Plasma Immersion Ion Implantation Implants Research Articles

Plasma Immersion Ion Implantation of a Fe-Mn-C Based Steel for Biomedical Applications: Effect of Gases and Treatment Times on the Surface Properties

Current research on biodegradable iron-based alloys mainly focuses at regulating the material degradation rate, as well as its biological behavior, especially from the point of view of the hemocompatibility and cytocompatibility. In fact, fine-tuning of the surface roughness, morphology and chemical composition can improve the functional response of the material. For that purpose, a surface modification strategy, namely plasma immersion ion implantation (PIII), is proposed to perform the selective modification of surface properties without affecting the bulk ones. In this work, the influence of treatment time (timp = 15, 60 and 120 min.) and implanted species (O, N or C) on the surface properties of a Fe-13Mn-1.2C resorbable alloy was investigated. The findings demonstrated that varying the process gas and the exposition time led to a variety of topographies, surface energies and chemical compositions. XPS analyses and depth profiles clearly showed the impact of the process parameters on the surface features and element distribution, due to implanted species penetration into the alloy. The implanted samples showed a delayed clotting time, thus a better hemocompatibility. In contrast, nitrogen-treated surfaces displayed a more pronounced hemolytic behavior, whereas oxygen and methane did not. PIII implantation appears to be a versatile solution for fine-tuning surface topography, composition and biological properties, making the process promising for the improvement of metallic biodegradable vascular implants.

Plasma‐immersion ion implantation: A path to lower the annealing temperature of implanted boron emitters and simplify PERT solar cell processing

AbstractIon implantation is a suitable and promising solution for the massive industrialization of boron doping, which is a crucial process step for most next‐generation solar cells based on crystalline silicon (c‐Si). However, the use of ion implantation for boron doping is limited by the high temperature (in the 1050°C range) of the subsequent activation anneal, which is essential to dissolve the boron clusters and reach a high‐emitter quality. In this work, we propose the use of plasma‐immersion ion implantation (PIII) from B2H6 gas precursor instead of the standard beamline ion implantation (BLII) technique to decrease this temperature down to 950°C. PIII and BLII boron emitters were compared with annealing temperatures ranging from 950°C to 1050°C. Contrary to BLII, no degradation of the emitter quality was observed with PIII implants annealed at 950°C along with a full activation of the dopants in the emitter. At 1000°C, emitter saturation current densities (J0e) below 21 fA/cm2 were obtained using the PIII technique regardless of the tested implantation doses for sheet resistances between 110 and 160 Ω/sq. After metallization steps, the metal/emitter contact resistances were assessed, indicating that these emitters were compatible with a conventional metallization by screen‐printing/firing. The PIII boron emitters' performances were further tested with their integration in n‐type passivated emitter rear totally diffused (PERT) solar cells fully doped by PIII. Promising results already show a conversion efficiency of 20.8% using a lower annealing temperature than with BLII and a reduced production cost.

Large boron‐interstitial cluster modelling in BF3 plasma implanted silicon

AbstractBF3 plasma immersion ion implantation (PIII) is a promising technique in the race for highly boron doped P+/N ultra‐shallow junctions (USJs) in complementary metal oxide semiconductor (CMOS) silicon technologies. Implantation conditions used in BF3 PIII lead to high super‐saturations (≥1 × 1020 cm–3) of both boron and silicon interstitial atoms in the implantation region. In such conditions, very large loop‐shaped boroninterstitial clusters (BICs) are formed during subsequent thermal anneals, as confirmed by transmission electron microscopy (TEM) measurements.In this study, amorphizing BF3 PIII implants (10 keV, 5 × 1015 cm–2) followed by different thermal anneals were carried out in order to investigate the large BICs precipitation. A ”large BICs“ model based on moments approach allowed to reproduce the experimental data including boron diffusion profiles (obtained by SIMS) and boron electrical activation obtained by Hall effect sheet resistance measurements.(© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Surface modification of indium tin oxide by oxygen plasma immersion ion implantation

Organic electroluminescent device, also known as organic light-emitting diode (OLED), is a kind of solid state light emitting device by carrier injection which can directly transform electrical energy into luminous energy. Due to its low operating voltage, low energy consumption, high brightness, flexibility in the choice of materials and easy realization of full color display, OLED is the potential material both in the display and illumination fields. However, there is much scope to improve the efficiency, lifetime, and reduce the cost in mass production before OLEDs can replace traditional technology in some application fields. In this work, we report the oxygen plasma immersion ion implantation (PIII) to improve the surface oxygen ratio of ITO films for further increase of surface work function above the common treatment of O2 inductively coupled plasma (ICP). The ratio of oxygen content at the surface layer was improved to be much higher than by O2 ICP treatment. A further surface work function relative increase of 0.4 eV above OICP sample and 0.4 eV above the as-prepared sample can be estimated by the peak relative shift in the X-ray photoelectron spectroscopy (XPS) diagram. Moreover, the XPS characterization was carried out at least 50 h after the PIII implantation to indicate that the surface modifying effects are stable. The variations of transparency and conductivity of the PIII treated ITO samples can be neglected.

A novel technique for tailored surface modification of dental implants – a step wise approach based on plasma immersion ion implantation

A novel technique based on plasma immersion ion implantation (PIII) is presented to modify titanium implant surfaces. Initially, the implants are cleaned with argon to remove contaminants and the nanostructures are created by the bombardment of the surface with a mix of noble gases. Desired crystal structure of the titanium is obtained by the implantation of oxygen on the contaminant-free surface with particular nanostructures. In this study, turned implants modified by PIII revealed a high density of rutile-TiO2 nanostructures. Turned implants used as control revealed mainly microstructures and amorphous crystal structure. Surface roughness values were similar at the microscale for both turned and turned+PIII implants. Bone response was evaluated by removal torque tests of implants placed in the rabbit tibia and femur. After 4weeks of healing, turned+PIII demonstrated higher removal torque values (P=0.001) compared to turned implants. The presence of rutile-TiO2 nanostructures may explain the improved bone formation to turned+PIII implants.

Application of Plasma Immersion Ion Implantation for improved performance of tools and industrial components

Surface processing of tools and other industrial components was carried out by Plasma Immersion Ion Implantation (PIII) for the improvement of their tribological properties and consequently to reach their prolonged lifetime. Tools made of different types of steels, mainly for the production of rivets, had their lifetime extended for up to 70 times, reducing cost and improving productivity in a mass producing line. Metallic samples used in components for prosthesis (CrNiMo) showed improvements in hardness of up to 250% after nitrogen PIII while non-conducting polymer used also for prosthesis component (UHMWPE) was hardened significantly due to the formation of a DLC layer in the treated surface. Tungsten carbide tools were also nitrogen PIII processed which resulted in some improvement in their lifetime but more importantly in excellent surface finishing of the produced Ti parts for dental implants. Steel samples made from H13 alloy showed successful PIII implantation profile (up to depths of 18 μm) and improved hardness of a factor of two was obtained. These results for H13 steel point toward successful applications in molds and other industrial components.

Modeling of energy distributions for plasma implantation

Plasma immersion ion implantation (PIII) has significant advantages over conventional implantation in high dose and low energy implant applications. One potential drawback is the poly-energetic nature of pulsed PIII implantation. The contribution of low energy ions to the total implant dose has been computed for pulsed PIII. An analytical approach allows the extraction of the scaling of the dose of the low energy with the implant parameters. The developed models allow the engineering of the rise times, fall times, total pulse time, pulsing frequency, and plasma ion density to minimize the implant energy spread, while maximizing the dose rate.

Plasma doping dosimetry

Plasma immersion ion implantation (PIII) is a large-area doping technique that can provide very high implant current at very low implant energy. Multiple ion species, plasma conditions, and implanter current-voltage waveforms in PIII lead to an exponential implant profile which is different from conventional implant profiles. A methodology is developed for using in situ measurements of the implanter current (I) and implant voltage (V) to derive an energy spectrum for a single implant pulse. The advantage of this technique is that a per-pulse profile may be determined experimentally, even in the presence of substrate etching, without any need for an implant model. If the ion species concentrations in the plasma are known, the energy spectrum found from the ion current and voltage waveforms can be used to construct a per-pulse implant profile. If the ion species distribution is not known a priori for a multispecies plasma, secondary ion mass spectroscopy (SIMS) data from an implanted sample can be used to estimate the ion species distribution and calibrate the IV-generated profile within a factor of two. Data from 1-5 kV, 2.5-5 kHz BF/sub 3/ PIII implants are used to demonstrate the concept. The implant profile for a single pulse can then be used to project the final implant profile and total implanted dose as a function of implant time, Pm pulse frequency, and substrate etching. In this work, an estimated secondary electron yield function is used to separate the total implant current into ion and secondary electron current components. The 25% dose variation error introduced by this effective secondary electron yield function could be avoided in a system which can measure ion current directly.