Specific Process Knowledge/Lithography/EBeamLithographyManual: Difference between revisions

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 The beam diameter changes as a function of aperture size and beam current. Simulated beam diameter in the current range 0.01-1000 nA for the available aperture sizes is plotted in the graph below.
+= Mounting of chips or wafers into cassette =
+NOTE that wafers are mounted with major flat upwards and your pattern should thus be designed in the same way.
+Wafer cassettes must be handled with great care and with an extra pair of clean gloves (to be found inside the e-beam room). Prevent any form of impact of the cassette and never touch the delicate parts of the cassette, i.e. the reference plane, reference marks or grounding pins. Take care that the cassette is not scratched against the metal table, always keep cleanroom side-sealed lintfree tissues between cassette and table.
+General rules for handling cassettes and mounting wafers and chips into cassettes:
+*Always wear face-mask and a new pair of gloves
+*Never touch the reference planes, i.e. the six polished areas on the front side of the cassette
+*Never lift the cassette in the hook
+*Always check the wafer for loose parts or flakes before loading. In case of loose parts or flakes, stop mounting, discard or rework the sample and rethink your process.
+*Always check the cassette for loose parts, dust and particles.
+*For chips: Make sure the chip size is at least 2 mm larger than the slot opening. Be careful when mounting the plate; it will get stuck easily if mounted askew. Always check that the 12 large screws are tight.
+*For wafers: When mounting a wafer, hold the spring (wafer securing pin) back when putting the wafer and the plate into the cassette, especially on the 2" cassette (the spring can lift the wafer). Tighten the leaf spring first, then release the spring and tighten the rotation lock lever.
+*Inspect the front side of the cassette carefully after mounting the chip/wafer; a small gap between substrate and cassette will lead to a failure in HEIMAP and no exposure is thus possible.
+Seen from the front-side of the cassette with the hook to the right, the workpiece windows (wafer positions) are named A, B, C etc in reading-direction from top left to bottom right.