Plasma Immersion Ion Implantation System Research Articles

The comparative biological properties of Mg+ or Ca+ implanted Cu–TiN nanocomposite coatings on titanium alloys

In this paper, Cu–TiN nanocomposite coatings on titanium alloys were prepared by multi-target co-sputtering system. On this basis, Mg or Ca ions at the same doses were then implanted into the Cu–TiN coatings respectively via plasma immersion ion implantation system (PIII) to further improve their biological properties. The corrosion resistances, protein adhesion rates, in vitro cell proliferation and bacterial inhibition capabilities of Mg + implanted Cu–TiN and Ca+ implanted Cu–TiN were also compared. The results showed that the Mg+ implanted Cu–TiN showed (i) improved corrosion behavior, (ii) higher protein adsorption capacity, (iii) ideal cell proliferation and adhesion, (iv) better antimicrobial properties. The research results showed that compared with Ca, Mg and Cu–TiN combined better in osteogenetic and antibacterial activities, which could provide a good choice for the surface modification of medical materials.

Co-regulation of Cu/Zn contents enhanced the biological and mechanical properties of TiN coated Ti-6Al-4V alloy

Surface modification is considered to be an important approach for improving the antibacterial activity and cytocompatibility of Ti-6Al-4V alloy. In this study, TiN was firstly deposited on the surface of Ti-6Al-4V alloy by a multi-arc ion plating system to wrap toxic elements and improve the wear resistance. Then Cu and Zn ions with different contents were simultaneously implanted into TiN via plasma immersion ion implantation system (PIII). The chemical characteristics of the samples were investigated by X-ray photoelectron spectroscopy (XPS). The corrosion resistance and hardness of the samples were obtained by potentiodynamic polarization and nanoindenter respectively. The biological assays were evaluated by bovine serum albumin (BSA), MC3T3-E1cells and Escherichia coli (E. coli) in vitro. These results confirm that Cu/Zn-TiN(30 min) has excellent antibacterial property and ideal cytocompatibility, but its mechanical property was slightly inferior to Cu/Zn-TiN(60 min) and Cu/Zn-TiN(90 min). Therefore, the selection of suitable co-implantation content of copper and zinc ions is particularly important for the bone transplants in clinic application.

Enhancement of the mechanical and biological properties on Zn/Ag co-implanted TiN via ions contents regulation

Most orthopedic and dental implants are made of Ti and its alloys due to the excellent biocompatibility and machinability. However, low hardness, biologically inert and poor antibacterial property block its application in the field of hard tissue repair. Therefore, in this study, TiN co-implanted with Zn and Ag (Zn/Ag-TiN) with different contents using the plasma immersion ion implantation system was modified on the surface of titanium alloy to evaluate the mechanical properties, biological properties and antibacterial activities. X-ray photoelectron spectrometer was used to determine the chemical state and composition of samples. The tests of hardness, elastic modulus and scratch of different samples were performed by the nano indenter XP system. Biocompatibility and antibacterial properties were evaluated by MC3T3-E1 cells, bovine serum albumin (BSA) and Escherichia coli (E. coli) in vitro. Results indicate that Zn/Ag(1.5 h)-TiN with the largest content of Zn and Ag exhibits the strongest hardness and adhesion strength, the highest protein adsorption capacity, the best cell adhesion and spreading activity, and ideal proliferation, as well as antibacterial activities, which makes it have great application prospects in orthopedic materials.

Biological actions of Cu/Zn coimplanted TiN on Ti-6Al-4V alloy.

Ti-6Al-4V alloy, as a widely used orthopedic and dental implant, has excellent biocompatibility and machinability. However, its poor corrosion resistance and antibacterial property may lead to tissue inflammation and postoperative infection, which hinders its further development. In this paper, to solve the above problems, copper (Cu) and zinc (Zn) ions were coimplanted into a titanium nitride (TiN) coated Ti-6Al-4V alloy via a plasma immersion ion implantation system (PIII). Then, the structure and composition of Cu/Zn coimplanted TiN (Cu/Zn-TiN-PIII) were characterized by scanning electron microscopy and x-ray photoelectron spectroscopy. Also, the results of the corrosion test, the water contact angles test, and the protein electrophoresis experiment showed that the corrosion resistance, hydrophilicity, and the protein adsorption capacity of Cu/Zn-TiN-PIII were improved simultaneously. In addition, compared with TiN-PIII, Cu/Zn-TiN-PIII promoted both cytocompatibility and the antibacterial property according to L929 cells and Escherichia coli assays in vitro. Therefore, Cu/Zn-TiN-PIII may be a good candidate for orthopedic implants.

Engineering of Shallow Layers of Nitrogen Vacancy Colour Centres in Diamond Using Plasma Immersion Ion Implantation

Sensing nano-scale magnetic field sources is at the heart of many applications in nano-science and biology. Given its very small size and high magnetic sensitivity, the nitrogen vacancy (NV) colour centre in diamond is one of the leading candidates for such applications. However, issues regarding the stability and performance of the NV centre near the diamond’s surface are the major obstacle in the practical realization of theses sensors. So far, conventional implantation and growth techniques did not produce practical and/or repeatable solutions to this problem. In this report, we show first results of shallow layers of NVs created using plasma immersion ion implantation (PIII). We show, using Forster Resonance Energy Transfer (FRET), that most NVs are within 3.6 nm from the diamond’s surface. Despite the relatively low quality of the diamond substrates used and the simplicity of our PIII system, we have an estimated magnetic sensitivity of around 2.29 μT/sqrt{Hzcdot mu {m}^{-2}}.

Recent experiments on plasma immersion ion implantation (and deposition) using discharges inside metal tubes

Plasma immersion ion implantation (PIII) of nitrogen inside metallic tubes of different diameters and configurations were attempted recently. PIII tests in practical size metallic tubes of SS304, ranging from 1.1 to 16 cm∅ and length of 20 cm, were carried out as a continued effort in our lab, to explore PIII inside tubes. Tubes in laying down positions and configurations including metallic lid in one side or both sides open were used, as well as, plane sample support placed 10 cm far from the tube mouth and without bias, taking advantage of plasma flowing out the tube. In particular, nitrogen and argon PIIIs were tested for tube inner wall sputtering and deposition studies, running the PIII system in the last configuration of sample support detached from the tube. During the nitrogen ion implantation runs in other cases, it was found that the final temperature of the tubes and the plasma turn-on voltages were both inversely proportional to the dimensions of the tubes, except for the smallest tube tested. High voltage glow and hollow cathode discharges were produced inside the tubes, either alternately, during the pulse or independently, depending on the tube geometry and pulser used (LIITS, a current controlled source or RUP-4, a voltage controlled one). In the case of smallest diameter of 1.1 cm∅, a suspended tube of SS304 was tested using lower power pulser (RUP-4), at its near maximum capability of 1.2 kW. In this case also, very bright plasmas were formed, mainly inside the tube and resulted in high temperature there (~700 °C). Nitrogen uptake was superior for higher temperature PIII treatments (>700 °C), combining ion implantation and thermal diffusion, which allowed the formation of TiN and Ti2N on the Ti alloy samples inside tubes with diameters ≤4 cm. In this paper, detailed discussion of results of above cited PIII tests with diversified tubes and configurations are presented, together with the analysis of the corresponding treated surfaces of the samples inside, outside and on the support detached from the tube.

Irradiation influence on Mylar and Makrofol induced by argon ions in a plasma immersion ion implantation system

Mylar and Makrofol polycarbonate polymers were irradiated by Ar ions in a plasma immersion ion implantation (PIII) system. The surface wettability of both polymers was investigated by employing the contact angle method. The measured contact angles were found to depend on the surface layer properties. Good wetting surfaces were found to depend not only on surface roughness but also on its chemistry that analyzed by Fourier transform infrared (FTIR) spectroscopy. Surfaces topography and roughness was investigated and correlated to their surface energy which studied with the aid of acid-base model for evaluating the improvement of surface wettability after irradiation. PIII improves polymers surface properties efficiently in a controllable way.

Characterization of the AISI 304 Alloy Treated in a Large Vacuum Chamber PIII System with a New HV Pulser

Plasma immersion ion implantation (PIII) method is often used to cleaning and enhancing mechanical properties of the surface of materials. In this work, the AISI 304 was treated in a PIII system to improve tribological and wear resistance properties. The new HV pulser was prepared to reach high average power (10 kW) using solid-state technology and a pulse transformer rather than using a conventional one based on hard-tube tetrodes with HV storage capacitors. For preliminary tests, low-density nitrogen plasma and pulses of 10 kV, 30μs width, and 1 kHz were used. A larger vacuum chamber used (600 liters) is very important for treating large area components and for batch processing. This is necessary in industrial applications and in cases that require high quality processing as in spatial or medical components. Stainless steel support was used to hold the samples in our case. XRD, SEM, and pin-on-disk surface diagnostics were used for investigation and characterization of the treated surfaces.

A new high-temperature plasma immersion ion implantation system with electron heating

Abstract The temperature of the substrate has strong influence on the diffusion coefficient of nitrogen ions during plasma immersion ion implantation (PIII) performed in metallic surfaces, which affect the ion implantation profiles and can lead to the formation of thick implanted layers. In order to heat conveniently a large spectrum of metals and metallic alloys in vacuum and in the presence of plasma, as mandatory for efficient PIII, it is necessary to count on a stable heat source, able to provide steady temperatures in the range of 200 °C to more than 1000 °C. This has been accomplished in the current experiment by means of a thermionic cathode composed of a rolled tantalum foil covered with (Ba,Sr,Ca)O. Work-function of this electron source is around 2.1 eV, which is much lower than 4.5 eV of typically used tungsten filament. Metallic samples studied, in this case, are the anode of the discharge itself, being polarized during the heating cycle by positive DC voltages in the 100–800 V range. They are implanted with negative pulses up to 10 kV/300 Hz/40 µs.

Numerical Simulation of Magnetic-Field-Enhanced Plasma Immersion Ion Implantation in Cylindrical Geometry

Recent studies have demonstrated that the sheath dynamics in plasma immersion ion implantation (PIII) is significantly affected by an external magnetic field. In this paper, a two-dimensional computer simulation of a magnetic-field-enhanced PIII system is described. Negative bias voltage is applied to a cylindrical target located on the axis of a grounded vacuum chamber filled with uniform molecular nitrogen plasma. A static magnetic field is created by a small coil installed inside the target holder. The vacuum chamber is filled with background nitrogen gas to form a plasma in which collisions of electrons and neutrals are simulated by the Monte Carlo algorithm. It is found that a high-density plasma is formed around the target due to the intense background gas ionization by the magnetized electrons drifting in the crossed EtimesB fields. The effect of the magnetic field intensity, the target bias, and the gas pressure on the sheath dynamics and implantation current of the PIII system is investigated

Fabrication of diamond-like amorphous carbon cantilever resonators

Amorphous carbon (a-C) films were deposited by an off-plane double bend filtered cathodic vacuum arc technique fitted with a plasma immersion ion implantation system. High resolution XPS measurements showed these films have an sp3 content of about 60%. Laser-surface acoustic wave measurements have shown such films to have a Young’s modulus and density of 310GPa and 2.33g∕cm3. 1.2μm thick a-C films were grown and subsequently patterned into 150μm×50μm cantilevers using standard photolithography. Residual stress measurements were obtained from the curvature of bend of the cantilever. An accurate knowledge of the microstructural properties will in turn give accurate modeling results. Simulation results showed that such free-standing cantilevers fabricated with amorphous carbon films have resonant frequency much higher than standard polysilicon cantilevers. As such, free-standing diamond-like amorphous carbon cantilevers had been fabricated. The resonant frequency of these cantilevers was measured by laser vibrometer to be ∼108MHz, in very good agreement with simulation results.

Surface modification of polyethylene terephthalate by plasma immersion ion implantation

Plasma immersion ion implantation (PIII) of nitrogen has been successfully employed to form an amorphous carbon layer on the surface of 0.25-mm-thick polyethylene terephthalate (PET) sheet used for manufacturing plastic bottles. A DC glow discharge source with controlled floating plasma potential was used to create nitrogen plasma in a 100-l PIII system. The polymer specimens were pulsed (through a metallic grid or sample holder) at repetition rate of 300 Hz with high negative voltage pulse of 10 kV magnitude and 80 μs duration. Formation of carbon film on the PET surface as a result of nitrogen ion implantation was investigated using Raman spectroscopy, optical and atomic force microscopy (AFM). The obtained Raman spectra reveal that the amorphous carbon layer has diamond-like characteristics. AFM micrographs demonstrate that after PIII treatment, the PET surface became much smoother and no cracks were found on it.

High temperature nitrogen plasma immersion ion implantation into molybdenum

High dose, high temperature nitrogen implantation into molybdenum was realised in a plasma immersion ion implantation system with additional heating in the temperature range between 500 and 750 °C. X-ray diffraction spectra show the transformation of c-Mo 2N into t-Mo 2N near 580 °C. At the same temperature, the thermally activated growth of the layer thickness by diffusion from the surface became noticeable. A variation of the pulse voltage between 5 and 30 kV did not change the nitrogen surface concentration in sputter saturation.

Doping concentration evaluation using plasma propagation models in plasma immersion ion implantation (PIII) system

Plasma immersion ion implantation (PIII) is a high dose-rate implantation process technique in the area of semiconductor device fabrication used to fabricate various device structures like shallow junction, silicon on insulators and in the processing of flat panel display materials, trench doping, etc. The basic mechanism of ions source and their acceleration in PIII technique is different from that of the conventional ion-implantation. In this, the target is immersed in a plasma source and the implantation is done by accelerating the ions with a negative pulse bias voltage, applied to the target. The dynamics of ion transport and the implantation is different from line-of-sight implantation. In this paper, the doping of individual ions (Ar, He and N), in a collisionless PIII system is studied analytically when a negative pulse of 10 kV is applied to the target. The net ion doping concentration in one pulse duration has also been computed during the propagation of plasma sheaths.

Surface improvements of industrial components treated by plasma immersion ion implantation (PIII): results and prospects

The major drive for PIII research in recent years has been the widespread use of plasma-based ion implantation in industries aiming at attaining high value-added components. After achieving the domain of the complete basic PIII cycle, we started to pursue the implementation of this process in various types of industrial components. A DC glow discharge source with a controlled plasma floating potential was used in a 100-l PIII system driven by a 30-kV peak voltage, 50 μs duration, up to 1.1 kHz pulse power source, in order to process the components which were provided by regional companies, spanning from machinery tools to prosthesis. The industrial components were set-up in the PIII chamber as received from the companies, after a simple cleaning procedure. In this phase, only nitrogen implantation was performed. The required processing times were typically from 60 to 120 min and the components were treated either individually or in batches. Fast steel drill bits, knife blades for wood cutting, tools for odontological applications, molds made of fast steel, a prosthesis made of Ti alloy, etc., have been three-dimensionally implanted successfully. Next, improvements in the PIII ongoing system included: a 10-kW pulser with up to 60 kV capability, turbo-pump, refrigerated walls, auxiliary heating of the components, a larger chamber and a magnetron sputtering source for hybrid treatments.

A plasma immersion implantation system for materials modification

A plasma immersion ion implantation (PIII) system is described which provides the capability to bridge the range between research exploration and commercial applications for materials modification of electronic materials, with a particular focus on layer transfer processes. The Silicon Genesis PIII system is capable of operation at high plasma densities (≈5×10 11 ions/cm 3 at the wafer) with high purity, mono-species ionization (>99% H + ions with a hydrogen plasma). The first generation of Silicon Genesis PIII systems is equipped to use 200-mm wafers (through an automated loadlock) and pulsed potentials up to 50 kV. Use of the mono-species ionization characteristic of the Silicon Genesis PIII system provides the capability to precisely vary the characteristics of surface layers through implantation of atoms and damage creation at well-controlled depths in the materials of choice. The Silicon Genesis PIII system is designed for efficient production of SOI and other layer transfer-generated materials and can be adapted for materials modification of more complex structures and work pieces.

Direct current plasma implantation using a grounded conducting grid

A novel plasma implantation technique performed in a low pressure steady state dc mode utilizing a grounded conducting grid on top of the wafer stage is presented. By numerically simulating the ion paths by the particle-in-cell method, it is observed that the ion paths are optimized for certain implant geometry. In the optimal configuration, the directional angle of the acceleration vector does not depend on the mass and charge state of the ions, and the ratio of the partial differential of the scalar potential φ along the radial and longitudinal directions remains constant for varying applied voltages. The retained dose and impact energy uniformity are totally determined by the ratio of the radius of the wafer stage r, radius of the vacuum chamber R, distance between the wafer stage and the grid H, and thickness of the wafer stage D. The optimal ratio is r:R:H:D=1:4:2.5:2, that is, suggesting a disk shape vacuum chamber, which is quite different from that of a conventional plasma immersion ion implanter. In addition to retaining the large area and parallel processing advantages of plasma immersion ion implantation (PIII), the implantation energy can be extended far beyond the limit of PIII as the technique obviates the use of the power modulator, which not only limits the implantation energy but also is the most expensive and technologically complex hardware component in a PIII system.

Production of stable and metastable phases of zirconium nitrides by NH3 plasma nitridation and by double ion beam sputtering of zirconium films

Nitrided surfaces and nitrogen composition gradients in thin films exhibit interesting mechanical, electrical and optical properties. Metal, semiconductor or oxide surfaces can be transformed into a nitrided compound via interactions of nitrogen species issued from a plasma or an ion beam. The thermal activation is a key factor in both cases to ensure chemical reactions and short/long-range diffusion necessary to allow the growth of stable or metastable structures. In this work, we focus our attention on zirconium nitrides prepared under controlled temperature through reaction and diffusion, in Zr films, of low energy NHx species produced in NH3 plasma and through the implantation–diffusion of energetic N+2 ions during Zr deposition by using double ion beam sputtering. Zirconium nitrides show optical and electrical properties that depend on the conditions and on kinetics of the nitrogen take-up; the material exhibits a transition from the stable metallic ZrN to a metastable phase Zr3N4 that appears transparent and insulating. The influence of the energy of the nitriding species and of the temperature on nitride compositions and phases are addressed. A model using coupled implantation and thermal diffusion mechanisms is proposed to explain the phases produced. In relation with the described phenomena, a temperature-controlled plasma-immersion ion-implantation system is proposed for tailoring in-depth stable/metastable ceramic structures such as nitrides, oxides and carbides.

Plasma immersion ion implantation. A new method for homogeneous surface modification of complex forms of medical implants

Plasma immersion ion implantation (PIII) is a new method for the inexpensive rapid modification of the near-surface region of medical implants of complex shapes. PIII combines the advantages of conventional plasma and ion beam technologies. This article describes the physical basis of the procedure and the construction of a PIII system, and presents typical PIII parameters. In a number of examples, the use of the PIII to modify the surface of biocompatible materials (chrome-nickel stainless steel, titanium, titanium-aluminium-vanadium alloy) with the aim of reducing wear, increasing biocompatibility or improving adhesion, is described. Finally, the possibilities of combining PIII with other technologies are considered.

Active and passive plasma spectroscopy in a plasma immersion ion implantation (PIII) experiment

Plasma immersion ion implantation (PIII ) is an emerging surface modification technique that can be used for three-dimensional ion implantation of non-planar components at low cost compared with the traditional line-of-sight implantation method using accelerators. We have developed a PIII system based on 2.45 GHz microwave-generated plasmas with densities of 1016‐1017 m’3 and temperatures of few eV which allow high-ion-flux implantation in components of complex shape. These plasma parameters are also adequate for diagnostics using passive and active spectroscopic methods even in the presence of high voltages applied to the samples. The principles of active plasma spectroscopy (beam emission spectroscopy) for microwave PIII plasmas and its present status in our laboratory, as well as preliminary passive spectroscopy results, are described. Furthermore, results on the characterization of some irradiated samples and optimization of our PIII device are also presented. © 1999 Elsevier Science S.A. All rights reserved.