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Title: Instrumentation for Microfabrication with Deep X-ray Lithography

Abstract

Deep X-ray lithography for microfabrication is performed at least at ten synchrotron radiation centers worldwide. The characteristic energies of these sources range from 1.4 keV up to 8 keV, covering mask making capabilities, deep X-ray lithography up to ultra deep x-ray lithography of several millimeters resist thickness. Limitations in deep X-ray lithography arise from hard X-rays in the SR-spectrum leading to adhesion losses of resist lines after the developing process, as well as heat load due to very high fluxes leading to thermal expansion of mask and resist during exposure and therefore to microstructure distortion. Considering the installations at ANKA as an example, the advantages of mirrors and central beam stops for DXRL are presented. Future research work will concentrate on feature sizes much below 1 {mu}m, while the commercialization of DXRL goes in the direction of massive automation, including parallel exposures of several samples in a very wide SR-fan, developing and inspection.

Authors:
 [1]
  1. Forschungszentrum Karlsruhe GmbH, Institut fuer Mikrostrukturtechnik, Postfach 3640, D- 76021 Karlsruhe (Germany)
Publication Date:
OSTI Identifier:
21049300
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 879; Journal Issue: 1; Conference: 9. international conference on synchrotron radiation instrumentation, Daegu (Korea, Republic of), 28 May - 2 Jun 2006; Other Information: DOI: 10.1063/1.2436339; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ADHESION; AUTOMATION; FABRICATION; HARD X RADIATION; HEATING LOAD; KEV RANGE; MASKING; MICROSTRUCTURE; MIRRORS; SYNCHROTRON RADIATION; THERMAL EXPANSION

Citation Formats

Pantenburg, F. J. Instrumentation for Microfabrication with Deep X-ray Lithography. United States: N. p., 2007. Web. doi:10.1063/1.2436339.
Pantenburg, F. J. Instrumentation for Microfabrication with Deep X-ray Lithography. United States. doi:10.1063/1.2436339.
Pantenburg, F. J. Fri . "Instrumentation for Microfabrication with Deep X-ray Lithography". United States. doi:10.1063/1.2436339.
@article{osti_21049300,
title = {Instrumentation for Microfabrication with Deep X-ray Lithography},
author = {Pantenburg, F. J.},
abstractNote = {Deep X-ray lithography for microfabrication is performed at least at ten synchrotron radiation centers worldwide. The characteristic energies of these sources range from 1.4 keV up to 8 keV, covering mask making capabilities, deep X-ray lithography up to ultra deep x-ray lithography of several millimeters resist thickness. Limitations in deep X-ray lithography arise from hard X-rays in the SR-spectrum leading to adhesion losses of resist lines after the developing process, as well as heat load due to very high fluxes leading to thermal expansion of mask and resist during exposure and therefore to microstructure distortion. Considering the installations at ANKA as an example, the advantages of mirrors and central beam stops for DXRL are presented. Future research work will concentrate on feature sizes much below 1 {mu}m, while the commercialization of DXRL goes in the direction of massive automation, including parallel exposures of several samples in a very wide SR-fan, developing and inspection.},
doi = {10.1063/1.2436339},
journal = {AIP Conference Proceedings},
number = 1,
volume = 879,
place = {United States},
year = {Fri Jan 19 00:00:00 EST 2007},
month = {Fri Jan 19 00:00:00 EST 2007}
}
  • No abstract prepared.
  • The first step in the fabrication of microstructures using deep x-ray lithography (DXRL) is the irradiation of an x-ray sensitive resist like polymethylmethacrylate (PMMA) by hard x rays. At the Advanced Photon Source, a dedicated beamline allows the proper exposure of very thick (several mm) resists. To fabricate electroformed metal microstructures with heights of several mm, a PMMA sheet is glued onto a metallic plating base. An important requirement is that the PMMA layer must adhere well to the plating base. The adhesion is greatly reduced by the penetration of even a small fraction of hard x rays through themore » mask absorber into the substrate. In this work we will show a novel technique to improve the adhesion of PMMA onto high-{ital Z} substrates for DXRL. Results of the improved adhesion are shown for different exposure/substrate conditions. {copyright} {ital 1998 American Vacuum Society.}« less
  • Deep etch x-ray lithography permits the manufacture of very accurate high-aspect-ratio microstructures, which can be used as master templates for subsequent replication by electroforming and/or molding processes. This allows for mass production of three-dimensional microstructures in a variety of materials. In this article we report on the first results using x rays from the Advanced Light Source (ALS) at the Lawrence Berkeley Laboratory, as well as on the processing and technology developed to produce high-aspect-ratio microstructures. The first masks used were simple stencil masks chemically or laser etched in thick metal sheets. For resist, we used commercial acrylic cast sheets.more » Microstructures 840 [mu]m thick were fabricated by deep x-ray lithography and used as templates for copper electroforming. A technology for the high contrast masks required to work at these short wavelengths is being developed and a deep etch x-ray lithography facility is under construction at the ALS.« less
  • The possibility of fabricating mm-wave radio frequency cavities (100{endash}300 GHz) using deep x-ray lithography (DXRL) is being investigated. The fabrication process includes manufacture of precision x-ray masks, exposure of positive resist by x-ray through the mask, resist development, and electroforming of the final microstructure. Highly precise, two-dimensional features can be machined onto wafers using DXRL. Major challenges are: fabrication of the wafers into three-dimensional rf structures; alignment and overlay accuracy of structures; adhesion of the PMMA on the copper substrate; and selection of a developer to obtain high resolution. Rectangular cavity geometry is best suited to this fabrication technique. Amore » 30- or 84-cell 108-GHz mm-wave structure can serve as an electromagnetic undulator. A mm-wave undulator, which will be discussed later, may have special features compared to the conventional undulator. First harmonic undulator radiation at 5.2 keV would be possible using the Advanced Photon Source (APS) linac system, which provides a low-emittance electron beam by using an rf thermionic gun with an energy as high as 750 MeV. More detailed rf simulation, heat extraction analysis, beam dynamics using a mm-wave structure, and measurements on 10x larger scale models can be found in these proceedings [Y.W. Kang {ital et} {ital al}., {open_quote}{open_quote}Design and Construction of Planar mm-wave Accelerating Cavity Structures{close_quote}{close_quote}] {copyright} {ital 1996 American Institute of Physics.}« less
  • Micromechanics, an emerging technology for sensor and actuator fabrication, has already been exploited in the sensor area. Progress in actuators, devices that modify their environment and are fundamentally three dimensional, has been much more modest and is suffering from the availability of a fabrication tool with the necessary attributes. If the tool is based on photoresist technology, requirements include very large structure heights: in the millimeter range, for mask-defined prismatic photoresist shapes with flanks that differ from 90 degrees by less than 15 arc-seconds. Photoresist procedures that lead to these results are very different from their counterparts in the microelectronicmore » industry. Thus, application is based on precast sheets of polymethyl methacrylate, PMMA, and solvent bonding followed by precision fly-cutting. Exposure is based on well-collimated x-ray sources, synchrotrons, with flux densities that can deposit 1,600 Joules per cubic centimeter in a finite time at the correct photoresist depth. Since PMMA has an absorption length that varies with photon energy, it is 100 micrometer at 3000 eV and increases to 1 cm at 20,000 eV, beamline and exposure designs center on transmission filters that control the low energy portion of the synchrotron spectrum. Since exposure latitude is large, overexposure by a factor of 15 is allowed, beamline and exposure design are relatively simple. Experiments via the Wisconsin machine, Aladdin, and the Brookhaven 2.6-GeV ring are being used to study the effectiveness issue of manufacturing with synchrotron radiation. Actuator test vehicles are linear and rotational magnetic micromotors with force outputs in the milli-Newton range. High energy exposures have produced large parts with submicron precision that are finding applications in ink jet printing and precision injection molding procedures. Both device types are unique to x-ray assisted processing. {copyright} {ital 1996 American Institute of Physics.}« less