AFM issues

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Jay83
Jay83's picture
AFM issues

HI

 I am new to this forum. I hae some issues while taking some image from AFM. I am trying to get image in tapping mode.  

1. In one of my samply -it consists of nano features. While scanning in 5 micron scan size it gives the feature height 150 +/- 10 nm . But as soon as I changed the scan size to 2 micron , the feature height extracted from the cross sectional analysis become double. I could not find the reason. Please help to resole this issue.

2. While trying to scan a sample made on stain less steel substrate, I find it difficult to get an image. What I noticed is that

a> The Z centre is fluctuating greatly. Its swinging from retacted position to extended region and and it was nt possible to bring the z centre within the allowable limit by using stepper motor controller. We played with Integral gain , Scan Rate and Amplitude set point. But nothing workied.

b> While cutting the SS sample with seisures, there are some high unevenness around the edge of the sample. Is it happenning due to this? 

Looking for your valuable suggestion. 

Thanks 

Joydeep

 

NivarthiRamesh
NivarthiRamesh's picture
For your  questions, Try in

For your  questions, Try in non contact mode and cross check. the tip might be damaged.
When you try to scan something alwas make sure that the sample thickness (i mean with the substrate) is less than the standard sample supplied with the instrument. When the substarte is thick, your A-B value increases and so the tip doesn't approach the sample properly. And also the laser will not fall on the PSPD properly. Always use silver paste for fixing the substarte on the steel stub. Never use double sided tape (as it increases the height).  This might resolve your issue.

So the problem finally comes to what u r using for sticking your steel sample to the AFM stub. Also put silver paste only on the corners not inbetween your steel sample and your AFM stub.