Comparison of etching of different polymers in an oxygen plasma was studied. The plasma was created in an electrodeless radiofrequency discharge at a frequency of 27.12 MHz and a power of 200 W. Oxygen pressure was fixed at 75 Pa. The degradation of the polymers by oxidation with plasma particles was monitored by measuring the weight loss of the polymer samples. The samples were weighed just before mounting into the plasma reactor, and then again just after the plasma treatment. The following polymers were used in this study: PET (amorphous and semicrystalline), PMMA, PS, LDPE, HDPE, PVC and PTFE. When comparing etching rates of different polymers we could not find any good correlation between the chemical structure of polymers and their etching rates. The polymer etching rate was linearly increasing with treatment time. This was explained by the heating of the samples during plasma treatment.
COBISS.SI-ID: 26023207
Films of polyethylene terephthalate were deposited on quartz crystals and exposed to oxygen atoms to study their etching characteristics and quantify the etching rate. Oxygen (O) atoms were created by passing molecular oxygen through plasma created in a microwave discharge. The discharge power was fixedat 250 W, while the pressure of oxygen was 50 Pa. Before exposure to oxygen atoms, a thin polymer film of polyethylene terephthalate (PET) was deposited uniformly over a crystal with a diameter of 12 mm. The crystal was mounted on a quartz crystal microbalance to accurately determine the thickness of the polymer film. The polymer film was exposed to O atoms in the flowing afterglow. Samples were treated with O atoms for different periods of up to 120 min. The thickness of the film decreased linearly with treatment time. After 90 min of treatment, a 65-nm-thick polymer film was completely removed. Therefore, the etching rate was 0.5 nm/min, so the interaction probability between an O atom and an atom in the sample was extremely low, just 1.4x10-6. Samples treated for different periods were investigated by atomic force microscopy and X-ray photoelectron spectroscopy to examine the etching characteristics of O atoms in the flowing afterglow.
COBISS.SI-ID: 16102166
The presented sensor for neutral oxygen atom measurement in oxygen plasma is a catalytic probe which uses fiber optics and infrared detection system to measure the gray body radiation of the catalyst. The density of neutral atoms can be determined from the temperature curve of the probe, because the catalyst is heated predominantly by the dissipation of energy caused by the heterogeneous surface recombination of neutral atoms. The advantages of this sensor are that it is simple, reliable, easy to use, noninvasive, quantitative and can be used in plasma discharge regions. By using different catalyst materials the sensor can also be applied for detection of neutral atoms in other plasmas. Sensor design, operation, example measurements and new measurement procedure for systematic characterization are presented.
COBISS.SI-ID: 25707047