MT-compatible laser-ablated interconnections for optical printed circuit boards

Integration of optical interconnections on a printed circuit board (PCB) is very challenging, since compatibility should be maintained with standard PCB manufacturing technology. This paper describes the use of laser ablation, a technique already used in PCB manufacturing for drilling microvias, as a suitable technique for the fabrication of multimode polymer waveguides, micromirrors, alignment features, and microlenses. A frequency-tripled Nd-YAG laser and a KrF excimer laser are used, both mounted on the same stage, resulting in very high alignment accuracies. This paper demonstrates a parallel optical link over approximately 5-cm-long PCB integrated waveguides, fully connected using a standard MT-based connector. This proves that laser ablation can be a key technology in optical board manufacturing to reach the stringent coupling tolerances.     

Neural network-based real-time malfunction diagnosis of reactive ion etching using in situ metrology data

To mitigate capital equipment investments and enhance product quality, semiconductor manufactures are turning to advanced process control (APC) methods. With the objective of facilitating APC, this paper investigates a methodology for real-time malfunction diagnosis of reactive ion etching (RIE) employing two types of in situ metrology: optical emission spectroscopy (OES) and residual gas analysis (RGA). Based on metrology data, time series neural networks (TSNNs) are trained to generate evidential belief for potential malfunctions in real time, and Dempster-Shafer (D-S) theory is adopted for evidential reasoning. Successful malfunction diagnosis is achieved, with only a single missed alarm and a single false alarm occurring out of 21 test runs when both sensors are used in tandem. From the results, we conclude that the OES and RGA sensors, in conjunction with the TSNN models, can be effectively used for RIE monitoring and diagnosis. Furthermore, D-S theory is shown to be an appropriate inference methodology.     

Automated malfunction diagnosis of semiconductor fabricationequipment: a plasma etch application

A general methodology for the automated diagnosis of integrated circuit fabrication equipment is presented. The technique combines the best aspects of quantitative algorithmic diagnosis and qualitative knowledge-based approaches. Evidence from equipment maintenance history, real-time tool data, and incline measurements are integrated using evidential reasoning. This methodology is applied to the identification of faults in the Lam Research Autoetch 490 automated plasma etching system located in the Berkeley Microfabrication Laboratory     

高聚物生物芯片材料激光加工性能分析

用准分子激光对高聚物材料进行微加工制作,可以获得比较理想的高聚物基生物芯片。根据对制作生物芯片材料的性能要求,比较了聚甲基丙烯酸甲酯(PMMA)和聚碳酸酯(PC)对不同波长激光的光波透过率,测量了高聚物材料经准分子激光加工后的微结构,并得出准分子激光对不同材料的刻蚀速率与入射激光能量密度之间的关系。结果表明,PMMA和PC都能够完全吸收KrF准分子激光能量,可以用准分子激光在表面进行微加工制作生物芯片;用PMMA制作出的生物芯片,在使用时对检测结果的质量影响比PC小;对于相同的入射激光能量密度,准分子激光对PMMA的刻蚀率比PC高;由于与准分子激光之间的反应机理不同,PMMA更容易被加工,但是加工后的微结构质量较PC差。     

准分子激光加工PMMA生物芯片片基的实验研究

用准分子激光对高聚物材料进行微加工制作,可以得到比较理想的高聚物基生物芯片。采用248nm的KrF准分子激光器对PMMA(聚甲基丙烯酸甲酯)进行微细加工,探讨了准分子激光与PMMA相互作用的机理。进行了表面微通道制作和打孔实验,研究激光加工的工艺参数及加工质量的变化规律。结果表明,准分子激光蚀刻完全适合生物芯片的制作,而且加工过程简单,是一种行之有效的制作方法。     

准分子激光与角膜组织的相互作用及在屈光矫正中的应用

准分子激光在屈光手术中获得了迅速发展，193nm的准分子激光刻蚀角膜表面，改变角膜表面的光学结构从而矫正屈光不正，而且由于其微小的力学和热效应，不会损伤邻近组织。本文研究了激光和生物组织的相互作用，定性确定了光斑与角膜表面粗糙度关系，定量分析了193nm准分子激光高斯光束的切削量与能量密度的关系，在此基础上，给出准分子激光应用到眼科治疗机中的原理图、屈光程度与激光消融量的关系和具体算法，最后通过PMMA板的实验验证，并已应用到临床，取得了良好的效果。     

准分子激光切削角膜机理及其应用

本文研究了准分子激光屈光手术的原理、切削机理、角膜切削方式的选择、准分子激光切削量与能量密度的 关系、“飞点扫描”技术。并在此基础上研制了准分子激光眼科治疗机,经过临床应用,取得了满意的手术效果。     

The via squeeze

Already less than 150 μm in diameter, vias can no longer be economically produced by mechanical drilling, as are conventional throughholes. Instead, they must be made by such alternative processes as laser ablation or the photochemical etching of thin dielectrics built up on either side of a conventional circuit board core. The new microvias are electrical paths less than 0.1 mm in diameter running between one layer of the circuit board structure and another. The first major change in the technology in 30 years, microvias are gaining momentum and pushing the printed-circuit industry to use new materials and new processes     

193nm准分子激光飞点扫描角膜的研究

本文详细叙述了 193nm准分子激光切削角膜屈光矫正的几种治疗模式 ,并以近视加散光为例 ,对准分子激光消融角膜量的数学模型进行了定量的推导。研究了准分子激光切削角膜的机理 ,提出了确定角膜切削所需的激光脉冲的数目和脉冲位置的方法。在此基础上研究了准分子激光飞点扫描的几种算法 ,并进行了相应的临床实验 ,通过比较得到了两种较好的飞点扫描算法 ,现已在手术中使用。     

Fabrication of microvias for multilayer LTCC substrates

Advances in screen printing and photoimageable paste technologies have allowed low-temperature cofired ceramic (LTCC) circuit densities to continue to increase; however, the size of vias for Z-axis interconnections in multilayer LTCC substrates have been a limiting process constraint. In order to effectively exploit the 50-100-/spl mu/m line/spacing capabilities of advanced screen printing and photoimageable techniques, microvia technologies need to achieve 100 /spl mu/m and under in diameter. Three main steps in fabrication of microvias include via formation, via metallization or via fill, and layer-to-layer alignment. The challenges associated with the processing and equipment for the fabrication of microvias are addressed in this paper. Microvias down to 50 /spl mu/m in diameter with spacings as small as 50 /spl mu/m are achieved in 50-254-/spl mu/m-thick LTCC tape layers through the use of a mechanical punching system, whereas the minimum size of 75-/spl mu/m via/spacing is obtained using a pulse laser-drilling system in the LTCC tape layers with the same thicknesses as those for the punching test. The quality of punched microvias and laser-drilled microvias will be presented as well. Layer-to-layer alignment is crucial to the connection of vias in adjacent LTCC tape layers. Through a stack and tack machine with a three-camera vision system and an adjustable precision stage, less than 25-/spl mu/m layer-to-layer misalignment is achieved across a 114.3/spl times/114.3 mm (4.5/spl times/4.5 in) design area. In a six-layer LTCC test substrate (152/spl times/152/spl times/0.762 mm), microvias of 50, 75, and 100 /spl mu/m in diameter are successfully fabricated without the use of via catch pads. The cross section of fired microvias filled with silver conductor pastes at various locations of this substrate demonstrates a minor layer-to-layer misalignment in both X and Y directions across the substrate.     

193nm准分子激光及超短脉冲激光角膜切削

193nm准分子激光和费秒级超短脉冲激光因其能对角膜进行精确的切削 ,对临近组织造成的损伤很小 ,已经成为屈光手术领域研究的热点。本文首先研究 193nm准分子激光 ,费秒级超短脉冲激光对角膜的切削机理 ,建立激光脉冲参数与角膜组织切削量之间的数学模型并在此基础上对比分析两种激光切削角膜的特征及其在屈光手术领域的应用。     

准分子激光消融兔前列腺的实验研究

报道了使用ＸｅＣｌ准分子激光（３０８ｎｍ）照射兔前列腺标本。观察了在不同频率、不同介质等条件下对离体免前列腺组织的消融效果，测得损伤阈值为４００ｍＪ／ｃｍ２。结果表明，准分子激光具有消融效果高、对周围组织损伤轻、损伤范围易于控制等特点，具有实际临床应用的价值。     

激光烧蚀Al表面溅射Al正离子的平动能分布测定和机理研究

用柱面镜离子能量分析器测定了准分子激光烧蚀Al靶产生的Al~+和Al~(2+)离子的平动能分布,Al~+离子平动能分布主要由二组离子构成,最可几平动能分别为15eV和50eV,较高平动能组离子的产生有一个激光通量阈值,大约为0.9J/cm~2,对产生两组离子的不同机理进行了研究和讨论。     

激光微孔加工技术在印刷线路板生产中的应用

在印刷线路板(PCB)加工业中，微孔加工技术一直是制约该丁业发展的主要因素之一，人们对体积小、功能强、性能稳定的产品需求不断推动这项技术的发展。介绍了激光技术在微孔加工方面的应用，阐述了微孔加工的机理、设备、工艺方法及所涉及到的PCB板材料。     

Excimer-laser ablation and etching

The characteristics of excimer lasers and the nature of ablation and etching processes are described. The two kinds of laser ablation mechanisms, thermal and electronic, are discussed. Thermal processes all rely on an intense laser pulse to heat a surface very rapidly. Electronic mechanisms do not rely on heating. Two of these quantum-type processes have been discussed widely. In the first, laser photons directly excite and break the bonds of the solid, causing ejection of material. In the second, photoexcitation creates electron-hole pairs, the potential energy of which can be coupled directly into kinetic energy of the atoms via a radiationless process. The energized atoms are able to overcome the surface binding energy, and again material is ejected. Pulsed laser etching has many of the same physical-interaction mechanisms as laser ablation but requires an active chemical medium to be in contact with the solid because laser-induced chemical reactions serve as the driving force for material removal. Issues that must be addressed prior to the successful implementation of an excimer-laser fabrication tool are discussed. The use of patterned beams for direct patterning of surfaces is considered. Microelectronic applications suitable for excimer-laser ablation and etching are examined     

准分子激光微加工技术结合模塑技术加工微流控芯片

利用准分子激光微加工技术与模塑技术相结合的方法制造微流控芯片。用准分子激光在玻璃基胶层上刻蚀出加工质量较高的微流控生物芯片形貌,通过电铸技术对微流控芯片进行复制,得到反向金属模具。用金属模具通过注塑成型技术用聚碳酸酯注塑出微流控芯片。系统研究了准分子激光的能量密度和工作台移动速度对胶层微通道加工质量的影响;测量并分析了激光刻蚀加工出的微流控芯片原型、电铸的反向金属模板和注塑成型后的微流控芯片的轮廓精度和表面粗糙度,上表面尺度偏差不大于2μm,底面粗糙度小于20 nm。对注塑出的微流控芯片和激光直写刻蚀的几何结构相同的微流控芯片的流动性能进行比较测试。在流速较小时,用激光微加工技术与模塑技术相结合的方法加工的微通道比准分子激光直写法所加工的微通道流动性能更好。     

Modeling and optimization of via formation in dielectrics by laser ablation using neural networks and genetic algorithms

Laser ablation is an effective process for forming vias in dielectric layers during the fabrication of multilayer substrates in microsystems packaging. In this paper, vias with diameters of 10-50 /spl mu/m are ablated in DuPont Kapton E polyimide using an Anvik HexScan 2150 SXE excimer laser operating at 308 nm. A statistical experiment employing a 2/sup 5-1/ fractional factorial design is conducted to determine the significance of laser fluence, shot frequency, number of pulses, and the vertical and horizontal positions of the debris removal system on the ablated thickness of the dielectric, top via diameter, via wall angle, and via resistance. Resistance measurements on metal deposited in ablated vias are performed to characterize via quality. Neural networks (NNs) are trained using the error back-propagation algorithm to model the ablation process using the measurement data collected from the experiment. Genetic algorithms are then utilized in conjunction with the NN models to derive optimized process recipes for achieving target responses. The recipes identified are subsequently verified by experiment. These optimized recipes are found to improve ablation results by as much as 40% for the ablated film thickness, 30% for via diameter, 9% for via wall angle, and more than 100% for via resistance.     

Laser transfer of sol-gel ferroelectric thin films using an ITO release layer

A new laser transfer process is reported which allows damage-free transfer of ferroelectric thin films from a growth substrate directly to a target substrate. The thin film ferroelectric material is deposited on a fused silica growth substrate with a sacrificial release layer of ITO (indium tin oxide). Regions of the film that are to be transferred are then selectively metallised, and bonded to the target substrate. Separation from the growth substrate is achieved by laser ablation of the ITO release layer by a single pulse from a KrF excimer laser, with the laser light being incident through the growth substrate. The residual ITO on the transferred ferroelectric layer is electrically conducting, and may be suitable for incorporation into the final device, depending on the application. The new process has been demonstrated for 500 nm-thick layers of sol-gel PZT which were thermosonically bonded to a silicon target substrate prior to laser release. The transferred films show ferroelectric behaviour and have a slightly reduced permittivity compared to the as-deposited material.     

激光去除光纤涂敷层的实验研究

采用波长为10. 6μm的TEA CO2 红外激光和波长为248nm的KrF准分子激光去除SMF28光纤涂敷层,研究了激光脉冲能量密度和脉冲数与涂敷层去除效果之间的关系。实验 证明,涂敷层去除厚度随激光脉冲能量密度的增加呈对数增长,随红外激光脉冲数的增加呈对数变化,随紫外激光脉冲数的增加呈线性变化,且去除效果在红外激光8.15J / cm2、20个脉冲和紫外激光452mJ / cm2、800个脉冲下达到最佳。     

193nm准分子激光切削角膜的研究

193nm准分子激光对角膜的消融机理是眼屈光性手术如LASIK和PRK中的重点问题.首先分析两种描述193nm准分子激光对角膜的消融机理的模型:光蚀除模型和光物理模型,得出能量密度与角膜切削深度的关系.并且研究影响屈光手术效果稳定性与可预见性的因素,在此基础上优化激光的扫描算法.研究结果直接应用于准分子激光屈光矫正系统,在实际应用中取得了很好的效果.