Argon Ion Plasma Research Articles

Plasma Oxygen Interaction with Organic Polymer Films: A Mechanistic Study

In this presentation, first principles calculations combined with advanced surface diagnostics are used to unravel the mechanisms of plasma oxygen interaction with organic films, of interest for advanced patterning in semiconductor device manufacturing. Results from a combination of X-ray photoelectron spectroscopy (XPS) diagnosed oxygen plasma-exposed polystyrene films and first principles modeling of organic films (polystyrene, polyethylene and derivatives) provide insights into how organic films are oxidized by oxygen atoms. XPS measurements show the rapid formation of C-O structures and their saturation after oxygen exposure on both pristine and argon bombarded polystyrene samples. Quantum mechanics calculations confirm that C-OH formation can be immediate without recourse to previously formed dangling bonds. Multiple oxygen impacts are required for scission of pristine ethylene carbon strands. Therefore, ethylene films can be converted to polyols that are stable, whereas more likely strands are broken before polyol formation through the formation of water and C=O. On the contrary, intermediate compounds with adjacent C=O bonds are not likely to form stable structures. The combination of XPS measurements and modeling imply that the oxidation of polystyrene and polyethylene is self-limiting on both hydrogen saturated and de-hydrogenated (after argon ion plasma bombardment) surfaces.

Interaction of oxygen with polystyrene and polyethylene polymer films: A mechanistic study

In this work, first principles calculations combined with advanced surface diagnostics are used to unravel the mechanisms of plasma oxygen interaction with organic films of interest for advanced patterning in semiconductor device manufacturing. Results from a combination of x-ray photoelectron spectroscopy (XPS) diagnosed oxygen plasma exposed polystyrene films and first principles modeling of organic films (polystyrene, polyethylene, and derivatives) provide insights into how organic films are oxidized by oxygen atoms. XPS measurements show the rapid formation of C-O structures and their saturation after oxygen exposure on both pristine and argon bombarded polystyrene samples. Quantum mechanics calculations confirm that C-OH formation can be immediate without recourse to previously formed dangling bonds. Multiple oxygen impacts are required for scission of pristine ethylene carbon strands. Therefore, ethylene films can be converted to polyols that are stable, whereas more likely strands are broken before polyol formation through the formation of water and C=O. On the contrary, intermediate compounds with adjacent C=O bonds are not likely to form stable structures. The combination of XPS measurements and modeling implies that the oxidation of polystyrene and polyethylene is self-limiting on both hydrogen saturated and dehydrogenated (after argon ion plasma bombardment) surfaces.

NBR surface modification by Ar plasma and its tribological properties

Purpose – The purpose of this paper is to study the possibility and validity of using radio frequency (RF) power argon (AR) ion plasma treatment to modify the surface of nitrile butadiene rubber (NBR) and the change in the chemical structure under various bias voltage. Using wear test, the authors also compared the friction and wear properties of untreated and treated NBR. Design/methodology/approach – The hybrid RF-power sputtering system was used to generate RF Ar plasma to modify the surface of NBR specimens. The tribological properties were evaluated by ball-on-disc test using a load cell mounted on the ball holder. Findings – It was found that the NBR surface treated by the Ar plasma improved the wettability, friction and wear performance than the untreated NBR. The ATR-IR analysis indicated that the improvement come from the oxygen based functional groups generated on the surface of NBR. The improvement of friction and wear resistance may also come from the formation of nanostructure surface. Originality/value – In this study, the authors develop the RF AR ion plasma treatment at different bias voltage, and it has been used to modify the surface of NBR to increase the tribological performance.

Surface Modification of Polymer Nanocomposites by Glow-Discharge Plasma Treatment

A systematic study was carried out to characterize the effects of Argon-ion plasma on nanocomposite polymer membrane. Nanoparticles of cobalt (Co) are synthesized by the chemical root. Nanocomposite polymeric membranes 20 μm in size were prepared by using solution casting and spin coating method. The argon-ion plasma treatment was done for these membranes. The membranes were characterized prior to and after plasma treatment to perform the comparative study by using different techniques, such as the optical microscopy, scanning electron microscopy, and Fourier-transform infrared spectroscopy. The results show that the plasma treatment is a quite efficient tool for improving the surface and chemical properties of composite membranes with unique characteristics.

Effect of ion-plasma treatment on oxidation-reduction processes in lithium-titanium-zinc ferrites

We examined the effect of nitrogen, oxygen and argon plasma on the diffusion- controlled oxidation-reduction processes in lithium-titanium-zinc ferrite ceramics by measuring the activation energy of electrical conductivity in the depth of the sample. The experimental results show that the high-temperature treatment in polycrystalline ferrites by nitrogen or argon ion plasma greatly accelerates the oxidation-reduction processes in ferrites and changes the process direction depending on the partial pressure of oxygen.

Surface Modification Of Nanocomposite Polymer Membranes By Ion Plasma Irradiation For Improving Biocompatibility Of Polymer

Polymers are receiving great interest due to their increasing applications in various fields, especially for synthesis of biomaterial. Biomaterials are nonviable materials used in medical devices, intended to interact with biological systems. To use polymer as biomaterial they required properties like antibacterial, antimicrobial, high adhesion and wettability. Low temperature plasma treatment can offer these properties to polymers. Hence a systematic study was carried out for determining the effect of ion plasma treatment on nanocomposite polymer membranes. TiO2 nanoparticles having particle size 10-16 nm were synthesized by chemical method and used for preparation of nanocomposite polymer membranes. Argon ion plasma was used for modified polymer surface. These membranes were characterized by different techniques to identify surface and chemical modification. FTIR results shown significant modification in chemical properties, while SEM images shows increase in surface roughness of nanocomposite polymer membranes after plasma treatment. Bacterial cell adhesion and wettability were also found to be increased after plasma treatment.

Fabrication and adhesion of hierarchical micro-seta

Spark-erosion perforating technology was used to fabricate a Cu-based template characterized by pores with radius of 0.5 mm inclined at 75°. A commercial silicone elastomer of poly(dimethylsiloxane) (PDMS) with a rich Si-H content was used to produce an inclined array of primary setae. The technique of argon ion plasma etching on crystalline silicon was used to fabricate negative templates with radii of 5, 10, and 20 μm. The Si-H rich PDMS was used to cast three types of fine array templates, which acted as the secondary setae. A vinyl-rich PDMS precursor was used to bind the primary and secondary setae by a hydrosilylation reaction, thus allowing the formation of three different hierarchical arrangements of setae. Adhesion tests demonstrated that shear adhesion was anisotropic, first increasing in strength then decreasing to a stable level as slippage occurred. The adhesion strength was significantly influenced by the nature of the secondary setae, showing a strong correlation with aspect-ratio and concentration.

Suppression of leakage currents in InAsSb MWIR photodiodes by chemical treatment and illumination

Novel surface treatments for an InAs0.91Sb0.09 p–n junction grown on GaSb by MOCVD are proposed and demonstrated. Exposure of the p–n junction to argon ion plasma followed by etching with tartaric acid reduces the dark currents by five orders of magnitude. An additional reduction by two orders of magnitude in the dark current is achieved by illuminating the sample with white light. A mid-wavelength infrared photodetector based on the so treated p–n junction exhibits a high zero-bias resistance–area product (R0A) of 2.7 × 107 Ω cm2 and an internal quantum efficiency of 70% at 77 K. The measured BLIP temperature is 170 K and a high detectivity value (D* BLIP) of 4.03 × 1011 cm Hz1/2 W−1 is observed at 3.7 µm. The surface treatment results indicate that the device performance is limited by bulk material properties.

S180 cell growth on low ion energy plasma treated TiO 2 thin films

X-ray photoelectron spectroscopy (XPS) was used to characterise the effects of low energy (<2 eV) argon ion plasma surface modification of TiO 2 thin films deposited by radio frequency (RF) magnetron sputter system. The low energy argon ion plasma surface modification of TiO 2 in a two-stage hybrid system had increased the proportion of surface states of TiO 2 as Ti 3+. The proportion of carbon atoms as alcohol/ether (C OX) was decreased with increase the RF power and carbon atoms as carbonyl (C O) functionality had increased for low RF power treatment. The proportion of C( O)OX functionality at the surface was decreased at low power and further increase in power has showed an increase in its relive proportion at the surface. The growth of S180 cells was observed and it seems that cells are uniformly spreads on tissue culture polystyrene surface and untreated TiO 2 surfaces whereas small-localised cell free area can be seen on plasma treated TiO 2 surfaces which may be due to decrease in C( O)OX, increase in C O and active sites at the surface. A relatively large variation in the surface functionalities with no change in the surface roughness was achieved by different RF plasma treatments of TiO 2 surface whereas no significant change in S180 cell growth with different plasma treatments. This may be because cell growth on TiO 2 was mainly influenced by nano-surface characteristics of oxide films rather than surface chemistry.

In situ silicon-wafer temperature measurements during RF argon-ion plasma etching via fluoroptic thermometry

In situ silicon-wafer temperature measurements during RF argon-ion plasma etching are reported for four different wafer cooling environments: (i) lying on the electrode; (ii) clamped to the electrode; with additional helium gas between wafer and electrode in both (i) and (ii), in order to enhance heat transfer. Fluoroptic thermometry is applied to measure the local surface temperature of the wafer during plasma processing. The measured heating and cooling curves can be fitted using a model which considers conductive heat losses only. Deviations are observed when high RF power is applied and surface temperatures higher than 120 degrees C are reached. The authors report on effective cooling via helium gas of the rear side of the wafer which is lying on an electrode without any clamping.

Steady-state magnetized non-neutral ion plasma

A steady-state dense non-neutral argon-ion plasma, confined radially by a strong uniform axial magnetic field (max 0.1 Wb/m2), has been generated to a density ∼1014/m3. The radial density profile of argon ions has been measured using a Langmuir probe. The dependence of the ion number density on the axial magnetic field has been observed.

Three-mirror stable resonator for high power and single-mode lasers

A stable, high Q, three-mirror resonator is proposed for the optimum output coupling and mode control of high power moderate-gain lasers. Theoretical calculations on the beam intensity distributions, spot sizes, and stability conditions are given. Alignment tolerance for a limiting case is discussed. Experimental results with a high power argon-ion plasma tube and a three-mirror stable resonator agree with the theory.