Ar Neutral Beam Research Articles

Constructing a Heterostructural LiNi0.4Mn1.6O4-δ Material from Concentration-Gradient Framework to Significantly Improve Its Cycling Performance.

A heterostructural LiNi0.35Mn1.65O4-δ-LiNi0.5Mn1.5O4 was achieved via constructing the concentration-gradient material with an average composition of LiNi0.4Mn1.6O4-δ. The as-obtained samples were characterized by cross-sectional scanning electron microscopy and energy dispersive X-ray spectrometry, and it was found that the core material LiNi0.35Mn1.65O4-δ is encapsulated completely by a concentration-gradient shell with the outmost layer of LiNi0.5Mn1.5O4. Demonstrated by high resolution transmission electron microscopy and X-ray photoelectron spectroscopy analysis with a low-energy Ar neutral beam etching method, the structurally stable P4332 phase on the surface coordinates the high conductive Fd3̅m phase in the bulk without any detectable interface. At room temperature, the heterostructural samples deliver the initial discharge capacity of 145.1 mAhg-1 at 1 C, close to the theoretical capacity, and the capacity retention after 300 cycles was up to 96.5% of the first discharge capacity. Moreover, it shows excellent rate capability with discharge capacity of 144.3 mAhg-1 at 10 C and significantly improved cycling stability with capacity retention of 85.51% over 50 cycles between 3.0 and 4.95 V at 55 °C. The as-obtained material with coordination of two crystallographic structure domains is a promising cathode to develop high energy, high power, long lifespan, and low cost lithium-ion batteries.

Reactive etching by ClF3–Ar neutral cluster beam with scanning

A reactive gas cluster injection system with a scanning function was developed in order to increase the processing area. High-precision anisotropic etching with an aspect ratio of 7 was achieved for ClF3 cluster etching without scanning. However, with scanning, the aspect ratio for etching decreased to 1.5 because the side walls were etched by the gas retained in the trench. By reducing the source gas pressure, increasing the target distance, and mixing He in the source gas, anisotropic etching with an aspect ratio of about 6.3 was achieved with this apparatus.

Understanding time-resolved processes in atomic-layer etching of ultra-thin Al2O3 film using BCl3 and Ar neutral beam

We scrutinize time-resolved processes occurring in atomic-layer etching (ALET) of ultra-thin Al2O3 film using BCl3 gas and Ar neutral beam by employing density functional theory calculations and experimental measurements. BCl3 gas is found to be preferentially chemisorbed on Al2O3(100) in trans form with the surface atoms creating O-B and Al-Cl contacts. We disclose that the most likely sequence of etching events involves dominant detachment of Al-associated moieties at early etching stages in good agreement with our concurrent experiments on tracking Al2O3 surface compositional variations during Ar bombardment. In this etching regime, we find that ALET requires half the maximum reaction energy of conventional plasma etching, which greatly increases if the etching sequence changes.

Development of Neutral Beam Source Using Electron Beam Excited Plasma

A low-energy neutral beam (NB) source, which consists of an electron-beam-excited plasma (EBEP) source and two carbon electrodes, has been developed for damageless etching of ultra-large-scale integrated (ULSI) devices. It has been confirmed that the Ar ion beam energy was controlled by the acceleration voltage and the beam profile had good uniformity over the diameter of 80 mm. Dry etching of a Si wafer at the floating potential has been carried out by Ar NB. Si sputtering yield by an Ar NB clearly depends on the acceleration voltage. This result shows that the NB has been generated through the charge exchange reaction from the ion beam in the process chamber.

Development of higher performance indium tin oxide films at a very low temperature (< 80 °C) by the neutral beam-assisted sputtering process

At very low temperatures (< 80 °C), improved performance indium tin oxide (ITO) thin films with a low resistivity of 4.22 × 10 −4 Ωcm and high transmittance > 90% at 550 nm were developed using the neutral beam-assisted sputtering (NBAS) technique, which included a cyclic inter-treatment process with an Ar neutral beam. Transmission electron microscopy and electron diffraction showed that the neutral particles with hyper-thermal energy was able to enhance the formation of the nano-crystalline phase and activate the dopant without additional heating or plasma damage during ITO thin film deposition.

200-mm-diameter neutral beam source based on inductively coupled plasma etcher and silicon etching

The authors developed a neutral beam source consisting of a 200-mm-diameter inductively coupled plasma etcher and a graphite neutralization aperture plate based on the design of a neutral beam source that Samukawa et al. [Jpn. J. Appl. Phys., Part 2 40, L779 (2001)] developed. They measured flux and energy of neutral particles, ions, and photons using a silicon wafer with a thermocouple and a Faraday cup and calculated the neutralization efficiency. An Ar neutral beam flux of more than 1 mA/cm2 in equivalent current density and a neutralization efficiency of more than 99% were obtained. The spatial uniformity of the neutral beam flux was within ±6% within a 100 mm diameter. Silicon etching using a F2-based neutral beam was done at an etch rate of about 47 nm/min, while Cl2-based neutral beam realized completely no undercut. The uniformity of etch rate was less than ±5% within the area. The etch rate increased by applying bias power to the neutralization aperture plate, which shows that accelerated neutral beam was successfully obtained. These results indicate that the neutral beam source is scalable, making it possible to obtain a large-diameter and uniform neutral beam, which is inevitable for application to mass production.

Plasma-Induced Deterioration of Mechanical Characteristics of Microcantilever

We investigated the effects of the defects generated by plasma in a silicon (Si) microcantilever. The E' center density of the microcantilever was markedly increased after argon (Ar) plasma irradiation. On the other hand, the E' center density could be effectively suppressed when using Ar neutral beam (NB). The mechanical characteristics, including the Q factor and resonant frequency, of a microcantilever were markedly decreased by plasma irradiation, which revealed that plasma irradiation deteriorated the mechanical characteristics of the micro element. These results have a considerable impact on micro- and nano-electro-mechanical systems (MEMSs/NEMSs). On the other hand, for NB irradiation, both characteristics were basically unchanged after irradiation, which indicates that the NB process is an ultralow-damage process. Therefore, the NB process may have tremendous potential to play an important role in the micro- and nano-fabrication processes.

Etch Characteristics of TiO2 Etched by Using an Atomic Layer Etching technique with BCl3 Gas and an Ar Neutral Beam

Etch Characteristics of TiO2 Etched by Using an Atomic Layer Etching technique with BCl3 Gas and an Ar Neutral Beam

Low Damage Atomic Layer Etching of ZrO2 by Using BCl3 Gas and Ar Neutral Beam

This study examined the etch characteristics of ZrO2 etched using an atomic layer etching (ALET) system with BCl3 gas for adsorption and an Ar neutral beam for desorption. The effect of the BCl3 gas pressure and Ar neutral beam dose on the etch characteristics was examined. The results showed that the ZrO2 etch rate was maintained at a constant etch rate of 1.07 angstroms/cycle at a BCl3 gas pressure > 0.15 mTorr and an Ar beam flux > 1.485 x 1016 atoms/cm2 x cycle. Under these constant etch rate conditions, the surface roughness of the etched ZrO2 was similar to that of the as-received ZrO2. The surface composition of ZrO2 etched by ALET was compared with that etched by BCl3 inductively coupled plasma (ICP). The surface composition of ZrO2 etched by ALET showed a similar composition to that of the as-received ZrO2 while that etched by BCl3 ICP showed a Zr-rich surface.

Improvement of electron field emission from carbon nanotubes by Ar neutral beam treatment

To improve the field emission properties of screen printed carbon nanotube (CNT) films, an Ar neutral beam was used as one of the surface treatment techniques and the CNT field emission characteristics after the treatment were compared with those after Ar ion beam treatment. The Ar neutral beam treatment enhanced the field emission properties of the CNTs and by decreasing the turn-on field and by increasing emission sites. When the field emission properties were measured after the treatment for 10 s with an energy of 100 eV, the turn-on field decreased from 1.7 to 0.9 V/μm while that after the ion beam treatment increased from 1.7 to 2.8 V/μm showing damage of exposed CNTs due to the intensive bombardment by the positive ions in the beam. The neutral beam treatment appeared to expose more CNT field emitters from the CNT paste without cutting or severely damaging the already exposed long CNT emitters because there were no charged particles in the beam.

Precise Depth Control and Low-Damage Atomic-Layer Etching of HfO[sub 2] using BCl[sub 3] and Ar Neutral Beam

The etch characteristics of HfO 2 by atomic-layer etching (ALET) were investigated using a BCl 3 /Ar neutral beam. The effect of ALET on surface modification and etch-depth control was also examined. Self-limited etching of HfO 2 could be obtained using BCl 3 ALET. This was attributed to the absorption of BCl 3 by the Langmuir isotherm during the absorption stage and the vaporization of hafnium-chlorides/boron oxychlorides formed on the surface during the desorption stage. In addition, the surface composition of HfO 2 was not altered by etching during ALET.

Formation of High Flux Parallel Neutral Beam Using a Three Grid System of Ion Beam during Low Angle Forward Reflection of Ions

The energy and the flux of the ion gun with a three-grid system was compared with those of the ion gun with a two-grid system and the characteristics of the neutral beam sources composed of the ion guns with different grid systems and a reflector for the low angle reflection of the ions were investigated. By using the three-grid system instead of the two-grid system and by applying higher negative voltage to the 2nd grid, a higher ion flux without changing the ion energy could be obtained for the ion gun of the neutral beam source. The three-grid ion gun system generated higher neutral beam fluxes compared to the two-grid ion gun system. This result was confirmed by measuring the etch rates of Si and GaAs with Ar and fluorine neutral beam. Also, using the neutral beam source with the three-grid ion gun, 35nm-width Si patterns could be etched vertically by CF4 gas indicating the formation of a parallel neutral beam.

The effect of Ar neutral beam treatment of screen-printed carbon nanotubes for enhanced field emission

This study examined the effectiveness of an Ar neutral beam as a surface treatment for improving the field emission properties of screen-printed carbon nanotubes (CNTs). A short period of the neutral beam treatment on tape-activated CNTs enhanced the emission properties of the CNTs, showing a decrease in the turn-on field and an increase in the number of emission sites. The neutral beam treatment appeared to render the CNT surfaces more actively by exposing more CNTs from the CNT paste without cutting or kinking the already exposed long CNT emitters. The treated CNTs emitted more electrons than the CNTs treated using other methods. When the field emission properties were measured after the neutral beam treatment, the turn-on field decreased from 1.65to0.60V∕μm and the emission field at 1mA∕cm2 decreased from 3.10to2.41V∕μm. After the neutral beam treatment for 10s, there was an improvement in the stability of the emission current at a constant electric field. It is expected that the neutral beam treatment introduced in this study will provide an easy way of improving the emission intensity and stability of screen-printed CNT emitters.

Surface Analysis of Atomic-Layer-Etched Silicon by Chlorine

Silicon atomic-layer etching (ALET) was carried out by the adsorption of Cl 2 to form silicon chlorides followed by the desorption of the silicon chlorides formed on the surface by irradiating an Ar neutral beam of a low energy. The silicon surface during the silicon ALET was investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy, and its etch mechanism was studied. XPS data showed that during the Cl 2 adsorption stage, silicon chloride bonding peaks related to SiCl and SiCl 3 were formed. The peak intensity related to SiCl bonding is slowly decreased during the desorption of silicon chlorides, and when the SiCl bondings are removed completely by irradiating enough Ar neutral-beam dose to the surface, the saturated silicon etch rate of 1.36 A/cycle which is related to one Si monolayer per cycle could be obtained. Also, at this condition, the surface roughness is close to the roughness of the silicon substrate itself. The SiCl bondings formed on the silicon surface during the adsorption stage are related to the desorption species during the ALET, while the SiCl 3 bondings are related to the species formed with the surface silicon damaged during the desorption stage.

Atomic Layer Etching of Silicon Using a Ar Neutral Beam of Low Energy

In this study, atomic layer etching of Si has been carried out using <TEX>$Cl_2$</TEX> adsorption followed by the irradiation Ar neutral beam of low energy. In this experiment, the etch rate of Si was dependent on the <TEX>$Cl_2$</TEX> pressure(the surface coverage of chlorine) and the irradiation time of Ar neutral beam(the flux density of Ar neural beam). And the etch rate of Si(100) and Si(111) were saturated exactly at one monolayer per cycle with <TEX>$1.36{\AA}/cycle\;and\;1.57{\AA}/cycle$</TEX>, respectively.

Atomic Layer Etching of Si(100) and Si(111) Using Cl[sub 2] and Ar Neutral Beam

Atomic Layer Etching of Si(100) and Si(111) Using Cl[sub 2] and Ar Neutral Beam

Surface Roughness Variation during Si Atomic Layer Etching by Chlorine Adsorption Followed by an Ar Neutral Beam Irradiation

Surface Roughness Variation during Si Atomic Layer Etching by Chlorine Adsorption Followed by an Ar Neutral Beam Irradiation

Analysis of Polyethyleneterephthalate Film Surface Sputtered with Ar Neutral and Ar Ion Beams

Polyethyleneterephthalate (PET) film surfaces sputtered with Ar neutral and Ar ion beams were investigated with scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). It was observed that the surface sputtered with the Ar neutral beam was flatter than that with the ion beam. AFM observation showed that the morphology size on the surface sputtered with Ar neutral beam was larger than that made by ion beam sputtering. XPS analysis showed that the decomposition of chemical bonding was reduced and the formation of amorphous carbon on the surface was suppressed when the surface was sputtered with the Ar neutral beam. The flattening mechanism could be clarified by AFM observation and XPS analysis. The sputtering process differs between the neutral beam and the ion beam with the same energy and dose.

Low‐energy Ar neutral beam etching method for x‐ray photoelectron spectroscopy

AbstractA simple Ar neutral beam gun capable of providing low‐energy Ar atoms has been developed for surface cleaning and depth profile analysis in x‐ray photoelectron spectroscopy, Auger electron spectroscopy, etc. Characterization of the Ar neutral beam gun is described. The effect of neutral beam bombardment was investigated for an Si(100) wafer and a polyethylene terephthalate (PET) film in order to reduce chemical damage by sputter etching in XPS. The neutral beam etching gun was composed of a Kaufman‐type ion source, a gas collision chamber and an electrostatic deflector. This gun can work also as an ion gun by a simple operation mode change. Neutral and ion beam fluxes were measured using an absorption current plate made of stainless steel. Experimental results showed that the probability of neutralization in a charge exchange chamber was ∼80% of the maximum between 1 x 10−1 Pa and 2 x 10−1 Pa, and the sputtering rate for SiO2 at 600 eV was 14 nm min−1, which is ∼30% lower than with a Kaufman‐type ion gun. The bombardment process for an Si wafer was essentially the same for the Ar ion beam and the Ar neutral beam. However, it was observed that radiation damage to the PET film surface etched by the neutral beam was remarkably diminished as compared with that by the ion etching method. This can be ascribed to the fact that the effect of electronic damage etching due to Ar0 is less than that due to Ar+.