Plasma Technology  


The AES analysis shows near stochiometric AlN.
Further work will be done to reduce the
C content (here 6 %).




FlexAl

 



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

AlN ALD (radical assisted by remote plasma)

Why remote plasma ALD ?

A "remote plasma" makes sure,
the substrates are NOT in contact
with the plasma !

The remote plasma just cracks molecules,
so that very reactive species can be used
for the growth process.

Such reactive species often enable a very
efficient plasma preclean/ conditioning of the
substrates, lead to cleaner films and lower
the deposition temperature.

In Oxford systems it is possible to run
ALD processes using
- the thermal only method
- ozone assisted processes
- remote plasma assisted processes
together without any hardware change.
Multiple step processes using all technologies
can be chosen from the software.

 

deposition temperature: 100° - 400° C

cycle time < 4 sec (for 200 mm wafer)
(shorter for smaller substrates, ca 3 sec)

0.58 A/ cycle (saturated dose at 300° C)
18 A/ min, > 100 nm/ hr (for 200 mm wafer)
(faster for smaller substrates)

uniformity: < ± 0.5 - 2 %
(depending on substrate size)

refractive index
1.86 at 300° C
1.94 at 400° C

 

growth per cycle vs plasma time

thickness vs deposition loops


metal precursor: TMA (tri methyl aluminium)
non metal precursor:
N and H radicals by N2/H2

temperature controlled vapour draw

dose control by fast pulse ALD valve

 

This process is well known in the literature to be a non-ideal ALD process in that it does not properly self limit when using NH3 as a thermal or plasma precursor.

Remote plasma ALD using N2/H2
overcomes this problem and shows
good ALD bevaviour !

refractive index vs wavelength
at 300° C and 400° C
deposition temperature


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