QUOTE (20nmon+Jun 18 2010, 04:59 AM)
I have been wondering if I specify an electron beam dose of 100 uC/cm^2, what is the actual secondary electron dose?
Wouldn't this vary for each different trial? Building the dose model seems futile.
For high energy beams, the primary electrons almost certainly go through the resist to the substrate. So it's only the secondary electrons defining the feature size.
Increasing the dose, normally you wouldn't expect the feature size to change, if you have fixed beam width, or assume fixed secondary electron range.
But since electron path distance is stochastic, increasing dose increases the likelihood of large electron range, or increasing the opportunity of random events of larger distance impact.
11th July 2010 - 02:33 AM
In NOR flash memory programming, the secondary electron tail distribution from hot holes is well known. The secondary electrons are desired to move in sufficient numbers well over ~10 nm at least to charge the floating gate. It might be a lithography issue but it is definitely a feature in key charge injection devices.
20th July 2010 - 02:46 PM
QUOTE (apd+Jun 18 2010, 02:18 PM)
It was recently pointed out to me that electron ionization is itself a statistically noisy process. The most common manifestation is the avalanche photodiode. I think you might be able to work with a mean number of electrons expected, but you cannot pin down the actual number, which is the number that holds real meaning (which is why APD noise is meaningful).
There have been reports of EUV dose calibration errors at Berkeley's Advanced Light Source. Almost a factor of two. I think it is related to sometimes you have two secondary electrons instead of one, for example.
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