Showing papers on "Silicon published in 1982"

Mos (Metal Oxide Semiconductor) Physics and Technology

Abstract: Introduction. Field Effect. Metal Oxide Silicon Capacitor at Low Frequencies. Metal Oxide Silicon Capacitor at Intermediate and High Frequencies. Extraction of Interface Trap Properties from the Conductance. Interfacial Nonuniformities. Experimental Evidence for Interface Trap Properties. Extraction of Interface Trap Properties from the Capacitance. Measurement of Silicon Properties. Charges, Barrier Heights, and Flatband Voltage. Charge Trapping in the Oxide. Instrumentation for Measuring Capacitor Characteristics. Oxidation of Silicon--Oxidation Kinetics. Oxidation of Silicon--Technology. Control of Oxide Charges. Models of the Interface. Appendices. Subject Index. Symbol Index.

MOS /metal oxide semiconductor/ physics and technology

Abstract: Introduction. Field Effect. Metal Oxide Silicon Capacitor at Low Frequencies. Metal Oxide Silicon Capacitor at Intermediate and High Frequencies. Extraction of Interface Trap Properties from the Conductance. Interfacial Nonuniformities. Experimental Evidence for Interface Trap Properties. Extraction of Interface Trap Properties from the Capacitance. Measurement of Silicon Properties. Charges, Barrier Heights, and Flatband Voltage. Charge Trapping in the Oxide. Instrumentation for Measuring Capacitor Characteristics. Oxidation of Silicon--Oxidation Kinetics. Oxidation of Silicon--Technology. Control of Oxide Charges. Models of the Interface. Appendices. Subject Index. Symbol Index.

Electron and hole mobilities in silicon as a function of concentration and temperature

Abstract: An analytical expression has been derived for the electron and hole mobility in silicon based on both experimental data and modified Brooks-Herring theory of mobility. The resulting expression allows one to obtain electron and hole mobility as a function of concentration up to \sim 10^{20} cm-3in an extended and continuous temperature range (250-500 K) within ± 13 percent of the reported experimental values.

A graphical representation of the piezoresistance coefficients in silicon

Abstract: The longitudinal and transverse piezoresistance coefficients, Π(300 K), at room temperature are plotted as a function of the crystal directions for orientations in the

Auger and photoelectron line energy relationships in aluminum–oxygen and silicon–oxygen compounds

Abstract: Silicon–oxygen and aluminum–oxygen compounds exhibit significant XPS Auger and photoelectron chemical shifts that are accurately measurable. Chemical state plots of KLL Auger kinetic energy versus 2p photoelectron energy permit identification of chemical species from the locations of their points on the plots. The KLL Auger electrons of Al and Si were generated by the bremsstrahlung component of the radiation, with conventional instrumentation. The location of points on the plots can be understood on the basis of polarizability of the environment (on the Auger parameter grid of lines, slope +1) and on the basis of the factors contributing to the energy of the final state ion in the Auger transition (a grid of line, slope −1). Tetrahedral aluminum has a significantly smaller Auger parameter than octahedral aluminum, and this difference is repeated, but with reduced magnitude on the similar plots for silicon and oxygen lines for the same compounds. Otherwise, the Auger parameters for this class of compounds...

Vapor Deposition of Diamond Particles from Methane

Abstract: Microcrystalline diamond has been formed on silicon or molybdenum substrates by vapor deposition from a geseous mixture of methane and hydrogen. Cubo-octahedral or multiply-twinned crystals were obtained. The structure of the deposits was identified by electron diffraction and Raman scattering.

Growth of diamond particles from methane-hydrogen gas

Abstract: Microcrystals of diamond were grown on non-diamond substrates including silicon, molybdenum and silica, as well as on diamond by chemical vapour deposition. Deposition was carried out by passing a mixture of hydrocarbon and hydrogen gases through a heated reaction chamber in which a hot tungsten filament was held near the substrates. The deposit was identified by reflection electron diffraction and Raman spectroscopy. The effects of experimental conditions on the growth features were studied.

On tunneling in metal‐oxide‐silicon structures

Abstract: The analysis of Fowler‐Nordheim tunneling data in metal‐oxide‐silicon structures is reviewed. It is concluded that a parabolic dispersion relation for SiO2 and an electron effective mass of mox = 0.5m provide the best description of the experimental results, this conclusion is consistent with recent band structure calculations for SiO2. Also included is a brief discussion of the transverse momentum conservation issue for tunneling from silicon of 〈100〉, 〈110〉, and 〈111〉 orientation into SiO2.

Raman scattering from hydrogenated microcrystalline and amorphous silicon

Abstract: Raman scattering measurements on hydrogenated microcrystalline silicon prepared in a hydrogen plasma at deposition temperatures between approximately=65 and 400 degrees C are presented and discussed. The shifts of the crystalline (c) and 'amorphous-like' (a) components of the spectra to lower frequencies with decreasing crystallite size have been correlated with the lattice expansion and the finite dimensions of the crystallites in these films. The roles of hydrogen and of the compressive stress in the samples have been investigated by annealing experiments and a deposition of the samples under negative bias of the substrate, respectively. These results point to a probable mechanism of the crystalline-amorphous transition in silicon. The data presented allow an assignment of the amorphous-like feature in the Raman spectra to surface-like modes at grain boundaries of the crystallites. Strong arguments are given that suggest that the 480 cm-1 peak in the Raman spectra of X-ray amorphous silicon is of the same origin and is hence associated with some shearing modes of Si clusters rather than a broadened density of states. Results on the depolarisation ratio of Raman scattering in the microcrystalline and X-ray amorphous films are also presented and discussed.

Direct measurement of gap state absorption in hydrogenated amorphous silicon by photothermal deflection spectroscopy

Abstract: We have measured the subgap otpical absorption of undoped, singly doped, and compensated hydrogenated amorphous silicon down to 0.6 eV using the sensitive technique of photothermal deflection spectroscopy. We show that this absorption is due to silicon dangling-bond defects located approx.1.4 eV below the conduction band. While doping also creates defects approx.1.4 eV below the conduction band, compensation removes them. The results suggest that for the undoped material the density-of-states maximum found in field-effect measurements is due to silicon dangling bonds.

Defects in silicon

Abstract: The method of obtaining pure polycrystalline silicon is described, followed by short accounts of how this material is converted into single-crystal form either by the Czochralski (CZ) pulling method or the float-zone (FZ) method. It is shown that the silicon contains various impurities including oxygen, carbon, boron and possibly hydrogen. The defects and impurities often show a nonhomogeneous distribution in the form of helical swirls. Heat treatment of silicon-containing oxygen leads to the clustering of this impurity. At 450 degrees C there is formation of small complexes that act as shallow donors. Investigations using IR and ESR spectroscopy have so far failed to determine the atomic configuration of the defects. Heating at higher temperatures causes wide-scale precipitation of oxygen. There are interactions with carbon and there can be formation of silicon carbide precipitates. Contamination from Cu, Au, Fe, etc., can occur during these treatments and methods for gettering these metals are discussed, involving dislocations and silica precipitates. Low-temperature irradiations produce vacancies and self-interstitials which combine with impurities to form complexes on heating from 4K to 300K. Evidence is presented to illustrate the possible charge states of self-interstitials. Damage produced by fast neutrons is discussed next, followed by a brief account of neutron transmutation doping whereby neutrally occurring 30Si is converted to 31P by the capture of thermal neutrons. Some aspects of high-temperature diffusion are discussed and attempts are made to correlate the data with that derived from the irradiation studies.

Optical absorption of silicon between 1.6 and 4.7 eV at elevated temperatures

Abstract: The optical absorption coefficient of silicon for photon energies between 1.65 and 4.77 eV (750– 260 nm) has been determined at elevated temperatures (up to 700 °C) using polarization modulation ellipsometry. For photon energies below ∼3 eV (∼410 nm), the absorption coefficient increases exponentially with temperature from room 24° C to 700 °C, increasing by a factor of approximately 5 over that temperature range. The threshold for direct band‐gap absorption moves to lower energies with increasing temperature.

The Oxidation of Shaped Silicon Surfaces

Abstract: Nonplanar silicon surfaces were prepared and oxidized at 900°–1100°C and the oxide morphology was studied by transmission electron microscopy of thin sections. A 30% decrease in oxide thickness at silicon step edges following 900° and 950°C wet oxidation is attributed to the effect of locally compressive intrinsic stress within the oxide on the solubility of oxygen. Oxidation inhibition becomes less at higher temperatures due to the relief of stress (during growth) by viscous flow of the oxide.

Vibrational Study of the Initial Stages of the Oxidation of Si(111) and Si(100) Surfaces

Abstract: Using high-resolution electron energy loss spectroscopy (EELS) the vibrations of Si(111) and Si(100) surfaces in the early stages of oxidation have been investigated. Three different stages of oxidation, the last being the formation of a thin layer of vitreous SiO2 are identified when the surfaces are held at a temperature of 700K during the exposure with molecular oxygen. We show that also the first two stages involve atomic oxygen in bridging positions between silicon atoms. Small exposures at low temperatures (100 K) produce vibrational features of a different, possibly molecular, species. For higher exposures at the same temperature the spectrum again develops the characteristics of atomic oxygen and the molecular species eventually disappears. Exposure at room temperature leads to a mixture of atomic and molecular oxygen for smaller exposures and to purely atomic oxygen for exposures greater than ∼ 102 L. At room temperature even exposures as high as ∼ 1011 L do not produce the spectrum of vitreous SiO2. The same is found for the “natural”, room temperature grown, oxide layer on silicon wafers which we have studied by introducing the sample into the spectrometer through an air-lock. Annealing of the wafer to 700 K produced the characteristic spectrum of vitreous SiO2. The results are discussed in comparison with previous work.

Origin of the 0.82‐eV electron trap in GaAs and its annihilation by shallow donors

Abstract: The concentration of the major electron trap (0.82 eV below the conduction band) in GaAs (Bridgman grown) was found to increase with increasing As pressure during growth. It was further found that (for a given As pressure) the concentration of this trap decreased with increasing concentration of shallow donor dopants (Si, Se, and Te). Donor concentrations above a threshold of about 1017 cm−3 led to the rapid elimination of the trap. On the basis of these findings, the 0.82‐eV trap was attributed to the antisite defect AsGa formed during the postgrowth cooling of the crystals.

Oxygen diffusion and thermal donor formation in silicon

Abstract: The information available on the diffusion of oxygen and on the formation of thermal donors in silicon is critically reviewed. In this context the effects of intrinsic point defects on the diffusion-controlled growth of oxygen precipitates is investigated in some detail. Seemingly contradictory experimental results on the diffusivity of oxygen in silicon at temperatures around 400° C are explained in terms offast-diffusing gas-like molecular oxygen in silicon. The concept of molecular oxygen is also invoked in a newly suggested model of thermal donor formation in silicon. The diffusivity of molecular oxygen in silicon is estimated to be around 10−9cm2s−1 at 450° C, almost nine orders of magnitude higher than the diffusivity of atomic oxygen in interstitial position.

Temperature profiles induced by a scanning cw laser beam

Abstract: We present calculations of the temperature profiles induced by a moving cw elliptical laser beam with a Gaussian intensity distribution in a semi‐infinite material. Temperature‐dependent thermal diffusivity, conductivity, and surface reflectivity are incorporated in our model, and some aspects of melting are discussed. As an example, we apply the calculations to silicon. For a comparison of stationary elliptical spots of varying eccentricities, we present material‐independent normalized linear temperature profiles. We find that highly elliptical beams can be used to rapidly scan and anneal large areas.

Some observations on the amorphous to crystalline transformation in silicon

Abstract: An atomistic model for the transformation of amorphous (α) to crystalline silicon films while in contact with a crystalline substrate is presented. The atomic structure of the {100}, {110}, and {111} surfaces is examined and related to the observed interface migration rates. The assumption that for an atom to attach successfully to the crystal it must complete at least two undistorted bonds, leads to the prediction that the {100} amorphous/crystalline interface should advance fastest and the {111} slowest. The origin of crystal defects is discussed in terms of the atomistic recrystallization mechanism. Microtwins are found to be a logical consequence of crystallization on the {111} surfaces but are not expected to form on any other interface. Once microtwins are formed they can increase the recrystallization rate of a {111} surface. This phenomenon is both described in the model and experimentally observed.

A batch-fabricated silicon capacitive pressure transducer with low temperature sensitivity

Abstract: A batch-fabricated solid-state capacitive pressure transducer has been developed using silicon integrated-circuit technology The fabricated devices exhibit a dynamic range of 350 mmHg and a pressure sensitivity of about 1100 ppm/mmHg The temperature coefficient of zero-pressure offset is about +50 ppm/°C (less than 005 mmHg/°C) and the temperature coefficient of pressure sensitivity over the -20 to +50°C temperature span is about +275 ppm/°C (less than 004 mmHg/°C) when the device is used with an open or vacuum-sealed reference cavity These temperature coefficients are substantially lower than those of previously reported monolithic devices and are low enough that expensive temperature trims can be eliminated for many applications

The structures and vibrational spectra of crystals and glasses in the silica-alumina system

Abstract: Solar furnace melting and fast-quench techniques have been used to prepare SiO2Al2O3 glasses to high alumina content (near 60 mol% Al2O3), which have been studied by Raman spectroscopy. These spectra may not be simply interpreted. The structures of crystalline compounds in the SiO2Al2O3 system are discussed in relation to their vibrational spectra. On the basis of this discussion and other considerations, a structural model for the silica-alumina glass system is proposed, which is consistent with the stable or metastable immiscibility suggested along this join. The essential features of this model include a modified silica structure at low alumina content, and “structure-broken” regions at high alumina compositions, with silicon in tetrahedral coordination, but aluminium assuming a variety of bonding geometries. These are proposed to include aluminate tetrahedra with higher polymerization than simple corner-sharing, and less well-defined polyhedra of higher average coordination number.

A thermodynamic criterion of the crystalline-to-amorphous transition in silicon

Abstract: It is shown that the crystal lattice expansion of microcrystalline silicon leads, in the limit of small crystallite size of about 30 A, to an instability of the diamond structure with respect to the amorphous phase. Simple thermodynamic considerations are presented which support the idea of the crystalline-to-amorphous transformation being a discontinuous order—disorder phase transition.

Advantages of thermal nitride and nitroxide gate films in VLSI process

Abstract: Thin gate SiO 2 films thinner than 200 A often deteriorate throughout developmental VLSI processes, including refractory metal or silicide gates and ion- or plasma-assisted processes. Thermal nitridation of such SiO 2 films improves the MOS characteristics by producing surface protective layers against impurity penetration and by producing good interfacial characteristics. This fact indicates that a thermally grown silicon nitride film on a silicon substrate is the most promising candidate for a very-thin gate insulator. Experimental data show significant benefits from the nitride film for future VLSI devices.

Deuterium passivation of grain-boundary dangling bonds in silicon thin films

Abstract: Hydrogen passivation of silicon grain boundaries has been investigated by using deuterium as a readily identifiable isotope which duplicates hydrogen chemistry. Deuterium detection with high sensitivity was achieved with secondary‐ion mass spectrometry. Diffusion of deuterium in single‐ crystal silicon and polycrystalline silicon thin films at low temperatures (e.g., 350 °C) clearly demonstrates enhanced diffusion along grain boundaries. Defects at grain boundaries were detected by electron‐spin resonance and identified as silicon‐dangling bonds. Deuterium passivation of grain boundaries is revealed by correlated deuterium diffusion and dangling‐bond annihilation in polycrystalline silicon films.

Threshold switching in hydrogenated amorphous silicon

Abstract: Threshold switching is observed in n+‐i‐n+ sandwich structures of hydrogenated amorphous silicon after an initial forming process. At the threshold voltage the device switches from a low conductance to a high conductance state. The devices remain stable after more than 109 switching operations at a pulse frequency of 10 kHz. It is suggested that in the high conductance state filamentary conduction occurs in a permanent altered region created during the forming process.

A physical model for the dependence of carrier lifetime on doping density in nondegenerate silicon

Abstract: A theoretical model that describes the dependence of carrier lifetime on doping density, which is based on the equilibrium solubility of a single defect in nondegenerately doped silicon, is developed. The model predictions are consistent with the longest measured hole and electron lifetimes reported for n -type and p -type silicon, and hence imply a possibly “fundamental” (unavoidable) defect in silicon. The defect is acceptor-type and is more soluble in n -type than in p -type silicon, which suggests a longer fundamental limit for electron lifetime than for hole lifetime at a given nondegenerate doping density. The prevalent, minimum density of the defect, which defines these limits, occurs at the processing temperature below which the defect is virtually immobile in the silicon lattice. The analysis reveals that this temperature is in the range 300–400°C, and thus emphasizes, when related also to common non-fundamental defects, the significance of low-temperature processing in the fabrication of silicon devices requiring long or well-controlled carrier lifetimes.

The Bainite reaction in Fe-Si-C Alloys: The primary stage

Abstract: The morphology, crystallography, and substructure of bainitic ferrite formed in silicon alloyed high-carbon steels in the temperature range 290 to 380 °C have been studied. The bainite exhibits a plate shaped morphology, an irrational habit plane, and an irrational orientation relationship. The bainitic ferrite is heavily dislocated, while the surrounding austenite contains thin twins, the density of which is highest in the austenite between closely spaced ferrite plates. The bainite plates can cross these twins in such a manner that the twinned region remains in a crystallographic orientation, which is quite different from that of the other regions of the bainitic ferrite plates. Epsilon carbide subsequently precipitates on the austenite twin/bainitic ferrite boundaries. The bainitic ferrite shape strain direction and magnitude are estimated from displacements of austenite twins inherited in the ferrite. All results, including measurement of the austenite carbon content, are consistent with a shear mode of transformation.

Determination of the hydrogen diffusion coefficient in hydrogenated amorphous silicon from hydrogen effusion experiments

Abstract: The high‐temperature hydrogen evolution process from undoped hydrogenated amorphous silicon (a‐Si:H) is known to be diffusion limited. A formula is derived by which the hydrogen diffusion coefficient can be inferred from hydrogen effusion spectra taken at different heating rates or on films of different thickness. Experimental results for glow‐discharge a‐Si:H films prepared at various laboratories are presented and an excellent agreement to literature data of the hydrogen diffusion coefficient is obtained for undoped and phosphorus‐doped samples. For boron‐doped films, on the other hand, surface desorption of hydrogen from internal surfaces (voids) is found to be the rate‐limiting process for hydrogen evolution.

Theory of the peroxy-radical defect in a -Si O 2

Abstract: We have investigated the peroxy-radical defect in glassy Si${\mathrm{O}}_{2}$ by means of MOPN, a semiempirical molecular-orbital program, applied to a cluster of atoms chosen to simulate the defect. Our calculations are consistent with important features of Griscom's model of the defect as a perturbed ${\mathrm{O}}_{2}^{\ensuremath{-}}$ ion substituted for a single-bridging ${\mathrm{O}}^{2\ensuremath{-}}$ ion in Si${\mathrm{O}}_{2}$ and attached to a single silicon, and they place geometrical constraints on the defect structure for this model to be valid. We predict the existence of a related defect (the small peroxy radical, or SPR) wherein the peroxy radical is strongly bonded to two silicons. We have also investigated the formation of the peroxy radical. Griscom and co-workers envision peroxy linkages substituting for single-bridging oxygens during the growth process. They suggest that upon annealing these linkages readily give up an electron to form the observed radical. Our calculations lead us to argue against this process; rather, capture of a free hole seems more likely. We suggest that the SPR could form via a process in which neutral oxygen molecules diffuse through the solid and combine with ${E}_{1}^{\ensuremath{'}}$ centers to form peroxy radicals.