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Proceedings Paper

Supporting 256-Mb and 1-Gb DRAM mask-making requirements with the Lepton EBES4 e-beam reticle generator
Author(s): C. M. Rose; Darryl Peters; Herbert A. Waggener; David M. Walker
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Paper Abstract

Mask and reticle writing requirements for 256 Mb and 1 Gb DRAM production will place stringent demands on lithography tool capabilities. The Lepton EBES4 mask writer addresses these requirements by utilizing advanced generation e-beam technology which includes; high speed raster-scan microfigure exposure, vector-addressed major and minor deflection fields, minimum address of 15.6 nm, thermally stable metrology platform, and a high current density, high stability, long lifetime thermal field emitter. Overlay for five 6-inch masks written over a two-week period was <EQ 20 nm for MARKET arrays written in SAL605 resist at 433 MHz. The maximum deviation from an ideal grid was < 25 nm. Butting and shear errors for major (stripe) and minor (subfield) boundaries were <EQ 40 nm (mean +3(sigma) ) for patterns written in SAL605 at 400 MHz in a single pass. Overlay and butting data were not corrected for EBES4 reading precision. Image placement accuracy has been verified by reading MARKET arrays using an LMS2000 system. This level of performance for image placement accuracy, overlay, and butting are consistent with requirements proposed for 256 Mb and 1 Gb DRAM reticles. A description of the EBES4 vector-addressed, raster scanned microfigure writing scheme will be presented along with a description of the present data handling capabilities and a proposed development path to reduce data transfer time and increase throughput. The EBES4 system delivers the required edge placement resolution and accuracy for 256 Mb and 1 Gb DRAM reticles at higher throughputs than either classical raster-scan e-beam or advanced optical technologies.

Paper Details

Date Published: 3 November 1994
PDF: 8 pages
Proc. SPIE 2254, Photomask and X-Ray Mask Technology, (3 November 1994); doi: 10.1117/12.191923
Show Author Affiliations
C. M. Rose, Lepton, Inc. (United States)
Darryl Peters, Lepton, Inc. (United States)
Herbert A. Waggener, Lepton, Inc. (United States)
David M. Walker, Lepton, Inc. (United States)

Published in SPIE Proceedings Vol. 2254:
Photomask and X-Ray Mask Technology
Hideo Yoshihara, Editor(s)

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