Measurement of process-induced defects in Si sub-micron devices by combination of EDMR and TEM
Measurement of process-induced defects in Si sub-micron devices by combination of EDMR and TEM
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结合 EDMR 和 TEM 测量硅亚微米器件中工艺引起的缺陷
DOI：
10.1051/epjap:2004123
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Y. Mochizuki
中科院分区：
文献类型：
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作者：
T. Umeda;A. Toda;Y. Mochizuki
工艺诱导缺陷是现代亚微米硅LSI的一个严重问题。为了表征这种缺陷，两种不同的技术是有用的：电检测磁共振(EDMR)和透射电子显微镜(TEM)，它们分别可以检测小(点)缺陷和扩展缺陷。我们应用EDMR和TEM研究了动态随机存取存储器(DRAM)单元中缺陷引起的泄漏电流问题。对于我们的动态随机存储器样品(0.2 5-μm规则系列)，虽然透射电子显微镜没有发现扩展的缺陷，但能谱成功地检测到了两种类型的点缺陷：V2+Ox(Si双空位-氧复合体)和更大的Si空位(至少大于V6)。我们确认这些缺陷是DRAM泄漏电流的来源。观察到的缺陷是由离子注入过程形成的，但比体硅晶体中的缺陷更热稳定。这种增强的稳定性的起源归因于LSI中氧原子的存在和强烈的机械应变。为了弄清LSI结构中复杂应变的来源，我们可以用会聚束电子衍射(CBED)的方法直接测量DRAM样品中的局域应变分布，这为我们理解工艺缺陷的形成机制提供了有价值的线索。
Process-induced defects are a serious issue for modern sub-micron Si LSIs. To characterize such defects, two different techniques are useful: electrically detected magnetic resonance (EDMR) and transmission electron microscope (TEM), which can detect small (point) and extended defects, respectively. We applied EDMR and TEM to the issue of defect-induced leakage currents in dynamic-random-access memory (DRAM) cells. For our DRAM samples (a 0.25-μm-rule series), although TEM showed no extended defects, EDMR successfully detected two types of point defects: V 2 +O x (Si divacancy-oxygen complexes) and larger Si vacancies (at least larger than V 6 ). We confirmed that these defects are the source of DRAM leakage currents. The observed defects were formed by ion implantation processes, but were more thermally stable than those in bulk Si crystals. The origins of this enhanced stability are attributed to the presence of oxygen atoms and a strong mechanical strain in LSIs. To clarify the origin of the complicated strain in LSI structures, we can directly measure the local-strain distribution in DRAM samples by means of convergent-beam electron diffraction (CBED) using TEM, which provides us with a valuable hint for understanding the formation mechanism of process-induced defects.