Clustering phenomena in low-pressure reactive plasmas. Basis and
applications*
Y. Watanabe, M. Shiratani, and K. Koga
Faculty of Information Science and Electrical Engineering,
Kyushu University, Fukuoka 812-8581, Japan
Abstract: Clustering phenomena of particles below a few nm in
size in low-pressure reactive plasmas have been studied in capacitively
coupled high-frequency SiH4 discharges. Clusters nucleate around a size
of 0.5 nm, Si4Hx and subsequently grow due to influxes of SinHx (1 <
n < 4) and other molecular species. Because of long gas-residence
time and small surface loss-probability of clusters, even neutral ones
accumulate to nucleate in the reactor. Appearance of negatively charged
clusters is considered to become noticeable at around Si4Hx. The growth
of clusters is suppressed by using thermophoretic force, gas flow, periodical
discharge modulation, and hydrogen dilution. The reactor has been newly
developed to suppress the growth of clusters both by thermophoretic
force and by gas flow and evacuation without stagnation. Using the reactor,
a-Si:H films of extremely high quality have been successfully deposited.
* Lecture presented at the 15th International Symposium
on Plasma Chemistry, Orléans, France, 9-13 July 2001. Other presentations
are presented in this issue, pp. 317–492.
** Corresponding author.
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