Analysis of surface defects in Si 1- y C y epilayers formed by the oversaturation of carbon
Analysis of surface defects in Si 1- y C y epilayers formed by the oversaturation of carbon
复制标题
碳过饱和形成的Si 1- y C y 外延层表面缺陷分析
DOI：
10.1088/0268-1242/30/11/114003
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发表时间：
2015
影响因子：
1.9
通讯作者：
Colston G
中科院分区：
文献类型：
--
作者：
Colston G
采用低成本的二硅烷和三甲基硅烷为前驱体，采用减压化学气相沉积方法在Si(0 0 1)衬底上生长了应变Si1−y Cy外延层。在应变外延层中实现了高达y=1.5%的替代C掺入，而在松弛层中观察到了更高的C含量，至少为2.4%。这些结果可与使用更高活性但昂贵的前体所获得的最高浓度相媲美。这些相对较高的C含量的外延层在整个生长过程中形成了缺陷，这归因于C原子的聚集，这导致了局域加速的非晶生长，从而在外延层表面形成了丘状。利用各种微观技术分析了这些表面缺陷的形成、大小和分布。这些结构缺陷的大小和密度都随着C含量和外延层厚度的增加而增加。在我们的固定生长时间层中，替代C组分高于1.5%会导致表面上的丘状熔合；随后发生非晶态生长，从而在晶态的Si1−y Cy外延层上形成非晶层，从而阻止进一步的外延或可靠的器件制造。这项研究的结果表明，假设生长足够薄的薄膜，可以在不需要昂贵和挥发性的前驱体或复杂的生长过程的情况下获得低于1.5%的替代C组分。
Strained Si 1− y C y epilayers have been grown on Si (001) by reduced pressure chemical vapor deposition, using low-cost precursors disilane and trimethylsilane. Substitutional C incorporation has been achieved in strained epilayers up to y= 1.5%, while higher C content of at least 2.4% is observed in relaxed layers. These results are comparable to the highest concentrations achieved using more highly reactive, but expensive, precursors. These relatively high C content epilayers were found to form defects throughout growth attributed to the clustering of C adatoms, which result in localized accelerated amorphous growth and, consequently, hillocks forming on the epilayer surface. The formation, size and distribution of these surface defects has been analyzed through the use of various microscopic techniques. The size and density of these structural defects increases with both C content and epilayer thickness. In our layers of fixed growth time, substitutional C compositions above 1.5% causes hillocks to fuse on the surface; subsequently amorphous growth occurs, which forms an amorphous layer over the crystalline Si 1− y C y epilayer and hence prevents further epitaxy or reliable device fabrication. The results of this investigation suggest that substitutional C composition of below 1.5% could be achieved without the need for expensive and volatile precursors or complex growth processes, assuming sufficiently thin layers are grown.