Showing papers on "Silicon published in 1970"

A quasi-static technique for MOS C-V and surface state measurements

Abstract: A quasi-static technique is discussed for obtaining the ‘low frequency’ thermal equilibrium MOS capacitance-voltage characteristics The method is based on a measurement of the MOS charging current in response to a linear voltage ramp, so that the charging current is directly proportional to the incremental MOS capacitance With this technique, surface potential and the surface state density can be obtained relatively simply and over a large part of the energy gap on a single sample, while also providing a direct test for the presence of gross nonuniformities in MOS structures This method has been used to determine the surface state distribution at the interface of a bias grown steam oxide and 10 ω-cm n -type silicon, and the results are compared with composite measurements using the conductance technique for a similar interface The sensitivity for surface state density measurements is estimated to be of the order of 10 10 states per cm 2 eV near mid-gap for 10 ω-cm silicon and improves with decreasing doping density Some applications and limitations are also briefly discussed

Electron tunneling and contact resistance of metal-silicon contact barriers

Abstract: The contact resistance of Al and Pt on n -type Si over a wide range of doping concentrations (10 18 → 2 × 10 20 cm −3 ) has been measured at both room temperature and liquid nitrogen temperature. These experimental results are compared with theoretical calculations based on a model with electron tunneling through the potential barrier at the interface as the dominant mechanism of current flow. Good agreement is found. It is hoped that this physical model can be used as a guideline in developing ohmic contacts for various semiconductor devices.

Esr and optical absorption studies of ion‐implanted silicon

Abstract: The g value, line shape, and linewidth of an ESR signal in Si layers which have been damaged by ion implantation of Si, P, or As at room temperature are found to be identical to those of the electron states observed in amorphous Si films prepared by rf sputtering. Interference phenomena observed in the optical absorption spectra allow a determination of the depth to which the Si has been damaged by the energetic heavy ions. These two techniques together provide a new tool for investigating lattice disorder in ion‐implanted Si layers.

Concentration and Behavior of Carbon in Semiconductor Silicon

Abstract: The concentration of carbon in semiconductor silicon and the behavior of carbon in the fusion and crystallization of silicon have been studied by the use of charged particle activation analysis. The solubility of carbon in solid silicon has been found to be or slightly less at the melting point, and the equilibrium distribution coefficient of carbon between solid and liquid silicon has been determined to be . Carbon content over the above solubility value has seldom been observed in silicon single crystals produced by modern industrial techniques. The content appears to depend more on the growth conditions of the single crystal than on the chemical purification method. The phase diagram of the C‐Si system in the extremely low carbon concentration range is given, together with a discussion of the kinematics of the carbon behavior in zone melting. Also, a new technique for studying the evaporation of carbon from the silicon melt is shown.

The strength and oxidation of reaction-sintered silicon nitride

Abstract: The structure of reaction-sintered silicon nitride is studied using scanning electron and optical microscopy at various stages during nitriding, for a range of nitriding and compacting conditions. The strength is then evaluated and interpreted in terms of the microstructure. It is found that fracture always occurs in a brittle manner by the extension of the largest pores. The effects of prolonged annealing in air above 1000† C on both the structure and strength are investigated. At 1400† C, cristobalite is formed. If the temperature is then maintained above 250† C, the strength is enhanced, but below this temperature the oxide layer cracks and reduces the strength.

The Effect of Silicon and Manganese on the Oxidation Mechanism of Ni-20 Cr*

Abstract: Additions of 3% silicon or manganese to Ni-20 Cr reduced the oxidation rate, whereas additions of 1% had little effect. Three percent silicon alloys formed an inner scale of SiO2, and 3% manganese alloys formed an inner spinel layer of essentially pure MnCr2O4. The experimentally determined solid-state growth rate of NiCr2O4 was about 1000 times slower than the growth rate for Cr2O3. It has been established that the protective layer on Ni-20 Cr (Nichrome alloys) is the spinel and not Cr2O3 as previously postulated. The mechanism for scale growth is discussed for Ni-20 Cr alloys.

Properties of glow-discharge deposited amorphous germanium and silicon

Abstract: Films of silicon and germanium are deposited on glass using the radio-frequency glow-discharge decomposition of silane and germane gases respectively. When grown on a substrate at room temperature the films are amorphous, with a short range order of about 20 A. The resistivities of these films, as deposited, are typically 108Ω cm for silicon and 7 × 103 Ω cm for germanium, measured at 294°K. Thermal activation energies for conduction decrease continuously below the deposition temperature, and at low temperatures germanium follows the relation log ’ = A/T 1 4 , where A is a constant. This would seem to indicate that a hopping process in an impurity band is responsible for conduction at low temperatures. Photoconductivity has been observed in silicon but not in germanium. The threshold energy for this effect decreases with increasing deposition or annealing temperatures. This is also true of the high temperature thermal activation energy. It is suggested that this is due to the de-localisation of states in the valence and conduction bands as the short range order increases. The optical absorption coefficients of germanium and silicon have an exponential dependence on photon energy and the considerable absorption below the fundamental absorption edge of the crystalline form may indicate the presence of localised states in the band gap.

Avalanche Injection of Electrons into Insulating SiO2 Using MOS Structures

Abstract: A model is presented to explain the direct current which flows when a metal‐SiO2–Si (MOS) capacitor is driven by a large‐amplitude ac signal sufficient to produce avalanche breakdown in the silicon. During the portion of each cycle that the silicon is in avalanche breakdown, minority carriers generated by impact ionization are accelerated towards the interface. It is assumed that some of these minority carriers attain sufficient energy to surmount the potential barrier at the interface, enter the SiO2, and result in a dc component of current. Experimental results from MOS structures with p‐type silicon substrates (electron injection into the SiO2) are shown to be consistent with this model. If the energy distribution of hot electrons in the Si avalanche plasma is Maxwellian, the data indicate that the effective temperature is 5550°K.

Silicon gate technology

Abstract: This paper describes the technology and characteristics of insulated-gate field-effect transistor integrated circuits using deposited polycrystalline silicon as the gate electrode. After a brief outline of the characteristics of the silicon gate technology, some of the basic properties of the silicon-silicon dioxide-silicon system, the processing steps for the fabrication of silicon-gate devices, and the electrical characteristics of the devices obtained will be reviewed. A comparison between silicon gate technology and standard technology will be carried out, using the 3705, an eight-channel multiplexer switch with decoding logic. Design considerations for silicon gate technology and some design examples will be given.

Vacancy Clusters in Dislocation-Free Silicon

Abstract: Dislocation‐free silicon crystals made by the floating zone technique contain vacancy clusters formed during cooling of the crystal after growth. The distribution and concentration of these defects have been determined. A model is presented describing the formation of these clusters. The influence of vacancy clusters on the leakage current of planar diodes is investigated.

An electrostatic developer containing modified silicon dioxide particles

Abstract: A developer material comprising colored toner particles having a particle size less than about 30 microns and a minor proportion of submicroscopic silicon dioxide additive particles having at least a portion of the silicon atoms on the outside surface of the silicon dioxide particles directly attached through an oxygen atom to another silicon atom which is in turn directly attached through a carbon linkage to one to three organic groups.

Channeling study of boron‐implanted silicon

Abstract: The channeling technique has been used to determine the lattice location of boron implanted into silicon by using the B11 (p,α) nuclear reaction. Approximately 30% of the boron lies on substitutional sites after a room‐temperature implantation of 3×1015/cm2. The substitutional content decreases with annealing temperature up to 700 °C and then increases at higher annealing temperature. This explains a reverse annealing behavior observed in the carrier concentration. Nearly all of the boron lies on substitutional sites after annealing at 1100 °C. The nonsubstitutional boron atoms do not occupy the normal tetrahedral interstitial sites. For annealing temperatures up to 500 °C they appear to lie along atomic rows, but they do not lie midway between row lattice sites. After higher‐temperature annealing their location appears less well‐defined.

Electrochemically controlled thinning of silicon

Abstract: A method for precision thinning silicon integrated circuit slices has been developed whereby either n or p type regions may be selectively removed from material of opposite conductivity. The existence of a simple and economical means to attain precise thickness control permits more complete advantage to be taken of many silicon IC structures. For example, precise thickness control, together with anisotropic1 etching of isolation/separation slots, is expected to permit economical fabrication of high component density, air-isolated monolithic2 integrated circuits.

Emission and Capture of Electrons at Sulfur Centers in Silicon.

Abstract: Abstract The electron thermal emission and capture rates and the electron impact ionization rate of trapped electrons at the sulfur donor centers in the depletion region of reverse biased silicon p-n junctions have been measured by the dark capacitance and current transient methods. Least square fits of the low field data give the following electron thermal emission rates: en0t = 1.64 × 1010(T/300°K)2exp [−276/kT] sec for the neutral center and en−1t = 1.03 × 1012 (T/300°K)2 exp [−528/kT] sec for the singly ionized center where kT is in meV. The thermal activation energies are then 276 and 528 meV respectively. The hole emission rates are much smaller and not determined. The electric field dependences of the thermal emission rates of electrons are considerably smaller than that predicted by the Poole-Frenkel theory applied to the ground state: en0t increased by 1.5 at 130°K from 0.2 to 1.0 × 105 V/cm and en−1t by 3 at 200°K. Electron capture coefficients are obtained from capacitance transient during steady state electron injection into the junction depletion layer either by transistor emitter or by optical generation at the surface next to the junction. The electron capture rate at the doubly charged center, cn−2t, decreases from 5 × 10−7 cm3/sec at 3 × 104 V/cm to 10−7 cm3/sec at 1.0 × 105 V/cm with essentially no temperature dependence. The electron capture rate at the singly ionized centers, cn−1t, obtained at 82°K was about two orders of magnitude smaller than cn−2t but had essentially the same electric field dependence. The electron impact ionization rate of trapped electrons at the neutral centers and its electric field dependences were also determined at 82°K.

High frequency bulk semiconductor amplifiers and oscillators

Abstract: Stable high frequency oscillating and amplifying devices are prepared from bulk semiconductor materials which have a positive differential conductivity at relatively low frequencies and a negative differential conductivity in some ranges of relatively high frequencies. The materials used are further characterized in that there is charge carrier transfer or population redistribution from a lower mobility band or low mobility impurity level to a higher mobility band, an effect opposite to that of Gunn effect devices. Materials suitable for the devices of this invention may be selected from a representative group of suitably doped III-V compounds, for example, N-type InSb, N-type alloys of the form InxGa1 xAs, where 0.53

The lattice location of boron ions implanted into silicon

Abstract: Channeling‐effect measurements have been used to investigate the lattice location of boron atoms implanted into silicon at an energy of 56 keV and with doses in the interval 1014–1015 ions/cm2. Measurements have been made as a function of implantation temperature and subsequent anneal treatment. The effect of post‐bombardment with different doses of 680‐keV protons has also been investigated.

Dyson Effect in the Electron Spin Resonance of Phosphorus Doped Silicon

Abstract: Dyson effect was investigated in the electron spin resonance of phosphorus doped silicon to know the dynamical characteristics of the paramagnetic center responsible for the single adsorption line around g -value of 2. Experiments were carried out at room, liquid nitrogen and liquid helium temperatures using samples of rod shape containing phosphorus atoms about 10 17 , 10 18 and 10 19 cm -3 . Theoretical line shape was calculated to simulate the effect of parameters such as sample thickness, skin depth and diffusion time of electrons through the skin depth. The observed absorption line showed distortion consistent with the Dyson theory. The diffusion time was estimated to be several times of the electron spin relaxation time. Comparing with the diffusion time calculated from the electron mobility, a model is proposed that there might be two types of electron motion, namely rapid motion in an impurity cluster and slow transitions among the clusters.

Effects of Material and Processing Parameters on the Dielectric Strength of Thermally Grown SiO2 Films

Abstract: The influence of several material and processing parameters on the dielectric trength of thermally grown films on silicon has been assessed. This was accomplished by statistically analyzing the breakdown characteristics of a large number of MOS capacitor structures, which had been fabricated in various ways. Although the results of this investigation are only qualitative, they clearly demonstrate that the effective breakdown strength of these films is strongly dependent on: purity, structural perfection and thickness; the presence of a passivating phosphosilicate glass layer; the presence and reactivity of the metal electrode; and, the duration of the post‐ metallization heat treatment. The morphology of certain micron‐size defects which develop in the MOS structure during annealing is described in some detail, since these faults are apparently responsible for oxide shorting in some instances.

The observation of dissociated dislocations in silicon

Abstract: The ‘weak-beam’ technique of Cockayne, Ray and Whelan (1969) for imaging dislocations in the electron microscope has been applied to dislocations in silicon. These are shown to be dissociated into partial dislocations, the dissociation width corresponding to a stacking-fault energy of about 55 erg cm−2.

Silica polishing compositions having a reduced tendency to scratch silicon and germanium surfaces

Abstract: Alkaline aqueous silica polishing compositions are provided, having a reduced tendency to scratch silicon and germanium surfaces, such as single crystal wafers polished for use in semiconductors. The polishing compositions comprise silica as the polishing agent, and a water-soluble cellulose ether, and are used with water.