用于薄膜制备的射频宽束离子源的设计

采用射频宽束离子源进行离子束辅助镀膜可以获得高性能的光学薄膜,已越来越得到人们的共识.本文对射频感应线圈的匹配、起弧及三栅离子光学的关键技术进行了重点考虑，并获得了稳定运行的高性能离子源.     

射频阻抗基准

中国计量科学研究院1981年开始研究的射频阻抗基准，于1984年通过国家鉴定，1986年由原国家计量局正式批准为国家基准。该基准由精密同轴空气线以及开路器、短路器和sod终端标准件组成。空气介质同轴线的阻抗数值可由问轴线的尺寸和材料的电磁特性理论计算得到，因此空气介质同轴线阻抗可作为高频阻抗的绝对标准，可用它准确校准按反射系数测量原理设计的高频阻抗分析仪。该基准的研制成功，为我国射频阻抗测量建立国家实物基准，为保证射频阻抗量值的统一、射频阻抗的测试定标创造了有利条件和可靠手段。该基准经过长期使用，一直保持良好…     

中子管射频离子源放电特性仿真研究北大核心CSCD

国外射频离子源中子管的中子产额已经达到10^14n/s,明显优于潘宁源中子管。为了深入了解用于中子管射频离子源的放电特性,从射频感应耦合等离子体的放电原理入手,建立用于氢气放电模拟研究的理论模型。设计中子管射频离子源几何结构,运用麦克斯韦方程组在理论上推导了等离子体放电过程中影响粒子密度的因素。结合Comsol软件中的二维轴对称的电感耦合等离子体模型,采用单一变量法,通过仿真实验得到了线圈匝间距、线圈匝数、线圈直径、线圈功率和放电气压等参数对H^+密度分布和大小的影响。总结出H+在不同参数下的变化规律,得到了一些有价值的结论,为优化中子管射频离子源的实验参数和结构设计提供重要依据。     

低能宽束离子源的研究进展

低能宽束离子源是离子束沉积、刻蚀和表面改性系统的核心部件,综述了考夫曼、射频等离子体、电子回旋共振等离子体、无栅网等四种离子源的等离子体的产生方式,对结构重点进行了分析,并从参数性能上进行了比较.稳定性好、与反应气体兼容的特点使射频和电子回旋共振离子源在低能离子束系统中取得了广泛应用,由于结构简单,束散角大,无栅网离子源目前仅限应用于薄膜沉积和薄膜改性等.     

中子管射频离子源放电特性仿真研究

国外射频离子源中子管的中子产额已经达到10~(14) n/s,明显优于潘宁源中子管。为了深入了解用于中子管射频离子源的放电特性,从射频感应耦合等离子体的放电原理入手,建立用于氢气放电模拟研究的理论模型。设计中子管射频离子源几何结构,运用麦克斯韦方程组在理论上推导了等离子体放电过程中影响粒子密度的因素。结合Comsol软件中的二维轴对称的电感耦合等离子体模型,采用单一变量法,通过仿真实验得到了线圈匝间距、线圈匝数、线圈直径、线圈功率和放电气压等参数对H~+密度分布和大小的影响。总结出H~+在不同参数下的变化规律,得到了一些有价值的结论,为优化中子管射频离子源的实验参数和结构设计提供重要依据。     

射频阻抗标准器量值定标及溯源技术研究

射频阻抗标准器是验证射频阻抗测量仪器计量性能的关键装置,可建立仪器内部存储的基准数据与国家阻抗基准的溯源关系。本文分析了10cm同轴无支撑空气线、短路标准器、开路标准器和50Ω阻抗匹配标准器的结构,基于传输线理论,运用等效、样条插值等算法,对射频阻抗标准器进行定值,并对定标值进行不确定度评定,建立了射频阻抗标准器量值与物理尺寸及国家微波阻抗基准的溯源关系,解决了目前射频阻抗量值溯源和量值传递的交叉重叠问题。     

离子源辅助电子束沉积凹印版耐磨层

针时凹印版电镀存在的污染和高能耗，采用射频感应偶合（ICP）离子源辅助电子束沉积硬质铬耐磨层，通过控制离子源参数和加入过渡层来提高薄膜与基体的结合力和显微硬度。利用扫描电镜、原子力显微镜、显微硬度计、划痕仪、表面轮廓仪，摩擦磨损仪对膜层的组织结构和性能进行了研究，探讨了在薄膜沉积过程中，离子源工艺参数对薄膜界面结合机理，组织结构和性能的影响。     

射频离子源朗缪尔双探针设计

射频离子源具有的复杂电磁环境会干扰甚至使得朗缪尔单探针无法准确获得等离子体参数。双探针具有对等离子体的干扰较小,不需要参考电位等优点,因此更加适用于射频离子源下的等离子体诊断。为了使得朗缪尔双探针更加精确地测量电子温度与离子密度,必需在测量电路中增加针对干扰源频率的滤波电路系统。本文针对射频离子源等离子体诊断设计了探针测量电路,并进行了仿真计算和分析,结果表明:探针的抗干扰能力与测量精度均具有明显的改善。     

容性耦合射频（CCRF）放电等离子体特性实验研究

利用自行研制的传感器和测量装置，通过对放射频放电电压电流以及其相位角的测定，算出放电算的总阻抗，结合放电管的等效电路，对容性耦合射频（CCRF）激励激光放电特性进行研究，得出容性耦合射频激励激光器等离子体的伏安特性的曲线，以及等离子体电阻，容抗与气体压器，放电电流之间的实验曲线，在Godyak射频放电模型的基础上得出等离子体的电子密度，并同内置铜电极射频激励铜离子激光器阻抗特性进行了比较。     

射频ICP离子源设计研究

本文介绍了射频 (RF)感应耦合等离子体 (ICP)离子源的设计研究。对RFICP的结构、离子流的引出以及离子流的均匀性、中性化和射频匹配网络进行了研究。     

Design and Construction of a Helical Resonator for Delivering Radio Frequency to an Ion Trap

Supplying high voltage radio frequency (RF) is a critical part of ion trapping system due to impedance mismatching between RF source and the ion trap. A helical resonator has been constructed in order to deliver narrow bandwidth and high voltage RF to the ion trap for stable confinement of ions. The performances of the helical resonator have been studied for different capacitive load of the ion trap. Both the resonant frequency and quality factor of the resonator show strong dependence on external capacitive loads.     

Use of plasma impedance monitoring for the determination of SF6 reactive ion etch process end points in a SiO2/Si system

It is shown here that plasma impedance monitoring can be used successfully to determine the end point of reactive ion etching of a SiO₂ layer lying on a Si substrate in SF₆ plasma. The usefulness of this technique is demonstrated using a commercial Plasma Impedance Monitoring (PIM) system. The end point conditions are tested by monitoring changes in the fundamental and the first four harmonic components of the RF current, RF voltage, phase between RF voltage and current, RF discharge power and RF impedance. The best process monitoring parameter found in this work is modeled as a polynomial equation of RF input power, chamber pressure and gas flow rate, from which the end point can be predicted with good precision and easily detected by the PIM. The end point conditions are confirmed by both Fourier Transform Infrared Spectroscopy (FTIR) measurements and via observation of plasma color changes. Received:15 June 2001 / Accepted: 18 June 2001     

用于静电加速器的高频离子源的设计和调试

研制了一台高频离子源 ,通过实验调试取得了引出电压、聚焦电压及放电气压对引出束流影响的变化曲线 ,从而获得高频离子源的最佳工作条件 ,并测定了引出束流的束径包络     

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.     

A new low-cost RF built-in self-test measurement for system-on-chip transceivers

This paper presents a new RF built-in self-test (BIST) measurement and a new automatic-performance-compensation network for a system-on-chip (SoC) transceiver. We built a 5-GHz low noise amplifier (LNA) with an on-chip BIST circuit using 0.18-/spl mu/m SiGe technology. The BIST-measurement circuit contains a test amplifier and RF peak detectors. The complete measurement setup contains an LNA with a BIST circuit, an external RF source, RF relays, 50-/spl Omega/ load impedance, and a dc voltmeter. The proposed BIST circuit measures input impedance, gain, noise figure, input return loss, and output signal-to-noise ratio of the LNA. The test technique utilizes the output dc-voltage measurements, and these measured values are translated to the LNA specifications such as the gain through the developed equations. The performance of the LNA was improved by using the new automatic compensation network (ACN) that adjusts the performance of the LNA with the processor in the SoC transceiver.     

Development of a dedicated ion injector for accelerator-based nanoprobe facilities

The paper discusses possible ways of increasing beam brightness in ion injectors. The argon/helium ion injector comprising a newly designed RF ion source and, a Wien filter has been designed for use in accelerator-based nanoprobe facilities. The phase set degradation due to aberrations in the injector ion-optic system was simulated with allowance for multipole and fringing fields. The RF ion sources with different permanent magnet systems were tested. Experiments were performed with argon and helium. A plasma density of up to 3×10¹¹ cm⁻³ and beam brightness of ∼100 A/(m² rad² eV) were obtained. The ion current density inside an extracting electrode in the source was 10 mA/cm² for an emission hole diameter of 0.6 mm. Measurements of the current value and emittance were performed with ion source testing equipment permitting measurements of the ion beam current, emittance, mass composition, and RF power input into the plasma.     

高频离子源的光学设计

ns-200中子发生器采用的是高频离子源,面临着提高离子源的性能,增大引出束流的技术改造问题。为此开展了高频离子源的设计研制工作。高频离子源采用管道式引出结构和三圆筒单透镜聚焦系统。根据设计指标要求和离子光学原理,经过计算和优化,确定了引出系统和聚焦系统的主要参数。采用传输矩阵和束矩阵(σ矩阵)相结合的数值计算方法,运用LEADS软件模拟计算了束流传输过程,模拟计算的结果与理论设计相吻合。在ns-200中子发生器上进行了初步的实验,表明设计的高频离子源束流光学系统是合理的。     

静电加速器高频离子源引出电极的光学设计

高频离子源管道式引出电极的几何参数对束流引出具有重要影响。本文通过建立束流最佳引出数学模型 ,对引出电极的几何参数进行了离子光学计算 ,确定了适合引出H ,N ,Ar 等多种束流的引出电极合适的几何参数 ,并综合气耗、束流强度等因素设计了用于 5 5MeV静电加速器高频离子源的引出电极。理论计算和实验表明了该设计方法的有效性     

磁共振成像交替阻抗微带线射频线圈仿真分析

为研究改变交替阻抗微带线射频线圈的几何尺寸对感兴趣区内磁场分布的影响,保持微带线射频线圈总长度不变,改变宽带与窄带的长度比例和宽度比例,在HFSS中建立交替阻抗微带线射频线圈的仿真模型,与传统微带线射频线圈进行比较,利用ADS与HFSS的协同仿真实现线圈的调谐和匹配.仿真结果表明交替阻抗微带线射频线圈感兴趣区内的磁场均值比传统微带线射频线圈的提高了一倍以上.调整交替阻抗微带线射频线圈的宽带与窄带的长度比例和宽度比例,可以提高感兴趣区内的磁场强度,同时改善磁场分布的均匀性.