Veeco 004-210-000, Instruction Manual, Page: 233 / 358

Force Imaging
Force Modulation with ‘Negative LiftMode’
Rev. B MultiMode SPM Instruction Manual 213
11.7 Force Modulation with ‘Negative LiftMode’
A new form of force modulation imaging utilizing TappingMode and LiftMode operation known as
“Negative LiftMode,” allows imaging of certain materials previously not visible with Contact Mode
AFM force modulation. This method is especially suited for softer materials, yielding higher
resolution. Best results using negative LiftMode are obtained on relatively smooth samples (<
500nm vertical features); however, Veeco encourages experimenting with this technique on
rougher surfaces as well. A general procedure for Force Modulation with “Negative LiftMode” is
described in
Section 11.7.3 .
Note: Force modulation contrast is very sensitive to the spring constant of the tip,
which varies according to the length and thickness of the cantilever. You may
perform TappingMode easily with either force modulation or TappingMode
cantilevers, but you may have dif
fi culty with Contact Mode AFM silicon and
silicon nitride cantilevers (see Table 11.6a ).
1. Verify the probe is withdrawn from the sample surface.
2. Switch modes under Microscope > Profile to TappingMode .
3. Verify in the Main Controls panel that SPM Feedback = Amplitude .
11.7.1 Set Interleave Controls
In the Interleave Controls panel (select Panels > Interleave to open it if it is not open), set the
following
1. Click the Enable buttons next to the Drive frequency and Drive amplitude parameters;
when enabled the buttons appear green.
2. Set the Drive amplitude on the Interleave Controls panel to 200 - 400mV .
3. Set the Drive Frequency on the Interleave Controls panel to the bimorph resonant
frequency found in Section 11.6.4 .
4. Set Lift start height and Lift scan height to 0.00nm .
5. For now, set the Interleave mode parameter to Disabled .