Hydrogen Plasma Immersion Ion Implantation Research Articles

Hydrogen plasma treated-Ce-BTC nanorods enable enhanced antibacterial activity and soft tissue sealing ability

Implant-associated infections caused by the formation of bacterial biofilms on the implant surface are difficult to cure, which will lead to poor integration between soft tissues and percutaneous implants. To solve this issue, in this work, cerium-based metal-organic framework (Ce-BTC) coatings with abundant coordinative unsaturated metal sites were fabricated on medical titanium surfaces by solvothermal treatment and followed by hydrogen plasma immersion ion implantation (H-PIII) treatment. The surface microstructure of Ce-BTC had no obvious changes after H-PIII treatment, while the crystallinity reduced and the organic ligands were partially etched, resulting in more metal active sites being exposed. Consequently, adenosine triphosphate (ATP) deprivation capacity and oxidase-like activity of Ce-BTC were significantly improved by H-PIII treatment, which could effectively prevent biofilm formation and kill bacteria in response to the bacteria-mediated acidic microenvironment. Moreover, the Ce-BTC treated by H-PIII for 15 min could promote the fibroblast responses including cell proliferation and collagen deposition by up-regulating fibroblast-related genes in vitro, which may be ascribed to the surface nanorod structures and the released Ce ions. The percutaneous infection model in vivo further confirmed that the Ce-BTC treated by H-PIII for 15 min had good antibacterial activity and soft tissue sealing ability, which was conducive to the integration between percutaneous implants and surrounding soft tissues.

Enhanced adhesion strength and solid lubricity of graphite like amorphous carbon films by hydrogen implantation

Hydrogen-free graphite-like carbon (GLC) films with columnar nanostructure were modified by hydrogen plasma immersion ion implantation (PIII) at a relatively high pulse voltage of 30 kV. The transition from a columnar nanostructure to a glassy structure in the top layer of the implanted films was firstly observed by transmission electron microscopy . Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was employed to survey the depth profile information of hydrogen (H) and carbon‑hydrogen (C H) bonds, and the results showed that the implanted hydrogen intensively distributed in the glassy layer. The results of Raman spectra showed that disorder of carbon bonds increased and a diamond like carbon structure was derived near the films surface through hydrogen ions implantation. The adhesion strength and tribological performance in nitrogen of GLC were enhanced significantly by hydrogen implantation. • Nano-columnar transferred into glassy structure in hydrogen implanted GLC films. • A hydrogen-rich layer induced by hydrogen implantation. • Adhesion strength enhanced by the hydrogen implantation. • Ultralow stable friction of GLC films in dry nitrogen realized through hydrogen implantation.

Study of silicon surface layers modified by hydrogen plasma immersion ion implantation and oxidation

We report a study of p-Si(100) surface layers modified by plasma immersion ion implantation (PIII) and dry oxidation. This is expected to allow one to engineer near-surface layers with different thicknesses and levels of amorphization. Hydrogen ions were introduced into a shallow near-surface Si region through PIII with energy of 2 keV and doses ranging from 1013 ion/cm2 to 1015 ion/cm2. The implanted Si surface was subjected to oxidation in dry oxygen atmosphere at temperatures ranging from 700 °C to 800 °C. The optical and structural properties of the modified Si layers were studied in detail by spectroscopic ellipsometry (SE) in the IR spectral range of 300 – 4000 cm−1. The surface morphology was examined by atomic force microscopy (AFM) imaging at different scales and by fractal analysis. Through decomposition of the main Si-O bands into Gaussian peaks, different Si oxidation states were identified, suggesting non-stoichiometric oxide layer composition.

Enhanced osteogenic activity and bacteriostatic effect of TiO2 coatings via hydrogen ion implantation

Titanium implants fabricated by micro-arc oxidation (MAO) are widely used in orthopedic therapies. However, TiO2 is a bio-inert material and lacks antibacterial properties. Therefore, it is crucial to enhance the biological activity and antibacterial properties of MAO implants. In this work, TiO2 coatings were fabricated by MAO and further hydrogen plasma immersion ion implantation (H-PIII). The formation of Ti-OH bonds promoted cell proliferation and osteogenic differentiation. The presence of Ti3+ and oxygen vacancies narrowed the forbidden band of TiO2 and showed bacteriostatic effect to E. coli and S. aureus.

Physical and chemical effects of the hydrogen irradiation on nitrided titanium surfaces

Many applications aiming the use of titanium and titanium-based materials involve the surface interaction with protons or hydrogen isotopes, such as in chemical and nuclear power plants, marine and aerospace environments. Because of the high affinity of titanium for hydrogen and the consequent deleterious effects, the study of surface interactions contributes to the understanding of the protection mechanisms, such as the H-diffusion barrier provided by nitriding, as well as the fine surface tailoring achieved by hydrogenation. Nitrided titanium surfaces were produced via plasma nitriding (PN), carried out at 400°C and 600°C. Afterwards, titanium and nitrided titanium were submitted to the hydrogen plasma immersion ion implantation (H-PIII), using ion energies from 1.2 to 5.0keV. The hydrogen modifications imposed were restricted to the nanometer depth range, causing no significant variations in hardness and elastic modulus (measured in depths larger than 70nm) or in the crystalline structure, as inferred from nanoindentantion and grazing incidence X-ray diffraction, respectively. From the X-ray photoelectron and micro-Raman spectroscopies, the hydrogen irradiation was found to cause denitriding on the nitrided titanium, changing the TiN stoichiometry as a consequence of conjoined physical and chemical effects on the surface atoms. The atomic N/Ti ratio changed from 0.9 (not hydrogenated) to 0.6 (5keV) up to ~2nm depth. The Ti/N decrement and the resulting TiO2 surface layer growth followed approximately linear correlations with the implantation energies. Additional investigations with Fourier-transform infrared spectroscopy disclosed vibrational bands featured by a strong line at 668cm−1 (possibly OTi(OH)2) in samples submitted independently to PN and H-PIII, suggesting that different mechanisms of hydroxyl absorption on titanium took place on those surfaces.

High-Performance Multilevel Resistive Switching Gadolinium Oxide Memristors With Hydrogen Plasma Immersion Ion Implantation Treatment

Multilevel resistive switching (RS) of gadolinium oxide (Gd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> ) memristors treated by hydrogen plasma immersion ion implantation (PIII) was investigated. Hydrogen ions were implanted at the Pt/Gd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> interface to modify the oxygen-vacancy distribution, which was examined by the X-ray photoelectron spectroscopy. After the hydrogen PIII treatment, a forming process is needed to operate the Gd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> memristors and the RS mechanism is changed from Schottky emission to space-charge-limited conduction. Superior multilevel RS properties such as data retention for more than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> s at 85°C, and sequentially cycling test for more than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> times with a resistance ratio of approximately one order of magnitude between each state are realized, making the future high-density flash memory possible.

Performance improvement of gadolinium oxide resistive random access memory treated by hydrogen plasma immersion ion implantation

Characteristics improvement of gadolinium oxide (GdxOy) resistive random access memories (RRAMs) treated by hydrogen plasma immersion ion implantation (PIII) was investigated. With the hydrogen PIII treatment, the GdxOy RRAMs exhibited low set/reset voltages and a high resistance ratio, which were attributed to the enhanced movement of oxygen ions within the GdxOy films and the increased Schottky barrier height at Pt/GdxOy interface, respectively. The resistive switching mechanism of GdxOy RRAMs was dominated by Schottky emission, as proved by the area dependence of the resistance in the low resistance state. After the hydrogen PIII treatment, a retention time of more than 104 s was achieved at an elevated measurement temperature. In addition, a stable cycling endurance with the resistance ratio of more than three orders of magnitude of the GdxOy RRAMs can be obtained.

Hydrogen plasma surface activation of silicon for biomedical applications

Silicon has gradually been recognized to be an essential trace element in the normal metabolism of higher animals, and the role of silicon in the human body has aroused interests in the biomedical community. In fact, the interactions between silicon-based devices and the human body such as biosensors and microelectromechanical systems (MEMS) often suffer from poor biocompatibility. In this work, hydrogen plasma immersion ion implantation (H-PIII) is conducted to improve the bioactivity or bone conductivity of silicon. In order to investigate the formation mechanism of bone-like apatite on the surface of the hydrogen implanted silicon wafer, two comparative experiments, hydrogenation and argon bombardment, are performed. The H-PIII sample exhibits an amorphous surface consisting of Si–H bonds. After immersion in simulated body fluids, a negatively charged surface containing the functional group ( Si–O −) is produced and bone-like apatite is observed to nucleate and grow on the surface. The surface of the H-PIII silicon wafer favors the adhesion and growth of osteoblast cells and good cytocompatibility may be inferred.

Hydrogen plasma immersion ion implantation of ultra‐high molecular weight polyethylene

AbstractUltra‐high molecular weight polyethylene (UHMWPE) was treated by hydrogen plasma immersion ion implantation (PIII). Accelerating voltages (U) between 15 and 30 kV, fluences (F) between 1 × 1017 and 3 × 1017 cm−2 with fluence rates (FR) between 3 × 1013 and 7 × 1013 cm−2 s−1 were applied. The surface chemical characterisation was performed by XPS. Nanomechanical properties like hardness (H), reduced modulus (E) and slope of scratch (S) of the untreated and modified surfaces were characterised by nanoindentation and nanoscratch measurements.The results demonstrate that hydrogen PIII‐treatment can significantly and favourably modify the nanomechanical properties of UHMWPE. The dependence of these properties on the main process parameters has been determined. Copyright © 2006 John Wiley &amp; Sons, Ltd.

The role of grain boundaries in the mechanism of plasma immersion hydrogenation of nanocrystalline magnesium films

Abstract In this paper, attention in focused on the nanostructured magnesium films for hydrogen storage. It is shown that 2 μm thick Mg film is transformed into MgH2 film under high-flux and fluence hydrogen plasma immersion ion implantation at 450 K for 15 min. All hydrogen desorbs at temperature about 530 K, which corresponds to the decomposition of MgH2 → Mg + H2↑. The macroscopic and microscopic observations show that magnesium film undergoes a high deformation and restructuring during hydrogenation–dehydrogenation reaction. The suggested hydrogenation model is based upon the incorporation of excess of hydrogen atoms in grain boundaries of nanocrystalline Mg film driven by the increase in surface chemical potential associated with the implantation flux. The results provide new aspects of hydriding of thin nanocrystalline film materials under highly non-equalibrium conditions on the surface.

Plasma-treated nanostructured TiO 2 surface supporting biomimetic growth of apatite

Although some types of TiO 2 powders and gel-derived films can exhibit bioactivity, plasma-sprayed TiO 2 coatings are always bioinert, thereby hampering wider applications in bone implants. We have successfully produced a bioactive nanostructured TiO 2 surface with grain size smaller than 50 nm using nanoparticle plasma spraying followed by hydrogen plasma immersion ion implantation (PIII). The hydrogen PIII nano-TiO 2 coating can induce bone-like apatite formation on its surface after immersion in a simulated body fluid. In contrast, apatite cannot form on either the as-sprayed TiO 2 surfaces (both <50 nm grain size and >50 nm grain size) or hydrogen-implanted TiO 2 with grain size larger than 50 nm. Hence, both a hydrogenated surface that gives rise to negatively charged functional groups on the surface and small grain size (<50 nm) that enhances surface adsorption are crucial to the growth of apatite. Introduction of surface bioactivity to plasma-sprayed TiO 2 coatings, which are generally recognized to have excellent biocompatibility and corrosion resistance as well as high bonding to titanium alloys, makes them more superior than many current biomedical coatings.

Synthesis of Mg(AlH 4) 2 in bilayer Mg/Al thin films under plasma immersion hydrogen ion implantation and thermal desorption processes

The behavior of hydrogen in Mg/Al bilayer films introduced by 1 kV pulsed hydrogen plasma immersion ion implantation has been studied. The changes in structure and composition of hydrogenated films were analyzed by glow discharge optical emission spectroscopy, X-ray diffraction (XRD) technique and scanning electron microscope (SEM). The XRD studies show that samples implanted to saturation at temperature below 370 K exhibit nanocrystalline magnesium alanate, Mg(AlH 4) 2, which is potential hydrogen storage material. The hydrogenated films demonstrate homogeneous distribution of matrix elements and hydrogen across their thickness. The thin 3–5 nm thick layer of the natural Al 2O 3 oxide protects magnesium alanate from the direct contact with air. The correlation between the effusion of implanted hydrogen and the evolution of surface morphology was studied by the thermal desorption plasma spectroscopy and SEM. In 400–600 K temperature region there is only a weak effusion of hydrogen because the surface oxide layer is not permeable. SEM analysis reveals bubbles at a temperature of 500 K and the increase of their number density and size up to a temperature of ∼575 K. The major part of hydrogen effuses at ∼640 K. The effusion process has an activation energy of 1.85 ± 0.05 eV which is very close to the activation energy for hydrogen diffusion in γ-Al 2O 3.

Improvement of surface bioactivity on titanium by water and hydrogen plasma immersion ion implantation

We have investigated the surface bioactivity of titanium after water and hydrogen plasma immersion ion implantation. Plasma immersion ion implantation (PIII) excels in the surface treatment of components possessing a complicated shape such as medical implants. In addition, water and hydrogen PIII has been extensively studied as a method to fabricate silicon-on-insulator (SOI) substrates in the semiconductor industry and so it is relatively straightforward to transfer the technology to the biomedical field. In our investigation, water and hydrogen were plasma-implanted into titanium sequentially. Our objective is that water PIII introduces near-surface damages that trap hydrogen implanted in the subsequent step to improve the surface bioactivity while the desirable bulk properties of the materials are not compromised. Ti–OH functional groups can be detected on the (H 2O+H 2)-implanted titanium surface by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. After incubation in simulated body fluids (SBF) for cytocompatibililty evaluation in vitro, bone-like hydroxyapatite was found to precipitate on the (H 2O+H 2) implanted samples while no apatite was found on titanium samples plasma implanted with water or hydrogen alone. Human osteoblast cells were cultured on the (H 2O+H 2)-implanted titanium surface and they exhibited good adhesion and growth. Our results suggest a practical means to improve the surface bioactivity and cytocompatibility of medical implants made of titanium.

Highly thermal robust NiSi for nanoscale MOSFETs utilizing a novel hydrogen plasma immersion ion implantation and Ni-Co-TiN tri-layer

In this letter, hydrogen plasma immersion ion implantation (H PIII) with Ni-Co-TiN tri-layer is introduced for the first time to enhance the thermal stability of the Ni-silicide for nanoscale CMOS technology. The Ni-silicided poly-Si gate and source/drain showed stable sheet resistance in spite of 650/spl deg/C, 30 min post-silicidation annealing. The junction leakage current is even improved a lot without degradation of device performance using the proposed method.

Semiconductor applications of plasma immersion ion implantation

Plasma immersion ion implantation (PIII) is an established technique in certain niche microelectronics applications such as the synthesis of silicon-on-insulator. In other applications such as shallow junction formation by plasma doping, trench doping, and fabrication of blue light emitting materials, PIII has unique advantages over conventional techniques and may be the technique of choice in the future. There have been significant developments in these areas and recent breakthroughs in plasma and trench doping are discussed in this review paper. Results pertaining to direct-current PIII that excels in planar sample processing as well as the optical characteristics of nano-cavities produced by hydrogen PIII are also presented.

Contamination issues in hydrogen plasma immersion ion implantation of silicon—a brief review

Hydrogen plasma-immersion ion implantation (PIII) is an effective technique to fabricate silicon-on-insulator (SOI) and conduct microcavity engineering. Unlike metallurgical applications, the introduction of a trace amount of contaminants, such as transition metals, into the silicon wafers can seriously compromise the product yield and device performance. In PIII experiments, ions bombard all surfaces inside the PIII vacuum chamber, especially the negatively pulsed biased sample stage and to a lesser extent the interior of the vacuum chamber. Consequently, impurities are sputtered from these exposed surfaces and can be re-implanted into or absorb onto the semiconductor wafers. In hydrogen PIII, which is the first step in the PIII/ion-cut process to synthesize SOI wafers, the need for sample cooling makes the design and construction of an all-silicon sample chuck technically difficult. In this review, recent theoretical and experimental work conducted on identifying the sources of metallic contamination, quantifying the extent of contamination, as well as means to mitigate atmospheric and metallic contamination is reviewed. The results suggest that the use of an all-silicon liner and silicon guard-ring dramatically allays the severity of metallic contamination. However, the use of single-crystal silicon as the guard-ring or coating material is not preferred, because the materials blister after hydrogen implantation and particles are released into the vacuum chamber. Three silicon-compatible materials are proposed, and experimental results indicate that a thin silicon oxide coating has the highest immunity to hydrogen-induced surface blistering, while having a minimal affect on the surrounding electric field.

Hydrogen-induced surface blistering of sample chuck materials in hydrogen plasma immersion ion implantation

Hydrogen plasma immersion ion implantation (PIII) coupled with ion cut is an economical way to synthesize silicon-on-insulator wafers. In order to avoid premature surface blistering caused by the coalescence of hydrogen microcavities, the implantation temperature must be low (&amp;lt;300 °C), and sample cooling is usually required due to the high ion flux in hydrogen PIII. In addition, the entire sample chuck including the silicon wafer and all the exposed surfaces are bombarded by ions and sputtered impurities from the sample holder can be reimplanted or deposited onto the silicon wafer. Ideally, the problem can be solved if the sample chuck is made of silicon but engineering a silicon sample chuck with sufficient electrical conductivity and a cooling mechanism is very complicated. In addition, the hydrogen ions implanted into the exposed silicon chuck surface can cause surface blistering and exfoliation similar to the silicon wafer. The silicon particles released into the vacuum chamber will reduce the process yield. One practical approach is to engineer the sample chuck with stainless steel and then coat the surface with a material compatible with silicon. If the blistering resistance of the coating is better and the lifetime of the coating is sufficiently long, periodic cleaning can ensure particle and contamination free operation. In this work, we investigate the blistering behavior of three such materials, single-crystal silicon, polycrystalline/amorphous silicon, and silicon dioxide. Our results show that silicon dioxide is the best candidate, followed by polysilicon. However, the insulating nature of silicon dioxide must be considered. Our theoretical simulation results show that an oxide layer several micrometers thick will not affect the surface potential significantly even at a relatively low bias voltage.

Damage in hydrogen plasma implanted silicon

The damage and defects created in silicon by hydrogen plasma immersion ion implantation (PIII) are not the same as those generated by conventional beamline ion implantation due to the difference in the ion energy distribution and lack of mass selection in PIII. Defect generation must be well controlled because damage in the implanted and surface zones can easily translate into defects in the silicon-on-insulator structures synthesized by the PIII/wafer bonding/ion-cut process. The defect formation and its change with annealing temperature were investigated experimentally employing channeling Rutherford backscattering spectrometry, secondary ion mass spectrometry, and atomic-force microscopy. We also calculated the damage energy density of the three dominant hydrogen species in the plasma (H+, H2+, and H3+) as well as displacement of silicon atoms in the silicon wafer. H2+ creates the most damage because its damage energy density is very close to the silicon threshold energy. The effects of atmospheric gaseous impurities unavoidably coimplanted from the overlying plasma are also modeled. Even though their concentration is usually small in the plasma, our results indicate that these gaseous impurities lead to significant silicon atom displacement and severe damage in the implanted materials.

Steady-state direct-current plasma immersion ion implantation using a multipolar magnetic field electron cyclotron resonance plasma source

In semiconductor plasma immersion ion implantation (PIII) applications such as the synthesis of silicon-on-insulator by hydrogen PIII and ion cut, only ions arriving at the top surface of the sample stage are important. The ions implanted into the other surfaces of the sample chuck actually not only decrease the efficiency of the power supply and plasma source but also give rise to metallic contamination. In addition, low energy ions introduced by the initial plasma sheath propagation, pulse rise time, and pulse fall time introduce a large surface hydrogen concentration that creates surface damage and affects the wafer bonding efficacy. We have theoretically demonstrated direct-current PIII (DC-PIII) which retains the x–y immersion characteristic while simultaneously reducing this low energy ion component, obviating the need for the expensive power modulator, and extending the voltage ceiling that is no longer limited by the vacuum chamber and power modulator. In this article, we describe our hydrogen DC-PIII experiments using a conducting grid placed between the wafer stage and a multipolar electron cyclotron resonance plasma source. The grounded grid stops the propagation of the plasma sheath, thereby removing the vacuum chamber size limitation. Ions are formed in the plasma sustained by an external plasma source above the grid and accelerated through the lower zone to be implanted into the wafer biased by only a dc power supply. Atomic force microscopy, hydrogen forward scattering, and secondary ion mass spectrometry analyses indicate uniform hydrogen PIII into a 100 mm silicon wafer and the surface hydrogen component is indeed reduced significantly compared to conventional pulsed PIII.

Applications of plasma immersion ion implantation in microelectronics — a brief review

Recent advances in plasma immersion ion implantation (PIII) are progressing at a rapid pace. PIII was originally envisioned as a conformal ion implantation technology for the surface modification of materials. PIII also offers the advantages of high dose rates, even at low energy, and single wafer implants over large areas. Such advantages are becoming very important for semiconductor manufacturing, particularly for 300-mm wafers and flat panel displays. Applications of PIII in microelectronics introduce new considerations. Conformal implantation is not required, and is unwanted in most semiconductor processes, except for trench doping-type applications. In various implant applications, there are often radically different requirements of plasma physics and chemistry. For example, the formation of shallow junctions requires extremely low energy implantation, and a precise implant range may not be necessary or ideal. In this application, PIII becomes the concept of plasma doping, where a wafer under either a DC or pulse bias is directly exposed to the plasma. On the other hand, hydrogen PIII for layer transfer requires extremely precise implant ranges, straggles and sample temperature, but the exact dose may not be critical. In this paper, two important application areas that have attracted much attention and research in the past 2 years, hydrogen PIII and the fabrication of low- k materials, are reviewed.