Showing papers on "Ion implantation published in 1998"

Fabrication of single-crystal lithium niobate films by crystal ion slicing

Abstract: We report on the implementation of crystal ion slicing in lithium niobate (LiNbO3). Deep-ion implantation is used to create a buried sacrificial layer in single-crystal c-cut poled wafers of LiNbO3, inducing a large etch selectivity between the sacrificial layer and the rest of the sample. 9-μm-thick films of excellent quality are separated from the bulk and bonded to silicon and gallium arsenide substrates. These single-crystal films have the same room-temperature dielectric and pyroelectric characteristics, and ferroelectric transition temperature as single-crystal bulk. A stronger high-temperature pyroelectric response is found in the films.

Efficient production of silicon-on-insulator films by co-implantation of He+ with H+

Abstract: We have investigated the process of thin film separation by gas ion implantation and wafer bonding, as well as the more basic phenomenon of blistering, on which the technique is based. We show that when H and He gas implants are combined they produce a synergistic effect which enables thin-film separation at a much lower total implantation dose than that required for either H or He alone. By varying the H and He implantation doses we have been able to isolate the physical and chemical contributions of the gases to the blistering processes. We find that the essential role of H is to interact chemically with the implantation damage and create H-stabilized platelet-like defects, or microvoids. The efficiency of H in this action is linked to its effective lowering of the silicon internal surface energy. The second key component of the process is physical; it consists of diffusion of gas into the microvoids and gas expansion during annealing, which drives growth and the eventual intersection of the microvoids ...

Preparation of Titanium Oxide Photocatalysts Anchored on Porous Silica Glass by a Metal Ion-Implantation Method and Their Photocatalytic Reactivities for the Degradation of 2-Propanol Diluted in Water

Abstract: Highly dispersed titanium oxide photocatalysts anchored onto transparent plates of porous silica glass were successfully prepared by metal ion implantation, and their photocatalytic reactivity for ...

Metal nanoclusters in glasses as non-linear photonic materials

Abstract: Although electronics technologies have made great advances in device speed, optical devices can function in the time domain inaccessible to electronics. In the time domain less than 1 ps, optical devices have no competition. Photonic or optical devices are designed to switch and process light signals without converting them to electronic form. The major advantages that these devices offer are speed and preservation of bandwidth. The switching is accomplished through changes in refractive index of the material that are proportional to the light intensity. The third-order optical susceptibility, χ(3), known as the optical Kerr susceptibility which is related to the non-linear portion of the total refractive index, is the non-linearity which provides this particular feature. Future opportunities in photonic switching and information processing will depend critically on the development of improved photonic materials with enhanced Kerr susceptibilities, as these materials are still in a relatively early stage of development. Optically isotropic materials, e.g. glasses that have inversion symmetry, inherently possess some third-order optical non-linearities. Although this is quite small for silica-glasses at λ=1.06 μm, the absorption coefficient is extremely low, thereby allowing all-optical switching between two waveguides, embedded in a silica fibre, simply by controlling the optical pulse intensity. Different glass systems are now under investigation to increase their non-linearity by introducing a variety of modifiers into the glass-network. The incorporation of semiconductor microcrystallites enhances the third-order optical response. Metal colloids or nanoclusters, embedded in glasses, have also been found to introduce desired third-order optical non-linearities in the composite at wavelengths very close to that of the characteristic surface-plasmon resonance of the metal clusters. Ion implantation is nowadays an attractive method for inducing colloid formation at a high local concentration unattainable by the melt-glass fabrication process and for confining the non-linearities to specific patterned regions in a variety of host matrices. Recent works on metal-ion implanted colloid generation in bulk silica glasses have shown that these nanocluster–glass composites under favourable circumstances have significant enhancement of χ(3) with picosecond temporal responses. The remarkable achievements in developing such novel photonic materials seem to open the way for advances in all-optical switching devices, e.g. in inducing metal-colloids into coupled waveguides acting as a directional coupler. The present paper addresses the phenomena of optical non-linearities in metal nanocluster–glass composites that are synthesized by ion implantation, and the potential uses of these novel composite materials in photonics. © 1998 Chapman & Hall

Raman scattering in ion-implanted GaN

Abstract: Raman measurements were performed on molecular beam epitaxially grown GaN before and after implantation with Ar+, Mg+, P+, C+, and Ca+ ions. With increasing ion dose, new Raman peaks arise at 300, 360, 420, and 670 cm−1, independent of the ion species. After rapid thermal annealing at temperatures between 900 and 1150 °C for 15 s, the intensities of the Raman modes decrease with increasing temperature with the exception of the 360 cm−1 mode which shows a maximum in intensity after annealing at 900 °C. The mode at 300 cm−1 is attributed to disorder-activated Raman scattering, whereas the other three modes are assigned to local vibrations of vacancy-related defects.

A “smarter-cut” approach to low temperature silicon layer transfer

Abstract: Silicon wafers were first implanted at room temperature by B+ with 5.0×1012 to 5.0×1015 ions/ cm2 at 180 keV, and subsequently implanted by H2+ with 5.0×1016 ions/cm2 at an energy which locates the H-peak concentration in the silicon wafers at the same position as that of the implanted boron peak. Compared to the H-only implanted samples, the temperature for a B+H coimplanted silicon layer to split from its substrate after wafer bonding during a heat treatment for a given time is reduced significantly. Further reduction of the splitting temperature is accomplished by appropriate prebonding annealing of the B+H coimplanted wafers. Combination of these two effects allows the transfer of a silicon layer from a silicon wafer onto a severely thermally mismatched substrate such as quartz at a temperature as low as 200 °C.

Optical properties of silicon nanoclusters fabricated by ion implantation

Abstract: A method for the fabrication of luminescent Si nanoclusters in an amorphous SiO2 matrix by ion implantation is reported. We have measured the dose (concentration of excess Si atoms) and annealing time dependence of the photoluminescence of Si nanoclusters in SiO2 layers at room temperature. The samples were fabricated by ion implantation and subsequent annealing. After annealing, a photoluminescence band below 1.7 eV has been observed. The peak energy of the photoluminescence is found to be almost independent of annealing time, while the intensity of the luminescence increases as the annealing time increases. Moreover, we found that the peak energy of the luminescence is strongly affected by the dose of implanted Si ions, especially in the high-dose range. We also show direct evidence of widening of the band-gap energy of Si particles of a few nanometers in size by employing photoacoustic spectroscopy. These results indicate that the photons are absorbed by Si nanoclusters, for which the band-gap energy i...

Cathodic arc deposition of films

Abstract: ▪ Abstract Cathodic arc deposition is a plasma-based technology for the fabrication of films. The process can be carried out either at high vacuum or in a low pressure gaseous environment, and films can be formed for example of metals, ceramics, diamond-like carbon, some semiconductors and superconductors, and more. The plasma stream can be filtered to remove microdroplet contamination, and the ion energy can be controlled by substrate bias, thereby transforming the straightforward deposition method into hybrids with other surface modification processes such as ion beam–assisted deposition, ion beam mixing, and ion implantation. The method provides a versatile and powerful plasma tool for the synthesis of novel and technically important surfaces.

Ion implantation of semiconductors

Abstract: Ion implantation was first applied to semiconductors over 30 years ago as a means of introducing controllable concentrations of n- and p-type dopants at precise depths below the surface. It is now an indispensable process in the manufacture of integrated circuits. This review gives a brief and selected overview of ion beam modification of semiconductors, treating both fundamental and technological issues of current interest. Damage introduction during ion irradiation and its removal during a thermal annealing step are key issues which are highlighted. Some semiconductors are easily damaged and amorphised (e.g. silicon) whereas others (e.g. gallium nitride) are quite resistant to damage production due to efficient dynamic defect annihilation during implantation. The conditions needed to remove implantation damage also vary dramatically from one semiconductor to another: amorphous layers in silicon can be recrystallised to completely remove disorder at ∼600°C, whereas extended defects in gallium nitride require temperatures of >1400°C to remove them. High dose implantation can result in the formation of supersaturated solid solutions, alloys and compounds, often with intriguing properties as a result of the non-equilibrium aspects of ion implantation. Formation of silicon dioxide layers directly during oxygen bombardment of silicon, even under cryogenic implantation conditions, is given as an example. From the standpoint of semiconductor technology, there are several current issues under intense study. Two of these are highlighted with respect to silicon technology: the problems of transient enhanced diffusion of dopants during low temperature annealing due to residual implantation-induced defects, and the need to remove extremely low concentrations of metals from active device regions. Finally, some recent novel applications of implantation in compound semiconductors are treated.

Ion-beam induced damage and annealing behaviour in SiC

Abstract: The paper presents the damage accumulation in silicon carbide (SiC) as a function of the ion mass, the ion energy and the implantation temperature. A defect-interaction and amorphization model is used to analyse the dose dependence of defect production, as obtained by the various methods. The temperature dependence of the amorphization dose can be represented assuming a thermally enhanced annealing within the primary collision cascades. On the basis of such a model, a critical implantation temperature is obtained, which was found to vary with the ion mass and the implantation energy. The concurrent influence of implantation temperature and ion fluence on the resulting damage distribution in SiC is demonstrated. The damage annealing of ion implanted SiC is investigated for low, medium and high damage concentrations. The effect of the implantation temperature and the concentration of implanted atoms, both influencing the kind of defects obtained after implantation, on the annealing behaviour is analysed.

Semiconductor substrate manufacturing method

Abstract: The invention provides a number of semiconductor substrate manufacturing methods with which, in manufacturing a semiconductor substrate having a semiconductor layer in an insulated state on a supporting substrate, it is possible to obtain a thick semiconductor layer with a simple process and cheaply while reducing impurity contamination of the semiconductor layer to a minimum. One of these methods includes a defective layer forming step of carrying out ion implantation to a predetermined depth from the surface of a base substrate to partition off a monocrystalline thin film layer at the surface of the base substrate by a defective layer formed by implanted ions, a semiconductor film forming step of forming a monocrystalline semiconductor film of a predetermined thickness on the monocrystalline thin film layer, a laminating step of laminating the base substrate by the surface of the monocrystalline semiconductor film to the supporting substrate, and a detaching step of detaching the base substrate laminated to the supporting substrate at the defective layer.

Method for making a thin film of solid material

Abstract: The invention concerns a method for making a thin film of solid material, comprising the following steps: a step of ion implantation through a surface of said solid material substrate by means of ions capable of producing, in the substrate volume and at a depth close to the mean penetration of the ions, a layer of microcavities or microbubbles, said step being carried out at a predetermined temperature and for a predetermined duration; an annealing step for bringing the layer of microcavities or microbubbles to a predetermined temperature and for a predetermined duration to obtain a cleavage on either side of the layer of microcavities or microbubbles. The annealing step is carried out with a predetermined thermal budget, based on the thermal budget of the ion implantation step and optionally on other thermal budgets induced by other steps, to obtain said cleavage of the substrate.

Red shift of plasmon resonance frequency due to the interacting Ag nanoparticles embedded in single crystal SiO2 by implantation

Abstract: A metal nanoparticle system has been prepared by 200 Kev Ag+ ion implantation into perfect single crystal SiO2 at room temperature to dose: 6.7×1016/cm2. The system presents quasidual-layer structure: the shallower implanted layer containing noninteracting small Ag nanoparticles and the deeper layer containing interacting large nanoparticles, in which great red shift, about 1 eV, comparing with the plasmon resonance frequency of the noninteracting nanoparticle, can be clearly observed. The red shift is attributed to the multipoles interaction among the high density nanoparticles at external electric field. Moreover, the magnitude of red shift increases with implanted dose.

Handbook of surface and interface analysis : methods for problem-solving

Abstract: Elements of problem-solving how to use this book spectroscopic and spectrometric techniques - x-ray photoelectron spectroscopy (ISS) compositional analysis by Auger electron and x-ray photoelectron spectroscopy ion beam techniques - surface mass spectrometry in-depth analysis - methods for depth profiling ion beam effects in thin surface films and interfaces surface modification by ion implantation introduction to scanned probe microscopy metallurgy microelectronics and semiconductors minerals, ceramics and glasses composites corrosion and surface analysis - an approach involving spectroscopic and electrochemical methods problem-solving methods in tribology with surface specific techniques catalyst characterization adhesion science and technology archaeomaterials appendices - physical constants and conversion factors, data for the elements and isotopes, less commonly used techniques for analysis of surfaces and interfaces, core-level binding energies, Auger kinetic energies and modified Auger parameters for some chemical elements in various compounds, documentary standards in surface analysis - the way of the future?.

Photonic integrated circuits fabricated using ion implantation

Abstract: Intermixing the wells and barriers of quantum-well (QW) laser heterostructures generally results in an increase in the bandgap energy and is accompanied by changes in the refractive index. A technique, based on ion implantation-induced QW intermixing, has been developed to enhance the quantum-well intermixing (QWI) rate in selected areas of a wafer. Such processes offer the prospect of a powerful and simple fabrication route for the integration of discrete optoelectronic devices and for forming photonic integrated circuits.

Atomic nitrogen in C60:N@C60

Abstract: (atomic nitrogen inside C60) is produced by ion implantation. Two different production methods are employed: Kaufman ion source and glow discharge. After the bombarded material is dissolved in toluene or CS2 and is filtered, several milligrams of C60 containing N@C60 in a concentration of 10-4 to 10-5 are obtained. N@C60 gives a very clear hyperfine-split electron paramagnetic resonance signal. The most prominent features of N@C60 are: (i) Nitrogen in C60 keeps its atomic electronic configuration and occupies the on-center position. (ii) N@C60 is stable at ambient conditions, the thermal instability starts at 260 °C. (iii) The complex survives exohedral addition reactions and is a sensitive detector of cage distortions caused by addends. (iv) C60 and N@C60 exhibit slightly different retention times in column chromatography, thus permitting an enrichment of N@C60 by this method.

Ion implantation as a tool in the synthesis of practical third-order nonlinear optical materials

Abstract: It is now well-established that metal nanocrystal composites with attractive third-order non-linear optical properties can be synthesized in various dielectric hosts by ion implantation, ion exchange, sol–gel processes, sputtering, and pulsed-laser deposition. Whether these are appropriate to make practical all-optical switching and wave-guiding devices remains to be seen; however; in particular, techniques for the fabrication of simple device structures based on these materials are largely unexplored. This paper reviews the optical physics of the third-order non-linearity in metal nanocrystal composites, to illustrate how material parameters of both quantum dots and host matrix affect the optical non-linearities. The figures of merit that characterize simple building blocks—such as wave-guide resonators and directional couplers—for all-optical switching circuits are discussed. Novel ways of using ion implantation to enhance the properties of layered nanocluster and nanocrystalline materials are considered, particularly those that complement techniques for building up optical heterostructures, such as ion exchange, sputtering and pulsed-laser deposition.

Effect of fluorine on the diffusion of boron in ion implanted Si

Abstract: Ion implants of 1 keV 11B+ and 5 keV BF2+, to a dose of 1×1015/cm2 at a tilt angle of 0°, were implanted into preamorphized (Si+,70 keV, 1×1015/cm2) wafers. These samples were rapid thermal annealed in an ambient of 33 ppm of oxygen in N2 at very short times (<0.1 s spike anneals) at 1000 and 1050 °C to investigate the effects of the fluorine in BF2 implants on transient enhanced diffusion (TED). By using a relatively deep preamorphization of 1450 A, any difference in damage between the typically amorphizing BF2 implants and the nonamorphizing B implants is eliminated because the entire profile (<800 A after annealing) is well contained within the amorphous layer. Upon annealing, the backflow of interstitials from the end-of-range damage from the preamorphization implant produces TED of the B in the regrown layer. This allows the chemical effect of the fluorine on the TED of the B in the regrown Si to be studied independent of the damage. The secondary ion mass spectroscopy results show that upon annealin...

Dopant activation and surface morphology of ion implanted 4H- and 6H-silicon carbide

Abstract: The activation of ion-implanted B into 4H-SiC, and B, and Al into 6H-SiC is investigated. Complete activation of B implants into 4H-SiC is achieved by annealing at 1750°C for 40 min in an Ar environment. Significant activation (>10%) is not achieved unless the annealing temperature is 1600°C or greater. Sheet resistances of Al-implanted 6H-SiC annealed at 1800°C are 32.2 kΩ/□, indicating high activation of Al at this temperature. Annealing conditions which result in good acceptor activation are shown to be damaging to the surface of either 4H- or 6H-SiC. Atomic force microscopy and Nomarski differential interference contrast optical microscopy are applied to characterize the surfaces of these polytypes. Roughening of the surfaces is observed following annealing in Ar, with measured roughnesses as large as 10.1 nm for B-implanted 4H-SiC annealed at 1700°C for 40 min. Based on data obtained from these techniques, a model is proposed to describe the roughening phenomenon. The premise of the model is that SiC sublimation and mobile molecules enable the surface to reconfigure itself into an equilibrium form.

Streaming metal plasma generation by vacuum arc plasma guns

Abstract: We have developed several different embodiments of repetitively pulsed vacuum arc metal plasma gun, including miniature versions, multicathode versions that can produce up to 18 different metal plasma species between which one can switch, and a compact high-duty cycle well-cooled version, as well as a larger dc gun. Plasma guns of this kind can be incorporated into a vacuum arc ion source for the production of high-energy metal ion beams, or used as a plasma source for thin film formation and for metal plasma immersion ion implantation and deposition. The source can also be viewed as a low-energy metal ion source with ion drift velocity in the range 20–200 eV depending on the metal species used. Here we describe the plasma sources that we have developed, the properties of the plasma generated, and summarize their performance and limitations.

Transfer of patterned ion-cut silicon layers

Abstract: The technique of transferring patterned ion-cut layers from one Si wafer to another was demonstrated. The starting silicon wafer was masked with checkerboard and line patterns with a 3 μm thick polymethylmethacrylate/photoresist and was implanted with 5×1016 H+ ions/cm2 at 150 keV. After stripping off the mask, the wafer was bonded to an oxide-coated receptor wafer through low-temperature direct wafer bonding. Heat treatment of this bonded pair showed that the hydrogen-induced silicon surface layer cleavage (ion cut) could propagate throughout about 16 μm×16 μm of nonimplanted material with implanted regions only 4 μm wide. Mask width, spacing, and implantation profiles through the mask shape were shown to have effects on the internal microfracturing mechanisms.

{311} defects in silicon: The source of the loops

Abstract: The annealing kinetics of extended defects in Si+-implanted Si have been investigated by in situ annealing plan-view transmission electron microscopy (TEM) samples in a TEM. A 〈100〉 Czochralski-grown silicon wafer was implanted with 100 keV Si+ at the subamorphizing dose of 2×1014 cm−2. Following implantation, the effect of annealing of 800 °C was studied by in situ annealing. After 5 min of annealing at 800 °C, a dense collection of both {311} defects (3×1011/cm2) and small subthreshold dislocation loops (1×1011/cm2) were observed. Upon subsequent annealing, the {311} defect density decreased rapidly and the loop density increased. The evolution of approximately 500 {311} defects could be followed as a function of annealing time. The unfaulting of a {311} defect was observed to be the source of every subthreshold loop observed to from (about 150 loops in the monitored region). After the initial 5 min anneal at 800 °C, the probability of a {311} unfaulting into a loop was about 50%. Based on these observa...

Room-temperature photoluminescence from Tb ions implanted in SiO2 on Si

Abstract: The room-temperature photoluminescence (PL) of Tb3+ ions has been studied. The Tb ions were implanted into 200 nm thick SiO2 on Si wafers. To achieve a uniform Tb distribution, the implantations were performed at 50, 100, and 190 keV to a total dose of 8.8×1014–1.3×1016 ions/cm2, resulting in Tb concentrations of 0.18–2.7 at. %. The PL spectrum consists of sharp lines due to the Tb3+ intra-4f transitions and a broadband due to SiO2 defects. The samples were annealed at temperatures ranging from 600 to 1050 °C. Up to 900 °C, the annealing procedure improves the PL yield; at temperatures higher than 1000 °C, the PL yield drops again at high dose. The PL spectra show noticeable influence of Tb–Tb crossrelaxation, which favors the green PL over the blue PL.

Method of fabricating an integrated circuit having punch-through suppression

Abstract: An integrated circuit and method of fabrication is provided for an integrated circuit having punch-through suppression. Unlike conventional methods of punch-through suppression wherein a dopant implant is fabricated in the device, the present invention utilizes an inert ion implantation process whereby inert ions are implanted through a fabricated gate structure on the semiconductor substrate to form a region of inert ion implant between source and drain regions of a device on the integrated circuit. This accumulation region prevents punch-through between source and drain regions of the device. In a second embodiment, the inert ion implantation is used in conjunction with the conventional punch-through dopant implant. In this second embodiment, diffusion of the implant during subsequent thermal annealing is suppressed by the inert ion accumulation in the subsurface region of the device. Accordingly, improved integrated circuits and methods of fabricating an integrated circuit having punch-through suppression are disclosed.

Method for forming a silicide region on a silicon body

Abstract: The invented method produces a silicide region on a silicon body that is useful for a variety of purposes, including the reduction of the electrical contact resistance to the silicon body or an integrated electronic device formed thereon. The invented method includes a step of producing an amorphous region on the silicon body using ion implantation, for example, a step of forming a metal layer such as titanium, cobalt or nickel in contact with the amorphous region, and a step of irradiating the metal with intense light from a source such as a laser, to cause metal atoms to diffuse into the amorphous region to form an alloy region with a silicide composition. In an application of the invented method to the manufacture of a MISFET device, the metal layer is preferably formed with a thickness that is at least sufficient to produce a stoichiometric proportion of metal and silicon atoms in the amorphous region of the gate of the MISFET device. Importantly, the irradiating step proceeds until the metal overlying the gate alloy region is consumed and the gate alloy region is exposed. The gate alloy region has a higher reflectivity than the metal layer, and thus reduces further thermal loading of the gate alloy region so that silicide growth can be continued in the source and drain regions without adversely impacting the gate of the MISFET device. The invention also includes an integrated MISFET device in which the gate silicide region is greater than the source/drain silicide region.