【作者】 董尧君；

【导师】 吴雪梅； 诸葛兰剑；

【作者基本信息】 苏州大学 ， 凝聚态物理学， 2012， 硕士

【摘要】 随着MOSFETs的尺寸不断缩小，二氧化硅的厚度也随之不断减小，但当其物理厚度接近1nm时会有明显的量子遂穿效应。为了避免量子遂穿，需要使用高k材料来取代传统的SiO₂栅介质，这样可以在保持可靠的物理厚度下，依然具有良好的器件性能。高k材料作为栅介质SiO₂的替代者备受关注，且铪基高k材料已经被成功利用在半导体工艺中。铪基高k材料由于其具有较高的介电常数、较高的结晶温度、较好的热稳定性以及合适的禁带宽度等特性，吸引了越来越多的学者对其进行研究，从而成为一个热门的研究领域。MOSFETs工艺中，退火是必不可少的一道工艺。由于退火后会对薄膜的结构产生影响，从而改变其电学特性。所以本文主要研究了不同退火条件对高k材料的物性影响。利用XRD、XPS、SEM、AFM和Raman等分析测试手段对薄膜进行结构表征；测试薄膜的CV和IV电学特性，分析了其电容值、平带电压和漏电流。首先利用原子层沉积系统（ALD）沉积了超薄的HfO₂薄膜，先后分别在不同退火温度和退火气氛下进行退火处理，研究HfO₂薄膜的结构和电学特性在不同退火条件下的变化；再利用双离子束沉积系统（DIBSD）制备了HfTaO薄膜，并对其进行退火处理，研究退火对其结构和电学特性的影响。实验及测试分析：（1）利用ALD沉积HfO₂薄膜后在不同退火温度下退火，研究了退火温度对HfO₂薄膜的结构及电学特性的影响；（2）在不同退火气氛下对ALD制备的HfO₂薄膜进行退火，在氮气中退火后的薄膜有少量的氮被掺入到HfO₂薄膜中，具有较佳的稳定性和电学特性，且薄膜中缺陷少；（3）采用DIBSD制备的HfO₂掺杂Ta元素的HfTaO薄膜的结晶温度要远高于纯HfO₂的结晶温度，退火后薄膜的电容值虽然有所减小，但是氧化层缺陷得到一定的消除，且漏电流也减小，薄膜致密性增强。更多还原

【Abstract】 With the dimensions of MOSFETs shrinking, the thickness of the silicon oxide hasbeen scaled down. However, the thickness of the silicon oxide scaling down below1nmwould cause quantum tunneling. In order to avoid the quantum tunneling, high k materialsare realized to replace the traditional SiO₂gate dielectric, which can keep wellperformance of MOSFETs under reliable physical thickness. High k materials haveattracted much attention and the Hf-based materials have been successful used insemiconductor technology. Hf-based materials, which have higher dielectric constant, highcrystallization temperature, good thermal stability and suitable band gap, have attractedmore and more scholars to investigate them.Annealing is essential in MOSFETs process. The structure of the high k films changeduring the annealing process, which would influence the electrical characteristics.Therefore, we investigated the effect of different annealing conditions on thecharacteristics of high k films. The structures of the high k films in relation to theannealing process were examined by XRD, XPS, SEM, AFM, Raman and so on. Besides,the influence of annealing on capacitance, flat band voltage and leakage current of high kfilm has been investigated, which is extract from CV and IV characteristics. Firstly, ultrathin HfO₂films grown by Atomic layer deposition （ALD） were annealed in differenttemperatures and atmospheres. The variation of structure and electrical characteristics ofHfO₂films were investigated. In addition, HfTaO films were deposited by Dual Ion BeamSputtering Deposition （DIBSD） technique, then proceeding with annealing on the filmsafter deposition and analyzing the structure and electrical characteristics.The experimental and analysis results indicated that:（1） HfO₂films grown by ALD have been annealed in different temperatures, and the influence of annealing temperatureon the structure and electrical characteristics of HfO₂films are investigated,（2） after theHfO₂film annealed in nitrogen, which is grown by ALD, there is a little N doped in HfO₂.The films performed better thermal stability and electrical characteristics, which due to theless traps and better densification,（3） the crystallization temperature of HfTaO filmsdeposited by DIBSD is much higher than the pure HfO₂films. Although the capacitancedecreased a little, the oxide traps and the leakage both reduced and the densification offilms enhanced.更多还原