Browse Prior Art Database

Atomic Precision Standard

IP.com Disclosure Number: IPCOM000101284D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 76K

Publishing Venue

IBM

Related People

Mueller, RP: AUTHOR [+2]

Abstract

This article describes a new method and apparatus to provide a mechanically and physically stable measurement standard, the function of which is based on the "tunneling microscopy" principles. The tunneling microscope is based on extreme proximity of a needle-like structure to a test surface, the application of a 1-5 V field voltage, and the generation of a tunneling current formed due to electrons leaving the tip and entering the test surface. The tip is scanned across the test surface under investigation using X-Y piezoelectric rods. The tunneling current is adjusted by a third piezoelectric rod the Z piezo, placed orthogonally to the X-Y pair. A servo system is used to maintain the tunneling current constant during the X-Y scan of the test surface under investigation.

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Atomic Precision Standard

       This article describes a new method and apparatus to
provide a mechanically and physically stable measurement standard,
the function of which is based on the "tunneling microscopy"
principles.  The tunneling microscope is based on extreme proximity
of a needle-like structure to a test surface, the application of a
1-5 V field voltage, and the generation of a tunneling current formed
due to electrons leaving the tip and entering the test surface.  The
tip is scanned across the test surface under investigation using X-Y
piezoelectric rods.  The tunneling current is adjusted by a third
piezoelectric rod the Z piezo, placed orthogonally to the X-Y pair.
A servo system is used to maintain the tunneling current constant
during the X-Y scan of the test surface under investigation.  While
monitoring the changes in the Z axis piezo, via a voltage detection
at the piezo unit, a graph can be obtained which is proportional to
the structure of the surface under study.  Atomic features can thus
be observed.

      The measurement standard disclosed is based on the electron
tunneling effect summarized above.  It includes in an evacuated,
mechanically-coupled structure, a 001 silicon surface, a tip and a
compressible mechanism.  Referring to the figure, a metallic cavity
10 is equipped with a deformable platen 12 similar to the structure
used in the construction of aneroid barometers.  On the platen 12 is
connected a mechanical shaft 14 restricted in its motion to one
degree of freedom.  A fine tip 16 is mounted on the shaft 14.  The
tip 16 is placed at tunneling distance d from a single crystalline
surface 18 of known orientation and characteristics (i.e., 001
silicon single crystal). The single crystalline surface is mounted on
a piezo unit 20 operating on t...