Ion Implantation Process Research Articles

Changes in local surface structure and Sr depletion in Fe-implanted SrTiO3 (001)

Local surface structure of single crystal strontium titanate SrTiO3 (001) samples implanted with Fe in the range of concentrations between 2×1014 to 2×1016Fe/cm2 at 30keV has been investigated. In order to facilitate Fe substitution (doping), implanted samples were annealed in oxygen at 350°C. Sr depletion was observed from the near-surface layers impacted by the ion-implantation process, as revealed by Rutherford Backscattering Spectrometry (RBS), X-ray photoelectron spectroscopy (XPS), X-ray Absorption Near Edge Spectroscopy (XANES), and Atomic Force Microscopy (AFM). Hydrocarbon contaminations on the surface may contribute to the mechanisms of Sr depletion, which have important implications for Sr(Ti1-xFex)O3-δ materials in gas sensing applications.

Estimation of the ionic charge of non-metallic species into an electrical discharge through a web application

Estimate the ionic charge generated in electrical discharges will allow us to know more accurately the concentration of ions implanted on the surfaces of nonmetallic solids. For this reason, in this research a web application was developed to allow us to calculate the ionic charge generated in an electrical discharge from the experimental parameters established in an ion implantation process performed in the JUPITER (Joint Universal Plasma and Ion Technologies Experimental Reactor) reactor. The estimated value of the ionic charge will be determined from data acquired on an oscilloscope, during startup and shutdown of electrical discharge, which will then be analyzed and processed. The study will provide best developments with regard to the application of ion implantation in various industrial sectors.

Detection and reduction of tungsten contamination in ion implantation processes

AbstractIn this paper, we review the results of some studies addressing the problem of tungsten contamination in implantation processes. For some tests, the implanter was contaminated by implantation of wafers with an exposed tungsten layer, resulting in critical contamination conditions. First, DLTS (deep level transient spectroscopy) measurements were calibrated to measure tungsten contamination in ion‐implanted samples. DLTS measurements of tungsten‐implanted samples showed that the tungsten concentration increases linearly with the dose up to a rather low dose (5×1010 cm–2). Tungsten deactivation was observed when the dose was further increased. Under these conditions, ToF‐SIMS revealed tungsten at the wafer surface, showing that deactivation was due to surface segregation. DLTS calibration could therefore be obtained in the linear dose regime only. This calibration was used to evaluate the tungsten contamination in arsenic implantations. Ordinary operating conditions and critical contamination conditions of the equipment were compared. A moderate tungsten contamination was observed in samples implanted under ordinary operating conditions. This contamination was easily suppressed by a thin screen oxide. On the contrary, implantations in critical conditions of the equipment resulted in a relevant tungsten contamination, which could be reduced but not suppressed even by a relatively thick screen oxide (up to 150 Å). A decontamination process consisting of high dose implantations of dummy wafers was tested for its efficiency to remove tungsten and titanium contamination. This process was found to be much more effective for titanium than for tungsten. Finally, DLTS proved to be much more sensitive that TXRF (total reflection X‐ray fluorescence) in detecting tungsten contamination. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Optimizing a blend of a mixture slurry in chemical mechanical planarization for advanced semiconductor manufacturing using a posterior preference articulation approach to dual response surface optimization

Semiconductors are fabricated through unit processes including photolithography, etching, diffusion, ion implantation, deposition, and planarization processes. Chemical mechanical planarization, which is essential in advanced semiconductor manufacturing processes, aims to achieve high planarity across the wafer surface. This paper presents a case study in which the optimal blend of mixture slurry was obtained to improve the two response variables (material loss and roughness) at the same time. The mixture slurry consists of several pure slurries; when all of the abrasive particles within the slurry are of the same size, the slurry is referred to as a pure slurry. The optimal blend was obtained by applying a multiresponse surface optimization method. In particular, the recently developed posterior approach to dual response surface optimization was employed, which allows the chemical mechanical planarization process engineer to investigate tradeoffs between the two response variables. The two responses were better with the obtained blend than the existing blend. Copyright © 2016 John Wiley & Sons, Ltd.

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.

Influence of Deuterium Treatments on the Polysilicon-Based Metal-Semiconductor-Metal Photodetector.

The electrical behavior of metal-semiconductor-metal (MSM) Schottky barrier photodetector structure, depending on deuterium treatment, is analyzed by means of the dark current and the photocurrent measurements. Al/Ti bilayer was used as Schottky metal. The deuterium incorporation into the absorption layer, undoped polysilicon, was achieved with annealing process and with ion implantation process, respectively. In the photocurrent-to-dark current ratio measurement, deuterium-ion-implanted photodetector shows over hundred higher than the control device. It means that the heightening of the Schottky barrier and the passivation of grain boundary trap were achieved effectively through the deuterium ion implantation process.

High-Performance 4H-SiC p-i-n Ultraviolet Photodiode With p Layer Formed by Al Implantation

In this letter, a high-performance 4H-SiC p-i-n ultraviolet (UV) photodiode (PD) with its p layer formed by Al implantation is designed and fabricated. The dark current density of the PD remains lower than 1 nA/cm2 at −100 V in the entire temperature range from room temperature (RT) up to 175 °C. The RT maximum external quantum efficiency of the PD under 0 V bias is 44.4% at 270 nm with a UV/visible rejection ratio larger than $10^{4}$ . The photoresponse characteristics of the PD are studied as the functions of reverse bias and temperature, which suggest that the device is advantageous to detect UV signals in high-temperature harsh environment. Compared with a 4H-SiC p-i-n PD formed entirely by epitaxial growth, the PD formed by Al implantation exhibits larger frequency dispersion in capacitance–voltage measurement, which should be caused by residual structural defects introduced during the ion implantation process.

Ion Implantation Defects in 4H-SiC DIMOSFET

In this paper the influence of point defects generated by the ion implantation process in 4H-SiC DIMOSFET has been studied in detail. The point defects generated by the source or body implantation process have been detected by micro-photoluminescence and the effect of these defects on the electrical characteristics of the DIMOSFET has been studied. In particular it has been observed that a reduction of the source ion implanted dose produces a large reduction of point defects in the source region and a considerable improvement of the electrical characteristic of the DIMOSFET.

Optimization of Ion Implantation processes for 4H-SiC DIMOSFET

AbstractIn this paper the defects generated by ion implantation in 4H-SiC DIMOSFET (Double Implanted MOSFETs), and their evolution after annealing process, have been studied in detail. The point defects generated by the source or body implantation process have been detected by micro-photoluminescence (µPL) and the effect of these defects on the electrical characteristics of the DIMOSFET has been studied. The role of the annealing process has been carefully investigated by using different temperatures. It appears fundamental for the restoring of the crystal damage. The effect of the ion implantation dose has been investigated as well. By reducing the source ion implanted dose a large decrease of point defects has been detected and a considerable improvement of the electrical characteristic of the DIMOSFET has been observed.

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.

Tungsten contamination in ion implantation

In this paper the tungsten contamination in ion implantation processes is studied by DLTS analysis both in typical operating conditions and after contamination of the implanter by implantation of wafers with an exposed tungsten layer. Of course the contaminant concentration is orders of magnitude higher after contamination of the implanter, but in addition our data show that different mechanisms are active in a not contaminated and in a contaminated implanter. A moderate tungsten contamination is observed also in a not contaminated implanter, however in that case contamination is completely not energetic and can be effectively screened by a very thin oxide. On the contrary, the contamination due to an implantation in a previously contaminated implanter is reduced but not suppressed even by a relatively thick screen oxide. The comparison with SRIM calculations confirms that the observed deep penetration of the contaminant cannot be explained by a plain sputtering mechanism.

Gas cluster ion beam assisted NiPt germano-silicide formation on SiGe

We report the formation of very uniform and smooth Ni(Pt)Si on epitaxially grown SiGe using Si gas cluster ion beam treatment after metal-rich silicide formation. The gas cluster ion implantation process was optimized to infuse Si into the metal-rich silicide layer and lowered the NiSi nucleation temperature significantly according to in situ X-ray diffraction measurements. This novel method which leads to more uniform films can also be used to control silicide depth in ultra-shallow junctions, especially for high Ge containing devices, where silicidation is problematic as it leads to much rougher interfaces.

A Thermal Method to Reduce the Polysilicon Resistance for Deep Submicron Integration Process

In the ultra-large-scale integration (ULSI) technologies, polysilicon resistors are usually employed in the integrated circuits as a precise analog resistor element for a variety of applications, such as DAC (digital resistor give the solution of the linearity and Rs concerns to analog converter) in analogue circuits [1-3]. Conventionally the polysilicon resistance can be adjusted by ion implantation and post annealing process [4]. For the self-aligned implantation process, the dosage changes which are always utilized to adjust the resistance are feasible to induce the MOS characteristics changes, especially in the submicron process whose short-channel effects (SCE) are much more sensitive to the dosages [5]. In this work, we propose a new inner anneal process in N2ambient after polysilicon re-oxidation to reduce the polysilicon resistance by changing the polysilicon grain size. The test patterns are manufactured on 300mm-diameter wafer by 65-nm 1-poly 7-metal standard CMOS technology. After polysilicon re-oxidation to form oxide film on polysilicon surface, the wafers are annealed at 800oC, 900oC, 950oC and 1000oC in N2ambient, respectively. Fig. 1 shows the process flow and annealing process steps in the flow. After anneal, the polysilicon grain size is measured by X-ray powder diffraction (XRD). And the electric characteristics for NMOS, PMOS and polysilicon resistance are tested. Fig. 2 shows the poly resistance reduction proportion and poly grain size after anneal at 800oC, 900oC, and 1000oC for 5min, and 950oC for 20min in N2 ambient, respectively. Only after annealing at 950oC or above for 5min, the resistance can be obviously reduced, due to the poly grain size increasing. Fig. 3 shows threshold voltages (Vt) variation proportions of NMOS and PMOS owning gate length of 65nm and width 0.12µm after utilizing annealing process at different temperatures. PMOS is more sensitive to the anneal process than NMOS. But after anneal at 950oC or below, the threshold variation for both NMOS and PMOS is less than 5%, which is acceptable for the integration process manufacturing. A new anneal process at N2 ambient to adjust the polysilicon resistance has been proposed. It has been verified that utilizing anneal process at 950oC or below, the 65nm MOS performances can be maintained almost same as before. Consequently, it is considered that the anneal method can be to be applied to the deep submicron integration process.

Molecular Dynamics Simulation on Hydrogen Ion Implantation Process in Smart-Cut Technology

The hydrogen ion implantation process in Smart-Cut technology is investigated in the present paper using molecular dynamics (MD) simulations. This work focuses on the effects of the implantation energy, dose of hydrogen ions and implantation temperature on the distribution of hydrogen ions and defect rate induced by ion implantation. Numerical analysis shows that implanted hydrogen ions follow an approximate Gaussian distribution which mainly depends on the implantation energy and is independent of the hydrogen ion dose and implantation temperature. By introducing a new parameter of defect rate, the influence of the processing parameters on defect rate is also quantitatively examined.

N and Cr ion implantation of natural ruby surfaces and their characterization

Energetic ions of N and Cr were used to implant the surfaces of natural rubies (low aesthetic quality). Surface colours of the specimens were found to change after ion implantation. The samples without and with ion implantation were characterized by diffuse reflectance spectra in ultra violet and visible region (DRS-UV–Vis), field emission scanning electron microscopy (FESEM), selected area electron diffraction (SAED) and nano-indentation. While the Cr-ion implantation produced deep red surface colour (pigeon eye red) in polished raw sample (without heat treatment), the N-ion implantation produced a mixed tone of dark blue, greenish blue and violet surface colour in the heat treated sample. In the case of heat treated sample at 3×1017N-ions/cm2 fluence, formation of colour centres (F+, F2, F2+ and F22+) by ion implantation process is attributed to explain the development of the modified surface colours. Certain degree of surface amorphization was observed to be associated with the above N-ion implantation.

Low resistivity lateral P–I–N junction formed by Ni–InGaAsP alloy for carrier injection InGaAsP photonic devices

In this study, we investigate low-resistivity InGaAsP lateral P–I–N junctions using Ni–InGaAsP alloy in conjunction with Zn diffusion. It is found that Ni–InGaAsP alloy is formed via a direct reaction between Ni and InGaAsP after annealing at more than 300 °C. The Ni–InGaAsP preserves the initial Schottky junction properties between Ni and InGaAsP, and thus exhibits an ohmic contact for n-InGaAsP and a Schottky contact for p-InGaAsP. Hence, the Ni–InGaAsP alloy can be used instead of the Si ion implantation process to form the P–I–N junction. The Ni–InGaAsP alloy exhibits significantly lower contact resistance and sheet resistance than Si implanted n+-InGaAsP. The InGaAsP lateral P–I–N junction formed with the Ni–InGaAsP alloy and Zn diffusion shows approximately 10 times lower access resistance than the n+-InGaAsP junction. Thus, we successfully achieve large on-current in the lateral P–I–N junction with the Ni–InGaAsP alloy. The fabrication procedure of the lateral P–I–N junction using the Ni–InGaAsP alloy is promising for carrier-injection photonic devices on the III–V CMOS photonics platform.

Spectral Ellipsometry and Electron Backscatter Diffraction Analyses of Silicon Surfaces Implanted with Silver Ions

Amorphous silicon (a-Si) produced on surfaces of single-crystal substrates (c-Si) by low-energy low-dose implantation of silver ions is studied by spectral ellipsometry and electron backscatter diffraction. Implantation was done with an ion energy of 30 keV at a constant ion beam current density of 2 μA/cm2 and doses of 6.24·1012–1.25·1016 ions/cm2 on room temperature substrate targets. Irradiation was carried out with a current density of 0.1–5 μA/cm2 for implantation doses of 6.24·1013 and 1.87·1014 ions/cm2. It was found that spectral ellipsometry is an accurate andreliable method for monitoring low-dose ion implantation processes.

Nano-thick calcium oxide armed titanium: boosts bone cells against methicillin-resistant Staphylococcus aureus.

Since the use of systemic antibiotics for preventing acute biomaterial-associated infections (BAIs) may build up bacterial resistance and result in huge medical costs and unpredictable mortality, new precaution strategies are required. Here, it demonstrated that titanium armed with a nano-thick calcium oxide layer was effective on averting methicillin-resistant Staphylococcus aureus (MRSA) infections in rabbits. The calcium oxide layer was constructed by, firstly, injecting of metallic calcium into titanium via a plasma immersion ion implantation process, and then transforming the outer most surface into oxide by exposing to the atmosphere. Although the calcium oxide armed titanium had a relative low reduction rate (~74%) in growth of MRSA in vitro, it could markedly promote the osteogenic differentiation of bone marrow stem cells (BMSCs), restore local bone integration against the challenge of MRSA, and decrease the incidence of MRSA infection with a rate of 100% (compared to the titanium control). This study demonstrated for the first time that calcium, as one of the major elements in a human body, could be engineered to avert MRSA infections, which is promising as a safe precaution of disinfection for implantable biomedical devices.

The structure, optical and magnetic properties of arsenic implanted ZnO films prepared by molecular beam epitaxy

Different concentrations of arsenic ions have been introduced into high quality O polar ZnO films prepared by rf-plasma assisted molecular beam epitaxy on sapphire substrates by ion implantation. Rutherford Backscattering/Channeling, x-ray diffraction, Raman spectroscopy and optical absorption measurements have been carried out to characterize the implantation induced disorder in the ZnO films. Room temperature ferromagnetism has been observed for the films implanted with As dose higher than 6×1018cm−3. The size of the observed moment is too large to be attributed to the As related defect complex (AsZn-2VZn) and is attributed to defects introduced by the ion implantation process. This was confirmed by the observation that the magnetization could be removed by annealing the films.

Dynamics of Faceted Nanoparticles Formation in a Crystalline Matrix During Ion Implantation Processing.

The faceted nanoparticle synthesized by ion implantation, such as Zn, Cu or Ag nanoparticles, is one of the promising materials for the next generation of optical devices. To understand and better control the manufacturing processes of ion implantation, a theoretical model is applied to investigate the formation and evolution of faceted nanoparticles under various experimental conditions of implantation processing. In this study, the mechanisms of the anisotropic interfacial energy and kinetics with different ion distributions are taken into consideration to demonstrate the role of the crystallographic symmetry, ion energy and temperature on the faceted nanoparticles formation in a crystalline matrix. As presented in the numerical results, the morphological shape of the nanoparticles is mainly affected by the crystallographic symmetry, while the distribution of the precipitates is principally determined by the ion energy. For the condition of high-temperature implantation, a high mobility of ions causes the characteristic length of nanostructures to increase and creates a coarsening morphology of nanoparticles. It is attributed to a longer diffusion distance during the nucleation and growth processes. This model can be widely used for the predictions of the nanostructures formation with various ion implantation processes.