Forums
Bruker Media
Community Media
Bruker AFM Probes
SPM Digest
Application Notes
NanoTheater
Website
中文
Brochures & Datasheets
Publications
Probes Catalog
Events
Manuals & Documentation
Presentations
Guide to AFM Modes
News
Journal Club
Webinars & Video
Nanovations
Other
I would like to use a TESP-SS tip as well as a high aspect ratio tip purchased from another manufacturer (CNT-FM, 2.8 N/m, 150 kHz, carbon nanotube, from Nanosensors) with ScanAsyst. Do you have any strategies for using ScanAsyst with these fragile tips as these cantilevers are not ideal for ScanAsyst?
Hi Tony,
While I have not yet tried using PeakForce Tapping or ScanAsyst with CNT probes, I don't think that there should be any problem... we have used PFT with a wide variety of probes, from the standard soft ScanAsyst probes up to very stiff indentation probes to interrogate QNM properties on very hard samples. For CNT tips, I would suspect that you would like to minimize the forces as much as possible... Ideally, the CNT probes would be mounted on much softer levers to minimize the interaction forces... at 2.8N/m, it is certainly worth trying the CNT-FM probes and seeing how they perform.
My suggested strategy for working with these probes (or any new probe) would be to engage with the ScanAsyst auto-setpoint control disabled (you can still leave the gain control enabled). Engage on your sample with the scan size set to 0, and with the initial force setpoint set to a small initial value (e.g. 0.02V)... make sure that you can see the force curves in the force monitor, ensuring that you are on the surface with the feedback on the surface working properly. I would think that the adhesion forces would be relatively small with a CNT probe, indicating that the contact area between the probe and the surface is small. If the force curves look nice, you can start to scan slowly (e.g. 1Hz on 1um) and see if you can track surface features while still applying the low force.
Please keep us updated to your success - we'd love to hear how it goes!
Best regards,
Adam
Tony,
I don’t think you should have any problem using these probes, and the operation should not change. A key feature of ScanAsyst is its exceptional force control when compared to other modes, and we have found that this force control enables much higher resolution when imaging because tip sharpness can be maintained preserved and better and longer. (Also, with the auto optimization of ScanAsyst you do not have to worry about parameters.)
I should note almost all silicon probes are manufactured with apex’s much sharper than what one typically obtains with conventional imaging. In these cases, going to SS tips does not help because they are immediately damaged upon engage. . .careful operation can help this, but even so, the imaging forces are more than with ScanAsyst. Below is data comparing tip wear between Tapping and ScanAsyst. As you can see the ScanAsyst controlled tip, after many images, remains sharper that of, Tapping after 1 image!
Why do you think you need to go to SS Probes? I would expect the ScanAsyst air probes, with the sharp Si tip and low k, to give you better results anyway. . .
Steve
I need to be able to image poly-Silicon grain boundaries and characterize, as much as possible, the depth of the boundary. Thus, I require a very sharp and high aspect ratio tip. The CNT and SS tips seemed to hold the best promise for accomplishing this daunting task.
I think that you may find that ScanAsyst Air probes may work just as well, and at significantly lower cost. The aspect ratio of ScanAsyst Air probes are fairly high for the last 70 or 80nm of the probe's height, certainly plenty for to get deep into the poly-Si grain bounderies... and while the spec for tip radius on ScanAsyst Air probes is <10nm, some of these probes come out as extrememly sharp, some <2nm. A CNT probe will definiitely have ROC <2nm... but at a such a significantly higher cost ($775 for 2 CNT-FM probes, vs $275 for a box of 10 ScanAsyst Air). If you do a comparison of imaging performance, of course we would love to see your results.
Thank you for your responses. I will try the ScanAsyst tips as you suggest.
A basic question. How would you define a "good looking force curve"?? Also, does Nanoscope IIIa have this ScanAsyst feature ??
The NanoScope IIIa does not have this feature - ScanAsyst works with Peak Force Tapping mode on the NanoScope V controller... although many of the older systems can be upgraded.
Peak Force Tapping makes a force curve measurement at each pixel as the primary feedback mechanism. It directly controls the interaction force between the tip and sample. As such, having a "good force curve" is required for the mode to operate properly. ScanAsyst enables automatic SPM feedback optimization, controlling the setpoint and gains.