NT-MDT Solver Next - Page 180

Solver NEXT SPM. Instruction Manual
172
To find the probe pressure on the sample, the surface of the probe-sample interaction S is
to be estimated. You can use the following equation:
2
RS ⋅= π ,
where R ≈ 10÷50 nm – is the tip apex radius.
Thus, the probe pressure on the sample can be found as:
MPamNnNSFP
z
407850/384/
22
≈==
.
In the example above SetPoint = 4 mA corresponds to the pressure of 40 MPa.
NOTE. The errors of these estimations are combined from the uncertainty of parameters
including tip curvature radius
R and stiffness coefficient k , the dependence between the
contact area and the applied force, and also from nonlinear behavior of force
Fz as a
function of the scanner displacement.
8.2.1.2. Preliminary Scanning and Selecting Lithography
Region
Before performing the force lithography, take a testing scan in a semicontact mode over
the maximum scanning area. For details on measurements with semi-contact AFM
techniques, refer to i. 7.2 on p. 84.
NOTE. For lithography, plain regions are preferable to minimize effects of landscape
features on results of lithography.
In the acquired scan, select a region for lithography. Take a scan of the selected region.
This completes preparing for force lithography. An example of the selected region image is
shown in Fig. 8-9. Scanning parameters are: scanning mode – semicontact; Mag=10;
SetPoint=5; BV=0.4 V.