Photomask / Direct Write Lithography Documents

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• Gate technology for 70 nm metal–oxide–semiconductor field-effect transistors with ultrathin (<2 nm) oxides

  Results are described for a gate level technology module developed to produce metal–oxide–semiconductor transistors with physical gate lengths of 70 nm and below. Lithography is performed by direct write e-beam lithography (EBL) using a thermal field-emission EBL system in SAL 601 resist. Critical dimension (CD) control, as measured by several methods, is found to depend not only on dose control but also on writing parameters such as pixel spacing. The pattern transfer using a silicon dioxide hard mask is shown to exhibit a trade-off between anisotropy and selectivity. Transmission electron microscopy cross sections reveal that two atomic layers are removed even when the gate oxide stopping layer is completely intact. We report results for gate lengths down to 60 nm with edge roughness on the order of 5 nm, within the acceptable limits for threshold requirements, while stopping the etch process on oxides as thin as 1.2 nm.
• Magneticfield Technology

  The technics of higher integration of circuits is supported by instruments of applied electron beam. The electron beam lithograph is indispensable in the mass and test production of masks and devices. The electron microscope is widely used for evaluation of wafer process as well as defects and also for measuring length.
• Fabrication of Grating Patterns by E-beam Lithography

  Along with the development of optical communication, optical integrated devices are now making rapid progress, and especially the grating, which is of a periodic structure, is now playing an important role in a wide variety of fields. In recent years, there is an increasing need for smaller grating pitches, and not only semiconductors bit also a variety of materials are used for substrates. Recently, we have established a technique to finely control the grating pitch to 1nm, less than the pattern data unit (5 nm), by E-beam (E-B) lithography. Also, the fabrication of gratings with phase shift has been simplified by changing the stage shift distance.
• Printed Media Technology for an Effective and Inexpensive Servo Track Writing of HDDs

  As an alternative method for the servo track writing of hard disk drives (HDDs), a magnetic contact duplication method by using a lithographically patterned master disk has been proposed and investigated. On the master disk, magnetic film pattern according to the information signal to be printed on slave disks is provided by a lithography technique. In this method, unlike the anhysteretic process of tile conventional contact duplication method for magnetic tapes, the master information never disappears when a large external field is applied to the master while printing. This duplication method, as we call the Printed Media technology, can provide a very effective and inexpensive lump-sum servo track writing method for HDDs.
• A thermally assisted field emission electron beam exposure system

  Electron beam lithography is widely used to fabricate densely packed devices such as high-frequency transistors, since optical lithography is unable to write the small patterns required for such devices. One major problem with micropattern writing with an electron beam exposure system, however, is slow writing speed; since the system has to write an extremely large number of patterns on low-sensitivity resist with a highly focused beam, exposure times are quite long. To speed up the writing process, we have attached a thermal field emission gun to our electron beam exposure system. This gun is designed to increase the electron source brightness and probe current density. In order to determine this new probe current density, we conducted an extensive evaluation on a complete lithography system which uses a thermal field emission gun. We have measured a current density of ~ 1000 A/cm2 at an accelerating voltage of 25 kV and conclude that this lithography system can be put to practical use in production areas requiring high throughput and submicron exposures.
• 8-Wavelength DBR Laser Array Fabricated with a Single-Step Bragg Grating Printing Technique

  An 8-wavelength DBR array for narrow channel wavelength division multiplexing (WDM) has been fabricated with a new technique for printing first-order Bragg gratings using a phase mask and a conventional incoherent source.