三轴离子束抛光系统驻留时间算法

在光学离子束抛光工艺中,驻留时间求解是一个关键问题。多数驻留时间求解算法要求离子束在工件表面的材料去除速率在加工过程中保持不变。然而,离子束在工件表面的材料去除速率与离子束入射角度有关。为此,在加工曲面工件时,通常采用精密五轴联动运动平台对离子源的运动及姿态进行实时控制,使得在加工曲面工件时离子束相对工件表面的入射角度始终保持不变,从而保证去除函数在整个离子束抛光过程中保持不变。提出了一种基于仿真加工的迭代驻留时间求解算法,在求解驻留时间的过程中考虑到入射角度带来的去除速率变化,从而使得在离子束抛光系统中只需采用三轴运动控制平台对离子源的运动进行控制,而不再需要对离子源的姿态进行实时控制。入射角度与去除速率曲线可以事先通过实验测得。与五轴运动平台相比,三轴平台更稳定、经济且易于控制。仿真结果表明,算法在三轴离子束抛光系统中具有较好的适用性。     

AT切型石英晶圆抛光工艺对材料去除速率及厚度非均匀性的影响

通过双面抛光工艺研究了抛光盘转速、抛光盘压力及抛光垫材质与厚度等对AT切型石英晶圆材料去除速率(MRR)与厚度非均匀性(TNU)的影响。实验结果表明,抛光盘压力越大、转速越高,材料去除速率越高;晶圆厚度非均匀性随抛光盘压力增加先减小后增加,随抛光盘转速增加而增加;杨氏模量越大、厚度越薄的抛光垫在晶圆表面产生的压力分布越均匀,有助于提高抛光均匀性。最后基于上述实验结果对抛光工艺参数进行了优化,优化后晶圆的材料去除速率为0.9μm/h、单片晶圆厚度非均匀性小于1.5‰、表面粗糙度为0.6 nm。该研究结果适用于石英晶圆的批量抛光工艺,对石英晶圆加工企业的抛光工艺优化有较高的参考价值。     

大口径导光板抛光及其功率谱密度分析

光学技术对于现代科学尤其是航天科学的发展起着越来越重要的作用。而具有高精度大口径光学元器件的跨尺度加工一直是现代光学技术的难点。超精密气囊抛光技术是基于计算机控制光学表面成形技术。其采用充气的柔性抛光气囊作为抛光工具,解决了传统数控抛光方法中抛光头不能很好地和工件吻合的缺点。以Preston方程为基础,研究了超精密气囊抛光的理论材料去除特性,建立了气囊抛光中进动运动方式下的材料去除模型,并针对气囊抛光工具的物理特性,按照Hertz接触理论对去除模型进行了修正。在理论分析的基础上完成了一块口径为570 mm的平面楔形工件的抛光,使得工件的面形精度P-V值达到了1/8 ,RMS值达到1/75 。并分析了该元件的功率谱密度（PSD）曲线,窄带噪声及其产生原因。     

精密数控抛光碳化硅表面去除特性研究

计算机数控精密机械抛光技术是制造高精度、高质量光学元件表面的主要技术之一。然而,对于碳化硅材料表面去除特性方面的研究却相对较少。在航天航空领域中,陶瓷类材料碳化硅的应用较为广泛。针对计算机数控精密机械抛光技术,根据一系列的抛光实验,研究并总结出碳化硅材料表面的去除机理。基于选择不同等级的四种变量参数:抛光磨头转速、抛光压力、磨头补偿量和抛光头角度,分析碳化硅材料表面的去除趋势。采用Taguchi方法可以有效优化实验设计参数、减少实验整体次数。结果表明:文中总结出对应的抛光参数组合和材料表面的去除特性,确保加工出高质量表面的碳化硅材料。     

基于椭圆运动方式的小工具抛光去除函数

为了改进传统的小工具抛光的去除函数的特性和提高去除效率,在行星和平转动抛光方式的基础上,通过三转子机构,实现了椭圆式运动方式;以Preston理论为基础,研究并推导了在这种运动方式下的材料去除函数;通过计算机模拟得到了去除函数的面形矩阵,经过优化后获得了最终的抛光参量,得到了与理想的高斯型函数吻合程度高的去除函数。结果表明,仿真加工后,其去除效率优于行星式去除函数。基于椭圆运动方式的小工具抛光避免了行星和平转动抛光方式去除函数存在的缺陷,有助于提高抛光过程的去除效率。     

大口径光学元件精密加工温差分析及控制方法

针对大口径光学元件精密加工时上下表面存在温差的问题,以环形抛光系统为例,对抛光盘和工件温度特性进行了研究。在1.6m环形抛光机上对工件温度进行了测定,结果表明即使在低速抛光情况下工件上下表面也会产生较大的温差。提出了合理搭配工艺参数和对工件非加工面绝热两种温差控制方法。通过采用控制变量法和对工件绝热抛光法进行测温实验验证了方案的可行性,为高精度面形加工奠定了基础。     

液体喷射抛光技术研究

液体喷射抛光(FJP)技术是近几年提出的一种新型光学抛光工艺,本文简介了这种抛光技术的原理,介绍了我们的研究结果,其中包括在抛光机理方面提出抛光液中磨料粒子的径向流动对工件产生的径向磨削剪切作用是材料去除的关键;建立了较完善的描述FJP过程的数学模型;提出了获得较理想工作函数的方法;得到了求解时间驻留函数的一种算法;另外还研究了不同FJP溶液及一些工艺参数对样品表面粗糙度的影响、被抛光材料特性对材料去除率及表面粗糙度的影响等.结合这些研究建立了一套非球面数控液体喷射抛光没备和相关工艺,并利用其对实际非球面做了数控抛光实验,最后得到其截面的误差优于0.15靘PV,表面粗糙度Ra达到2.25nm,实验结果表明此技术可用于非球面的数控抛光.     

红外光学用Ge双面抛光片抛光工艺条件研究

分析了不同抛光条件下,Ge双面抛光片的表面状况,通过抛光压力、抛光液中氧化荆的比例、抛光机转速和转速比等条件的改变,阐述了这些因素对抛光速率、抛光片正反面质量的影响,得到了相应的关系图表.根据实验结果,确定了Ge双面抛光工艺条件,采用该工艺条件对Ge片进行双面抛光,抛光片的几何参数指标和表面质量均能满足红外光学应用对抛光片的要求.     

基于田口方法的合金薄膜铜衬底超精密抛光工艺优化研究

为了获得性能优良的电化学沉积合金薄膜,需要精度非常高的合金薄膜铜衬底.以铜衬底表面粗糙度Ra和Rt为评价目标,探讨了基于田口方法的铜衬底抛光工艺参数优化设计方法.在给定工件材料和磨料(种类和粒度)的条件下,加工载荷、磨料浓度和加工速度是影响铜衬底抛光表面质量的主要工艺参数.运用田口方法进行了实验设计,并通过对实验结果的分析,得出了最佳的抛光工艺参数组合,采用该实验条件进行加工获得了非常光滑的铜衬底表面(Ra 6 nm,Rt 60 nm),表明田口方法能够有效的应用于铜衬底抛光工艺参数的优化设计和分析.     

超薄硅双面抛光片抛光工艺技术

MEMS器件、保护电路、空间太阳电池等的制作需要使用硅双面抛光片,并且要求抛光片的厚度很薄,传统的硅抛光片加工工艺已经不能满足这一要求.介绍了一种用于超薄硅单晶双面抛光片加工的抛光工艺方法.通过对硅片抛光机理[1],抛光方式、抛光工艺的研究和对抛光工艺试验结果的分析,解决了超薄硅单晶双面抛光片在加工过程中碎片率高、抛光...     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.