Large area and wide dimensions X-ray lithography using energy variable synchrotron radiation

We developed a new X-ray lithography system for the lithographite, galvanoformung and abformung (LIGA) process using synchrotron radiation at the New SUBARU facility of the University of Hyogo. The X-ray lithography system can utilize two different energy regions: one is a high-energy region: from 2 to 12 keV, and the other is a low-energy region from 1 to 2 keV. Each energy region can be selected in accordance with the size and shape of the desired microstructures. Large-area patterning across an A4-size area was successfully performed with a highly uniform pattern thickness. Furthermore, high-aspect-ratio patterning using a high-X-ray-energy region was also achieved using this X-ray lithography system.     

LIGA and LIGA-like processing with high energy photons

High energy X-rays, in the present case photons near 20,000 eV, can be used in LIGA-like processing. Heating problems with this type of photon flux can be avoided by proper filtration via transmission filters. The exposure of PMMA with high energy photons leads to cost effective exposures with full cost recovery estimates of $0.10 per square centimeter at 200 μm photoresist thickness. The cost advantage originates from increased PMMA absorption lengths and the ability to fabricate large area masks without diaphragms which permit large exposure fields. This work was supported in part by the National Science Foundation under grant #ECS-916566. Additional financial support via ARPA-DALP Contract ONR N00014-93-1-0911 is acknowledged. The cooperation of Dr. E. Johnson and Dr. D.P. Siddons of Brookhaven National Laboratory is gratefully acknowledged. We acknowledge the support of the staffs of the Center for X-ray Lithography, F. Cerrina, Director, and the Synchrotron Radiation, Center, D. Huber, Director, for their help and the use of their facilities. The Center for X-ray Lithography is supported by SEMATECH Center of Excellence SRC Grant No. 88-MC-507 and the Department of Defense Naval Research Laboratory Grant No. N00014-91-J-1876. The Synchrotron Radiation Center is supported by the National Science Foundation Grant No. DMR-88-21625.     

LIGA and LIGA-like processing with high energy photons

 High energy X-rays, in the present case photons near 20,000 eV, can be used in LIGA-like processing. Heating problems with this type of photon flux can be avoided by proper filtration via transmission filters. The exposure of PMMA with high energy photons leads to cost effective exposures with full cost recovery estimates of $0.10 per square centimeter at 200 μm photoresist thickness. The cost advantage originates from increased PMMA absorption lengths and the ability to fabricate large area masks without diaphragms which permit large exposure fields. Received: 30 October 1995 / Accepted: 17 January 1996     

Computation of effective regge trajectories for high energy two-body reactions

Title of program: EFFECTIVE REGGE TRAJECTORIES Catalogue number: ABCE Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland (see application form in this issue). Computer: IBM 360/67; Installation: Northumbrian Universities Multiple Access Computer, Durham, UK Operating system or monitor under which the program is executed: MICHIGAN TERMINAL SYSTEM Programming language used: FORTRAN IV High speed storage required: 46K words. No. of bits in a word: 32 Is the program overlaid? No No. of magnetic tapes required: None What other peripherals are used? Card Reader; Line Printer No. of cards in combined program and test deck: 1381 Card punching code: EBCDIC     

A new UV sensitive positive resist for X-ray masks manufacture

LIGA is a well-established process to fabricate metallic micro parts with high resolution, high precision and very low sidewall roughness by means of X-ray lithography and electroplating. The availability of a precise X-ray mask is a precondition for the final precision of the manufactured micro parts. Typical mask substrate materials, e.g. beryllium, carbon based foils, Si₃N₄ or SiC show different disadvantages such as low X-ray transparency or high toxicity or high prices or low conductivity or high thermal expansion or surface porosity causing X-ray scattering. For the fabrication of X-ray masks, PMMA with its unique features such as high aspect ratio patterns with high precision, exhibits low sensitivity and the layers preparation is not easy. SU-8, an epoxy-based UV and X-ray sensitive, chemically amplified, negative tone photoresist exhibits high aspect ratio patterns with vertical sidewalls. The difficult remove of the resist after the electroplating process significantly hinders the inspection of the fabricated X-ray mask. We present the use and suitability of an UV sensitive, chemically amplified, viscous, aqueous-alkaline developable, and easy removable positive tone photoresist, XP mr-P 15 AV, exhibiting high aspect ratio patterns with vertical sidewalls for the fabrication of X-ray masks by means of UV lithography on vitreous carbon substrates.     

Low Z substrates for cost effective high-energy, stacked exposures

 Commercial application of the “direct” LIGA process requires solving two critical issues: throughput and price. Stacking of PMMA sheets bonded to substrates and exposed simultaneously with hard X-ray has been suggested recently. This paper presents a comparison of potential low Z substrates for stacked exposures in deep X-ray lithography based on elements of the second row of the periodic table. The transmission of various substrates considered for such an application have been calculated and experimentally determined. The transmission properties of materias such a beryllium, carbon, boron and compounds are by far better than that of silicon at lower photon energies typically used in LIGA applications, but this gain decreases with increasing photon energy. In stacked exposures, however, even small gains provide significant decrease in exposure time. Received: 25 August 1997/Accepted: 3 September 1997     

A cost effective fault-tolerant scheme for RAIDs

The rapid progress in mass storage technology has made it possible for designers to implement large data storage systems for a variety of applications.One of the efficient ways to build large storage systems is to use RAIDs only when one error occurs .But in large RAIDs systems ,the fault probability will increase when the number of disks increases ,and the use of disks with big storage capacity will cause the recovering time to prolong,thus the probability of the second disk‘‘‘‘‘‘‘‘s fault will incerease Therefore,it is necessary to develop methods to recover data when two or more errors have occurred In this paper,a fault tolerant scheme is proposed based on extended Reed-Solomon code,a recovery procedure is designed to correct up to two errors which is implemented by software and hardware together,and the scheme is verified by computer simulation,In this scheme,only two redundant disks are used to recover up to two disks‘‘‘‘‘‘‘‘ fault .The encoding and decoding methods,and the implementation based on software and hardware are described.The application of the scheme in software RAIDs that are builit in cluster computers are also described .Compared with the existing methods such as EVENODD and DH ,the proposed scheme has distinct improvement in implementation and redundancy.     

高能X射线数据采集系统研究

为了克服传统的射线探测方案在高能X射线工业CT的探测与数据采集系统中的弊端,分析了高能X射线探测技术,并重点研究了高能X射线探测器——钨酸镉(CdWO4)耦合光电二极管探测器的探测原理及其信号输出特征.根据探测器信号的输出特性,研究了微弱电流信号的测量原理,详细介绍了高能X射线探测转换电路的设计,并重点介绍了微弱信号探...     

Fast prototyping of high-aspect ratio, high-resolution X-ray masks by gas-assisted focused ion beam

The capacity of chemically-assisted focused ion beam (FIB) etching systems to undertake direct and highly anisotropic erosion of thin and thick gold (or other high atomic number {Z}) coatings on X-ray mask membranes/substrates provides new levels of precision, flexibility, simplification and rapidity in the manufacture of mask absorber patterns, allowing for fast prototyping of high-aspect ratio, high-resolution masks for deep X-ray lithography for the LIGA process. In preliminary demonstrations, an automated FIB system operating at 30 keV with a gallium liquid metal source and an iodine gas injection system was used for direct milling into a few micrometer thick gold of microstructures into the sub-hundred nanometer regime. Three-dimensional micromachining in bulk diamond is also reported to illustrate the capability of the technique.This work was made possible under funding for California Institute of Technology from NASA general contract (# NAS7-1407), the partial funding for CAMD from the DARPA grant HI-MEMS Development and Manufacturing (contract # N66001-98-1-8926). Patrick Deshaye (Norsam) microsculpting work is also gratefully acknowledged.This paper was presented at the Fourth International Workshop on High Aspect Ratio Microstructure Technology HARMST 2001 in June 2001.     

Microfabrication of thick tungsten films for use as absorbers of deep X-ray lithography masks

 We fabricated thick (5 μm) tungsten (W) film patterns by sputtering and dry etching, and realized a new deep X-ray lithography mask. The X-ray mask with 5-μm-thick W absorbers could expose about 1-mm-thick resist structures. In the deposition process of W films, the column structure of about 0.2 μm grain size, from which pattern edge roughness originates, disappeared by adding nitrogen into the sputtering gas. W film etching was carried out by reducing gas pressure and cooling the substrate (−40 °C), and a side etch width of below 0.2 μm was obtained. From the results of the pattern edge roughness and the side etch width, a pattern fabrication accuracy below ±0.5 μm was achieved. Furthermore, film stress, which induces pattern distortion, was reduced to below 50 MPa by controlling the sputtering gas pressure. The obtained mask achieved a pattern distortion below ±0.3 μm. Received: 7 July 1999/Accepted: 29 May 2000     

A cost effective question-asking strategy for Horn clause systems

In many applications of knowledge based systems, the initial data are insufficient to fulfill inference. In that case, knowledge based systems ask users questions in order to acquire more information. When and what to ask is determined by a question-asking strategy. This paper deals with question-asking strategies for a Horn system in which the response costs of the questions and the probablistic estimates of the answers are given. We introduce a question sequencing rule and enhance an efficient question-asking strategy. Our computational experiments show that the proposed question-asking strategy is very effective.Supported in part by the Office of Naval Research grant N00014-94-1-0355.Supported in part by the Office of Naval Research grant N00014-95-0639.     

Fabrication of high precision X-ray mask for X-ray grating of X-ray Talbot interferometer

X-ray imaging is used in many applications such as medical diagnosis and non-destructive inspection, and has become an essential technologies in these areas. In one image technique, X-ray phase information is obtained using X-ray Talbot interferometer, for which X-ray diffraction gratings are required; however, the manufacture of fine, highly accurate, and high aspect ratio gratings is very difficult. X-ray lithography could be used to fabricate structures with high precision since it uses highly directive syncrotron radiation. Therefore, we decided to fabricate X-ray gratings using X-ray lithography technique. The accuracy of the fabricated structure depends largely on the accuracy of the X-ray mask used. In our research, we combined deep silicon dry etching technology with ultraviolet lithography in order to fabricate untapered and high precision X-ray masks containing rectangular patterns. We succeeded in fabricating an X-ray mask with a pitch of 5.3 μm. The thickness of the Au absorber was about 5 μm, and the effective area was 60  × 60 mm², which is a sufficient size for phase tomography imaging. We demonstrated the utility of the Si dry etching process for making high precision X-ray masks.     

A data mining-constraint satisfaction optimization problem for cost effective classification

We propose a data mining-constraint satisfaction optimization problem (DM–CSOP) where it is desired to maximize the number of correct classifications at a lowest possible information acquisition cost. We show that the problem can be formulated as a set of several binary variable knapsack optimization problems, which are solved sequentially. We propose a heuristic hybrid simulated annealing and gradient-descent artificial neural network (ANN) procedure to solve the DM-CSOP. Using a real-world heart disease data set, we show that the proposed hybrid procedure provides a low-cost and high-quality solution when compared to a traditional ANN classification approach.     

Discounting decision for enterprises with high fixed cost and low variable cost

Higher sales are the key to increased profit, especially for low variable cost industries. The use of quantity discount to promote business is an important way to increase sales. This study evaluates the use of discount, prepaid, multiple‐purchase credit to increase sales. The purpose is to develop a strategy to maximize the unit revenue by simultaneously determining the discount rate and utility. A numerical example and sensitivity analysis are given to illustrate the theory.     

Low cost transparent SU-8 membrane mask for deep X-ray lithography

Deep X-ray lithography masks require good transparency and mechanical resistance to the intense synchrotron X-ray beam, large active areas (cm)² and compatibility with the standard fabrication processes (optical lithography and gold electroforming). Moreover higher resolution can be achieved with low roughness flat membrane. Furthermore multiple aligned exposures require an optically transparent material. Diamond like Carbon membranes fulfill those requirements but have a prohibitive cost. Our approach consists in using an SU-8 epoxy resin layer as membrane material. In this communication the different steps of the fabrication process will be presented, as well as the results obtained using the mask for particular applications.     

A cost effective on-site fault diagnosis method for home appliance rotor failures

Microsystem Technologies - Rotating components are one of the most important machine parts used in many industrial applications. Rotating machine commonly used in homes has a washing machine, which...     

Simulation-based machine shop operations scheduling system for energy cost reduction

Owing to the ever increasing requirements in sustainability, manufacturing firms are trying to reduce their energy consumption and cost. In this paper, we propose a simulation-based machine shop operations scheduling system for minimizing the energy cost without sacrificing the productivity. The proposed system consists of two major functions: (1) real-time energy consumption monitoring (through power meters, a database server, and mobile applications) and (2) simulation-based machine shop operations scheduling (through a machine shop operations simulator). First, the real-time energy consumption monitoring function is developed to collect energy consumption data and provide real-time energy consumption status monitoring/electrical load abnormality warnings. Second, the simulation-based machine shop operations scheduling function is devised to estimate the energy consumptions and cost of CNC machines. In addition, an additive regression algorithm is developed to formulate energy consumption models for each individual machine as simulation inputs. The proposed system is implemented at a manufacturing company located in Tucson, Arizona state of USA. The experiment results reveal the effectiveness of the proposed system in achieving energy cost savings without sacrificing the productivity under various scenarios of machine shop operations.     

A two-stage model for cost effective part family and machine cell formation

This research presents, implements and tests a two-stage procedure for cost effective part family and machine cell formation. First, the problem is formulated as a mixed integer mathematical model for simultaneous machine grouping and part family assignment. This model, which we refer to as the single-stage model, considers the cost trade-offs of cell configuration, machine procurement and salvage, subcontracting, inter-cell movement, and capital investment, all of which reflect the significance of real life planning aspects. To alleviate the computational burden of this single-stage model, we decompose it into two stages: the first stage is a heuristic for machine cell and part family formations; the second stage integrates the heuristic method with a mathematical program to optimize the various cost aspects. The efficacy of the proposed models is shown through a number of example problems. The results show that the two-stage procedure is powerful in the planing stages of large-size problems where the cost aspects are crucial.     

REFiLL: A lightweight programmable middleware platform for cost effective RFID application development

Middleware platforms for RFID data filtering and collection tend to be resource intensive, costly and/or provide a low degree of programmability. In this paper, we introduce REFiLL, a lightweight middleware framework that can significantly ease the development of RFID systems. The introduced framework fits within the overall EPC global network architecture as a programmable filtering solution, sitting between the EPC (Electronic Product Code) reader virtualization layer and EPC application level events. Thanks to a set of well defined programming constructs, REFiLL renders application development a task of authoring a set of XML-based files, which are also editable within a visual development environment. Following the presentation of the REFiLL framework, we also describe the process of application development, along with sample prototype applications.     

Creating a reference database of cargo inspection X-ray images using high energy radiographs of cargo mock-ups

Customs continue to use a wide range of technology in protecting against terrorism and the movement of illicit trade and prohibited imports. The throughput of scanned vehicles and cargo increases and just keeps on growing. Therefore, the need of automated algorithms to help screening officers in inspection, examination or surveillance of vehicles and containers is crucial. In this context, the successful collaboration between manufacturers and customs offices is of key importance. Facing this topic, within the seventh framework program of the European Commission, the project ACXIS “Automated Comparison of X-ray Images for cargo Scanning” arose. The main objective of this project is to develop a manufacturer independent reference database for X-ray images of illicit and licit cargo. Historic images of real detections, images of illegal cargo mock-ups as well as images of legitimate cargo will be integrated into the reference database. For this, procedures and algorithms to uniform X-ray images of different cargo scanners was developed, as well as an automated identification method of potentially illicit cargo. Finally, these developments were incorporated in creating a training simulator and a toolbox for inspection officers enhanced X-ray screening competence.