Miki Goto

Effects of Fluorocarbon Films on CF Radical in CF4/H2 Plasma

The behavior of CF radicals in CF4/H2 plasma was studied as a function of the fluorocarbon film thickness grown on the inner wall in dc-pulsed CF4/H2 hollow cathode discharge plasma. Laser-induced fluorescence was used to examine the temporal behavior and radial distribution of the CF radical density. The thickness of the fluorocarbon films grown on the inner wall of the cylindrical hollow cathode was measured to investigate the influence of fluorocarbon film formation on the CF radical density in the plasma. For CF4/98%H2 discharge plasma, the radial distribution of the CF radical density deviated slightly from the zeroth-order Bessel function. The radial distribution of CF radical density changed to a uniform profile in CF4/98%H2 discharge plasma after exposure of the tube wall to CF4/20%H2 discharge.

Measurements of Diffusion Coefficient of CF2 Radical in DC Pulsed CF4/O2 Discharge Plasma

Laser-induced fluorescence has been used to measure the CF 2 radical ground-state densities after extinction of DC pulsed CF 4 /O 2 discharge plasma. From the measurement, the CF 2 radical was shown to be removed mainly by a diffusion process. Its diffusion coefficients are found to be D=150 cm 2 .Torr.s -1 in O 2 and D=65 cm 2 .Torr.s -1 in CF 4 at room temperature

Highly Sensitive Laser Absorptiometric Method Using Triple-Prism Multireflection System

To obtain high sensitivity in absorptiometry using a standard cell with a 1 cm light path length, two new optical systems have been designed. The sensitive absorptiometric system using the twin or triple prism coupling method provides 10-18 times higher sensitivity than does the ordinary absorptiometer.

Plasma Parameters in Low-Pressure Ar-Hg Discharge Plasma Used for Liquid Crystal Display Back-Lighting.

The electron temperature and electron density in the tube axis of a low-pressure Ar–Hg discharge lamp with 4 mm bore diameter have been measured under various bath temperatures with a probe method. Results show that the relative changes in the bath temperature dependence of electron temperature and electron density are similar to those obtained in the 36 mm I.D. discharge tubes. However, the electron temperature values are twice as large. The electron densities measured by the four methods used here are in good agreement with one another, indicating the reliability of the results.

Measurement of Diffusion Coefficient of CF2 Radical in DC Pulsed CF4/H2 Discharge Plasma.

Laser-induced fluorescence has been used to measure the CF2 radical ground-state densities after extinction of DC pulsed CF4/H2 discharge plasma. From the measurement, the CF2 radical was shown to be removed mainly by a diffusion process. Its diffusion coefficients are found to be D=430 cm2Torrs-1 in H2 and D=65 cm2Torrs-1 in CF4 at room temperature.

Reactive ion etching of CVD diamond thin films in O2/CF4 plasma

Reactive ion etching of chemical vapor deposition (CVD) diamond thin films was investigated in O2 gas plasma mixed with CF4 and electrodes distance. The optical emission spectrum of plasma species in excited electronic states was measured in order to know the information of relationship between etching rate of diamond and the concentrations of key reactive species. The RF power (13.56 MHz) was fixed at a constant 100 W. The large etching rate was obtained by using O2/20% CF4 at electrodes distance of 1.5 cm, O2 flow rate of 20 sccm and total pressure of 20 Pa. Etched diamond surface was observed SEM micrographs. The diamond surface in O2/20% CF4 plasma was smoother as compared with one in pure O2 plasma. The emission intensity of O had a peak around O2/20% CF4. The results of etching rate and emission intensity agree well with each other.

Influence of wall heating on CF2 radical in CF4 hollow cathode discharge plasma

The behavior of CF2 radicals was studied as a function of the temperature of the wall of the cylindrical cathode in dc-pulsed CF4 hollow cathode discharge plasma. Laserinduced fluorescence was used to examine the temporal behavior and radial distribution of CF2 radical density. The CF2 radical density increased about six times in magnitude by changing the wall temperature between 22°C and 100°C. The surface loss probability for CF2 radicals was estimated from the radial distribution of the CF2 radical density in the active plasma. The results show that the increase of the CF2 radical density in the heated wall can be interpreted as a decrease in the surface loss probability of CF2 radicals.

Mercury ion density in low-pressure Ar-Hg discharge plasma used for liquid crystal display backlighting

The mercury ion density in the tube axis of a narrow low-pressure Ar-Hg discharge lamp was measured with a modified absorption method. The electron density was measured with a probe method. The positive column of a discharge system is studied under the following conditions: Ar pressure 400 Pa (3 Torr); tube radius 2 mm; cold-spot temperature 0-80° C and discharge current 20 mA. It is shown that mercury molecular ion density is determined by combining the modified absorption method with the probe method.