bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser Stimulated Deposition of GaAs, GaAsP and GaAsP-GaAs Superlattices
Authors: Karam N. H. , Bedair S. M. , El-Masry N. A. , Griffis D. 
Published: March 2011

AbstractAn Ar+ ion laser has been used for direct writing of GaAs and GaAsP single crystal films on thermally biased GaAs substrates. Multiple scanning of the laser beam at speeds in the range 100–200 μm/s at carefully selected growth conditions resulted in single crystalline selectively deposited films. Photoluminescence indicates that these deposited films have optical properties that are comparable with the conventionally (MOCVD) grown material.
Laser beam irradiation has been used to form a superlattice (SL) structure which has been demonstrated in the GaAsP-GaAs system. When a GaAs substrate is exposed to fluxes of AsH3, PH3 and TMG at 500°C, only GaAs will be deposited because of the insufficient cracking of PH3. However, localized laser heating results in GaAsP deposition. A GaAsP-GaAs superlattice with a period of about 400 Å has been synthesized. This laser induced technique can thus have potential applications in the generation of abrupt interfaces without the use of shutters as in MBE or gas switching as in MOCVD.
Real-Time Studies of Laser Oxidation of Copper: Characteristics of an Optical Heat Source
Authors: Baufay L. , Houle F. A. , Wilson R. J. 
Published: March 2011

AbstractOxidation of copper films is carried out using a cw argon ion laser. Time-resolved reflectance measurements during the reaction are performed at probe wavelengths of 632.8 and 514.5 nm. Strong temporal variations in reflectance are observed, and are attributed to interference within the growing oxide film. Measurements carried out as a function of laser power are complemented by Auger electron and scanning electron microscopy. A theoretical model of the system has been developed which treats its optical and thermal properties and the film growth process in an integrated way. The calculations highlight the intimate connection between the time dependence of the optical properties of the metal-metal oxide system and the film growth rate. The highly non-isothermal conditions which prevail account for the rapid rate of oxidation relative to furnace oxidation. Although both laser and furnace oxidation are thermal processes which obey a parabolic rate law, preliminary oxygen pressure dependence data indicate that they may not have the same rate determining step.
Synthesis of Diamond by Laser-Induced CVD
Authors: Kitahama K. , Hirata K. , Nakamatsu H. , Kawai S. , Fujimori N. , Imai T. 
Published: March 2011

AbstractSynthesis of diamond thin-films has been tried by an ArF excimer laser-induced chemical vapor deposition (LCVD) technique, using acetylene diluted with hydrogen as a source gas and a silicon wafer as a substrate. In these experiments, irradiation geometry, substrate temperature and laser power density were varied. Upon irradiation by a focused laser beam, deposition of diamond on substrates heated above 400°Cwas observed, and was confirmed by reflection electron diffraction (RED) photographs. Homogeneity of the diamond films was improved by irradiation parallel to the substrate. These facts suggest that the formation of diamond proceeds through multiple photon decomposition of the reactant gas, and that electronic excitation of gas phase rather than that of substrate or adsorbate layer is essential to form diamond.
Catalyzed Gaseous Etching of Silicon
Authors: Selamoglu N. , Mucha J. A. , Flamm D. L. , Ibbotson D. E. 
Published: March 2011

AbstractEtching of silicon by molecular fluorine is accelerated when trace quantities of copper are present on the surface. Copper is a residue formed when sputter-deposited aluminum (containing 0.5 % copper) is selectively removed by HF from the silicon surface. The temperature dependence of the etching rate was studied in the range 60–290°C. At temperatures higher than 80°C copper causes a ˜100-fold increase in the rate of etching of the underlying silicon (100), compared to unmetallized samples. Above 180°C, F2 exhibits a higher absolute etch rate than equivalent concentrations of fluorine atoms. Preliminary results for other metal contaminants and etchant gases indicate that silver also accelerates F2 etching, and copper enhances etching by NF3. The results are interpreted in terms of a catalytic mechanism.
Cl2 Reactive Ion Beam Etching of Heavy n-Type Si
Authors: Krueger E. Eric , Ruoff Arthur L. 
Published: March 2011

AbstractThe etch yield vs n-type doping level up to 1.5 × 1021 As/cm3 was measured. Also, the etch yield as a function of ion energy (300 to 1500 eV) for the heaviest doped samples (1.5 × 1021 As/cm3) was measured. Only a small 10–15 percent enhancement in etch rate over low doped silicon was observed. Channeling experiments with Rutherford backscattering spectrometry showed 84 percent of the arsenic atoms were in substitutional positions in the silicon crystal. In addition, silicon was implanted with arsenic to a dose of 1.25 × 1017 #/cm2 and then laser annealed. This produced samples with a 5000 angstrom layer of uniformly doped silicon at five atomic percent. Channeling experiments showed these samples to have 82 percent of the dopant in substitutional sites. Samples were then masked with chrome and etched at varied pressures, temperatures and ion energies. Within our experimental resolution no isotropic etching was observed. This small doping dependence of the etching behavior of n-type silicon in reactive ion beam etching suggests that the rate limiting step for Cl2 RIBE is different than for Cl2 RIE, rf-plasma and laser assisted etching. A discussion of this difference is given assuming a much lower concentration of atomic chlorine in RIBE.
A New Method for Analyzing Thin Sidewall Inhibitor Layers
Authors: McVittie J. P. , Lin T. A. , Bariya A. J. 
Published: March 2011

AbstractEtch inhibitor layers are the key to anisotropy for a number of dry etch processes, yet little is known about these layers because of the difficulty in analyzing them on the side walls where they form. In this paper we will show that an Al grid suspended above an etching surface can be used to suppress ion bombardment and allow the inhibitor to form on large horizontal surfaces which can be easily analyzed. The effect of ion bombardment on the nature of the inhibitor layer can also be elucidated using this technique. In conjunction with X-ray Photoelectron Spectroscopy, this method was used to look at the polymeric inhibitor formed during Si etching in SF6/C2CIF5 with and without the presence of photoresist.
Comparison of Low Intensity Laser Enhancement of Oxygen Chemisorption on GaAs Using O2 and N2O
Authors: Bertness K. A. , McCants C. E. , Chiang T. T. , Mahowald P. H. , Wahi A. K. , Kendelewicz T. , Lindau I. , Spicer W. E. 
Published: March 2011

AbstractThe sticking coefficient for molecular oxygen on GaAs(110) up to about one-halft monolayer coverage can be enhanced by two or three orders of magnitude when the semiconductor surface is illuminated by an argon ion laser with intensities of 5 W/cm2 or less. Previous work has shown that this effect is nonthermal and roughly independent of wavelength for above-bandgap radiation, implying that photogenerated electrons and/or holes are responsible in some way. In this paper we present recent work which shows that transfer of energy from the GaAs to oxygen molecules physisorbed on the surface causes the breakup of the oxygen and so enhances the reaction. This conclusion comes from comparison of our photoemission results for O2 and N2O exposures made under the same conditions, N2O being chosen since only 1.7 eV is needed to remove the oxygen atom as opposed to the 5.1eV required to break an O-O bond. Nitrous oxide, in contrast to O2, shows only slight photoenhancement and has a much lower activation energy for the dissociative sticking coefficient, demonstrating that removal of the dissociation of O2 as a reaction step also removes the major part of the activation energy barrier to oxygen chemisorption. Since N20 and photoenhanced O2 have similar kinetics, we conclude that the breakup of O2 is the reaction step accelerated by illumination. Another clue to the nature of the photoenhancement comes from our finding that both n- and p-type GaAs display similar O2 laser enhancement ratios. An estimate of the carrier concentrations at the surface predicts that electrons and holes are present in equal amounts at the surfaces of both doping types, however, so this result does not distinguish between single-carrier and recombination-related enhancement mechanisms.
UV Laser Processing of Semiconductor Devices
Authors: Sigmon T. W. 
Published: March 2011

AbstractThe use of a pulsed UV excimer laser based process for the incorporation of dopant impurities into Si is described. The process can result in high concentration shallow box like profiles suitable for submicron VLSI device fabrication. The process consists of exposure of the clean silicon surface to a doping gas (B2H6, AsH3, PH3) then driving the adsorbed monolayers of dopant into the Si by a melt-regrowth process initiated by a pulsed XeCl excimer laser. Modeling of the process allows prediction of the resulting doping profiles and electrical properties of the doped layers. Excellent crystal quality of the doped layers is found even without a postdoping anneal. Also, recent results indicate that post doping annealing may not be needed for improvement of the electrical characteristics of the doped layers provided certain conditions are met. Detailed descriptions of the process, results, modeling and device fabrication are presented.
GaAs Circuit Restructuring by Multi-Level Laser-Direct-Written Tungsten Process
Authors: Black Jerry G. , Doran Scott P. , Rothschild Mordechai , Sedlacek Jan H.C. , Ehrlich Daniel J. 
Published: March 2011

AbstractLaser-direct-writing processes are employed to fabricate a GaAs digital integrated circuit. The lithography-free techniques deposit and etch conductors and resistors, and remove insulating layers, thus enabling multilevel interconnections. These combined directwrite processes provide the flexibility of clip-lead prototyping on a micrometer scale.
Holographic Photoetching of High-Quality Diffraction Gratings in P-GaAs for Distributed Feedback Lasers
Authors: Matz Richard 
Published: March 2011

AbstractQuarter micrometer period diffraction gratings having depth-to-spacing ratios around 0.5 have been photochemically etched in p-GaAs using direct holographic illumination with 257 nm UV light. The results suggest the interaction of the incident light with the etched grating. The etch process is represented with the aid of a potential-pH diagram calculated from literature data.
In-situ Rapid Isiheial Pocessing of Thin Epitaxial Dieleciric Films on Silicon and Compound Semi Semiconductors
Authors: Singh R. , Radpour F. , Narayan J. , Joshi S. P. , Rahati M. , Anandakugan S. , Kahng S. K. 
Published: March 2011

AbstracrWe have developed a new rapid isothermal processing technique for the deposition of epitaxial dielectric films (II–VIa fluorides and their mixtures) on silicon and ccmpound semiconductors. In this process, epitaxial dielectric films are deposited in an e-beam system at room teqperature and subsequently subjected to in-situ rapid isothermal annealing by using incoherent light sources incorporated in the e-beam system. Epitaxial dielectric films of CaF2 and CaxS1−xF2 have been deposited on Si, GaAs and InP. In this paper, prelimilifty results of electrical and structural characteristics of. epitaxial dielectric films on Si and cupourd semiconductors are presented.
Quantification of Hydrogen and Determination of the Binding State in a-Si:H:D by Thermal Desorption Spectroscopy
Authors: Yabumoto Norikuni , Muramatsu Yasuji , Oshima Masaharu 
Published: March 2011

AbstractThermal desorption spectroscopy (TDS) is used to quantify the amount of hydrogen in hydrogenated amorphous silicon(a-Si:H) as well as to determine the binding state. It is possible to measure the quantity and binding state of hydrogen in 100–8000Å thick a-Si:H films. Hydrogen is incorporated in the 100Å thick film at a rate of about three times greater than that in the over 1000Å thick film. Hydrogen in all films is bonded to silicon with three kinds of binding states at 2.8, 3.1 and 3.3eV. a-Si:H:D is prepared from SiH4/D2 plasma in order to clarify the origin of hydrogen in the films which are usually deposited from SiH4 and diluted H2 gas. TDS spectra of H2, HD and D2 show that there is more hydrogen from SiH4 in the film in each of the binding states, than from the diluent H2.
Chemical Vapor Deposition of Gold
Authors: Larson Carl E. , Baum Thomas H. , Jackson Robert L. 
Published: March 2011

AbstractChemical vapor deposition of gold from dimethyl-2,4-pentandionato gold (III) and two fluorinated derivatives is reported. At substrate temperatures of 200–300°C, high purity gold films were obtained on SiO2 and Si substrates. Films with resistivities down to 1.3 times that of bulk gold were obtained at deposition temperatures of ∼200°C, where films with very small grain size could be deposited.
Photon and Ion Beam-Induced Chemistry of Palladium Acetate Films
Authors: Gross M. E. , Brown W. L. , Linnros J. , Harriott L. R. , Cummings K. D. , Funsten H. O. 
Published: March 2011

AbstractElectrically conducting palladium features have been produced by laser and ion beam irradiation of thin palladium acetate films. The photothermal reaction induced by scanned continuous wave Ar+ laser irradiation leads to metal lines that may exhibit periodic structure. This results from repeated propagation of “explosive” reaction fronts generated by coupling of the heat from the absorbed laser radiation with the heat of the decomposition reaction of the film. In contrast, 2 MeV He+ ion irradiation produces smooth metallic-looking features that contain up to 20% of the original carbon and 5% of the original oxygen content of the film. Films irradiated with 2 MeV Ne+ ions contain slightly lower amounts of carbon and oxygen residues, but fully exposed thick films (0.90 μm) appear black rather than metallic silver. In addition to having significantly higher purity, the laser-written features have lower resistivities than the ion beam-irradiated features. Infrared spectroscopy of the ion beam-irradiated films as a function of dose indicates a progressive loss in intensity of the characteristics acetate (COO-) vibrations. This occurs at doses lower than those associated with major C and O loss from the films. Partially ion-exposed films continue to decompose to metallic-looking material over a period of weeks after irradiation. Metallic palladium particles apparently catalyze this process.
Material Considerations in the Microfabrication of Grating Microstructures for use in a Laser-Powered Linear Accelerator
Authors: Warren John B. 
Published: March 2011

ABSTRACTCollaborative work between Brookhaven and Los Alamos National Laboratories is developing a new type of linear accelerator that uses a high-power, picosecond pulse CO2 laser to irradiate a specialized form of grating with a pitch of 10.6 microns. The electromagnetic field that results can be used to accelerate electrons at field gradients of several GeV/m with potential efficiencies much better than current accelerators. The grating must be conductive to minimize resistive losses, be able to withstand high fields without damage, and requires dimensional tolerances in the sub-micron range. These requirements focus attention on grating material selection, microfabrication methods, and metrological methods used for quality control. At present, several types of gratings have been manufactured by reactive ion etching of fused silica in CHF 3/Ar or etching silicon with KOH/H 2O or ethylenediamine-pyrocatechol solutions. Metrological analysis of the gratings has begun with a Tracor Northern 5700 digital image analyzer.
Localization and Electron-Electron Interaction Effects in Platinum Silicide Thin Wires
Authors: Ishida S. , Murase K. , Shimamoto Y. , Ishibashi K. , Gamo K. , Namba S. , Uematsu S. 
Published: March 2011

ABSTRACTThe low-temperature magnetoresistance of PtSi thin wires of varying width, prepared with different mask elements (Cu and Ni) in the reactive ion beam etching, has been studied, to determine the width dependence of the physical parameters in the weak localization. A drastic decrease of the magnetic impurity scattering time τs and that of the superconducting transition temperature Tc have been found for the wires prepared by Ni mask with narrowing width, which suggests that the phase coherence of diffusing electrons responsible for the weak localization and the superconductivity are strongly affected by the presence of a small amount of Ni impurities recoil implanted into the surface region of the sidewalls of wires.
Hot Jet Etching through Stencil Masks
Authors: Geis M. W. , Pang S. W. , Efremow N. N. 
Published: March 2011

ABSTRACTThis article contains a description of hot jet etching through stencil masks. The dry etching technique does not damage the stencil mask, but anisotropically etches GaAs at rates as high as 10 μm min−1. Resolution less than 50 nm has been demonstrated. At present the etched surfaces are rough, but improvement of the etching technique may result in smooth surfaces.
193-NM Excimer Laser-Assisted Etching of Polysilicon
Authors: Armacost K. D. , Babu S. V. , Nguyen S. V. , Rembetski J. F. 
Published: March 2011

ABSTRACT193-nm excimer laser-assisted etching of polysilicon was studied in vacuum and in the presence of Ar, CF3 Br, CF2 Cl2, and NF3. In inert atmospheres (vacuum, Ar) exposure to the laser led to jagged profiles at high fluences (>350 mJ/(cm2-pulse)) resulting from surface temperature gradients. At lower fluences, a resolidified Si-SiO2 lump was formed by thermal and surface tension gradients induced by laser heating. In the presence of 193-nm radiation, CF3Br showed some propensity to etch polysilicon, while CF2Cl2 did not show any appreciable etching.Etch experiments were also performed in the presence of NF3 Maximum etch rates of 0.6 A/pulse were obtained for pressures greater than 500 torr and fluences exceeding 200 mJ/(cm2-pulse). An adsorptive etch mechanism is proposed, where NF3 molecules diffuse to the surface, adsorb and then react after absorbing laser radiation. Etching of micron profiles in polysilicon was also examined.
Anisotropic and Selective Reactive Ion Etching of SiC in CHF3 and Oxygen Plasma
Authors: Pan W-S. , Steckl A. J. 
Published: March 2011

ABSTRACTThe use of CHF3 plus oxygen plasma to achieve selective and anisotropic patterning of SiC thin films in the reactive ion etching (RIE) mode is reported. Experiments were performed using various levels of oxygen percentage (from zero to 90%), pressure (from 20 to 300 mTorr) and power (from 100W to 350W). Anisotropic etching of SiC with a vertical-to-lateral etch ratio in excess of 8:1 was measured for a CHF3 + 75%02 mixture at 20mT pressure and 200W RF power. Under these conditions, the SiC etch rate was measured to be 400 A/min and the selectivity over Si was approximately 2.2:1. The effect of the cathode DC potential and emission intensity of various species in the plasma on the SiC and Si etch rates is considered.
Reactive Ion Etching of AI(Cu) Alloys
Authors: Hu C.-K. , Small M. B. , Schadt M. 
Published: March 2011

ABSTRACTReactive ion etching of Al( ≤ 4 wt.% Cu) and AI(Cu)/W films is described. Using single layer resist, 1 μm lines are demonstrated over 0.3 μm topography in the bilayer films and 0.5 um lines in the single layer layer films over planar surfaces. For Al alloys with Cu concentration in the ranges 2–4 wt.% it is found that clean etching is strongly dependent on deposition condition. A model is proposed to explain this.
Reactive Ion Etching of Multi-Layer Resist
Authors: ng H. Y. , Klaus D. P. , Polcari M. R. , molzen W. W. 
Published: March 2011

ABSTRACTMulti-layer resist has been utilized commonly in optical and E-beam lithography for its ability to resolve submicron feastures over topography. In addition, the use of a low-Z(atomic number) material as the intermediate layer reduces the proximity effect. This paper describes the development of etching process used to pattern a tri-level resist based on polyimide, an inorganic intermediate layer, and positive resist as top image layer. A highaspect-ratio image can be anisotropically transfered from the inorganic intermediate layer into the polyimide planarizing layer by oxygen RIE. Directionality, profile control, and backsputtering residue are the primary considerations during the pattern transfer etching. The influence of pressure, power and self-bias voltage on the etching process are described. The residue is caused by sputtering of the electrode material and the etch barrier material. Backsputtering residue from electrode can be prevented by covering all exposed conducting surfaces with an organic dielectric material, in this case an ardel plate. Etch residue contributed by the intermediate layer is quantified according to its pattern density and the influence of the pressure. Sidewall profiles and their relationship to planarizing layer thickness are also discussed.
Post Oxidation Anneal and Re-Oxidation Effects in 5 nm SiO2 Films
Authors: Dori L. , Arienzo M. , Sun Y. C. , Nguyen T. N. , Wetzel J. 
Published: March 2011

ABSTRACTUltrathin silicon dioxide films, 5 nm thick, were grown in a double-walled furnace at 850°C in dry O2. A consistent improvement in the electrical properties is observed following the oxidation either with a Post-Oxidation Anneal (POA) at 1000°C in N2 or with the same POA followed by a short re-oxidation (Re-Ox) step in which 1 nm of additional oxide was grown. We attribute these results to the redistribution of hydrogen and water related groups as well as to a change in the concentration of sub-oxide charge states at the Si-SiO2 interface. A further improvement observed after the short re-oxidation step had been attributed to the filling of the oxygen vacancies produced during the POA. High resolution Transmission Electron Microscopy cross-sectional observations of the Si-iSO2 interface have evidenced an increase in the interface roughness after the thermal treatment at high temperature. These results are in agreement with recent XPS data.
A Process for 0.5 Micron CMOS Gate Definition
Authors: Stanasolovich D. , Katz S. , Schnur S. , Danner D. , Wang L. K. 
Published: March 2011

ABSTRACTA RIE process has been developed for the etching of 0.5 μm CMOS Polysilicon gates defined using both E-Beam direct writing and sub-micron optical lithography. Profile control and selectivity were enhanced by using a two-step pattern transfer process wherein the Photoresist mask was used to define a thin Silicon Nitride layer which was subsequently used to define the underlying Polysilicon gate electrode. High etch selectivity to both the Silicon Nitride mask and the thin gate oxide was achieved using a Cl2 plasma chemistry after a BCl3 initiation step. The effect of BCl3 initiation on the poly profile and the effect of loading on profile and selectivity will be presented.
The Effect of Window Edge Stress on Dopant Diffusion in Silicon
Authors: Huang C. K. , Kook T. , Jaccodine R. J. 
Published: March 2011

ABSTRACTAn experimental study of dopant diffusion at Si3N4 and SiO2 film edge is reported. The results show that an alternation of enhanced and retarded diffusion of both As and Sb at the Si3N4/SiO2 film edge was observed after 1100°C heat treatment in N2. The observed effect has been correlated to the alternation of tensile and compressive stress field at the film edge for the first time. Additionally, the different shape of junction profile of As and Sb seems to be a result of impurity misfit strain effect. From this experiment, it is obvious that the interaction of film edge stress fields will make the control of dopant profile more difficult for smaller window width. Hence the film edge effect should be taken into account especially for the fabrication of submicron devices.