Specific Process Knowledge/Thin film deposition/Deposition of Titanium Oxide

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Deposition of Titanium Oxide

Titanium oxide can be deposited at Nanolab by sputtering, e-beam deposition, or ALD (atomic layer deposition). In sputtering and e-beam deposition of titanium oxide, the target is Ti and oxygen is added to the chamber during the process resulting in Titanium oxide on the sample. Therefore some process development may be necessary to achieve the correct stoichiometry. The oxygen flow in e-beam evaporation is lower than in sputtering, so it may not be possible to obtain fully oxidized TiO₂, though we have not yet verified this.

• TiO2 deposition using ALD
• TiO2 deposition using Sputter-System Metal-Oxide(PC1)
• TiO2 deposition in Sputter System (Lesker)

We also used to have the option to sputter-deposit TiO2 with the IBE/IBSD Ionfab300.

Comparison of the methods for deposition of Titanium Oxide

	E-beam evaporator (10-pockets)	Sputter-system Metal-Oxide(PC1)	Sputter-System(Lesker)	ALD Picosun 200
Generel description	Evaporation of Ti or TiO2 pellets in the presence of a O2 flow. Can heat up to 250 °C	Reactive DC sputtering of Ti target Reactive or non-reactive RF sputtering of TiO2 target Reactive pulsed DC sputtering Reactive HIPIMS (high-power impulse magnetron sputtering) Can heat up to 6000 °C	Reactive DC sputtering of Ti target in Ar/O2 (10 % O2) plasma RF sputtering of TiO2 target	ALD (atomic layer deposition) of TiO2 Can heat up to 350 °C
Stoichiometry and form	Can probably be varied, expect somewhat O-poor composition	Can probably be varied	Can probably be varied	Temperature dependent - Anatase or amorphous TiO2
Film Thickness	few nm - 100 nm	~10 nm - ~0.5 µm	~10 nm - ~0.5 µm (>2h)	few nm - 100 nm
Deposition rate	1-10 Å/s Ti deposition rate (oxidized layer growth should be faster; actual growth rate will need testing)	not yet known, probably faster than Sputter-System(Lesker)	3-5 nm/min (RF sputtering) 0.3 - 0.5 nm/min	0.06 nm/min - 0.40 nm/min (very recipe and temperature dependent)
Step coverage	expect no step coverage unless the tilted sample holder is used, in which case step coverage should be very good and may be tuned with the tilt angle.	Not Known	Not Known	Very good. Covers sample everywhere (but long purge time needed for very high aspect ratio structures)
Process Temperature	RT to 250 °C	RT to 600 °C	RT	120 °C - 150 °C: Amorphous TiO2 300 °C - 350 °C: Anatase TiO2
More info on TiO2	Expect lower density than bulk material of same stoichiometry.	TiO2 deposition using Sputter-System Metal-Oxide(PC1)		ALD1: TiO2 deposition using ALD1 ALD2: TiO2 deposition using ALD2
Substrate size	Up to 4x6" wafers Up to 3x8" wafers (ask for holder) smaller pieces	many small samples Up to 10x 100 mm or 150 mm wafers	several small samples several 50 mm wafers (Ø150mm carrier) 1x 100 mm wafers 1x 150 mm wafers	ALD1: 1-5 100 mm wafers 1-5 150 mm wafers 1 200 mm wafer Several smaller samples ALD2: 1 100 mm wafer 1 150 mm wafer 1 200 mm wafer Several smaller samples
Allowed materials	Almost any material that does not outgas at your intended substrate temperature and is not toxic See the cross-contamination sheet	Almost any material that does not outgas at your intended substrate temperature Pb and other toxic materials only after special agreement	Almost any that do not outgas and are not very toxic Dedicated carrier for III-V materials See cross-contamination sheet	Silicon Silicon oxide, silicon nitride Quartz/fused silica Metals - Use a dedicated carrier wafer III-V materials - Use dedicated carrier wafer Polymers - Depending on the melting point/deposition temperature, use dedicated carrier wafer. Ask for permission