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Special Tips for the 3-D Scanning Force Microscopy

IP.com Disclosure Number: IPCOM000113218D
Original Publication Date: 1994-Jul-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 100K

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Bayer, T: AUTHOR [+4]


Disclosed are special tip shapes for profiling slopes with overhang profiles and methods for their production.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Special Tips for the 3-D Scanning Force Microscopy

      Disclosed are special tip shapes for profiling slopes with
overhang profiles and methods for their production.

      One of the key components of a scanning force microscope is a
fine tip, mounted on a cantilever which acts as a spring and
transforms force variations between tip and surface into measurable
displacements of the cantilever.

      Originally, only cone shaped tips have been used, f. e. with
tip/cantilevers made of single crystal silicon (EP 0413040).  When
profiling vertical structures, cone shaped tips cannot access the
vertical side walls.

      The problem is described in Fig. 1a and 1b, where a vertical
profile with a top overhang and a "stack" structure with protrusions
of the middle layer is shown.

      A tip is proposed, which has a similar overhang (a tenth of
micron larger) as the structure to be profiled.  With such a tip one
can profile the shape of the overhang and can measure the distance of
the overhang.

      One cannot use one generic headed tip to solve all measurements
problems in measuring overhang profiles.  The overhang itself, the
opening in the overhang structure (Fig. 1a) and the depth of the
structure have to be accomodated by an adequate headed tip.

      The tip itself has physical limitations, mainly with respect to
tip shaft stiffness.  As a rule of thumb, the tip shaft (Fig. 2)
should not exceed an aspect ratio of 5 up to 10 (length to diameter)
in order to be stiff enough for van der Waals force mode of
operation.  Proposed is a headed tip, mounted on a shaft, mounted on
a pedestal, mounted on a cantilever, where tip head, tip shaft, tip
pedestal can be of one, two or three different materials.  It is
important that tip head, shaft diameter and length and pedestal
height and length can be "customized" easily to the measurement

      Fig. 2a shows a version, where all components consist of single
crystal silicon, but the tip head consists of heavily p+-doped single
crystal silicon.

      Fig. 2b shows a version, where cantilever and pedestal consist
of single crystal silicon, the shaft of a different material (f.e.
silicon dioxide) and the tip head of a third material (f.e.  silicon