Dynamic Delay Correction
NanoMaker provides with one more absolutely unique feature to measure
and apply active countermeasures of dynamic distortions of deflection
system. Till now only one way has been used to solve this problem that
is switching off the e-beam by a blanker. This actually means to de-energize
for some period of time. It dooms to downtime. Though the duration of
such stoppages is estimated in milliseconds total time is long enough.
NanoMaker is supplied with a feature to avoid de-energizing and solve
the problem "on-the-fly" by calculation of the trajectory to provide
placement of the e-beam in the required place and point of time.
This feature makes microscopes lacking blanking system for carrying
out lithography. In case the microscope is equipped with mechanical
stage with laser interferometer NanoMaker enables both to design large
scaled structures with shifts and adjust microscope field settings.
This test was made in Raith GmbH
company to demonstrate the advantages of dynamic delays correction.
Writing was done with 13 bit resolution and 18 us dwell time on JSM
6400 without e-beam blanking system.
|Fig. 1a. Working principle of dynamic
||Fig. 1b. Test pattern for recognition
Fig. 1a shows the working principle of dynamic compensation. The design
of test pattern that was used to demonstrate the results of dynamic delays
correction during exposure session shown on Fig. 1b.
|Fig. 2a. Pattern written without dynamic
||Fig. 2b. Pattern written using dynamic
Fig. 2a shows the image of test pattern made without dynamic compensation
technique. The broken part is due to long (200 micrometers) e-beam leap,
after which the transient process in deflectors and amplifiers keep taking
place for several milliseconds. Such distortions can be corrected by standard
way that is by inputting Settling Time=1-10 milliseconds and blanking.
It results in time delay when designing and processing speed dwindles.
NanoMaker allows to calculate the trajectory of the e-beam and move it
to the right place at the right time. The Fig. 2b shows the result of
writing with active countermeasures of dynamic distortions of deflection