同步辐射x射线光刻制作深亚微米T形栅

x射线光刻非常适合用于深亚微米T形栅的制作,这是因为它的高分辨率、大的曝光视场和高的生产效率足以满足MMIC制造工艺的要求。本文中我们首先对我们的x射线掩模制造工艺进行介绍,然后论述了一种用于制造深亚微米T形栅的两层胶工艺,介绍了所取得的一些研究结果,最后对国内的深亚微米光刻现状进行了简要分析。     

深亚微米同步辐射x射线光刻技术

报道了我们制作深亚微米 x射线掩模的工艺和同步辐射 x射线曝光工艺 ,并报道了我们在北京同步辐射装置 (BSRF) 3B1 A光刻束线所获得的深亚微米 x射线光刻图形的实验结果     

深亚微米同步辐射x射线光刻模拟

用束衍生法研究了深亚微米同步辐射 x射线光刻中掩模吸收体的光导波效应 ,并对 x射线光刻后的光刻胶剖面进行了理论计算。采用面向对象技术 ,研制了一个取名为 XLLS1 .0的模拟软件。本文对这个软件进行了详细介绍     

接近式光刻的计算机模拟研究

分析了菲涅耳近似模型在接近式光刻模拟中的应用和误差起源 ,并根据光的标量衍射理论 ,对菲涅耳近似模型进行了修正 ,得到了更加准确的类菲涅耳近似模型 ;并对这两种模型的模拟结果进行了比较     

X-ray lithography induced radiation damage in CMOS and bipolar devices

Radiation effects from a synchroton x-ray lithography source on the performance degradation and long term reliability of high performance self-aligned bipolar devices and deep sub-micron CMOS devices are studied. The hot-carrier properties of the x-ray induced damage in CMOS devices, such as interface states, positive oxide charges and neutral traps have been examined. The effect of these radiation induced defects and their impact on the DRAM circuits in terms of the performance and reliability are discussed. In the self-aligned, double polysilicon bipolar transistor structure interface states and trapped charges can be generated by the radiation source in the sidewall oxide near the emitter-base junction such damage can increase the emitter-base leakage current. This increase of base current can substantially degrade the device current gain at low bias.     

同步辐射X射线光刻实验研究

同步辐射X射线光刻是一种很好的深亚微米图形复制技术。本文报道了北京同步辐射装置3BlA光刻束线上的曝光结果，并对X射线掩模的制作工艺作了简要介绍。     

Radiation damage effects on bipolar and MOS devices in X-Ray lithography

Radiation damage effects of bipolar and MOS transistors have been investigated using the vacuum ultraviolet (VUV) storage ring of the national synchrotron light source (NSLS). The devices under investigation were exposed to x-ray radiation and electrical measurements were performed to determine the radiation effects on device parameters. It was found for bipolar devices that the current gain is the parameter that is most sensitive to x-ray irradiation. The current gain decreases as the dose increases and the degradation reaches saturation at 1000 mJ/cm². Upon annealing in forming gas at 400° C for 30 min, the current gain recovered its pre-irradiation value and stress test did not show any reliability problem. Bothn-channel andp-channel MOS devices with polysilicon gates were investigated. Host of the relevant device parameters were measured before and after irradiation and after annealing. Upon irradiation the threshold voltage shows the most obvious shift, which was more negative in both cases. However, thep- channel devices experienced a much larger shift than then-channel ones. The transconductance of the devices also experienced a shift.     

同步辐射硬X射线弧矢聚焦单色化技术的研究

介绍了光束在5－25keV弧矢聚焦单色仪中的单色化及聚焦原理。光束弧矢聚焦单色化原理是指以Bragg定律（2dsinθ=nλ）为基础，改变Bragg角θ，获得所需的波长λ来实现光束的单色化。根据Bragg角θ和压弯晶体的弧矢半径R之间的关系，使单色光束通过弧矢聚焦晶体改变方向并实现单色光聚焦；说明了以柔性铰链为基础的弧矢压弯原理，压弯晶体鞍型形变的抑制、保证出射光与入射光高差固定的结构原理、压弯晶体衍射面面形误差的有限元分析结果；给出了实验结果。     

Radiation damage and its effect on hot-carrier induced instability of 0.5 μm CMOS devices patterned using synchrotron x-ray lithography

The device characteristics and the radiation damgae ofn-channel andp-channel MOSFETs patterned using synchrotron x-ray lithography are examined. The effect of radiation damage caused by x-ray lithography on the device reliability during hot electron injection is investigated. In addition to neutral traps, large amounts of positive oxide charge and interface states, particularly acceptor-like interface states, which cause degradation of MOSFET characteristics are found to be created by x-ray irradiation during the lithography process. Although several annealing steps are performed throughout the entire fabrication process, the radiation damage, particularly neutral traps, is not completely annealed out. The hot-electron induced instability inp-channel MOSFETs is significantly increased due to the enhanced electron trapping in the oxide by residual traps. The effect of radiation damage on hot electron induced instability is found to be more severe inn ⁺-poly buried-channelp-MOSFETs than inp ⁺-poly surface-channel p-MOSFETs. However, the degradation inn-channel MOSFETs due to channel hot carriers is not significantly increased by x-ray lithography. These results suggest that the major degradation mechanism due to hot-carrier inp-channel MOSFETs is electron trapping and inn-channel MOSFETs is interface state generation. It also suggests thatp-channel MOSFETs, in addition ton-channel MOSFETs, needs to be carefully examined in terms of hot carrier induced instability in CMOS VLSI circuits patterned using x-ray lithography.     

LIGA技术的掩模制造

ＬＩＧＡ技术是近几年才发展起来的一门新的技术，包括光刻、电铸和塑铸。由于要进行深度Ｘ光曝光，所用的同步辐射Ｘ光较硬，这一曝光条件相应就需要Ｘ光掩模吸收全有较大厚度和较高的加工精度，这样才能够阻档住Ｘ光，同时保证较高的光刻精度。     

Intermetallic phase detection in lead-free solders using synchrotron x-ray diffraction

The high-intensity, high-resolution x-ray source at the European Synchrotron Radiation Facility (ESRF) has been used in x-ray diffraction (XRD) experiments to detect intermetallic compounds (IMCs) in lead-free solder bumps. The IMCs found in 95.5Sn3.8Ag0.7Cu solder bumps on Cu pads with electroplated-nickel immersion-gold (ENIG) surface finish are consistent with results based on traditional destructive methods. Moreover, after positive identification of the IMCs from the diffraction data, spatial distribution plots over the entire bump were obtained. These spatial distributions for selected intermetallic phases display the layer thickness and confirm the locations of the IMCs. For isothermally aged solder samples, results have shown that much thicker layers of IMCs have grown from the pad interface into the bulk of the solder. Additionally, the XRD technique has also been used in a temperature-resolved mode to observe the formation of IMCs, in situ, during the solidification of the solder joint. The results demonstrate that the XRD technique is very attractive as it allows for nondestructive investigations to be performed on expensive state-of-the-art electronic components, thereby allowing new, lead-free materials to be fully characterized.     

Electric‐Field‐Induced Pattern Morphologies in Thin Liquid Films

Liquid‐polymer films sandwiched between two electrodes develop a surface instability caused by the electric field, giving rise to polymer structures that span the two plates. This study investigates the development of the resulting polymer morphologies as a function of time. The initial phase of the structure formation process is a sinusoidal surface undulation, irrespective of the sample parameters. The later stages of pattern formation depend on the relative amount of polymer in the capacitor gap (filling ratio). For high enough filling ratios, the final morphology of the pattern is determined by the partial coalescence of the initial pattern. The introduction of lateral‐field heterogeneities influences the initial pattern formation, with columns nucleated at locations of highest electric field (isolated points or edges). The subsequently formed secondary columns have higher degree of lateral symmetry compared to the pattern formed in a homogeneous field. The nucleation of individual columns or plugs also dominates the pattern formation in the presence of an electrode consisting of an array of lines. The results of this study therefore allow us to draw the conclusion that the accurate replication of structured electrodes typically proceeds by the initial nucleation of individual columns, followed by a coalescence process that yields the polymer replica.     

掩模版复印工艺图形畸变分析与改进

批量化、低成本的掩模版复印工艺常被用于LED领域。在微米级图形的掩模版复印工艺中,受玻璃基板平面度的影响,光学衍射效应会导致图形发生畸变。为消弭复印工艺中的图形畸变,从光学衍射理论展开分析,提出通过调整光刻曝光剂量和光刻胶层厚度来提升掩模版复印工艺水平的方法。实验实现了4μm圆形图形掩模版的复印制作,结果表明该方法可以显著提升微米级图形的掩模版复印工艺水平,降低掩模版的制作成本。     

Improvement of PMMA electron-beam lithography performance in metal liftoff through a poly-imide bi-layer system

Poly(methyl methacrylate) (PMMA) is a commonly used resist for electron-beam lithography. Some primary reasons for the widespread popularity of PMMA include high resolution and low cost. Single layer PMMA has notably poor characteristics in metal liftoff and sub-15 nm resolution as well as poor line edge roughness. Standard problems with liftoff such as tags, feature removal and lack of solvent penetration were alleviated with a poly-imide lift-off layer which increased resolution and allowed better liftoff. The effect of dense feature proximity over-dose was also reduced with this method. Single lines in metal as small as 23 nm were achieved and denser patterns were resolved with a pitch of 50 nm. These results increase the utility of PMMA as a nanolithographic material for fabricating small metallic features by the use of a liftoff technique.     

Pattern‐Transfer Fidelity in Soft Lithography: The Role of Pattern Density and Aspect Ratio

Using high‐aspect‐ratio nanostructures fabricated via two‐photon laser‐scanning lithography, we examine the deformation of elastomeric stamps used in soft nanolithography and the fidelity of patterns and replicas made using these stamps. Two‐photon laser‐scanning lithography enables us to systematically regulate the aspect ratio and pattern density of the nanostructures by varying laser‐scanning parameters such as the intensity of the laser beam, the scanning speed, the focal depth inside the resist, and the scanning‐line spacing. Two commercially available stamp/mold materials with different moduli have been investigated. We find that the pattern‐transfer fidelity is strongly affected by the pattern density. In addition, we demonstrate that true three‐dimensional structures can be successfully replicated because of the flexible nature of elastomeric poly(dimethylsiloxane).     

In situ X-ray diffraction study of self-forming barriers from a Cu-Mn alloy in 100 nm Cu/low-k damascene interconnects using synchrotron radiation

An in situ study of self-forming barriers from a Cu-Mn alloy was performed to investigate the barrier growth using X-ray diffraction on damascene lines. The associated evolution in interconnect texture and Cu stress was also observed. The shift in Cu diffraction peak position was used to determine the change in Mn concentration and hence, estimate the thickness of the MnSi_xO_y barrier. The observed peak shift followed a log(t) behaviour and is described well by metal oxidation kinetics, following the field enhanced diffusion model. We used multiple anneal temperatures to study the activation of the formation process, demonstrating a faster barrier formation with higher ion excitation. A strong [1 1 1] Cu texture was shown to develop during the anneal in contrast to traditional PVD barrier systems. Finally, the stress in the 100 nm Cu lines was calculated, observing a large in-plane relaxation when using a self-forming barrier due to reduced confinement.     

HTM技术中细微图形成形效果的衍射理论分析与实验结果

针对使用半色调掩膜技术的TFT LCD玻璃基板曝光过程中的衍射和干涉现象进行了分析.文中给出了衍射和干涉现象的理论模型,并且对这两种现象在HTM技术中所起的作用进行了解释,尤其针对不同的狭缝宽度和狭缝间距的结构进行了分析.给出了扫描电镜的图片做为进一步的说明.     

利用同步辐射光电子能谱技术研究Pb1-xSrxTe薄膜的能带移动及其组成异质结能带带阶

利用同步辐射光电子能谱技术研究了低Sr组分时Pb_(1-x)Sr_xTe薄膜能带的移动规律,并计算了Pb_(1-x)Sr_xTe/Pb Te异质结中导带帯阶所占比率.当不考虑应力时,该异质结界面导带带阶比率Qc=ΔEC/ΔEg=0.71.当考虑应力时,PbTe能带发生L能谷与O能谷的劈裂,其导带带阶比率分别为QLC=0.47和QOC=0.72.Pb_(1-x)Sr_xTe/Pb Te异质结界面具有类型Ⅰ的能带排列结构,这说明Pb_(1-x)Sr_xTe/PbTe型量子阱或量子点对电子与空穴都有较强的限制能力.该异质结能带帯阶的精确测量有利于该类三元系半导体异质结在中红外光电器件的研发和应用中发挥重要作用.     

使用区域中值滤波算法降低同步辐射红外线站由Top-Up模式引入的噪声

为了提高同步辐射红外光源的光子通量和亮度以及改善光学元件的热稳定性,同步辐射光源现多采用恒流注束(Top-Up)模式,以保持储存环内部束流的稳定.在增强器向储存环注束时,储存环电流的瞬时起伏及电子束团位置的变动等会使同步辐射红外线站所用红外傅立叶变换(FTIR)光谱仪所采的干涉图上出现较大的波动,形成噪声;本文根据该噪声的特点,以及全域中值滤波算法处理该类型的噪声的不足,提出使用区域中值滤波算法对红外谱学线站使用的FTIR光谱仪所采的干涉图进行预处理,以消除由Top-Up模式引入的噪声的影响;并根据该型噪声的特点和区域中值滤波算法的处理过程,设计了一套去除由Top-Up模式引入的同步辐射红外谱学噪声的流程,使该区域中值滤波算法的处理过程无需人工干预;使用该区域中值滤波算法对具有该型噪声的干涉图进行了降噪处理,计算结果表明:使用该滤波算法可消除由Top-Up模式引入噪声的影响,提升Top-Up模式下所采光谱的信噪比.     

Electrical and structural effects on ionizing radiation in IGFETS

In terms of initial device yield, and long term reliability, process induced radiation damage represents an area of considerable concern. The processes that need to be examined include Ion Implantation, X-ray, E-Beam and Ion Beam lithography, Electron Beam metal evaporation, Sputtering, Reactive Ion Etching, and even SEM examination. The paper discusses the effects of synchrotron X-radiation in the energy range 300-100 eV, as well as Al Ka exposures which simulate the effective wavelength of storage rings planned for X-ray lithography. It will describe such effects in the context of preliminary studies dealing with varying rad exposure level at constant gate insulator thickness, as well as the behavior at several rad exposure levels as a function of gate insulator thickness. Data will be presented indicating that despite prevailing beliefs, damage in the synchrotron range follows a linear relationship over the thickness range from less than 10 nm to 50 nm, indicating strongly that damage resides near the interface and is constant with increasing insulator thickness. It will be shown that such behavior is consistent with a simple model. Even if such damage can be annealed completely using normal techniques, which is questionable, there are wide-ranging implications concerning the rad hardness of scaled devices.