The physics of an atmospheric pressure, radio frequency plasma has been investigated. The discharge is generated with helium and 0.4 vol.% nitrogen passing between two metal electrodes with a 3.0-mm gap. It was discovered that at a critical power density of 2.1 kW/cm/sup 3/, the plasma undergoes sheath breakdown and transitions from the /spl alpha/- to the /spl gamma/-mode. Photographs are presented showing the unique distribution of excited-state species under these conditions.

Summary form only given. A new atmospheric pressure plasma source has been developed that shows exceedingly high processing rates. For example, kapton films have been etched at 5.0 mum/s using an argon and oxygen discharge with 6.0 vol.% O2 and a temperature of 280degC. The plasma source consisted of a small quartz tube that was capacitively coupled to radio frequency power at 13.56 MHz. The input plasma power could be increased up to 150 W/cm3 without arcing, or forming a streamer like discharge. At this power density, the gas temperature was determined by spectroscopic methods to be 300plusmn30degC. The O atom concentration was measured in the plasma afterglow by nitric oxide titration, and was found to be 1.2plusmn0.6times1017 cm-3 at 150 W/cm3 and 6.0 vol.% O2 in Ar. The concentration of ozone in the downstream region equaled 4.3plusmn0.5times1014 cm -3, as determined by UV absorption spectroscopy. These results were found to be in good agreement with a numerical model of the plasma and afterglow that included the reaction mechanism and the plasma electron density and temperature as calculated from current-voltage measurements

Summary form only given. The plasma-enhanced chemical vapor deposition (PECVD) of silicon dioxide films has been examined in a low temperature, atmospheric pressure discharge. A mixture of 2.0 vol% oxygen in helium was utilized in a capacitive discharge operating at 100 W RF power and a neutral gas temperature of /spl sim/100/spl deg/C. Several silicon precursors were studied, including tetramethyldisiloxane (TMDSO), tetramethylcy-clotetrasiloxane (TMCTS), tetraethoxysilane (TEOS), and hexa-methyldisilazane (HMDSN). After growth, the thickness, refractive index and composition of the silicon dioxide films were determined by ellipsometry, Fourier-transform infrared spectroscopy and Rutherford backscattering. Abrasion tests were performed on films deposited on plastic substrates. Glass films could be deposited at rates up to 1.0 micron/minute using TMDSO. However, these films contained 5.0 to 10.0 atom% carbon and hydrogen, and abraided easily during scratch tests. Feeding HMDSN to the oxygen plasma resulted in the deposition of silicon dioxide films that were free of nitrogen and carbon (<0.5 atom%), contained /spl sim/2.0 atom% hydrogen, and displayed excellent scratch resistance. The maximum deposition rate obtained using HMDSN was 0.3 microns/minute. It was found that the deposition rate increased with RF power, oxygen partial pressure up to 10 Torr, and decreasing distance between the plasma source and substrate (2.0 to 10.0 mm). At the meeting, we will discuss the relationship between the plasma chemistry and the properties of the silicon dioxide coatings.

Summary form only given. Non-equilibrium atmospheric pressure plasmas are of interest for the surface treatment, cleaning, etching and deposition of materials. We have characterized the properties of a radio-frequency atmospheric pressure plasma fed with helium or argon and up to 2.0 vol% nitrogen. The electrodes consisted of two parallel plates, 0.5 cm/sup 2/, separated by a gap of 1.6 mm. At a current and voltage of 0.26 A and 229 V, the gas undergoes partial ionization, entering the abnormal glow regime. The current and voltage increased with the applied power to maximum values of 0.41 A and 317 V. The power consumed by the plasma at this point was 2.4 W. Further increasing the power caused the plasma to shift into a new discharge mode, in which one of the sheaths appeared to break down. Here the current and voltage ranged from 0.33 to 0.27 A and 202 to 220 V before it returned to the abnormal mode with decreasing power. In this mode, the maximum power consumed by the plasma was 50 W. The density of nitrogen atoms produced in the abnormal and high-power glow discharges was determined by measuring the temporal decay rate of the first-positive emission of nitrogen molecules, i.e., N/sub 2/(B)/spl rarr/N/sub 2/(A)+h/spl nu/. It was found that the abnormal glow at 30 W/cm/sup 3/ and 1.3 vol% N/sub 2/ in He produced 1.0/spl times/10/sup 16/ cm/sup -3/ N atoms. This corresponded to dissociation of 1.7% of the N/sub 2/ molecules. By contrast, the high-power mode with a maximum power density of 2600 W/cm/sup 3/ and 0.4 vol% N/sub 2/ in He generated 1.7/spl times/10/sup 16/ cm/sup -3/ N atoms. This is equivalent to 8.4% dissociation of the N/sub 2/. Note that the neutral gas temperature measured in the abnormal and high-power glow discharges equaled 75 and 250/spl deg/C, respectively. These results indicate that both operating modes of the plasma are effective at dissociating molecules into reactive species. A thorough discussion of the physics and chemistry of the atmos- heric plasma will be provided at the meeting.

Summary form only given. In this paper, a low temperature, atmospheric pressure plasma source has been examined for the isotropic etching of photoresist, glass and metal film. In addition, the system has been configured for remote plasma enhanced chemical vapour deposition of silicon dioxide, silicon nitride and amorphous hydrogenated silicon.