Wspólnotowy Serwis Informacyjny Badan i Rozwoju - CORDIS

Plasma source geometry for high plasma density generation over the whole source area

Plasma source geometry for high plasma density generation over the whole source area (1011 on 700 x 700 mm2):

Generate inductively coupled plasma over large area required the careful design of a coil antenna to create uniform magnetic field.

Plasma density measurements with 3 different coil geometries (2 loops, 2 serpentine coils and 3 loops connected in parallel) have shown clearly better results with the 3-loop coil. The corresponding ion current density is higher at the reactor periphery since it covers the whole magnetic pole area. Furthermore, the lead connection of the 3 antennas have been arranged outside the reactor, to keep the possibility to tune the plasma uniformity in balancing the power by tuning inductance. Nevertheless, the plasma profile presents a maximum at the reactor centre due to ambipolar diffusion. To decrease this effect, the magnetic pole located at the centre location have been removed in order to decrease the magnetic field i.e. to smooth the plasma profile.

The results are the following:
- Plasma uniformity with CHF3 gas:
--Original configuration: over 70 x 70mm2=20 %;
-- Removing 6 magnetic poles: 10%.

Etching rate optimisation of SiO2:
Etching experiments have been performed with the plasma source configuration described above.

Etching experiments made with CF4 and CHF3 gases gave very good results in term of etching rate and etching uniformity.
- SiO2 etching rate 70-100 nm/min
- Uniformity over 600 x 600 mm2 :10%

These performances are in the specifications.

Reported by

EC Joint Research Center
Via E. Fermi 1
21020 Ispra (VA)
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