Polyester film imaging parameters

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DavidBell Posted: Wed, Apr 6 2011 5:50 AM

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I am beginning a study on Polyester films with AFM. I am currently trying to optimise my scanning parameters and tip specifications to suit imaging in tapping mode at all magnifications and resolutions from 100um down to 500nm.

I would welcome any opinions on cantilever stiffness, thickness, resonant frequency, drive amplitude, tip architechture and material etc...

Many Thanks David (D3100 user)

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replied on Wed, Apr 6 2011 11:25 AM

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Hi David,

TESPA and FESPA are good starting choices for your application. Tune them slightly to the left of resonance with a target amplitude of 300-500mV. This should get you going.

If you download the Bruker AFM probes catalog you will find on pages 46-50 tables of typical applications and the suggested probes. The catalog can be found here:

http://www.brukerafmprobes.com/documents/bruker_atomic_force_microscopy_probes_and_accessories_catalog.pdf

Best,

Stefan

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DavidBell replied on Thu, Apr 7 2011 3:20 AM

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Thanks Stefan,

That drive amplitude seems a little excessive though! I normally image between 70mV and 300mV. When a tip exceeds this its usually a sign that its nearing end of its lifetime.

I was more curious about what people thought about Silicon vs Silicon nitride, resonant frequency, stiffness, and what kind of supersharp probes are best for high mag polyester film imaging, DLC, supersharp silicon etc

Any thoughts?

Thanks

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replied on Thu, Apr 7 2011 11:49 AM

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Hi David,

Did you have a chance to look at the table in the brukerafmprobes catalog? Page 46 has a list of tips/materials for various applications including polymer imaging.

http://www.brukerafmprobes.com/documents/bruker_atomic_force_microscopy_probes_and_accessories_catalog.pdf

In general, for TappingMode silicon probes are used. The two most common ones are probably FESP(A) and TESP(A). The FESPs being a bit softer and thus having a lower resonance frequency. FESPs can be a bit more forgiving as they are softer and often give a slightly better phase signal. TESPs are stiffer and thus can be operated at lower amplitudes as they do not tend to snap down to the surface. The tips on these probes are quite sharp and I do not think you need any "supersharp" variants for your films.

My suggestion to get started was the "target amplitude" and not the "drive amplitude", i.e. use whatever drive that results in a target of 300-500mV. If you find of course that you get better data at different settings use it.

Stefan