Structure and mechanical properties of Mo-N/Cu films produced by inductively coupled plasma reactive sputtering

Mo-N/Cu films were deposited on silicon and steel substrates by inductively coupled plasma sputtering using Mo-Cu alloy targets having different Cu concentrations. The structure and mechanical properties of the Mo-N/Cu films were investigated. The (200)-oriented γ-Mo₂N-Cu films were obtained at a nitrogen flow rate higher than 1.5 sccm, whereas metallic films were deposited at a nitrogen flow rate lower than 1 sccm. Cu contents in the films increased from 3 at.% to 8 at.% with corresponding increase in Cu concentrations in the target from 5 at.% to 20 at.%. Hardness of the films varied between 19 and 35 GPa as the Cu concentration and nitrogen flow rate were changed. HRTEM and XPS analyses showed that Mo-N/Cu films consisted of γ-Mo₂N grains lower than 10 nm in size and a copper amorphous phase. The minimum value of coefficient of friction (CoF) of the films was 0.17 when the film tested by alumina ball.     

Study of the inductively coupled plasma assisted DC magnetron sputtering (ICPDMS) during ITO deposition

An inductively coupled plasma (ICP) assisted DC magnetron sputtering (ICPDMS) method for the deposition of indium tin oxide (ITO) thin films was developed to satisfy the challenging requirements of a room temperature process and high temperature durability. The resistivity of ITO thin films deposited by ICPDMS at room temperature was improved to as low as 1.2 × 10^− 2 Ω cm by increasing the RF power of the ICP source to 1200 W. Due to the additional dissociation and ionization by the high density plasma in ICPDMS system, the ITO thin films have a higher portion of Sn and oxygen atoms and a lower initial carrier concentration, ~ 10¹⁸ #/cm³, at room temperature than conventional ITO. However, the carrier concentration could be rapidly increased up to 10²⁰ #/cm³ by post-annealing to temperatures as high as 500 °C for 1 h under high vacuum conditions. Unlike conventional ITO, the electrical properties of ICPDMS-ITO were relatively unchanged after high temperature heat cycles, which is a very attractive property for high performance photovoltaic solar cell applications.     

Dry etching of magnesium oxide thin films by using inductively coupled plasma for buffer layer of MFIS structure

Magnesium oxide thin film has been widely used as a buffer layer and substrate for growing various thin film materials because of very low Gibbs free energy, low dielectric constant and low refractive index. The investigations of the MgO etching characteristics in BCl₃/Ar plasma were carried out using the inductively coupled plasma system. It was found that the increasing BCl₃ in the mixing ratio of BCl₃/Ar plasma causes monotonic MgO etch rate. The results showed in the BCl₃-rich plasma that the etching process is dominantly supplied by the chemical pathway through the ion-assisted chemical reaction.     

Etch characteristics of FePt magnetic thin films using inductively coupled plasma reactive ion etching

Etch characteristics of L10 FePt thin films masked with TiN films were investigated using an inductively coupled plasma (ICP) reactive ion etching in a CH₃OH/Ar plasma. As the CH₃OH gas was added to Ar, the etch rates of FePt thin films and TiN hard mask gradually decreased, and the etch profile of FePt films improved with high degree of anisotropy. With increasing ICP rf power and dc-bias voltage to substrate and decreasing gas pressure, the etch rate increased and the etch profile becomes vertical without any redepositions or etch residues. Based on the etch characteristics and surface analysis of the films by X-ray photoelectron spectroscopy, it can be concluded that the etch mechanism of FePt thin films in a CH₃OH/Ar gas does not follow the reactive ion etch mechanism but the chemically assisted sputter etching mechanism, due to the chemical reaction of FePt film with CH₃OH gas.     

Time evolution of electronegativity in a pulsed inductively coupled oxygen plasma

The electronegativity in a continuous wave (CW) and pulsed mode plasmas was calculated using the measured results of both the single Langmuir probe and the retarding field analyzer. For the pulsed mode measurement, both of the measurements were performed in a time-resolved method using a boxcar sampling technique. For the conversion of the retarding field analyzer measurement results into absolute positive ion densities, argon plasma was used as a reference. The pulsed oxygen plasma was generated using the inductively coupled antenna and modulated at a repetition rate of 5 kHz and the duty ratio of 50%. The gas pressure was changed from 5 to 30 mTorr. The time evolution of the electronegativity shows that there is a pressure regime where the electron attachment reaction during the RF on-time is very active, indicating that the negative ion density reaches its maximum value during the RF on-time. Compared to the CW oxygen plasma, the electronegativity of the pulsed oxygen plasma varies within a wider range of values.     

Low temperature deposition of tin oxide films by inductively coupled plasma assisted chemical vapor deposition

Well-crystallized tin oxide films were successfully synthesized without additional heating by inductively coupled plasma assisted chemical vapor deposition (ICP-CVD). The degree of crystallization was affected by the ICP power and hydrogen flow rate. The substrate temperature was increased only up to 423-453 K by plasma heating, which suggests that the formation of the SnO₂ crystals was not caused by plasma heating, but by enhanced reactivity of precursors in high density plasma. The micro-hardness of deposited tin oxide films ranged from 5.5 to 11 GPa at different hydrogen flow rates.     

磁控溅射非晶CNx薄膜的热稳定性研究

为了研究非晶CNx薄膜的热稳定性,采用射频磁控溅射方法沉积了非晶CNx薄膜样品,并在真空中退火至900℃,利用FTIR,Raman和XPS谱探讨了高温退火对CNx薄膜化学成分及键合结构的影响.研究表明:CNx薄膜样品中N原子分别与sp、sp2和sp3杂化状态的C原子相结合,退火处理极大地影响了CN键合结构的稳定性;当退火温度低于600℃时,膜内N含量的损失较少,CNx薄膜的热稳定性较好,退火温度超过600℃时,将导致CNx膜中大多数C、N间的键合分离,造成N大量损失,膜的热稳定性下降;退火可促使膜内sp3型键向sp2型键转变,在膜中形成大量的sp2型C键,导致CNx膜的石墨化.     

潘宁放电溅射沉积纳米级AlN薄膜的性质

设计并制造了新的潘宁型等离子体源实验装置，分析了等离子体的发射光谱和产生AIN的动力学机理。在室温条件下，纯氮气的工作环境中用潘宁放电离子源溅射的方法，在Si（100）衬底上制备了纳米级的光滑平整AIN薄膜。本文用扫描电镜（SEM），原子力显微镜（ATM），红外吸收光谱（FTIR）和拉曼光谱（Raman shift）等测试分析技术用来研究了薄膜的微结构特征。     

采用MCECR等离子体溅射方法制备硬碳膜

采用封闭式电子回旋共振(MCECR)等离子体溅射的方法在硅(100)基片上沉积了高质量的硬碳纳米微晶薄膜,膜层厚度约40 nm,采用氩等离子体溅射碳靶.薄膜的键结构采用X射线光电子能谱仪(XPS)分析,纳米结构采用高分辨率透射电子显微镜(HRTEM)分析.本文研究了基片偏压对薄膜的纳米结构、摩擦特性(摩擦系数及磨损率)以及薄膜的纳米硬度的影响.摩擦特性采用POD摩擦磨损仪测试,纳米硬度采用纳米压入仪测试.     

CVD of hard DLC films in a radio frequency inductively coupled plasma source

Chemical vapor deposition (CVD) of hard diamond-like carbon (DLC) films on silicon (100) substrates from methane was successfully carried out using a radio frequency (r.f.) inductively coupled plasma source (ICPS). Different deposition parameters such as bias voltage, r.f. power, gas flow and pressure were involved. The structures of the films were characterized by Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. The hardness of the DLC films was measured by a Knoop microhardness tester. The surface morphology of the films was characterized by atomic force microscope (AFM) and the surface roughness (R_a) was derived from the AFM data. The films are smooth with roughness less than 1.007 nm. Raman spectra shows that the films have typical diamond-like characteristics with a D line peak at 1331 cm⁻¹ and a G line peak at 1544 cm⁻¹, and the low intensity ratio of I_D/I_G indicate that the DLC films have a high ratio of sp³ to sp² bonding, which is also in accordance with the results of FTIR spectra. The films hardness can reach approximately 42 GPa at a comparatively low substrate bias voltage, which is much greater than that of DLC films deposited in a conventional r.f. capacitively coupled parallel-plate system. It is suggested that the high plasma density and the suitable deposition environment (such as the amount and ratio of hydrocarbon radicals to atomic or ionic hydrogen) obtained in the ICPS are important for depositing hard and high quality DLC films.     

The dry etching property of TiO2 thin films using metal-insulator-metal capacitor in inductively coupled plasma system

In this work, we investigated the etching characteristics of TiO₂ thin films and the selectivity of TiO₂ to SiO₂ in a BCl₃/Ar inductively coupled plasma (ICP) system. The maximum etch rate of 84.68 nm/min was obtained for TiO₂ thin films at a gas mixture ratio of BCl₃/Ar (25:75%). In addition, etch rates were measured as a function of etching parameters, such as the RF power, DC-bias voltage and process pressure. Using the X-ray photoelectron spectroscopy analysis the accumulation of chemical reaction on the etched surface was investigated. Based on these data, the ion-assisted physical sputtering was proposed as the main etch mechanism for the BCl₃-containing plasmas.     

射频磁控溅射制备硼碳氮薄膜

采用射频磁控溅射技术,用六角氮化硼和石墨为溅射靶,以氩气(Ar)和氮气(N2)为工作气体,在Si (100)衬底上制备出硼碳氮薄膜.通过X射线衍射(XRD)、傅里叶红外吸收光谱(FTIR)和X射线光电子能谱(XPS)等分析手段对样品结构、组分进行了分析.结果表明,样品的组成原子之间实现了原子级化合,且薄膜为乱层石墨结构.样品中B、C、N的原子比近似为1:1:1.     

Solid-phase extraction of Cu, Co and Pb on oxidized single-walled carbon nanotubes and their determination by inductively coupled plasma mass spectrometry

A novel method using a microcolumn packed with single-walled carbon nanotubes (SWNTs) as a new adsorption material was developed for the preconcentration of trace Cu, Co and Pb in biological and environmental samples prior to their determination by inductively coupled plasma mass spectrometry (ICP-MS). SWNTs oxidized with concentrated nitric acid have been proved to possess an exceptional adsorption capability for the analytes due to their surface functionalization. The adsorption behaviors of the analytes on SWNTs under dynamic conditions were studied systematically. The main factors influencing the preconcentration and determination of the analytes (pH, sample flow rate and volume, eluent concentration and interfering ions) have been examined in detail. Under the optimum conditions, the detection limits for Cu, Co and Pb were 39, 1.2 and 5.4 pg mL⁻¹, respectively; the relative standard deviations (RSDs) were found to be less than 6.0% (n = 9, c = 1.0 ng mL⁻¹). This method was validated using a certified reference material of mussel, and has been successfully applied for the determination of trace Cu, Co and Pb in real water sample with the recoveries of 96.0–109%.     

Electron-emission properties of carbon nanotube micro-tips coated by amorphous carbon nitride films

An approach to the preparation of a tip-type of field emitter that is made up of carbon nanotubes (CNTs) coated with amorphous carbon nitride (a-CN_x) films is presented for the purpose of enhancing its electron emission property. CNTs were directly grown on nano-sized conical-type tungsten tips via the inductively coupled plasma-chemical vapor deposition system, and a-CN_x films were coated on the CNTs using an radio frequency magnetron sputtering system. The morphologies and microstructures of the a-CN_x-coated CNTs were analyzed via field emission scanning electron microscopy, energy-dispersive x-ray spectroscopy, high-resolution transmission electron microscopy, and x-ray photoelectron spectroscopy. The electron emission properties of the a-CN_x/CNT hetero-structures were measured using a high-vacuum field emission measurement system. The best field emission properties, such as a very low turn-on voltage of 500 V and a maximum emission current of 176 μA were achieved for the CNT emitter coated with the 5 nm-thick a-CN_x film. In addition, this emitter showed a highly stable behavior in long-term (up to 25 h) electron emission.     

Optimization of ion energy spread in inductively coupled plasma source designed for focused ion beam applications

The ion energy distribution of inductively coupled plasma ion source for focused ion beam application is measured using a four grid retarding field energy analyzer. Without using any Faraday shield, ion energy spread is found to be 50 eV or more. Moreover, the ion energy distribution is found to have double peaks showing that the power coupling to the plasma is not purely inductive, but a strong parasitic capacitive coupling is also present. By optimizing the various source parameters and Faraday shield, ion energy distribution having a single peak, well separated from zero energy and with ion energy spread of 4 eV is achieved. A novel plasma chamber, with proper Faraday shield is designed to ignite the plasma at low RF powers which otherwise would require 300-400 W of RF power. Optimization of various parameters of the ion source to achieve ions with very low energy spread and the experimental results are presented in this article.     

氮化碳薄膜的电化学沉积及其电阻率研究

在ITO导电玻璃基底上,采用二氰二胺分散在DMF(N,N-二甲基甲酰胺)中形成的溶液做沉积液,阴极电化学沉积了CNx薄膜。X射线光电子能谱(XPS)和傅立叶转换红外光谱(FTIR)的分析结果表明,沉积的CNx薄膜的N/C比为0.7左右,碳和氮主要以C-N、C=N的形式成键,有少量的碳和氮以C≡N的形式成键。拉曼光谱测试发现其存在多个吸收峰,对其进行分析的结果表明薄膜样品中含有α-C3N4和β-C3N4相的成分。电阻率测试表明,氮化碳薄膜的电阻率值达到1012～1013Ω·cm。     

Etch characteristics of IrMn thin films using an inductively coupled plasma of CH3OH/Ar

An inductively coupled plasma reactive ion etching of IrMn magnetic thin films patterned with Ti hard mask was studied in a CH₃OH/Ar gas mix. As the CH₃OH concentration increased, the etch rates of IrMn thin films and Ti hard mask decreased, while the etch profiles improved with high degree of anisotropy. The effects of coil rf power, dc-bias voltage to substrate and gas pressure on the etch characteristics were investigated. The etch rate increased and the etch profile improved with increasing coil rf power, dc-bias voltage and decreasing gas pressure. X-ray photoelectron spectroscopy revealed that the chemical reaction between IrMn films and CH₃OH gas occurred, leading to the clean and good etch profile with high degree of anisotropy of 90°.     

Mechanical properties optimization of tungsten nitride thin films grown by reactive sputtering and laser ablation

Transition metal nitrides coatings are used as protective coatings against wear and corrosion. Their mechanical properties can be tailored by tuning the nitrogen content during film synthesis. The relationship between thin film preparation conditions and mechanical properties for tungsten nitride films is not as well understood as other transition metal nitrides, like titanium nitride. We report the synthesis of tungsten nitride films grown by reactive sputtering and laser ablation in the ambient of N₂ or N₂/Ar mixture at various pressures on stainless steel substrates at 400  C. The composition of the films was determined by XPS. The optimal mechanical properties were found by nanoindentation based on the determination of the proper deposition conditions. As nitrogen pressure was increased during processing, the stoichiometry and hardness changed from W₉N to W₄N and 30.8-38.7 GPa, respectively, for films deposited by reactive sputtering, and from W₆N to W₂N and 19.5-27.7 GPa, respectively, for those deposited by laser ablation.     

Growth of VO2 films with metal-insulator transition on silicon substrates in inductively coupled plasma-assisted sputtering

Single-phase monoclinic vanadium dioxide (VO₂) films were grown on a Si(100) substrate using inductively coupled plasma (ICP)-assisted sputtering with an internal coil. The VO₂ film exhibited metal-insulator (M-I) transition at around 65 °C with three orders of change in resistivity, with a minimum hysteresis width of 2.2 °C. X-ray diffraction showed structural phase transition (SPT) from monoclinic to tetragonal rutile VO₂. For conventional reactive magnetron sputtering, vanadium oxides with excess oxygen (V₂O₅ and V₃O₇) could not be eliminated from stoichiometric VO₂. Single-phase monoclinic VO₂ growths that are densely filled with smaller crystal grains are important for achieving M-I transition with abrupt resistivity change.     

Electrochemical corrosion behavior of amorphous carbon nitride thin films

The corrosion behavior along with biocompatibility and mechanical properties plays an important role in determining of biomedical implants feasibility. Diamond-like carbon seems to be the promising material in which all these three requirements can be achieved. In this study nitrogen doped amorphous carbon (a-C:N) films were deposited on silicon and medical CoCrMo alloy substrates by vacuum glow discharge sputtering technique using different deposition conditions from graphite target. Potentiodynamic polarization tests were employed to assess the corrosion performances of the films at room temperature in 0.89 wt. % NaCl solution. The influence of substrate bias on the electrochemical corrosion behavior was investigated. The highest value off E_corr for CoCrMo substrate was measured on the coating deposited with substrate bias around −0.6 kV. The shift of E_corr to more positive values was about 350 mV.