plasma gas: N2/ H2
temperature controlled vapour draw
dose control by fast pulse ALD valve
deposition temperature: 100° - 500° C
cycle time < 12 sec for 200 mm wafer
(shorter for smaller substrates, ca 9 sec)
0.33 A/ cycle (saturated dose)
1.65 A/ min, 10 nm/ hr (for 200 mm wafer)
(faster for smaller substrates)
uniformity: ± 0.5 %
resistivity < 175 µ ohm cm
(uniformity +/- 2 %)
even at 350° C
(vs 550° C for purely thermal ALD)
Cl content < 1 %
valve between remote ICP source
spectroscopic ellipsometry optional
50 nm TiN grown on a 100 µm
deep trench etch with
aspect ratio of 300:1
bottom sidewall with 50 nm TiN
(roughness caused by the Bosch etch process)
EDS of TiN on the bottom Si trenches:
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.
low resistivity at low temperatures
from remote plasma reduction of TiCl4
compared to thermal ALD
substrate plasma preclean
plasma cleaning of the chamber
(SF6, typ 1 hour cleaning per month
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
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.
Saturation of TiCl4 showing
self limiting growth (200 mm wafer)
Growth per cycle (GPC)
vs plasma time
Cl content and resistivity
vs plasma time = radical exposure time
Longer radical exposure times help
to get higher quality films !