用沟道技术研究反应离子束刻蚀所引起的晶体表面损伤

在大规模集成电路发展过程中,随着集成度的不断提高,要求电路的线条不断变细,等离子、离子束及反应离子刻蚀等加工工艺将起着重要的作用。它们为大规模集成电路生产提供了强有力的微细加工手段。离子束刻蚀类似于机械研磨,离子束能量和样品的位置可变,具有各向异性。在加工过程中,样品表面存在一定量的损伤,从貌相看还存在起伏不平的“小丘”。等离子和反应离子刻蚀克服了各项异性,但离子能量和刻蚀的方向不可调节,所以也有局限性。     

Ion beam enhanced etching of LiNbO3

Single crystals of z- and x-cut LiNbO₃ were irradiated at room temperature and 15 K using He⁺- and Ar⁺-ions with energies of 40 and 350 keV and ion fluences between 5 × 10¹² and 5 × 10¹⁶ cm⁻². The damage formation investigated with Rutherford backscattering spectrometry (RBS) channeling analysis depends on the irradiation temperature as well as the ion species. For instance, He⁺-irradiation of z-cut material at 300 K provokes complete amorphization at 2.0 dpa (displacements per target atom). In contrast, 0.4 dpa is sufficient to amorphize the LiNbO₃ in the case of Ar⁺-irradiation. Irradiation at 15 K reduces the number of displacements per atom necessary for amorphization. To study the etching behavior, 400 nm thick amorphous layers were generated via multiple irradiation with He⁺- and Ar⁺-ions of different energies and fluences. Etching was performed in a 3.6% hydrofluoric (HF) solution at 40 °C. Although the etching rate of the perfect crystal is negligible, that of the amorphized regions amounts to 80 nm min⁻¹. The influence of the ion species, the fluence, the irradiation temperature and subsequent thermal treatment on damage and etching of LiNbO₃ are discussed.     

Ion beam propagation and focusing

Inertial confinement fusion with ion beams requires the efficient delivery of high energy (1 MJ), high power (100 TW) ion beams to a small fusion target. The propagation and focusing of such beams is the subject of this paper. Fundamental constraints on ion beam propagation and focusing are discussed, and ion beam propagation modes are categorized. For light ion fusion (LIF), large currents (2–33 MA) of moderate energy (3–50 MeV) ions of low atomic number (1A12) must be directed to a target of radius 1 cm. The development of pulsed power ion diodes for LIF is discussed, and the necessity for virtually complete charge neutralization during transport and focusing is emphasized. Fornear-term LIF experiments, the goal is to produce pellet ignition without the standoff needed for the ultimate reactor application. Ion diodes for use on Sandia National Laboratories Particle Beam Fusion Accelerators PBFA-I (2–4 MV, 1 MJ, 30 TW, operational) and PBFA-II (2–16 MV, 3.5 MJ, 100 TW, scheduled for operation in 1985) are discussed. Ion beam transport from these diodes to the pellet is examined in reference to the power brightness . While values of =2–5 TW/cm²/sr have been achieved to date, a value of 100 TW/cm²/sr is needed for breakeven. Research is now directed toward increasing , and means already exist (e.g., scaling to higher voltages, enhanced ion diode current densities, and bunching), which indicate that the required goal should be attainable. Forfar-term LIF applications, the goal is to produce net energy gain with standoff suitable for a reactor. This may be achieved by ion beam transport in preformed, current-carrying plasma channels. Channel transport research is discussed, including experiments with wire-initiated, wall-initiated, and laser-initiated discharge channels, all of which have demonstrated transport with high efficiency (50–100%). Alternate approaches to LIF are also discussed, including comoving electron beam schemes and a neutralized beam scheme. For heavy ion fusion (HIF), moderate currents (10 kA) of high energy (10 GeV) ions of high atomic number (A200) must be directed to a target of radius 0.3 cm. Conventional accelerator drivers for HIF are noted. For a baseline HIF reactor system, the optimum transport mode for low charge state beams is ballistic transport in near vacuum (10^–4–10^–3 Torr lithium), although a host of other possibilities exists. Development of transport modes suitable for higher charge state HIF beams may ultimately result in more economical HIF accelerator schemes. Alternate approaches to HIF are also discussed which involve collective effects accelerators. The status of the various ion beam transport and focusing modes for LIF and HIF are summarized, and the directions of future research are indicated.     

离子束分析在艺术和考古学中的应用

本文通过与运用其它分析技术的同类工作进行比较来述评离子束分析法在艺术和考古学研究中的应用。为了说明离子束分析法的利弊,精选了一些实例来阐述该方法在艺术和考古学领域中的发展趋势和重要成就。     

Ion beam characterization of advanced luminescent materials for application in radiation effects microscopy

The ion photon emission microscope (IPEM) is a technique developed at Sandia National Laboratories (SNL) to study radiation effects in integrated circuits with high energy, heavy ions, such as those produced by the 88” cyclotron at Lawrence Berkeley National Laboratory (LBNL). In this method, an ion-luminescent film is used to produce photons from the point of ion impact. The photons emitted due to an ion impact are imaged on a position-sensitive detector to determine the location of a single event effect (SEE). Due to stringent resolution, intensity, wavelength, decay time, and radiation tolerance demands, an engineered material with very specific properties is required to act as the luminescent film. The requirements for this material are extensive. It must produce a high enough induced luminescent intensity so at least one photon is detected per ion hit. The emission wavelength must match the sensitivity of the detector used, and the luminescent decay time must be short enough to limit accidental coincidences. In addition, the material must be easy to handle and its luminescent properties must be tolerant to radiation damage. Materials studied for this application include plastic scintillators, GaN and GaN/InGaN quantum well structures, and lanthanide-activated ceramic phosphors. Results from characterization studies on these materials will be presented; including photoluminescence, cathodoluminescence, ion beam induced luminescence, luminescent decay times, and radiation damage. Results indicate that the ceramic phosphors are currently proving to be the ideal material for IPEM investigations.     

用于EBIT装置的小型MEVVA源及其离子注入实验

为给上海电子束离子阱(Electron Beam Ion Traps,EBIT)装置提供低电荷离子,我们研制了小型金属蒸汽真空弧(Metal Vapor Vacuum Arc,MEVVA)离子源,可产生多种金属以及半导体材料的低电荷离子.本文介绍小型MEVVA离子源的特性及其在上海EBIT装置上的离子注入实验.实验结果显示,合理控制注入参数可以使注入并被束缚在EBIT中的离子数密度达到108～109/cm3.     

微波离子枪离子束光学的数值模拟

用数值模拟方法研究了聚焦离子束系统中微波离子枪的束光学性能，将离子枪看作由源等离子体极和Ｏｒｌｏｆｆ－Ｓｗａｎｓｏｎ透镜组成的双级加速系统，分析了各参对束发射特性的影响。结果展示出引出束光学主要取决于引出导流系数和电势分布，在一定条件下可获得发散度小的离子束。     

10cm×30cm矩形射频离子束源的研制

本文介绍了射频(Radio frequency,RF)感应耦合等离子体(Inductive couple plasma,ICP)离子束源的设计研究.该射频离子束源可工作于Ar,在使用四栅引出系统时,可获得100-1000 eV的离子束.当射频功率为900 W,在Ar为工作气体时,束流可达到600 mA.在束流为120 mA时,距源26 cm处,在主轴方向27 cm的范围内不均匀性小于±6%.该离子束源可作为大面积离子束刻蚀、离子束抛光等的离子束源.     

强脉冲离子束辐照混合的RBS研究

采用卢瑟福背散射(Rutherford backscattering spectroscopy,RBS)方法对强脉冲离子束辐照Ti/Al、Al/Ti和Ni/Ti三组薄膜/衬底体系所形成的混合层进行了研究.在Ni/Ti组合中形成了厚度比离子射程大得多的、混合度较高的梯度混合层.发现熔融态混合的程度不仅取决于两材料在熔融态的表面张力的差别,而且取决于它们熔点的差异.这两个参量较接近的混合程度较好.     

茯苓聚糖的氚离子束标记及其在小鼠体内的药物动力学研究

本文采用氚离子束标记法,对茯苓聚糖进行了标记,放射性比活性达1.81—2.07TBq/mmol。药物动力学研究证明~3H-茯苓聚糖尿素液口服灌喂小白鼠,按一定时间在尾部静脉取血样作放射性分析。得到的药-时曲线适合于双定模型。