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Silicon dioxide films were grown using an atmospheric-pressure plasma jet that was produced by flowing oxygen and helium between two coaxial metal electrodes that were driven by 13.56 MHz radio frequency power. The plasma exiting from between the electrodes was mixed with tetraethoxysilane (TEOS), and directed onto a silicon substrate held at 115-350 °C. Silicon dioxide films were deposited at rates ranging from 20±2 to 300±25 nm min-1. The deposition rate increased with decreasing temperature and increasing TEOS pressure, oxygen pressure and RF power. For the latter two variables, the rate increased as follows: Rd∝P0.3O2(RF)1.4. Films grown at 115 °C were porous and contained adsorbed hydroxyl groups, whereas films grown at 350 °C were smooth, dense and free of impurities. These results suggest that the mechanism in the atmospheric pressure plasma is the same as that in low-pressure plasmas.

Tantalum was etched in a downstream, atmospheric-pressure plasma. In this process, etching occurred without significant ion bombardment. An etching rate of 6.0±0.5 μm/min was achieved using 14.8 Torr oxygen, 22.4 Torr carbon tetrafluoride, 720±5 Torr helium, 685 W radio frequency power at 13.56 MHz, and a film temperature of 300 °C. The etching rate increased with the applied power, carbon tetrafluoride pressure, oxygen pressure, and residence time of the gas between the electrodes, indicating that the surface reaction depends on the density of reactive fluorine species generated in the plasma. X-ray photoemission spectroscopy revealed that the etched surface was covered with tantalum fluoride and to a lesser extent, tantalum oxide. Based on these observations, a mechanism for tantalum etching is proposed which involves the reaction between fluorine atoms and the adsorbed tantalum fluoride.

The reaction chemistry in the afterglow of a non-equilibrium, capacitive discharge, operated at 600 Torr total pressure with (0.5 to 5.0) × 1017 cm-3 of oxygen in helium, has been examined by ultraviolet absorption spectroscopy, optical emission spectroscopy, and numerical modeling. The densities of the active species, O(3P), O2(1Δg), O2(1Σg+), and O3, have been determined as a function of the operating conditions. At RF power densities between 6.1 and 30.5 W/cm3 and a neutral temperature of 100 ± 40 °C, the plasma generated (0.2 to 1.0) × 1016 cm-3 of O(3P) and O2(1Δg), (0.2 to 2.0) × 1015 cm-3 of O2(1Σg+), and (0.1 to 4.0) × 1015 cm-3 of O3. After the power was turned off, the singlet-sigma and singlet-delta states decayed within 0.1 and 30.0 ms, respectively. The concentration of oxygen atoms remained constant for about 0.5 ms, then fell rapidly due to recombination with O2 to form O3. It was found that the etching rate of polyimide correlated with the concentration of oxygen atoms in the afterglow, in...

An atmospheric-pressure plasma jet has been used to etch polyimide films at 1.0–8.0±0.2 μm/min at 760 Torr and between 50 and 250 °C. The plasma was produced by flowing helium and oxygen between two concentric electrodes, with the inner one coupled to 13.56 MHz rf power and the outer one grounded. The etch rate increased with the O2 partial pressure, the rf power and the substrate temperature. The apparent activation energy for etching was 0.16 eV. Langmuir-probe measurements revealed that the ion densities were between 1×1010 and 1×1011 cm−3, 5 mm from the end of the powered electrode. Biasing the substrate had no effect on the rate. Ozone, singlet sigma metastable oxygen (b 1Σg+), and singlet delta metastable oxygen (a 1Δg) were detected in the plasma by emission spectroscopy. More ozone was produced in the effluent through the recombination of O atoms with O2. Based on the production rate of O3, the concentration of O atoms 6 mm from the powered electrode was estimated to be ∼7×1014 cm−3 at 6.6 Torr O2...

A plasma jet has been developed for etching materials at atmospheric pressure and between 100 and C. Gas mixtures containing helium, oxygen and carbon tetrafluoride were passed between an outer, grounded electrode and a centre electrode, which was driven by 13.56 MHz radio frequency power at 50 to 500 W. At a flow rate of , a stable, arc-free discharge was produced. This discharge extended out through a nozzle at the end of the electrodes, forming a plasma jet. Materials placed 0.5 cm downstream from the nozzle were etched at the following maximum rates: for Kapton ( and He only), for silicon dioxide, for tantalum and for tungsten. Optical emission spectroscopy was used to identify the electronically excited species inside the plasma and outside in the jet effluent.

A plasma jet has been developed which deposits silica films at up to at 760 Torr and 115 to C. The jet operates by feeding oxygen and helium gas between two coaxial electrodes that are driven by a 13.56 MHz radio frequency source at 40 to 500 W. Tetraethoxysilane is mixed with the effluent of the plasma jet and directed onto a substrate located 1.7 cm downstream. The properties of the silica films, as determined by infrared spectroscopy and capacitance measurements, are comparable to those of thermally grown silicon dioxide films at C.