Ultraprecision machining of polymers

71. Bandyopadhyay, B. P.; Blau, P. J. Survey of ceramic machining In Japan. Oak Ridge National Lab., TN 1993 Jul; ORNI_/M-2881.27 pages. This report is a compilation of four subcontract reports provided by B. P. Bandyopadhyay who, while a visiting professor at Toyohashi University in Japan, conducted a survey of ceramic machining technology in that country from January 1 through December 31, 1992. Various aspects of machining technology were surveyed: types of parts being produced, types of ceramic materials being used, the nature of current ceramic machining research and development, and types of machine tools. The four separate reports compiled here were originally provided in a narrative, chronological form, and some of the information has been reorganized into topical areas for this compilation. This report is organized into three sections: The first describes ten ceramic machining research and development organizations and provides a reference list of their current technical publications; the second, two major trade shows; and the third, several other products and commercial developments noted during the course of Bandyopadhyay's stay in Japan. An Appendix lists key individuals who are currently conducting ceramic machining research in Japan. 72. Matthies, T.; David, C.; Thieme, J. Trilevel reactive Ion etching processes for fabrication of 60 nm germanium structures with high aspect ratio. Journal of Vacuum Science & Technology B (Microelectronics Processing and Phenomena). 1993 Sep; The authors investigated the influence of different parameters in reactive ion etching (FILE) on the anisotropy of 60 nm test structures in a 360 nm thick layer of germanium. Structures of similar dimensions are required for zone plates in x-ray microscopy. A simple optical setup for the holographic exposure of gratings with a period of 120 nm is presented. The gratings cover an area of several mm 2. This allows for splitting of the structures perpendicular to the grating lines and successive examination of the etch profiles in a scanning electron microscope. Two different trilevel systems were developed for structuring germanium in a CBrF 3 plasma. Both trilevel systems use AZ 1350 photoresist on an intermediate layer of titanium. The bottom layer is either polyimide, which is structured by RIE in an oxygen plasma, or nickel, which is etched in a hydrogen plasma highly selective to titanium. The anisotropy of the germanium etch process has been found to increase with the ratio R of self-bias to gas pressure, whereas the selectivity decreases. The higher stability of the nickel mask allows the authors to choose higher values of R resulting in etch profiles with nearly vertical sidewalls. 73. Liu, X.; Smith, S. T.; Chetwynd, D. G. Tunneling probes for metrologlcal applications using a long-range profllometer. Review of Scientific Instruments. 1993 Nov; The construction of a long-range tunneling profilometer based on a "Nanostep" slideway is reported. This profilometer has potential capability of measuring surface profiles over a complete traverse of 50 mm horizontally and 15 p.m vertically. Its characteristics have been investigated over both long and short scanning ranges. Results are presented of a series of repeat measurements over 1.4-mm traces on a gold-coated silicon wafer. A repeatability of better than 0.2 nm is obtained and surface features of a few nanometers have been resolved laterally. Anomalies in the characteristic of tunneling current with the bias voltage are discussed in terms of surface contaminants and physical contact between tip and sample. Some problems in the application of STM in nanometric metrology are also discussed. 74. Carr, Jeffrey W.; Feger, Claudius. Ultraprecision machining of polymers. Precision Engineering. 1993 Oct; 15(4): 221-237. The single-point diamond machining of several polymeric materials has been investigated. The final surface structure and roughness of the workpiece is determined by well-established fundamentals of polymer mechanics. Material is removed via ductile, brittle, or transitional mechanisms that depend on polymer properties such as glass transition temperature, relaxation time, degree of crosslinking, and viscosity. For some materials, the mechanism could be changed from ductile to brittle with a change of operating and tool parameters. In brittle materials, the surface roughness is largely controlled by the rake face angle of the diamond. For ductile workpieces, the melt viscosity of the polymer is important. Crosslinked materials are restricted from ductile behavior by the presence of chemical bonds. As a result, material removal occurs by rupture or an extreme fracture process. With an understanding of polymer behavior, suitability of new materials for single-point diamond machining can be assessed. The change of successful processing within the operating range of the tool can be determined with a minimum number of trial and error experiments. 20 Refs. 75. Su, D.; Hall, D. R.; Jones, J. D. C. Workplece position sensing by means of a fiber optical beam delivery system. Optical Engineering. 1993 Aug; The authors report a method of measuring workpiece position in laser material processing and machining that uses a fiber optical beam delivery system. The method is based on a measurement of the power propagating in the cladding of the optical fiber in the direction from the workpiece to the laser. The power reflected from the workpiece and coupled into the cladding is shown to be a function of the position of the workpiece relative to the beam waist formed by the output optics of the beam delivery system.

The preparation of this citation list was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. W.7405-ENG-48.