UHV／CVD硅外延的实时硼掺杂研究

本文利用超高真空化学气相沉积系统（UHV／CVD）在720℃Si（100）衬底上进行了实时B掺杂的硅外延,采用二次离子质谱仪（SIMS）,傅立叶红外光谱（FTIR）,扩展电阻仪（SRP）对外延层的性能进行研究,研究表明,720℃生长时已经实时掺入了B原子,1000℃退火5分钟后,外延层中B原子被激活,浓度达到10^17-10^18cm,且过渡层分布陡峭。     

UHV／CVD外延生长锗硅碳三元合金的应变研究

用真高真空化学气相沉积方法,在Si(100)衬底上生长掺C高达2．2％的Si1-x-yGexCy合金薄膜,外延层质量良好。用高分辨透射电子显微镜,X射线衍射,傅立叶红外吸收光谱以及拉曼光谱对外层进行了检测,结果表明：替代位C的加入,9明显缓解了宏观上的应变,但在合金中仍存在着微观应变。     

UHV／CVD外延生长锗硅碳三元合金的应变研究

用超高真空化学气相沉积方法,在Si(100)衬底上生长掺C高达2.2%的Si1-x-yGexCy合金薄膜,外延层质量良好。用高分辨透射电子显微镜,X射线衍射,傅立叶红外吸收光谱以及拉曼光谱对外延层进行了检测。结果表明替代位C的加入,明显缓解了宏观上的应变,但在合金中仍存在着微观应变。     

利用UHV／CVD技术在双层多孔硅上外延硅研究

利用 UHV/CVD技术 ,在较低的温度下 ,在阳极氧化形成的双层多孔硅上 ,成功地生长了单晶性好、厚度均匀、电阻率分布合适的硅单晶外延层。这为进一步研制 SOI材料与器件提供了所需的薄硅外延层。     

利用UHV／CVD技术在双层多孔硅上外延硅研究

利用ＵＨＶ／ＣＶＤ技术，在较低的温度下，在阳极氧化形成的双层多孔硅上，成功地生长了单晶性好、厚度均匀、电阻率分布合适的硅单晶外延层。这为进一步研制了ＳＯＩ材料与器件提供了所需的薄硅外延层。     

UHV/CVD生长锗硅材料的偏析现象

本文对利用超高真空CVD方法生长的Si1-xGex合金外延层中的锗表面分布情况和Ge在界面偏析现象进行了深入的研究.通过XPS和SIMS图谱的研究,指出表面由于锗的偏析,造成锗在体内和表面的含量不同,在低温时生长锗硅合金,表面氢原子的吸附可有效地抑制锗的偏析,但随着温度的升高,氢的脱附造成锗的偏析现象更加明显.     

新颖的超高真空CVD外延设备与低温低压硅外延研究

为实现低温低压外延新工艺，建立了一台具有多项原位监控功能的新颖的超高真空CVD（chemicalvapordeposition）外延设备，并用此设备，（100）和（111）硅片分别在550℃和650℃下由硅烷热解法成功地生长了硅外延层。高分辨率的横断面透射电镜（XTEM）照片表明，低温硅外延层中存在一些缺陷，这些缺陷都由衬底表面引起的，然后扩展进入外延层。此外，衬底｛100｝Si和｛111｝Si因晶向不同，不仅获得外延层所需的最低温度不同，而且外延层中的缺陷特征差异也很大。     

退火对UHVCVD外延生长锗硅碳三元合金的影响

采用傅立叶红外吸收光谱（FTIR）和X射线衍射（XRD）研究了超高真空化学气相沉积外延生长的Si1-x-yGexCy三元合金的热稳定性，在比较高的退火温度下（950度或以上），Si1-x-yGexCy中的替代位的C逐步形成SiC沉淀，减弱了应变的补偿作用，从而增大了合金中的应变，显示出不同于Si1-x-yGex的驰豫行为。     

改善UHV／CVD外延生长环境提高GeSi／Si材料性能有效方法

本阐述了应用国产ＵＨＶ／ＣＶＤ设备处延生长的ＧｅＳｉ／Ｓｉ材料碳、氧含同的原因,定量地分析了有害残余气体的成分,提出了改善处延生长环境提高ＧｅＳｉ／Ｓｉ材料性能的有效方法。     

超高真空化学气相淀积自组织生长锗量子点

采用超高真空化学气相淀积系统制备了小尺寸、高密度、纵向自对准的Ge量子点．通过TEM和AFM对埋层和上层量子点的形貌和尺寸分布进行了研究，对生长的温度和时间进行了优化．采用硼预淀积的方法得到了尺寸分布小于3％的均匀的圆顶形Ge量子点．采用低温光荧光测量了多层量子点的光学特性．在10K的PL谱可以观察到明显的蓝移现象，表明量子点中较强的量子限制效应．量子点非声子峰的半高宽约为46meV，表明采用UHV／CVD工艺生长的多层量子点具有较窄的尺寸分布．     

双生长室超高真空化学气相淀积系统的研制

本文介绍了中国科学院半导体研究所的双生长室超高真空化学气相淀积系统的工作原理、技术参数、结构、性能及特点。该系统具有双生长室、引入准分子激光和多态源等主要优点,是IV族半导体材料生长和研究的强有力工具。     

锗硅碳合金中碳的应变缓解效应研究

SiGeC三元合金成为近年来人们研究的热点之一。处于替代位置的碳可以缓解SiGe合金的应变,同时调节其能带,在能带工程上提供了更大的灵活性。本文利用UHV/CVD技术生长了掺碳达2.2%的锗硅碳合金,获得了良好的外延层质量,并对碳的应变缓解效应进行了研究。     

超高真空磁控溅射Co／Si多层膜的X射线衍射分析

采用Ｘ射线衍射分析表征了磁控溅射方法制备的Ｃｏ／Ｓｉ周期多层膜,由带折射修正的布喇格衍射定律导出多层膜周期厚度,对两组折射修正公式的计算结果进行对比,讨论了平均折射率修正值为负的原因,并应用薄膜光学理论分析小角Ｘ射线衍射谱中出现的一系列现象。     

Thermal Properties of GaN Films Grown on Si Substrates

GaN films grown on Si substrates by molecular beam epitaxy with different nitridation times have been investigated. The GaN/Si structural and optical properties were evaluated by transmission electron microscopy, X-ray diffraction, atomic force microscopy, and photoluminescence. The effective thermal conductivity of the GaN/Si system was obtained using the photoacoustic technique, and from these results the nitridation time dependence of the interface thermal conductivity (η) can be evaluated using a two-layer model. An optimal nitridation time for which the GaN crystal quality can be improved was obtained. The variation of the parameter η for different nitridation times can be related to the interface phonon scattering process by the presence of disorder at the GaN/Si interface.     

Investigation of diffusional intermixing in Si/Co/Ta system by Secondary Neutral Mass Spectrometry

Low temperature analysis of diffusion and intermixing of Co-Si systems are very important in applications for microelectronics and Ultra Large Scale Integration (ULSI). In this communication a comprehensive report has been given on degradation and diffusion processes in the Si(substrate)/Co(150 nm)/Ta(10 nm) system. The samples were prepared by DC magnetron sputtering and were annealed in argon ambient at several temperatures ranging from 400 to 623 K for various times. The composition of the samples was investigated by Secondary Neutral Mass Spectrometry (SNMS). The degradation/intermixing starts with fast (grain boundary (GB)) diffusion of the Si into the Co layer. After some incubation time Si atoms appear and spread over the Co/Ta interface. This amount of Si accumulated at the Co/Ta interface acts as a reservoir for back-diffusion into the Co layer from the Co/Ta interface through the slower grain boundaries. At higher temperatures the formation of a Co-Si phase was detected at the Co/Si and Co/Ta interface. Three different diffusion coefficients were calculated from the SNMS concentration-depth profiles using “Central-gradient” (CG) and “First-appearance” methods. The observed intermixing was interpreted as a mixture of different “C-type” grain boundary diffusion processes. Furthermore, the experimental results are also compared with computer simulations modelling the grain-boundary diffusion through different grain-boundary paths. From the SNMS profiles measured at different temperatures the activation energy of the GB interdiffusion coefficients was deduced using the “CG method”.     

Growth of GaN on SiC/Si substrates using AlN buffer layer by hot-mesh CVD

GaN films were grown on SiC/Si (111) substrates by hot-mesh chemical vapor deposition (CVD) using ammonia (NH₃) and trimetylgallium (TMG) under low V/III source gas ratio (NH₃/TMG = 80). The SiC layer was grown by a carbonization process on the Si substrates using propane (C₃H₈). The AlN layer was deposited as a buffer layer using NH₃ and trimetylaluminum (TMA). GaN films were formed and grown by the reaction between NH_x radicals, generated on a tungsten hot mesh, and the TMG molecules. The GaN films with the AlN buffer layer showed better crystallinity and stronger near-band-edge emission compared to those without the AlN layer.     

基于TiC_(0.5)N_(0.5)/Si_3N_4复相陶瓷基体的PVD及CVD涂层刀具性能

首先,以15vol%或25vol%的TiC0.5N0.5粉体为导电第二相,利用热压烧结法制备了TiC0.5N0.5/Si3N4复相陶瓷;然后,分别通过物理气相沉积(PVD)和化学气相沉积(CVD)技术在TiC0.5N0.5/Si3N4陶瓷刀具表面沉积了CrAlN和TiN/Al2O3/TiN涂层;最后,通过对TiC0.5N0.5/Si3N4刀具进行连续切削灰铸铁实验,研究了TiC0.5N0.5含量和涂层类型对刀具磨损特征的影响,并探讨了刀具的磨损机制。结果表明:TiC0.5N0.5含量的增加有利于提高TiC0.5N0.5/Si3N4复相陶瓷刀具基体的硬度和电导率,但对耐磨性和切削寿命的影响较小;采用PVD技术沉积CrAlN涂层时,随着TiC0.5N0.5含量的增加,涂层的厚度、结合强度和硬度都得到提高,涂层刀具的磨损性能显著提高,切削寿命也明显延长;而采用CVD技术沉积TiN/Al2O3/TiN涂层时,TiC0.5N0.5含量的变化对涂层的厚度、结合强度和硬度基本没有影响,TiN/Al2O3/TiN涂层刀具整体切削性能变化不大。CrAlN涂层和TiN/Al2O3/TiN涂层都可明显改善TiC0.5N0.5/Si3N4复相陶瓷刀具的耐磨性和切削寿命;相对于TiN/Al2O3/TiN涂层,CrAlN涂层具有更高的涂层硬度和粘着强度,但TiN/Al2O3/TiN涂层具有较大的涂层厚度,TiN/Al2O3/TiN涂层刀具表现出更加优异的耐磨性和切削寿命。TiC0.5N0.5/Si3N4复相陶瓷刀具的磨损机制以机械摩擦导致的磨粒磨损为主,伴随有少量的粘结磨损。