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Line and Trench Measurement with an SFM Optimized Optical Sensor

IP.com Disclosure Number: IPCOM000104138D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Martin, Y: AUTHOR

Abstract

Cross-sectional measurement of line and trench profiles, including accurate measurement of width, becomes a increasingly important task in the field of micro-metrology. Accurate micro-metrology is carried out primarily with SEMs (Scanning Electron

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Line and Trench Measurement with an SFM Optimized Optical Sensor

      Cross-sectional measurement of line and trench profiles,
including accurate measurement of width, becomes a increasingly
important task in the field of micro-metrology.  Accurate
micro-metrology is carried out primarily with SEMs (Scanning Electron

Microscope), although with many disadvantages such as the need for
vacuum, profiling with cross-sectioning only gives the profile at one
location of the line, groove or trench and is time consuming, and
limited spatial accuracy results due to spurious effects from e-beam
interaction with the material.

      The  accuracy of a line-width measurement critically depends on
the accuracy in sensing (or imaging, or profiling) the side walls of
the line.  Requirements for micro-metrology and micro-profiling are
often similar.  The Scanning Force Microscope [1]  is a potential
candidate for meeting these requirements.  Its success comes from the
capability to accurately sense the position of a surface, using fine
microscopic tips with specific shapes [2], which can now be
manufactured in a reproducible way.

      In one proposed version of the instrument described in [3], the
tip is vibrated at two mechanical resonances, horizontally and
vertically, in order to sense a surface of arbitrary angle,
horizontal or vertical.  The measurement of the tip vibration is
achieved by using two heterodyne interferometers [4], having their
laser beam focused on top and on the side of the cantilever which
holds the tip.  This solution significantly increases the complexity
of the SFM apparatus since it requires aligning and focusing two
separated beams on the small cantilever.

      A greatly simplified solution is to measure the two vibrations
using one optical beam, focused on top of the cantilever, but
positioned at the edge of it....