其同位素效应具有重要意义。提出的研究计划将集中在两个方面：1)从基础角度研究深亚微米MOS晶体管的退化机制；2)研究CMOS逆变器中MOS器件的动态热载流子退化。在第一个推力中，我将使用拉曼和红外（IR）光谱来研究Si-H和Si-D键的振动模式。研究计划的最终目标是发展预测原则，从这些原则中可以设计加工，以实现MOS晶体管的最大寿命改进。在第二个推力中，我将研究晶体管在动态应力或交流应力下的氘同位素效应，因为晶体管在实际电路中是在交流条件下工作的。拟议的研究是在PI已经开展的研究工作的基础上进行的。该职业计划的教育部分寻求支持开发新的实验课程，集成电路器件制造，并在阿巴拉契亚社区（代表性不足的群体）重点开展教育推广活动。在肯塔基州通过研究挑战信托基金（RCTF）的支持下，英国正在建设一个设备制造设施。将开设一门新的实验课程，重点是集成电路器件的制造，与美国其他大学的类似课程相当。本课程是一门动手实验课程，学生有机会为集成电路构建半导体器件。本课程将于2001年秋季首次为高年级本科生和研究生开设。该课程的多学科性质将为学生提供一个独特的研究和学习环境。目标是通过综合方法进行研究和教学，在物理学、材料科学和电气工程等传统学科之间建立桥梁。教育目标的另一个组成部分涉及针对肯塔基州东部和南部包括阿巴拉契亚社区的高中生的教育推广活动。其中一个目标是通过举办一系列微电子研讨会来鼓励这些高中生追求高科技事业。另一种方法是提供一个实验项目，教他们构建一些有用的数字电路。高中学生将从已经建立的项目中招募，即由农村发展中心组织的罗杰斯学者项目，该项目已经参与。

The proposed CAREER development program is an integrated research and teaching effort in MOStransistor reliability physics. The research component of this CAREER proposal focuses on fundamental study of mechanisms for the MOS device degradation and its isotope effect. The MOS transistor degradation is caused by Si-H (hydrogen) bond breaking at the SiO2-Si interface due to the energetic hot electrons. The current theory and experiments suggest that the Si-H bond breaking is caused by two competing processes: the excitation due to the energetic hot electrons and the de-excitation by energy coupling between the vibrational modes of the Si-H bonds and the phonon modes of the Si lattice. The energy coupling between the Si-D (deuterium) bonds and the Si lattice (TO phonon) is much more efficient than that between the Si-H bonds and the Si lattice. Therefore the Si-D bonds are more robust than Si-H bonds, which is the so-called isotope effect. Based on this principle, the deuterium-treated MOS transistors exhibit much longer hot-carrier lifetime (over 50 times) than the traditional hydrogen treatment. Evidence shows that there is a potential for further improvement of MOS transistor lifetime by over 100 times, if the mechanisms for degradation and its isotope effect are understood. The characterization of the efficient energy coupling between the two vibrational modes is that their frequencies are the same or very close. The study of the energy coupling is vital to understand the mechanisms for degradation and its isotope effect. The proposed research program will focus on two thrusts: 1) Degradation mechanisms for deep-submicron MOS transistors from fundamental point of view and 2) Study of dynamic hot-carrierdegradation of MOS devices in CMOS inverters. In the first thrust, I will use Raman and Infrared (IR)spectroscopy to study the vibrational modes of the Si-H and Si-D bonds. The ultimate goal of theresearch program is to develop predictive principles from which the processing can be designed toachieve the maximum lifetime improvement for MOS transistors. In the second thrust, I will study thedeuterium isotope effect for transistors under the dynamic stress or AC stress, because the transistors areoperating in AC conditions in the real circuits. The proposed research builds upon and expands theresearch work that the PI is already undertaking.The educational component of this CAREER program seeks support for development of a newexperimental course, integrated circuit device fabrication, and focused educational outreach activitiesin Appalachian communities (underrepresented groups). With the support from the State of Kentuckythrough the Research Challenge Trust Fund (RCTF), a Device Fabrication Facility is under constructionat UK. A new experimental course focused on fabrication of integrated circuit devices will be developed,which is equivalent to similar courses in other universities in the US. The class is a hands-on lab coursewhere students have the opportunity to build semiconductor devices for integrated circuits. This class willfirst be taught in the Fall 2001 for senior undergraduate students and graduate students. Themultidisciplinary nature of this program will provide students with a unique environment for researchand learning. The goal is to build bridges between these traditional disciplines such as physics, materialsscience, and electrical engineering by conducting research and teaching through an integrated approach.The other component of the educational objectives involves the educational outreach activities targetedfor high school students from Eastern and Southern Kentucky including Appalachian communities. Oneof the objectives is to encourage those high school students to pursue high-tech career by presenting aseries of seminars in microelectronics. Another one is to offer an experimental project to teach them tobuild some useful digital circuits. The high school students will be recruited from the already establishedprogram, the Rogers Scholar Program organized by the Center for Rural Development, which the PIalready participates.