Specific Process Knowledge/Thin film deposition/Deposition of Alumina

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Deposition of aluminium oxide

Aluminium oxide (Alumina, Al₂O₃) can be deposited by use of ALD (atomic layer deposition), by e-beam evaporation or by sputtering. During the sputter deposition oxygen is added to the chamber resulting in aluminium oxide on the sample.

Comparison of the methods for deposition of Alumium Oxide

	Sputter-System(Lesker)	Sputter-System Metal-Oxide(PC1)	ALD Picosun 200	10-pocket e-beam evaporator
Generel description	RF sputtering from Al₂O₃ target Reactive sputtering	RF sputtering from Al₂O₃ target Pulsed DC reactive sputtering Reactive HIPIMS (high-power impulse magnetron sputtering)	ALD (atomic layer deposition) of Al₂O₃	E-beam evaporation of Al₂O₃ pellets or of Al in an O₂ flow
Stoichiometry	Not tested	Not tested	Al₂O₃, very good	Not tested yet
Film Thickness	few nm - 200 nm	few nm - 200-300 nm	0nm - 100 nm	few nm - 200 nm (talk to staff if you wish to deposit more than 100 nm as it can cause flaking in the chamber)
Deposition rate	0.3 nm/min	About 1.7 nm/min, depends on sputtering parameters	0.088 - 0.097 nm/cycle (Using the "Al2O3" recipe, temperature dependent)	1-2 Å/s
Step coverage	unknown	unknown	Very good. Covers sample everywhere (but long purge time needed for very high aspect ratio structures)	We expect no step coverage unless using tilt holder, in which case the step coverage can be very good and can be tuned.
Process Temperature	room temperature	Up to 600 °C	150 °C - 350 °C	Up to 250 °C
More info on Al₂O₃		See deposition conditions	Al₂O₃ deposition using ALD
Substrate size	chips 1x 100 mm wafer 1x 150 mm wafer	chips 10x 100 mm wafer 10x 150 mm wafer	1-5 100 mm wafers 1-5 150 mm wafers Several smaller samples	chips 1-3 x 100 mm wafers 1-3 x 150 mm wafers 1-3 x 200 mm wafers
Allowed materials	almost any that does not degas	almost any that does not degas. Note special carrier for III-V materials. See cross-contamination sheet.	Silicon Silicon oxide, silicon nitride Quartz/fused silica Al, Al₂O₃ Ti, TiO₂ Other metals (use dedicated carrier wafer) III-V materials (use dedicated carrier wafer) Polymers (depending on the melting point/deposition temperature, use carrier wafer)	almost any that does not degas. See cross-contamination sheet