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Schottky Diode Fabrication

This procedure is used early in the semester as part of the IC-CAP Tutorial to:

Starting Material: Almost any lightly doped N-type silicon will do.
Optional: Degrease the wafer.
Etch the wafer for 15-20 seconds in the "hot oxide etch" under the acid hood. (It is called "hot" because it is more concentrated than a standard oxide etch.)
Thoroughly dry the wafer. The bakeout hotplate may be used for up to 30 seconds. This step is important to improve pumping speed, but the hotplate may actually cause excessive native oxide to grow.
Use the Evaporator Instructions to manually deposit about 1500 angstroms of aluminum onto the shiny side of the wafer through an evaporation mask.
- Use the manual pumpdown procedure.
- Use 2 aluminum wires.
Use the etching instructions to etch back the aluminum for 10-15 seconds in aluminum etch.
Anneal your wafer in the annealing furnace for 10 minutes at 475C. This will improve the quality of the Silicon-Aluminum interface by raising the temperature to near the eutectic point. Some intermixing will occur and any interface problems such as voids, oxides, vacuum pump oil residues, etc. will be reduced.
In the paper version of the manual, the annealing furnace instructions are at the end of appendix F.
That's it! You have made a nonlinear electronic device called a Schottky diode!

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