Showing papers on "Focused ion beam published in 1997"

Focused Ion Beam Milling and Micromanipulation Lift-Out for Site Specific Cross-Section Tem Specimen Preparation

Abstract: A site specific technique for cross-section transmission electron microscopy specimen preparation of difficult materials is presented. Focused ion beams are used to slice an electron transparent sliver of the specimen from a specific area of interest. Micromanipulation lift-out procedures are then used to transport the electron transparent specimen to a carbon coated copper grid for subsequent TEM analysis. The experimental procedures are described in detail and an example of the lift-out technique is presented.

Optimized time-of-flight secondary ion mass spectroscopy depth profiling with a dual beam technique

Abstract: High resolution depth profiling has been performed in a time-of-flight secondary ion mass spectroscopy (TOF-SIMS) instrument equipped with independent ion sources for sputtering (crater formation) and for SIMS analysis. In this dual beam mode a low energy sputter gun (Cs or any gas ion) allows a free selection of optimum sputter conditions with regard to depth resolution and matrix optimization. For secondary ion generation an independent high energy ion beam, optimized with regard to focussing and secondary ion yield (Ga or gas ion source) is applied. For different sputter gases (Ar, Xe, O2, and SF6), energies (0.3–2 keV) and angles of incidence a systematic investigation of B layers in Si and GaAlAs multilayers has been carried out. Decay lengths of 0.53 nm were achieved for low energy sputtering of B layers in Si with 0.6 keV SF5+. In this dual beam mode the depth profiling performance of TOF-SIMS exceeds that of state of the art quadrupole and magnetic sector field instruments in several fields of app...

Focused ion beam milling: Depth control for three-dimensional microfabrication

Abstract: Ion milling with a focused ion beam (FIB) is a potential method for making micromolds, which will then be the primary elements in the mass production of micro- or mini-objects by embossing or injection molding. The challenge lies in controlling the ion milling to produce cavities with predefined, arbitrary geometric cross-sections. This work involves programming variations as a function of position into the algorithm that generates the dwell times in the pixel address scheme of a FIB. These variations are done according to whether an axis of symmetry or a plane of symmetry determines the final geometry, and the result is 26 new cross-sectional shapes, such as hemispherical pits, parabolic pits, hemispherical domes, etc. The ion milling control programs were used to generate parabolic cross-section trenches, sinusoidal trenches, sinusoidal cross-section rings on an annulus, and hemispherical domes. We observed reasonable agreement between the shapes ion milled in Si(100) and the expected geometry. The dwel...

Writing FIB implantation and subsequent anisotropic wet chemical etching for fabrication of 3D structures in silicon

Abstract: The further miniaturization of silicon micromechanical structures in combination with the highly developed microelectronic technology at the micrometre and sub-micrometre level will lead to a new generation of microdevices. A modern technique to fabricate three-dimensional micromechanical structures is the combination of high-concentration p′ -doping by writing ion implantation using a focused ion beam (FIB) and subsequent anisotropic and selective wet chemical etching. FIB-patterned and chemically etched 3D Si structures with nanoscale thickness have been fabricated using 35 keV Ga + ion implantation and subsequent anisotropic etching in KOH/H 2 O solution. Design and fabrication considerations to achieve freestanding Si structures are discussed and some typical structures are shown.

Method and apparatus to improve the properties of ion beam deposited films in an ion beam sputtering system

Abstract: An ion beam sputtering system having a chamber and a target, a substrate, and a movable flux regulator located between the target and the substrate in the chamber. The position of the movable flux regulator relative to the deposition substrate affects the thickness uniformity of thin films deposited on the substrate in the ion beam sputtering system.

Focused ion beam sputter yield change as a function of scan speed

Abstract: In many of the applications of focused ion beams, such as integrated circuit sectioning and TEM sample preparation, considerable volume of materials may need to be removed. Thus optimizing the sputter yield is important. For very rapid scan speeds at normal incidence, each pass of the beam removes a thickness of material which is much smaller than the beam diameter. In this case, this milling yield corresponds to the yield at normal incidence. However, if the scan speed is slowed down so that the thickness removed per pass is comparable to the beam diameter, then locally under the beam the ions are not normally incident even though the beam is normal to the surface. The milling yield of Si and SiO2, for example, increases by a factor of seven to eight in going from normal incidence at 0° to 75°–85°. Thus the material removal rate can be significantly increased by reducing the scan speed. We have measured the milling yield of Si and SiO2 as a function of scan speed in one axis by milling boxes, typically 7...

Control of Aperture Size of Optical Probes for Scanning Near-Field Optical Microscopy Using Focused Ion Beam Technology

Abstract: We propose a fabrication technique for apertures of optical probes for scanning near-field optical microscopy (SNOM) using a focused ion beam (FIB) process. We tried two FIB processes, FIB drilling and FIB slicing. The FIB slicing technique is very useful for fabrication of nm-sized SNOM apertures of less than 50 nm. The problem with the FIB drilling process is that it is difficult to identify the apex of the tip and to control the beam onto the apex. The FIB slicing technique can easily fabricate an aperture at an apex and control aperture size by cut-off-depth. It is easy for a sharp tip to obtain accurate size of aperture. It can be considered to obtain accurate size of aperture with fabricated error of 35 nm in a sharp tip with cone angle of 30 deg.

Control mechanisms for dosimetry control in ion implantation systems

Abstract: A high throughput ion implantation system that rapidly and efficiently processes large quantities of flat panel displays. The ion implantation system has an ion source, an electrode assembly, a platform mounting a workpiece, and an ion beam measuring structure. The ion source in conjunction with the electrode assembly forms an ion beam in the shape of a ribbon beam. The ion beam is formed and directed such that a first portion of the ion beam treats the workpiece while a second portion of the ion beam is contemporaneously measured by the beam measuring structure. A controller obtains data from the beam measuring structure on the ion beam's parameters, and then generates control signals to the ion implantation system in response to the data.

Optimization of experimental operating parameters for very high resolution focused ion beam applications

Abstract: We report an experimental procedure to optimize the current profile of a focused ion beam probe, with a special emphasis on high resolution applications. The optimized operating conditions are given for three specific cases: specimen thinning for electron microscopy, nanoetching, and nanolithography. We present high quality membranes for transmission electron microscopy, arrays of nanoholes with reproducible dimensions of 17 nm etched on a nickel membrane, and finally nanolithography operations with a 10 nm resolution. Due to the conventional design of our focused ion beam system, the operating conditions that we have established for each nanofabrication application, should be successfully applied to a wide variety of ion columns.

Objective comparison of scanning ion and scanning electron microscope images

Abstract: Common and different aspects of scanning electron microscope (SEM) and scanning ion microscope (SIM) images are discussed from a viewpoint of interaction between ion or electron beams and specimens. The SIM images [mostly using 30 keV Ga focused ion beam (FIB)] are sensitive to the sample surface as well as to low-voltage SEM images. Reasons for the SIM images as follows: (1) no backscattered-electron excitation; (2) low yields of backscattered ions; and (3) short ion ranges of 20–40nm, being of the same order of escape depth of secondary electrons (SE) [=(3–5) times the SE mean free path]. Beam charging, channeling, contamination, and surface sputtering are also commented upon.

Focused ion beam assisted chemically etched mesas on GaAs(001) and the nature of subsequent molecular beam epitaxial growth

Abstract: Focused ion beam assisted chemical etching is examined as an ultrahigh vacuum compatible in situ direct-write approach to patterning substrates to create mesas with arbitrary shapes (i.e., sidewall angles) independent of crystallographic orientation. Ga+ ion beam assisted Cl2 etching of GaAs(001) is employed as a vehicle. A phenomenological model is used to predict mesa profiles as a function of ion beam conditions. Mesas created under various conditions are characterized via atomic force microscopy and good agreement is found between the measured and predicted profiles. Examination of the growth profile evolution on such mesas with as-patterned sidewall angles between ∼10° and ∼60° reveal that mesa top size reduction suitable for nanostructure fabrication on stripes oriented along the [110] and [100] directions occurs only for as-patterned mesa sidewall angles greater than ∼19° and ∼45°, respectively, which are the angles subtended by the {114} and {101} facets that emerge during growth and cause mesa t...

Photo mask and apparatus for repairing photo mask

Abstract: A method of repairing a defect existing on a photo mask comprising a transparent substrate and a mask pattern formed on the substrate, comprises steps of irradiating a focused ion beam toward the defect and supplying XeF2 gas to the defect, when an etching rate of the defect by the focused ion beam and XeF2 is 1.7 times greater than an etching rate by a sole irradiation of the focused ion beam.

Mode control in vertical-cavity surface-emitting lasers by post-processing using focused ion-beam etching

Abstract: Single-mode emission is achieved in previously multimode gain-guided vertical-cavity surface-emitting lasers (VCSEL's) by localized modification of the mirror reflectivity using focused ion-beam etching. Reflectivity engineering is also demonstrated to suppress transverse mode emission in an oxide-confined device, reducing the spectral width from 1.2 nm to less than 0.5 nm.

Recent advances of focused ion beam technology

Abstract: Recent advances of focused ion beam techniques are reviewed. These include ion implantation, ion beam assisted etching and deposition, and in situ fabrication. Owing to their maskless capability and high current density, focused ion beams found important applications as a tool for microsurgery for ULSI devices or material analysis, and in situ fabrication. Recent focused ion beam systems can produce focused ion beams with a diameter smaller than 10 nm and are of increasing importance also as nanofabrication tool. Various low dimensional structures have been fabricated using FIB mainly in GaAs GaAlAs heterostructure. For this application, FIB is used to define device structures by converting n-layers to semi-insulating layer or by forming active layers.

Sample evaluation/process observation system and method

Abstract: A sample evaluation/process observation system includes a common sample stage which accommodates a plurality of samples to be processed. The common sample stage is provided with a processing/observing notch and also with a movement mechanism. The movement mechanism functions to sequentially move the plurality of samples to the notch to cause the samples to be exposed to a predetermined processing beam and observing beam. The system further includes a beam processing device in which the common sample stage can be mounted and which functions to irradiate the predetermined processing beam on the plurality of samples through the notch to thereby sequentially perform beam processing operation over the samples. The system further includes a beam observation device in which the common sample stage can be mounted and which functions to irradiate the predetermined observing beam on the plurality of samples through the notch to sequentially observe and evaluate shapes of the plurality of samples. A mark is formed on one sample by a focused ion beam device so that positioning of the mark realizes automatic processing of a part of the sample to be processed. Further, the common sample stage is used in a high-acceleration transmission electron microscope and a high-acceleration scanning electron microscope and focused ion beam device.

Focused Ion Beams For Microfabrication

Abstract: Focused ion beam (FIB) techniques are commonly used in microelectronics for prototyping, failure analysis and process control. With the growing interest in MEMS (micro-electro-mechanical systems) the importance of FIB techniques in this field has to be established. For the FIB to be considered for production, the milling time is crucial. Using as an example the fabrication of a microaccelerometer structure the authors show there is scope for the FIB in the prototyping and production of micromechanical structures, leading to novel sensors.

High Resolution Structure Imaging of Octahedral Void Defects in As-Grown Czochralski Silicon.

Abstract: The crystal originated particles (COP's) as revealed by light scattering tools on Czochralski silicon wafer surfaces are investigated by means of high resolution transmission electron microscopy (HREM) on specimens prepared by a focused ion beam tool The structure imaging of buried defects gives direct evidence for the void nature of the defects leading to the formation of the COP's

Systems and methods for deposition of dielectric films

Abstract: The present invention provides systems and methods for the water-based deposition of silicon dioxide films. In one aspect, the invention provides methods for depositing a dielectric material to the surface of a workpiece. The workpiece can be, for example, an integrated circuit, a phase shift mask, or any other device that has features suitable for processing by a focused ion beam system. The method for depositing the dielectric material includes the steps of providing a chamber that has an interior portion with a stage element for holding the workpiece and that also includes an injection element for introducing reactant material into that interior portion, introducing through the injection elements a silicon-containing reactant material, introducing through the injection element a water-containing reactant material, and passing an ion beam through the interior portion and to the surface of the workpiece for depositing the dielectric material thereon. The process of the invention is suitable for focused ion beam induced deposition of a silicon dioxide film on top of an integrated circuit for forming an insulated layer or for depositing a silicon dioxide film on a phase shift mask for repairing a defect in the mask such as a bump or a void.

Focused ion beam nanolithography on AlF3 at a 10 nm scale

Abstract: We have investigated the potential use of AlF3 thin films (50 nm thick) as negative inorganic resist layers for focused ion beam nanolithography. We demonstrate that 10 nm-wide lines can be fabricated using a Ga+ beam of 30 keV incident energy. The resist sensitivity of 1010 Ga+/cm is two orders of magnitude lower than for polymethylmethacrylate organic resist. We emphasize that this low sensitivity associated with the exposure mechanism of the resist minimize the influence of the tails of the current distribution within the ion spot.

Low-energy focused-ion-beam exposure characteristics of an amorphous Se75Ge25 resist

Abstract: Ion-beam exposure and patterning characteristics of an amorphous Se75Ge25 thin film which acts as a positive resist in focused-ion-beam (FIB) lithography have been studied using low-energy Ga+ ion sources below 30 keV. The a-Se75Ge25 resist exposed to 10 keV defocused-Ga+ ion beam with the dose of 5.0×1014 to 9.3×1015 ions/cm2 results in increasing the optical absorption, which was also observed in the film exposed to an optical dose of 4.5×1020 photons/cm2. The absorption edge shift of 0.3 eV for the resist exposed to a dose of 9.3×1015 ions/cm2 at 10 keV is about twice that of photo exposure. These large shifts could be estimated as due to an increase in disorder, considering a decrease in the slope of the Urbach tail and a broad pattern of x-ray diffraction. For the exposure of a 30 keV Ga+ ion beam and above a dose of 1.4×1015 ions/cm2, a 590-A-thick resist film is completely etched by dipping for 10 s in 1:1:3 HNO3:HCl:H2O solution (25 °C), and then the etching rate is about 60 A/s. As the incident e...

Role of aberrations in high-current plasma lenses

Abstract: The influence of spherical and momentum aberrations on the focusing characteristics of intense ion beams in the electrostatic plasma lens (PL) is analyzed. The dependence of the ion beam focus on the uncompensated beam space charge and the finite azimuthal velocity at the PL exit is examined. Minimum focused beam radii are calculated for different system parameters and are shown to depend on the ion charge-to-mass ratio. The radial profiles of focused, multicharged, inhomogeneous ion beams were measured experimentally and compared with the theoretical predictions. We show that the PL, in principle, can be used for ion charge state analysis.

Fib repair method

Abstract: A method of repairing a defect on a substrate includes the steps of shining a beam, such as a focused ion beam, on a substrate to remove a portion of the defect and to leave a thin wall of the defect, and then providing a second removal step, such as an isotropic etch, to substantially remove the thin wall, wherein the second removal step comprises a process different from the original shining step.

Effects of focused ion beam irradiation on MOS transistors

Abstract: The effects of irradiation from a focused ion beam (FIB) system on MOS transistors are reported systematically for the first time. Three MOS transistor technologies, with 0.5, 1, and 3 /spl mu/m minimum feature sizes and with gate oxide thicknesses ranging from 11 to 50 nm, were analyzed. Significant shifts in transistor parameters (such as threshold voltage, transconductance, and mobility) were observed following irradiation with a 30 keV Ga/sup +/ focused ion beam with ion doses varying by over 5 orders of magnitude. The apparent damage mechanism (which involved the creation of interface traps, oxide trapped charge, or both) and extent of damage were different for each of the three technologies investigated.