The effect of nitrogen concentration on the properties of N-DLC prepared by helicon wave plasma chemical vapor deposition

Nitrogen-doped diamond-like carbon(N-DLC)films were synthesized by helicon wave plasma chemical vapor deposition(HWP-CVD).The mechanism of the plasma influence on the N-DLC structure and properties was revealed by the diagnosis of plasma.The effects of nitrogen doping on the mechanical and hydrophobicity properties of DLC films were studied.The change in the ratio of precursor gas flow reduces the concentration of film-forming groups,resulting in a decrease of growth rate with increasing nitrogen flow rate.The morphology and structure of N-DLC films were characterized by scanning probe microscopy,Raman spectroscopy,and X-ray photoemission spectroscopy.The mechanical properties and wettability of N-DLC were analyzed by an ultra-micro hardness tester and JC2000DM system.The results show that the content ratio of N^(+)and N_(2)^(+)is positively correlated with the mechanical properties and wettability of N-DLC films.The enhancement hardness and elastic modulus of N-DLC are attributed to the increase in sp3 carbon–nitrogen bond content in the film,reaching 26.5 GPa and 160 GPa respectively.Water contact measurement shows that the increase in the nitrogen-bond structure in N-DLC gives the film excellent hydrophobic properties,and the optimal water contact angle reaches 111.2°.It is shown that HWP technology has unique advantages in the modulation of functional nanomaterials.

Synthesis of SiC/graphene nanosheet composites by helicon wave plasma

We report an approach to the rapid, one-step, preparation of a variety of wide-bandgap silicon carbide/graphene nanosheet(Si C/GNSs) composites by using a high-density helicon wave plasma(HWP) source. The microstructure and morphology of the Si C/GNSs are characterized by using scanning electron microscopy(SEM), Raman spectroscopy, x-ray diffraction(XRD), x-ray photoelectron spectroscopy(XPS), and fluorescence(PL). The nucleation mechanism and the growth model are discussed. The existence of Si C and graphene structure are confirmed by XRD and Raman spectra.The electron excitation temperature is calculated by the intensity ratio method of optical emission spectroscopy. The main peak in the PL test is observed at 420 nm, with a corresponding bandgap of 2.95 e V that indicates the potential for broad application in blue light emission and ultraviolet light emission, field electron emission, and display devices.

Mechanism of high growth rate for diamond-like carbon films synthesized by helicon wave plasma chemical vapor deposition

A high growth rate fabrication of diamond-like carbon（DLC）films at room temperature was achieved by helicon wave plasma chemical vapor deposition（HWP-CVD）using Ar/CH4gas mixtures.The microstructure and morphology of the films were characterized by Raman spectroscopy and scanning electron microscopy.The diagnosis of plasma excited by a helicon wave was measured by optical emission spectroscopy and a Langmuir probe.The mechanism of high growth rate fabrication for DLC films by HWP-CVD has been discussed.The growth rate of the DLC films reaches a maximum value of 54μm h^-1at the CH4flow rate of 85 sccm,which is attributed to the higher plasma density during the helicon wave plasma discharge.The CH and Hαradicals play an important role in the growth of DLC films.The results show that the Hαradicals are beneficial to the formation and stabilization of C=C bond from sp^2to sp^3.

The properties of N-doped diamond-like carbon films prepared by helicon wave plasma chemical vapor deposition

In this paper, N-doped diamond-like carbon(DLC) films were deposited on silicon substrates by using helicon wave plasma chemical vapor deposition(HWP-CVD) with the Ar/CH_4/N_2 mixed gas. The surface morphology, structural and mechanical properties of the N-doped DLC films were investigated in detail by scanning electron microscopy(SEM), x-ray photoelectron spectroscopy(XPS), Raman spectra, and atomic force microscopy(AFM). It can be observed from SEM images that surface morphology of the films become compact and uniform due to the incorporation of N. The maximum of the deposition rate of the films is 143 nm min^(-1), which is related to the high plasma density. The results of XPS show that the N incorporates in the films and the C-C sp^3 bond content increases firstly up to the maximum(20%) at 10 sccm of N_2 flow rate, and then decreases with further increase in the N_2 flow rate. The maximum Young's modulus of the films is obtained by the doping of N and reaches 80 GPa at 10 sccm of N_2 flow rate, which is measured by AFM in the scanning probe microscope mode. Meanwhile, friction characteristic of the N-doped DLC films reaches a minimum value of 0.010.

Development of a helicon-wave excited plasma facility with high magnetic field for plasma-wall interactions studies

The high magnetic field helicon experiment system is a helicon wave plasma（HWP）source device in a high axial magnetic field（B0）developed for plasma–wall interactions studies for fusion reactors.This HWP was realized at low pressure（5×10^-3-10 Pa）and a RF（radio frequency,13.56 MHz）power（maximum power of 2 k W）using an internal right helical antenna（5 cm in diameter by 18 cm long）with a maximum B0of 6300 G.Ar HWP with electron density～10^18–10^20m^-3 and electron temperature～4–7 e V was produced at high B0 of 5100 G,with an RF power of 1500 W.Maximum Ar^＋ion flux of 7.8×10^23m^-2s^-1 with a bright blue core plasma was obtained at a high B0 of 2700 G and an RF power of 1500 W without bias.Plasma energy and mass spectrometer studies indicate that Ar^＋ ion-beams of 40.1 eV are formed,which are supersonic（～3.1cs）.The effect of Ar HWP discharge cleaning on the wall conditioning are investigated by using the mass spectrometry.And the consequent plasma parameters will result in favorable wall conditioning with a removal rate of 1.1×10^24N2/m^2 h.

Modification of exposure conditions by the magnetic field configuration in helicon antenna-excited helium plasma

Modification of exposure conditions downstream in the diffusion chamber has been performed in helicon antenna-excited helium plasma by adjusting the magnetic field(intensity and geometry).In the inductively coupled mode(H mode),a reduction in ion and heat fluxes is found with increasing magnetic field intensity,which is further explained by the more highly magnetized ions off-axis around the last magnetic field lines(LMFL).However,in helicon wave mode(W mode),the increase in magnetic field intensity can dramatically increase the ion and heat fluxes.Moreover,the effect of LMFL geometry on exposure conditions is investigated.In H mode with contracting LMFL,off-axis peaks of both plasma density and electron temperature profiles shift radially inwards,bringing about a beam with better radial uniformity and higher ion and heat fluxes.In W mode,although higher ion and heat fluxes can be achieved with suppressed plasma cross-field diffusion under converging LMFL,the poor radial uniformity and a small beam diameter will limit the size of samples suitable for plasma irradiation experiments.

The application of a helicon plasma source in reactive sputter deposition of tungsten nitride thin films

A reactive helicon wave plasma(HWP)sputtering method is used for the deposition of tungsten nitride(WNx)thin films.N_(2)is introduced downstream in the diffusion chamber.The impacts of N_(2)on the Ar-HWP parameters,such as ion energy distribution functions(IEDFs),electron energy probability functions(EEPFs),electron temperature(Te)and density(ne),are investigated.With the addition of N_(2),a decrease in electron density is observed due to the dissociative recombination of electrons with N_(2)^(+).The similar IEDF curves of Ar+and N_(2)^(+) indicate that the majority ofN_(2)^(+) stems from the charge transfer in the collision between Ar+and N_(2).Moreover,due to the collisions between electrons and N_(2)ions,EEPFs show a relatively lower Tewith a depletion in the high-energy tail.With increasing negative bias from 50 to 200 V,a phase transition from hexagonal WN to fcc-WN0.5is observed,together with an increase in the deposition rate and roughness.

高密度螺旋波等离子体源的应用进展

首先介绍了螺旋波的定义、螺旋波等离子体源产生等离子体所需条件的工作范围以及螺旋波等离子体源主要的一些应用。按照所加磁场范围的不同(分为在磁感应强度为100～1 600Gs和在强磁场中两部分),分别进一步讨论了国内外各研究小组研制的等离子体源的运行参数及技术特点。随后介绍了螺旋波等离子体源在刻蚀、薄膜沉积和火箭推进三个方面的应用进展。其中重点介绍了螺旋波等离子体火箭推进。最后简单展望了螺旋波等离子体源的应用前景,并指出其发展中尚待解决的一些问题。

低温低压氢等离子体的光谱分析

采用螺旋波激发氢等离子体,测得氢的Balmer线系前三条谱线的强度。利用二谱线法求电子温度Te,并由Hβ的Stark展宽得到电子密度Ne,简要分析了Te、Ne以及强度与各种参数之间的关系。

HWP-CVD氮化硅薄膜的结构和光学特性

采用傅立叶红外吸收谱和紫外-可见透射谱研究了螺旋波等离子体增强化学气相沉积法制备的氢化非晶氮化硅薄膜的原子间键合结构和光学特性。结果表明,在不同硅、氮活性气体配比冗下,薄膜表现出不同的Si/N比和H原子键合方式,富氮样品中H原子主要和N原子结合,而富硅样品中主要和Si原子结合。随着R的增加,薄膜的光学带隙Eg和E04逐渐减小,此结果关联于薄膜结构无序性程度的增加,而薄膜的(E04-Eg)和Tauc斜率B值之间存在着相互制约关系。

氢化非晶氮化硅薄膜的光学特性研究

采用螺旋波等离子体增强化学气相沉积 (HWP -CVD)技术以SiH4 和N2 为反应气体沉积了氮化硅 (SiN)薄膜 ,利用傅里叶红外吸收谱 (FTIR)、紫外 -可见透射谱 (UV -VIS)等对薄膜的键合结构、光学带隙等参量进行了测量与分析 .结果表明 ,采用HWP -CVD技术能在较低的衬底温度下制备低H含量的SiN薄膜 ,所沉积的薄膜主要表现为Si -N键合结构 .适当提高N2 /SiH4 比例将有利于薄膜中H含量的降低 .

螺旋波等离子体化学气相沉积法制备纳米碳化硅薄膜

采用螺旋波等离子体化学气相沉积 (HWP CVD)技术在Si(10 0 )和石英衬底上合成了具有纳米结构的碳化硅薄膜。通过X射线衍射 (XRD)、傅立叶红外透射 (FTIR)和原子力显微镜 (AFM)等技术对所制备薄膜的结构、组分和形貌进行了分析 ,利用光致发光技术研究了样品的发光特性。分析表明 ,在 70 0℃的衬底温度和 1.33Pa的气压条件下所制备纳米SiC薄膜的平均颗粒度在 3nm以下 ,红外透射谱主要表现为Si C吸收。结果说明HWP CVD为制备高质量纳米SiC薄膜的有效技术 ,所制备样品呈现出室温短波长可见发光特性 ,发光谱主峰位于 395nm附近。

不同衬底温度下ZnO外延薄膜的结构及光学特性分析

采用螺旋波等离子体辅助射频溅射沉积技术在A l2O3(0001)衬底上沉积ZnO外延薄膜,通过对其结构及光学性质的分析,探讨了衬底温度对薄膜生长特性的影响。实验结果表明,由于等离子体对反应气体的活化及载能粒子对表面反应的辅助作用,采用该等离子体辅助溅射技术能够在较低的衬底温度下实现较高质量的ZnO薄膜外延生长,然而,较高的衬底温度所引起的表面反应不利于薄膜中的氧空位及锌填隙等缺陷的减少,这将限制薄膜的外延质量及光学特性的进一步提高。

应用于超大规模集成电路工艺的高密度等离子体源研究进展

本文简要地介绍了等离子体的产生方式以及传统的射频电容耦合等离子体源。对电子回旋共振等离子体(ECR) ,感应耦合等离子体 (ICP) ,螺旋波等离子体 (HWP)等几种新型的高密度等离子体源[1] 的工作原理及结构重点作了分析讨论 ,并从运行参数上对其进行了比较。

径向压力和温度分布对螺旋波等离子体波场和能量吸收影响研究

为了揭示螺旋波等离子体推力器中的等离子体源功率耦合机理,针对气体工质电离后被射频加热的稳态过程,考虑等离子体密度非均匀分布条件,采用三参数压力函数(fa,sp,tp)和温度函数(f_a,s_t,t_t)表示柱状等离子体内压力和温度的径向分布,分析了径向压力梯度、温度梯度对螺旋波等离子体内功率沉积、波电场、波磁场和电流密度的影响。考虑梯度为正,梯度为负和梯度为零三种梯度类型。结果发现:压力梯度为正时,螺旋波在等离子体临近壁面处的功率沉积减弱,但射频波透入深度增加,原因是靠近管壁处等离子体密度较低,RF波径向单位长度衰减较少,透入深度增加。温度梯度为负时,柱状等离子体中心处能量沉积变强,原因是管中心位置等离子体密度较大,电子温度较高,与RF波能量耦合增强;横向截面的电磁场、电流密度分布在不同压力和温度梯度下基本不变,证明了m=1模式的稳定性。

朗谬尔单探针测量螺旋波等离子体参量

在国内首次引入了一种用朗谬尔单探针测量螺旋波等离子体参数的简单方法,并阐述了测量原理,对实验结果进行了初步的讨论.结果表明测量螺旋波等离子体参量的朗谬尔单探针法简单可行,是一种较好的测量手段.

氧分压对Zno薄膜结构、光学和电学特性的影响

采用螺旋波等离子体辅助射频溅射技术在Al203衬底的(0001)面上制备了ZnO薄膜.通过对其结构,光学及电学性质的分析,探讨了氧分压对薄膜生长及其特性的影响.结果表明,由于等离子体对反应气体的活化及载能粒子对表面反应的辅助作用,采用该等离子体辅助溅射技术能够在合适的氧分压下制得较高质量的ZnO薄膜.

等离子体微细加工技术的新进展

在大规模集成电路制造中常用反应离子刻蚀 ,但对于加工 2 0 0mm以上直径的片子和 0 2 5 μm的线宽及孔洞 ,它的能力已达到极限。低压等离子刻蚀设备 (ECR ,ICP ,HWP)和高浓度等离子体可以解决这一问题。已经在整个片子上均匀地获得高的刻蚀速率。剖面控制精确 ,可改善图形的保真度。本文介绍了干法刻蚀技术的这一最新进展 ,阐述了电子回旋共振等离子体源、感应耦合等离子体源、螺旋波等离子体源的工作原理和干法刻蚀的关键技术问题。

螺旋波激发氢等离子体的电子温度及密度研究

采用射频调谐朗缪尔单探针方法对螺旋波激发的氢等离子体I-V特性曲线进行了测量。运用Druyvestey方法对氢等离子体的电子能量分布(EEDF)及电子密度ne的变化规律进行了研究,并与发射光谱诊断结果进行了比较。结果表明:ne随着射频功率的增大成线性增大,本实验中最大值可达到1012cm-3量级,电子平均能量E随着射频功率的增大逐渐升高,并逐渐达到饱和;ne随着工作气压的增加而增大并出现峰值,存在一个最佳气压范围(2 Pa^4 Pa)使ne达到最大,E则随着工作气压的增加逐渐减小;氢气流量对ne的影响非常小,当氢气流量达到一定值(12 sccm)后,ne几乎不变化,E随着氢气流量的增加逐渐降低,最后趋于稳定;朗缪尔单探针方法与发射光谱法诊断的结果基本一致。

等离子体径向压力分布对射频波功率吸收影响

为建立高效稳定的螺旋波等离子体源,提高离子风暴发动机推进效率,需要对射频波在等离子体中的能量耦合机理进行研究。基于气体工质电离后被射频加热的稳态过程,在管中等离子体密度呈抛物线分布条件下,研究了等离子体对Nagoya III型射频天线激发出的射频波功率吸收情况。运用Helic程序对应每个轴向波数kz求解管内电磁场相关的4个径向耦合微分方程,得到能量吸收、波电磁场和电流密度沿不同方向分布情况。通过分析不同压力构型对螺旋波等离子体内能量沉积、波电磁场和电流密度的影响,结果发现:正压力梯度下,射频波透入等离子体径向距离增加,但功率沉积减少,波磁场强度沿各向分量均有所增大。压力梯度的存在使得波电场和电流密度在管壁附近显著增大。