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Source of surface defects in silicon carbide epitaxial files and their elimination method

碳化硅外延锉表面缺陷的来源及消除方法

基本信息

批准号：
16560009
负责人：
OKADA Tatsuya
金额：
$ 2.66万
依托单位：
The University of Tokushima
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2007
项目状态：
已结题

项目摘要

Silicon carbide (SIC) has been attracting much attention because of its application to power devices exhibiting superior performance to conventional Si-based ones. large-area epitaxial films of high quality are essential for the fabrication of kV-class high-power SiC devices. However ; at the present stage, imperfections in epitaxial films including surface defects impose a limitation on high-yield production of such devices. When formed, some types of surface defect deteriorate device performance by lowering the breakdown voltage of p-n junctions by 20 to 40%. The major objectives of the present study are to investigate the source of surface defects at the substrate/epifilm interface by plan-view transmission electron microscopy (TEM) and to find a technique to eliminate crystallographic defects accompanying surface defects.We were successful in preparing plan-view TEM samples which contain the substrate/epifilm interface in the thinned area by removing almost the entire epifilm with … More reactive plasma-etching prior to the conventional ion-thinning from the substrate side. The source of surface defects was composed of an inclusion and partial dislocations. Energy dispersive X-ray (EDX) spectroscopy and micro-Raman analysis unraveled that the inclusions were very small particles of zirronia (ZrO_2). The thermal insulator in the chemical vapor deposition (CVD) furnace is the most suspicious origin of ZrO_2 particles. The ZrO_2 particles which fell onto the SiC substrate surface and were ncorporated into the epifilm may have acted as the source of partial dislocations, which resulted in the formation of surface defects.We propose that phase change induced by irradiation of ultra-short laser pulses may be applied to the elimination of defects in SiC epitaxial films. When femtosecond laser pulses are irradiated on the surface of SiC, periodic surface microstructures referred to as ripples are formed. In order to study the cross-sectional microstructures of ripples, we carried out TEM studies with particular attention on the crystal structure underlying ripples. A continuous amorphous layer approximately 10 to 50 nm thick was found to cover the topmost region of ripples. Less

碳化硅因其在功率器件中的应用表现出比传统硅基材料更优越的性能而备受关注。大面积高质量的外延薄膜是制造千伏级高功率碳化硅器件的关键。然而，在现阶段，包括表面缺陷在内的外延薄膜的缺陷限制了此类器件的高成品率生产。当形成时，某些类型的表面缺陷会使p-n结的击穿电压降低20%到40%，从而降低器件性能。本研究的主要目的是用平面式透射电子显微镜研究衬底/外延膜界面的表面缺陷的来源，并寻找一种消除伴随表面缺陷的结晶学缺陷的技术。我们用…去除了几乎整个外延膜，成功地制备了在薄区含有衬底/外延膜界面的平面式透射电子显微镜样品在传统的离子减薄之前，从衬底一侧进行更多的反应等离子刻蚀。表面缺陷的来源由夹杂物和部分位错组成。能量色散X射线能谱(EDX)和显微拉曼分析表明，夹杂物为极细小的氧化锆(ZrO2)颗粒。化学气相沉积(CVD)炉内的绝热层是氧化锆颗粒最可疑的来源。落在碳化硅衬底表面并结合成外延膜的氧化锆颗粒可能是部分位错的来源，从而导致表面缺陷的形成。我们认为，超短激光脉冲辐照引起的相变可用于消除碳化硅外延薄膜中的缺陷。当飞秒激光脉冲照射到碳化硅表面时，会形成周期性的表面微结构，称为波纹。为了研究波纹的截面微结构，我们进行了特别关注波纹背后的晶体结构的透射电子显微镜研究。在波纹的最顶端有一层连续的非晶层，厚度约为10~50 nm。较少