Specific Process Knowledge/Lithography/EBeamLithography/JEOL 9500 User Guide: Difference between revisions

After cassette transfer the system has to be calibrated with the chosen beam current condition profile. This is done in a mostly automated sequence with only minute input from the user. The sequence is explained in detail in the following but in overview it is

The SDF specifies which system condition file to use for the exposure, this determines the beam current. Condition files are named according to beam current and beam aperture, for instance '''6nA_ap5''' which will expose at 6 nA using aperture 5. Restoring a condition file for use is done from the '''Calibration''' window, if it is not open it can be opened from the '''EBX Menu'''.

*Browse and select the condition file to use and click '''OK'''  

With the correct condition file restored the next step is to measure beam current and verify that it is close to the expected value.  

The stage moves to the faraday cup to measure beam current. This takes 15 seconds and the '''Calibration''' window will display the measured beam current. Note this down for the Labmanager usage log. If the value is more than 5% off the expected beam current call the e-beam responsible for assistance.

During calibration the system will measure and display the beam position at 49 locations of the writing field. The position error (in nm) can be read of the matrices during execution, an example is shown below. At the end of the process the '''Calibration''' window will display '''Finished BATCH CALIB'''.

In this example the two drift measurements are made a bit more than 1 minute apart (look at timestamps). The x-axis drift has changed from 65.4 nm to 64.2 nm, i.e. a change of 1.2 nm in about 1 minute. The y-axis drift has changed from 85.3 nm to 86.8 nm, a shift of 1.5 nm in about 1 minute. Thus the drift is about 1-1.5 nm/min in this particular example. This is a typical value. If you experience drift of 5-10 nm/min, give the system 10 min to thermally equilibrate and try again. If drift is above 10 nm/min please call the e-beam personnel for assistance.

Parameter window of the '''HEIMAP''' subprogram. Image: Thomas Pedersen.

The example above will create a 3x3 matrix of height data with a pitch of 1 mm in x and y. After execution the system will display a matrix with height measurement data in µm. Verify that there are no outliers and that variation is less than 100 µm from top to bottom.

The system will now carry out initial and cyclic calibration as defined by the path in the JDF file and then exposure will start. The pattern writing can be observed in the SSP window (top left) once it starts. Progress can be monitored in the '''Expose''' window which will give a completion percentage and completion time for the current sequence. Once exposure is completed the system will confirm this with the '''Pattern writing completed''' window.