Abstract: A Czochralski method of producing a single crystal silicon ingot having a uniform thermal history. In the process, the power supplied to the side heater is maintained substantially constant throughout the growth of the main body and end-cone of the ingot, while power supplied to a bottom heater is gradually increased during the growth of the second half of the main body and the end-cone. The present process enables an ingot to be obtained which yields wafers having fewer light point defects in excess of about 0.2 microns, while having improved gate oxide integrity.

Abstract: There are provided a CZ system for manufacturing a single-crystal ingot, which produces a perfect crystal with good reproducibility through growth of a single-crystal ingot, as well as a method of manufacturing the single-crystal ingot. A system of manufacturing a single-crystal ingot by pulling a single-crystal ingot from molten raw material by means of a Czochralski technique, the system including measurement means for measuring the distance between the level of molten raw material and the bottom of a heat-shielding member. On the basis of the thus-measured distance, the temperature gradient of area G1 of the single-crystal pulled silicon ingot is controlled so as to produce a perfect crystal with good reproducibility, by means of controlling any factor for pulling a single-crystal silicon ingot selected from the group comprising the amount of heat applied to silicon melt, the level of silicon melt, and the pull rate of a single-crystal silicon ingot.

Abstract: The high purity C/C composite formed by graphitizing a molded member packed with carbon fibers and carbon material of a matrix. The carbon fibers are high purified under halogen gas atmosphere. The purified carbon fibers are molded into the desired shape on a tool or in die with infiltrating the matrix. The molded member packed with carbon fibers and carbon material of the matrix are either independently or simultaneously graphitized and then high-purification under halogen gas atmosphere. According to the present process, the metal impurities can be very low contents.

Abstract: In pulling a single crystal by CZ method, stable pulling up is carried out in a pulling rate as fast as possible while a crystal deformation is controlled to an aimed value and density of grown-in defects is suppressed to a value below an upper limit value. As an index of deformation of the single crystal from a perfect circle, the aimed value of the crystal deformation is previously determined. The upper limit value of a pulling rate necessary to suppress a defect density to an allowable range is previously calculated from distribution of grown-in defects in the crystal section, the single crystal is pulled up according to a predetermined pulling rate, and then deviation of the achieved value from the aimed value of the crystal deformation in pulling is calculated. The deviation is converted to a correction of the pulling rate. This correction is added to a set value of the pulling rate in the pulling and the result is used as a temporary set value of the pulling rate in the next pulling.

Abstract: The present invention relates to single crystal silicon, in ingot or wafer form, which contains an axially symmetric region which is free of agglomerated intrinsic point defects, and a process for the preparation thereof. The process including controlling growth conditions, such as growth velocity, v, instantaneous axial temperature gradient, G0, and the cooling rate, within a range of temperatures at which silicon self-interstitials are mobile, in order to prevent the formation of these agglomerated defects. The control of G0 is accomplished by controlling heat transfer at the melt/solid interface.

Abstract: The present invention relates a process for the preparation of single crystal silicon, which contains an axially symmetric region which is free of agglomerated intrinsic point defects. The process for growing the single crystal silicon including controlling the ratio v/G0, where v is the growth velocity and G0 is the average axial temperature gradient during the growth of a constant diameter portion of the crystal over a temperature range from solidification to a temperature of no less than about 1325° C., and a cooling rate of the crystal from a solidification temperature to about 1,050° C., in order to cause the formation of an axially symmetrical segment which is substantially free of agglomerated intrinsic point defects. The control of V/G0 accomplished by controlling heat transfer at the melt/solid interface.

Abstract: A process for the preparation of a silicon single ingot in accordance with the Czochralski method. The process for growing the single crystal silicon ingot comprises controlling (i) a growth velocity, v, (ii) an average axial temperature gradient, G0, during the growth of a constant diameter portion of the crystal over a temperature range from solidification to a temperature of no less than about 1325° C. to initially produce in the constant diameter portion of the ingot a series of predominant intrinsic point defects including vacancy dominated regions and silicon self interstitial dominated regions, alternating along the axis, and cooling the regions from the temperature of solidification at a rate which allows silicon self-interstitial atoms to diffuse radially to the lateral surface and to diffuse axially to vacancy dominated regions to reduce the concentration intrinsic point defects in each region.

Abstract: The high quality silicon wafer of large diameter is invented by mainly paying attention to the particles ascribed to the crystal and the wafer is optimal for manufacturing ultra highly integrated devices. The silicon wafer is of diameter of 300 mm and larger sliced from a single-crystal silicon ingot pulled by CZ method, the surface is mirror-polished and cleaned with ammonia based cleaning solution, and the number of particles of 0.083 &mgr;m and larger in size detected on its main surface is 120 and smaller and/or particles of 0.090 &mgr;m and larger in size is smaller than 80.

Abstract: The present invention relates to a single crystalline silicon ingot by Czochralski method and, more particularly, to a single crystalline silicon ingot, a wafer and a method of producing a single crystalline silicon ingot in which an oxidation-induced stacking fault ring is distributed widely and which has an agglomerated vacancy point defect area of low density wherein DSOD exists only, without FPD. Accordingly, an oxidation-induced stacking fault area having a micro-vacancy defect area of low density is distributed widely from the ingot edge to the ingot center in a single crystalline silicon ingot and a wafer fabricated by the present invention. As the micro-vacancy defect area has no FPD but may have DSOD, a coarsely agglomerated vacancy point defect area in which FPD and DSOD cohabit is shrunken or even eliminated. Therefore, the present invention improves the product quality as well as device yield.

Abstract: The present invention relates to a single crystalline silicon ingot, a single crystalline wafer, and a producing method thereof in accordance with the Czochralski method which enables reduction of a large defect area while increasing a micro-vacancy defect area in an agglomerated vacancy point area, which is the area between a central axis and an oxidation-induced stacking fault ring, by providing uniform conditions of crystal ingot growth and cooling and by adjusting a pulling rate for growing an ingot to grow, thus the oxidation-induced stacking fault ring exists only at an edge of the ingot radius.

Abstract: A process for heat-treating a single crystal silicon wafer to influence the precipitation behavior of oxygen in the wafer in a subsequent thermal processing step. The wafer has a front surface, a back surface, a central plane between the front and back surfaces, and a sink for crystal lattice vacancies at the front surface. In the process, the wafer is subjected to a heat-treatment to form crystal lattice vacancies, the vacancies being formed in the bulk of the silicon. The wafer is then cooled from the temperature of said heat treatment at a rate which allows some, but not all, of the crystal lattice vacancies to diffuse to the crystal lattice vacancy sink to produce a wafer having a vacancy concentration profile in which the peak density is at or near the central plane with the concentration generally decreasing in the direction of the front surface of the wafer.

Abstract: Methods for producing doped polycrystalline semiconductors and for producing doped monocrystalline semiconductors from predoped monocrystalline and polycrystalline semiconductors. The methods for producing doped polycrystalline semiconductors may include (1) providing a reactor for chemical vapor deposition, (2) creating a vapor within the reactor that includes a silicon compound and a preselected dopant, and (3) providing a substrate, exposed to the vapor, onto which the silicon and the dopant in the vapor are deposited to form doped polycrystalline silicon. The methods for producing doped monocrystalline semiconductors may include (1) selecting a first amount of a first semiconductor, the first semiconductor having a first concentration of the dopant, (2) selecting a second amount of a second semiconductor, and (3) using the first and second amounts to grow a monocrystalline semiconductor having a preselected concentration of the dopant.

Abstract: A method for producing a silicon single crystal, wherein, when a silicon single crystal is grown by the Czochralski method, the crystal is pulled with such conditions as present in a region defined by a boundary between a V-rich region and an N-region and a boundary between an N-region and an I-rich region in a defect distribution chart showing defect distribution which is plotted with D [mm] as abscissa and F/G [mm2/° C.·min] as ordinate, wherein D represents a distance between center of the crystal and periphery of the crystal, F/G [mm/min] represents a pulling rate and G [° C./mm] represents an average temperature gradient along the crystal pulling axis direction in the temperature range of from the melting point of silicon to 1400° C., and time required for crystal temperature to pass through the temperature region of from 900° C. to 600° C.

Abstract: A single-crystal silicon substrate is provided, which makes it possible to accurately control the concentration and profile of an introduced impurity. This silicon substrate is comprised of a single-crystal Si base layer and a single-crystal Si low oxygen-concentration layer formed on the base layer. The base layer has a first oxygen concentration and the low oxygen-concentration layer has a second oxygen concentration lower than the first oxygen concentration. This silicon substrate is fabricated by (a) growing a single-crystal Si epitaxial layer on the main surface of a single-crystal Si base material in such a way that the epitaxial layer has a second oxygen concentration lower than of the first oxygen concentration, or (b) heat-treating a single-crystal Si base material to cause outward diffusion of oxygen existing in the base material through the main surface thereof, thereby forming a low oxygen-concentration layer extending along the main surface of the base material in the base material.

Abstract: The present invention is directed to a set of epitaxial silicon wafers assembled in a wafer cassette, boat or other wafer carrier. Each wafer comprises a single crystal silicon substrate having an axially symmetric region in which silicon self-interstitials are the predominant intrinsic point defect and which is substantially free of agglomerated defects, and an epitaxial layer which is deposited upon a surface of the substrate and which is substantially free of grown-in defects caused by the presence of agglomerated silicon self-interstitial defects on the substrate surface upon which the epitaxial layer is deposited.

Abstract: A continuous oxidation process and apparatus for using the same are disclosed. During growth of a semiconductor crystal an oxygen-containing gas is continuously injected into the crystal pulling apparatus in an exhaust tunnel downstream from the hot zone to continuously oxidize hypostoichiometric silicon dioxide, silicon vapor, and silicon monoxide produced in the hot zone during the crystal growth so as to minimize or eliminate the possibility of rapid over-pressurization of the apparatus upon exposure to the atmosphere.

Abstract: This invention is directed to a novel a single crystal silicon wafer. In one embodiment, this wafer comprises: (a) two major generally parallel surfaces (i.e., the front and back surfaces); (b) a central plane between and parallel to the front and back surfaces; (c) a front surface layer which comprises the region of the wafer extending a distance of at least about 10 &mgr;m from the front surface toward the central plane; and (d) a bulk layer which comprises the region of the wafer extending from the central plane to the front surface layer.

Abstract: A method of fabricating a silicon single crystal ingot and a method of fabricating a silicon wafer using the ingot, characterized in that: the method is structured in such a manner that the silicon single crystal ingot is pulled up from the silicon fused liquid 7 in which nitrogen N and carbon C are doped in polycrystalline silicon, by using the Czochralski method, and its nitrogen density is 1×1013-5×1015 atoms/cm3, and the carbon density is 5×1015-3×1016 atoms/cm3.

Abstract: The invention relates to the field of electronics and can be used in acoustic electronic frequency-selective devices in surface acoustic waves (SAW) and volumetric acoustic waves. The purpose of the invention is the formulation of an industrial process to develop stoichiometrically structured monocrystals of lanthalum gallium silicate, of no less than 75 mm in diameter and greater than 3,5 kg in weight, along a direction of <01.1>±3°. The discs are cut out at a 90° angle with respect to the lengthwise axis, thereby ensuring that the value of the frequency temperature coefficient is zero.

Abstract: A process for growing a single crystal silicon ingot having an axially symmetric region substantially tree of agglomerated intrinsic point defects. The ingot is grown generally in accordance with the Czochralski method; however, the manner by which the ingot is cooled from the temperature of solidification to a temperature which is in excess of about 900° C. is controlled to allow for the diffusion of intrinsic point defects, Such that agglomerated defects do not form in this axially symmetric region. Accordingly, the ratio v/G0 is allowed to vary axially within this region, due to changes in v or G0, between a minimum and maximum value by at least 5%.

Abstract: The present invention relates to silicon with a high oxygen content and, at the same time, a high density of crystal lattice dislocations, and to its production. This silicon may be used in photovoltaics. Solar cells which are based on the material according to the invention exhibit high levels of efficiency despite the high oxygen content.

Abstract: The present invention relates to single crystal silicon, in ingot or wafer form, which contains an axially symmetric region which is free of agglomerated intrinsic point defects, and a process for the preparation thereof. The process comprises controlling growth conditions, such as growth velocity, v, instantaneous axial temperature gradient, G0, and the cooling rate, within a range of temperatures at which silicon self-interstitials are mobile, in order to prevent the formation of these agglomerated defects. In ingot form, the axially symmetric region has a width, as measured from the circumferential edge of the ingot radially toward the central axis, which is at least about 30% the length of the radius of the ingot. The axially symmetric region additionally has a length, as measured along the central axis, which is at least about 20% the length of the constant diameter portion of the ingot.

Abstract: The present invention is directed to a set of epitaxial silicon wafers assembled in a wafer cassette, boat or other wafer carrier. Each wafer comprises a single crystal silicon substrate having an axially symmetric region in which silicon self-interstitials are the predominant intrinsic point defect and which is substantially free of agglomerated defects, and an epitaxial layer which is deposited upon a surface of the substrate and which is substantially free of grown-in defects caused by the presence of agglomerated silicon self-interstitial defects on the substrate surface upon which the epitaxial layer is deposited.

Abstract: There is disclosed a method for producing a silicon single crystal wafer wherein a silicon single crystal is grown in accordance with the CZ method with doping nitrogen in an N-region in a defect distribution chart which shows a defect distribution in which the horizontal axis represents a radial distance D (mm) from the center of the crystal and the vertical axis represent a value of F/G (mm2/° C.·min), where F is a pulling rate (mm/min) of the single crystal, and G is an average intra-crystal temperature gradient(° C./mm) along the pulling direction within a temperature range of the melting point of silicon to 1400° C. There can be provided a method of producing a silicon single crystal wafer consisting of N-region where neither V-rich region nor I-rich region is present in the entire surface of the crystal by CZ method, under the condition that can be controlled easily in a wide range, in high yield, and in high productivity.

Abstract: The objective of this invention is to provide a manufacturing method wherewith optimally low-COP substrates can be efficiently manufactured for epitaxial wafers in order to obtain high epitaxial surface quality that will not have an adverse effect on device characteristics. A phenomenon was discovered whereby COPs are eliminated by solution annealing or flattening when epitaxial films are formed on wafers wherein the density of grown-in defects (COPs) with a size of 0.130 &mgr;m or larger is 0.03 defects/cm2 or lower, the use of which phenomenon is characteristic of the invention.

Abstract: The present invention relates to single crystal silicon, in ingot or wafer form, which contains an axially symmetric region which is free of agglomerated intrinsic point defects, and a process for the preparation thereof. The process for growing the single crystal silicon ingot comprises controlling (i) a growth velocity, v, (ii) an average axial temperature gradient, G0, during the growth of a constant diameter portion of the crystal over a temperature range from solidification to a temperature of no less than about 1325° C., and (iii) a cooling rate of the crystal from a solidification temperature to about 1,050° C., in order to cause the formation of an axially symmetrical segment which is substantially free of agglomerated intrinsic point defects.

Abstract: A process for producing a silicon single crystal has the crystal being pulled using the Czochralski method while being doped with oxygen and nitrogen. The single crystal is doped with oxygen at a concentration of less than 6.5*1017 atoms cm−3 and with nitrogen at a concentration of more than 5*1013 atoms cm−3 while the single crystal is being pulled. Another process is for producing a single crystal from a silicon melt, in which the single crystal is doped with nitrogen and the single crystal is pulled at a rate V, an axial temperature gradient G(r) being set up at the interface of the single crystal and the melt, in which the ratio V/G(r) in the radial direction is at least partially less than 1.3*10−3cm2min−1 K−1.

Abstract: A method of determining oxygen precipitation behavior in a silicon monocrystal through use of a programmed computer. According to this method, an initial oxygen concentration of a silicon monocrystal, an impurity concentration or resistivity of the silicon monocrystal, and conditions of heat treatment performed on the silicon monocrystal are input, and an amount of precipitated oxygen and bulk defect density of the silicon monocrystal after the heat treatment are calculated based on the input data. The method enables quick, simple, and accurate determination of an amount of precipitated oxygen and bulk defect density in silicon during or after heat treatment.

Abstract: There is disclosed a method for producing a silicon single crystal by growing the silicon single crystal by the Czochralski method, characterized in that the crystal is pulled at a pulling rate [mm/min] within a range of from V1 to V1+0.062×G while the crystal is doped with nitrogen during the growing, where G [K/mm] represents an average temperature gradient along the crystal growing direction, which is for a temperature range of from the melting point of silicon to 1400° C., and provided in an apparatus used for the crystal growing, and V1 [mm/min] represents a pulling rate at which an OSF ring disappears at the center of the crystal when the crystal is pulled by gradually decreasing the pulling rate.

Abstract: A liquid phase deposition method of mass producing substantially uniform silicon dioxide films on wafers by forming wafer sets from at least four wafers. The wafer sets are placed in a slotted polytetrafluroethylene polymer boat wherein a proper and short distance between the front surface of a wafer and another surface is created. Finally, a substantially uniform silicon dioxide film is deposited on the wafer surfaces by contacting the wafer sets with an aqueous supersaturated silicon dioxide solution comprising a mixture of hydrofluosilicic acid and boric acid.

Abstract: There is disclosed a method for producing a silicon single crystal in accordance with the Czochralski method wherein a crystal is pulled with controlling a temperature in a furnace so that &Dgr;G may be 0 or a negative value, where &Dgr;G is a difference between the temperature gradient Gc (° C./mm) at the center of a crystal and the temperature gradient Ge (° C./mm) at the circumferential portion of the crystal, namely &Dgr;G=(Ge−Gc), wherein G is a temperature gradient in the vicinity of a solid-liquid interface of a crystal from the melting point of silicon to 1400° C.

Abstract: In a conventional method, it is difficult to reject a stray light component with certainty, so that it is difficult to accurately measure the temperature of the melt surface. Since a temperature measuring device and a computing means are expensive, the cost of the measurement tends to be high. Modifications to an existing apparatus for pulling a single crystal are required, which is an inconvenience. In order to solve the above problems, a CCD camera is used for detecting the radiation light luminance distribution of the melt surface, the minimum radiation light luminance Lmin is determined based on the radiation light luminance distribution data measured using the CCD camera, and the temperature TS of the melt surface within an apparatus for pulling a single crystal is computed based on the minimum radiation light luminance Lmin.

Abstract: This invention provides a method for manufacturing silicon single crystals. The method is capable of eliminating void defects existing in deep regions of a silicon single crystal despite the size of the silicon single crystal. The silicon single crystals according to this invention are pulled the radius of a ring-shaped oxidation induced stacking fault (OSF ring) of a wafer is larger than half the radius of the wafer during the process of thermal oxidation treatment.

Abstract: This invention provides a method and a apparatus capable of manufacturing single crystals with an oxygen density of less than 12×1017 atoms/cm3 or less than 10×1017 atoms/cm3, and wherein the oxygen density of the single crystal produced is uniformly distributed along its longitudinal axis. The electrical power inputted into the main heater 6 surrounding the quartz crucible 4 and the top heater 9 shaped like a reverse frustrated cone and disposed above the quartz crucible 4, is controlled to keep the temperature of the melt 5 in a preset range during the process of pulling up the single crystal silicon 10. When combining the main heater 6 and the top heater 9, the heat emitted from the main heater 6 can be kept small, and the heat load on the quartz crucible 4 and the amount of oxygen released from the quartz crucible 4 and dissloved into melt 5 can be reduced.

Abstract: A method for producing a silicon monocrystal according to Czochralski method characterized in growing crystal with controlling a pulling rate between a transition pulling rate Pc at which there is caused a transition from a region where excess vacancies are present, but grown-in defect is not present to a region where excess interstitial silicon atoms are present, but an agglomerate thereof is not present, and a transition pulling rate Pi from a region where excess interstitial silicon atoms are present, but an agglomerate thereof is not present to a region where an agglomerate of interstitial silicon atoms is present. There are provided a method for producing a silicon monocrystal having no defect through the whole area of the wafer and having high quality wherein a deviation of amount of precipitated oxygen is small by pulling a crystal with controlling a pulling rate P as a general and interoperable valuable, and the silicon monocrystal produced thereby.

Abstract: A method for producing a silicon single crystal by a Czochralski method comprises bringing a seed crystal into contact with a melt, performing a necking operation, and growing a single crystal ingot, wherein concentration of interstitial oxygen incorporated during the necking operation is 1 ppma (JEIDA) or more. The rate of success in making dislocation-free crystals is improved in a seeding method in which a necking operation is performed.

Abstract: In a Czochralski method for producing a silicon single crystal by growing the crystal, the pulling rate of the single crystal is gradually increased during formation of a tail part after formation of a predetermined or constant diameter part of the single crystal. The length t of the tail part is defined to be a or more, where a represents a distance from the tip end of the tail part to a position of an extraordinary oxygen precipitation area when the tail part is formed after the predetermined or constant diameter part is grown. Productivity and yield of the silicon single crystal are improved by preventing rapid change in temperature while the single crystal is separated from the melt in the tailing process, to suppress generation of an area where the amount of precipitated oxygen is extraordinarily large and an OSF ring due to rapid increase in temperature when the tail part is formed, in the predetermined or constant diameter part near the tail part.

Abstract: A single crystal is grown in accordance with a Czochralski method such that the time for passing through a temperature zone of 1150-1080.degree. C. is 20 minutes or less, or such that the length of a portion of the single crystal corresponding to the temperature zone of 1150-1080.degree. C. in the temperature distribution is 2.0 cm or less. Alternatively, the single crystal is grown such that the time for passing through a temperature zone of 1250-1200.degree. C. is 20 minutes or less, or such that the length of a portion of the single crystal corresponding to the temperature zone of 1250-1200.degree. C. in the temperature distribution is 2.0 cm or less. This method decreases both the density and size of so-called grown-in defects such as FPD (100 defects/cm.sup.2 or less), LSTD, and COP (10 defects/cm.sup.2 or less) to thereby enable efficient production of a single crystal having an excellent good chip yield (80% or greater) in terms of oxide dielectric breakdown voltage characteristics.

Abstract: In a method for producing a silicon single crystal wafer, a silicon single crystal is grown in accordance with the Czochralski method such that the F/G value becomes 0.112-0.142 mm.sup.2 /.degree. C..multidot.min at the center of the crystal, where F is a pulling rate (mm/min) of the single crystal, and G is an average intra-crystal temperature gradient (.degree. C./mm) along the pulling direction within a temperature range of the melting point of silicon to 1400.degree. C. Additionally, the single crystal is pulled such that the interstitial oxygen concentration becomes less than 24 ppma, or the time required to pass through a temperature zone of 1050-850.degree. C. within the crystal is controlled to become 140 minutes or less. The method allows production of silicon single crystal wafers in which neither FPDs nor L/D defects exist on the wafer surface, which therefore has an extremely low defect density, and whose entire surface is usable.

Abstract: A silicon single crystal wafer having good device characteristics can be manufactured according to the Czochralski method without formation of any dislocation cluster within a crystal surface. Where a silicon single crystal having an oxygen concentration of less than 8.5.times.10.sup.17 atoms/cm.sup.3 (ASTM F1188-88) is manufactured, a radius of a latent zone of oxidation induced stacking defects ring-likely-distributed in the crystal surface is made within a range of 70% to 0% of a crystal radius, and a value of V/G (mm.sup.2 /.degree. C..multidot.minute) is controlled at a predetermined critical value or over at radial positions except an outermost periphery of the crystal when a pulling rate is taken as V (mm/minute), and a crystalline temperature gradient along the pulling axis is taken as G (.degree. C./mm). On the other hand, when a silicon single crystal having an oxygen concentration of not less than 8.5.times.10.sup.17 atoms/cm.sup.

Abstract: A method of growing a crystalline ingot, such as a dislocation free ("DF") crystalline ingot, is provided including the steps of providing a melt having an at least partially solidified surface. Next, a seed crystal is brought into contact with the solidified portion of the surface of the melt and the temperature of the seed crystal is permitted to stabilize. Once the temperature of the seed crystal has stabilized, the temperature of the melt is raised to completely liquify the melt. While the temperature of the melt is being raised, the seed crystal is maintained in contact with the melt thereby reducing thermal shock in the seed crystal by permitting the seed crystal to gradually warm with the liquidation of the melt. Once the melt is completely liquified, the seed crystal is withdrawn from the melt to thereby grow a DF crystalline ingot.

Abstract: A method and apparatus for producing crystals by the Czochralski method whereby the thermal history during crystal growth according to the CZ method can be controlled with ease and accuracy. The apparatus comprises a crucible for receiving a raw material, a heater for heating and melting the raw material, and a heat insulating cylinder disposed so as to surround the crucible and the heater, wherein a portion of the heat insulating cylinder that is located above an upper end of the heater is so configured that its inner diameter is larger than the outer diameter of the heater at its lower end, and that its inner diameter at its upper end is equal to or less than the inner diameter of the heater while its outer diameter is equal to or greater than the outer diameter of the heater. This apparatus is used to produce crystals and to control the temperature distribution inside the crystal producing apparatus or the thermal history of crystals.

Abstract: the present invention provides an improved method and apparatus for doping silicon and other crystals made by the Czochralski process wherein the surface of the melt is partially enclosed or covered in order to capture the dopant vapors and improve the efficiency with which they are dissolved in the melt. In accordance with the invention the dopant is suspended in a vapor retention vessel such as a quartz bell jar which is suspended above the melt so that the heat from the melt causes the dopant to vaporize. In accordance with the invention, an annular baffle is provided around the mouth of the vessel or the rim of the crucible containing the melt such that the amount of uncovered open area on the surface of the melt is reduced and the dopant vapor is retained in contact with the surface of the melt such that it dissolves more efficiently in the melt.

Abstract: In the pulling of a single crystal, hitherto, it is difficult to reduce the OSF density while the deformation rate is held down within the tolerance, so that it is difficult to improve the quality and productivity. In the present invention, a deviation from a true circle in each part of a single crystal S.sub.n-1 which was pulled in the preceding batch is found and the pulling speed pattern f.sub.pn-1 (L.sub.1) in the preceding batch is updated (f.sub.pn (L.sub.1)) before a single crystal S.sub.n is pulled, in order to pull the single crystal as fast as possible so that the OSF density is small while the deviation is within the tolerance.

Abstract: A method for producing a silicon single crystal in accordance with the Czochralski method. The single crystal is grown in an N.sub.2 (V) region where a large amount of precipitated oxygen and which is located within an N region located outside an OSF ring region, or is grown in a region including the OSF ring region, N.sub.1 (V) and N.sub.2 (V) regions located inside and outside the OSF ring region, in a defect distribution chart which shows a defect distribution in which the horizontal axis represents a radial distance D (mm) from the center of the crystal and the vertical axis represents a value of F/G (mm.sup.2 /.degree.C..multidot.min), where F is a pulling rate (mm/min) of the single crystal, and G is an average intra-crystal temperature gradient (.degree.C./mm) along the pulling direction within a temperature range of the melting point of silicon to 1400.degree. C.

Abstract: A continuous oxidation process and apparatus for using the same are disclosed. During growth of a semiconductor crystal an oxygen-containing gas is continuously injected into the crystal pulling apparatus in an exhaust tunnel downstream from the hot zone to continuously oxidize hypostoichiometric silicon dioxide, silicon vapor, and silicon monoxide produced in the hot zone during the crystal growth so as to minimize or eliminate the possibility of rapid over-pressurization of the apparatus upon exposure to the atmosphere.

Abstract: The cooling speed of the portion near the rear part of a single-crystal body and passing through the defect-forming temperature zone is kept the same as that of the front portion of the single-crystal body. Namely, the heater is kept in operation while pulling the single crystal silicon subsequent to forming the tail of the single crystal silicon and the cooling speed throughout the whole single-crystal body in the defect-forming temperature zone is kept below 15.degree. C./min (levels A and B). Furthermore, the length of the tail is preset in the process of pulling the single crystal silicon so that the single-crystal body cools down slowly while passing through the defect-forming temperature zone (level C).

Abstract: A single crystal is grown in accordance with a Czochralski method such that the time for passing through a temperature zone of 1150-1080.degree. C. is 20 minutes or less, or such that the length of a portion of the single crystal corresponding to the temperature zone of 1150-1080.degree. C. in the temperature distribution is 2.0 cm or less. Alternatively, the single crystal is grown such that the time for passing through a temperature zone of 1250-1200.degree. C. is 20 minutes or less, or such that the length of a portion of the single crystal corresponding to the temperature zone of 1250-1200.degree. C. in the temperature distribution is 2.0 cm or less. This method decreases both the density and size of so-called grown-in defects such as FPD (100 defects/cm.sup.2 or less), LSTD, and COP (10 defects/cm.sup.2 or less) to thereby enable efficient production of a single crystal having an excellent good chip yield (80% or greater) in terms of oxide dielectric breakdown voltage characteristics.

Abstract: When the silicon single crystal is pulled up, the nucleation rate of the void cluster is obtained from the forming energy of the cluster of the vacancies in the silicon single crystal. The growth shrinkage of the cluster is obtained basing on the deviation of the flowing-into amount to the cluster of the vacancies and the self-interstitials, and the pulling-up speed or the temperature distribution of the furnace is modified to inhibit the growth of the cluster so as to inhibit the grown-in defects of the silicon single crystal.

Abstract: A process for producing silicon wafers with low defect density is one wherein a) a silicon single crystal having an oxygen doping concentration of at least 4*10.sup.17 /cm.sup.3 is produced by molten material being solidified to form a single crystal and is then cooled, and the holding time of the single crystal during cooling in the temperature range of from 850.degree. C. to 1100.degree. C. is less than 80 minutes; b) the single crystal is processed to form silicon wafers; and c) the silicon wafers are annealed at a temperature of at least 1000.degree. C. for at least one hour. Also, it is possible to prepare a silicon single crystal based upon having an oxygen doping concentration of at least 4*10.sup.17 /cm.sup.3 and a nitrogen doping concentration of at least 1*10.sup.14 /cm.sup.3 for (a) above.