High Temperature Ion Implantation Research Articles

(Digital Presentation) Substrate Effects in GaN-on-Si Hemt Technology for RF FEM Applications

: GaN-on-Si HEMTs are emerging as a viable candidate for front-end-of-module (FEM) implementation in 5G and beyond user equipment and small-cell applications [1][2]. This is because GaN HEMTs based power amplifiers and switches have high power handling capability as well as excellent switch figure-of-merit (Ron × Coff). The cost-effective integration of GaN HEMTs on silicon substrates not only benefit from standard CMOS back-end-of-the-line processing but also wafer-level integration with Si-CMOS [1][3], enabling complex functionality and better performance than the standalone counterparts. An example can be a hybrid beamformer where GaN HEMTs can enable much smaller antenna array and therefore a smaller system form factor. For 5G wireless applications, standalone or co-integrated GaN HEMT based FEMs can lead to a more energy efficient and compact system as compared to standalone Si-CMOS technologies. However, for both amplifiers and switches, GaN-on-Si HEMTs present thermal management and substrate loss related issues. In this work, we study and model the impact of GaN HEMT integration on Si substrate on RF substrate losses and non-linearities. The growth of III-N buffer is the most significant factor in determining RF losses and harmonic distortion contribution from the substrate. High temperature annealing and ion implantation steps encountered during HEMT processing can also degrade the substrate performance. In addition, we demonstrate a direct co-relation between substrate losses and harmonic distortion analogous to silicon-on-insulator technologies (Figure 1). However, the bias dependence of RF losses and harmonics show a strong time dependence (memory effects) which is more complex to model [11]. We discuss the approaches to understand and model these effects.

Microstructural Evolution and the Irradiation Sensitivity of Different Phases of a High Nb-Containing TiAl Alloy under He Ions Implantation at Room- and Elevated Temperatures

A high Nb-containing TiAl alloy Ti-45Al-8.5Nb-(W, B, Y) with nearly lamellar microstructure has been irradiated by 200 kV He2+ to a fluence of 1 × 1021 ions/m2 with a dose of about 1.1 dpa at 298 K and 773 K in this work. It is found that an amorphous layer formed on the surface, and no helium bubbles can be observed in the alloy after room temperature ion implantation. The surface roughness of the alloy increases significantly with the bombardment of helium ions, indicating that the ion implantation increases the surface defects. The high-temperature ion implantation leads to the phenomenon of blistering on the alloy surface, and helium bubbles are observed in both α2 and γ phases of the alloy irradiated at 773 K. The average size of the helium bubbles in the α2 (15~20nm) is larger than that in the γ (3~5 nm) phase, while the helium bubble density is opposite. Moreover, the growth mechanism of helium bubble is also investigated. By means of nanoindentation, an obvious irradiation hardening phenomenon is measured after the room temperature ion implantation. In addition, the irradiation sensitivity of different phases is also discussed in this work. The results show that the γ phase has the highest irradiation sensitivity, α2 phase second, β phase minimum. The results of this work, especially microstructure evolution and the evaluation of phase-related irradiation sensitivity during ion implantation, can be expected to provide experimental evidence for the applications of TiAl intermetallic compounds in the nuclear industries.

The Influence of High-Temperature Nitrogen Plasma-Based Ion Implantation on Niobium Creep Behavior

Niobium has been considered for applications in the aerospace sector, but its use at high temperatures is restricted, due to the great affinity of refractory metals with oxygen, which results in the formation of oxide layers and a decrease in their mechanical resistances. In the present work, Nb samples were submitted to High-Temperature Nitrogen Plasma-Based Ion Implantation (HT-NPBII). The process runs at a working pressure between 3 and 4 mbar and negative high voltage pulses of 7 kV/30 μs/300 Hz were applied to samples heated to 1000°C, at treatment times of 1 h, 4 h, and 8 h, respectively. Microstructural and mechanical characterizations of the treated samples revealed the formation of a layer of Nb2N, with 3.0 μm thickness and increase in the surface hardness from 225 HV for the untreated material up to about 2498 HV, for samples treated during 8 h. Creep tests were performed at 500°C and with loads varying from 25 to 40 MPa. Results indicated a decrease in the secondary creep rate for treated specimens when compared to the untreated ones. This behavior can be attributed to the formation of a nitride layer on the surface of Nb that acts as barrier to avoid the oxygen diffusion into the material under high temperature conditions.

Angular rotation ion implantation technology in SiC for 4H-SiC junction barrier Schottky rectifiers

• This study proposes an angular rotation ion implantation technology. • This technology could improve the rate of finished product products to be 90%. • With the angle rotation technology, the production cost will be saved effectively. SiC is widely used for making high level power electronic devices due to its excellent properties. SiC Junction Barrier Schottky (JBS) diodes have a low reverse leakage current and could offer fast switching and the Schottky-like on-state characteristics. High temperature ion implantation has been an essential process for the mainly doping formation SiC power electronic devices. In this work, the angular rotation ion implantation technology in SiC JBS has been investigated. The distribution of the injected elements has also been simulated, and the calculated results fitted well with the experimental results. With this angular rotation technology the power loss of the SiC JBS diodes have been reduced, effectively. And the rate of finished product was turned out to be as high as 90%. This method can greatly reduce the process flow, reduce the damage to the wafer and save production cost, which has great significance in quantity production.

Improvement in drain-induced-barrier-lowering and on-state current characteristics of bulk Si fin field-effect-transistors using high temperature Phosphorus extension ion implantation

In this paper, high temperature Phosphorus ion implantation is applied to p-type Si (1 0 0) substrates and n-type bulk Si fin field-effect-transistors. Phosphorus profiles and sheet resistance on p-type Si (1 0 0) substrates are analyzed. High temperature ion implantation shows less Phosphorus diffusion after rapid thermal annealing compared to room temperature ion implantation. In n-type bulk Si fin field-effect-transistors with wide spacers and ion implanted source and drain, the high temperature extension ion implantation shows better electrical characteristics in terms of drain-induced-barrier-lowering, on-state resistance, on-state current, and off-state current. In n-type bulk Si fin field-effect-transistors with narrow spacers and Phosphorus in-situ doped Si epi source and drain, drain-induced-barrier-lowering and off-state current characteristics are improved by high temperature extension ion implantation, compared to room temperature extension ion implantation. Phosphorus distribution in fin field-effect-transistors is analyzed by scanning spreading resistance microscopy. Suppression of Phosphorus diffusion into the channel area is confirmed.

Retraction Note to: Investigation of Co-Doped ZnO Nanowires by X-ray Absorption Spectroscopy and Ab Initio Simulation

The local structure of single room- and high-temperature Co-implanted ZnO nanowires with subsequent thermal annealing has been studied using hard-x-ray techniques in combination with ab initio Zn K-edge x-ray absorption near-edge structure (XANES) simulations. X-ray fluorescence data reveal a homogeneous distribution of Co atoms/ions with concentration of about 0.1 at.% to 0.3 at.% in the nanowires. XANES data indicate substitutional incorporation of Co2+ ions at Zn sites in both types of nanowire. Improved structural order around Co atoms is obtained in nanowires with high-temperature ion implantation followed by thermal annealing. The ab initio Zn K-edge simulations not only confirm recovery of implantation-induced damage in the ZnO host lattice by the thermal annealing process, but also assist in studying the effect of oxygen vacancies in the Zn K-edge XANES spectra. Microphotoluminescence data certify that high-temperature ion implantation with subsequent thermal annealing is an effective approach to achieve the strongest optical activation of Co ions and good energy transfer to Co ions from the ZnO host matrix.

Formation of D-Center in p-Type 4H-SiC Epi-Layers during High Temperature Treatments

The current work is devoted to studying the evolution of deep level defects in the lower half of the 4H-SiC bandgap after high temperature processing and ion implantation. Two as-grown and pre-oxidized 4H-SiC sets of samples have been thermally treated at temperatures up to 1950 °C for 10 min duration using RF inductive heating. Another set of as grown samples was implanted by 4.2 MeV Si ions at room temperature (RT) with different doses (1-4×108 cm-2). The so-called “D-center” at EV+0.6 eV dominates and forms after the elevated heat treatments, while it shows no change after the ion implantations (EV denotes the valence band edge). In contrast, the concentration of the so-called HK4 level at EV+1.44 eV increases with the implantation dose, whereas it anneals out after heat treatment at ≥ 1700 °C.

RETRACTED ARTICLE: Investigation of Co-Doped ZnO Nanowires by X-ray Absorption Spectroscopy and Ab Initio Simulation

The local structure of single room- and high-temperature Co-implanted ZnO nanowires with subsequent thermal annealing has been studied using hard-x-ray techniques in combination with ab initio Zn K-edge x-ray absorption near-edge structure (XANES) simulations. X-ray fluorescence data reveal a homogeneous distribution of Co atoms/ions with concentration of about 0.1 at.% to 0.3 at.% in the nanowires. XANES data indicate substitutional incorporation of Co2+ ions at Zn sites in both types of nanowire. Improved structural order around Co atoms is obtained in nanowires with high-temperature ion implantation followed by thermal annealing. The ab initio Zn K-edge simulations not only confirm recovery of implantation-induced damage in the ZnO host lattice by the thermal annealing process, but also assist in studying the effect of oxygen vacancies in the Zn K-edge XANES spectra. Microphotoluminescence data certify that high-temperature ion implantation with subsequent thermal annealing is an effective approach to achieve the strongest optical activation of Co ions and good energy transfer to Co ions from the ZnO host matrix.

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.

High dopant activation of phosphorus in Ge crystal with high-temperature implantation and two-step microwave annealing

In this letter, high-temperature ion implantation and low-temperature microwave annealing were employed to achieve high n-type active concentrations, approaching the solid solubility limit, in germanium. To use the characteristics of microwave annealing more effectively, a two-step microwave annealing process was employed. In the first annealing step, a high-power (1200 W; 425 °C) microwave was used to achieve solid-state epitaxial regrowth and to enhance microwave absorption. In the second annealing step, contrary to the usual process of thermal annealing with higher temperature, a lower-power (900 W; 375 °C) microwave process was used to achieve a low sheet resistance, 78Ω/◻, and a high carrier concentration, 1.025 × 1020 P/cm3, which is close to the solid solubility limit of 2 × 1020 P/cm3.

High Dopant Activation and Diffusion Suppression of Phosphorus in Ge Crystal with High-Temperature Implantation By Two-Step Microwave Annealing

In this Letter, high-temperature ion implantation and low-temperature microwave annealing were employed to achieve maximum n-type active concentration, which can be fully activated in germanium. To use the characteristic of microwave annealing more effectively, two-step microwave annealing was also employed. In the first step annealing, a high-power (1200 W; 425 °C) microwave was used to achieve solid-state epitaxial regrowth (SPER) and enhance microwave absorption. In the second step of annealing, unlike in conventional thermal annealing, which requires a higher energy to activate the dopant, a low-power (900W;375 °C) microwave was used to achieve lowest sheet resistance 78Ω/□ and maximum active concentration 1.025×1020 P/cm3, which close to its solid solubility limit of 2×1020 P/cm3.

High Dopant Activation and Diffusion Suppression of Phosphorus in Ge Crystal with High-Temperature Implantation By Two-Step Microwave Annealing

In this paper, high-temperature ion implantation and low-temperature microwave annealing were employed to achieve maximum n-type active concentration, which can be fully activated in germanium. To use the characteristic of microwave annealing more effectively, two-step microwave annealing was also employed. In the first step annealing, a high-power (1200 W; 425 °C) microwave was used to achieve solid-state epitaxial regrowth (SPER) and enhance microwave absorption. In the second step of annealing, unlike in conventional thermal annealing, which requires a higher energy to activate the dopant, a low-power (900W;375 °C) microwave was used to achieve lowest sheet resistance 78Ω/□ and maximum active concentration 1.025×10 20 P/cm 3 , which close to its solid solubility limit of 2×10 20 P/cm 3 . Figure 1

Wafer-scale synthesis of multi-layer graphene by high-temperature carbon ion implantation

We report on the synthesis of wafer-scale (4 in. in diameter) high-quality multi-layer graphene using high-temperature carbon ion implantation on thin Ni films on a substrate of SiO2/Si. Carbon ions were bombarded at 20 keV and a dose of 1 × 1015 cm−2 onto the surface of the Ni/SiO2/Si substrate at a temperature of 500 °C. This was followed by high-temperature activation annealing (600–900 °C) to form a sp2-bonded honeycomb structure. The effects of post-implantation activation annealing conditions were systematically investigated by micro-Raman spectroscopy and transmission electron microscopy. Carbon ion implantation at elevated temperatures allowed a lower activation annealing temperature for fabricating large-area graphene. Our results indicate that carbon-ion implantation provides a facile and direct route for integrating graphene with Si microelectronics.

Sensitivity of CoSi2 precipitation in silicon to extra-low dopant concentrations. II. First-principles calculations

The paper is the second part of the study on the influence of very low dopant content in silicon on CoSi2 precipitation during high-temperature cobalt ion implantation into transmission electron microscope samples. It deals with the computational justification of various assumptions used in Paper I when rationalizing the kinetics of cobalt clustering in ion-implanted intrinsic silicon (both undoped and containing low concentrations of phosphorus atoms). In particular, it is proven that divacancies are efficient nucleation centers for the new Co-Si phase. It is shown that the capture of vacancies and divacancies on phosphorus atoms increases their lifetime in silicon matrix, but practically does not affect the mechanism of their interaction with interstitial cobalt atoms. Finally, it is demonstrated that the mobility of phosphorus interstitials at temperatures of our experiment is orders of magnitude higher than might be expected from the published literature data.

Carbon redistribution and precipitation in high temperature ion-implanted strained Si/SiGe/Si multi-layered structures

We report on the segregation of carbon atoms and structural transformations in strained multilayered Si/SiGe/Si structures after molecular-beam epitaxial (MBE) growth, carbon ion implantation and thermal treatment at different conditions. The idea behind this study was that due to their specific strain distribution, pseudomorphic layers of Si/SiGe promote spatial separation of vacancies and interstitials followed by segregation of foreign dopant atoms. High temperature ion implantation was used for injection of carbon atoms as well as point defects in the strained layers. The defects were investigated by transmission electron microscopy (TEM), dopant depth profiles by secondary-ion-mass spectrometry (SIMS), and optical properties by Raman scattering measurements. Based on SIMS data we demonstrate anomalous redistribution of the implanted carbon atoms around the strained SiGe/Si layers which results in their accumulation on the Si side and depletion on the SiGe side of the structure. The TEM study demonstrates formation of plate-like defects, stacking faults and thin carbon-precipitated flakes distributed along the Si/SiGe interfaces. Raman spectra reveal peaks at 1600 and 2700cm−1 which might be associated with carbon-related phases. The concept of strain-enhanced separation of point defects and dopant precipitation is discussed.

Laser plasma ion implantation and deposition of platinum for SiC-based hydrogen detector fabrication

A pulsed plasma plume obtained by pulsed laser irradiation of a Pt target was used to fabricate a hydrogen sensor on a 6H–SiC single crystal by means of ion implantation followed by thin film deposition. To realize the ion implantation, high voltage pulses with positive polarity were applied to the Pt target when the laser plasma expanded from the target to the SiC substrate. Experimental diagnostics of pulsed ion beams extracted from laser-produced plasma were performed and the structure of the SiC crystal after high-temperature (500°C) ion implantation was studied by Rutherford backscattering spectroscopy of 4He+ ions. At the same time, a one-dimensional model of the plasma movement in a pulsed electric field was developed and simulations were carried out using the particle-in-cell method. Modeling allowed determination of the ion energy distribution depending on the delay time of the high voltage pulse after the laser pulse. The calculated energy distribution of Pt ions was used to predict the depth profile of implanted Pt ions in the SiC substrate. The predicted profile agreed sufficiently well with the experimentally measured depth distribution of Pt in the SiC substrate. To characterize the fabricated SiC sensor, the current flow through a barrier structure was studied. The volt–ampere characteristics of the structure were measured in air and in a mixture of air and hydrogen (2%) at a temperature of 500°C. The characteristic value of the change in voltage exceeded 2V at the bias current of 1mA when hydrogen was added to the air. The response of the sensor to the hydrogen was stable after long-term tests while the structure of the Pt film was disturbed. The ion-implanted layer operated as a series resistance, which had a significant effect on the current flow through the barrier structure. The resistance decreased under the influence of hydrogen and persisted during long-term tests.

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.

Multicomponent nanostructured films for various tribological applications

Abstract Many engineering materials working under severe cutting, stamping, or bearing conditions including humid and corrosive environments, as well as temperature fluctuation require a combination of chemical, mechanical, and tribological properties. For load-bearing metallic implants, the combination of excellent mechanical and tribological properties with biocompatibility and bioactivity is also of great importance. Desired properties can be achieved in hard films based on carbides, borides and nitrides of transition metals by alloying with metallic (Al, Cr, Zr) or nonmetallic (O, P, Si, Ca) elements. The present work demonstrates the potential of self-propagating high-temperature synthesis (SHS), magnetron sputtering (MS), and ion implantation assisted MS of SHS-composite targets to produce multicomponent nanostructured films with enhanced combination of properties. Three groups of recently developed films for mechanical engineering and medicine are considered: hard tribological Ti–(Al, Cr)–(Si, B, C, N) films with enhanced thermal stability, corrosion and oxidation resistance; nanocomposite and multilayered TiCrBN/WSe x films with improved lubrication; and multifunctional bioactive nanostructured (Ti, Ta)–(Ca, Zr)–(C, N, O, Si, P) films (MuBiNaFs).

High Temperature Ion Implantation: a Solution for n-Type Junctions in Strained Silicon

Elastic strain intentionally applied to thin layers can be reduced or even completely relaxed by amorphization during ion implantation. Sb implantation and activation in unstrained and strained-SOI substrates and effects on the crystal quality for different implantation conditions were investigated. Implantation induced amorphization can be avoided and simultaneously high dopant activation up to 55% can be achieved by implanting at elevated temperature. For a low implantation energy of 6 keV, no dopant profile broadening is measured after dynamic annealing in strained-SOI.

Quantitative analysis of the lattice reconstruction of ion-implanted SiC after visible light laser irradiation

We report on a quantitative analysis of the effect of visible light laser irradiation (VLLI) on hexagonal (α) silicon carbide implanted with nitrogen and aluminum. In both cases of 4H and 6H polytypes we show that a short, but intense, irradiation with the 532 nm wavelength of a frequency-doubled neodymium: ytterbium aluminum garnet (Nd:YAG) laser results in a substantial reduction in the damage level produced by room temperature ion implantation. Up to now the recovery could not be made complete but, in the best conditions, it could reach ∼80% of the initial damage value. This is not enough to qualify VLLI as a full activation step but, rather, suggests to use it as a new processing tool in order to lower the constraints of high temperature ion implantation or, after implantation performed at room temperature, to reduce the total budget for high temperature annealing and activation steps.