Effect of Frequency and Power of Bias Applied to Substrate on Plasma Property of Very-High-Frequency Magnetron Sputtering

The effect of the frequency and power of the bias applied to the substrate on plasma properties in 60 MHz(VHF) magnetron sputtering was investigated.The plasma properties include the ion velocity distribution function(IVDF),electron energy probability function(EEPF),electron density n_e,ion flux Γ_i,and effective electron temperature T_(eff).These parameters were measured by a retarding field energy analyzer and a Langmuir probe in the 60 MHz magnetron sputtering,assisted with 13.56 MHz or 27.12 MHz substrate bias.The 13.56 MHz substrate bias led to broadening and multi-peaks IVDFs,Maxwellian EEPFs,as well as high electron density,ion flux,and low electron temperature.The 27.12 MHz substrate bias led to a further increase of electron density and ion flux,but made the IVDFs narrow.Therefore,the frequency of the substrate bias was a possible way to control the plasma properties in VHF magnetron sputtering.     

Diagnosing the Fine Structure of Electron Energy Within the ECRIT Ion Source

The ion source of the electron cyclotron resonance ion thruster(ECRIT) extracts ions from its ECR plasma to generate thrust, and has the property of low gas consumption(2 sccm,standard-state cubic centimeter per minute) and high durability. Due to the indispensable effects of the primary electron in gas discharge, it is important to experimentally clarify the electron energy structure within the ion source of the ECRIT through analyzing the electron energy distribution function(EEDF) of the plasma inside the thruster. In this article the Langmuir probe diagnosing method was used to diagnose the EEDF, from which the effective electron temperature, plasma density and the electron energy probability function(EEPF) were deduced. The experimental results show that the magnetic field influences the curves of EEDF and EEPF and make the effective plasma parameter nonuniform. The diagnosed electron temperature and density from sample points increased from 4 eV/2×10~(16)m~(-3) to 10 eV/4×10~(16)m(-3) with increasing distances from both the axis and the screen grid of the ion source. Electron temperature and density peaking near the wall coincided with the discharge process. However, a double Maxwellian electron distribution was unexpectedly observed at the position near the axis of the ion source and about 30 mm from the screen grid. Besides, the double Maxwellian electron distribution was more likely to emerge at high power and a low gas flow rate. These phenomena were believed to relate to the arrangements of the gas inlets and the magnetic field where the double Maxwellian electron distribution exits. The results of this research may enhance the understanding of the plasma generation process in the ion source of this type and help to improve its performance.     

高能碰撞中的多重数分布与动力学涨落

通过多重数分布研究EMU01国际实验组中高能重核束流与微乳胶相互作用中的动力学起伏的规律。引入多重数分布动力学因子dq及其比值Dq两个物理量来定量量度动力学涨落,得到了Dq与D2的幂次标度律,并且给出标度律中指数与q-1的标度关系,所得出的标度指数γ的值在各种碰撞体系中大致相同。     

Energy properties and spatial plume profile of ionic liquid ion sources based on an array of porous metal strips

An ionic liquid ion source(ILIS)is a kind of high brightness ion source capable of providing high-speed positive or negative ion beams.This paper presents a miniaturized ILIS based on an array of porous metal strips.The porous emitter array,integrated with seven 10 mm long strips,is fabricated using wire electrical discharge machining(WEDM)combined with electrochemical etching.The assembled ILIS is 30 mm x 30 mm x 17.5 mm in size and weighs less than 25 g.A series of experiments,including an I-V characteristic test,a retarding potential analyzer(RPA)test,and a spatial plume distribution test,have been conducted in vacuo to characterize the performance of the ILIS.Results show that the emitted current is up to about 800 μA and ion transparency is as high as 94％.Besides,RPA curves reveal that the total fragmentation rate of the emitted particles accounts for 48.8％in positive mode and 59.8％in negative mode.Further,with the increase in applied acceleration voltage,the voltage loss rises while the energy efficiency decreases.It is also found that the plume perpendicular to the strips has a higher divergence than the one parallel to the strips.A numerical simulation by COMSOL reveals that the electric field distribution between the two electrodes results in such a spatial plume profile.     

Computer-Controlled System for Plasma Ion Energy Auto-Analyzer

A computer-controlled system for plasma ion energy auto-analyzer was technically studied for rapid and online measurement of plasma ion energy distribution. The system intelligently controls all the equipments via a RS-232 port, a printer port and a home-built circuit. The software designed by LabVIEW G language automatically fulfils all of the tasks such as system initializing, adjustment of scanning-voltage, measurement of weak-current, data processing, graphic export, etc. By using the system, a few minutes are taken to acquire the whole ion energy distribution, which rapidly provides important parameters of plasma process techniques based on semiconductor devices and microelectronics.     

Dynamic energy spectrum and energy deposition in solid target by intense pulsed ion beams

A method for analyzing the dynamic energy spectrum of intense pulsed ion beam (IPIB) was proposed.Its influence on beam energy deposition in metal target was studied with IPIB produced by two types of magnetically insulated diodes (MID).The emission of IPIB was described with space charge limitation model,and the dynamic energy spectrum was further analyzed with time-of-flight method.IPIBs generated by pulsed accelerators of BIPPAB-450 (active MID) and TEMP-4M (passive MID) were studied.The dynamic energy spectrum was used to deduce the power density distribution of IPIB in the target with Monte Carlo simulation and infrared imaging diagnostics.The effect on the distribution and evolution of thermal field induced by the characteristics of IPIB dynamic energy spectrum was discussed.     

Power Law Distributions in the Experiment for Adjustment of the Ion Source of the NBI System

1 Introduction Power law distribution is widely observed in nature. In the early years, power law distribution was studied by G. K. Zipf in words' frequency distribution of human language [1]. It shows that, if arranging the frequencies of words with a decay rank, the relationship between the frequencies and the ranks of the words correspond to the power law as follows where, P(r) is the word frequency, and r is the rank of the word. α is usually called Zipf's exponential or power exponenti…     

COMPOSITIONAL ANALYSIS OF HIGH-TEMPERATURE SUPERCONDUCTOR THIN FILMS BY HIGH ENERGY ELASTIC BACKSCATTERING OF HELIUM IONS

High energy ion backscattering can be used to enhance the sensitivity of oxygen analysis. At He++ ion energy of 8.8 MeV, the yield due to oxygen is about 25 times larger than that predicted by Rutherford formula. The elemental stoichiometry of some bulk and thin film superconductor samples was determined. The details of the measuring method are discribed.     

Evaluation of NBI absorption and fast ion stored energy to improve thermal energy confinement time calculation in EAST

The absorption of neutral beam power and the fast ion stored energy in EAST plasmas with neutral beam injection(NBI)is analyzed to improve the calculation of thermal energy confinement time.The neutral beam power absorption and fast ion stored energy are systematically calculated using the TRANSP code,through the investigation of global parameters including plasma current,line averaged density and beam energy.Results have shown that scaling laws for the NBI absorption coefficient and fast ion energy rate are obtained through statistical analysis.A comparison of the confinement improvement factor H98y2 with these new scaling laws against those assuming fixed coefficients is given.     

Improvement of the Energy Stability of the Single Ion Microbeam

Energy instability strongly affects the state and the beam size of the single ion microbeam. A facility based on the Generating Voltmeter was developed to improve the energy stability of the CAS-LIBB （Chinese Academy of Sciences, key laboratory of ion beam bioengineering） single ion microbeam. This paper presents the analysis of the energy＇ instability of the single ion microbeam. A simplified theoretical model is set up to calculate the relationship between the energy instability and the beam spot size. By using this technique, the energy instability is adjusted to about 1%. Stable run-time is over 6 hours. The radius of the single ion beam is reduced by 10% compared to the previous olin.     

离子初始能量及其对二极管空间电荷限制流的影响

给出了双向流二极管中阳极发射离子获得初始能量的几种方法，从理论上研究了离子初始能量对二极管内空间电荷限制电子电流、离子电流的影响，并与离子初始能量为。情况下的空间电荷限制电子电流、离子电流进行了比较。     

向日葵种胚的V离子注入研究

利用扫描电子显微镜和能量色散谱仪研究Ｖ离子注入向日葵种胚后注入元素的深度分布，用透射电子显微镜（ＴＥＭ）研究离子注入前后子叶及胚轴部位细胞的显微结构变化。结果发现Ｖ离子在种皮层的注入深度达到１８μｍ，而在胚部位（如子叶、胚轴和胚根等）则没有测到Ｖ元素，注入前后子叶前后和胚轴细胞的显微结构在ＴＥＭ上没有明显的变化。     

低能离子探测器的设计及测试

自行设计制作并测试了用于电子-离子碰撞电离截面测量实验的低能离子探测器。该探测器由Al_2O_3转换板、加速电极、单通道电子倍增器三部分组成。离子沿70°方向轰击转换板,产生数目与离子能量成正比的二次电子,电子由单通道倍增器测量。采用合适的电子学线路和甄别阈,可以有效地把离子计数与本底分开。对10keV Ar~+在入射束流小于10~4s~(-1)时,探测效率接近100％。本探测器可用于低能重离子的计数测量。     

Distribution of implanted ions in seeds and roots of mung bean

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80MeV/u 12C6+离子辐照小鼠头部对骨髓细胞周期分布的影响

研究重离子辐照小鼠头部对骨髓细胞周期分布的影响,为重离子放射治疗癌症和太空防护提供基础数据.80MeV/u能量的12C6 离子对BALB/c小鼠头部给以0、0.5、1、2、4、10Gy的照射,用流式细胞仪测骨髓细胞周期分布.随着重离子辐照剂量的增加,G1/G0期细胞出现明显阻滞(P＜0.05),而G2/M期细胞出现显著减少(P＜0.05).说明重离子辐照小鼠头部对小鼠骨髓细胞周期分布有明显影响,也同时表明电离辐射对骨髓细胞周期分布的影响也有一种间接作用.     

Measurement of Ion Parameters by Ion Sensitive Probe in ECR Plasma

Ion parameters in electron cyclotron resonance (ECR) microwave plasma were measured by ion sensitive probe and were compared with the electron parameters obtained by double Langmuir probe. The effects of gas pressure and microwave power on the ion temperature and density were analyzed. The spatial distribution of the ion parameters was also investigated by the ion sensitive probes with a tunable radial depth installed on different probe windows along the chamber axis. Results showed that the ion density measured by the ion sensitive probe was in good agreement with the electron density measured by the double Langmuir probe. The influence of gas pressure on the ion parameters was stronger than that of microwave power. With the increase in working pressure, the ion temperature decreased monotonously with a decreasing rate larger than that at higher pressure. The ion density first increased to a peak (42.3?1010cm-3) at 1 Pa and then decreased. The ion temperature and density increased little with the increase in the microwave power from 400 W to 800 W. The plasma far away from the resonant point is found to be radially uniform.     

用5—20keV As~+、BF_2~+注入与快速热退火制作超浅结的研究

利用能量为5—20keV、剂量为5×10~(14)—5×10~(15)cm~(-2)的BF~+_2和As~+注入硅中,以快速热退火激活杂质并控制杂质的扩散再分布,可以得到结深～100nm、薄层电阻～60Ω/口的突变p~+-n和n~+-P超浅结。