多机只测角无源定位中的空间对准方法

空间对准是实现多机只测角无源定位首先要解决的问题,对此,提出一种适合该应用背景的空间对准方法.该方法选择融合载机初始时刻地理坐标系作为融合中心坐标系,首先将载机在各自机体坐标系中获得的方位角转换到各自载机地理坐标系中;然后再将其转换到原点位于各载机质心、与融合中心地理坐标系平行的坐标系中,推导出方位角位于此坐标系的解析表达式.对目标来波方向、载机姿态角、各载机相对融合中心距离等因素的影响进行仿真分析,得出了各因素对空间对准过程影响的量化结论.     

Production processes and applications for the passive alignment of microcomponents

Research into structural elements for the passive alignment of microcomponents is an essential part of the framework of the collaborative research center 440 (SFB 440). For this purpose, V-groove structures for the passive alignment of cylindrical microcomponents are in a first step examined theoretically. The theoretical results are then validated by experimental testing. The use of ultra precision engineering processes, such as diamond machining, for the production of passive alignment structures is then introduced and the alignment precision of these structures is measured by the use of glass fibres representing the cylindrical microcomponents and acting as light sources for the optical observation of the alignment accuracy. In addition, these structures are compared with alignment structures which are fabricated through lithographic and micro-electroplating processes.     

Optimization of passive vibration isolators mechanical characteristics

The contribution of optimization has been essential to the more recent developments in design of new mechanical structures and materials. The objective of this work is to apply the models of material and structural optimization to the design of passive vibration isolators. A computational tool to identify the optimal viscoelastic characteristics of a nonlinear one-dimensional isolator was developed. The cost functional involves the minimization of a weighted average of the maximum transient and steady state response amplitudes for a set of predefined dynamic loads. The optimal isolator behaviour is obtained by a simulated annealing method. The solutions obtained are analyzed and discussed concerning their dependence on the applied forces and objective function selection. The results obtained can facilitate the design of elastomeric materials with improved behaviour in terms of dynamic stiffness for passive vibration control.     

A novel device of passive and fixed alignment of optical fiber

In the microoptics field, precise alignment is very important to reduce the coupling losses in optical links. In this paper, a novel device of passive and fixed alignment of optical fiber is proposed. The rectangular V-groove formed by one sidewall of SU-8 resist and the substrate is used to position the optical fiber, and the leaf spring with flexure hinge clamps it. The spring is fabricated by the sacrificial layer technique. The clamping force provided by the spring acts on the upper semi-circle of the optical fibers cross section, so that the device need not use the additional cover on the optical fiber to perform the vertical location and the final fixing. It has simple structure and process, and is convenient to assemble and integrate with other microparts. The coupling of two optical fibers using the devices in our experiment has less than 1.5 dB insert loss.     

Plasma‐beam alignment of passive liquid crystals (Invited Paper)

Abstract— A plasma‐beam process, developed for the alignment of liquid crystals (LC) in electro‐optic applications, has been successfully applied to align “non‐standard” LC, such as crystalline materials with LC phases at elevated temperatures and reactive mesogenes. In addition to the high alignment quality of the materials, there is no need for an intermediate layer between the substrate and the LC layer. Furthermore, the construction of our source simplifies the alignment procedure of large‐area rigid substrates and the roll‐to‐roll processing of flexible films. This method opens new horizons for optical retarders and polarizers, as well as anisotropic semiconducting films for organic electronics.     

A passive alignment method utilizing reference posts and its application in multi-level LIGA processing

 Many MEMS applications require multi-level microstructures in which two or more levels have to be aligned to each other in the processing. A passive alignment method based on a mechanical registration concept utilizing reference posts has been described in our early work [1]. An alignment accuracy of 1 μm for a two layers optical lithography has been achieved. In this paper the experimental results on improvement of the alignment accuracy and expanding this alignment method to multi-level X-ray or combined optical/X-ray lithography are presented. This paper was presented at the Fourth International Workshop on High Aspect Ratio Microstructure Technology HARMST 2001 in June 2001.     

无损筛选的探讨

无损筛选是当前研究常规电路与加固电路具有抗辐能力的有效方法，而无损筛选通常是指对电路最终产品进行的一种筛选。本文将以L54HC04电路研制为例，通过对其圆片级进行无损筛选试验，提出一个可以大大降低成本的无损筛选新方法－圆片级无损筛选。     

A computer assessment of the effect of hindfoot alignment on mechanical axis deviation

Lower limb malalignment is a common cause of disability that increases risk of osteoarthritis (OA). Treatment of OA may require an osteotomy or arthroplasty, which mandate accurate evaluation of mechanical loading on the limbs to achieve optimal alignment and minimal implant wear. Surgical planning uses a conventional method of mechanical axis deviation (MADC) measured from the center of the femoral head to the center of the ankle. This method fails to account for hindfoot deformity distal to the ankle. We used a computer model to compare MADC with the ground mechanical axis deviation (MADG), drawn from the center of the hip to the ground reaction point. Average anatomic measurements were analyzed with a range of knee and hindfoot angle variation in single leg stance, double leg stance, toe off and heel strike. MADG was consistently higher than MADC, suggesting a more complete estimate of weight-bearing axis that considers hindfoot deformity.     

Automatic testing of MMIC wafers

Microwave probes are used extensively for linear and nonlinear characterization of microwave devices on wafer and are commercially available for use at frequencies up to 65 GHz. An on-wafer noise measurement test system, for discrete devices, is now commercially available and on-wafer power measurement techniques are emerging slowly. These probes are also getting more recognition for the testing of packaged chips, packages, and modules. More accurate calibration techniques and their on-wafer validation are being developed. Automatic testing of MMIC wafers, using an integrated test system, is a key requirement for the development of low-cost IC production.     

Assembly of hybrid integrated micro-optical modules using passive alignment with LIGA mounting elements and adhesive bonding techniques

 Assembling hybrid integrated micro-optical modules for mono-mode applications requires alignment tolerances better than ±1 μm which, so far, were achieved by complex active alignment of the micro-optical components. This article describes a passive assembly concept employing high-precision LIGA structures to simplify assembly and reduce manufacturing costs. The advantages of this passive assembly concept are demonstrated in the micro-optical assembly of a heterodyne receiver. The micro-optical components (ball microlenses, prisms, glass fibers, photodiodes) were aligned passively by means of alignment structures made of PMMA, and were subsequently fixed by UV-curing adhesive. Photodiodes were additionally contacted with electrically conducting adhesive cured at 70 °C. The mono-mode glass fibers were mounted in fiber mounts into the fiber grooves of which the glass fibers were inserted and immobilized with UV-curing adhesive. Measurements of the optical quality of the heterodyne receiver indicated an accuracy of assembly better than 1 μm. Received: 3 January 2000/Accepted: 9 February 2000     

Modeling radiative properties of nanoscale patterned wafers

Temperature nonuniformity in rapid thermal processing of wafers is a critical problem facing the semiconductor industry. One cause of the problem is the nonuniform absorption of thermal radiation in patterned wafers where the optical properties vary across the wafer surface. This paper presents a parametric study of the radiative properties of patterned wafers, considering the effect of temperature, wavelength, and polarization. The finite-difference time-domain (FDTD) method is employed to examine the effe...     

Gold metallizations for eutectic bonding of silicon wafers

Gold eutectic bonding of silicon wafers is a good candidate for wafer level vacuum packaging of vibrating MEMS: in this paper we investigated several e-beam evaporated metallizations stacks including a titanium adhesion layer, an optional diffusion barrier (Ni or Pt) and a gold film for eutectic bonding on Si and SiO₂/Si wafers. Interdiffusion in the multilayers for annealing temperatures (380–430°C) larger than the Au–Si eutectic temperature (363°C) and times corresponding to a bonding process was characterized by RBS, roughness and resistivity measurements. Au/Pt/Ti and Au/Ti/SiO₂ were found to have the best characteristics for bonding. This was confirmed by bonding experiments.

     

Gold metallizations for eutectic bonding of silicon wafers

Gold eutectic bonding of silicon wafers is a good candidate for wafer level vacuum packaging of vibrating MEMS: in this paper we investigated several e-beam evaporated metallizations stacks including a titanium adhesion layer, an optional diffusion barrier (Ni or Pt) and a gold film for eutectic bonding on Si and SiO₂/Si wafers. Interdiffusion in the multilayers for annealing temperatures (380–430°C) larger than the Au–Si eutectic temperature (363°C) and times corresponding to a bonding process was characterized by RBS, roughness and resistivity measurements. Au/Pt/Ti and Au/Ti/SiO₂ were found to have the best characteristics for bonding. This was confirmed by bonding experiments.     

Defect detection in patterned wafers using anisotropic kernels

Wafer defect detection often relies on accurate image registration of source and reference images obtained from neighboring dies. Unfortunately, perfect registration is generally impossible, due to pattern variations between the source and reference images. In this paper, we propose a defect detection procedure, which avoids image registration and is robust to pattern variations. The proposed method is based on anisotropic kernel reconstruction of the source image using the reference image. The source and reference images are mapped into a feature space, where every feature with origin in the source image is estimated by a weighted sum of neighboring features from the reference image. The set of neighboring features is determined according to the spatial neighborhood in the original image space, and the weights are calculated from exponential distance similarity function. We show that features originating from defect regions are not reconstructible from the reference image, and hence can be identified. The performance of the proposed algorithm is evaluated and its advantage is demonstrated compared to using an anomaly detection algorithm.     

Lamb-wave microdevices fabricated on monolithic single crystalsilicon wafers

Reliable and inexpensive microdevices that can be used in physical, chemical, biological, and environmental applications are in great demand. Lamb-wave (LW) ultrasonic devices have been shown to be extremely useful for applications in liquid environments. Working LW devices have been fabricated in this investigation on monolithic single crystal membranes using well-established integrated-circuit technology. The detailed fabrication procedure, photoacoustic testing of the piezoelectric material film, and a demonstration of device performance are presented in this paper. In practice, device performance was very sensitive to the surface quality of the membrane structure. This process presents the possibility for further size reduction, increased integration, and large-scale production     

Defect cluster recognition system for fabricated semiconductor wafers

The International Technology Roadmap for Semiconductors (ITRS) identifies production test data as an essential element in improving design and technology in the manufacturing process feedback loop. One of the observations made from the high-volume production test data is that dies that fail due to a systematic failure have a tendency to form certain unique patterns that manifest as defect clusters at the wafer level. Identifying and categorising such clusters is a crucial step towards manufacturing yield improvement and implementation of real-time statistical process control. Addressing the semiconductor industry’s needs, this research proposes an automatic defect cluster recognition system for semiconductor wafers that achieves up to 95% accuracy (depending on the product type).     

Spatio-temporal alignment of sequences

This paper studies the problem of sequence-to-sequence alignment, namely, establishing correspondences in time and in space between two different video sequences of the same dynamic scene. The sequences are recorded by uncalibrated video cameras which are either stationary or jointly moving, with fixed (but unknown) internal parameters and relative intercamera external parameters. Temporal variations between image frames (such as moving objects or changes in scene illumination) are powerful cues for alignment, which cannot be exploited by standard image-to-image alignment techniques. We show that, by folding spatial and temporal cues into a single alignment framework, situations which are inherently ambiguous for traditional image-to-image alignment methods, are often uniquely resolved by sequence-to-sequence alignment. Furthermore, the ability to align and integrate information across multiple video sequences both in time and in space gives rise to new video applications that are not possible when only image-to-image alignment is used.