Abstract:

The Central Fabrication Laboratory (CFL) is a cutting-edge cleanroom facility located at the University of Hong Kong. Its primary mission is to provide advanced fabrication facilities and expertise to enhance teaching and research activities in micro/nano fabrication. As a leading research laboratory, CFL offers open access not only to University of Hong Kong members but also to local and international institutions, researchers, and companies, with collaborations from the private sector always encouraged. The technical sharing sessions offered by CFL are designed to keep participants updated on the latest micro/nano fabrication techniques and provide valuable networking opportunities with experts from around the world.

Thermal evaporation sources include components that evaporate the base material through the use of resistive element heating. Typically, the bulk material is placed into a source made of refractory metal, and as power is applied, the temperature rises to facilitate evaporation. Installation costs and equipment are relatively inexpensive compared to other deposition techniques, but precise temperature control can be difficult, and some evaporants' tendency to alloy with the source material makes this technique not as universal as others. Department of Mechanical Engineering The University of Hong Kong

Similar to other techniques, the chamber pressure is brought to as low a level as possible to prevent background gases from chemically reacting with the film or bulk evaporant. Under carefully controlled partial pressures of reactive gases, reactive thermal evaporation can create films of a different chemical composition than that of the bulk material. The basic configuration typically includes a boat, filament, or crucible source with accessory feedthroughs, cross-contamination shielding, shutters, and appropriately sized power supplies.

Electron beam evaporation sources include components that evaporate the base material through the use of a high-energy electron beam, generating very high deposition rates (up to 25,000 Å/min). The electron beam is focused onto the target material through the use of a magnetic field, and bombardment of the electrons generates enough heat to evaporate a wide range of materials with very high melting points. Under regular e-beam evaporation, the chamber pressure is brought to as low a level as possible to prevent background gases from chemically reacting with the film or bulk evaporant. Under carefully controlled partial pressures of reactive gases, reactive e-beam evaporation can create films of a different chemical composition than that of the bulk material. The basic configuration typically includes an electron beam source, hearth, and top cover, with accessory feedthroughs and appropriately sized power supplies. Evaporation can be done directly from the hearth or with a crucible liner depending on the intended evaporation material.

Because of the ability to control deposition rate, low contamination, excellent material utilization, and very high deposition rates, electron beam evaporation is a highly adaptable technique used in many thin film deposition applications.

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