V. Shogun et al., APPLICATION OF AN ACOUSTOOPTIC SPECTROMETER FOR PLASMA-ETCHING PROCESS QUALITY-CONTROL, Surface & coatings technology, 74-5(1-3), 1995, pp. 571-574
The solution is proposed to the problem of the relative concentration
dynamics control of chemically active particles in the low temperature
gas plasma as well as the investigation of their generation and annih
ilation by means of time-resolved actinometry. A special small-size ac
ousto-optic spectrometer has been constructed capable of spectral reso
lution of 0.1-0.3 nm in the visible range (430-850 nm) and the maximum
time resolution of 2.0 mu s. The software package developed allows: (
1) measuring of the chronograms of the relative concentrations of vari
ous active particles in parallel mode at eight spectral channels; (2)
generating impulse plasma modulation and measuring the microdynamics o
f the generation and annihilation of the active particles in the frame
-by-frame mode (1024 points) in four parallel spectral channels, inclu
ding the two corresponding background values. To shorten the measureme
nt time and to improve the measurement accuracy of the particle annihi
lation kinetic characteristics in the interval between two stationary
(long) pulses, it is proposed to form a series of probing (short) puls
es. Some preliminary results are presented of the monitoring of the fl
uorine radicals (703.7 nm) relative concentration in the SF6 gas r.f.
plasma, containing as an actinometer a small amount (up to 5%) or argo
n (750.4 nm) at different discharge powers. Using the measurement resu
lts of the fluorine radicals, relative concentration in the pulse-modu
lated noble gas plasma obtained at monosilicon etching, the constants
of the radical accumulation, as well as their life time values, are de
termined for the loaded and unloaded reaction chamber.