Showing papers on "Focused ion beam published in 1984"

Ion Beam Assisted Deposition of Metal Organic Films Using Focused Ion Beams

Abstract: 50 keV Ar+ or focused Au+ were irradiated in a trimethyl aluminum atmosphere to investigate characteristics of ion beam assisted deposition. About 80 nm thick films were deposited at a dose of 1×1016/cm2. The film composition and its depth dependence was measured by Auger electron spectroscopy. It was found that the film contains oxygen, carbon and aluminum, and the atomic ratio varies across the film depth. The atomic ratio was 0.8(O):1.1 (C):1.4(Al) at the surface and was 0.8(O):3.3(C):1(Al) inside. A direct maskless pattern deposition was also done using 50 keV focused ion beams.

Deposition of diamondlike carbon films

Abstract: A diamondlike carbon film is deposited in the surface of a substrate by exposing the surface to an argon ion beam containing a hydrocarbon. The current density in the ion beam is low during initial deposition of the film. Subsequent to this initial low current condition, the ion beam is increased to full power. At the same time a second argon ion beam is directed toward the surface of the substrate. The second ion beam has an energy level much greater than that of the ion beam containing the hydrocarbon. This addition of energy to the system increases mobility of the condensing atoms and serves to remove lesser bound atoms.

Ion plasma electron gun

Abstract: An ion plasma electron gun for the generation of large area electron beams with uniform electron distribution. Positive ions generated by a wire in a plasma discharge chamber are accelerated through an extraction grid into a second chamber containing a high voltage cold cathode. These positive ions bombard a surface of the cathode causing the cathode to emit secondary electrons which form an electron beam. After passing through the extraction grid and the plasma discharge chamber, the electron beam exits from the gun by way of a second grid and a foil window supported on the second grid. The gun is constructed so that the electron beam passing through the foil window has a relatively large area and a uniform electron distribution which is substantially the same as the ion distribution of the ion beam impinging upon the cathode. Control of the generated electron beam is achieved by applying a control voltage between the wire and the grounded housing of the plasma chamber to control the density of positive ions bombarding the cathode.

Target study for heavy ion beam fusion

Abstract: Heavy ion beam driven implosion of multilayered, single-shell targets for inertial confinement fusion are investigated by ID-simulation. Features characteristic of heavy ion energy deposition are studied. The ion beam energy and the tamper/absorber configuration which give optimum hydrodynamic efficiency and fuel ignition are found for a reactor-size target. A comparison of different pulse shapes with and without prepulse is presented. Implosion by a single-box pulse is found to give superior hydrodynamic efficiency and spherical stability. In addition to these specific results, general features of ion driven implosions are discussed and a brief description of the target code MINIHY is given.

Beam scanning control device for ion implantation system

Abstract: In an ion implantation system wherein an ion beam is scanned by deflection means in a predetermined direction on substrates placed on a disc rotating at a constant speed, to implant the substrates with ions; ion beam detectors are arranged in correspondence with a plurality of places of the substrate before the ion implantation. When the ion beam is scanned, sums of outputs of the respective ion beam detectors in the plurality of scanning positions are evaluated, and correction operations are executed so that they may become constant values. The scanning rate of the ion beam by the deflection means is controlled according to the corrections. Thus, when the ion beam is actually implanted into the substrate, the density of the ion beam becomes uniform.

Ion implantation, ion beam mixing, and annealing studies of metals in Al2O3, SiC and Si3N4☆

Abstract: Ion scattering/channeling, TEM, EPR and optical microscopy are utilized to determine the structural modifications of ion implanted and annealed Al2O3, SiC, and Si3N4, and to correlate these modifications to surface mechanical property measurements. Ion beam mixing is also studied for inducing increased adherence of metal films on these insulators.

Hall ion generator for working surfaces with a low energy high intensity ion beam

Abstract: Apparatus and method for generating low energy, high intensity ion beams. A Hall current ion source is provided to conduct many integrated circuit fabrication processes which require low energy ion bombardment such as surface cleaning. Ion sources are provided which have tapered magnetic pole pieces for controlling the dispersion pattern of the ion beam.

Electron beam control assembly for a scanning electron beam computed tomography scanner

Abstract: An improved ion clearing electrode assembly for use in an electron beam production and control assembly which is especially suitable for use in a scanning electron beam computed tomography X-ray scanning system. The assembly uses a vacuum sealed housing chamber which is evacuated of internal gases and in which the electron beam is generated and propagated. Normally residual gas within the chamber interacts with the electrons of the beam to produce positive ions which have the affect of neutralizing the space charge of the electron beam and thereby causing focusing difficulties and destabilization of the beam. The ion collecting electrodes herein are an improvement of those disclosed in the co-pending Rand U.S. patent application Ser. No. 434,252, now U.S. Pat. No. 4,521,900. The electrodes are designed to extract the ions and reduce their neutralizing effect while maintaining a precisely uniform electric field and therefore beam optical aberrations are minimized. In addition, the electrode provides flexibility in the variation of parameters which effect ion extraction and the neutralization fraction.

Dry development of resists exposed to low‐energy focused gallium ion beam

Abstract: This paper proposes a new lithography method employing focused ion beam exposure and subsequent dry development. It is shown that the O2 plasma etching or reactive ion etching rate for resists exposed to gallium ions is much lower than that for resists not exposed. A comparison is made between plasma development and reactive ion development. An improvement in the resist sensitivity and contrast value γ using a CF4+O2 mixture gas for reactive ion development is discussed. It is possible to fabricate 0.5‐μm‐width lines and spaces in 0.6‐μm‐thick PMMA film at 1×10−4‐C/cm2 gallium ion exposure.

High Dose Rate Effect of Focused-Ion-Beam Boron Implantation into Silicon

Abstract: The effect of high-dose-rate, 16 keV focused-ion-beam (FIB) B+ implantation into Si has been investigated as a function of current density and beam-scan speed. It is shown by µ-RHEED (micro-probe reflection high-energy electron diffraction) observation that the increase in electrical activation of implanted B atoms at such low temperature annealing as 600°C closely correlated with the increase in amorphous zones produced. It is also found that continuous amorphous layer formation occurs with a 1–2×1015 ions/cm2 (one order lower than for conventional implantation) when both implantation conditions of high current density and slow scan speed (e.g. 20 mA/cm2 and 6×10-3 cm/s) are satisfied. The reason for amorphous zone formation enhancement by FIB implantation is discussed.

30 nm Line Fabrication on PMMA Resist by Fine Focused Be Ion Beam

Abstract: A 30 nm line pattern with 0.4 µm depth was successfully fabricated on a PMMA resist by a 100 kV focused Be++ beam emitted from Au–Si–Be ternary alloy ion source. The line width fabricated decreased with the decrease in ion dose.

Focused ion beam column

Abstract: Two lens focused ion beam column (10) has an accelerating lens (20) which carries a potential to focus a nonmagnified image of the liquid metal ion source (14) on the mass analyzer slit (26). Munro lens (36) accelerates the beam of selected ion species and demagnifies the image to provide an ion writing spot of less than about 1000 Ao size.

Ton beam neutralizer

Abstract: A method and apparatus for converting an ion beam from a standard ion gun into a neutral particle beam by the processes of resonance neutralization followed by Auger deexcitation and/or Auger neutralization, established by directing the ion beam to pass in the proximity of a suitable metal surface.

Ion implantation apparatus and method for maskless processing

Abstract: This invention relates to an ion implantation apparatus and method for maskless processing of substrate, and more particularly, to form ion implanted pattern by selectively scanning a focused ion beam on the surface of a processing substrate. The timing of the apparatus is controlled by a variable frequency clock pulse. By using the variable frequency oscillator, a clock frequency can be controlled continuously. So, the ion implantation pattern is easily controlled by the clock frequency and scanning number with high accuracy compared to a prior art.

Characteristics of Ion Beam Assisted Etching of GaAs Using Focused Ion Beam: Dependence on Gas Pressure

Abstract: Characteristics of maskless ion beam assisted etching of GaAs have been investigated. A focused Ga beam was irradiated on GaAs in a chlorine atmosphere. It was observed that this etching technique gives a higher etching rate than physical sputter etching without chlorine gas. The etching rate exhibited a maximum at a gas pressure of about 20 mTorr and decreased above that. By the present technique, 0.3 µm wide, 3 µm deep U-shaped grooves were formed on GaAs surface, while by physical sputter etching the grooves were V-shaped and narrow due to redeposition and/or self focusing effect.

An Application Of Focused Ion Beams To Electron Beam Testing Of Integrated Circuits

Abstract: One of the applications of high current density, focused ion beams (FIB) that has been made possible by the advent of the liquid metal ion source (LMIS) is milling of micron sized structures. In this study we examine the prospect of using a FIB system to selectively remove the passivation layer from IC's in order to carry out quantitative voltage contrast measurements on the conductors thus exposed.

Si MOSFET Fabrication Using Focused Ion Beams

Abstract: Si MOSFET fabrication using focused ion beamsR.L. Kubena, J.Y. Lee, R.A. Juliens, R.G. Brault,P.L. Middleton, and E.H. StevensHughes Research Laboratories, Malibu, California 90265AbstractSubmicrometer focused ion beams have been used both for the maskless ion implantationof p- channel depletion -mode Si MOSFETs and for the gate lithography of n- channelenhancement -mode Si MOSFETs. B -Pt and Au -Si liquid -metal -alloy ion sources were utilizedin a single -lens focusing column for the implantation and lithography steps, respectively.An 800 -A -thick Al stopping layer was used at the target to separate the lighter ions fromthe heavier ion species in the beams. Reasonable dc electrical characteristics weremeasured for the chosen device process parameters.IntroductionFocused -ion -beam technology offers new possibilities for novel device processes andis rapidly becoming a viable method for advanced microfabrication. Features such asselective implantation doping, high resolution sputtering, and low- proximity -effectlithography with high resist sensitivities are attractive for future VLSI circuitfabrication. Recently, selective implantation doping of GaAs at ultrahigh dose rates withfocused Si and Be beams has been demonstrated (1,2). Moreover, by using a Au -Si -Beeutectic -alloy ion source, alternate submicrometer lines of n- and p -type regions in GaAscan be easily implanted (3). In addition, the unique feature of high resolution sputter-ing (4) made possible by tiny ion beams has been utilized for X -ray mask repair (5).Focused ion beams have also been used successfully for high resolution lithographicprocesses by exposing polymer (2) and inorganic (6) resist layers and by enhancing theetch rate of substrates in a reactive atmosphere (7). As a lithographic tool, focused ionbeams provide several distinct advantages over electron beams. First, ions undergo lessscattering in resist layers and less backscattering from thick substrates. Therefore,proximity effects are minimized. Second, the energy loss per unit thickness of resist ismuch higher for ions than for electrons, and therefore, resist sensitivities are enhanced.Third, material modification is possible with ion exposures, and these modifications cansubsequently inhibit or enhance etch rates. Thus, focused -ion -beam technology providesincreased versatility for lithographic processes.This paper describes the use of focused ion beams for both implantation and gatelithography in Si FET fabrication. A single electrostatic -lens focusing column (8) withunity magnification was used for all experiments. Focused -ion -beam techniques aredescribed, and dc electrical characteristics of the resulting devices are presented.Maskless ImplantationFor the maskless ion implantation of Si FETs, a 90 -kV B -Pt beam was used forselectively doping p -type regions in n -type (100) Si. Typical spot diameters and targetcurrents were 2000 A and 0.1 x 10 -9 A, respectively. An 800 -A -thick Al stopping layer atthe target was used to trap the Pt ions. Using the range statistics of Gibbons et al.(9), we estimated that less than 0.01% of the Pt ions entered the underlying substrateduring implantation, while more than 90% of the dopant ions passed through the Al layer.Crosses etched in the Si substrate served as benchmarks for focused- ion -beamregistration for the FET doping. Registration was performed in a manner similar to thatreported previously (1). Following registration, the beam was programmed to raster scanthree overlapping rectangular patterns for source, drain, and channel implants. The chan-nel region was first doped to a fluence of roughly 6 x 1011 /cm2 by scanning a 40- x 50 -umpattern. Next, two 18- x 50 -um patterns were scanned on the outer edges of the channelimplant to serve as source and drain contact areas, thereby leaving 4 um between thecontacts for gate fabrication. The beam dwell time was adjusted before contact implan-tation so that all contact regions received a total B fluence of 2 x 1014/cm2. A 140 x180 -um capacitance -voltage (C -V) test pattern also was implanted to the same fluence thatwas used for the FET channel implant.Following focused- ion -beam doping, the Pt -doped Al layer was removed and the waferwas annealed. After annealing, a 380 -A -thick gate oxide layer was grown on the wafer.Source /drain contact windows were opened in the gate oxide layer by plasma etching and Al

Ion microbeam implanting apparatus

Abstract: An ion microbeam implanting apparatus is composed of an ion source (1), a beam focusing system for effecting acceleration, focusing, mass separation and deflection of ions emitted from the ion source (1), and a sample table (3) for affecting very fine movement of a sample. For the ion mass separation effected in the beam focusing system, a Wiener filter (4) is employed in which uniform electric and magnetic fields are made orthogonal to each other. A linear optical axis is bent in the Wiener filter (4) such that the beam axis of ions emitted from the ion source and the beam axis of ions to be implanted into the sample intersect each other.

Bi-Level Structures for Focused Ion Beam Using Maskless Ion Etching

Abstract: This paper proposes a bi-level structure for a maskless ion etching using focused ion beam. The bi-level structure can be realized by using a new phenomenon, wherein the Ga+ doped AZ1450J bottom layer is etched off by a high dose of more than 0.76 µC/cm. A Si top layer with 70 nm linewidth is fabricated. The linewidth can be controlled to nanometer dimensions by changing the dose. Moreover, fine structures with 100 nm are demonstrated using bi-level structures for the substrate etching and lift-off processes.

Method for disconnecting interconnection using focused ion beam

Abstract: A method of disconnecting an interconnection (43) using a focused ion beam. A portion to be disconnected of an interconnection formed on a semiconductor substrate (41) to connect semiconductor elements formed in the substrate is aligned with an ion beam irradiating location, and a focused ion beam generated from a focused ion beam source is irradiated onto the interconnection to etch the interconnection by sputtering so that the interconnection is disconnected.

Method for maskless ion implantation

Abstract: This invention relates to an ion implantation apparatus and method for maskless processing of substrate (12), and more particularly, to form ion implanted pattern by selectively scanning a focused ion beam on the surface of a processing substrate (12). The timing of the apparatus is controlled by a variable frequency clock pulse. By using the variable frequency oscillator (25), a clock frequency can be controlled continuously. So, the ion implantation pattern is easily controlled by the clock frequency and scanning number with high accuracy compared to prior art.

Field emission ion beam generator

Abstract: PURPOSE:To secure a high current ion beam in a field emission ion beam generator wherein an emitter tip is supplied with a liquid metal by conducting a mass separation of an ion beam by a Wien Filter. CONSTITUTION:When gallium is used as a liquid metal 3, H2 gas is supplied from a gas supply equipment 9, the partial pressure of the H2 gas is obtained by a flow control valve 8, and an ion extracting voltage is applied between a ion extracting electrode 5 and an emitter tip 1, the ion beam of H is obtained in a stable state with the ion beam of Ga . Similarly, when the partial pressure gases of O2 and N2 are supplied, ion beam currents due to the ion beams of O and N are produced. These ion beam currents are more than three orders in magnitude larger than the ion beam current due to the ion beam obtained by a field separation. Therefore, only the ion beams of H , O , and N can be extracted by the mass separation of an ion beam 6 by means of a Wien filter or by a sector magnetic field.