【作者】 李瑞珉；

【导师】 杜磊；

【作者基本信息】 西安电子科技大学 ， 材料学， 2006， 硕士

【摘要】 随着大量商用高性能半导体器件用于宇航、核能等领域，越来越多的未加固MOSFET需要在核辐射条件下工作，为了在保证使用的可靠性的同时尽可能的降低成本，人们迫切需要一种可靠，快速，成本低廉的无损伤辐照效应预测方法来代替传统的辐射退火晒选方法。本文介绍了MOS器件电离辐照效应及1／f噪声物理机制，在此基础上，进行了噪声与电离辐照相关性的试验，获取了大量辐照前后MOS器件的电参数及噪声参数数据，并对MOS器件抗辐照能力的1／f噪声表征进行了深入研究，取得了以下研究成果：1、对不同沟道类型和沟道尺寸的MOSFET进行了⁶⁰Coγ辐照实验，发现辐照前1／f噪声与辐照引起阈值电压漂移、跨导退化及栅泄漏电流增加之间有明显的相关性。理论分析表明，电离辐照在MOS器件栅氧化层中激发的电荷会被Si／SiO₂系统中缺陷所俘获形成陷阱电荷，这些陷阱电荷的存在导致器件电参数发生改变，严重的还引起器件的实效。由于1／f噪声反应了栅中缺陷数目的多少，也就是反映了栅氧质量的好坏，因此辐照前的1／f噪声与辐照后器件的电参数变化体现出相关性。2、基于界面陷阱形成的氢离子运动两步模型和反应过程的热力学平衡假设，推导了MOSFET经历电离辐照后氧化层空穴俘获与界面陷阱形成间关系的表达式。利用初始1／f噪声功率谱幅值与氧化层空穴俘获之间的联系，建立了辐照前的1／f噪声幅值与辐照诱生界面陷阱数量之间的半经验公式，并通过实验予以验证。本文研究结果表明，由于辐照诱生的氧化层内陷阱通过与分子氢作用而直接参与到界面陷阱的建立过程中，从而使界面陷阱生成数量正比于这种陷阱增加的数量，因此辐照前的l／f噪声功率谱幅值正比于辐照诱生的界面陷阱数量。本文结果为1／f噪声用作MOSFET辐照损伤机理研究的新工具，对其抗辐照性能进行无损评估提供了理论依据与数学模型，并且通过实验给予验证。更多还原

【Abstract】 MOS devices have to suffer from ionizing radiation as they are widely used in the environment of space, nuclear energy and nuclear weapon. The parameter defradation, half and /or full permanent damage even failure in function of MOS devices will occur due to the generation of radiation-induced oxide trapped charges and interface traps. In order to keep the devices work well in the environment of ionizing radiation, radiation-anneal techniques of ionizing radiation are generally used. The more important thing is that this method will induce some new latent defects in the device under test, let alone this method is expensive, time-waste and destructive. It is therefore useful to consider whether a simple, fast and nondestructive method can be defined to characterize the ability of MOS devices to restrain radiation.The method of characterizing ability of MOS devices to restrain radiation is thoroughly studied by analyzing the relationship between 1/f noise and radiation effects.1 The radiation experiments of MOSFETs, with different channel area and type, have been made using ⁶⁰Coγas radiation source. The results demonstrate that there are obvious relationships between 1/f noise of pre-radiation and the changes of threshold voltage and transconductance after radiation. The results also tell that the magnitude of 1/f noise becomes large with the dose of radiation adding, which predicates the more tapped charges induced by radiation and its distribution is also changed.2 Based on the two-step interface traps buildup model and the statistical thermodynamics mechanics of point defects in solids, a relation between the radiation induced increase of oxide hole-traps and the buildup of interface traps in MOSFET is proposed. Then, use the correlation between pre-irradiation 1/f noise power spectral density and post-irradiation oxide-trap charge, a sim-empirical expression between pre-irradiation 1/f noise and post-irradiation interface traps buildup is established. It is agree well with the experimental results. This model show that the process of interface traps buildup was influenced by the increasing of oxide hole-traps that could disassemble hydrogen into proton in irradiation. So, the magnitude of pre-irradiation 1/f noise direct ratio to post-irradiation interface-trap charge and sub-threshold slope.The work done above not only proving that the 1/f noise can play a important role in investigate MOSFET irradiation effects, but also providing a new nondestructive method to estimate MOSFET radiation response.更多还原