There are some causes for shift an image in SEM:

- charging of sample's surface. Do you examine conductive samples? 

- mechanical vibrations. You can make a simple experiment: kick a floor when scanning, you will see some distortions on the image;

- effect of an external electromagnetic fields;

- problems with software (incorrect noise reduction algorithm);

Good luck! 

In addition: if you use double sided carbon tape/tabs you can have image shift at higher magnifications because of specimen movements. You may check if it is true by using superglue.

Most probably you are imaging non conductive sample - just do the fast scan mode with the lowest beam intensity you can do an image and use accumulations.

Or your sample is badly sticked to the sample holder and the glue or carbon tape is moving the sample (by enlarging the volume) - try different fixation or just fix more

Or sample is too heavy and need some more fixation - fix it properly

Or your stage is not well connected to the ground - search in manual how the stage should be connected

Cheers!

Next to sample charging and improper mounting, there are also two other reasons for image shift/ sample drift. When moving the SEM stage, the stage mechanics needs some time to get into stable state. The sample also is heating up when interacting with the beam. In order to bring the sample and the stage in an equilibrium state, the following approach can minimise the sample drift and enhance the measurement time for EDS element mapping:

Mounting the sample with silver paint also provides a stronger bond when compared to double sided carbon tape.

To all above I would like to add that the problem of the image shifting in SEM can be not correctly exhibited Aperture Diaphragm.

Yus Prasetyo, could you attach an example of image here?

If you are imaging non-conductive specimens, charging can be minimized with imaging at acceleration voltages below a certain value or above a certain other value. 

Non-conductive specimens have secondary to primary electron ratio higher than unity for a certain range of acceleration voltages. 

Dear All,

Thank you very much for the answer, actually this is my first question trough RG, surprised that many people are answering.

I'm metallurgist, mainly my sample was metal that mounted (resin-hardener), even tough sample was coated wit Au-Pd for quite long time (120s), the image shifting still happen especially above 10k.

Valdimir: Thank you for sugesstion, I think I will try to use superglue

Cory: Thank you for the PDF, very informative

Yus, if there is some mechanical reason behind the shift, you should see the issue getting worse by increasing the magnification.

Besides, there can be some issue with the scanning signal as well. If possible, check the scanning ramp signal with an oscilloscope and note any deviations from a standard ramp signal.

Hello

Here are my ten items which could be responsible for image shift

1- Check the tape you use to place the  sample on

2-Check the tape you use on the stub

3-Check the dryness of the sample

4-Check the vibration table the SEM is sitting on

5-check the microscope for hydrocarbon contamination needs a qualified person

6 –Check the type of the sample soft tissue samples versus hard tissue sample as soft tissue samples are more apt to vibrate more

7-check the line generating card needs  a qualified person

8-check scanning board needs  a qualified person

9-check if the sample is charging

10- see  if another SEM can be used and are you getting the same results.

Hope I  have  helped

Professor K.Galil

Image shift (at non-tilted samples) are usually related to electric charging. The observed charging can be caused by a) the sample, or b) the SEM itself. A simple test is to check the imaging without any sample, e.g. using a sample holder or simply imaging the stage. If you observe already there the shift either your ground cable is not working anymore correctly, or you have some charging part in your microscope. This might be an attached device like detectors, cables, etc. or some contamination at apertures or within the electron column.   

If the SEM sample chamber is heavily contaminated by hydrocarbon contamination, hydrocarbon may build on detector, liner tube, bottom electrodes, or aperture. Because hydrocarbon is not a good conductor, it may cause charging inside the electron optics column. In this cause, the column has to be cleaned completely. To avoid such costly fix, it's recommended to keep SEM sample chamber free of hydrocarbon contamination. EM-KLEEN remote plasma cleaner can effective remove the hydrocarbon contamination inside the SEM/FIB sample chamber. Run a 10 minute plasma cleaning session whenever you observe obvious dark scan mark. It can effectively reduce beam position drift and focus drift in SEM images.

http://www.piescientific.com/Product_Remote_Plasma_Cleaner