SEM charging of metallic features on insulating samples

Sep 14, 2004 5 Replies
F

I have to work with SEM data coming from metallic lines on insulating samples all the time. What guarantees are there that charging is not throwing an element of random distortions into my data?



I know that at a suitably low voltage, this can be controlled to some extent since secondary electron emission can balance the incident electron flux. But this control must be material dependent and I doubt complete cancellation is always possible.



Are there ways to avoid this type of uncertainty?



Thanks, Fred


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J

Metallize with Au-Pd. If not yet completely satisfactory, metallize at the onset with carbon, then with Au-Pd. Put a copper electron microscope grid on each sample you ought to investigate, as a test object.

J.J.

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F

It turns out I cannot afford to coat these discharging layers because that is a final, pseudo-destructive step. This issue burned us once again, we have pictures of the image drifting in the field window.

Are there any systems which employ a gaseous ambient?

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J

SEM supply shops (SPI,etc...) sell antistatic sprays. Good for observations, but prolonged exposure to the electron beam burns the coating on the spot, which is difficult to remove. Regular sprays sold for electric uses are not effective.

J.J.

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F

Thanks, that is an intriguing suggestion.

How do Environmental SEMs perform?

Fred

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W

Is it possible to bridge from the metallic portion to a grounded area simply with silver paint? This could later be removed with a volatile solvent like acetone or lacquer thinner. Make sure the necessary thinner won't 'eat' the insulator.

Fred Chen wrote:

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