AVS 45th International Symposium
    Nanometer-scale Science and Technology Division Thursday Sessions
       Session NS-ThP

Paper NS-ThP4
Automated, High Precision Measurement of Critical Dimensions using the Atomic Force Microscope

Thursday, November 5, 1998, 5:30 pm, Room Hall A

Session: Nanometer-Scale Science and Technology Division Poster Session
Presenter: D.A. Chernoff, Advanced Surface Microscopy, Inc.
Authors: D.A. Chernoff, Advanced Surface Microscopy, Inc.
D.L. Burkhead, Advanced Surface Microscopy, Inc.
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Atomic Force Microscopes are used in many industries for research, engineering and process control. Until now, AFM operators have usually made dimensional measurements of sub-micron features by manually placing cursors on images or cross-section plots. Time constraints and operator fatigue limit the number of measurements. This in turn limits the extent of statistical analysis. We have developed a high accuracy measurement process which overcomes these limitations. On DVDs (Digital Versatile Discs), the smallest features are about 400 nm long, 320 nm wide, 120 nm high, with a track pitch of 740 nm. We use a specific data capture protocol and automated image analysis to measure the following parameters: track pitch@footnote 1,2,3@, bump height, bump width (at various threshold levels), bump length, and four sidewall slope angles. In a single 10x10 micron image of a DVD stamper, containing about 100 bumps, we tabulate about 1000 values. It is useful to pool the data from several images. In a plot of bump width vs. bump length, we see that width at half height increases from 315 nm for the shortest bumps (420 nm long) to about 380 nm for bumps longer than 1100 nm; this matches the increase seen for corresponding optical signals produced when a finished disc is played. Where sidewall angle deviates from the norm, we are able to review the image data to identify the specific nature of the defect. @FootnoteText@ @footnote 1@D.A. Chernoff, "Nano-metrology for the data storage industry", abstract of paper presented at AVS National Meeting 10/97, p.113 @footnote 2@US Patent # 5,644,512 and other patents pending @footnote 3@see also www.a1.com/asm