Electron Beam-induced Chemical Vapor Deposition Research Articles

Role of Activated Chemisorption in Gas-Mediated Electron Beam Induced Deposition

Models of adsorbate dissociation by energetic electrons are generalized to account for activated sticking and chemisorption, and used to simulate the rate kinetics of electron beam induced chemical vapor deposition (EBID). The model predicts a novel temperature dependence caused by thermal transitions from physisorbed to chemisorbed states that govern adsorbate coverage and EBID rates at elevated temperatures. We verify these results by experiments that also show how EBID can be used to deposit high purity materials and characterize the rates and energy barriers that govern adsorption.

Comparison of Young's Modulus Dependency on Beam Accelerating Voltage between Electron-Beam- and Focused Ion-Beam-Induced Chemical Vapor Deposition Pillars

We investigated Young's modulus of amorphous carbon (a-C) pillars that exhibited different properties depending on which of two fabrication methods were used, electron-beam-induced chemical vapor deposition (EB-CVD) or focused ion-beam-induced CVD (FIB-CVD). The Young's modulus of the FIB-CVD pillars was almost linearly proportional to the accelerating voltage, while that of the EB-CVD pillars showed a completely opposite results. Secondary electrons seemed to play an important role in the increase of Young's modulus of the pillars grown using EB-CVD.

Formation of iron silicide nano-islands on Si substrates by metal organic chemical vapor deposition under electron beams

Electron-beam induced chemical vapor deposition (EBI-CVD) of Fe(CO) 5 was performed on both Si (111) and (110) substrates at 673-873 K inside an ultrahigh vacuum transmission electron microscope. The formation of iron silicide islands was observed on both substrates. Cubic silicide nano-rods were formed on Si(111) substrates by EBI-CVD with focused electron beams. The formation of β-FeSi 2 islands was mainly observed on Si(110) substrates by EBI-CVD when the electron beam was broadly spread. It was shown that the size and the intensity of the electron beam played a significant role in EBI-CVD and affected the CVD process extensively.

Fabrication of Alpha-Iron and Iron Carbide Nanostructures by Electron-Beam Induced Chemical Vapor Deposition and Postdeposition Heat Treatment

We succeeded in fabricating crystalline alpha-iron nanostructures with desired shapes. Electron-beam-induced chemical vapor deposition with iron carbonyl gas, Fe(CO)5, was carried out at room temperature in a field-emission-gun scanning electron microscope to fabricate nanodots, nanorods and square frames. The as-deposited structures exhibited an amorphous phase containing iron, carbon and oxygen in their entire volumes and iron oxide nanocrystals existed near their surfaces. Postdeposition heat treatment at about 600°C resulted in the formation of crystalline alpha-iron and iron carbide phases in their structures, while maintaining their shapes. Quantitative elemental analyses using electron energy loss spectroscopy suggested that the original as-deposited iron-to-carbon compositional ratio is crucial in determining the stoichiometry of the produced structures after the heat treatment.

Growth Manner and Mechanical Characteristics of Amorphous Carbon Nanopillars Grown by Electron-Beam-Induced Chemical Vapor Deposition

We investigated the growth manner and mechanical characteristics of amorphous carbon (a-C) nanopillars formed by electron-beam-induced chemical vapor deposition (EB-CVD). The pillars' inclinations were well explained if we assumed the vertical growth rate to be almost constant within a specified distance from the substrate. The pillars' Young's modulus evaluated by deflection measurement was approximately 29 GPa, which was almost equivalent to that of bismuth, but much smaller than that observed in focused ion-beam-induced chemical vapor deposition (FIB-CVD) pillars.

Position-Controlled Carbon Fiber Growth Catalyzed Using Electron Beam-Induced Chemical Vapor Deposition Ferrocene Nanopillars

We demonstrated nanotube growth on a position-controlled catalyst using electron beam-induced chemical vapor deposition (EB-CVD) ferrocene nanopillars. While solid phase graphitization was induced at 650°C, iron nanoparticles only appeared on the surface by eroding the surrounding graphite triggered by the gas phase carbon fiber growth, at a temperature higher than 800°C using ethanol vapor. The precise position control achieved by EB-CVD directly reflected that of carbon fiber growth, which is a promising position-controlled carbon nanotube growth method for future device applications.

Position Controlled Growth in Carbon Nanotubes Catalyzed by an Iron Nano-dot Array

ABSTRACTWe report a successful demonstration of a position control technique for carbon nanotube growth catalyzed by an iron nano-dot array, which was fabricated by using electron beam induced chemical vapor deposition (EB-CVD). Point irradiation of an electron beam with ferrocene source gas produced an amorphous carbon dot containing iron atoms that were uniformly dispersed into each dot, and its position could be precisely controlled. Vacuum annealing of the ferrocene based dots induced segregation of iron nano-particles, whose size was almost proportional to the beam irradiation time. After removing the carbon residue, an ethanol CVD process carried out at 800°C under 40 mmHg of ethanol vapor induced carbon nanotube growth from the dots. Many grown nanotubes were very thin, being 0.7 to 1.8 nm in diameter. These diameters were much less than that of the bottom iron particles.

Nanostructures fabricated by electron beam induced chemical vapor deposition

Electron beam induced chemical vapor deposition (EBICVD) with tungsten and iron carbonyl gases, W(CO) 6 and Fe(CO) 5, was attempted to fabricate nanostructures. In case of the deposits from W(CO) 6 gas, the structure was a mixture of nanocrystals and amorphous phases and no change was seen after a post-deposition heating treatment. On the other hand, the deposits from Fe(CO) 5 gas were composed of amorphous iron surrounded by Fe oxide nanocrystals, and heating at about 600 ∘C resulted in the formation of crystalline Fe carbide and alpha-Fe phases. Thus, it was demonstrated that EBICVD with Fe(CO) 5 gas followed by a heating treatment can be used practically to fabricate nanostructures of magnetic materials.

Graphitized Wavy Traces of Iron Particles Observed in Amorphous Carbon Nano-pillars

We show evidence of solid-phase nanotube growth where traces of iron nano-particles were graphitized in an amorphous carbon nano-pillar fabricated by electron beam induced chemical vapor deposition (EB-CVD). The random walk of iron particles in the carbon nano-pillar caused continuous growth of wavy graphite tubes behind the iron particles as they moved during vacuum annealing at 800°C for 30 min. The graphite sheet in this solid-phase graphitization seemed to be produced at the tail of the iron nanoparticles, and some of the graphite tubes were multi-wall ones containing bamboo-joint-like cap sheets.

Electron induced nanodeposition of tungsten using field emission scanning and transmission electron microscopes

Electron beam induced chemical vapor deposition (EBI-CVD) is one of the promising methods for nanofabrication. EBI-CVD has generally been carried out in conventional scanning electron microscopes and the minimum size of the deposits was in the range between 20 and 300 nm. In this study, a field emission gun scanning electron microscope (FE-SEM) and a field emission gun transmission electron microscope (FE-TEM) with gas introduction systems were employed for deposition using a W(CO)6 precursor in order to reduce the size of deposits. Dots, 15–20 nm in diameter, were produced using the FE-SEM. The dots consist mainly of tungsten with small amounts of carbon and oxygen. By using the FE-TEM, the diameter of the dots can be reduced to 3.5 nm. The relationship between probe size and dot diameter is discussed. Rods, the diameter of which was 8 nm, were also fabricated by scanning the beam position in the FE-TEM. Deposits produced by FE-TEM are smaller than those by conventional electron microscopes.

Synthesis of Microcrystalline Silicon Films by Low Energy Electron-Beam-Induced Deposition at Cryogenic Temperature

ABSTRACTWe have proposed an advanced method for formation of semiconductor thin films at substrates temperatures below 100K. We have synthesized amorphous silicon (a-Si:H) and microcrystalline silicon (μc-Si:H) films using low-energy electron-beam-induced-chemical vapor deposition (EBICVD) onto cooled substrates which adsorb source gases (SiH4 or Si2H6) at cryogenic temperature. The temperature dependence on growth rate of the films, hydrogen content and optical constants were investigated. The μc-Si:H could be formed at 40–45 K on SiO2 using He-discharged-EBICVD with SiH4. The crystallinity of silicon was evaluated by Raman scattering spectroscopy and X-ray diffraction.

Carbon nanopillar laterally grown with electron beam-induced chemical vapor deposition

We found that the lateral growth of a carbon nanopillar with electron beam-induced chemical vapor deposition (EB-CVD) was mainly dominated by forward scattering of the electron beam. The minimum diameter of the carbon nanopillar was reduced to 5 nm. In contrast, vertical growth with EB-CVD produced thicker pillars ∼50 nm in diameter, with a shape that reflected forward scattering of the primary electrons. Graphitization of the amorphous carbon nanopillars was also demonstrated by annealing, in which nanoiron particle traces were graphitized.

In situ study of electron beam-induced chemical vapor deposition of Au in an environmental TEM

Patterning of metals is a key element in the fabrication of integrated microelectronics. For circuit repair and engineering changes constructive lithography, writing techniques, based on electron, ion or photon beam-induced decomposition of precursor molecule and its deposition on top of a structure have gained wide acceptance Recently, scanning probe techniques have been used for line drawing and wire growth of W on a silicon substrate for quantum effect devices. The kinetics of electron beam induced W deposition from WF6gas has been studied by adsorbing the gas on SiO2surface and measuring the growth in a TEM for various exposure times. Our environmental cell allows us to control not only electron exposure time but also the gas pressure flow and the temperature. We have studied the growth kinetics of Au Chemical vapor deposition (CVD),in situ, at different temperatures with/without the electron beam on highly clean Si surfaces in an environmental cell fitted inside a TEM column.