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--- ebpg_raith-100 [2025/01/16 10:26] – wigbout
+++ ebpg_raith-100 [2025/07/29 10:30] (current) – wigbout
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+====== Raith 100 E-beam Lithography (EBL) ======
+===== Introduction =====
+The Raith 100 is a direct-write machine used for maskless lithography.
+A 30 keV electron beam is emitted from a field-emitter, and is focused through electromagnetic lenses.
+Using a deflection system the beam can be moved in the xy-plane.
+Lithography is crucial for the [[https://en.wikipedia.org/wiki/Planar_process|planar process]] (i.e. fabrication of devices), since it is one of the few techniques((along with, e.g. FIB and (F)EBID)) that allows //local// changes, whereas deposition and etching typically is a //global// step.
+If you would like to use this system, contact [[wigbout@physics.leidenuniv.nl|Luc Wigbout]].
+**The Raith 100 EBL system is located in the Cleanroom. Before you can use this system, you should have had a [[Cleanroom Safety Training]].**
+----
 ===== Preparing and loading substrate =====
   - Spincoat your resist of choice, see [[resist_and_e-beam_recipes|resist recipes]]
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 ===== Extra reading =====
 {{ :fundamentals_of_electron_beam_exposure_and_development.pdf|}}
+===== New manual (WIP) =====
+==== The electron beam and writing fields ====
+The Raith-100 e-beam lithography machine can be used to pattern nanoscale structures using an electron beam. The system is, in essence, an scanning electron microscope (SEM) with additional features such as a pattern generator that can write the desired patterns.
+The e-beam is generated by thermionic emission from a hot cathode emitter at an energy of 30 keV, after which it is formed by the Wehnelt cylinder and several lenses (a.o. the stigmator and objective lens). Within the lens-column, there is also a deflector housed, which can change the incident angle of the electron beams. The amount of power necessary the deflect the 30 keV e-beam, increases with the beam angle. Thus, deflections at larger angles need bigger amplification. In the Raith-100, the large amplifiers tend to be noisy, so when writing, we will keep to the smaller amplification, so that the maximum angle corresponds to a field of view of 400x400 um.
+The system can still be used as a SEM, were the electron beam is scanned across an area. The scanning movement is ‘locked-in’ with a detector such that an image can be created. The area that is imaged, is the field of view (FOV) at that specific magnification, e.g., at 575x mag., the FOV is 400x400 um and at 2300x mag., the FOV is 100x100 um.
+When writing, we typically use 100x100 um as the area of our writing fields (WF). Thus, the WF is the area onto which can be written by purely changing the deflection of the beam.
+Since most patterns tend to be a bit larger than 100x100 um, we have to come up with creative solutions as not to write a noisy pattern. One way of overcoming this issue, is by stitching several WF's in two dimensions. This can be done by moving the sample with high accuracy.
+==== WF alignment ====
+The sample is put onto a sample holder which can be mounted inside the Raith-100 onto a stage with sapphire ball spacers to ensure that it is held in place with extreme accuracy. Furthermore, the sample stage can be moved in X and Y directions. The movement is measured with a laser-interferometer.
+:!: __Be aware that when you mount the sample, the stage should be in the exchange position. Otherwise the mirrors of the interferometer could be exposed to the outer environment (and potentially get dusty).__
+By moving the stage 100 um along the X or Y axis, one could switch to another part on the sample. In order to make sure that all the WF’s are aligned--connect properly--a WF-alignment procedure has to be done. This procedure makes sure that all the writing fields are correctly stitched to each other.
+WF alignment with images is done using an automated function, which does the following. After you searched for a particle or clear feature with a size of about 5 um, the procedure takes an image.