Recent developments in dimensional metrology for microsystem components

 The PTB currently develops a special coordinate measuring machine (μCMM) for three-dimensional metrology on microsystem components. This μCMM is aimed at a measurement uncertainty of 3D-coordinates of <0.1 μm for microstructures. The instrument contains an opto-tactile sensor and a new tactile 3D-micro-sensing system. The 3D-micro probe is based on a silicon boss-membrane with piezo resistive transducers which allow measuring deflections of the probe pin and simultaneously forces in three dimensions. First 2D-probing experiments with a stiff commercial stylus, 15 mm long, with a 300 μm ruby ball have been carried out showing its resolution and repeatability. Received: 30 May 2001/Accepted: 15 October 2001     

New generation of microsystem simulators

A novel type of microsystem simulator is described which allows a system designer to tailor the simulator to his application. Simulation of I/O, real-time events, and additional hardware (which may contain other processors) is possible, which is not the case for most existing simulators.     

The effect of residual solvent on the profiles of thick positive DNO-photoresist for microsystem technologies

To fabricate microstructures with heights between 10 and 100 μm and smallest structural dimensions of several micrometers optical lithography is widely used. In this case positive photoresists of the DQN-type together with contact printing have been used by various groups to produce templates for electroplating. A common feature of the resist processes described in the literature is a concave resist profile with the narrowest part at approximately 2/3 of the resist height. As the structure width becomes smaller, the vanishing of this neck determines the smallest structures that can be obtained. This corresponds to a maximum aspect ratio of about 6. Within a model for the resist development based on percolation theory, a quadratic dependence of the dissolution rate on the solvent concentration is postulated in the theoretical section. The solvent concentration may be measured by weighing samples before and after baking and the overall content may be varied by different baking times in the range between 10 and 25%. The measurement of the average dissolution rate qualitatively supports the quadratic dependence postulated by the theory. A depth resolved measurement of the dissolution rate shows a significantly reduced rate in the top 1/3 of unexposed resist which suggests that the solvent content in the top 1/3 is drastically reduced. Based on the model, a detailed discussion of various experimental effects of thick DNQ-resists follows. In particular, the dried surface of the resist is made responsible for the concave resist profile in the top parts while near the substrate details of exposure dose, resist bleaching and diffraction need to be taken into account. In view of fabricating microstructures using DQN-resists with a high aspect ratio near 10 and vertical sidewalls, the baking as well as resist performance and exposure optics will have to be optimized.     

Interface modelling of microsystem interconnections using micropolar theory and discontinuous approximation

The contribution focuses on the application of micropolar theory to establish a model for prediction of the interface behavior in microsystem adhesive interconnections. As the dimension of the adhesive itself is usually much smaller than that of neighboring components, and still may include internal structures, the interconnection is treated as an interface zone with an underlying microstructure. The micropolar theory is used in the vicinity of the interface to model the transfer of the couple stress across the interface, and a micropolar continuum is used to model the interface across which a displacement and a rotational jump are regularized on the basis of the adopted discontinuous kinematics. The resulting elastic interface model picks up the influence of the micro-structure on the basis of an intuitive definition of the stiffness coefficients. The paper is concluded by some numerical examples focusing on a typical interconnect. A parametric study is carried out to reveal the micropolar effect with respect to the size of the micro-structure.     

Micro-machining processes for microsystem technology

By means of experiments it could determined that micro-machining processes as grinding, drilling and milling are a good addition to the established production technologies in micro technology. To machine hard and brittle materials grinding with diamond tools is well suitable, but the kinematics of the grinding process, as well as the process strategy has a significant influence on the machined surface quality and the chipping of the edges. The study of micro-machining processes showed, that micro cutting processes are not just a miniaturisation of the conventional cutting technology. The reduced tool stiffness of micro drills caused by the changes of geometry requires an adjustment of the complete drilling processes. Sharp cutting edges are an essential requirement for the fabrication of very small structures. So, using single edged micro milling cutters made of diamond significant smaller structures could be made compared to using conventional milling cutters made of tungsten carbide. Furthermore, acoustic emission sensors proved to be suitable for detecting the tool position after a change of the tool with a high accuracy.     

High-energy density miniature thermoelectric generator using catalytic combustion

This paper describes the components and system of a thermoelectric (TE) generator with a catalytic butane combustor. The combustion chamber with a size of 8 mm/spl times/8 mm/spl times/0.4 mm is etched in a 0.65-mm-thick silicon substrate, and bonded to both sides of a 0.77-mm-thick glass substrate with a thin-film ignition heater. A set of 34 couples of BiTe TE elements, each with a size of 0.65 mm/spl times/0.65 mm/spl times/2 mm, are directly bonded to both sides of the combustor. The combustor without the TE modules was tested using butane as fuel, and self-sustaining combustion and electrical ignition were achieved. Also, nearly 100% combustion efficiency and a uniform temperature distribution were confirmed by gas chromatography and infrared thermoimaging, respectively. When the TE modules were attached to the combustor, however, butane combustion was impossible. The characteristics of TE generation were measured using hydrogen as fuel. When a theoretical combustion power was 6.6 W, the maximum output power of 184 mW was obtained with a load of 5.68 /spl Omega/. The total efficiency in this experiment was 2.8% (184 mW/6.6 W).     

智能文本搜索新技术

面对当今互联网上海量的信息,以及搜索信息准确、高效、个性化等需求,提出了一套包括信息检索、信息抽取和信息过滤在内的智能文本搜索新技术.首先举荐了与信息检索新技术相关的企业检索、实体检索、博客检索、相关反馈子任务.然后介绍了与信息抽取技术相关的实体关联和实体填充子任务,以及与信息过滤技术相关的垃圾邮件过滤子任务.这些关键技术融合在一起,在多个著名的国际评测中得到应用,如美国主办的文本检索会议评测和文本分析会议评测,并且在互联网舆情、短信舆情和校园网对象搜索引擎等实际系统中得到了检验.     

Frontside micromachining using purous-silicon sacrificial-layer technologies

Several electro- and photo-electrochemical processes are pointed out which allow silicon microstructures to be formed within ion-implanted silicon wafers. It is shown how different lateral and vertical doping profiles can be used to anodize selectively parts of the ion-implanted silicon wafers, creating isolated regions of porous silicon. After removal of the porous silicon in diluted KOH, micromachined structures emerge at the front surface of the silicon wafers which entirely consist of low-stress bulk crystalline silicon.     

New monitor technologies are on display

Imagine portable smart screens that can connect wirelessly with a base PC from anywhere in a house or small office; thin, flexible displays that roll up like paper for transport or storage; or monitors with onscreen circuitry that function like self-contained computers. These are, in fact, just a few of the newest developments currently taking place in computer display technology. Except for a few exotic approaches that have emerged occasionally, display technology has essentially been the same for many years. But researchers are already developing a number of innovative display approaches that could improve the user's experience, reduce energy consumption, and, in some cases, alter the way people work with computers. The paper discusses organic light-emitting diode (OLED) displays, also known as organic electroluminescent (OEL) displays.     

Remote rendering solutions using web technologies

Remote rendering is a well-known solution to the issue of running high-performance applications requiring complex visualizations on less capable hardware/software platforms or when client access to the data source for visualization is undesired or prohibitive in terms of required bandwidth. Visualizing the output of these remote rendering applications is typically achieved through native applications or, when considering a browser environment, through plug-ins. In this paper, several solutions are presented that enable deployment of these applications on standard web browsers, even those from the pre-HTML5 era. The focus in this paper is on two specific use case scenarios, taking into account that the proposed solutions are generic enough to be applied to a range of similar applications. The technologies presented cover the entire range of sub-processes contained in a complete remote rendering solution, such as the establishment of interaction feedback channels and delivery of images as part of the rendering pipeline. Depending on factors such as application requirements, developer preferences, feature availability in the web browser or raw performance figures, a custom solution can be composed from the options discussed in this paper. This is illustrated by applying them to the two aforementioned use cases, each with specific requirements and challenges, and benchmarking these example setups in terms of performance. A comparison of advantages and disadvantages is presented to guide developers in applying the technologies under real-life conditions.     

New trends on e-Procurement applying semantic technologies

The present editorial note introduces the concept of e-Procurement and the use of semantic technologies to improve some of the processes involved in electronic purchasing processes. Currently there is a growing interest to boost the use of electronic communications to deal with Business-to-Business (B2B), Business-to-Consumer (B2C) or Administration-to-Administration (A2A) relationships. New technologies are emerging with the aim of: (1) reducing costs; (2) providing more intelligent environments to make decisions in more timely and accurate fashion and (3) improving the overall efficiency of business processes. More specifically, e-Procurement defined as the business to business purchase and sale of supplies over the Internet can be found in a variety of ways from public marketplaces involving many firms to private exchanges that are currently facing a challenging environment to migrate from paper-based systems to an electronic ecosystem. However several interlinked challenges to achieve a successful transition have been identified such as lack of interoperable and standard-based infrastructures (data and services), legal uncertainties including the necessity of improving trust, privacy and provenance of data and information and lack of transparency, accessibility or usability to name a few. In this context semantic-based technologies arise to afford a common and standard data model that eases the interoperability, integration and creation of knowledge-based systems. Taking into account the necessity of a more interoperable and intelligent system to manage e-Procurement processes and the emerging application of semantics in different domains, this special issue is intended to provide researchers, developers and practitioners a summary of the current status of e-Procurement applying semantics.