T. Ikushima et al., LARGE-DIAMETER MICROWAVE SF6 PLASMA PRODUCTION WITH RING-SHAPED PERMANENT-MAGNETS, Journal of physics. D, Applied physics, 28(9), 1995, pp. 1851-1855
A large diameter and uniform microwave plasma (about 30 cm in diameter
) over 10 cm from the source has been produced by scaling up a prelimi
narily proposed device with an annular slot antenna and satisfying the
ECR (electron cyclotron resonance) condition in a chamber with neodym
ium ring-shaped permanent magnets. The spatial structure of the plasma
density in both non-reactive Ar and reactive SF6 gases was obtained b
y a Langmuir probe. The tentative etching of silicon (Si) was performe
d in the SF6 microwave plasma. The spatial profile of the etch rate in
the radial direction was found to be similar to that of electron dens
ity in the SF6 plasma. The uniformity of etch rate was within 2.5% at
the position where electron density profile reached the best uniformit
y (similar or equal to 5%). The etching profile of the poly-Si pattern
in the microwave plasma using pure SF6 gas was also observed by a sca
nning electron microscope (SEM).