triethyl gallium (TEGa)
non metal precursor: N2/H2 remote plasma
temperature controlled vapour draw
dose control by fast pulse ALD valve
deposition temperature: 150° - 350° C
A long plasma exposure is necessary to achieve a low oxygen
content and therefore a high refractive index. Although the
process saturates with a 5 second plasma, longer times
are needed to drive off the impurities to reach the impurity
levels quoted herein.
uniformity: < ± 0.5 - 2 %
(depending on substrate size)
C < 3% , O < 3%
refractive index 2.27
Up to 1.75 A/ min, > 10 nm/ hr (for 100 mm wafer)
(faster for smaller substrates)
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
efficient plasma preclean/ conditioning of the
substrates, lead to cleaner films and lower
the deposition temperature.
In Oxford systems it is possible
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.
valve between remote ICP source
spectroscopic ellipsometry optional