Plasma Source Ion Implantation Research Articles

Investigation of diamond-like carbon formed on PET film by plasma-source ion implantation using C 2H 2 and CH 4

The characteristics of amorphous carbon films deposited on polyethylene terepthalate (PET) film by plasma-source ion implantation (PSII) using C 2H 2 and CH 4 gases are examined. PSII is performed using a pulsed, high negative bias (∼9 kV, ∼10 μs pulse width, 300 pulses/s) to form the self-excited discharge for processing. The use of CH 4 at lower gas pressure modified the PET film by direct implantation of carbon atoms to form a mixing layer with high C–H bond density, in contrast to formation using C 2H 2 which forms a surface coating of amorphous carbon. At higher gas pressure, CH 4 was found also to produce a surface layer of amorphous carbon. The films produced using CH 4 were found to consist primarily of hydrogenated graphite crystal with C–H, C–H 2 and C–H 3 components. The oxygen transmission rates (OTR) of PET treated with CH 4 were reduced by a factor of 50–70 from that of untreated PET at a carbon film thickness of only ∼50 nm, however the transmission rate reduction per unit thickness of film was lower than for films formed using C 2H 2. The surface modification with CH 4 is a viable alternative method for reducing the OTR. The relationships between the gas conditions and the properties of the carbon films are discussed.

Deposition of diamond-like carbon films on inner wall of sub-millimeter diameter steel tube by plasma source ion implantation

Diamond-like carbon (DLC) films were deposited on the inner wall surface of 304 austenitic type stainless steel tubes with inner diameter of 0.9 and 0.5 and 15 mm length by a plasma source ion implantation (PSII). A 2.45 GHz microwave was fed into a tubular vacuum chamber and supplied to an antenna. An acetylene gas was fed into the alumina ceramic tube. Plasma was produced by a coaxial electron cyclotron resonance (ECR) discharge. A magnetic field of one kilogauss was generated by a solenoidal coil. The negative high voltage pulse (typically −10 kV, 1 kHz, 10 μs) was applied to the steel tube. The results showed that the DLC film deposition on the inner wall of sub-millimeter size steel tubes was achieved by the PSII. Raman spectra of the DLC films showed a broad peak related to amorphous carbon structure.

Measurement of expanding plasma sheath from a target biased by a negative pulse with a fast rise time

The pulse rise time effect on sheath size is investigated. Experiments are carried out on a planar target biased by a negative pulse with a fast rise time in a plasma source ion implantation (PSII) system. The fast rise time of the pulse provides that the speed of sheath expansion is larger than the Bohm speed during the pulse rise time. Results show that the sheath size increases with increasing pulse voltage and pulse rise rate (the ratio of the pulse voltage and the rise time), which is a very important factor for characterizing the expanding sheath in PSII. During the rise time, sheath size is proportional to the square root of the pulse rise rate over plasma density but it is insensitive to ion mass. Experimental results are in good agreement with the developed model based on the expanding ion matrix sheath model. After the full pulse has been attained, the sheath increases linearly with a constant speed as the Bohm speed.

Plasma source ion implantation near the end of a cylindrical bore using an auxiliary electrode for finite rise time voltage pulses

The temporal evolution of the plasma sheath during plasma source ion implantation(PSII) is crucial because it affects the resultant surface properties and structures. In this paper two dimensional fluid model is applied to the problem in computing ion dynamics in the sheath of the end of a cylindrical bore using an auxiliary electrode for finite rise time voltage pulses. The ion density, flux, dose distributions are calculated by solving Poisson's equation and the equations of ion motion and continuity using finite difference methods. Our results indicate that there exist the differences of ion flux and dose among the inner, outer surfaces and the end surface of the bore.

不活性ガスを用いたプラズマソースイオン注入（ＰＳＩＩ）法による滅菌プロセス

Plasma source ion implantation (PSII) with high negative pulsed voltage applied to the workpiece is demonstrated as an effective low-temperature sterilization technique for three-dimensional work pieces. Using an N2 or Ar gas plasma and a pulsed voltage of -5 to -16 kV (10 μs pulse width, 900 pps), the method is shown to reduce the number of active Bacillus Pumilus spores by 3-5 log colony forming units after 15 min exposure.

TiN coating for inner surface modification by grid enhanced plasma source ion im plantation

Using the new inner surface modification technique named GEPSⅡ(grid-enhanced pl asma source ion implantation), which is designed for inner surface modification of tubular work piece, has successfully produced TiN coating on 0.45% C steel (4 5# steel). By comparing with the uncoated 45# steel sample, the electrochemical corrosion test on the coated 45# steel samples presents about 5—10 times improv ement in their corrosion resistance. Structural analysis shows that the TiN coat ings have preferred crystal orientation(111) and (2000). And the depth of coatin gs is about 20 nm, with part of which embedding in the substrate.

Adhesion Mechanism at Metal-Organic Interface Modified by Plasma

Mold die sticking has been thought to be caused by the increase in die surface roughness and surface area due to silica filler abrasion. Insitu results of semiconductor manufacturers showed a strong dependency on the make of EMC (epoxy molding compound); indicating chemical interaction was apt to be also functioning as a major mechanism. PSII (plasma source ion implantation) using O 2 , N 2 , and CF 4 was applied to modify sample surface condition from hydrophilic to hydrophobic and vice versa. By comparing surface energy quantified by contact angle and surface ion coupling state analyzed by Auger with pull-out strength, the governing mechanism for the sticking issue was determined to be a result of complex of mechanical and chemical factors.

Preparation and Properties of Diamond-Like Carbon by Plasma Source Ion Implantation

Preparation and Properties of Diamond-Like Carbon by Plasma Source Ion Implantation

Amorphous carbon layer deposition on plastic film by PSII

Plasma-source ion implantation (PSII) is successfully employed without an external radio frequency plasma source to form a thin amorphous carbon layer on the surface of polyethylene terepthalate (PET) film by applying pulsed high negative voltage (∼10 μs pulse width, 300–900 pulses/s, −10 kV) to a sample immersed in C 2H 2 gas with and without Ar. This pulsed voltage condition is found to itself generate a plasma surrounding the substrate and PET film to form a thin carbon layer. The oxygen barrier characteristics of the PET were improved remarkably by this PSII processing, and laser Raman, X-ray photoelectron and Fourier-transform infrared spectroscopy spectra revealed that the thin amorphous carbon layer was found to consist primarily of graphite crystal with the characteristics of diamond-like carbon. The ratio of sp 2 (graphite) to sp 3 (diamond) populations was found to vary according to the gas pressure of C 2H 2 and the addition of Ar, which affects on the oxygen barrier characteristics.

Structural characterization of various ionomers by time-of-flight secondary ion mass spectrometry

To investigate the wetting properties of the copolymers and ionomeric materials, a series of ionomers were synthesized, i.e., poly(styrene-co-acrylate) ionomers. Copolymers and ionomers were modified by plasma source ion implantation (PSII) and their surfaces were characterized by using contact angle measurement and time-of-flight secondary ion mass spectrometry (TOF-SIMS). PSII-treated ionomers provide more hydrophilic and stable surfaces with aging time than untreated ionomers and treated copolymers. Thus, it was concluded that the presence of ionic groups and the ionic interaction between the ionic groups resulted in very hydrophilic surfaces and the slow hydrophobic recovery. TOF-SIMS was used to analyze the copolymer and ionomer surfaces, in order to obtain the fundamental information on the chemical structure and surface properties.

Surface characterization of NiTi modified by plasma source ion implantation

This paper reports the novel application of an oxygen ion plasma for surface modification of a shape memory alloy. The surface characterization of oxygen ion implanted Ti–50.7 at% Ni alloy samples was performed with the assistance of Auger electron spectroscopy, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy techniques (TEM). TEM identified amorphous TiO 2 and crystalline phases of Ti 11Ni 14 and Ti 4Ni 2O x . XPS results reveal that the surfaces of control samples are covered with predominantly TiO 2 and traces of TiO and NiTi, as well as NiO and Ni 2O 3. At the surface of oxygen-implanted samples, however, only TiO 2 and trace amounts of Ni 2O 3, NiO and NiTi were observed. TiO and NiO exist in much larger range than other oxides, and TiO extends to the oxide–metal interface. These results are especially noteworthy because of their implications for interpreting corrosion, wear, and biocompatibility behavior.

Pulsed Ion Sheath Dynamics in a Cylindrical Bore for InnerSurface Grid-Enhanced Plasma Source Ion Implantation

Based on our recently proposed grid-enhanced plasma sourceion implantation (GEPSII) technique for inner surface modification ofmaterials with cylindrical geometry, we present the correspondingtheoretical studies of the temporal evolution of the plasma ion sheathbetween the grid electrode and the target in a cylindrical bore. Typicalresults such as the ion sheath evolution, time-dependent ion densityand time-integrated ion energy distribution at the target are calculatedby solving Poisson's equation coupled with fluid equations forcollisionless ions and Boltzmann assumption for electrons using finitedifference methods. The calculated results can further verify thefeasibility and superiority of this new technique.

Improvement of oxygen barrier of polyethylene terepthalate film by plasma-source ion implantation of carbon

The surface of polyethylene terepthalate (PET) film has been successfully modified to amorphous carbon by plasma source ion implantation (PSII) as a means of improving the oxygen barrier characteristics of the PET film. The process was performed using high negative pulsed voltage in an radio frequency field with C2H2 gas. The amorphous carbon layer is found to consist primarily of graphite crystal with C–H, C–H2 and C–H3 components, and to reduce the oxygen transmission rate of the film by up to 100 times that of unmodified PET film at a thickness of only 70–300 nm. Raman spectra reveal that the amorphous carbon layer has diamond-like carbon characteristics, yet is soft compared to other diamond-like carbon films with hydrogen contents of >20 at. %. A stronger graphite character in the x-ray photoelectron spectroscopy spectra is found to represent the fineness of the carbon structure and correlate well with the improvement of oxygen barrier characteristics.

Reduction in surface resistivity of polymers by plasma source ion implantation

The surface resistivity of several polymers such as poly(styrene/butadiene copolymer), modified poly(phenyleneoxide), poly(ethylene terephthalate), and polyimide was improved by the argon gas plasma source ion implantation (Ar-PSII) technique equipped with a mesh-type conducting grid. With the grid, the surface resistivities of the modified polymers decreased up to 11 orders of magnitudes at a high ion dose, and remained nearly at the same values after 3 months. The PSII treated polymer sample with the grid provided more uniformly modified surface and lower surface resistivity than that treated without the grid. The extent of the decrease in surface resistivity depended on the polymer structures and physical properties. However, the surface resistivity was independent of the sample thickness, the grid size, and the grid height. Surface analyses using scanning electron microscopy, time-of-flight secondary ion mass spectrometry, and Raman spectroscopy provided the useful information on modified surfaces.

Surface analysis of polymers electrically improved by plasma-source ion-implantation.

Inert-gas (Ar, Xe) and reactive-gas (O(2), N(2)) plasma-source ion-implantation (PSII) treatment of PI, PET, PS-BD, and MPPO surfaces was performed at an ion energy of 30 keV to improve the electrical properties of the polymers. The effect of ion energy, treatment time, rf frequency, and power on the surface resistivity of polymer was investigated. Depending on ion energy, dose, and ion species, the surface resistivity of the film was reduced by several orders of magnitude. XPS, TOF-SIMS, and SEM were used to characterize MPPO surfaces treated by Ar-PSII and Xe-PSII. From these measurements it was found that the improvement in surface resistivity after PSII treatment was related to graphite carbon or cross-linked carbon-double-bond species formed on the surface.

Preparation of plastic and biopolymer multilayer films by plasma source ion implantation.

The plasma source ion implantation (PSII) technique was used to improve the adhesion between linear low-density polyethylene (LLDPE) and biopolymer. LLDPE was treated with the PSII using O(2) or CF(4) gas to modify its surface. After modification, chitosan or corn zein was used for coating on LLDPE. Wettability of the LLDPE surface was evaluated with a contact angle meter by the sessile drop method. X-ray photoelectron spectroscopy (XPS) was used to analyze the LLDPE surface. Before and after treatment, in the case of LLDPE treated with O(2) PSII, oxygen-containing functional groups were formed on the implanted surface. In the CF(4) PSII treated LLDPE, it was observed that the fluorine concentration on the surface of LLDPE remarkably increased and hydrophobic groups were formed by chemical reaction. Bilayer films coated with chitosan or corn zein showed 10 times lower oxygen permeability. Tensile strength of multilayer films was decreased a little compared with that of LLDPE. The plastic and biopolymer multilayer films have potential for food packaging application because of their O(2) gas barrier property and easy recyclability of the multilayer film.

Ion implantation into inner wall surface of millimeter size diameter steel tube by plasma source ion implantation

Nitrogen and carbon ions were implanted into the inner wall surface of 304 austenitic type stainless steel and Ni tubes with inner diameters of 0.9, 2 and 1.6 mm, by a plasma source ion implantation (PSII). These 30 mm long substrate tubes were fixed to an alumina ceramic tube in a vacuum chamber, fed with nitrogen and acetylene gases. A 2.45 GHz microwave was supplied to an antenna in the alumina ceramic tube and plasma was produced by a coaxial electron cyclotron resonance (ECR) discharge in this tube. A negative high voltage pulse of 15 kV (1 kHz, 10 μs) was applied to the steel and Ni tubes to extract ions from the generated plasma. The compositional and structural characterizations of the implanted surfaces were carried out using Auger electron spectroscopy and Raman spectroscopy. The results showed that uniform nitrogen ion implantation into the millimeter size inner wall surface of metal tubes was achieved by the PSII. Carbon implantation and subsequent diamond like carbon (DLC) coating was confirmed for the inner wall surface treated by acetylene PSII.

Preparation and properties of metal containing diamond-like carbon films by magnetron plasma source ion implantation

Metal-containing diamond-like carbon (DLC) films were prepared on silicon wafer substrate by a process combining reactive magnetron sputtering with plasma source ion implantation (PSII). Ti and Ta were deposited simultaneously by RF magnetron sputtering of metal target and PSII using hydrocarbon gas, respectively. Ar/C 2H 2 mixed gas was introduced into the discharge chamber. The negative high voltage pulse (typically 10 kV, 100 Hz, 100 μs) was applied to the substrate holder. The chemical composition of the films was determined using X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The surface morphology was observed by scanning electron microscopy (SEM). The film structure was characterized by Raman spectroscopy and X-ray diffractometry. The sheet resistivity of the films was measured by a four-point probe method. Furthermore, a ball-on-disc test was employed to obtain information about the frictional properties and sliding wear resistance of the films. The structure of the films changed from metal containing DLC to composite of metal containing DLC and metal carbides with increasing in metal content in the films. The sheet resistivity of the films was decreased drastically with increasing metal content in the films. The tribological properties of the films were improved by metal elements doping.

Diamondlike carbon deposition on plastic films by plasma source ion implantation

Application of pulsed high negative voltage (∼10 μs pulse width, 300–900 pulses per second) to a substrate is found to induce discharge, thereby increasing ion current with an inductively coupled plasma source. This plasma source ion beam implantation (PSII) technique is investigated for the pretreatment and deposition of diamond-like carbon (DLC) thin layer on polyethylene terepthalate (PET) film. Pretreatment of PET with N2 and Ar plasma is expected to provide added barrier effects when coupled with DLC deposition, with possible application to fabrication of PET beverage bottles. PSII treatment using N2 and Ar in separate stages is found to change the color of the PET film, effectively increasing near-ultraviolet absorption. The effects of this pretreatment on the chemical bonding of C, H, and O are examined by x-ray photoelectron spectroscopy (XPS). DLC thin film was successfully deposited on the PET film. The surface of the DLC thin layer is observed to be smooth by scanning electron microscopy, and its structure characteristics are examined by XPS and laser Raman spectroscopy. Subsequent processing using acetylene or acetylene and Ar (20%) produced thin carbon layers that are confirmed to be graphite-dominated DLC. Also, this PSII method is employed in order to deposit the DLC layer on the inside surface of the PET bottle and to reduce oxygen permeation rate by 40%.

The effect of plasma exposure and annealing atmosphere on shallow junction formation using plasma source ion implantation

The effect of recoil-implantation and out-diffusion in plasma source ion implantation (PSII) on ultra-shallow p +/n junction formation has been studied. Because the wafer is directly exposed to plasma, diborane radicals in the plasma can be adsorbed on the wafer surface. The amount of recoil-implanted boron as an additive dose was measured. In the annealing process, increasing the nitrogen pressure from vacuum to 360 torr, decreased the boron out-diffusion. In addition, increasing the annealing time rendered the boron out- and in-diffusion severe. Considering recoil implantation, the wafers were implanted with a dose of 1.98×10 15 atoms/cm 2. The as-implanted wafers were subsequently spike-annealed at 1000 °C in nitrogen ambient. With implant energy of 0.5 and 1 keV, ultra-shallow junction depths of 360 and 380 Å, respectively, could be acquired. In addition, sheet resistance of 420 and 373 Ω/□ were obtained, respectively. This junction depth and sheet resistance prepared by PSII was found to satisfy next-generation memory-device doping technology.