Olympus BL-AC40TS-C2 Podręcznik użytkownika - Strona 3

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Tetrahedral tip in two stage structure

The tip profile is symmetric with a half tip angle of 18 degrees macroscopically (see left below).

The side tip profile is asymmetric with a tip angle of 35 degrees. When the cantilever chip is

attached to a chip holder in your AFM with an angle, about 10 degrees, the asymmetry is

improved (see right below).

Scan line profile

Front view

A two stage structure is employed in this probe.

(see left illustration)

The head of the probe tip is made of silicon and

tetrahedral in shape. The foot of the probe tips is

also made of silicon, but covered with a silicon

nitride film.

There is a discontinuity in the probe shape

midway between base and apex. The measurable

sample height therefore limited to the height of

the tip (3.5 micron).

As can be seen in the left illustration,

a tetrahedral tip is located near the triangular end

of the cantilever. When observing the cantilever

from the reflex side, a triangular pocket can be

seen near the free end of the cantilever, marking

the base of the tetrahedral tip. Operators can

therefore easily locate the tip position relative to

samples under optical microscope observation by

finding the center of the triangular pocket. This

makes alignment of the tip with sample very easy

in AFMs, combined with optical microscopes.

Scan line profile

Side view

- 5e -

The apex of the tetrahedral tip becomes sharper due to an oxide sharpening process. The tip

angle in the final few hundred nano meter of the apex, is about 15 to 25 degrees (see below).

When you set your samples to your instrument, please consider the unique shape of the

tetrahedral tip, that is 'good symmetry', when viewing from front side and choose the direction

of the sample. When measuring long grooves, you can get an idea of what angle of the cut will

be quickly by aligning the cantilever along the grooves and scanning across at right angles

against grooves (see below).

Trouble-shooting guide

Situations as described below may arise when using this type of cantilever.

Case 1: I tried optimizing imaging parameters first in air before. However good parameter

values cannot be found and the cantilever oscillated.

Solution:

From the beginning, try to optimize the measurement condition in water,

optics, cantilever sensitivity, I-gain, P-gain and frequency tuning.

Selecting a smaller oscillation amplitude of cantilever for AC mode AFM measurement

may gives better images because the tip is sharp and the cantilever is shorter than

conventional cantilevers.

e.g

., sensor

- 6e -