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Electron Beam Scan Method for Line Width Measurements

IP.com Disclosure Number: IPCOM000049290D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Finnes, SJ: AUTHOR [+2]

Abstract

This article teaches that linewidth measurements can be made without rotating the object to be measured, and that errors in such measurements, due to angular misalignment of the object, can be eliminated.

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Electron Beam Scan Method for Line Width Measurements

This article teaches that linewidth measurements can be made without rotating the object to be measured, and that errors in such measurements, due to angular misalignment of the object, can be eliminated.

Electron-beam and X-ray lithography allow fabrication of geometries of less than 1 micrometer dimension, which strains the limits of optical tools for line- width measurement. It is known that such dimensions can be measured using electron beams, as in a scanning electron microscope (SEM). Such SEM line- width measurements have required alignment of the edges of the object to be measured with one of the scan directions of the SEM. This requires a visual judgment by the SEM operator and introduces errors in the measurement due to misalignment.

There are two common methods of aligning the wafer in the SEM for such measurements: mechanical rotation and electronic raster rotation. Mechanical rotation of the wafer is not always possible; e.g., if the measurement is to be made near the edge of a large wafer, there may not be room in the SEM chamber to rotate about the feature being measured. The use of electronic raster rotation for alignment introduces raster distortions which cause errors in the line-width measurement.

The present method, illustrated in the figure, eliminates the necessity of alignment. Two measurements are made along two orthogonal directions, e.g., the X and Y scan directions. If the two measur...