Showing papers on "Silicon oxide published in 1990"

Growth of native oxide on a silicon surface

Abstract: The control factors controlling the growth of native silicon oxide on silicon (Si) surfaces have been identified. The coexistence of oxygen and water or moisture is required for growth of native oxide both in air and in ultrapure water at room temperature. Layer‐by‐layer growth of native oxide films occurs on Si surfaces exposed to air. Growth of native oxides on n‐Si in ultrapure water is described by a parabolic law, while the native oxide film thickness on n +‐Si in ultrapure water saturates at 10 A. The native oxide growth on n‐Si in ultrapure water is continuously accompanied by a dissolution of Si into the water and degrades the atomic flatness at the oxide‐Si interface, producing a rough oxide surface. A dissolution of Si into the water has not been observed for the Si wafer having surface covered by the native oxide grown in air. Native oxides grown in air and in ultrapure de‐ionized water have been demonstrated experimentally to exhibit remarkable differences such as contact angles of ultrapure waterdrops and chemical binding energy. These chemical bond structures for native oxide filmsgrown in air and in ultrapure water are also discussed.

Silicon Dioxide Deposition by Atmospheric Pressure and Low‐Temperature CVD Using TEOS and Ozone

Abstract: We report characteristics of the film deposited by an atmospheric pressure and low‐temperature CVD process using TEOS and ozone. Nondoped silicon oxide was deposited on thermally grown oxide, silicon, and aluminum steps. The film surface was very smooth even on aluminum lines and step coverage of the films changed from isotropic to flow shape with ozone concentration increase. This is one of the largest advantages of this CVD technology and is promising for advanced VLSI device fabrication. The film has tensile stress of less than , typically , low enough to fabricate VLSI devices. Film shrinkage was 5% in the film deposited at the higher ozone concentration when annealed at 950°C, which was comparable to that of the conventionally deposited films. The largest thickness without any cracks varied depending on deposition conditions. A thickness of 2 μm without cracks was obtained at 400°C and 0.1 μm/min deposition rate with an ozone concentration of 4.8%. Particle generation was very low and the number of particles of more than 0.3 μm were less than 20 on a 6 in. diam wafer.

Study of sidewall passivation and microscopic silicon roughness phenomena in chlorine‐based reactive ion etching of silicon trenches

Abstract: Sidewall passivation layers produced in the formation of Si trenches by HCl/O2/BCl3 reactive ion etching have been characterized by angle‐resolved x‐ray photoemission measurements and secondary electron microscopy. Electron‐shading effects observed at grazing electron emission angles and electrostatic charging of insulating portions have been used to differentiate photoemission contribution from (i) the trench sidewall film (moderately insulating), (ii) the oxide mask (highly insulating), and (iii) the Si trench bottom (conductive). The sidewall passivation film for this process is found to be a silicon oxide. Only minor amounts of chlorine are incorporated in this film. The thickness of the sidewall passivation layer depends on the width of the Si trench and ranges from ≂0.1 μm for narrow trenches to ≂0.7 μm for wide Si trenches for our conditions. The Si taper formed in this trench etching process is produced by the simultaneous formation of the sidewall film which protects the underlying Si from etchin...

Silica to Silicon: Key Carbothermic Reactions and Kinetics

Abstract: The primary carbothermic reactions for the reduction of silica to produce silicon were defined and the reaction kinetics were determined. Most possible reactions between silicon oxide and carbon or carbon compounds were studied by a series of thermogravimetric analyses at temperatures up to 2000°C. Four key sequential reactions occur with SiC and SiO as intermediate reactants; two reactions involve SiO2 and two involve SiO. Reaction rate versus temperature, activation energy, and preexponential factors were determined for each of six reactions involving SiO2 or SiO. These kinetic studies show that SiO, when combined with either carbon or Sic, reacts in the gaseous state, and the sublimation of SiO is not the rate-limiting reaction for forming silicon.

A substrate for thin-film gas sensors in microelectronic technology

Abstract: A laboratory model of a substrate for a gas sensor based on semiconducting tin oxide and produced in microelectronic technology is described. The paper discusses not only the problems of miniaturization of these gas sensors but also important production processes, with the exception of the gas-sensitive layer. The whole chip has a size of 2.7 by 2.7 mm and an active area of only 0.45 by 0.45 mm. The power consumption at the operating temperature of 300°C is below 75 mW. The active area is supported by a thin (10 μm) membrane of silicon oxide and nitride; an outer silicon frame provides mechanical stability. The heater is made from a NiFe alloy. The tested samples are stable and prove that a miniaturized low-cost gas sensor is feasible.

Single anneal step process for forming titanium silicide on semiconductor wafer

Abstract: An improved process is disclosed for forming a conductive layer of titanium silicide on a silicon semiconductor wafer using a single annealing step which comprises the steps of forming a titanium layer over the wafer in a vacuum deposition chamber in the substantial absence of oxygen-bearing gases; transferring the titanium coated wafer to a sealed annealing chamber without substantially exposing the newly formed titanium layer to oxygen-bearing gases; and then annealing the titanium-coated silicon semiconductor wafer in a nitrogen-bearing atmosphere in the sealed annealing chamber at a first temperature of from about 500° C. to about 695° C., in the substantial absence of oxygen-bearing gases, to form a titanium silicide layer and a titanium nitride layer over the titanium silicide which inhibits migration of underlying silicon to the surface, and to react substantially all of the titanium overlying silicon oxide (SiO 2 ) regions of the wafer to form titanium nitride, and then raising the temperature to form a more stable phase of titanium silicide without risk of reaction between the silicon oxide and unreacted titanium thereon.

Two step process for forming void-free oxide layer over stepped surface of semiconductor wafer

Abstract: A two step process is disclosed for forming a silicon oxide layer over a stepped surface of a semiconductor wafer while inhibiting the formation of voids in the oxide layer which comprises depositing a layer of an oxide of silicon over a stepped surface of a semiconductor wafer in a CVD chamber by flowing into the chamber a gaseous mixture comprising a source of oxygen, a portion of which comprises O3, and tetraethylorthosilicate as the gaseous source of silicon while maintaining the pressure in the CVD chamber within a range of from about 250 Torr to about 760 Torr and then depositing a second layer of oxide over the first layer in a CVD chamber by flowing into the chamber a gaseous mixture comprising a source of oxygen, a portion of which comprises O3 ; and tetraethylorthosilicate as the gaseous source of silicon while maintaining the CVD chamber at a lower pressure than during the first deposition step.

Gas-phase selective etching of native oxide

Abstract: Gas-phase selective etching of native oxide film formed on a silicon surface is an essential requirement for ULSI process technologies. Ultraclear anhydrous hydrogen fluoride (AHF) gas and a corrosion-free system were developed for this etching process. The reaction mechanism of silicon oxide film with moistureless HF was investigated, and selective etching conditions were developed. The gas-phase selective etching of native oxide in an environment of strictly controlled AHF concentration in N/sub 2/ is described. >

Method of producing a thin silicon on insulator layer by wafer bonding and chemical thinning

Abstract: A method for forming a thin crystal layer of silicon on top of a insulating layer that is supported by a silicon wafer used for electronic device applications. Carbon ions are implanted in a silicon wafer in order to form an etch stop. Said wafer is bonded to a supporting wafer that has an insulating surface layer of silicon oxide or silicon nitride. The silicon substrate of the implanted wafer is removed using an alkaline etching solution or grinding and alkaline etching. The remaining carbon implanted layer forms the thin silicon layer.

Method of fabricating polysilicon emitters for solar cells

Abstract: Polysilicon contacts for silicon devices such as bipolar junction transistors and silicon solar cells are fabricated in a two step anneal process to improve contact resistance and emitter saturation current density. After a silicon oxide layer is formed on a surface of a silicon substrate, a plurality of openings are formed there through to expose a plurality of contact surfaces on the surface of the silicon substrate. A thin thermally grown silicon oxide layer is then formed on the contact surfaces after which an undoped layer of polysilicon material is formed over the silicon oxide layers. The structure is then annealed at approximately 1050° C. to break the thermally grown silicon oxide layer. Thereafter, a first layer of doped glass is formed over the silicon oxide surface and selectively etched to remove the first layer of glass from a first group of contact surfaces. A second layer of doped glass is then formed over the first group of contact surfaces and over the first layer of doped glass. Thereafter, the silicon substrate is annealed at a temperature of approximately 900° C. thereby driving in dopants from said first and second layers of glass into said polysilicon layer over said first and second groups of contact surfaces. Finally, the layers of glass are removed and the polysilicon layer is patterned to define first and second polysilicon contacts.

Growth of epitaxial PrO2 thin films on hydrogen terminated Si (111) by pulsed laser deposition

Abstract: A new epitaxial oxide, PrO2, has been grown on Si (111) by pulsed laser deposition. X‐ray diffraction shows that films are oriented with the PrO2[111] direction parallel to the substrate [111]. The full width at half maximum for the omega rocking curve on the PrO2 (222) peak is as low as 0.75°, while phi scans indicate in‐plane epitaxial alignment to better than one degree. In the best quality films, epitaxy is almost pure type‐b epitaxy which is characteristic of epitaxial CaF2 on Si. To achieve epitaxy, it is essential to remove the native silicon oxide from the substrate prior to film growth. This is done at room temperature using a wet‐chemical hydrogen‐termination procedure.

Copper silicide formation by rapid thermal processing and induced room‐temperature Si oxide growth

Abstract: The growth of copper silicide has been studied by rapid thermal processing (RTP) of 500 A of Cu on Si substrates. Interaction between the diffusing metal and Si starts at 250–300 °C. Annealing at higher temperatures yields complete silicidation to Cu3Si. This leads to strong modifications of the Auger line shapes of both Si and Cu. A plasmon peak located 20 eV below the main peak is the fingerprint in the Cu spectrum. Strong features at 80, 85.6, 89.2, and 93.2 eV as well as a 1 eV shift of the 90.4 eV peak appear in the Si L2,3VV spectrum. Whether for Cu films annealed in nitrogen or in vacuum, exposure of the silicide to air results in the growth of silicon oxide at room temperature and continues until the silicide layer is totally converted. This repeatable and controllable oxidation of silicon is accompanied by changes in resistivity and color reflecting the extent of the process. For Cu/CoSi2/Si structures, the cobalt silicide acts as a transport medium for the growth of the copper silicide and also ...

Silicon-Hydrogen Bonds in Silicon Native Oxides Formed during Wet Chemical Treatments

Abstract: Silicon-hydrogen bonds in silicon oxide films were detected for the first time by applying surface-sensitive X-ray photoelectron spectroscopy and were confirmed by measuring infrared absorption. The areal density of silicon-hydrogen bonds in native oxides formed in a hot solution of HNO3 is estimated to be nearly 2×1014 cm-2, and is much larger than that formed in a solution with a composition of NH4OH:H2O2:H2O=1:1.4:4.

Ink jet printhead having ionic passivation of electrical circuitry

Abstract: An improved ink jet printhead (10) is disclosed of the type having a plurality of parallel ink flow channels (20) which terminate with an ink droplet emitting nozzle (27), a heating element (34) with a cavitational protective layer thereover located in each channel, and MOS electronic circuitry monolithically integrated within the printhead for applying electrical pulses to the heating elements (34). The pulsed heating elements produce bubbles momentarily on the protective layer of the heating elements which expel ink droplets from the nozzles. The improvement is obtained by providing multi-layer ionic passivation of the MOS electronic circuitry which is exposable to the ink. This is accomplished through the deposition of a multi-layered, thin film insulative coating thereon consisting of a first layer of doped or undoped silicon dioxide having a thickness of 200 A to 2µm followed by a second layer of plasma nitride having a thickness of 1000 A to 3 µm. The silicon nitride is etched from the protective layers of the heating elements and electrical contact pads for external connection to electrical power so that the first layer of silicon oxide is exposed, followed by etching of the silicon oxide to remove it from the protective layer and contact pads. Thus, the MOS circuitry is protected from mobile ions in the ink while the cost effective fabrication of a printhead is maintained. In an alternate embodiment, the multi-layered ionic passivation comprises three thin film layers comprising polyimide interfacing with the ink, followed by silicon nitride, and doped or undoped silicon dioxide directly interfacing with the metallization.

White colored deodorizer and process for producing the same

Abstract: A white colored deodorizer comprising zinc oxide and at least one oxide selected from the group consisting of aluminium oxide and silicon oxide and a method for preparation of it are disclosed.

Selective silicon nitride plasma etching

Abstract: A two step method of etching a silicon nitride layer carrying a surface oxygen film from a substrate in a plasma reactor employs the steps of (1) a breakthrough step of employing a plasma of oxygen free etchant gases to break through and to remove the surface oxygen containing film from the surface of the silicon nitride layer, and (2) a main step of etching the newly exposed silicon nitride with etchant gases having high selectivity with respect to the silicon oxide underlying the silicon nitride. The plasma etching can be performed while employing magnetic-enhancement of the etching. The plasma etching is performed in a plasma reactor comprising a low pressure, single wafer tool. Plasma etching is performed while employing magnetic-enhancement of the etching. The etchant gases include a halide such as a bromide and a fluoride in the breakthrough step. The etchant gases include an oxygen and bromine containing gas in the main step.

Method of bonding together two bodies with silicon oxide and practically pure boron

Abstract: A method is set forth of bonding together two bodies (1, 2), according to which a first body (1) is provided with a flat surface (5) and the second body (2) is provided with a silicon oxide layer (4) with a flat surface (6), after which a connecting layer (7) containing boron is provided on at least one of the two flat surfaces. Subsequently, the two bodies (1, 2) are pressed together at elevated temperature, so that a borosilicate glass layer is formed. According to the invention, a layer of practically pure boron is used by way of connecting layer (7). Among the advantages of this is that the composition of the borosilicate glass layer is exclusively determined by the previously chosen layer thicknesses.

Radiation resistant passivation of silicon solar cells

Abstract: The interface of a silicon oxide passivation layer and a silicon substrate in a silicon solar cell is stabilized by covering the silicon oxide passivation layer with a layer of undoped or phosphorus doped polycrystalline silicon. A second layer of silicon oxide is formed by deposition on the surface of the phosphorus doped polycrystalline and enhances the anti-reflection characteristics of the composite structure.

Spatially-resolved X-ray Absorption Near-edge Spectroscopy of Silicon in Thin Silicon-oxide Films

Abstract: The electronic structure of oxide thin films on silicon single crystals has been measured with high spatial resolution by x-ray absorption near edge spectroscopy (XANES) using a photoelectron microscope and monochromatic synchrotron radiation. Native oxide overlayers on Si(100) and Si(111) crystals were studied at various stages during thermal desorption of the oxide. The spatial resolution capability of the microscope is used to perform selected-area XANES measurements of silicon and silicon oxides, which reveal for the first time the absorption characteristics of intermediate oxidation states of silicon (Si2+ and Si3+), and identify the spin-orbit splitting of the silicon 2p core-exciton structure in Si2+, Si3+, and SiO2. Our results confirm photoemission measurements which find Si2+ and Si3+ states existing at vertical interfaces between Si and SiO2. Unlike the photoemission spectra, however, selected-area XANES can resolve the spectroscopic signatures of these intermediate oxidation states in laterally inhomogeneous interfaces.

Thickness-Dependent Frequency Shift in Infrared Spectral Absorbance of Silicon Oxide Film on Silicon

Abstract: The spectral dependence of the refractive index n and extinction coefficient k of chemical-vapor-deposited (CVD) silicon oxide film on silicon wafer has been determined. The results are used to calculate spectral absorbances for 0.1-2 μm thick oxide films with unchanged structure. The dependence on thickness of the position of Si-O stretching (vM) has been investigated. The main factor influencing the frequency is the transmission factor at the air/film and film/substrate boundaries. In the limit of d → 0, vM corresponds to the maximum of the Im (e) function.

Water-Adsorbed States on Silicon and Silicon Oxide Surfaces Analyzed by using Heavy Water

Abstract: Water-adsorbed states on Si, native oxide and thermal oxide surfaces are investigated by means of thermal desorption spectroscopy. D2O is used to detect the water signals from these surfaces, which are separated from background H2O signals. The water desorption is 1/10 less than the hydrogen desorption. The amount of hydrogen adsorbed is largest on the Si surface and smallest on the thermal oxide surface. Four types of binding states of hydrogen are assigned to be SiO-H and Si-H on the silicon surface, Si-H in the native oxide, and Si-H in the interface between the native oxide and the silicon substrate.

Method of depositing an insulating film and a focusing ion beam apparatus

Abstract: Disclosed is a focusing ion beam apparatus, comprising an ion source, focusing and deflecting means for focusing and deflecting an ion beam obtained by the ion source, and a plurality of gas introducing means for a plurality of gases to be supplied onto the surface of a sample to deposit an insulating film. According to the apparatus, a silicon compound gas and a gas mainly consisting of an element other than silicon as a plurality of the gases are supplied onto the surface of the sample, then the ion beam obtained from the ion source is irradiated onto the gases. Thereby, the gases are decomposed so that an insulating film consisting of a silicon oxide or a silicon nitride is deposited on a desired oxide or a silicon nitride is deposited on a desired position of the surface of the sample.

Process for the manufacture of deposition films and apparatus therefor

Abstract: An apparatus for use in a process for the substantially continuous manufacture of a silicon oxide deposition film by evaporating a deposition material composed mainly of a combination of silicon and silicon oxide or silicon oxide alone by heating the material to continuously form a deposition layer composed mainly of silicon oxide and having a thickness of from 100 to 3,000 Å on the surface of a travelling flexible plastic film. The apparatus comprises a vacuum chamber and, within the vacuum chamber, a means to allow a flexible plastic film to travel continuously, a heat evaporation member having a means to hold a shaped deposition material and a means to evaporate the shaped deposition material, the holding means having a supply port for the shaped deposition material, an outlet for evaporation residue and an opening for evaporation of the deposition material, and the means to substantially continuously supply the shaped deposition material being connected to the supply port to the heat evaporation member and to substantially continuously discharge evaporation residue from the heat evaporation member.

Surface contamination and damage from CF 4 and SF 6 reactive ion etching of silicon oxide on gallium arsenide

Abstract: Two reactive ion etchants, CF4 and SF6, have been compared in terms of plasma characteristics, silicon oxide etch characteristics, extent of RIE damage, and formation of barrier layers on a GaAs surface after oxide etch. It was found that higher etch rates with lower plasma-induced dc bias can be achieved with SF6 plasma relative to CF4 plasma and that this correlates with higher atomic fluorine concentration in SF6 plasma. RIE damage, measured by loss of sheet conductance in a thin highly-doped GaAs layer, could be modelled as a region of deep acceptors at a high concentration in the conductive layer. By relating the sheet conductance change to the modelled damaged layer thickness, it was found that the RIE-damaged thickness from both CF4 and SF6 plasmas had the same linear relation to plasma dc bias. Barriers to subsequent GaAs RIE were created during oxide overetch at the GaAs surface. The barriers were identified by XPS as ∼20 A of GaF3 for CF4 plasma and ∼30 A of GaF3 on top of AsxSy for SF6 plasma. Ellipsometry was used to routinely determine the presence or absence of the barriers which could be removed in dilute ammonia.

Quantitative infrared study of ultrathin MIS structures by grazing internal reflection

Abstract: A very sensitive reflection technique well suited for infrared investigations of thin MIS structures is introduced. With this technique a nearly saturating reflectance drop from the Si-O vibration of a 1.3 nm oxide on silicon within a MIS structure was measured at 1240 cm−1. The analytic discussion of the sensitivity amplification of this technique shows that for silicon oxide a sensitivity amplification by a factor of 600 per reflection is feasible over the sensitivity of a transmission measurement. The analytic discussion is verified experimentally for the case of 12 nm silicon nitride film. A method that allows one to determine bond concentrations of thin films within MIS structures is given and tested for the case of hydrogen bonds in silicon nitride.

Manufacture of semiconductor device

Abstract: PURPOSE:To make an oxidation speed slow and to form a thermal oxide film with good controllability by a method wherein an undoped polysilicon film is formed on the surface of a first electrode composed of polysilicon into which impurities have been introduced and, after that, it is thermally oxidized. CONSTITUTION:A silicon oxide film 2 is formed on the surface of a silicon substrate 1; and a polysilicon film is grown by using an LPCVD method; ions of impurities are implanted; after that, a first electrode 3 is formed by a photoetching operation. Then, an undoped polysilicon film 4 is formed on the surface of the first electrode 3; a thermal oxidation operation is executed; and a thin silicon oxide film 5 is formed. Then, a silicon nitride film 6 is formed by an LPCVD method or the like; a thermal oxidation operation is executed; a thin silicon oxide film 7 is formed; a polysilicon film to be used as a second electrode is deposited; a doping operation is executed; then, a photoetching operation is executed; and the second electrode 8 is formed. Thereby, an oxidation speed is made slow, and the thin thermal oxide film 5 can be formed with good controllability.