Influence of ion species ratio on grid-enhanced plasma source ion implantation

Grid-enhanced plasma source ion implantation (GEPSII) is a newly proposed technique to modify the inner-surface properties of a cylindrical bore. In this paper, a two-ion fluid model describing nitrogen molecular ions N_2^+ and atomic ions N^+ is used to investigate the ion sheath dynamics between the grid electrode and the inner surface of a cylindrical bore during the GEPSII process, which is an extension of our previous calculations in which only N_2^+ was considered. Calculations are concentrated on the results of ion dose and impact energy on the target for different ion species ratios in the core plasma. The calculated results show that more atomic ions N^+ in the core plasma can raise the ion impact energy and reduce the ion dose on the target.     

铪离子等离子体源离子注入铜基体的数值模拟

通过SRIM软件对铪离子等离子体源离子注入铜进行了模拟。模拟了铪离子注入铜的核阻止本领、电子阻止本领、入射深度随能量的变化,以及在不同注入条件下铪离子的摩尔浓度分布,并对模拟结果进行了分析。结果显示:能量低于6 MeV时核阻止本领占主导地位,高于6 MeV时电子阻止本领成为主要的能量损失,并且离子注入过程中会出现能量沉积的Bragg峰和质量沉积区域较集中的现象,入射深度随能量的增加而增加。     

铪离子等离子体源离子注入铜基体的数值模拟

通过SRIM软件对铪离子等离子体源离子注入铜进行了模拟。模拟了铪离子注入铜的核阻止本领、电子阻止本领、入射深度随能量的变化,以及在不同注入条件下铪离子的摩尔浓度分布,并对模拟结果进行了分析。结果显示：能量低于6 MeV时核阻止本领占主导地位,高于6 MeV时电子阻止本领成为主要的能量损失,并且离子注入过程中会出现能量沉积的Bragg峰和质量沉积区域较集中的现象,入射深度随能量的增加而增加。     

Two-dimensional particle-in-cell plasma source ion implantation of a prolate spheroid target

A two-dimensional particle-in-cell simulation is used to study the time-dependent evolution of the sheath surrounding a prolate spheroid target during a high voltage pulse in plasma source ion implantation. Our study shows that the potential contour lines pack more closely in the plasma sheath near the vertex of the major axis, i.e. where a thinner sheath is formed, and a non-uniform total ion dose distribution is incident along the surface of the prolate spheroid target due to the focusing of ions by the potential structure. Ion focusing takes place not only at the vertex of the major axis, where dense potential contour lines exist, but also at the vertex of the minor axis, where sparse contour lines exist. This results in two peaks of the received ion dose, locating at the vertices of the major and minor axes of the prolate spheroid target, and an ion dose valley, staying always between the vertices, rather than at the vertex of the minor axis.     

等离子体源离子注入过程中半圆形碗状样品的两维温度分布

等离子体源离子注入过程(PSII)中样品温度是一个非常重要的参量。由于注入到样品上的能量很大，导致样品温度很高，所以在实验中获知样品的温度分布有着很重要的意义。本文利用热传导方程建立了半圆形碗状样品内部温度升高模型，研究样品内温度演化过程。以注入离子束流作为能量输入项，热辐射为能量损失项，并考虑了热辐射过程中样品的形状因子的影响。考察了离子注入过程中样品上所施加负偏压的脉冲宽度和频率对样品温度分布的影响。研究结果显示，脉冲频率达到一定值后，样品温度不再随频率增加而升高。     

Modification of wetting properties of CR39 by plasma source ion implantation

Plasma source ion implantation (PSII), a hybrid implantation technique between ion beams and immersion plasmas has been used to modify CR39 surfaces for improved wettability providing both advancing (θ_a) and receding (θ_r) contact angles below 5°. The modifications brought to the polymer surface structure have been characterized by X-ray photoelectron spectroscopy (XPS) and its combination with chemical derivatization (CD-XPS). Oxygen desorption has been observed in spite of the very hydrophilic surfaces. C_1s XPS peak has been displaced toward greater energies, while the opposite has been found for O_1s, both involving new components and strong modifications after ion implantation treatment. Strong evidences about the formation of new chemical functions, like OOH, COOH and CC, have been found and have provided an explanation for the increased wettability.     

半圆形容器等离子体源离子注入过程中离子动力学的两维PIC计算机模拟

利用两维particle-in-cell方法研究了半圆形容器表面等离子体源离子注入过程中鞘层的时空演化规律. 详尽考察了鞘层内随时间变化的电势分布和离子密度分布规律,离子在鞘层中的运动轨迹和运动状态,得到了半圆容器内、外表面和边缘平面上各点离子注入剂量分布规律,获得了工件表面各点注入离子的入射角分布规律. 研究结果揭示了半圆容器边缘附近鞘层中离子聚焦现象,以及离子聚焦现象导致工件表面注入剂量分布和注入角度分布存在很大不均匀的基本物理规律. 关键词： 等离子体源离子注入 鞘层 两维particle-in-cell方法 离子运动轨迹     

The simulation of two-beam high-dose ion implantation into solid targets

A physicomathematical model and a BEAM2HD program for the dynamic simulation of one-and two-beam high-dose ion implantation into multilayer and multicomponent targets are developed. The number of target layers is no more than three, and the number of sorts of atoms in each of the layers is no more than seven. The simulation is performed by the Monte Carlo method. Numerical results for the formation of C _x→3N _y→4 superhard layers by two-beam high-dose implantation of nitrogen ions into the Si₃N₄/C/Si₃N₄/Si system are presented.     

高频离子源等离子体的光谱诊断

采用发射光谱法研究了高频离子源的等离子体性质。该离子源应用于ZF-200keV中子发生器中,是一种电感耦合型无极环形放电高频离子源。实验采用绝对定标后的光学多道分析系统测定了离子源等离子体在不同阶段氢原子巴耳末谱线系中前三条谱线的强度,并采用部分局部热力学平衡状态的理论,计算出了相应阶段高频离子源等离子体的电子温度、氢原子浓度、氢离子浓度等参数,并进行了简要分析。     

高频离子源等离子体的光谱诊断

 采用发射光谱法研究了高频离子源的等离子体性质。该离子源应用于ZF-200keV中子发生器中，是一种电感耦合型无极环形放电高频离子源。实验采用绝对定标后的光学多道分析系统测定了离子源等离子体在不同阶段氢原子巴耳末谱线系中前三条谱线的强度，并采用部分局部热力学平衡状态的理论，计算出了相应阶段高频离子源等离子体的电子温度、氢原子浓度、氢离子浓度等参数，并进行了简要分析。     

Low pressure plasma immersion ion implantation of silicon

Mono-energetic plasma immersion ion implantation (PIII) into silicon can be attained only under collisionless plasma conditions. In order to reduce the current load on the high voltage power supply and modulator and sample heating caused by implanted ions, the plasma pressure must be kept low (<1 mtorr). Low pressure PIII is therefore the preferred technique for silicon PIII processing such as the formation of silicon on insulator. Using our model, we simulate the characteristics of low pressure PIII and identify the proper process windows of hydrogen PIII for the ion-cut process. Experiments are conducted to investigate details in three of the most important parameters in low pressure PIII: pulse width, voltage, and gas pressure. We also study the case of an infinitely long pulse, that is, dc PIII     

强流磁约束金属离子注入源

设计和制造了适合工业应用的强流金属离子源。离子源的电弧阴、阳电极之间和放电室壁采用永磁体阵列形成导流、屏蔽磁场,改进了电弧的放电特性和提高等离子体密度。离子注入源在加速电压为30kV、50 Hz 条件时,平均束流流强约为30mA,调试结果表明附加磁场提高了离子源性能。     

Multi-element focused ion beams using compact microwave plasma ion source

Focused ion beams (FIB) are widely used for research and applications in nanoscience and technology. We have developed a compact microwave plasma based multi element FIB (MEFIB) system in order to widen the applications and overcome the limitations faced by conventional Liquid Metal Ion Source (LMIS) based FIB systems, that provide primarily Ga ions. The MEFIB source provides high density plasmas (∼1.5 × 10¹¹ cm⁻³) in a compact cross section. Recently the ion energy spread in the plasma meniscus from where the beams are extracted is found to be small (∼5 eV) [1–3]. The beam extraction and focusing are carried out using electrostatic multi electrode assembly. AXCEL INP and SIMION simulation codes are employed for the design of electrostatic Einzel lenses for beam focusing. The beam focal point is measured using a specially designed three slit Faraday cup and the spot size is measured by the micrography of craters formed by the focused ion beams impinging on copper and aluminium substrates. The initial experimental results show a focused beam spot size of ∼ 25 micron which is in good agreement with the simulations. By further reduction of electrode apertures and operating the second Einzel lens at higher potentials, submicron focused ion beams can be expected.     

微波ECR全方位离子注入制备类金刚石碳膜的结构及摩擦学性能研究

利用微波ECR全方位离子注入技术，在单晶硅（100）衬底上制备类金刚石薄膜.分析结果表明，所制备的类金刚石碳膜具有典型的类金刚石结构特征，薄膜均匀、致密，表面粗糙度小，摩擦系数小.其中，薄膜的结构和性能与氢流量比关系密切，随氢流量比的增加，薄膜的沉积速率减小，表面粗糙度降低，且生成sp³键更加趋向于金刚石结构，表面能 更低，从而使摩擦系数大幅降低. 关键词： 全方位离子注入 类金刚石碳膜 拉曼光谱 摩擦磨损     

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为了更好地提高引出离子束的均匀性,对离子束刻蚀用矩形射频电感耦合等离子体(ICP)离子束源提出了三种线圈的设计方法,并对这三种线圈激发的电场进行了数值计算和比较。结果表明,直线段式不等距天线和并联多螺旋不等距天线线圈能够产生均匀性良好的电场,且其耦合效率高。     

Control of implantation area in direct-current plasma immersion ion implantation (DC-PIII)

In plasma immersion ion implantation (PIII) of planar samples such as silicon wafers in the PIII-ion-cut as well as separation by plasma implantation of oxygen (SPIMOX) processes, the only important ions are the ones arriving at the top surface. Ions implanted into the other surfaces are, in fact, undesirable as they reduce the efficiency of the power supply and plasma source and give rise to metallic contamination. We have demonstrated direct-current PIII (DC-PIII) by using a grounded grid to separate the vacuum chamber for planar sample implantation. The advantages include lower equipment cost, higher power and time efficiency, larger impact energy, and last but not least, smaller instrument footprint. In this paper, we investigate the control of the implantation area by adjusting the radius of the extraction hole, the distance between the conducting grid and the sample, and the radius of the wafer stage. Theoretical simulation is conducted using particle-in-cell and experiments are also carried out. Our results indicate that the implanted area increases with the radius of the extraction hole and wafer stage, but decreases with a larger distance between the grid and sample. The effects of the extraction hole radius G/sub r/ are the largest, followed by the placement of the sample to the conducting grid H. The wafer stage poses the least influence in this respect, but a proper wafer stage dimension improves the lateral implant dose and incident angle homogeneity. Our simulation and experimental results suggest optimal ratios of these parameters for each wafer size.     

Properties of TiN coating on 45# steel for inner surface modification by grid-enhanced plasma source ion implantation method

Using a new inner surface modification method named GEPSII (grid-enhanced plasma source ion implantation), which is designed for inner surface modification of tubular work pieces, we successfully produced polycrystalline TiN coating on 0.45% C steel (45^# steel) samples. Compared with the uncoated 45^# steel sample, the electrochemical corrosion test on the coated 45^# steel samples presents evident improvement in their corrosion resistance. Two implanted voltages, direct current (－2kV) and pulsed negative voltage (－10kV), are applied on the substrates. It is shown that the direct current implantation is more effective than the pulsed implantation in the surface corrosion resistance. AES depth profile shows that coating thickness is about tens of nanometres. The preferred orientations expressed by peaks at (111) and (200) can be seen clearly in XRD patterns.     

Ablation plasma ion implantation using a dc power supply

Experiments are reported in which ablation plasma ion implantation (APII) has been demonstrated using a dc power supply. The ability to use a dc power supply for APII has been accomplished by using a perpendicular orientation between the target and the substrate. This perpendicular orientation significantly reduces the arcing between the target and the substrate, in contrast to previous experiments using a parallel target–substrate orientation. With this new technique a KrF laser may be fired during the dc high voltage, accelerating full-energy ions. Initial experiments using dc APII have shown that Ti is deposited and implanted onto the Si substrate, with the highest concentration of Ti located beneath the surface of the film. The deposition/implantation of Ti ions onto Si was verified by X-ray photoelectron spectroscopy. PACS 52.38.Mf     

Two-dimensional modeling and simulation for dynamic sheathexpansion during plasma immersion ion implantation

A pseudo two-dimensional (2-D) analytical model and a 2-D plasma simulator PDP2 code have been utilized to characterize ion-matrix sheath and dynamic sheath expansion during the plasma immersion ion implantation process. The pseudo 2-D model is very simple by involving two geometry factors and yields an acceptable accuracy under the current process conditions. Good agreement between the pseudo 2-D model and PDP2 simulation was observed     

强流激光离子源中的等离子体参数诊断

强流激光离子源是最有希望为重离子聚变直线感应加速器提供离子的离子源之一。离子源内等离子体决定了离子源性能和引出品质,为了了解强流激光离子源内等离子体参数,采用发射光谱和ICCD成像的方法对该离子源中的等离子体进行了诊断。该离子源由一台四倍频的266 nm Nd:YAG激光器和Cu靶组成,激光束经过透镜聚焦后照射在Cu靶上产生等离子体,激光打靶能量密度约为108 W/cm2,持续时间15 ns。ICCD相机拍摄了激光照射后等离子体的膨胀过程,初始时刻等离子体垂直表面喷射,膨胀速度约为1 cm/s。光谱仪测量了离子发射光谱,谱线主要由Cu原子的Cu Ⅰ谱线和Cu+离子的Cu Ⅱ谱线组成。采用Boltzmann图法得到膨胀等离子体电子激发温度约为1 eV,采用Stark展宽法得到电子密度约为1016 cm-3。