Corrosion behavior of tantalum and its nitride in alkali solution

The corrosion behavior of tantalum and its nitrides in stirring NaOHsolutions was researched by potentiostatic method, cyclic voltammetry and XPS. The results showedthat the corrosion products were composed of Ta_2O_5 and NaTaO_3. The corrosion reaction formula oftantalum and its nitrides was written according to cyclic volt-ampere curves. The electric chargetransfer coefficient and the electric charge transfer number were calculated

Phase evolution of tantalum nitride and tantalum carbide films with PBII parameters

Tantalum nitride and tantalum carbide films were fabricated using magnetron sputtering of tantalum followed by nitrogen and carbon plasma-based ion implantation （N-PBII and C-PBII）. The phase evolution and morphology of the films were studied using glancing angle X-ray diffraction （GXRD） and transmission electron microscopy （TEM）. It was found that the main phase in the tantalum nitride films was crystalline TaNo.1 whose grain size increases with increasing implantation voltage and phase content increases with increasing implantation dose. In the tantalum carbide film, the main phase was Ta2C. TaC phase also appeared as the implantation dose increased. XRD results from various glancing angles show that the phases with high nitrogen or carbon content, Ta4N5 and TaC, are present in the surface of the films. X-ray photoelectron spectra （XPS） from the tantalum carbide film reveal that the surface carbon content is higher than that of the inner film.

Plasma-nitriding of tantalum at relatively low temperature

The combined quadratic orthogonal regression method of experiment design wasemployed to explore the effects of process parameters of plasma nitriding of tantalum such as totalpressure, temperature and original hydrogen molar fraction on the hardness, roughness and structureof nitriding surfaces. The regression equations of hardness, roughness and structure were givenaccording to the results of regression and statistic analysis. And the diffusion activation energyof nitrogen in tantalum on plasma nitriding conditions was calculated according to the experimentaldata of hardness of plasma-nitriding of tantalum vs time and temperature. The diffusion activationenergy calculated belongs to (155.49 +- 10.51) kJ/mol (783-983 K).

星用微波集成电路TaN薄膜电阻的功率耐受值研究

氮化钽(tantalum nitride,TaN)薄膜电阻电路是星载放大器、功分器等典型产品中必不可少的组成部分。在较大功率信号施加的条件下,TaN埋嵌电阻部位热效应较强,出现电路失效或烧毁的可能性也较其他部位大。星载微波单机应用环境条件恶劣,对于薄膜电阻的应用可靠性要求极高,常规侧重高温工况,热处理等条件下的氮化钽电阻功率耐受性研究无法得到实际星载应用工况中氮化钽电阻的功率特性,势必需要通过模拟实际应用工况和边界条件,通过设计制作氧化铝基板上不同尺寸TaN薄膜电阻样件,测量在施加不同电流的工况下电阻表面和电阻电极的温度,并根据电阻表面最大允许温升对应的电流,计算出可耐受的最大功率,完成了TaN薄膜电阻的功率耐受性研究。研究结果表明,在基板厚度一定时,随着电阻面积增大,薄膜电阻耐受功率呈增大趋势;较大尺寸薄膜电阻的功率耐受随着基板厚度的增加而降低。此研究结果对后续优化星用微波电路设计,提高宇航微波产品应用可靠性,减少不必要的设计冗余,有重要意义。

Engineering tantalum nitride for efficient photoelectrochemical water splitting

Photoelectrochemical(PEC)water splitting is a promising energy conversion strategy for directly converting solar energy into green hydrogen fuel.Constructing an efficient PEC device,finding an efficient photoanode material with a suitable band gap and favorable band-edge positions is essential.Tantalum nitride(Ta_(3)N_(5))meets these fundamental requirements,and its theoretical maximum solar-to-hydrogen(STH)conversion efficiency can reach 15.9%.Consequently,it has been widely applied as a photoanode material for the PEC oxygen evolution reaction(OER).However,severe bulk and interface charge recombination,along with sluggish water oxygen kinetics,seriously limits its STH conversion efficiency for PEC water splitting.Herein,this feature article briefly reviews recent advances by our research group in improving the STH conversion efficiency of the Ta_(3)N_(5)photoanode using various strategies,including defect engineering,construction of a gradient band structure,interface engineering,and surface modification of self-healing OER cocatalyst.Up to now,the obtained half-cell STH efficiency has exceeded 4%,providing a solid foundation for the development of tandem PEC devices for unbiased solar-driven overall water splitting toward practical application.

Metal-seed assistant photodeposition of platinum over Ta_(3)N_(5) photocatalyst for promoted solar hydrogen production under visible light

Cocatalysts play a vital role in accelerating the reaction kinetics and improving the charge separation of photocatalysts for solar hydrogen production.The promotion of the photocatalytic activity largely relies on the loading approach of the cocatalysts.Herein,we introduce a metal-seed assistant photodeposition approach to load the hydrogen evolution cocatalyst of platinum onto the surface of Ta_(3)N_(5) photocatalyst,which exhibits about 3.6 times of higher photocatalytic proton reduction activity with respect to the corresponding impregnation or photodeposition loading.Based on our characterizations,the increscent contact area of the cocatalyst/semiconductor interface with metal-seed assistant photodeposition method is proposed to be responsible for the promoted charge separation as well as enhanced photocatalytic H2 evolution activity.It is interesting to note that this innovative deposition strategy can be easily extended to loading of platinum cocatalyst with other noble or non-noble metal seeds for promoted activities,demonstrating its good generality.Our work may provide an alternative way of depositing cocatalyst for better photocatalytic performances.

高碘酸钾和双氧水对Cu,Ru和TaN去除速率影响的对比

Ru/TaN双分子层已经逐渐成为替代传统双分子阻挡层Ta/TaN的最佳选择,而在不同氧化体系中针对Cu,Ru和TaN三种金属去除速率的研究并不多。分别在H_2O_2和KIO_4两种氧化体系中,通过化学机械抛光（CMP）和电化学研究了Cu,Ru和TaN的去除速率及去除机理。测试结果表明：H_2O2和KIO_4均可以通过氧化Cu,Ru和TaN三种金属的表面从而提高三种材料的去除速率。不同的是,使用KIO_4作为氧化剂可以得到一个更高的Ru去除速率和更高的去除速率选择性,其原因为Ru在KIO_4溶液中更易于形成可溶的RuO_4^-和RuO_4^（2-）离子。此外,通过原子力显微镜（AFM）分别测试了Cu,Ru和TaN三种金属的表面粗糙度,结果表明：对比KIO_4,在H_2O_2抛光体系中Cu,Ru和TaN可以得到更好的表面质量。

Effects of TaN nanoparticles on microstructure,mechanical properties and tribological performance of PEEK coating prepared by electrophoretic deposition

In order to solve the friction,wear and lubrication problems of titanium,a series of TaN/ployether−ether−ketone(PEEK)coatings were developed by electrophoretic deposition,and the effects of TaN nanoparticles on the microstructure,mechanical properties and tribological performance of coatings were explored.Results manifest that the introduction of TaN nanoparticles into PEEK coatings could improve the deposition efficiency,enhance the resistant deform capacity,increase the hardness,elastic modulus and adhesive bonding strength.Compared with the pure PEEK coating,the friction coefficient of P-TN-3 was greatly reduced by 31.25%.The wear resistance of P-TN-3 was also improved in huge boost,and its specific wear rate was decreased from 9.42×10^(−5) to 1.62×10^(−5) mm^(3)·N^(−1)·m^(−1).The homogeneous composite TaN/PEEK coatings prepared by electrophoretic deposition were well-adhered to the titanium alloy substrate,TaN nanoparticles could improve the strength of PEEK coating,and provide wear-resistance protection for titanium alloys.

Valence electronic structure of tantalum carbide and nitride

The valence electronic structures of tantalum carbide (TaC) and tantalum nitride (TaN) are studied by using the empirical electronic theory (EET). The results reveal that the bonds of these compounds have covalent,metallic and ionic characters. For a quantitative analysis of the relative strength of these components,their ionicities have been calculated by implanting the results of EET to the PVL model. It has been found that the ionicity of tantalum carbide is smaller than that of tantalum nitride. The EET results also reveal that the covalent electronic number of the strongest bond in the former is larger than that of the latter. All these suggest that the covalent bond of TaC is stronger than that of TaN,which coincides to that de-duced from the first-principles method.

溅射制作埋嵌电阻的TaN薄膜电阻率的控制

文章介绍的是由射频(RF)溅射反应沉淀制备的TaN薄膜,以及在各种N2/Ar气流比例和工作压力下测试其电阻率变化。从X射线衍射(X-RD)图像和四点探针测试仪测试的TaNx薄膜方块电阻来看。研究发现,TaNx薄膜电阻率发生突变的原因主要是由于N2分压的作用而使TaNx薄膜晶体结构发生了变化。当六边形结构的TaN薄膜变成面心立方行结构时,薄膜电阻从16Ω/sq增加到1396Ω/sq。但是,在晶体结构不变和一定的工作压力范围内,我们能把TaN薄膜的电阻率控制在69Ω/sq到875Ω/sq范围内。在扫描电子显微镜(SEM)成像中,晶粒尺寸随着工作压力的增加将会有所减小。

Prediction of stable high-pressure structures of tantalum nitride TaN2

Structure searches based on a combination of first-principles calculations and a particle swarm optimization technique unravel two new stable high-pressure structures(C2/m and Cmce) for Ta N2. The structural features, mechanical properties, formation enthalpies, electronic structure, and phase diagram of Ta N2 are fully investigated. Being mechanically and dynamically stable, the two phases could be made metastable experimentally at ambient conditions.

微波电路用共面电极TaNx薄膜片式电阻器

采用反应溅射方法制作TaNx电阻薄膜,并通过溅射Ni、Au形成双层共面电极。研究了溅射条件对电阻薄膜组分的影响以及此类电阻器的微波特性。结果显示,溅射工作真空度小于0.5Pa,氮气体积分数大于5%时,可以得到阻值稳定的六方晶体结构TaNx电阻薄膜,其共面电极的电阻器使用频率上限大于20GHz。

IC互连金属及其阻挡层化学机械抛光的研究进展

集成电路的产业发展作为衡量一个国家经济实力的重要指标,反映该国的整体实力。在集成电路的众多制备工艺中,化学机械抛光(Chemical mechanical planarization,CMP)是关键制造技术之一,也是目前应用最广且能够实现全局和局部平坦化的技术。互连技术与CMP紧密相关,芯片互连属于后段制程,目前的互连技术主要包括铜互连、钴互连,在使用这些互连技术时不可避免地会影响芯片的性能,包括金属离子扩散速率快、薄膜与衬底的结合强度差等,学者们通过加入阻挡层来解决这些问题。互连金属和阻挡层都要进行CMP工序,它直接决定芯片良率和可靠性。本文总结了互连金属及其阻挡层化学机械抛光的研究进展,以技术节点出发介绍了三种典型的互连金属以及它们常用的阻挡层材料,分析总结了各种材料的抛光机理、抛光液组分、抛光效果及其材料的应用优势与缺陷,简述了在CMP互连与阻挡层的研究中存在的局限性,最后对新的材料、新型互连技术的研发及应用进行了展望。

钽等离子体渗氮的表面过程分析

对钽表面渗氮的固 气界面反应过程进行了热力学和动力学分析 ,从理论上预测了各种参数 (压力、气体组成、温度、电参数等 )对表面过程的影响 ,并借助于等离子体 ,在较低温度下获得了由表面层与N在Ta中的固溶体组成的表面硬化层。表面层为六方晶系的Ta6N2 ,57和 /或非晶态。通过调整工艺参数有效地抑制了钽表面氧的渗入和Ta2 O5 的形成 ,使得离子渗氮后 。

钽表面离子渗氮工艺研究

采用组合的二次回归正交设计方法 ,针对表面硬度、表面粗糙度 ,对钽表面离子渗氮工艺参数 (气体压力、温度、氢气摩尔分数 )进行了优化。

非平衡磁控溅射沉积Ta-N薄膜的结构与电学性能研究

采用直流反应非平衡磁控溅射技术在单晶Si（100）和玻璃表面沉积氮化钽（Ta-N）薄膜。分别测试了薄膜的结构、成分、电阻率和吸收光谱，研究了氯氩流量比（N2：Ar）变化对Ta—N薄膜的结构和电学性能的影响。研究结果表明随N2：Ar增加，依次生成六方结构的γ-Ta2N、面心立方结构（fcc）的δ-TaNx体心四方结构（bct）的TaNx；N2：Ar在0．2～0．8的范围内，Ta—N薄膜中只存在着fcc δ-TaNx；当N2：Ar〉1之后，Ta—N薄膜中fCC δ-TaN，和bct TaNx共存。Ta—N薄膜电阻率随N2：Ar流量比增加持续增加，当N2：Ar为1．2时，薄膜变为绝缘体，光学禁带宽度为1．51eV。

TiN基IrO_2-Ta_2O_5涂层析氢电极的催化性能

采用热分解法制备了以离子镀TiN膜为基体的IrO2-Ta2O5涂层电极,通过循环极化曲线并结合扫描电镜、X射线能谱和X射线衍射研究了涂层的析氢电催化性能.结果表明,涂层呈多孔多裂纹的结构,焙烧温度对涂层的表面形貌和电催化活性影响很大.420℃下焙烧的涂层具有最优的电催化活性.涂层电极的析氢反应电极电位为-0·26V(vsSCE),低析氢过电位下的Tafel斜率为-0·04V,而在高析氢过电位下,电极表面吸附的大量氢原子改变了氧化物电极的结构,从而抑制了氧的阴极还原反应.

钽表面渗氮层的氧化行为

进行了钽表面预先离子渗氮 对其后续表面高温熔盐阳极化过程及性能影响的试验研究。发现钽表面预先离子渗氮并不改变其后表面阳极化处理的动力学过程控制步骤，但表面膜层生长速度减慢。膜层物相由钽的氧化物变为氮化物。膜层静态电阻率增大；致密性更好。表面粗糙度降低，耐碱腐蚀性能提高。

氮化钽薄膜的制备及其血液相容性研究

本文利用磁控反应溅射技术制备氮化钽薄膜，对磁控反应溅射制备氮化钽薄膜的工艺参数（包括氮分压比、加热温度、溅射压力、溅射电流）用正交设计进行优化。研究表明，影响氮化钽薄膜结合力的主要因素为溅射压力和加热温度，氮分压比、溅射电流为次要因素；氮分压对氮化钽薄膜的硬度影响较大。动态凝血及血小板粘附实验研究表明，氮化钽薄膜的血液相容性性能优于热解碳（LTIC）。

热处理时间和压制密度对氮化钽粉电性能的影响

用均相钠还原得到的纳米氮化钽粉在1 350℃进行不同时间的热处理,热处理后的粉末制成烧结体并进行阳极氧化过程。通过XRD和场发射扫描电镜分析了粉末的物相结构和形貌,研究了热处理时间和压制密度对氮化钽粉末电性能的影响。结果表明:热处理温度为1 350℃、热处理时间40min、压制密度约4g/cm时氮化钽阳极块体有较高的比容和较低的漏电流常数。