Plasma Technology  

AAO, anodic aluminium oxide, is a well-ordered
anoporous template, which is prepared by use
of an electrochemical technique and a thin piece
of Al as the anode. AAO-templates are widely used
for nanomaterials and nanotechnology.
The aspect ratio of the holes can be up 1000!
(hole diameter from 50-100nm and thickness of
template 70 micrometer) The figure above
presents a typical AAO before and
after ALD deposition.
ALD-ZnO, SiO2 and SiN can go through
the holes and form nano-tubes.

70 nm wide tube
100 µm long

highly conformal ZnO growth
with optimised process conditions

Si Nanowires etched by the cryo process
in the PlasmaPro 100 ICP etcher
coated with 150 nm AZO (Al doped ZnO)
in the FLexAL ALD system
with kind permission
Max Planck Institut für die Physik des Lichts
in Erlangen

ZnO ALD (thermal only)

precursor: DEZ
di ethyl zinc
non metal precursor: H2O

temperature controlled vapour draw

dose control by fast pulse ALD valve

deposition temperature: 50° - 200° C

cycle time 4 sec
thickness per cycle 1.9 A
(saturated dose)

resistivity 5 x E-3 ohm cm

C impurity < 2 at % at 150° C

uniformity: ± 1% (100 mm)

repeatability: ± 1%

refractive index: 1.90 - 1.95

Zn:O 1:1

GRC vs deposition (table) temperature

Growth rate per cycle and refractive index
vs DEZ dose time at 150° C


ALD schematic
valve between remote ICP source
and chamber,
spectroscopic ellipsometry optional


AES analysis shows Zn:O 1:1 and C < 2 at %




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