氮等离子体处理对SiC MOS栅氧化膜TDDB特性的影响

发布时间：2018-03-07 06:12

本文选题：4H-SiC　切入点：MOS电容　出处：《大连理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：与硅相比,第三代半导体碳化硅拥有极好的性质,比如高热导率,高电子迁移率等,同时也是唯一一种能够通过热氧化过程生长氧化膜的化合物半导体。然而直接通过热氧化过程制作的4H-SiC MOS器件有着界面缺陷过多,氧化膜可靠性欠佳的问题。其原因在于热氧化生成的氧化膜中存在着许多缺陷,这些缺陷导致氧化膜击穿所需要的激活能减小,降低了氧化膜电应力的承受能力。因此减少氧化膜中的缺陷,提高氧化膜可靠性就成为了SiC MOSFET研究领域的关键问题。本文使用电子回旋共振(ECR)氮等离子体处理工艺对通过热氧化过程形成的氧化膜进行处理,制作成为4H-SiC MOS结构。通过I-V测试发现,通过ECR氮等离子体处理工艺,SiO2/4H-SiC的势垒高度有效地提高至2.67 eV,接近理论值2.7 eV,击穿场强达到了10.90 MV/cm。采用阶跃电流经时击穿(SCTDDB)方法研究了ECR氮等离子体处理对4H-SiC MOS氧化膜经时击穿(TDDB)行为的影响。实验发现,ECR氮等离子体能够有效提高氧化膜的击穿电荷量与寿命,与未经过当等离子体处理的样品相比,经过处理的样品击穿电荷量与寿命分别提高了10-100倍和3-4个数量级。同时,本文还发现经过ECR氮等离子体处理后,样品的耐受电场强度的能力有所提高,而且样品的均一性有了很大提高,很小场强下就会被击穿的样品被消除,样品的击穿场强分布在一个较窄的范围内。为了解释ECR氮等离子体处理对于4H-SiC MOS样品TDDB行为的影响,本文使用了X射线光电子能谱(XPS)测试手段对4H-SiC MOS样品的物理性质进行分析,结果表明,ECR氮等离子体处理能够有效消除由于不完全氧化而产生的缺陷,钝化界面,因此提高了氧化膜击穿所需要的激活能,从而提高了样品击穿电荷量与寿命。以上结果表明,ECR氮等离子体处理能够有效降低4H-SiC MOS栅氧化膜中的缺陷,提高样品的击穿电荷量与寿命,提高样品的均一性以及对电场应力的耐受能力,改善了4H-SiC MOS栅氧化膜的可靠性。
[Abstract]:Compared with silicon, the third generation of semiconductor silicon carbide has excellent properties, such as high thermal conductivity, high electron mobility, and only through a thermal oxidation process of oxide film growth of compound semiconductor. However directly through the 4H-SiC MOS device made of a thermal oxidation process of interface defects are excessive, the problem of poor reliability of oxide film the reason is that. There are a lot of defects formed by thermal oxidation in the oxide film, these defects lead oxide film breakdown required activation energy decreased, reducing the oxidation film ability to withstand stress. Thus reducing defects in oxide film, improve the reliability of the film becomes the key problem of SiC MOSFET research field. This paper use electron cyclotron resonance (ECR) plasma treatment process of nitrogen formed by thermal oxidation process of the oxide film, made 4H-SiC MOS structure by I-V test. Found by ECR plasma treatment, the barrier height of SiO2/4H-SiC effectively increased to 2.67 eV, close to the theoretical value of 2.7 eV, the breakdown strength reached 10.90 MV/cm. with step current time breakdown (SCTDDB) method to study the ECR of nitrogen plasma treatment on 4H-SiC MOS oxide TDDB (TDDB) the effect of experiments. Found that ECR plasma can effectively improve the breakdown of charge and life on film, and has not been compared when the plasma treated sample, after the sample breakdown of charge and life treatment were increased 10-100 times and 3-4 orders of magnitude. At the same time, this paper also found that after ECR nitrogen plasma treatment, tolerance, electric field strength of samples the increased and uniformity of the samples has been greatly improved, a small electric field will be the breakdown of samples is eliminated and the breakdown strength of samples distributed in a narrow Range. In order to explain the effect of ECR treatment for 4H-SiC MOS nitrogen plasma samples of TDDB behavior, this paper uses X ray photoelectron spectroscopy (XPS) of 4H-SiC MOS sample physical property testing methods were analyzed, the results show that the ECR plasma treatment can effectively eliminate the defects caused by the incomplete oxidation passivation interface, so the activation energy of the oxide film breakdown to improve, thereby improving the sample breakdown of charge and life. These results indicate that ECR nitrogen plasma treatment can effectively reduce the defects of 4H-SiC MOS gate oxide film, improve the breakdown of charge and life samples, improve the uniformity of the samples and the ability to tolerate stress field, improve the reliability of 4H-SiC MOS gate oxide.

【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN386

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