Showing papers on "Focused ion beam published in 1988"

The Electron Beam Ion Trap: A New Instrument for Atomic Physics Measurements

Abstract: An electron beam ion trap has been built for the production of very-highly-charged ions and the study of their collisions with electrons. A high density electron beam is used to trap, ionize and excite the ions for spectroscopic measurements. X-ray spectra from neon-like Ba46+ are reported and a theory of "evaporative" cooling is developed to explain why these ions are retained in the trap for surprisingly long times.

Integrated optical waveguides in polyimide for wafer scale integration

Abstract: Optical interconnections promise several key advantages over their electrical counterparts such as large bandwidth and reduced propagation delay. The limitations of electrical interconnections become even more significant for wafer scale integration (WSI), and wafer scale hybrid packaging (WSHP) because of the length of wafer scale interconnections. The authors investigate the possibility of using optically transparent organic dielectrics such as certain polyimides as waveguide materials for integrated optical waveguides, and the use of a focused ion beam (FIB) for micromachining optical structures such as mirrors. >

Ion beaming irradiating apparatus including ion neutralizer

Abstract: In an ion beam irradiating apparatus for providing a neutralized ion beam to a sample, there are provided an ion source, an accelerating device and an ion beam selecting device to which the accelerated and selection ion beam is irradiated This irradiating apparatus further includes an ion neutralizer positioned between the selecting device and the sample, and includes: an electron beam emitting source for emitting an electron beam; a first electron scatter preventing electrode for preventing the electron beam emitted from the electron beam emitting source from being scattered outside the ion neutralizer; a second electron scatter preventing electrode for preventing the electron beam induced into the specified ion beam from being scattered in a direction opposite to an ion irradiating direction; and a control electrode for controlling a traveling velocity of the electron beam emitted from the electron emitting source so as to drift the emitted electron beam toward the sample, thereby neutralizing the selected ion beam at a location adjacent to a surface of the sample that is being irradiated

A variable energy focused ion beam system for in situ microfabrication

Abstract: The combination of molecular‐beam epitaxy with focused ion beam (FIB) technology offers the opportunity for generating true three‐dimensional ultrasubmicron structures. One problem, however, is that conventional FIB systems employ landing energies of ∼50 keV and up, and so the spatial extent of damage by the beam, exceeds both the radius of the beam and the thickness of layers frequently grown. We have investigated focusing of beams of ions of energies down to 25 eV by employing retarding field optics. Modeling of the optics indicates that space charge becomes serious at currents above 1 nA for Ga+ ions of 50‐eV energy but that submicron beams of such ions are possible at lower currents. An experimental column was built and largely confirmed the predictions. Beam diameters were measured to be within a factor of 2 of the predicted value with a value of 0.95 μm for a 1‐nA beam of Ga+ ions of landing energy of 25 eV.

Ion beams for materials analysis

Abstract: The contents of this book are: Concepts and Principles of Ion Beam Analysis; Overview of Techniques and Equipment; High Energy Ion Scattering Spectrometry; Nuclear Reactions. Ion Induced X-Ray Emission; Channeling; Depth Profiling of Surface Layers During Ion Bombardment; Low Energy Ion Scattering from Surfaces and Interfaces; Microprobe Analysis; and Critical Assessment of Analysis Capabilities.

Method and apparatus for modifying patterned film

Abstract: Apparatus for modifying a patterned film, composed of an ion source for producing an ion beam which is focused and caused to impinge upon a sample to microscopically machine a small region upon the surface of the sample; scanning electrodes and a scanning control cirucit for scanning the focused ion beam; a detector that detects the secondary charged particles emanating from the sample in response to the irradiation; and a display device for displaying the pattern formed upon the sample according to the output from the detector. The apparatus further includes a nozzle for spraying etching gas against only a certain portion of the pattern when the focused ion beam is caused to fall upon the certain portion of the pattern, the gas being activated by the ion beam and capable of etching the material of the film upon which the pattern is formed. The focused ion beam that irradiates and scans the sample is not permitted to move from one spot to a neighboring spot until a given period of time elapses. Thus, a desired portion of the patterned film is rapidly and cleanly removed while minimizing the amount of the etching gas admitted into the apparatus.

High-resolution focused ion beam lithography

Abstract: The resolution of focused ion beam (FIB) lithography has been studied by proximity effect measurement and fine pattern fabrication. In the proximity effect measurement, a 0.1 μm line pattern, according to the gap between square and line patterns, could be achieved. Moreover, 0.1 μm line and space poly(methylmethacrylate) patterns and 0.1 μm linewidth novolak based negative resist could be fabricated at 1×1013 and 2×1012 ions/cm2 dose by 260 keV Be++ FIB with 0.1 μm beam diameter, respectively.

Sputter deposition for multi-component thin films

Abstract: Ion beam sputter-induced deposition using a single ion beam and a multicomponent target is capable of reproducibly producing thin films of arbitrary composition, including those which are close to stoichiometry. Using a quartz crystal deposition monitor and a computer controlled, well-focused ion beam, this sputter-deposition approach is capable of producing metal oxide superconductors and semiconductors of the superlattice type such as GaAs-AlGaAs as well as layered metal/oxide/semiconductor/superconductor structures. By programming the dwell time for each target according to the known sputtering yield and desired layer thickness for each material, it is possible to deposit composite films from a well-controlled sub-monolayer up to thicknesses determined only by the available deposition time. In one embodiment, an ion beam is sequentially directed via a set of X-Y electrostatic deflection plates onto three or more different element or compound targets which are constituents of the desired film. In another embodiment, the ion beam is directed through an aperture in the deposition plate and is displaced under computer control to provide a high degree of control over the deposited layer. In yet another embodiment, a single fixed ion beam is directed onto a plurality of sputter targets in a sequential manner where the targets are each moved in alignment with the beam under computer control in forming a multilayer thin film. This controlled sputter-deposition approach may also be used with laser and electron beams.

Fabrication of one-dimensional GaAs wires by focused ion beam implantation

Abstract: Novel, simple techniques were developed to fabricate very narrow GaAs conducting wires by utilizing direct focused ion beam (FIB) implantation. We employed two methods for fabrication of the wires. The first method makes use of high‐resistivity (HR) regions formed by FIB implantation without successive annealing to define a very narrow conducting wire (HR method). In the second one, focused Si ions are line implanted into p‐type GaAs, forming an n‐type conducting wire in the p‐type region. Then, reverse‐bias is applied across the pn junction in order to make the wire narrower by expanding the depletion layer (PN method). This structure has an advantage that the thickness of the wire can be varied by bias voltage. Magnetoconductances measured in all the fabricated wires show evidences of weak electron localization and conductance fluctuations due to a quantum interference effect. The minimum widths of the wires are evaluated to be ∼20 nm (HR method) and ∼100 nm (PN method) by fitting the theory of one‐dime...

Further Evaluation of the High Intensity Plasma Sputter Heavy Negative Ion Source

Abstract: In this report, we provide more detailed information on the high intensity heavy negative ion source described previously. Intensity vs time spectra, mass distribution data and source operational data are presented for Au, Cu, Ni and CuO sputter probes. Sputter probe voltage limited beam intensities of 10.2, 8.2, 5.1 and 4.5 mA, respectively have been realized from these sputter probes. The results of emittance measurements for Au and Ni probes indicate a rather strong dependence on beam intensity, as expected from space charge considerations. The source, when operated in pulsed mode, holds considerable promise for use in conjunction with tandem electrostatic accelerator/synchrotron injection applications. The high intensity capabilities of the source make it a viable candidate for generating mA intensity level, cw ion beams for a variety of other applications, including ion implantation.

A 0-30 keV low-energy focused ion beam system

Abstract: Low‐energy focused ion beam (FIB) is a useful tool for shallow doping, gas‐assisted etching, and other uses to minimize substrate damage in semiconductor device fabrication. The possibility to form a finely FIB of low energy under 1 keV was suggested in the investigations on the retarding mode in electron optical systems. The abilities of the simplest type of retarding mode FIB column are examined here. The optical properties are calculated for the corresponding model and some images are observed with Ga+ ion beams <0.3 μm in diameter for beam energies, 10, 5, and 1 keV, using a retarding mode one‐lens FIB system. 1‐keV and 100‐eV Ga+ FIB was implanted to Ga/As substrate, and the defects are analyzed by deep‐level transient spectroscopy. The defect concentration for 100 eV was < (1)/(5) that for 1000 keV.

Focused‐ion‐beam milling, scanning‐electron microscopy, and focused‐droplet deposition in a single microcircuit surgery tool

Abstract: Inspection by microtomography of active devices, tuning, and repair of III–V microstructures and microcircuits have been performed using the capabilities of combined scanning‐electron microscope (SEM) and low‐voltage (0.5–20 kV) focused‐ion‐beam (FIB), or focused‐droplet beam (FDB) system. In this instrument, the ion or dropletbeams are focused simultaneously on the same point of the sample as the electron beam. I n s i t u(SEM) images of the region to be machined or coated are displayed before, during, and after erosion or metal deposition. Gallium and indiumFIB probes of 10 to 20 kV were used to cut functional parts of devices such as heterojunction bipolar transistors or field‐effect transistors. Strong chemical contrast in the SEM mode displays very distinctly the different levels of the structure. This constitutes a promising method for fast nondestructive on‐line control testing of a given device. Cuts of electrical connections have been realized. Surface resistance effects induced by the ion impact have been observed. Accurate resistor adjustment has been realized by FIBmilling and controlled by i n s i t u monitoring of the resistance.Indium and gold dropletbeams have been focused on GaAs substrates. Best emission and focusing conditions have been determined giving deposited domains smaller than the structures previously obtained. Conducting connections have been fabricated by scanning the FDB and monitored by i n s i t u recording the resistance during the establishment of the conducting bridges.

Quantitative analysis by submicron secondary ion mass spectrometry

Abstract: In order to apply secondary ion mass spectrometry (SIMS) to quantitative analysis of submicron areas, we made a high‐spatial resolution SIMS (submicron SIMS) by combining a focused metal ion beam, a plane‐focusing mass spectrometer, and a multichannel parallel detection system. A 35 kV, 100 pA beam with diameter on the sample of <0.1 μm was used. During measurements, this high‐current density ion beam can destroy the sample with a large sputtering rate when slowly rastered. This causes rapid changes in both absolute and relative intensities of secondary ions. In our system, a 120‐channel parallel detector covers the 1:2 mass range of m/e dispersion. By using this submicron SIMS, quantitative factors in the analysis of microstructures on the surface were investigated. Sputtering yield and, consequently, secondary ion intensity depend largely upon the angle between the primary beam and the sample surface just under the beam irradiation; such topographic effects distort the quantitative results. In order to ...

Focused ion beam induced deposition of opaque carbon films

Abstract: A one‐step process for the repair of micron and submicron sized clear defects in photomasks is described. Opaque films are deposited at the intersection of the flux of organic monomers from a gas jet and a focused Ga ion beam. Focused ion beam induced deposition differs from other ion‐induced, electron beam, and laser processes due to the very high ion current density, and the sputtering of the material as it is being deposited. We have explored the deposition–sputtering rate competition for several precursor materials as a function of gas jet pressure (molecular flux) and ion beam dose rate (scanning conditions). The deposition rate for our process is linear with ion dose at 330 A per 1017 ions/cm2 and independent of dose rate over a wide range of conditions. The deposited films are cross‐linked polymers containing as much as 25 at. % Ga, adhere to either Cr or glass, and are chemically inert. Scanning slit microdensitometry measurements show a white‐light extinction coefficient of 2.2×10−3 A−1. As a res...

Quantitative analysis of resolution and stability in nanometer electron beam lithography

Abstract: A technique for the measurement of the beam diameter and the positional stability of an electron beam with respect to the substrate using an anisotropically etched silicon edge is described. Measurements are done either in a scanning beam mode to measure the beam diameter or in a stationary beam mode to measure beam positional noise. This technique has been used for a quantitative analysis of the resolution and stability in a 8‐nm spot size electron beam lithography system. The detection limit of the beam position stability measurements is <0.1 nm. Applications for the measurement of mechanical vibrations and acoustical noise, deflection amplifier noise, magnetic interference, and eddy currents in magnetic deflection systems are discussed.

Transverse thermal velocity broadening of focused beams from liquid metal ion sources

Abstract: Experiments have shown that the target current density in focused ion beam columns have long ‘‘tails’’ outside the central submicron region. We show that these tails result from a transverse velocity distribution which has a Holtsmark probability density. Both theory and experiment show that the tails are reduced as the system magnification and source current are reduced.

Device having superlattice structure, and method of and apparatus for manufacturing the same

Abstract: An ion beam (113) focused into a diameter of at most 0.1 µm bombards substantially perpendicularly to the superlattice layers of a one-dimensional superlattice structure and is scanned rectilinearly in a direction of the superlattice layers so as to form at least two parallel grooves (108, 109, 110, 111) or at least two parallel impurity-implanted parts (2109) as potential barrier layers, whereby a device of two-dimensional superlattice structure can be manufactured. At least two parallel grooves (114, 115, 116, 117) or impurity-implanted parts are further formed orthogonally to the potential barrier layers of the two-dimensional superlattice structure, whereby a device of three-dimensional superlattice structure can be manufactured. In addition, deposition parts (2403, 2404, 2405) may well be provided by further depositing an insulator into the grooves (108, 109, 110, 111, 114, 115, 116, 117) which are formed by the scanning of the ion beam. Owing to these expedients, the portions of the two-dimensional and three-dimensional super­lattice structures can be manufactured with ease and at high precision.

Ultrathin semiconductor layer masks for high vacuum focused Ga ion beam lithography

Abstract: The application of thin semiconductor layers as etch masks for high vacuum lithography is described. Heteroepitaxial layers of In0.53Ga0.47As or InP, as thin as 30 A, were grown by molecular beam epitaxy and patterned using a focused beam of Ga ions. The Ga ion beam exposure is very rapid, since only a small amount of the mask material needs to be removed, and readily produces features with submicron sizes. The patterned thin layer can then be used as a mask for deep, material selective etching. The feasibility of selective dry etching of InP based compounds is discussed. This combination of molecular beam epitaxy and efficient precision patterning techniques is expected to result in a new flexibility in design and fabrication of semiconductor devices.

Analog-to-digital converter made with focused ion beam technology

Abstract: An analog-to-digital converter (10) employs a series of comparators (12, 14, 16 and 18). Each comparator includes at least one inverter consisting of a CMOS transistor pair including a P-channel transistor (22) and N-channel transistor (24). The threshold levels of the transistors (22, 24) are modified using focused ion beam implantation techniques to provide the comparators with monotonically increasing transition levels.

Method and apparatus for correcting defects of x-ray mask

Abstract: The present invention relates to method and apparatus for correcting defects of an X-ray mask comprising the steps of: irradiating a focused ion beam to at least a region having a defective portion of an X-ray mask (200) having a protective film (204, 304) and eliminating the protective film; exposing a circuit pattern (205, 305) having a defective portion (150, 160) locating under the region or setting this circuit pattern to the state near the exposure; detecting at least one of the secondary electrons, secondary ions, reflected electrons, and absorbing current generated from that region and detecting a true defective position; positioning the focused ion beam to the true defective position and irradiating the focused ion beam to the defective portion; and thereby correcting the defect.

Favorable source material in liquid‐metal‐ion sources for focused beam applications

Abstract: The variety of ion species is increased by using alloys as well as pure elements as the source material of liquid‐metal‐ion sources (LMIS’s) in focused‐ion‐beam (FIB) technology. Some experiments show that the base elements of the alloy affect the charge and energy distributions of emitted ions. Doubly charged ions, which have a narrower energy spread per charge and smaller energy tail than the singly charged ions, form a finer FIB. The intensity ratio of doubly to singly charged ions is expected to increase with selection of an alloy with higher surface tension, because this will strengthen the electric field at the ion emitting surface. LMIS characteristics in connection with source materials are discussed.

Dot lithography for zero-dimensional quantum wells using focused ion beams

Abstract: A 50‐keV focused Ga+ beam formed in a two‐lens microprobe column with prefinal lens deflection was used to expose dot arrays in a negative‐acting bilevel resist. Dot arrays 600×600 μm with 600‐A‐diam resist posts on 0.6‐μm centers (incorporating 1024×1024 dots) were fabricated with ion exposure times of 18 s (beam dwell times of 16 μs/post). By reducing the beam dwell time by a factor of 2, roughly 300‐A‐diam posts were fabricated. Since the ions stop in the bottom resist layer and do not enter the substrate, the optical properties of underlying material should not be altered by damage from the exposure process.

Defects induced by focused ion beam implantation in GaAs

Abstract: The characteristics of defects induced by Si and Ga focused ion beam (FIB) implantation in n‐GaAs have been investigated by means of deep‐level transient spectroscopy (DLTS), C–V carrier profiling, and resistance measurements. The DLTS spectra of Si and Ga FIB implanted samples annealed at temperatures up to 500 °C are apparently identical to one another and show three different electron traps with an activation energy between 0.25 and 0.6 eV. The resistance increases by more than five orders of magnitude by Si and Ga FIB implantation due to the induced defects. However, it is restored to initial values after annealing at 600 °C, except for a sample of Ga implantation with a dose higher than 1014 /cm2 . For annealing of induced defects, there are no intrinsic problems for FIB implantation with a dose lower than 1013 /cm2 .

Focused ion beam processes for high‐Tc superconductors

Abstract: Focused ion beam (FIB) processes have been developed for Y–Ba–Cu–O superconductor films. A Y–Cu liquid metal ion source has been fabricated, using a Y67 –Cu33 eutectic alloy as the ion source. As‐sputtered Y–Ba–Cu–O film etch rate ratios to GaAs(100) and Si(100) substrates are 0.28 and 1.4 for 130‐keV Au+ FIB ion etching, respectively. Y–Ba–Cu–O submicron patterns have been demonstrated by using FIB lithography and Cl2 reactive ion beam etching. Moreover, a Y–Ba–Cu–O superconducting line with 4‐μm linewidth has been fabricated by annealing an as‐sputtered Y–Ba–Cu–O line pattern. Tc control of Y–Ba–Cu–O film has been achieved by 200‐keV Ne+, using conventional ion implantation and 300 keV Si++ FIB ion implantation.

Observation of microfabricated patterns by scanning tunneling microscopy

Abstract: A small‐size scanning tunnel microscope (STM) developed to provide an easy operation for both tip and sample setting is applied to three‐dimensional topographic measurements of microlithography patterns. The patterns having a grid structure with 160 nm in periodicity, 20–30 nm in groove width, and 40–50 nm in groove depth are fabricated on Si substrates using a technique of enhanced chemical etching by focused ion beam. The STM images are compared with two‐dimensional scanning electron microscope images. Fairly good resolution of topographic maps for a large area is obtained for the fine groove structures. The large‐area images are further processed to correct the piezoscanners’ nonlinearity, which becomes conspicuous for large‐area scanning.

GaAs/AlGaAs material modifications induced by focused Ga ion beam implantation

Abstract: Two aspects of the material property modifications of the GaAs/AlGaAs system induced by Ga focused ion beam implantation have been studied. One is the formation of a highly resistive region in an n‐type GaAs layer, and the other is the enhanced interdiffusion of GaAs/AlGaAs heterointerfaces. Both modifications enable us to change material properties with a minimum dimension of <100 nm. Quantum‐well‐wire structures were successfully fabricated by using the latter technique.

Imaging microanalysis of surfaces with a focused gallium probe

Abstract: A focused gallium scanning ion probe is used, in conjunction with an efficient secondary ion mass spectrometry system, to obtain high lateral resolution mass‐resolved images of specimen surfaces. The Ga+ beam, extracted from a liquid metal ion source, is accelerated to 40 keV and focused to a spot with a minimum diameter of ∼20 nm (ultimate resolution). The secondary ion handling system is briefly discussed; the secondary ion detection efficiency is 0.2%. Applications relevant to integrated circuit inspection and evaluation are presented, including high signal statistics elemental images of the metallizations and substrate of submicrometer devices, and examples of the detection of circuit flaws.

Semiconductor integrated circuit device, method of making same or cutting method for same, and cutting system using energy beam for same

Abstract: In making defect correction and circuit change in a semiconductor integrated circuit device using a focused ion beam etching technique, the present invention relates to an IC or VLSI structure having a trial cutting region, a test etching region and an auxiliary wiring or pad, suitable for the application of such defect correction and circuit change, as well as a method of making same, a designing method using such technique, and a focused ion beam system and other systems for use in those methods.