Specific Process Knowledge/Thin film deposition/Deposition of Aluminium Nitride: Difference between revisions

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+''All text by DTU Nanolab staff''
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-== Deposition of Aluminium Nitride ==
+=Aluminium Nitride (AlN)=
+Aluminum nitride (AlN) is a wide‑bandgap (~6.2 eV) ceramic that pairs very high thermal conductivity (> 200 W m<sup>-1</sup>K<sup>-1</sup> ), strong piezoelectric and acoustic properties, and a high dielectric breakdown field in a chemically inert, CMOS‑compatible matrix.
+It is deposited by reactive magnetron sputtering for dense, c-axis-oriented films widely used in RF devices, and by atomic layer deposition (ALD) when conformal, thickness-precise coatings are required on high-aspect-ratio or temperature-sensitive structures.
+In semiconductor technology, AlN acts as a nucleation or buffer layer for GaN power/high‑frequency devices, a robust passivation and diffusion barrier, and—when alloyed with Sc—to form ferroelectric AlScN for next‑generation non‑volatile FeFETs and piezoelectric MEMS actuators.
+Optically, its transparency from deep-UV to the IR and modest refractive index (~2.1) enable low-loss waveguides, UV LEDs/lasers, and protective or anti-reflective coatings that withstand high optical power and harsh environments.
+AlN’s strong piezoelectricity and high acoustic velocity underpin surface‑ and bulk‑acoustic‑wave filters, film bulk‑acoustic‑resonators, energy harvesters, and high‑Q MEMS resonators used in 5G RF front‑ends and timing devices.
+Beyond electronics and photonics, AlN substrates and thin films offer excellent thermal management for power modules, high-temperature, biocompatible passivation layers for sensors and implants, and mechanically robust coatings for corrosion and wear resistance, thereby cementing its role as a versatile thin-film material across semiconductor, optical, and engineering applications.
+= Deposition of Aluminium Nitride =
+AlN films can be deposited by reactive sputtering or by atomic layer deposition (ALD).
+In sputter systems, AlN can be deposited either by direct sputtering of an AlN target or by reactive sputtering with an Al target in a mixture of argon and nitrogen.
+==Atomic Layer Deposition of Aluminium Nitride (AlN)==
-AlN can be deposited by using sputtering method with AlN target or reactive sputtering method with Al target in mixtures of argon and nitrogen. AlN film can be deposited by using the [[Specific Process Knowledge/Thin film deposition/Multisource PVD|Cryofox PVD co-sputter/evaporation]]  or  the [[Specific Process Knowledge/Thin film deposition/Lesker|Lesker Sputter System]].
+Aluminium Nitride (AlN) can be deposited using the plasma-enhanced atomic layer deposition method from TMA and NH3 precursors. The process is well known, and the following link describes all the details:
-*[[/AlN in PVD co-sputter|Al<sub>x</sub>N<sub>y</sub> in PVD co-sputter/evaporation]] <br/>
+*[[Specific Process Knowledge/Thin film deposition/ALD2 (PEALD)/AlN deposition using ALD2|AlN deposition using ALD2]]
+==Reactive p-DC Sputtering of Aluminium Nitride (AlN)==
-<br clear="all" />
+[[Specific_Process_Knowledge/Thin_film_deposition/Cluster-based_multi-chamber_high_vacuum_sputtering_deposition_system|Cluster Lesker]] is the best option for deposition of AlN, especially the Sputter-System Metal-Nitride(PC3) chamber, which has no history of oxygen.  The process requires elevated temperatures and uses an Al substrate as a source. The films are highly textured. To improve quality, it is also possible to [[Specific Process Knowledge/Thin film deposition/Deposition of Scandium Nitride/ScN Reactive Sputtering in Cluster Lesker PC3|dope the AlN with scandium]]. At DTU Nanolab, there is an option to perform co-sputtering of both [[Specific Process Knowledge/Thin film deposition/Deposition of Scandium/Sc Sputtering in Cluster Lesker PC3|Sc]] and [[Specific Process Knowledge/Thin film deposition/Deposition of Aluminium/Al Sputtering in Cluster Lesker PC3|Al]] at different powers to get ScAlN thin films.
-==Only one method at the moment==
+==Comparison of the methods for deposition of AlN==
 {|border="1" cellspacing="1" cellpadding="3" style="text-align:left;"
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 !
-![[Specific Process Knowledge/Thin film deposition/Multisource PVD|Cryofox PVD co-sputter/evaporation]]
+![[Specific Process Knowledge/Thin film deposition/Lesker|Sputter-System (Lesker)]]
+![[Specific_Process_Knowledge/Thin_film_deposition/Cluster-based_multi-chamber_high_vacuum_sputtering_deposition_system|Sputter-System Metal-Nitride(PC3)]]
+![[Specific Process Knowledge/Thin film deposition/ALD2 (PEALD)|ALD2]]
 |-
 |-style="background:WhiteSmoke; color:black"
 !Generel description
 |
-*Reactive Sputtering (Al target) or AlN target sputtering
+*Reactive Sputtering (2" Al target)
+|
+*Pulsed reactive DC sputtering (PDC, 4" Al target)
+*Reactive HIPIMS (high-power impulse magnetron sputtering)
+|
+*Plasma Enhanced Atomic Layer Deposition
 |-
 |-style="background:LightGrey; color:black"
 !Stoichiometry
 |
-*Depend on the targets power
+*Oxygen contamination issue (in 2016 a user got ~ 30 % O in the AlN, measured by XPS in the bulk of the layer).
+|
+*Al:N:O ~ 53 : 46 : 1.5 in the bulk (see acceptance test results [[Specific_Process_Knowledge/Thin_film_deposition/Cluster-based_multi-chamber_high_vacuum_sputtering_deposition_system#Process information|here]]). It should be possible to tune the Al:N ratio somewhat.
+|
+*AlN
 |-
 |-style="background:WhiteSmoke; color:black"
 !Film Thickness
 |
-* 0nm - 200nm
+* few nm - 200 nm
+|
+* few nm - ~ 1 μm
+|
+* 0nm - 50 nm
 |-
 |-style="background:LightGrey; color:black"
 !Deposition rate
 |
-* Not tested
+* 0.055 nm/s (Power: 300W, pressure:1 mTorr, temp.: 400C, N2 ratio: 50%)
+|
+* at least 0.5 nm/s ([[Specific_Process_Knowledge/Thin_film_deposition/Cluster-based_multi-chamber_high_vacuum_sputtering_deposition_system#Standard recipe performance|see conditions]])
+|
+* 0.0625 nm/cycle on a flat sample
+* 0.0558 nm/cycle on a high aspect ratio structures
 |-
 |-style="background:WhiteSmoke; color:black"
 !Step coverage
+|
+*Good
+|
+*Not known, most likely medium-good
 |
 *Very good
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 !Process Temperature
 |
-* Up to 400<sup>o</sup>C
+* Up to 400 °C
+|
+* Up to 600 °C
+|
+* 350 °C
 |-
 |-style="background:LightGrey; color:black"
 !Substrate size
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-* 100 mm wafers (Up to 12 wafers at a time)
+* chips
-* 150 mm wafers (Up to 4 wafers at a time)
+* 1x 100 mm wafer
+* 1x 150 mm wafer
+|
+* chips
+* 10 x 100 mm wafer or
+* 10 x 150 mm wafer
+|
+*Several small samples
+*1 50 mm wafers
+*1 100 mm wafers
+*1 150 mm wafer
 |-
 |-style="background:WhiteSmoke; color:black"
-!'''Allowed materials'''
+!Allowed materials
 |
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 *SU-8
 *Any metals
+|
+*Similar to the Sputter-System (Lesker), see [http://labmanager.dtu.dk/function.php?module=XcMachineaction&view=edit&MachID=442 cross-contamination sheet]
+|
+*Silicon
+*Silicon oxide, silicon nitride
+*Quartz/fused silica
+*Al, Al<sub>2</sub>O<sub>3</sub>
+*Ti, TiO<sub>2</sub>
+*Other metals (use dedicated carrier wafer)
+*III-V materials (use dedicated carrier wafer)
+*Polymers (depending on the melting point/deposition temperature, use carrier wafer)
 |-
 |}
+*For further information on AlN deposition using the sputter systems, please contact the Thin Film Group ([mailto:thinfilm@nanolab.dtu.dk thinfilm@nanolab.dtu.dk]). The Sputter-System Metal-Nitride(PC3) was acquired partly to make it possible to deposit high-quality of AlN films.