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Linearity Calibration Standard for Metrology Tools

IP.com Disclosure Number: IPCOM000118627D
Original Publication Date: 1997-Apr-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 4 page(s) / 120K

Publishing Venue

IBM

Related People

Bayer, T: AUTHOR [+3]

Abstract

Disclosed is a calibration standard (Fig. 1) which allows the measuring of the linearity of profilometers, atomic force microscopes, or scanning electron microscopes with a single measurement up to a measuring range of several centimeters and with a precision of some nanometers. The calibration standard has vertical line pairs which typically have a thickness of some hundred nanometers and a height of approximately 1 &mu.m when used in an atomic force microscope.

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Linearity Calibration Standard for Metrology Tools

      Disclosed is a calibration standard (Fig. 1) which allows the
measuring of the linearity of profilometers, atomic force
microscopes, or scanning electron microscopes with a single
measurement up to a measuring range of several centimeters and with a
precision of some nanometers.  The calibration standard has vertical
line pairs which typically have a thickness of some hundred
nanometers and a height of approximately 1 &mu.m when used in an
atomic force microscope.

      Despite the high precision of the grating constant of line
gratings of known calibration standards (*), the edges of the line
grid show a significant unsharpness due to lithographically produced
edge roughness, typically in the range of 20 nm up to 100 nm.  Using
this type of calibration standards for determining the linearity of
the X-axis of an atomic force microscope requires a huge number of
measurements for statistically smoothing the edge roughness.

      Fig. 2 shows the fabrication steps for the calibration
standard.  The starting material is a silicon-on-insulator wafer,
Fig. 2a.  The "buried" oxide layer (1) provides a horizontal
reference plane for the vertical line pairs on both sides of the
vertical line pairs.  The "buried" oxide layer (1) has a thickness of
typically 0.5 &mu.m and separates the two layers (2,3) of single
crystal silicon of (100) - or (110)-orientation.  A silicon layer (3)
of (110)-orientation may be vertically etched very easily with a wet
etch step, whereas a sili...