Plasma Immersion Ion Implantation Process Research Articles

A biocompatible nanofibers modified by plasma for osteoblast growth differentiation.

This work employs nitrogen plasma immersion ion implantation (PIII) to modify electrospinning polylactic acid membranes and immobilizes essential fibroblast growth factors(bFGF) by forming cross-linking bonds. The study investigates the modified membranes' surface characteristics and the stimulatory effects of cross-linked bFGF polylactic acid membranes on osteoblast and fibroblast proliferation. The PIII process occurs under low vacuum conditions and is controlled by processing time and power pulse width. The experimental results indicate that, within a 400-second N2-PIII treatment, the spun fibers remain undamaged, demonstrating an increase in hydrophilicity (from 117° to 38°/36°) and nitrogen content (from 0% to 7.54%/8.05%). XPS analysis suggests the formation of a C-N-C=O cross-linked bond. Cell culture and activity assessments indicate that the PIII-treated and cross-linked bFGF film exhibits significantly higher cell growth activity (P<0.05) than the untreated group. These intergroup differences are attributed to the surface cross-linking bond content. In osteogenic induction, the results for each day show that the treated group performs better. However, the intergroup disparities within the cross-linked bFGF group disappear with prolonged culture time due to the rapid osteogenesis prompted by bFGF. The findings suggest that PIII treatment of electrospinning polylactic acid membranes holds promise in promoting osteogenesis in bone tissue scaffolds.

Neuromorphic sensing of biomolecules covalently immobilised on polydimethyl glutarimide

Polydimethyl glutarimide (PMGI) layers with sub-micron thicknesses have been modified in a 2.5 kV Ar plasma immersion ion implantation (PIII) process to introduce free radical covalent binding sites. The surface roughness of the PMGI increased after the PIII treatment but no through-layer defects were observed. When applied to the treated PMGI, horseradish peroxidase (HRP) enzyme remained bound to the surface after extended immersion in sodium dodecyl sulfate solution (SDS). Hence, covalent binding between the activated surface and enzyme was confirmed. This covalent binding was achieved up to 24-h after the PIII process. The treated PMGI was then incorporated as a gate dielectric layer within a lateral three-terminal electrolyte-gated device. The device output characteristics resembled those of post-synaptic outputs; as successive (pre-synaptic) voltage pulses were applied to the gate, paired pulse depression and spike rate dependent plasticity were observed in the source-drain (post-synaptic) current. These characteristics were altered by the presence of HRP immobilised on the plasma-modified PMGI gate dielectric layer thus providing readout detection. These results and preliminary device characteristics show the potential for the plasma functionalized PMGI as a sensitive and reproducible biosensing technology.

Optical properties of plasma‐treated PEEK: Monitoring colour and crystallinity for applications in medicine and dentistry using ellipsometry

AbstractPoly‐ether‐ether‐ketone (PEEK) is a widely used and versatile polymer. Here, we use ellipsometry to determine the wavelength‐dependent optical properties of PEEK before and after the surface is modified by plasma immersion ion implantation (PIII), a technique that renders the surface hydrophilic and bio‐active. Lorentz and Gaussian oscillator models are used to fit the data for extraction of the optical constants and the dielectric function. The effect of PIII, even for short treatment times, changes the optical properties of PEEK, indicative of an amorphisation of the initial semicrystalline structure that broadens the electronic density of states distribution. The progressive changes in the optical properties with treatment time allow assessment of colour changes and estimation of ion dose in the PIII process.

Graphene-like coated steel tube via biased hollow cathode discharges

The inner surface of a narrow steel tube was coated with a very thick graphene-based (Gr-like) layer by biasing the tube in a Plasma Immersion Ion Implantation and Deposition (PIII&D) process. The outcomes indicate that a multilayer graphene film was grown in well-aligned columnar structures, showing a typical cauliflower-like character. Local gas feeding was found not only to overcome the discharge breakdown in such a small tube, but it additionally leads to a completely different supply of carbon species. In this sense, Gr-like coated tubes could extend the applicability of PIII&D process to attend other engineered applications.

Exploration of Solid Phase Epitaxy of 3C-SiC on Silicon

In this contribution we investigate the formation at high temperature of an oriented 3C-SiC seed on various orientations of Si substrates “pre-carbonized” through Plasma Immersion Ion Implantation (PIII) process.

Improvement on UHMWPE and PMMA Surface Flashover Under Atmospheric Pressure Using PIII Processing

Polymers are plastic materials used as insulators in power supplies, pulsers, transformers, etc., because of their low cost and excellent insulating properties. However, in several applications, the insulating performance of these materials is limited by the surface flashover instead of the dielectric bulk breakdown (BD). On the other hand, many works have demonstrated that the material hydrophobicity has a huge effect on the increase of resistance to surface flashover in polymers. In this article, to change this material property, the plasma immersion ion implantation (PIII) technique has been used for the treatment of sample surfaces of two important polymers: ultrahigh molecular weight polyethylene (UHMWPE) and poly-methyl-methacrylate (PMMA) used in medical and industrial applications, respectively. By means of the PIII treatment, it was shown that the surface BD voltage of such polymers has increased, improving the resistance to surface flashover. Contact angle diagnostic and atomic force microscopy (AFM) were measured, respectively, for the surface hydrophobicity and roughness to correlate with the increase of the surface BD voltage. Moreover, a special BD testing pulser is employed to assess the polymer resistance to surface flashover by measuring the corresponding BD voltage under atmospheric pressure.

Strain Modification of PECVD Nitride By Plasma Immersion Ion Implantation Processes

Strain engineering was introduced in the microelectronics industry almost two decades ago to improve the carrier mobility due to the modification of the band structures in the Metal Oxide Field Effect Transistor (MOSFET) channel [1, 2]. One method to induce local strain in the transistor channel consists in using Contact Etch Stop Layer (CESL) as stress liner. In order to improve both n-MOS and p-MOS performance, the use of a dual stressed liner (DSL) integration is a solution that combines tensile and compressive films on the same wafer [3]. However, the poor mechanical stability of the compressive PECVD nitride layer when exposed to a high thermal budget, combined with the increased integration complexity, limits the interest of the DSL approach. An alternative solution to tackle these limitations consists in locally transforming the tensile CESL nitride into compressive by Plasma Immersion Ion Implantation (PIII).For this study, PIII processes were performed on 300mm silicon bare wafers capped with a 35nm tensile PECVD nitride. Various species (Hydrogen (H), Helium (He) and Nitrogen (N)) implanted at various acceleration voltages (increasing from 1 to 6 in arbitrary units) and doses (A<B<C) were studied using a Pulsion® tool manufactured by IBS. After these processes, the samples were characterized by various techniques such as ellipsometry, bow measurement, Scanning Electron Microscopy observations, Secondary Ion Mass Spectrometry or FTIR analysis.The stress of the various nitride layers was determined by the Stoney formula, using the curvature measurements and the layer thickness determined by ellipsometry, assuming the shift of the bow results only from the change in nitride stress. Results show that, for all the species studied, the PIII process provides the capability to change the nitride stress from initially tensile to neutral or even compressive when increasing the dose and the acceleration voltage (Fig.1). The largest stress modifications were achieved with nitrogen and hydrogen. For the latter however, the blistering of the nitride layer is observed for the highest doses due to an excessive hydrogen concentration, which is prohibitive for further process integration. By using helium PIII process, the stress change is less for identical process parameters (Fig.1), leading to a neutrally stressed nitride layer. Increasing the helium dose to modify the nitride stress further leads to a consumption of the layer, which limits the use of helium only to the reversal of the mechanical stress.To verify that the stress change will remain during the subsequent process steps, curvature measurements were performed after a consequent thermal budget, equivalent to PMD deposition, applied after the PIII processes. The results show no significant change of the stress level.We demonstrated the capability of PIII processes to turn a tensile CESL nitride layer into a compressive one in a reasonable processing time thanks to the high beam current achievable with PIII process, without any consumption of the layer and without the need of a post implantation thermal treatment. Complementary analysis are on-going to fully characterize the impact of each species on the CESL physicochemical properties and thereby understand its stress evolution. Thanks to these encouraging results, the most promising conditions of all the species mentioned above will be experimented on electrical structures to quantify the related static performance gain.This project (OCEAN12) has received funding from the ECSEL Joint Undertaking (JU) under grant agreement No 783127. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and France, Germany, Austria, Portugal, Greece, Spain, Poland.[1] S. Ito, et al, “Mechanical Stress Effect of Etch-Stop Nitride and its Impact on Deep Submicron Transistor Design”, 2000 IEDM Tech. Dig., p. 247[2] T.K. Kang, IEEE ELECTRON DEVICE LETTERS, VOL. 33, NO. 6, JUNE 2012.[3] H. S. Yang, “Dual Stress Liner for High Performance sub-45nm Gate Length SO1 CMOS Manufacturing”, IEDM 2004 Figure 1

Strain Modification of PECVD Nitride By Plasma Immersion Ion Implantation Processes

The impact of Plasma Immersion Ion Implantation (PIII) processes with various species (hydrogen, helium and nitrogen) on the stress of a tensile PECVD nitride film was evaluated. Ellipsometry measurements indicated no consumption of the nitride but a change in the optical index, signaling a material modification. The initial stress of the nitride was modified by PIII from tensile to mechanically neutral and even compressive. Hydrogen and nitrogen appeared to be more efficient to modify the stress than helium.

Novel Carbon Treatment to Create an Oriented 3C-SiC Seed on Silicon

In this contribution we investigate the possibility to obtain an oriented 3C-SiC seed on Si substrate “pre-carbonized” through Plasma Immersion Ion Implantation (PIII) process by combining PIII with high temperature annealing.

A plasma ion bombardment process enabling reagent-free covalent binding of multiple functional molecules onto magnetic particles

We report a plasma immersion ion implantation process for functionalizing polymer coated magnetic particles, converting them into a universal covalent binding platform for the simultaneous binding of multiple molecular agents without the need for specialised chemical linking groups. As an example, we demonstrate the improvement of wettability and the control of surface charge of polystyrene coated magnetic particles, enhancing biomolecule attachment density with strong covalent binding. We demonstrate the preparation of multifunctional magnetic particles where two or more types of molecule are co-immobilized. This enables a platform technology with simultaneous multiple covalent binding of molecules drawn from oligonucleotides, antibodies and enzymes suitable for targeted nanoparticle diagnostic and therapies.

Optimizing lateral homogeneity of ion-induced surface modifications of non-planar dielectric polyethylene components employing ion fluence simulations and optical measurements of the sp2-dependent reflectivity

Abstract An approach to enhance the durability of artificial joint replacements is to modify the surface of their polymeric bearing material to diamond-like carbon (DLC) by ion-induced polymer-to-DLC-transformation in a plasma-immersion ion implantation process. Due to the dielectric character of the polymer and thus the impossibility of direct application of high voltage pulses to the component, this process requires an additional accelerator electrode above the surface. We here present two useful tools to optimize the geometry of such electrodes. First, we simulate the ions’ trajectories for various electrode geometries and receive the resulting fluence distribution across the surface of the treated part. Second, we introduce a novel optical method to determine non-destructively the local ratio of sp2 hybridized carbon atoms and thus the locally implanted fluence utilizing changes in reflectivity. Combining both tools, we here optimize, by way of example, the geometry of a grid electrode to obtain a homogeneous DLC-modification of a typical hip replacement inlay.

Dynamic determination of secondary electron emission using a calorimetric probe in a plasma immersion ion implantation experiment

A passive thermal probe has been used to detect dynamic changes in the secondary electron emission (SEE). Oxidized and nitrided materials have been studied during argon ion sputtering in a plasma immersion ion implantation process. Identical measurements have been performed for the metallic state with high voltage pulses accelerating nitrogen ions towards the surface, supposedly forming a nitride layer. Energy flux data were combined with scanning electron microscopy images of the surface to obtain information about the actual surface composition as well as trends and changes during the process. Within the measurements, a direct comparison of the SEE within both employed ion species (argon and nitrogen) is possible while an absolute quantification is still open. Additionally, the nominal composition of the investigated oxide and nitride layers does not always correspond to stoichiometric compounds. Nevertheless, the oxides showed a remarkably higher SEE compared to the pure metals, while an indistinct behavior was observed for the nitrides: some higher, some lower than the clean metal surfaces. For the aluminum alloy AlMg3 a complex time dependent evolution was observed with consecutive oxidation/sputtering cycles leading to a very rough surface with a diminished oxide layer, leading to an almost black surface of the metal and non-reproducible changes in the SEE. The presented method is a versatile technique for measuring dynamic changes of the surface for materials commonly used in PVD processes with a time resolution of about 1 min, e.g. magnetron sputtering or HiPIMS, where changes in the target or electrode composition are occurring but cannot be measured directly.

Characterization of SixOyNz coating on CF/PPS composites for space applications

This work deals with the processing and surface treatment of thermoplastic composites carbon fibers/Polyphenylene sulfide (CF/PPS) for aerospace applications. After the production of the thermoplastic composites through hot compression molding, a silicon deposition was carried out on its surface using Plasma Enhanced Chemical Vapor Deposition (PECVD). Then, the Plasma Immersion Ion Implantation (PIII) process was executed on the silicon coated samples to create an amorphous silicon nitride layer. Subsequently, the coated and uncoated samples were characterized by means of the following techniques: optical microscopy, atomic force microscopy (AFM), X-ray diffraction (XRD) and X-ray excited photoelectron spectroscopy (XPS). By analyzing all the results obtained from the characterizations, it was concluded that a layer of amorphous silicon oxynitride was generated on the CF/PPS composite without damaging it. This result is an innovative step concerning the application of this material in a space environment (low earth orbit).

Investigation of microstructure and properties of ultrathin graded ZrNx self-assembled diffusion barrier in deep nano-vias prepared by plasma ion immersion implantation

Ultrathin graded ZrNx self-assembled diffusion barriers with controllable stoichiometry was prepared in Cu/p-SiOC:H interfaces by plasma immersion ion implantation (PIII) with dynamic regulation of implantation fluence. The fundamental relationship between the implantation fluence of N+ and the stoichiometry and thereby the electrical properties of the ZrNx barrier was established. The optimized fluence of a graded ZrN thin film with gradually decreased Zr valence was obtained with the best electrical performance as well. The Cu/p-SiOC:H integration is thermally stable up to 500°C due to the synergistic effect of Cu3Ge and ZrNx layers. Accordingly, the PIII process was verified in a 100-nm-thick Cu dual-damascene interconnect, in which the ZrNx diffusion barrier of 1nm thick was successfully self-assembled on the sidewall without barrier layer on the via bottom. In this case, the via resistance was reduced by approximately 50% in comparison with Ta/TaN barrier. Considering the results in this study, ultrathin ZrNx conformal diffusion barrier can be adopted in the sub–14nm technology node.

Osteogenesis Catalyzed by Titanium-Supported Silver Nanoparticles

Silver nanoparticles (Ag NPs) were widely explored for antimicrobial applications, whereas the translation into drugs and implantable antibacterial devices provoked serious concerns about their potential cytotoxicity. Herein, Ag NPs with diameters ranging from 4 to 19 nm were in situ fabricated and immobilized on titanium by using a plasma immersion ion implantation process. The particles have a population-dependent capability in activating the integrin α5 orchestrated MAPK/ERK signal cascade of osteoblast differentiation in rat bone marrow stem cells (BMSCs), and promoting osteointegration of titanium. It was demonstrated that the titanium-supported Ag NPs played an important role in motivating integrin α5 through triggering the galvanic hydrogen evolution reactions, which was found in positive correlation with the distribution density of the immobilized Ag NPs. Since cellular uptake is a key factor determining the cytotoxic performance of Ag NPs, the extracellular effects of immobilized Ag NPs on promoting osteogenesis provided new insights into the safe application of nanomaterials, and into designing and developing renewed antibacterial devices with selective toxicity.

3-D Numerical Simulation on Plasma Immersion Ion Implantation Batch Treating Process of Bearing Balls

In the plasma immersion ion implantation (PIII) process, since the dose distribution is affected by the sheath around the sample to be treated, controlling the sheath expanding process is very important for obtaining a good dose uniformity. In this paper, a 3-D particle-in-cell (PIC) model was established to study the sheath expanding process around balls of the bearing in a PIII batch treating process respectively. Using the finite difference method, the spatial distributions of the normalized potential and ion density in the simulation region were calculated by solving Poisson’s Equation, Newton’s motion equations and the Boltzmann assumption for the electrons. The influences of the magnitude and pulse width of the implantation voltage applied as well as the plasma density on the sheath conformability were studied. The simulation results show that the sheath conformability around the balls in batch treating process is worse than that in a single process due to the sheath overlap of neighbor bearing components. The bad conformability of the sheath would lead to a bad distribution of the incident dose on the surface of bearing balls. In order to guarantee the conformability of the sheath around the bearing balls, a small pulse width, enough display distance as well as proper implantation voltage and plasma density should be promised in the PIII batch treating process.

Experimental study of mechanical and tribological behavior of nitrogen ion-implanted chromium thin films

Pure chromium coatings can act as decorative or corrosion-resistant coating, but they present poor tribological properties. Even electroplated hard chrome coatings present some problems, as micro-cracks that reduce their corrosion protection and induce fatigue failure. In addition, Cr plating and its dangerous process with Cr VI baths has been banished in several countries. Physical or chemical post-coating treatments can be applied onto coatings in order to enhance their surface properties, as high temperature oxidation, chemical baths or ion implantation. Plasma immersion ion implantation process was carried on PVD chromium coatings as a post-coating treatment and nitrogen ions were implanted on the surface of deposited chromium thin films, by means of two different plasma sources for ion implantation. Both configurations for plasma sources led to the formation of nitride compounds on the surface of the films. The treated films presented low coefficient of friction, high hardness and better adhesion when compared to the untreated film.

Study of the effect of NbN on microwave Niobium cavities for gravitational wave detectors

Superconducting reentrant cavities may be used in parametric transducers for resonant-mass gravitational wave detectors. When coupled to a spherical resonant antenna, transducers will monitor its mechanical quadrupolar modes, working as a mass-spring system. In this paper we will investigate the effect of the Niobium Nitride (NbN), produced through plasma immersion ion implantation (PIII), on the quality factor of reentrant Niobium (Nb) cavities. With the PIII surface treatment unloaded electrical Q-factors (Q0) of the order of 105 were obtained in cryogenic conditions. These results indicated a significant increase in the effect of superconductivity after the cavity surfaces have been heavily attacked by a concentrated acid mixture and after suffering successive PIII processes. Q0's ∼ 3.0 × 105 at 4.2 K are expected to be obtained using Nb RRR399 with a suitable surface treatment. These cavities, with high Q0, are already installed and being tested in the Gravitational Wave Detector Mario Schenberg. The experimental tests have been carried out at the laboratories of the National Institute for Space Research (INPE).

Shallow nitrogen ion implantation: Evolution of chemical state and defect structure in titanium

Evolution of chemical states and defect structure in titanium during low energy nitrogen ion implantation by Plasma Immersion Ion Implantation (PIII) process is studied. The underlying process of chemical state evolution is investigated using secondary ion mass spectrometry and X-ray photoelectron spectroscopy. The implantation induced defect structure evolution as a function of dose is elucidated using variable energy positron annihilation Doppler broadening spectroscopy (PAS) and the results were corroborated with chemical state. Formation of 3 layers of defect state was modeled to fit PAS results.

Schottky barrier dependent antimicrobial efficacy of silver nanoparticles

The antimicrobial efficacy of silver nanoparticles (Ag NPs) modified material was generally governed by the dose of the particles or their capability to release silver ions. Here, it was found that Ag NPs acted against microbes by cooperating with tantalum oxide (TAO) in a Schottky barrier dependent manner. Size tunable Ag NPs were in situ fabricated and immobilized on TAO coating by a silver plasma immersion ion implantation process (Ag PIII). The antibacterial efficacy of these Ag NPs was reversely dependent on their size, that is large particles (~20nm) were more efficiency than small ones (~10nm) in defeating the invasion by bacteria. The result is consistent with the prediction of Schottky-Mott theory, which rectified the electron transfer nature across the interfaces between Ag NPs and the TAO substrate.