Oxidation behavior of ytterbium silicide

Si-rich ytterbium silicide was fabricated by through an arc-melting technique for applying use as a bond coat material in an environmental barrier coating system. Evaluation of its potential was accomplished through oxidation tests in dry air and an inert atmosphere. The experimental results showed that the changes in weight and morphologies of ytterbium silicide observed after the tests depended on the oxygen partial pressure. Extensive oxidation and weight gain occurred after oxidation in air. In order to apply this material for hot structures, improvement of the oxidation resistance is needed.     

Heteroepitaxial growth of Zn1−xCdxSe on cleavage-induced GaAs (110) surface in ultra high vacuum

Zn_1−xCd_xSe epitaxial growth by molecular beam epitaxy (MBE) on the GaAs (110) surface cleaved in ultra high vacuum (UHV) was investigated. The growth mode of Zn_1−x Cd_xSe on GaAs (110) was not a simple Stranski–Krastanow type. At initial growth stage, growth mode was two-dimensional type. However, as the growth proceeds three-dimensional island growth and two-dimensional growth modes compete. As a result, two kinds of structures were spontaneously formed on the surface, pyramidal-shaped islands and ridge structures aligned to the [1 0] direction. Anisotropic in-plane strain relaxation on (110) is suggested as the formation mechanism of such structures.     

Metal silicide-templated growth of quality Si films for Schottky-diodes

Quality Si films were grown on a metal silicide template and fabricated for a Schottky-diode. The thin metal was firstly deposited and reacted to the supplying Si and then formed the silicide layer, which is a template to grow quality Si film above it due to the lattice affinity to Si. Various types of metal (Co, Ni, and mixture of Co and Ni) were used as catalyst species. The morphological changes of Si grain sizes were systematically investigated. Two steps of Si supply condition were applied and revealed the formation of metal silicide phases and Si film growth.During the Si supply, Co was stable to form CoSi₂ and grew a crystalline Si (c-Si) film above it. However Ni firstly formed Ni rich silicide phases at low Si supply due to the fast Ni diffusion in Si. By increasing the Si supply, Ni diffusion has been staggered and formed NiSi₂ layer to grow a c-Si film above it. It has been also revealed that the NiSi₂ migration produced a c-Si film behind. Mixing of Co with Ni showed a stable silicide phase without a serious metal migration and improved the Si crystallinity providing an enhanced Schottky-diode performance.The investigation of silicide formation and quality Si film growth is presented. Transmission electron microscope analysis proves the volume growth of c-Si film above a metal disilicide of NiSi₂ or CoSi₂.     

离子束混合诱导稀土金属Ce与Si的界面反应及硅化物的形成

本文详细讨论了离子束混合下,Ce/Si〈100〉双层膜体系界面反应的动力学过程以及硅化物的形成规律.样品经150KeV Ar离子注入,辐照温度从LNT到300℃,剂量从5×X10~(14)到8.1×10~(16)Ar/cm~2.界面反应形成的硅化物为CeSi_2,其结构为体心正交结构.硅化物是分层生长的,厚度与注入剂量的平方根成线性关系,这说明界面反应是扩散控制的.与近贵金属/硅体系和难熔金属/硅体系相比较可以看出,稀土金属Ce/Si体系的相变过程与难熔金属/硅体系的相似;而混合的动力学行为与近贵金属/硅体系的相似.本文还讨论了化学驱动力和辐射增强扩散对混合的贡献.     

Influence of growth parameters on the microstructures of erbium films deposited on Si(111) substrates

Erbium films were grown on single crystal Si(111) substrates by electron beam vapor deposition. The microstructures of the erbium films were systematically investigated by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. Results indicate that the surface morphologies and microstructures of the erbium films with Si as substrates are susceptible to the substrate temperatures when the deposition rates are fixed. The pure erbium films with columnar grains were obtained at temperatures below 200 °C, but in the films grown at temperatures higher than 350 °C, some pinholes that are composed of erbium silicides were found. The pinholes have triangular shapes which is in accordance with the geometry of the underlying Si(111) substrate. The films grown at a substrate temperature equal or greater than 450 °C have cracks which would be formed due to the different shrinkage degree of erbium and silicon when the substrate temperature was cooled down to room temperature. The films grown at 200 °C show the (002) preferred orientation, which is consistent to the prediction by the theory of surface energy minimization. The deposition rate and deposition time are considered as factors to affect the reaction of the erbium film and the silicon substrate.     

纳米Al2O3/MO5Si3复合粉体的机械化学合成

以MoO3粉、Mo粉、Si粉及Al粉为原料,采用机械化学还原法原位合成了纳米Al2O3/Mo5Si3复合粉体,并对固态反应过程进行了探讨.结果显示,球磨30 h后复合粉体的主要物相为Mo5Si3、Mo3Si及Al2O3,反应为机械诱导的自蔓延反应;随产物中Al2O3含量增加,Si烧损增加,复合粉体中Mo3Si含量增加;...     

Low-temperature processing of shallow junctions using epitaxial and polycrystalline CoSi2

Cobalt disilicide is grown epitaxially on (100) Si from a 15 nm Co/2 nm Ti bilayer by rapid thermal annealing (RTA) at 900°C. Polycrystalline CoSi₂ is grown on (100) Si using a 15 nm Co layer and the same annealing condition. Silicide/p⁺-Si/n-Si diodes are made using the silicide as dopant source:¹¹B⁺ ions are implanted at 3.5–7.5 kV and activated by RTA at 600–900°C. Shallow junctions with total junction depth (silicide plus p⁺ region) measured by high-resolution secondaryion mass spectroscopy of 100 nm are fabricated. Areal leakage current densities of 13 nA/cm² and 2 nA/cm² at a reverse bias of -5V are obtained for the epitaxial silicide and polycrystalline silicide junctions, respectively, after 700°C post-implant annealing.     

Investigation of MOSFET operation in bipolar mode

The work is concerned with the properties of conventional MOSFET in bipolar mode of operation. It is shown that the base current can provide useful information about interface trap density at the Si–SiO₂ interface. The new device characteristics are found promising for use in low-voltage low-power logic circuits.     

超大规模集成电路快速热处理技术

本文介绍了快速热处理技术的研究成果.包括:RHT设备,高剂量注入硅的RTA机理与最佳RTA条件选择,以及浅PN结制造,硅化物形成,BPSG回流和薄氧化层的快速氮化等RTP技术.     

离子束合成的钇硅化物结构相变研究

为了获得高品质的欧姆接触和线路连接材料，利用离子注入方法在n型单晶Si(111)基底上制备了钇硅化物，并对其在高真空下红外光辐照处理过程中的结构相变进行了研究，X射线衍射测量表明，在Y离子注入过程中已形成了部分六方相YSi2，800℃下红外光辐照处理30min后YSi2呈现出择优结晶取向，从辐照过程中原位测量样品的方块电阻变化发现，当温度升至160℃时，Y与Si反应首先形成了斜方相YSi，YSi/YSi2的相转变出现在240℃，随温度的进一步升高，Y原子完全与Si原子发生反应，形成了结晶取向良好的六方相YSi2。