Showing papers on "Focused ion beam published in 1986"

Focused ion beam induced deposition of gold

Abstract: A finely focused ion beam is scanned over a surface on which a local gas ambient of dimethyl gold hexafluoro acetylacetonate is created by a directed miniature nozzle. The incident ions induce the selective deposition of gold along the path traced by the beam. The 15‐keV Ga+ ion beam current is 100 pA and the beam diameter is 0.5 μm. Gold lines of 0.5 μm width and Gaussian profile are written. The film growth rate corresponds to five atoms deposited per incident ion. The focused ion beam deposited films contained 15% Ga, but less than 5% of other impurities, such as O or C. Deposition was also observed with broad ion beams of 750 eV Ar+ and 50 keV Si+. The resistivity of the films varied from 2×10−5 to 1.3×10−3 Ω cm.

Integrated circuit repair using focused ion beam milling

Abstract: A method of repairing short circuit defects in integrated circuits using a submicron focused ion beam is described. The technique is applicable to cutting conductive lines in fully processed wafers, whether or not they have been encapsulated. In a manner analogous to scanning electron microscopy, images of the integrated circuit features and defects are produced. Material is removed by slowly rastering the ion beam over the defect area, under computer control. Examples of focused ion beam repair applied during the testing phase of new chip designs are presented.

The focused ion beam as an integrated circuit restructuring tool

Abstract: One of the capabilities of focused ion beam systems is ion milling. The purpose of this work is to explore this capability as a tool for integrated circuit restructuring. Methods for cutting and joining conductors are needed. Two methods for joining conductors are demonstrated. The first consists of spinning nitrocellulose (a self‐developing resist) on the circuit, ion exposing an area, say, 7×7 μm, then milling a smaller via with sloping sidewalls through the first metal layer down to the second, e‐beam evaporating metal, and then dissolving the nitrocellulose to achieve liftoff. The resistance of these links between two metal levels varied from 1 to 7 Ω. The second, simpler method consists of milling a via with vertical sidewalls down to the lower metal layer, then reducing the milling scan to a smaller area in the center of this via, thereby redepositing the metal from the lower layer on the vertical sidewall. The short circuit thus achieved varied from 0.4 to 1.5 Ω for vias of dimensions 3×3 μm to 1×1 μm, respectively. The time to mill a 1×1 μm via with a 68 keV Ga+ beam, of 220 Pa current is 60 s. In a system optimized for this application, this milling time is expected to be reduced by a factor of at least 100. In addition, cuts have been made in 1‐μm‐thick Al films covered by 0.65 μm of SiO2. These cuts have resistances in excess of 20 MΩ. This method of circuit restructuring can work at dimensions a factor of 10 smaller than laser zapping and requires no special sites to be fabricated.

Lithographic approach for 100 nm fabrication by focused ion beam

Abstract: A bilevel resist process using P(SiSt90–CMS10) silicon containing resist as a top layer has been developed for Ga+ focused ion beam (FIB) lithography. A 100 nm linewidth pattern with 750 nm thickness has been demonstrated. Lithographic characteristics for 100 kV Ga+ FIB have been studied for PMMA positive resist and P(SiSt90–CMS10) negative resist. The results indicate that backscattering and proximity effects are negligible and that 100 kV Ga+ FIB resist sensitivity is about 100 times larger than that for 20 kV electron beam. Moreover, it has been observed that discontinuous lines, which may be caused by shot noise or by an oscillation at the end of the Taylor cone of Ga ion source, are produced at low dose for both PMMA and P(SiSt90–CMS10) resists.

Focused-ion-beam micromachined AlGaAs semiconductor laser mirrors

Abstract: A V-channel substrate inner stripe diode laser with conventional cleaved facet mirrors has been modified by micro-machining with a focused ion beam to produce a smooth machined output mirror with no change in its lasing threshold and only a small decrease in its external differential quantum efficiency.

Focused ion beam gallium implantation into silicon

Abstract: The electrical properties and lattice disorders of 50 keV, focused ion beam (FIB) gallium-implanted silicon layers have been investigated as a function of beam scan speed and ion dose. The critical dose for continuous amorphous layer formation is 8 ∼ 10 × 1013 ions/cm2, when the beam scan speed is lowered to about 10−2 cm/s. This is about 1/3 that of conventional ion implantation. The increase in secondary defect formation after annealing is also observed as the beam scan speed decreases under implantation conditions close to the critical dose. However, the effect of high dose rate on the electrical activation of gallium atoms and critical dose reduction is not as significant as with FIB implantation by a lighter ion mass, such as boron. The results are compared with those obtained by conventional ion implantation.

Integrated circuit diagnosis using focused ion beams

Abstract: The application of a focused ion beam to voltage‐contrast probing and repair of integrated circuits is demonstrated. Holes have been opened through passivation layers and waveforms have been acquired using voltage contrast. Voltage‐coding techniques have been used to trace signals and confirm repairs. A complementary metal‐oxide semiconductor (CMOS) programmable logic array (PLA) with a design error has been successfully repaired using ion beam milling to disconnect metal lines buried under thick passivation.

Manufacture of semiconductor device

Abstract: PURPOSE:To bury simply a through hole with electrode material according to the depth of the hole and to reduce surface step difference after the burying of the hole, by utilizing focused ion beam deposition in a process for burying the though hole with the electrode material. CONSTITUTION:Focused ion beam deposition is a method that can ionize material, that is, electrode material in a vacuum or under a low gas pressure, focus the ion beam with an electromagnetic lens and irradiate it selectively on a semiconductor substrate to be deposited. Since the focused ion beam deposition can freely alter energy focusing density and set selectively it, range, speed and thickness, etc., of electrode material deposition can be arbitrarily controlled. Accordingly, by applying the focused ion beam deposition, energy focusing density and irradiation time of the ion beam can be controlled to bury a through hole with electrode material flatly according to the depth and area of the hole.

Application of focused ion beam technology to maskless ion implantation in a molecular beam epitaxy grown GaAs or AlGaAs epitaxial layer for three‐dimensional pattern doping crystal growth

Abstract: We report on a new microfabrication process in UHV, implemented with a focused ion beam implanter (FIBI)–molecular beam epitaxy (MBE) crystal growth system with a computer controlled ion beam writing system. By using this combination process technology, GaAs/AlGaAs multilayer pattern doping structures are fabricated by iteration of growing a molecular beam epitaxy (MBE) GaAs or AlGaAs layer followed by implanting focused ion beams, arbitrarily choosing such impurity ions as Be ( p‐type) or Si (n‐type). This process technology is considered as a basis for integrating optical or electrical devices three dimensionally. An application of this technology to a new structure for an AlGaAs/GaAs DH laser is also described.

Characteristics of maskless ion beam assisted etching of silicon using focused ion beams

Abstract: Characteristics of ion beam assisted etching (IBAE) for Si have been investigated by bombarding focused ion beams (FIB’s) in Cl2 gas ambient. The etched surface was analyzed by Auger electron spectroscopy (AES). It was observed that the etching rate increased with increasing the Cl2 gas pressure at low gas pressure and decreased with further increase of the Cl2 introduction. It was also observed that the etching rate depends on the scan speed of the (FIB) and decreased rapidly at a high scan speed above 500 μm/s.

Ion beam processing of LiNbO3

Abstract: Ion implantation and ion beam mixing have been investigated as alternative techniques to hightemperature diffusion for introducing dopants into LiNbO3. Heavy ion bombardment at both 77 and 300 K initiated a near-surface decomposition causing Li to diffuse to the surface where it formed a nonuniform agglomerate. The damage and annealing characteristics of this effect were studied by ion scattering/channeling, secondary ion mass spectrometry, and optical microscopy. The origins of the surface decomposition are discussed along with possible solutions, and selected samples were evaluated for waveguide properties.

Using focused ion beam damage patterns to photoelectrochemically etch features in III-V materials

Abstract: A method of patterning n‐type GaAs, InP, InGaAs, and InGaAsP by photoelectrochemical (PEC) etching in conjunction with a submicron focused ion beam (FIB) at low dose is described. The ion beam is used to produce damage in a desired pattern in the material. Subsequent PEC etching of the material reveals the ion induced features in relief. The procedure is highly sensitive, requiring a dose of only 5×109 ions/cm2 for the differential etch to become apparent. The sensitivity allows rapid pattern generation in our FIB system.

Focused ion beam micromachining of optical surfaces in materials

Abstract: A method of forming one or more optical surfaces of the designer's choice in a body of material. The method includes the steps of exposing in a work zone a selected face in a body of selected material, directing a focused ion beam in a predetermined manner into the work zone to impinge the selected face, and by such directing and impinging, removing material from the body to create the desired optical surface(s). Preferably, beam direction is accomplished under the control of a suitably programmed computer.

Focused ion beam microsurgery for electronics

Abstract: Methods of making and breaking connections on an Al conductor test pattern using a focused ion beam (FIB) are demonstrated. Submicrometer dimension connections between crossing conductors separated by oxide were fabricated in 7 s. Resistances of the connections were measured to be 3 Ω and were tested up to 50 mA. Milled cuts in 0.65- µm-thick 10-µm-wide conductors produced open-circuit resistances > 20 MΩ in 300 s. The combined imaging, restructuring, and verification capability of FIB microsurgery is shown.

Ion beam lithography system

Abstract: When ions are implanted into desired locations on a material surface using a focused ion beam system, it is necessary to incline the direction of the implantation at about 7° to a line normal to the material surface. The system according to the present invention uses a deflector consisting of deflecting elements of two stages to deflect an ion beam, for effecting such an inclination. The beam is deflected in a given direction by the deflecting element of the first stage, and then it is deflected in the opposite direction by the deflecting element of the second stage. Since chromatic aberrations of the beam caused by the deflecting elements of the two stages cancel each other, defocusing of the beam on the material due to energy dispersion is suppressed.

Hybrid focused-flood ion beam system and method

Abstract: An ion beam microfabrication system is described which is capable of operating in either a flooded beam mode, in which a relatively high current beam is used to yield a rapid throughput, or in a low current, high resolution focused ion beam mode. With a focused beam a small, relatively low current ion spot is deflected in a predetermined pattern over a portion of the wafer to produce more detailed patterning that is not achievable in the flooded beam mode. A lens is added to the beam column to modify the beam collimation between the focused and flooded modes, and switching between modes is accomplished by simply actuating or de-actuating the lens. The beam is formed with a larger acceptance angle and total current in the flooded than the focused mode.

Fabrication of Index-Guided AlGaAs MQW Lasers by Selective Disordering Using Be Focused Ion Beam Implantation

Abstract: AlGaAs multiquantum well (MQW) lasers with buried optical guide (BOG) were fabricated using Be focused ion beam (FIB) implantation. The process is based on the effect wherein the compositional disordering of Si doped MQW is suppressed by Be ion implantation and subsequent annealing. The proposed process is very simple and does not require any lithographic procedure. It is confirmed that the fabricated laser acts as an index-guided laser. This technique is a promising new step toward optoelectronic integrated circuits.

CW operation of widely and continuously tunable micromachined-coupled-cavity diode lasers

Abstract: The CW operating characteristics of a two-section coupled-cavity diode laser formed by micromachining with a focused ion beam are described. Single-longitudinal-mode operation with discrete tunability over 30 A and continuous tunability over 2.8 A has been demonstrated.

A scanned microfocused neutral beam for use in secondary ion mass spectrometry

Abstract: The construction of a gun capable of producing a microfocused (FWHM=5 μm) beam of Ar atoms at 10 keV for use in secondary electron and SIMS imaging of insulating samples is described. The design is based on the principle of neutralizing an ion beam by charge transfer subsequent to rastering and microfocusing, and therefore utilizes a final focusing lens with long working distance (60 mm). Neutral beam intensities of up to 20% of the focused ion beam can be produced. The performance of the gun is illustrated by secondary‐electron and secondary‐ion images of insulators.

Micron Features In III-V Materials By Photoelectrochemical Etching Of Focused Ion Beam Induced Damage Patterns

Abstract: A method of patterning n-type GaAs, InP, InGaAs and InGaAsP by photoelectrochemical (PEC) etching in conjunction with a submicron focused gallium ion beam (FIB) at low dose is de-scribed. The ion beam is used to produce damage in a desired pattern on the material. Subsequent PEC etching of the material reveals the ion induc5d featurs in relief. The procedure is highly sensitive, requiring a dose of only 5x109 ions/cm2 (about 1 ion every 1500A) for the differential etch to become apparent. The sensitivity allows rapid pattern generation in our FIB system.

Secondary ion mass spectrometry system and method for focused ion beam with parallel ion detection

Abstract: A secondary ion mass spectrometry system and method is described which operates several orders of magnitude more quickly than previous systems, and captures information that might previously have been missed. A parallel detection approach is used which simultaneously monitors all secondary ion masses of interest, as opposed to prior serial approaches which sense only one ion mass at a time. The secondary ions are spatially separated according to mass and sensed by a detector array. An ion-electron converter and amplifier, implemented as a microchannel plate assembly, is preferably interfaced between the mass separator and detector. The detector preferably uses an array of wires to collect charge emitted by the microchannel plate. The wires are coupled to output lines by an encoding scheme which allows many fewer output lines to be employed than there are wires.

Ion implant apparatus

Abstract: An ion implant apparatus which forms ions from an ion source into an ion beam to implant the ions into a target to be ion-implanted through an ion beam introduction tube. The ion implant apparatus comprises: radiation means for radiating an electron beam, the radiating means fixed on the ion beam introduction tube; and a target for being radiated by an electron beam, said target reflecting the electron beam to generate a reflectance beam, the electron beam causing a secondary electron beam to be emitted from the electron beam target, the electron beam target being formed so as to prevent the reflectance beam and the secondary electron beam from being directly radiated on the target to be ion-implanted. The apparatus can keep high energy electrons from the surface of a wafer thereby to prevent the wafer from being charged negatively, and can trap the high energy electrons in the measuring system thereby to decrease errors in measuring a number of dopant atoms.

Ion emmissive head and ion beam irradiation device incorporating the same

Abstract: An ion emmisive head for fusing a metal to emit ion beam is disclosed, wherein a fused metal is designed to infiltrate through a porous portion for flow control and to reach an extremely sharpened needle which is provided after infiltration and wherefrom the fused metal is converted to ion beam by electrical action. Thus, ionized metallic beam is rendered to have smaller width or more focused ray. Submicron technology used in the IC industry, for instance, desires far thinner, finer beam line to attain more compact circuits, which need will be responded in the present invention by disposing a tipping needle to extend out of a porous tip portion which receives the fused metal from melting zone. Appropriate combination of sharpness at the needle point and provision of a beam guiding electrode in neighborhood of an emitting needle point enable to produce about 0.1 micron beam width by prevention of plasma ball which will otherwise diffuse the emitted beam.

Comparison of NPN transistors fabricated with broad beam and spatial profiling using focused beam ion implantation

Abstract: The base region of NPN transistors was fabricated using a 0.2 μm beam diameter (maskless) of 75 keV B focused ion beam (FIB), and on the same wafer a broad beam (with mask) of 75 keV B ions with conventional ion implantation. Transistor properties were compared using electrical characteristics, microbeam Rutherford backscattering spectroscopy (RBS), and scanning Auger microscopy (SAM). No significant differences were found between the transistors fabricated with FIB and with conventional ion implantation. Lateral doping profiles were implanted using the FIB system. Bipolar transistors with lateral active base profiles implanted with FIB were shown to have normal device characteristics. While the main intent was to assess the feasibility of fabricating the devices, the expected relationships between lateral profile and base resistance and current gain were observed. The results indicate that FIB can be used to study the impact of lateral profiles on device performance.