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Journal of Vacuum Science & technology B: Microelectronics and Nanometer Structures processing, Measurement, and Phenomena 1992年第6期10卷 2890-2892页

作者： R. A. Ghanbari M. Burkhardt D. A. Antoniadis Henry I. Smith M. R. Melloch K. W. Rhee M. C. Peckerar Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02139 School of Electrical Engineering Purdue University West Lafayette Indiana 47907 Nanoelectronics Processing Facility U. S. Naval Research Laboratory Washington DC 20375

We report on measured Hall mobility versus temperature for high‐quality modulation‐doped AlGaAs/GaAs samples after exposure by electrons and x rays at doses and energies typically used in lithography. We find that bare samples exposed by 50 keV electrons suffered significant mobility degradation over the temperature range of 4.2–300 K (as much as a factor of 30). X‐ray‐exposed samples did not show any mobility degradation. Two‐dimensional electron densities were not dramatically affected by either exposure technique, although e‐beam exposed samples did show a slight decrease in carrier density. Our results are consistent with previous reports of mobility degradation in some e‐beam evaporators.

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Conductance quantization in a GaAs electron waveguide device fabricated by x‐ray lithography

Journal of Vacuum Science & Technology B: Microelectronics a...

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Journal of Vacuum Science & technology B: Microelectronics and Nanometer Structures processing, Measurement, and Phenomena 1992年第6期10卷 2966-2969页

作者： W. Chu C. C. Eugster A. Moel E. E. Moon J. A. del Alamo Henry I. Smith M. L. Schattenburg K. W. Rhee M. C. Peckerar M. R. Melloch Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02139 Center for Space Research Massachusetts Institute of Technology Cambridge Massachusetts 02139 Nanoelectronics Processing Facility U.S. Naval Research Laboratory Washington DC 20375 School of Electrical Engineering Purdue University West Lafayette Indiana 47907

We report on the fabrication of AlGaAs/GaAs split‐gate electron waveguide devices of lengths between 0.1 and 2 μm using x‐ray lithography, and the measurements of these devices at liquid‐helium temperatures and up to 15 K. An x‐ray mask (parent mask) was fabricated using e‐beam lithography and replicated using proximity x‐ray lithography (λ=1.32 nm) to generate a replica (daughter) mask. The daughter mask was then aligned to patterns on a high‐mobility AlGaAs/GaAs sample and x ray exposed using a conformable mask fixture. The conductance of the electron waveguides was measured as a function of the split‐gate bias. Sharp 2e2/h conductance steps were observed in devices up to 0.75 μm long at T=2 K. The features in the conductance remain visible up to 15 K.

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Fabrication of parallel quasi‐one‐dimensional wires using a novel conformable x‐ray mask technology

Journal of Vacuum Science & Technology B: Microelectronics a...

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Journal of Vacuum Science & technology B: Microelectronics and Nanometer Structures processing, Measurement, and Phenomena 1992年第6期10卷 3196-3199页

作者： R. A. Ghanbari W. Chu E. E. Moon M. Burkhardt K. Yee D. A. Antoniadis Henry I. Smith M. L. Schattenburg K. W. Rhee R. Bass M. C. Peckerar M. R. Melloch Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02139 Center for Space Research Massachusetts Institute of Technology Cambridge Massachusetts 02139 Nanoelectronics Processing Facility U. S. Naval Research Laboratory Washington DC 20375 School of Electrical Engineering Purdue University West Lafayette Indiana 47907

We report on the fabrication of quasi‐one‐dimensional wires on modulation‐doped GaAs/AlGaAs using a novel conformable x‐ray mask technology which allows us to expose arbitrary sized samples, including samples much smaller than the membrane area, using our laboratory’s standard 31 mm‐diam silicon‐nitride x‐ray mask. After optical alignment, the sample and mask are brought into contact electrically, and then loaded into a specially designed cartridge which allows a vacuum to be pulled between mask and substrate. The vacuum causes the x‐ray mask to conform around the sample. We find that a vacuum hold down is necessary to allow easy separation of the sample from the mask with minimal risk to both.

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Holographic moiré patterns processed by the fourier transform method

Holographic moiré patterns processed by the fourier transfo...

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Holographics International 1992

作者： Simova, Eli S. Stoev, Krassimir N. Central Laboratory of Optical Storage and Processing of Information Bulgarian Academy of Sciences P.O. Box 95 Sofia1113 Bulgaria Institute of Nuclear Energy and Nuclear Research Bulgarian Academy of Sciences Boul. Trakia 72 Sofia1784 Bulgaria Electrical Engineering Department University of Ottawa 161 Louis Pasteur OttawaONKIN 6N5 Canada River Road Environmental Technology Center 3439 River Road GloucesterONK1 A 0H3 Canada

Spatial-carrier fringe pattern analysis is a wide-spread technique and has found a lot of applications to optical metrology. Introducing spatial-carrier into a holographic moire pattern is also a well-known technique to obtain observable moire fringes. Preprocessing of the holographic moire pattern includes optical or digital Fourier filtering to remove the carrier. The fringe pattern is then processed by using time-consuming fringe-counting algorithms. The current work presents a new appUcation of the Fourier transform method to automated analysis of holographic moire fringe patterns. The method owns the advantage of instantaneous determination of both phase functions in the pattern. Investigations are carried out on the frequency restrictions imposed on the phase functions. The technique is demonstrated on computer generated noisy holographic moire patterns. The technique does not compUcate the conventional experimental holographic moire arrangement. © 1992 SPIE. All rights reserved.

关键词： Moire fringes

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IMAGE SEQUENCE CODING BY SPLIT AND MERGE

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IEEE TRANSACTIONS ON COMMUNICATIONS 1991年第12期39卷 1845-1855页

作者： WILLEMIN, P REED, TR KUNT, M Signal and Image Processing Laboratory Swiss Federal Institute of Technology Lausanne Switzerland Department of Electrical Engineering and Computer Science University of California Davis CA USA

This paper describes a method for reducing the information contained in an image sequence, while retaining the information necessary for the interpretation of the sequence by a human observer. The method consists of first locating the redundant information, reducing the degree of redundancy, and coding the result. The sequence is treated as a single 3-D data volume, the voxels of which are grouped into several regions, obtained by a 3-D split and merge algorithm. To find these regions, we first obtain an initial region space by splitting the image sequence until the gray-level variation over each region can be approximated by a 3-D polynomial, to a specified accuracy. This results in a set of parallelepipedic regions of various sizes. To represent the gray-level variation over these regions, the coefficients of the approximating polynomial are used as features. The most similar regions are then merged, using a region adjacency graph. The information is coded by representing the borders of the regions using a pyramidal structure in the x, y, t space. The coefficients of the approximating polynomials are coded in a straightforward manner. For 256 x 256 pixel, 25 frames/s image sequences, compressions allowing transmission rates near 64 kbit/s are obtained.

关键词： Image sequences Image coding Pixel Bandwidth Layout Polynomials Image segmentation Humans Helium ISDN

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Axial radio frequency electric field intensity and ion density during low to high mode transition in argon electron cyclotron resonance discharges

Journal of Vacuum Science & Technology B: Microelectronics a...

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Journal of Vacuum Science & technology B: Microelectronics and Nanometer Structures processing, Measurement, and Phenomena 1991年第2期9卷 339-347页

作者： D. A. Carl M. C. Williamson M. A. Lieberman A. J. Lichtenberg Department of Chemical Engineering Plasma Assisted Materials Processing Laboratory Univerity of California Berkeley California 94720 Department of Electrical Engineering and Computer Sciences Plasma Assited Materials Processing Laboratory University of California Berkeley California 94720

To investigate the transition from the low density mode to the high density mode in an electron cyclotron resonance (ECR) discharge, a Langmuir probe and an E field probe were used to measure ion density and E field intensity as functions of axial position and power. The experiments were performed in argon at 0.13 Pa in a 7.9 cm diam cyclindrical source chamber propagating TE11 mode 2.45 GHz microwave power. Low mode was characterized by a standing wave throughout the plasma chamber and minimal power absorption. High mode exhibited nearly complete power absorption and no standing wave past the ECR zone. A sliding short (ss) was used to determine if the position of an E field null in the source chamber affected the transition between these two modes for various magnetic field configurations. The ss position had little effect on mode transition, relative power absorption or ion density when positioned downstream from a broad, large volume resonance zone (resonance near the mirror midplane). However, the plasma could not be ignited if the short was placed at or upstream from the large volume resonance *** the magnetic field was adjusted to yield a sharp, small volume resonance zone (resonance midway between the midplane and the throat), then positioning the ss to force an E field null at the resonance zone would prevent plasma ignition, even at 800 W forward power. The ion density exhibited a hysteresis (i.e., a direct jump from no plasma to a plasma density observed at other sliding short positions for that same forward power, thereafter following the ion density versus forward power dependence observed at nearby ss positions) on power cycling when the sliding short was within ∼1 cm of the broad resonance zone or within ∼1 cm of forcing a null in the sharp resonance zone caes. The ion density versus power curve for the broad volume case exhibited a change in slope over the transition region (Pforward ≊40 W) when the ion density at the resonance zone was ≊1×1011 cm

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Design of a system for software testing and debugging for multiprocessor avionics systems 15

Design of a system for software testing and debugging for mu...

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15th Annual International computer Software and Applications Conference, CMPSAC 1991

作者： Lumpp, James E. Shultz, Roger K. Casavant, Thomas L. Parallel Processing Laboratory Department of Electrical and Computer Engineering University of Iowa Iowa CityIA52242 United States Advanced Technology and Engineering Collins Commercial Avionics Rockwell International Corporation Cedar RapidsIA52498 United States

ISBN: (纸本)0818621524

The debugging and testing of commercial software constitutes a substantial portion of the development time and, by most estimates, over fifty percent of the overall cost of software development. For critical applications, such as avionics, complete testing is extremely important. However, as multiprocessor software solutions find their way into these critical applications as a means of increasing performance and reliability, the need for both debugging and testing tools increases dramatically. This paper focuses on the gathering of accurate run-time information providing support for both debugging and testing of embedded multi-processor systems by employing runtime identification of "simple events" and post-execution identification of "compound events." Additionally, we propose a novel way of combining specification based (black-box) system testing and automatic monitoring to substantially reduce the complexity, tedium, and cost of complete structural (white-box) testing. © 1991 IEEE.

关键词： Program debugging

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Patterning tungsten films with an electron beam lithography system at 50 keV for x‐ray mask applications

Journal of Vacuum Science & Technology B: Microelectronics a...

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Journal of Vacuum Science & technology B: Microelectronics and Nanometer Structures processing, Measurement, and Phenomena 1991年第6期9卷 3292-3296页

作者： K. W. Rhee A. C. Ting L. M. Shirey K. W. Foster J. M. Andrews M. C. Peckerar Y.‐C. Ku Nanoelectronics Processing Facility Electronics Science and Technology Division Naval Research Laboratory Washington DC 20375 Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02139

The application of electron beam lithography for the fabrication of x‐ray masks is essential in the development of x‐ray lithography technology. In this paper we present experimental results on the patterning of submicron (2–0.25 μm) features into a single‐layer negative e‐beam resist and then subsequent transfer of these patterns onto a 0.4 μm‐thick tungsten film by reactive ion etching. To study the dependence of the proximity effect on the substrate material, a comparison of linewidths and sidewall profiles of electron beam resist images on silicon, silicon dioxide on silicon, and tungsten on silicon wafers has been established.

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Reformulation of Chang's criterion for the absence of limit cycles using bilinear transform

Reformulation of Chang's criterion for the absence of limit ...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： T.C. Macedo T. Laakso P.S.R. Diniz I. Hartimo Department of Electrical Engineering Federal University of Rio de Janeiro (COPPE-EE) Rio de Janeiro Brazil Laboratory of Signal Processing and Computer Technology Helsinki University of Technology Espoo Finland

A procedure for the reformulation of Chang's criterion (1981) for the absence of zero-input limit cycles in recursive digital filters is presented. The technique employs the standard bilinear transform to convert a frequency-domain criterion into a polynomial form in terms of matrix transformations. The use of the method is illustrated with design examples applied to determine the stability region for certain single-quantizer recursive filter structures. The results can be utilized, e.g., in the design of an error feedback network for a given filter such that limit cycles are eliminated.< >

关键词： Limit-cycles Feedback Digital filters Stability criteria Paper technology Difference equations Frequency conversion Matrix converters Finite wordlength effects Adaptive filters

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Design of a system for software testing and debugging for multiprocessor avionics systems

Design of a system for software testing and debugging for mu...

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IEEE Annual International computer Software and Applications Conference (COMPSAC)

作者： J.E. Lumpp R.K. Shultz T.L. Casavant Parallel Processing Laboratory Department of Electrical and Computer Engineering University of Iowa Iowa IA USA Advanced Technology and Engineering Collins Commercial Avionics Rockwell International Corporation Cedar Rapids IA USA

As multiprocessor software solutions find their way into critical applications such as avionics as a means of increasing performance and reliability, the need for both debugging and testing tools increases dramatically. The authors focus on the gathering of accurate run-time information providing support for both debugging and testing of embedded multiprocessor systems by using run-time identification of simple events and postexecution identification of compound events. Additionally, they propose a way of combining specification-based (black-box) system testing and automatic monitoring to substantially reduce the complexity, tedium, and cost of complete structural (white-box) testing.< >

关键词： Software testing System testing Software debugging Software performance Software tools Application software Aerospace electronics Runtime Multiprocessing systems computerized monitoring

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