Browse Prior Art Database

Spectroscopic Pitch Measurement Technique

IP.com Disclosure Number: IPCOM000036422D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Conrad, EW: AUTHOR [+2]

Abstract

This article relates to the measurement of the periodicity (pitch) of grating samples used as test sites for the purpose of monitoring critical sub-micron dimensions.

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Spectroscopic Pitch Measurement Technique

This article relates to the measurement of the periodicity (pitch) of grating samples used as test sites for the purpose of monitoring critical sub-micron dimensions.

State-of-the-art optical equipment is falling behind semiconductor manufacturing requirements for measurement of critical dimensions below 1 micron. These optical measurement tools rely on high resolution imaging capabilities to produce images of the semiconductor devices which can be calibrated and measured. The best broad band optical microscopes have a optical resolution which limits measurements to 0.7 to 0.9 micron. The newest confocal laser microscopes may be limited to measurements in the 0.3 to 0.5 micron range and are difficult to operate. Scanning electron microscopes have a resolution in the nanometer range using energetic electron beams which pose sample damage concerns. A new technique makes use of the reflected intensity of light as a function of wavelength to make pitch measurements.

Spectroscopic pitch measurements, utilizing characteristics of light reflected from an area of regular lines and spaces, can be made with a high degree of accuracy on sub-micron diffraction gratings. A

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light microscope equipped with a spectrophotometer can measure the reflected light intensity from an area of uniformly spaced lines. The spectral signal is comprised of intensities at discrete wavelengths which, when analyzed, provides a measurement...