Ti-Si-N复合膜的界面相研究

为了揭示Ti_Si_N复合膜中Si₃N₄界面相的存在方式及其对薄膜力学 性能的影响 ，采用x射线衍射仪、高分辨透射电子显微镜、俄歇电子能谱仪和显微硬度仪对比研究了磁 控溅射Ti_Si_N复合膜和TiN/Si₃N₄多层膜的微结构和力学性能. 实 验结果表明 ，Ti_Si_N复合膜均形成了Si₃N₄界面相包裹TiN纳米晶粒的微结构. 其中低Si 含量的Ti_Si_N复合膜中Si₃N₄界面相的厚度小于1nm，且以晶体态 存在，薄膜 呈现高硬度. 而高Si含量的Ti_Si_N复合膜中的Si₃N₄界面相以非晶 态存在，薄 膜的硬度也相应降低. 显然，Ti_Si_N复合膜中Si₃N₄界面相以晶体 态形式存在 是薄膜获得高硬度的重要微结构特征，其强化机制可能与多层膜的超硬效应是相同的. 关键词： Ti－Si－N复合膜 界面相 微结构 超硬效应     

Synthesis and characterization of superhard Ti-Si-N films obtained in an inductively coupled plasma enhanced chemical vapor deposition (ICP-CVD) with magnetic confinement

Using a novel inductively coupled plasma enhanced chemical vapor deposition (ICP-CVD) with magnetic confinement system, Ti-Si-N films were prepared on single-crystal silicon wafer substrates by sputtering Ti and Si (5 at.%:1 at.%) alloyed target in argon/nitrogen plasma. High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM), atomic force microscopy (AFM) and Nano Indenter XP tester were employed to characterize nanostructure and performances of the films. These films were essentially composed of TiN nanocrystallites embedded in an amorphous Si₃N₄ matrix with maximum hardness value of 44 GPa. Experimental results showed that the film hardness was mainly dependent on the TiN crystallite size and preferred orientation, which could be tailored by the adjustment of the N₂/Ar ratio. When the N₂/Ar ratio was 3, the film possessed the minimum TiN size of 10.5 nm and the maximum hardness of 44 GPa.     

Effect of annealing temperature on microstructure, hardness and adhesion properties of TiSixNy superhard coatings

A series of TiSi_xN_y superhard coatings with different Si contents were prepared on M42 steel substrates using two Ti and two Si targets by reactive magnetron sputtering at 500 °C. These samples were subsequently vacuum-annealed at 500, 600, 700, 800 and 900 °C, respectively. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), microindenter, Rockwell hardness tester and scratch tester were applied to investigate the microstructure, phase configuration, hardness and adhesion properties of as-deposited and annealed samples. The results indicated that there were two bonds, TiN and Si₃N₄, in all presently deposited TiSi_xN_y thin films, that structure was nanocomposite of nanocrystalline (nc-) TiN embedded into amorphous Si₃N₄ matrices. Annealing treatment below 900 °C played a little role in microstructure and hardness of the coatings although it greatly affected those of steel substrates. The film-substrate adhesion strength was slightly increased, followed by an abrupt decrease with increasing annealing temperature. Its value got to the maximum at 600 °C. Annealing had little effect on the friction coefficient with its value varying in the range of 0.39-0.40.     

Chemistry and microstructure of PLD (Ti,Al)CxN1-x coatings deposited at room temperature

The aim of the present work was the improvement of titanium-aluminium nitride (TiAlN) coatings by the solid-solution hardening with carbon atoms leading to titanium-aluminium carbon-nitride (Ti,Al)C_xN_1-x coatings with varying carbon (x) and nitrogen contents. The request of low deposition temperatures necessary for the coating of heat sensitive materials like tool steels of high hardness and polymers was reached by the application of the room temperature pulsed laser deposition (PLD) technique. A Nd:YAG laser of 1064 nm wavelength operated at two different laser pulse energies was used in the ablation experiments of pure TiAl targets (50 at.% Al) in various C₂H₂-Ar gas mixtures. Different pulse energies of the laser resulted in changes of the ratio of Ti/Al atoms in the grown coatings. Furthermore, the results reveal a strong proportionality of the gas mixture to the C and N content of the coatings. In the coatings deposited at low C₂H₂ gas flows the XRD investigations showed crystalline phases with fcc TiN type lattices, whereas high acetylene flows during deposition resulted in the formation of fully amorphous coatings and carbon precipitation or cluster boundaries found in Raman investigations. PACS 81.15.Fg; 46.55.+d     

Structure and mechanical properties of reactive sputtering CrSiN films

CrSiN films with various Si contents were deposited by reactive magnetron sputtering using the co-deposition of Cr and Si targets in the presence of the reactive gas mixture. Comparative studies on microstructure and mechanical properties between CrN and CrSiN films with various Si contents were carried out. The structure of the CrSiN films was found to change from crystalline to amorphous structure as the Si contents increase. Amorphous phase of Si₃N₄ compound was suggested to exist in the CrSiN film. The growth of films has been observed from continuous columnar structure, granular structure to glassy-like appearance morphology with the increase of silicon content. The film fracture changed from continuous columnar structure, granular structure to glassy-like appearance morphology with the increase of silicon content. Two hardness peaks of the films as function of Si contents have been discussed.     

Characterization and properties Ti-Al-Si-N nanocomposite coatings prepared by middle frequency magnetron sputtering

TiN-containing amorphous Ti-Al-Si-N (nc-TiN/a-Si₃N₄ or a-AlN) nanocomposite coatings were deposited by using a modified closed field twin unbalanced magnetron sputtering system which is arc assisted and consists of two circles of targets, at a substrate temperature of 300 °C. XRD, XPS and High-resolution TEM experiments showed that the coatings contain TiN nanocrystals embedded in the amorphous Si₃N₄ or AlN matrix. The coatings exhibit good mechanical properties that are greatly influenced by the Si contents. The hardness of the Ti-Al-Si-N coatings deposited at Si targets currents of 5, 8, 10, and 12 A were 45, 47, 54 and 46 GPa, respectively. The high hardness of the deposited Ti-Al-Si-N coatings may be own to the plastic distortion and dislocation blocking by the nanocrystalline structure. On the other hand, the friction coefficient decreases monotonously with increasing Si contents. This result would be caused by tribo-chemical reactions, which often take place in many ceramics, e.g. Si₃N₄ reacts with H₂O to produce SiO₂ or Si(OH)₂ tribolay-layer.     

Influence of silicon on the microstructure and mechanical properties of Zr-Si-N composite films

A series of Zr-Si-N composite films with different Si contents were synthesized in an Ar and N₂ mixture atmosphere by the bi-target reactive magnetron sputtering method. These films’ composition, microstructure and mechanical properties were characterized by energy dispersive spectroscopy, X-ray diffraction, scanning electron microscopy, atomic force microscopy and nanoindentation. Experimental results revealed that after the addition of silicon, Si₃N₄ interfacial phase formed on the surface of ZrN grains and prevented them from growing up. Zr-Si-N composite films were strengthened at low Si content with the hardness and elastic modulus reaching their maximum values of 29.8 and 352 GPa at 6.2 at% Si, respectively. With a further increase of Si content, the crystalline Zr-Si-N films gradually transformed into amorphous, accompanied with a remarkable fall of films’ mechanical properties. This limited enhancement of mechanical properties in the Zr-Si-N films may be due to the low wettability of Si₃N₄ on the surface of ZrN grains.     

Synthesis and characterization of a large amount of branched Ni2Si nanowires

A large amount of Ni₂Si nanowires sheathed with amorphous silicon oxide has been generated from Ni substrates, for the first time, by thermal chemical vapor deposition using SiH₄ gas at 500 °C. The Ni₂Si nanowires obtained possess substantial amounts of branches (about 2-m length) grown on the main stems (about -–30 80nm diameter and -–10 20m length). High-resolution transmission electron microscopy and electron diffraction have revealed the orthorhombic Ni₂Si phase and the orientation. At the tail end along the branch grown on a stem an amorphous phase was also observed. The Raman spectrum was further used to characterize the product. A possible growth process of the branched Ni₂Si nanowires is briefly discussed. PACS 81.05.Bx; 81.07.Bc; 81.15.Gh; 87.64.Ee; 87.64.Je     

Thermal stability and electrical properties of Zr silicate films for high-k gate-dielectric applications, as prepared by pulsed laser deposition

Zirconium silicate films with high thermal stability and good electrical properties have been prepared on n-Si(100) substrates and commercially available Pt-coated Si substrates to fabricate metal–insulator–metal (MIM) structures by the pulsed laser deposition (PLD) technique using a Zr_0.69Si_0.31O_2- ceramic target. Rapid thermal annealing (RTA) in N₂ was performed. X-ray diffraction indicated that the films annealed at 800 °C remained amorphous. Differential thermal analysis revealed that amorphous Zr silicate crystallized at 830 °C. X-ray photoelectron spectroscopy showed that RTA annealing of Zr silicate films at 900 °C led to phase separation. The dielectric constant has been determined to be about 18.6 at 1 MHz by measuring the Pt/Zr silicate/Pt MIM structure. The equivalent oxide thicknesses (EOTs) and the leakage-current densities of films with 6-nm physical thickness deposited in O₂ and N₂ ambient were investigated. An EOT of 1.65 nm and a leakage current of 31.4 mA/cm² at 1-V gate voltage for the films prepared in N₂ and RTA annealed in N₂ at 800 °C were obtained. An amorphous Zr-rich Zr silicate film fabricated by PLD looks to be a promising candidate for future high-k gate-dielectric applications. PACS 77.55.+f; 81.15.Fg; 73.40.Qv     

Pulsed laser deposition of zirconium silicate thin films as candidate gate dielectrics

Thin films of zirconium silicate Zr_xSi_1-xO₂ (with x=0.69), a material that has been suggested as a possible high-k dielectric, are deposited on silicon wafers by pulsed laser deposition (PLD) under different deposition and post-annealing conditions. The morphology and electrical properties of these films are characterized. It is shown that the films remain amorphous after an ex situ rapid thermal annealing (RTA) at temperatures as high as 800 °C. For the 6 nm thick film deposited at 300 °C in an O₂ ambient with a N₂ ambient post-RTA at 500 °C for 5 min, the equivalent oxide thickness (EOT) is 1.9 nm, as evaluated from capacitance-voltage (C–V) measurements. The samples prepared with the N₂ ambient post-RTA show a slightly higher leakage current than that for samples annealed in the O₂ ambient. For the films deposited in N₂, the smallest EOT of 1.1 nm is obtained, and the films have fair electrical properties in spite of the high interface state density and relatively higher leakage. PACS 77.55.+f; 81.15.Fg; 81.40.Ef     

Ultra-thin a-SiNx protective overcoats for hard disks and read/write heads

This paper reports that amorphous silicon nitride (a-SiNx) overcoats were deposited at room temperature by microwave ECR plasma enhanced unbalanced magnetron sputtering. The 2 nm a-SiNx overcoat has better anti-corrosion properties than that of reference a-CNx overcoats (2-4.5 nm). The superior anti-corrosion performance is attributed to its stoichiometric bond structure, where 94.8% Si atoms form Si-N asymmetric stretching vibration bonds. The N/Si ratio is 1.33 as in the stoichiometry of Si3N4 and corresponds to the highest hardness of 25.0 GPa. The surface is atomically smooth with RMS < 0.2 nm. The ultra-thin a-SiNx overcoats are promising for hard disks and read/write heads protective coatings.     

TiN和Ti1-xSixNy薄膜的微观结构分析

使用x射线衍射(XRD)、x射线光电子谱(XPS)、高分辨透射电子显微镜(HRTEM)和原子力显微镜（AFM）多种观测手段分析了TiN薄膜和Ti_1-xSi_xN_y纳米复合薄膜的微观结构.实验分析证明Ti_1-xSi_xN_y薄膜是由直径为3—5nm的纳米晶TiN和非晶Si₃N₄相构成，并且Ti_1-xSi_{x关键词： 纳米复合薄膜 自由能 表面粗糙度 TiN 1-x}Si_xN_y')" href="#">Ti_1-xSi_xN_y     

Effect of Si in reactively sputtered Ti-Si-N films on structure and diffusion barrier performance

34 Si₂₃N₄₃ (b3) and Ti₃₅Si₁₃N₅₂ (c3), are synthesized by reactively sputtering a Ti₅Si₃ or a Ti₃Si target, respectively. The silicon-lean film (c3) has a columnar structure closely resembling that of TiN. As a diffusion barrier between a shallow Si n⁺p junction diode and a Cu overlayer, this material is effective up to 700 °C for 30 min annealing in vacuum, a performance similar to that for TiN. The silicon-rich (b3) film contains nanocrystals of TiN, randomly oriented and embedded in an amorphous matrix. A film of (b3) maintains the stability of the same diode structure up to 850 °C for 30 min in vacuum. This film (b3) is clearly superior to TiN or to (c3). Similar experiments performed with Al instead of Cu overlayers highlight the importance of the thermodynamic stability of a barrier layer and demonstrate convincingly that for stable barriers the microstructure is a parameter that directly determines the barrier performance. Received: 18 November 1996/Accepted: 22 January 1997     

纳米非晶氮化硅键态结构的X射线径向分布函数研究

本文用X射线径向分布函数法研究了室温到1000℃不同退火条件下的纳米非晶氮化硅样品的微结构和键合特征。观察到占庞大体积百分数界面不是“gas-like”结构,而是与非晶纳米粒子不同的新的短程序结构。Si—N键长和最近邻原子配位数(CN)均比传统Si₃N₄小,并存在大量的Si悬键和不饱和键。纳米氮化硅与传统Si₃N₄饱和共价键不同,是含有大量非饱和键和悬键的非典型共价键结构。由于键配位的不饱和特征,纳米非晶氮化硅的分子式应写作Si_3-xN_4-y。纳米非晶氮化硅出现强极性与非饱和键和悬键有密切的关系。 关键词：     

Crystallization of amorphous Si3N4 and superhardness effect in HfC/Si3N4 nanomultilayers

HfC/Si₃N₄ nanomultilayers with various thicknesses of Si₃N₄ layer have been prepared by reactive magnetron sputtering. Microstructure and mechanical properties of the multilayers have been investigated. The results show that amorphous Si₃N₄ is forced to crystallize and grow coherently with HfC when the Si₃N₄ layer thickness is less than 0.95 nm, correspondingly the multilayers exhibit strong columnar structure and achieve a significantly enhanced hardness with the maximum of 38.2 GPa. Further increasing Si₃N₄ layer thickness leads to the formation of amorphous Si₃N₄, which blocks the coherent growth of multilayer, and thus the hardness of multilayer decreases quickly.     

Si3N4的晶体化和ZrN/Si3N4纳米多层膜的超硬效应

研究了Si₃N₄层在ZrN/Si₃N₄纳米多层膜中的晶化现象及其对多层膜微结构与力学性能的影响. 一系列不同Si₃N₄层厚度的ZrN/Si₃N₄纳米多层膜通过反应磁控溅射法制备. 利用X射线衍射仪、高分辨透射电子显微镜和微力学探针表征了多层膜的微结构和力学性能. 结果表明，由于受到ZrN调制层晶体结构的模板作用，溅射条件下以非晶态存在的Si₃N₄层在其厚度小于0.9 nm时被强制晶化为NaCl结构的赝晶体，ZrN/Si₃N₄纳米多层膜形成共格外延生长的柱状晶，并相应地产生硬度升高的超硬效应. Si₃N₄随层厚的进一步增加又转变为非晶态，多层膜的共格生长结构因而受到破坏，其硬度也随之降低.     

Si-nanostructures formation in amorphous silicon nitride SiNx:H deposited by remote PECVD

The formation of silicon nanoclusters embedded in amorphous silicon nitride (SiN_x:H) can be of great interest for optoelectronic devices such as solar cells. Here amorphous SiN_x:H layers have been deposited by remote microwave-assisted chemical vapor deposition at 300 °C substrate temperature and with different ammonia [NH₃]/silane [SiH₄] gas flow ratios (R=0.5−5). Post-thermal annealing was carried out at 700 °C during 30 min to form the silicon nanoclusters. The composition of the layers was determined by Rutherford back scattering (RBS) and elastic recoil detection analysis (ERDA). Fourier transform infrared spectroscopy (FTIR) showed that the densities of SiH (2160 cm⁻¹) and NH (3330 cm⁻¹) molecules are reduced after thermal annealing for SiN:H films deposited at flow gas ratio R>1.5. Breaking the SiH bonding provide Si atoms in excess in the bulk of the layer, which can nucleate and form Si nanostructures. The analysis of the photoluminescence (PL) spectra for different stoichiometric layers showed a strong dependence of the peak characteristics (position, intensity, etc.) on the gas flow ratio. On the other hand, transmission electron microscopy (TEM) analysis proves the presence of silicon nanoclusters embedded in the films deposited at a gas flow ratio of R=2 and annealed at 700 °C (30 min).     

AlN/Si3N4纳米多层膜的外延生长与力学性能

采用射频磁控溅射方法制备单层AlN, Si₃N₄薄膜和不同调制周期的AlN/Si₃N₄纳米多层膜.采用X射线衍射仪、高分辨透射电子显微镜和纳米压痕仪对薄膜进行表征.结果发现,多层膜中Si₃N₄层的晶体结构和多层膜的硬度依赖于Si₃N₄层的厚度.当AlN层厚度为4.0nm、 Si₃N₄层厚度 关键词： 3N₄纳米多层膜')" href="#">AlN/Si₃N₄纳米多层膜 外延生长 应力场 超硬效应     

High‐performance a‐Si1–xOx:H/c‐Si heterojunction solar cells realized by the a‐Si:H/a‐Si1–xOx:H stack buffer layer

We used amorphous silicon oxide (a‐Si_1–xO_x:H) and microcrystalline silicon oxide (µc‐Si_1–xO_x:H) as buffer layer and p‐type emitter layer, respectively, in n‐type silicon hetero‐junction (SHJ) solar cells. We proposed to insert a thin (2 nm) intrinsic amorphous silicon (a‐Si:H) thin film between the thin (2.5 nm) a‐Si_1–xO_x:H buffer layer and the p‐layer to form a stack buffer layer of a‐Si:H/a‐Si_1–xO_x:H. As a result, a high open‐circuit voltage (V_OC) and a high fill factor (FF) were obtained at the same time. Finally, a high efficiency of 19.0% (J_SC = 33.46 mA/cm², V_OC = 738 mV, FF = 77.0%) was achieved on a 100 μm thick polished wafer using the stack buffer layer.

     

The effects of Si3N4 interlayer on the thermal stability and hardness of Ti/TiNx (x = 0.5-1) nanolayered coatings

The polycrystalline Ti/TiN_x multilayer films were deposited by magnetron sputtering, and the as-deposited multilayer coatings were annealed at 500-800 °C for 2-4 h in vacuum. We investigated the effects of annealing temperature and annealing time on the microstructural, interfacial, and mechanical properties of the polycrystalline Ti/TiN_x multilayer films. It was found that the hardness increased with annealing temperature. This hardness enhancement was probably caused by the preferred crystalline orientation TiN(1 1 1). The X-ray reflectivity measurements showed that the layer structure of the coatings could be maintained after annealing at 500 °C and the addition of the Si₃N₄ interlayer to Ti/TiN_x multilayer could improve the thermal stability to 800 °C.