Specific Process Knowledge/Thin film deposition/Deposition of Aluminium Nitride

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Deposition of Aluminium Nitride

AlN films can be deposited by sputtering or by atomic layer deposition (ALD).

In the sputter systems AlN can be either deposited by direct sputtering of an AlN target or reactive sputtering with an Al target in mixtures of argon and nitrogen.

Comparison of the methods for deposition of AlN

Sputter-System (Lesker) Sputter-System Metal-Nitride(PC3) ALD2
Generel description
  • 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
Stoichiometry
  • 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 here). It should be possible to tune the Al:N ratio somewhat.
  • AlN
Film Thickness
  • few nm - 200 nm
  • few nm - ~ 1 μm
  • 0nm - 50 nm
Deposition rate
  • 0.055 nm/s (Power: 300W, pressure:1 mTorr, temp.: 400C, N2 ratio: 50%)
  • 0.0625 nm/cycle on a flat sample
  • 0.0558 nm/cycle on a high aspect ratio structures
Step coverage
  • Good
  • Not known, most likely medium-good
  • Very good
Process Temperature
  • Up to 400 °C
  • Up to 600 °C
  • 350 °C
Substrate size
  • chips
  • 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
Allowed materials
  • Silicon
  • Silicon oxide, silicon nitride
  • Quartz/fused silica
  • Photoresist
  • PMMA
  • Mylar
  • SU-8
  • Any metals
  • 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)

Further process information can be found here: