Showing papers on "Annealing (metallurgy) published in 1977"

Dependence of residual damage on temperature during Ar+ sputter cleaning of silicon

Abstract: It has been found that the kind and amount of damage produced in silicon following Ar+ ion bombardment at 1.0 keV and the annealing properties of the damage depend strongly on the temperature at which the sputtering is done in the range 25–800 °C. Some of these differences in damage are not evident with surface‐sensitive techniques such as LEED, RHEED, or AES, but have been revealed by transmission electron microscopy and by Rutherford ion backscattering. TEM examination of substrates annealed at 800 °C after being sputtered at temperatures in the range 25–800 °C shows an increase in the density and the size of crystal defects with increasing sputtering temperature. Rutherford ion backscattering shows an increase in silicon disorder and in retained argon with increasing sputtering temperature. These results are similar to observations reported for ion implantation at higher energies. Models for damage mechanisms are discussed briefly. It is concluded that for Ar+ ion sputter cleaning of silicon, the silic...

Ordering transformations and mechanical properties of Ti 3 Ai and Ti 3 Al-Nb alloys

Abstract: Phase transformations and the kinetics of domain growth were studied in near stoichiometric Ti3Al and in a similar alloy containing about 5 at. pct Nb (Cb). The alloys were quenched from the β and from the α+ β fields and were subsequently annealed in the α2 field to study the ordering transformation. The critical temperature (T c) for ordering was found to be between 1125 and 1150° for both alloys. When quenched from aboveT c the microstructure of the stoichiometric compound contained massive martensite with small antiphase domains of average size 8 × 10— μm. On annealing the quenched structures in the range 700 to 1000°, domain coalescence occurred, the domains growing approximately as the square root of the annealing time. The activation energy for the domain growth process was found to be 64.6 ± 6 Kcal/mole (2.68 ± 0.25 × 105 J/mole). On quenching the alloy containing Nb the β transforms to a fine acicular martensite. On annealing, antiphase domain coalescence within the martensite plates and the simultaneous recrystallization of the martensite resulted in a fine subgrain structure even after annealing at 900° for up to 3 h. The mechanical properties and the fracture modes of the two alloys tested at 700° were correlated with the observed microstructural changes. The effects of Nb in this alloy are to slow the domain growth kinetics, to reduce the planarity of slip, and to increase nonbasal slip activity.

Changes in Curie temperature, physical dimensions, and magnetic anisotropy during annealing of amorphous magnetic alloys

Abstract: We have measured the effects of annealing in air on various properties of several amorphous alloys. Reported here are results on the changes in Curie temperature, in the physical dimensions of lengths of amorphous ribbon, and in the magnetic anisotropy. Increases in Curie temperature up to 35°C have been measured. All the alloys examined show a steady increase in T c on annealing at low temperatures, but some compositions show a smaller increase in T c on annealing near the crystallization temperature than on annealing at lower temperatures. There appear to be two competing mechanisms influencing T c . All the alloys examined show a clearly measurable decrease in length on annealing; we interpret this as an increase in bulk density. The kinetics of the annealing are similar to those of the stress relaxation. Finally, annealing experiments on the shape of 60 Hz hysteresis loops show a decrease in the anisotropy associated with non-uniform internal stresses, but in some cases also show the slow development of a fairly strong uniaxial anisotropy with its easy axis perpendicular to the ribbon axis. This uniaxial anisotropy is tentatively ascribed to the development of an oxide layer during annealing, which in turn produces a uniform compressive stress due to differential thermal contraction and therefore a stress-magnetostriction anisotropy. The changes in Curie temperature and in sample dimensions cannot be ascribed to oxidation. All the results described above are for annealing treatments that do not cause crystallization. The time for crystallization at various temperatures has been measured, and activation energies for crystallization derived.

Annealing of vacancies and ageing in Al-Li alloys

Abstract: Quenching experiments have been carried out on a set of ‘dilute” Al-Li alloys by using resistivity measurements, and on a ‘concentrate” alloy containing 6·72 at. % Li, by using both resistivity and electron microscopy. A value of 0·25±0·03 eV has been determined for the Li-vacancy binding energy. The recovery after quenching of dilute alloys containing up to 0·38 at. % Li occurs in two stages as in pure Al; the first stage has been ascribed to the annealing of vacancy-Li couples formed during the quenching, whereas the second one has been attributed to the elimination of dislocation loops. By increasing Li content, some anomalies have been observed in the recovery after quenching, ascribed to short-range order phenomena. The concentrate alloy decomposes in the ageing after quenching by forming G.P. zones having an ordered Al3Li internal structure. High quenching temperatures (≥500°C) prevent G.P. zones from reaching the resistivity maximum, a result attributed to a reduction in the lifetime of va...

Study of Encapsulants for Annealing GaAs

Abstract: Low temperature photoluminescence and Auger electron spectroscopy have been used to study chemical-vapor deposited SiO2 and SigN4 layers as en- capsulants for high temperature annealing of GaAs. Silicon dioxide or silicon oxynitride layers allow out-diffusion of Ga, while suitably prepared rf plasma deposited SisN4 layers can be used to anneal GaAs with negligible Ga out- diffusion. Ion implantation is a versatile method of doping semiconductors and is an established fabrication step for many silicon devices (1). Although the use of implantation in the III-V compounds is less wide- spread, important device applications have emerged. These include the fabrication of light emitting diodes (2), GaAs field-effect transistors, optical waveguid.es, and detectors (3). Because of the difficulties of selec- tively doping GaAs or other compound semiconductors by standard diffusion processes as compared with Si, it now appears that implantation will play an increas- ing role in future device applications of compound semiconductors. In view of the potential for this doping method, it is important to develop reliable procedures for im- plantation and annealing in these materials. Ion im- plantation produces considerable lattice damage which must be annealed out in order to restructure the lattice and activate the implanted impurities. While this pro- cedure is relatively straightforward in Si, annealing a compound semiconductor such as GaAs is more difficult. The incongruent evaporation of Ga and As from GaAs at temperatures ~ in excess of 600~ (4) makes it impossible to anneal bare GaAs samples without surface degradation. It is thus necessary to encapsulate the sample with a suitable dielectric layer or to perform the anneal in a carefully controlled ambient (5. 6). There have been numerous discussions of implantation and annealing in GaAs using encapsu- lants such as sputtered or chemical,vapor deposited SiO2 (7), thermally o r reactively deposited or sput- tered Si3N4 (8-10), or sputtered A1N (11). In the present work we have used low temperature photo- luminescence (PL) and Auger electron spectroscopy _(AES) to investigate the annealing-encapsulation properties of chemical vapor deposited SiO2 and rf plasma deposited Si.~N4 layers on GaAs. It is well known from diffusion experiments in Si that Ga has a very high diffusion coefficient in SiO2 (12). Gyulai et

Annealing of surface states in polycrystalline‐silicon–gate capacitors

Abstract: Charge injection at the polycrystalline‐silicon–SiO2 interface of phosphorus‐doped, polycrystalline‐silicon–gate MOS capacitors can cause excess currents during quasistatic C‐V measurements and hysteresis in high‐frequency C‐V curves. The effect of annealing in nitrogen and forming gas at temperatures between 300 and 850 °C on these instabilities as well as on surface states Nss and surface charge Qss has been studied. To distinguish effects occurring at the substrate Si‐SiO2 interface from effects occurring at the polycrystalline‐silicon–SiO2 interface, measurements are also reported of the effect of annealing Si‐SiO2 structures without gate electrodes, in the same temperature range and atmospheres. There is a minimum in Nss after anneal of samples without electrodes in forming gas at 400 °C. Reaction with hydrogen is essential to anneal surface states; thermal anneal is not sufficient. Some reaction, possibly formation of SiO, occurs above 450 °C that increases Nss and may increase Qss. Anneal of polycr...

Electrical profiling and optical activation studies of Be‐implanted GaAs

Abstract: Differential resistivity and Hall‐effect measurements have been utilized to study the annealing behavior and electrical carrier‐distribution profiles of Be‐implanted GaAs. A maximum of 90–100% electrical activation occurs during 900 °C anneals for implanted Be concentrations less than ∼5×1018 cm−3. For higher fluences, however, a heavily concentration‐dependent diffusion is observed, and the measured electrical activation is complicated by outdiffusion of Be into the Si3N4 encapsulant. In these cases, a maximum in the electrical activation appears for annealing near 700 °C. Low‐temperature (5 °K) photoluminescence substantiates previous findings that 900 °C annealing results in maximum optical activation and lattice recovery.

Vacuum-deposited CuInTe2 thin films: Growth, structural, and electrical properties

Abstract: The growth, structural, and electrical characterization of vacuum‐deposited n‐ and p‐type CuInTe2 thin films utilizing a high‐evaporation‐rate technique (≳100 A/s) are reported. Complementary transmission electron microscopy (TEM) and Auger electron spectroscopy (AES) are used to investigate the films’ crystalline (grain size, orientation, structure) and compositional (elemental) properties. The effects of substrate temperature on these quantities are presented. A substrate temperature range (400

The optical properties of amorphous and crystalline silicon

Abstract: The optical constants n and k of amorphous and crystalline films of silicon have been found from measurements of reflectance and transmittance at normal incidence over the wavelength range from 2500 to 500 nm, and extended to 300 nm by the method of measuring reflectances from the specimen itself and after depositing on it a thin layer of Ta2O5. This latter method has also been made of the effects of annealing on amorphous films. The measurements on single-crystal silicon have been compared with the results of others obtained by Kramers-Kronig analysis.

A transmission electron microscopy investigation of filamentary superconducting composites

Abstract: The microstructure of the Nb3Sn grains in commercially produced superconducting filamentary composites has been studied using transmission electron microscopy. The mean grain size increased with annealing time and temperature while the degree of columnar growth decreased at higher temperatures. Correlation of grain size and superconducting properties showed that the maximum pinning force was obtained for a grain size of about 800 A.

Drawing and annealing of fibrous material

Abstract: The more‐than‐linear increase of elastic modulus with draw ratio, the gradual disappearance of meridional SAXS maximum, the drastic drop of elastic modulus after annealing and its recovery upon standing at room temperature if the sample was annealed with fixed ends so that it did not shrink, and the shape stability of such polyethylene samples and of superdrawn material (polyethylene, polypropylene, polyoxymethylene) during new annealing can be easily explained by the microfibrillar model of fibrous structure which was developed some years ago on the basis of electron microscopy and x‐ray and ir investigation of plastically deformed linear polyethylene and isotatic polypropylene.

Photovoltaic properties and junction formation in CuInSe2

Abstract: Studies of diffusion and photovoltaic effects in CuInSe2 p‐n junctions are reported. Junctions were formed by annealing Zn‐, Cd‐, and Cu‐plated p‐type samples at temperatures from 200 to 450 °C. The most efficient photodetectors are formed by 5–10‐min anneals at 200 °C with a calculated interdiffusion coefficient of ∼5×10−10 cm2/sec.

Dislocation networks in phosphorus-implanted silicon

Abstract: Observations, by transmission electron microscopy have been made on defects generated in 50 keV, high-dose (1 × 1015 to 3 × 1016 ions/em2) phosphorus-implanted silicon (111) wafers followed by 1100°C isothermal annealing in inert (dry N2) and oxidizing (wet O2) atmospheres. The formation of dislocation networks is closely associated with the generation of interstitial type dislocation loops which grow from point defects produced by ion implantation in silicon wafers. Also, dislocations grow more easily in wet O2 annealing than in dry N2. In wet O2 annealing, dislocation networks are formed by annealing within 1–2 min for samples implanted with doses above 3 × 1015 ions/cm2, and they move to deeper depths in the wafers during annealing. On the other hand, in dry N2 annealing, the critical ion dose for generation of dislocation networks is 1 × 1016 ions/cm2 and the location of dislocation networks in the wafers is usually unchanged during annealing. Such a difference in the generation and motion of...

A study of silicon oxides prepared by oxygen implantation into silicon

Abstract: A silicon oxide is formed by implanting high doses ( approximately 1017 cm-2) of O2 ions into an Si substrate. The properties (physical, chemical and electrical) of the formed layers are dependent on processing parameters such as accelerating voltage, ion dose and substrate temperature during the implant, and also on the post-implantation annealing treatment. The electrical properties of these implanted oxides are shown to be superior to those reported elsewhere. This is attributed to the implants being carried out at room temperature (a condition achieved by using low beam currents <15 mu A cm-2) and a suitable choice of annealing conditions to follow the implantation. The properties of the implanted oxides are compared to those of thermally grown oxides which were also prepared in this work.

On the shrinkage of rod‐shaped defects in boron‐ion‐implanted silicon

Abstract: Three different types of rod‐shaped defects formed during postimplantation annealing of boron‐implanted silicon are distinguished in annealing experiments carried out on transmission electron microscope specimens It is shown that rod‐shaped defects can be boron precipitates, Frank dipoles, or perfect a/2 <110≳ dipoles All shrink from the ends only during annealing The temperature dependence of shrinkage rate for the first type was determined by measuring dL/dt at three different temperatures for a given isolated defect Boron diffusion appeared to be the rate‐determining process The second type, Frank dipoles, were often observed to unfault, transforming into the third type during annealing At the time of unfaulting the newly formed perfect dipole was always observed to rotate on its glide cylinder to near edge orientation

Effects of heat treatment on structure and properties of 12%Cr steels

Abstract: Studies have been made of the effects ofaustenitizing and tempering heat treatments on the microstructures and mechanical properties of three 12% Cr steels. The effects of heat treatment on the constitution are shown to be in agreement with previously published data. In addition, the grain-refining actions of niobium carbonitride particles and delta ferrite have been demonstrated. Investigations of the tempering characteristics of the steels have shown that molybdenum, vanadium, and niobium accentuate secondary hardening and retard overaging primarily by inhibiting the annealing out of dislocations. Detailed descriptions of the tempering sequences have been given. Structure-property relationships have been investigated and the prior austenite grain size has been related to the Charpy impact transition temperature. Furthermore, the separate contribution of the strength of the material to the impact transition temperature has been established, together with the effect of the strength on the impact ...

Ion implantation as an ultrafast quenching technique for metastable alloy production: The Ag‐Cu system

Abstract: Substitutional solid solutions of Ag in Cu have been formed by ion implanting Ag at concentrations up to 16 at.%. The physical states of the implanted alloys were deduced by ion channeling and transmission electron microscopy and their stability was examined by annealing to 400 °C. The implantation results are compared with those obtained previously by conventional rapid quenching techniques.

Selenium implantation in GaAs

Abstract: The dependence of carrier concentration and mobility profiles on the dose of 400 keV Se ions implanted into Cr-doped semi-insulating GaAs, and on the annealing temperature has been studied for doses ranging from 3 × 10 12 /cm 2 to 2 × 10 15 /cm 2 and for annealing temperatures between 800 and 1000°C. Sputtered aluminum oxy-nitride and silicon nitride films were used as encapsulants for protection of the implanted surface during annealing treatments. The carrier profiles exhibited deep tails for implantations along both random and {110} planar directions. It was found that annealing temperatures of 900°C or above were necessary to obtain high carrier density and mobility values for implantation doses above 1 × 10 14 /cm 2 . Samples encapsulated with aluminum oxy-nitride films exhibited 3 to 4 times higher carrier concentration values and also slightly higher mobility values than those encapsulated with silicon nitride films. The maximum carrier concentration obtained was about 4 × 10 18 /cm 3 with aluminum oxy-nitride films as the encapsulant.

High‐rate sputtering of aluminum for metallization of integrated circuits

Abstract: Films of pure aluminum and alloys were deposited using planar magnetron sources in a load‐locked system with linear substrate motion. The influence on aluminum film properties due to the effects of sputtering gas pressure, source‐to‐substrate distance, deposition angle, substrate temperature, background gas level, and substrate‐temperature rise during deposition was studied for silicon wafers and other substrates. Substrate‐temperature rise during deposition was found to be a limiting factor in obtaining smooth, highly reflecting films. Ways to circumvent this limit will be discussed. They are the use of side shields to eliminate low‐angle deposition, reducing the nitrogen partial pressure, increasing the sputtering pressure, and deposition of the film in two or more passes over a source. High‐rate sputtering deposition and its effects on film and device properties are discussed. Radiation damage, which was minimal, was removed by annealing in forming gas at 425°C for 5 min. Step coverage of films deposited at ambient and at 300°C substrate temperature is also discussed.

Role of structural defects in electron transport properties of copper films

Abstract: Kinetics of annealing of the electrical resistivity (ρ), Hall coefficient RH, mobility μ, and thermoelectric power TEP of thin (160–5000 A) copper films deposited at temperatures ranging from 80 to 600 K have been studied. The activation energy for the associated recovery process has been obtained from the observed isothermal and isochronal changes in the resistance of the films. This energy increases from a value of 0.7 eV at 2000 A to 1.4 eV at 180 A for room‐temperature‐deposited Cu films. Changes in ρ, RH, and μ on annealing are found to decrease with film thickness and deposition and annealing temperatures. On the other hand, changes in TEP due to annealing increase with film thickness up to 3000 A; the rate of change depends sensitively on deposition temperature. With decreasing temperature of deposition, the reduction in TEP occurs at successively higher annealing temperature. Annealing does not affect the temperature dependence of RH and TEP. These results, together with the information on the mic...

Amorphous metallic and nitrogen containing alloy films

Abstract: These amorphous metal-alloy films include nitrogen, greater than about one atomic percent at least one transition metal selected from Cr, Fe, Co and Ni with at least one element forming an amorphous alloy therewith, selected from the "glass forming" elements, i.e., B, Si, Al, C and P. The alloys can be formed by deposition in a vacuum chamber. When films are sputtered, the target is composed of the above alloy elements with at least one element selected from each of the transition metal and glass forming element groups. Sputtering occurs in an atmosphere above about 2% vol. N 2 gas mixed with an inert gas, e.g., Ar. Alloys produced include N, i.e., (Co-Fe-B)N and (Fe-B)N. Above about 2 atomic % N in the film, films have lower values of saturation magnetization 4πM s . Above a 2% vol. N 2 gas in the plasma, electrical resistivity increases. Over 0.5% vol. N 2 gas in the plasma, the film's effective perpendicular anisotropy field H k * increases. For (Co-Fe-B)N, the anisotropy direction moves from in plane to perpendicular above 2% vol. N 2 plasmas. For (Fe-B)N, H k * increases with N 2 up to 10% vol. N 2 plasma. The N% in a film varies linearly with the log of N 2 % vol. Films show markedly improved adhesion, corrosion resistance and hardness. Magnetic thermal stability increases with N 2 above about 5% vol. N 2 in a plasma. Structural and magnetic properties are stable for annealing up to 400° C.

Semiconducting oxides. The effect of prior annealing temperature on dissolution kinetics of nickel oxide

Abstract: The paper describes studies of the dissolution rate of NiO (a p-type semiconductor) in nitric acid solution at 60°C as a function of prior annealing temperature in air. The dissolution rate per unit surface area decreased markedly on increasing the annealing temperature from 500 to 1450°C. This effect is not due to gross structural change or to major changes in dislocation density. The higher dissolution rates (i.e., > 10–12 mol cm–2 s–1) of oxide annealed at temperatures below 700°C is due to an excess concentration over thermodynamic equilibrium of point defects (nickel vacancies), introduced during decomposition of the hydroxide, and maintained as a consequence of limited diffusion. For annealing temperatures above 900°C, the defect concentration is roughly equal in all samples because of rapid equilibration in polycrystalline samples during cooling. The decreasing rates (i.e., < 4 × 10–13 mol cm–2 s–1) may be due to (i) limited conduction of charge due to changes in the space-charge region of the semiconductor and/or (ii) reduction of the density of kink sites on the surface of the more perfect crystallites.

Annealing of irradiation‐induced defects in arsenic‐doped silicon

Abstract: The annealing of the E3 (Ec−0.30 eV) and E4 (Ec−0.42 eV) defect levels in electron‐irradiated arsenic‐doped silicon has been studied by deep‐level transient spectroscopy. The annealing studies of the E4 defect level in the diffused junctions indicate first‐order kinetics with activation energies of 1.40 and 1.38 eV for the neutral and negative charge state of the defect, respectively. Even though the activation energies for thermal anneal at the two annealing modes are practically equal, charge state effects are operative. A secondary defect level E5 (Ec−0.24 eV) appeared in the spectrum during the annealing of the diffused p+nn+ junctions. The growth of E1 (Ec−0.17 eV) as the E4 defect anneals out seems to suggest that dissociation is the dominant process by which E4 is removed from the system.

The recrystallization of ion-implanted silicon layers

Abstract: Rutherford backscattering (RBS) and transmission electron microscopy (TEM) have been employed to investigate the annealing behaviour of Pb-implanted Si layers. The dose dependence of the post-anneal, residual disorder has been examined in considerable detail. Results indicate that the ability for the implanted Si layer to reorder as a single crystal decreases with increasing Pb concentration contained within the amorphous surface layers. The reordered Si layer is completely polycrystalline for Pb concentrations greater than a few atomic percent and the formation of this polycrystalline structure during annealing is accompanied by substantial Pb outdiffusion. Our observations lead us to suggest a step-by-step representation for Si recrystallization, where the reordered structure is dependent upon the local Pb concentration encountered as the regrowth process progresses from the bulk towards the Si suface.

The relationship between austenite strength and the transformation to martensite in Fe-10 pct Ni-0.6 pct C alloys

Abstract: The effect of austenite yield strength on the transformation to martensite was investigated in Fe-10 pct Ni-0.6 pct C alloys. The strength of the austenite was varied by 1) additions of yttrium oxide particles to the base alloy and 2) changing the austenitizing temperature. The austenite strength was measured at three temperatures above theM s temperature and the data extrapolated to the experimentally determinedM s temperature. It is shown that the austenite yield strength is determined primarily by the austenite grain size and that the yttrium oxide additions influence the effect of austenitizing temperature on grain size. As the austenite yield strength increases, both theM s temperature and the amount of transformation product at room temperature decrease. The effect of austenitizing temperature on the transformation is to determine the austenite grain size. The results are consistent with the proposal1 that the energy required to overcome the resistance of the austenite to plastic deformation is a substantial portion of the non-chemical free energy or restraining force opposing the transformation to martensite.