Ocean Optics NanoCalc - Manual (Page 61)

Ocean Optics Germany GmbH Thin Film Metrology
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In automatic mode it is NOT necessary to add values for the upper and lower estimate.
You should give reasonable values for these limits in fitting mode as this influences the time for calculation
considerably.
9.1.6 Fixed limits
If you fix a layer you force the upper and lower limit to have the same value as the thickness value. This
means that the thickness of a fixed layer is regarded to be “well-known” = exact.
Example: thickness = 500 nm
upper limit = 500 nm
lower limit = 500 nm
NanoCalc_1 is able to analyze even 3 layers if two of them are “well-known” = fixed.
The same applies to 2 layers: one of them has to be fixed and the other may be analyzed. It is of no
importance which layer is to be analyzed.
NanoCalc_10nk can extract 2 or 3 layers simultaneously. Of course this takes some time...
9.1.7 Narrow Limits
If you click “narrow limits”, NanoCalc uses rather narrow low and
high limits range of about 100 nm above and below your
thickness estimate (depending on the material of the layer)
Example1: thickness = 500 nm
upper limit = 600 nm
lower limit = 400 nm
Example2: thickness = 3500 nm
upper limit = 3600 nm
lower limit = 3400 nm
If you need a larger range of limits you have to choose the options
WideLimits or UserLimits (up to 300000 nm).
9.1.8 Wide Limits
To use this option you should consult the menu EditStructure \ Setup first:
You have the choice between relative and absolute wide limits
If you choose “wide limits mode” (e.g. ±1000 nm and a thickness of 4000 nm), NanoCalc will search between
3000 nm and 5000 nm.
9.1.9 User limits
If you click “user limits”, NanoCalc accepts your values for lower and upper limits (up to 300000 nm = 300
micrometers).