Plasma Technology  

The AES analysis shows near stochiometric SiO2.

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

Conformal SiO2 growth by
remote plasma ALD
over a 30 : 1 aspect ratio trench

SiO2 ALD (radical assisted by remote plasma)

precursor: BTBAS
(3DMAS and 2DEAS have also been used)
O radicals and O2

bubbled at 35° C

dose control by fast pulse ALD valve

Good self limiting process

deposition temperature: 100° - 400° C

cycle time 9 sec (for 200 mm wafer)
(shorter for smaller substrates)

1.4 A/ cycle (saturated dose at 290° C)
9 A/ min, > 56 nm/ hr (for 200 mm wafer)
(faster for smaller substrates)

BHF wet etch rate < 100 nm/ min (300°C)
(< 150 nm/ min with 3DMAS)

uniformity: < ± 1 - 3 %
(depending on substrate size)

repeatability < ± 1 %

C < 4 % (at 400 °C)

refractive index 1.42 - 1.44

The Si:O ratio is 1:2.

Growth rate per cylce (GRC) vs
the metal precursor dose time

Growth rate per cycle vs plasma on
= radical exposure time





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.

substrate plasma preclean
plasma cleaning of the chamber
(SF6, typ 1 hour cleaning per month
of operation)


Growth Rate per Cycle (GRC)
and refractive index
vs deposition temperature

link to homepage email to OPT