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The kinetics of hydrogen peroxidecatalyzed ozonation was studied in aqueous solutions of various lower alcohols containing ethanol as a reference. The relative rates of degradation of alcohols obtained support the initiation of the reaction by hydroxyl radicals formed in the reaction between ozone and hydrogen peroxide.

A new-type electron-cyclotron-resonance (ECR) plasma source has been developed for materials processing. The reactor employed magnetic multicusp fields and microwaves radially injected through an annular slit; this configuration yielded stable, uniform discharges without contamination of the microwave entrance window by sputtered particles. Electrostatic probe and optical emission measurements were made to obtain the plasma properties in Ar. These measurements showed that high-density, uniform plasmas were produced by optimizing the width of the annular slit. Moreover, the electron temperature exhibited its strong peak around the ECR zone near the chamber wall. A simple model indicates the mechanisms responsible for the plasma uniformity obtained: the plasma was dominantly produced around the ECR zone, and then diffused preferentially toward the center of the chamber because of strong magnetic fields generated near the wall surface.

In situFourier transform infrared (FTIR) absorption spectroscopy has been used to detect reaction products resulting from the etching of Si in Cl2plasmas. Silicon tetrachloride SiCl4was the only gas-phase product species detected during etching. Unsaturated silicon chlorides SiClx(x=1-3) were not observed in the plasma within the present level of detection. By comparing the absorbances of SiCl4in Cl2plasma etching of Si and in pure SiCl4gases, it is suggested that the concentrations of SiCl4or product species during etching are comparable to the feedstock Cl2gas densities, e.g., [SiCl4] ?1 ×1013cm-3at a pressure of 0.5 mTorr. In contrast, on the surface-etched Si, unsaturated silicon chlorides SiClx(x=1-3) as well as SiCl4were found to occur by FTIR reflection absorption spectroscopy (RAS). Moreover, absorption features of silicon oxides were observed both in the gas phase and on the surface, presumably arising from reactions between Si produced from etching and oxygen included in the reactor chamber owing to a small leak.

The properties of platinum etching were investigated using both rf magnetron and electron cyclotron resonance plasmas, together with measurement of the plasma parameters. Experiments were performed over a wide pressure range from 0.4 to 50 mTorr in Cl2plasmas. In rf magnetron plasmas, the etch rate of Pt was constant at the substrate temperature from 20 to 160°C. The etch rate and the plasma electron density increased with decreasing gas pressure from 50 to 5 mTorr. In ECR plasmas for rf power of 300 W, the etch rate of Pt was almost constant (?100 nm/min) with decreasing gas pressure from 5 to 0.4 mTorr, while the plasma electron density was gradually increased with decreasing gas pressure. These experimental results were discussed with respect to the relationship between the etch yield and ratio of neutral Cl flux and ion flux incident on the substrate. Submicron patterning (0.5 µm lines & spaces) of platinum masked with photoresist was demonstrated using Cl2plasmas in ECR discharges. High accuracy was obtained with no undercutting.

Ion trajectories near a submicron-patterned surface were investigated using numerical simulations including the effects of local charging on the patterned surface and ion drift velocity toward the wafer. The simulation results were also discussed relative to the etched profile characteristics in electron cyclotron resonance (ECR) plasmas with a divergent magnetic field. Since the pattern size was much smaller than the Debye length, charge neutrality was not satisfied on the submicron-patterned surface. The simulated ion trajectories were largely deflected at the inside of the outermost lines of line-and-space patterns. Moreover, the ion trajectory deflection was reduced with increasing ion drift velocity. These simulation results showed a similar tendency as the etching characteristics.

Electron cyclotron resonance (ECR) plasma etching of Si in Cl2has been studied from the viewpoint of plasma chemistry. Experiments were performed over a wide pressure range (0.2-10 mTorr), using a divergent magnetic-field ECR plasma reactor supplied with 2.45-GHz microwaves; a floating electrode or substrate holder was located ?30 cm downstream (B?150 G) of the 875-G ECR resonance region, and samples of polycrystalline Si were etched with no additional wafer biasing. Several diagnostics were employed to characterize the plasma around the wafer position, including two-photon laser-induced fluorescence (LIF) for detection of Cl atoms and Fourier transform infrared (FTIR) absorption spectroscopy for etch products or SiClx(x=1-4) molecules. The Si etch rate behavior obtained is interpreted in terms of a modified adsorption-reaction-ion-stimulated desorption process model based on these diagnostics.