Specific Process Knowledge/Lithography/EBeamLithography/JEOLJobPreparation: Difference between revisions

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 ==Beam pitch and dose relationship==
-The SDF command '''SHOT A, n''' defines the shot pitch in steps of 0.25 nm as described above.
+A sample is exposed at a user selected beam current to provide a user defined exposure dose. The system will calculate the shot time (dwell time) of the beam to provide the requested dose. It is clear that high doses will require long dwell times whereas low doses will require short dwell times. There is however another important parameter to the dwell time calculation and that is the beam/shot pitch, i.e. how far beam shots are placed from each other. The beam scanner on the JEOL 9500 system is 100 MHz, thus the temporal resolution is 10 ns and it is not possible to have a beam shot (or dwell time) less than 10 ns. This, in combination with selected beam current and exposure dose will set a lower limit on the beam pitch.
+The relation might not be obvious at first and is illustrated below. The two identical features are filled with beam shots at two different pitches. the right version has a lower beam pitch (half of the other) and thus there are simply many more beam shots. Consequently, to provide the same area exposure dose the shot time for the right side feature will be much shorter. At half the pitch there will be four times the number of beam shots and thus the shot time will be 1/4 the shot time of the left feature.
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