Hh. Doh et al., EFFECTS OF BIAS FREQUENCY ON REACTIVE ION ETCHING LAG IN AN ELECTRON-CYCLOTRON-RESONANCE PLASMA-ETCHING SYSTEM, Journal of vacuum science & technology. A. Vacuum, surfaces, and films, 15(3), 1997, pp. 664-667
Citations number
13
Categorie Soggetti
Physics, Applied","Materials Science, Coatings & Films
We examined the etch characteristics of SiO2 contact holes which have
the sizes of 0.3-1.2 mu m in a C4F8 + H-2 electron cyclotron resonance
plasma etching system. We varied the chamber pressure (3-7.5 mTorr),
microwave power (300-800 W), gas mixing ratio, bias voltage (100-300 V
) and bias frequency (100 - 800 kHz) as the experimental parameters to
investigate the reactive ion etching (RIE) lag. The RIE lag improved,
as the bias voltage increased and this RIE lag improvement was though
t to be due to the increase of ion energy incident on the substrate. T
he RIE lag also improved as the chamber pressure decreased and this im
provement is due to the increase of ion current density as the chamber
pressure decreases. When we increased the bias frequency from 100 to
800 kHz maintaining the same bias voltage, the RIE lag improved consid
erably. We calculated energy distribution of ions striking the rf bias
ed substrate using Monte Carlo particle-in-cell method to understand t
his phenomenon. The ion energy distributions are bimodal when the bias
frequencies are below 1 MHz, but as the bias frequency increases from
100 kHz to 1 MHz, the low energy part decreases and the high energy p
art increases, and it is suggested that this change of ion energy dist
ribution is responsible for the RIE lag improvement with the bias freq
uency increase. (C) 1997 American Vacuum Society.