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All contents by Nanolab staff.
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.
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
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E-beam evaporator (10-pockets)
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Sputter-system Metal-Oxide(PC1)
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Sputter-System(Lesker)
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ALD Picosun 200
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Generel description
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- Evaporation of Ti or TiO2 pellets in the presence of a O2 flow.
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- 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)
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- Reactive DC sputtering of Ti target in Ar/O2 (10 % O2) plasma
- RF sputtering of TiO2 target
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- ALD (atomic layer deposition) of TiO2
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Stoichiometry and form
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- Can probably be varied, expect somewhat O-poor composition
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- Temperature dependent - Anatase or amorphous TiO2
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Film Thickness
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Deposition rate
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- 1-10 Å/s Ti deposition rate (oxidized layer growth should be faster; actual growth rate will need testing)
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- not yet known, probably faster than Sputter-System(Lesker)
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- 3-5 nm/min (RF sputtering)
- 0.3 - 0.5 nm/min
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- 0.06 nm/min - 0.40 nm/min (very recipe and temperature dependent)
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Step coverage
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- 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.
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- Very good. Covers sample everywhere (but long purge time needed for very high aspect ratio structures)
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Process Temperature
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- 120 °C - 150 °C: Amorphous TiO2
- 300 °C - 350 °C: Anatase TiO2
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More info on TiO2
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- Expect lower density than bulk material of same stoichiometry.
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ALD1:
ALD2:
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Substrate size
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- Up to 4x6" wafers
- Up to 3x8" wafers (ask for holder)
- smaller pieces
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- many small samples
- Up to 10x 100 mm or 150 mm wafers
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- several small samples
- several 50 mm wafers (Ø150mm carrier)
- 1x 100 mm wafers
- 1x 150 mm wafers
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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
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Allowed materials
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- Almost any material that does not outgas at your intended substrate temperature and is not toxic
- See the cross-contamination sheet
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- Almost any material that does not outgas at your intended substrate temperature
- Pb and other toxic materials only after special agreement
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- 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
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