Abstract: In the manufacture of a silicon single crystal by the Czochralski method, there is provided a seed crystal for use in the production of the silicon single crystal. This seed crystal is capable of preventing creation of a dislocation occurring during the immersion of the seed crystal in the molten silicon and withstanding the load of a silicon single crystal of great weight as well. There is also a method for the production of the seed crystal and a method for the production of a silicon single crystal which enables the ratio of elimination of dislocation to be increased.

Abstract: A method and apparatus for controlling the diameter of a monocrystalline ingot as it is being pulled from a melt by changing the temperature of the melt. The ingot is pulled from the melt at a target rate that substantially follows a predetermined velocity profile. A temperature model represents variations in the melt temperature in response to variations in power supplied to a heater for heating the melt. In generating a temperature set point representing a target melt temperature, an error between a target diameter and a measured diameter of the ingot is determined and proportional-integral-derivative (PID) control is performed on the error signal. The PID control generates the temperature set point as a function of the error signal. In turn, the temperature model determines a power set point for the power supplied to the heater as a function of the temperature set point generated by the PID control and the power supplied to the heater is adjusted according to the power set point.

Abstract: The optical fluoride crystal treatment device of the invention includes a enclosure (12) separating the device from its external environment, heating means to heat and keep the internal volume (16) of said enclosure (12) at a predetermined temperature, at least one hollow platform (20) delimiting an internal chamber (22) whose upper wall (24) bears at least two independent diffusers (30) each delimiting a cavity (32) able to receive a unitary quantity (100) of said optical fluoride crystal substance, each of said cavities (32) communicating with said internal chamber (22) of the corresponding platform (20), a gas supply source containing said reactive gas, and means (50, 52, 54) for distributing said gas containing said reactive gas from said supply source to the inside of the internal chamber of each platform and having means (44) for regulating the pressure of said distributed gas.

Abstract: A method for preparing a high-quality garnet single crystal represented by the composition formula CaxNbyGazO12 (2.9<x<3.1, 1.6<y<1.8, 3.1<z<3.3) is provided. The single crystal can preferably be used as a single crystal substrate for forming a defect-free single crystal of bismuth-substituted rare-earth iron garnet thereon by liquid-phase epitaxial deposition. The method is to prepare a single crystal by the Czochralski technique, the single crystal having a garnet structure being represented by the composition formula CaxNbyGazO12 (2.9<x<3.1, 1.6<y<1.8, 3.1<z<3.3). The crystal is grown at a crystal growth rate g less than or equal to 1.72 mm/h. The crystal is preferably grown in an atmosphere containing oxygen 0.4% or more by volume and below 10.0% by volume.

Abstract: In one aspect of the invention, a method for pressurized annealing of lithium niobate or lithium tantalate structures, such as optical modulators and optical wave guides, comprises pressurizing an oxygen atmosphere containing a lithium niobate or lithium tantalate structure above normal atmospheric pressure, heating the structure to a temperature ranging from about 150 degrees Celsius to about 1000 degrees Celsius, maintaining pressure and temperature to effect ion exchange or to relieve stress, and cooling the structure to an ambient temperature at an appropriate ramp down rate.

Abstract: In the CZ process using a cooling member surrounding a single crystal, the cooling member is permitted to effectively serve to increase a pulling speed. Cracks of the single crystal due to excessive cooling are prevented to occur. A high crystal quality is acquired. In order to realize these objects, the temperature of the inner peripheral surface of the cooling member 6 opposing to the outer peripheral surface of the single crystal 4 is restricted to 500° C. or below, even in the lower end, the temperature of which becomes the highest. To achieve this restriction, the thickness T of the cooling member 5 is 10 to 50 mm. The height H of the cooling member 6 is 0.1 to 1.5 times the diameter D of the single crystal 4.

Abstract: A method and apparatus for growing a crystalline or poly-crystalline body from a melt is described, wherein the melt is retained by capillary attachment to edge features of a mesa crucible. The boundary profile of the resulting melt surface results in an effect which induces a ribbon grown from the surface of the melt to grow as a flat body. Further, the size of the melt pool is substantially reduced by bringing these edges close to the ribbon, thereby reducing the materials cost and electric power cost associated with the process.

Abstract: The present invention provides an apparatus and a method for producing a silicon semiconductor single crystal which can stabilize and homogenize an amount of precipitated oxygen in the direction of the crystal growth axis when growing a silicon semiconductor single crystal. The apparatus for producing a silicon semiconductor single crystal by the Czochralski method comprises a main growth furnace having a crucible retaining silicon melt disposed therein for growing a silicon semiconductor single crystal, and an upper growth furnace for housing therein and cooling the silicon semiconductor single crystal pulled from the silicon melt, wherein the upper growth furnace communicated to a ceiling section of the main growth furnace is provided with an upper insulating member for surrounding a pulled silicon semiconductor single crystal.

Abstract: A method for growing a silicon single crystal ingot by a Czochralski method, which is capable of providing silicon wafers having very uniform in-plane quality and which results in improvement of semiconductor device yield. A method is provided for producing a silicon single crystal ingot by a Czochralski method, wherein when convection of a silicon melt is divided into a core cell and an outer cell, the silicon single crystal ingot is grown under the condition that the maximal horizontal direction width of the core cell is 30 to 60% of a surface radius of the silicon melt. In one embodiment the silicon single crystal ingot is grown under the condition that the maximal vertical direction depth of the core cell is equal to or more than 50% of the maximal depth of the silicon melt.

Abstract: A method capable of securely pulling up a heavy single crystal is described.

Abstract: By using an InP single crystal substrate of the present invention in which the oxygen atom concentration is within the range of 1×1017 to 1×1018 atoms/cm3 for vapor phase epitaxial growth such as the MOCVD method, the occurrence of protrusions referred to as hillocks on the surface of the epitaxial layer formed on the substrate can be reduced, thereby allowing the providing of an InP single crystal substrate able to accommodate reduced thickness, multi-layering and enhanced function of the epitaxial layer.

Abstract: A crystal puller for growing monocrystalline ingots includes a side heater adjacent a crucible for heating the crucible and a melt heat exchanger sized and shaped for surrounding the ingot and disposed adjacent a surface of the melt. The heat exchanger includes a heat source having an area for radiating heat to the melt for controlling heat transfer at the upper surface of the melt. The melt heat exchanger is adapted to reduce heat loss at the exposed upper surface portion. Methods for growing single crystal silicon crystals having desired defect characteristics are disclosed.

Abstract: Additional charge of a solid raw material 13 in the shapes of granules/lumps, low in raw material cost, and with no risk of cracking, is performed into a molten raw material 14 in a crucible in a static manner without solidifying a surface of the molten raw material 14 in the crucible 3. A bottom of a cylindrical raw material vessel 10 made of a material non-meltable when being in contact with the molten raw material 14 in the crucible 3 is closed with a bottom cover 11 made of a material meltable and removable when being in contact with the molten raw material 14 in the crucible 3. The raw material vessel 10 in a state of being filled with the solid raw material 13 in the shapes of granules/lumps is hung down above the crucible 3 to immerse the lower portion thereof into the molten raw material 14 in the crucible 3.

Abstract: A process for controlling the amount of insoluble gas trapped by a silicon melt is disclosed. Polycrystalline silicon is charged to a crucible in a crystal pulling apparatus and the apparatus sealed and evacuated. After evacuation, the crystal pulling apparatus is backfilled at least once with a gas having a high solubility in silicon, such as nitrogen. The highly soluble gas fills in cavities between the polycrystalline silicon pieces and between the pieces and the crucible such that when the silicon is melted and bubbles form in the molten silicon the bubbles will solubilize into the melt instead of becoming entrapped in the growing crystal.

Abstract: The single crystal of alkaline earth metal fluoride of the invention is produced by a single crystal pulling method, has a straight barrel part diameter of not less than 17 cm, preferably has a straight barrel part length of not less than 5 cm, and has a light transmittance, as measured at a wavelength of 632.8 nm, of not less than 80%, preferably 90 to 98%. Further, the main crystal growth plane of the single crystal of the invention is the {111}plane or the {100}plane. The single crystal of alkaline earth metal fluoride of the invention has a large diameter as described above, and in spite that it is in an as-grown state, the peripheral surface is not opaque and the visible light transmittance is high. Therefore, evaluation of bubbles or inclusions in the crystal becomes feasible without performing complicated machining of the crystal, and from the single crystal, a large-sized optical material having advantageous properties such as high quality and high uniformity can be cut out.

Abstract: A thermal annealing process for producing a low defect density single crystal silicon wafer. The process includes thermally annealing a wafer having a first axially symmetric region which extends radially inwardly from the circumferential edge, contains silicon self-interstitials as the predominant intrinsic point defect and is substantially free of agglomerated interstitial defects and a second axially symmetric region which has vacancies as the predominant intrinsic point defect. The wafer is subjected to a thermal anneal at a temperature in excess of about 1000° C. in an atmosphere of hydrogen, argon or a mixture thereof to dissolve agglomerated vacancy defects present in the second axially symmetric region within a layer extending from the front side toward the central plane.

Abstract: The object of the present invention is to provide an as-grown single crystal of calcium fluoride having a large diameter and small birefringence. The as-grown single crystal of calcium fluoride according to the present invention is obtained by a single crystal pulling method (Czochralski method), has a straight barrel part diameter of 17 cm or more, preferably has a straight barrel part length of 50 mm or more, and has a birefringence of not more than 3 nm/cm, preferably 0.1 to 2.0 nm/cm.

Abstract: The process for growing single crystals, wherein crystal material is melted in a crucible and a crystal nucleus is immersed in the molten crystal material and slowly pulled out, wherein the crystal formed during the pulling is kept at a temperature close to melting temperature of the output material. The invention also includes a device for practicing the above process.

Abstract: A single crystal pulling apparatus for a metal fluoride comprising a crucible provided in a chamber and filling a molten solution of a single crystal manufacturing material, a melting heater provided to surround the crucible, a vertically movable single crystal pulling bar including a seed crystal on a tip and coming in contact with the molten solution of the single crystal manufacturing material filled in the crucible, a heat insulating wall provided in the chamber to surround at least a peripheral side portion of a single crystal pulling region in an upper part of the crucible, a ceiling board for closing an opening portion of an upper end in an upper part of the heat insulating wall, and a single crystal pulling chamber surrounded by the heat insulating wall and the ceiling board, wherein the ceiling board is provided with at least an inserting hole for inserting the single crystal pulling bar, and a coefficient of thermal conductivity in a direction of a thickness of the ceiling board is 1000 to 50000 W/m

Abstract: An inexpensive method of coating silicon shot with boron atoms comprises (1) immersing silicon shot in a boron dopant spin-on solution comprising a borosilicate, a polymer precursor, and a volatile solvent, and (2) removing the solvent so as to leave a polymeric coating containing borosilicate on the shot. A precise amount of this coated shot may then be mixed with a measured quantity of silicon pellets and the resulting mixture may then be melted to provide a boron-doped silicon melt for use in growing p-type silicon bodies that can be converted to substrates for photovoltaic solar cells.

Abstract: A method of making a fracture-resistant large-size calcium fluoride single crystal is described, which is suitable for an optical component for radiation in the far UV range. The calcium fluoride raw material for the single crystal is first melted and subsequently solidified by cooling the melt to form a single crystal. However the calcium fluoride raw material is doped with from 1 to 250, preferably 1 to 100, ppm of strontium, preferably added as strontium fluoride, and contains from 1 to 10 ppm of sodium as well as up to 100 ppm of other impurities.

Abstract: A single crystal ceramic material for optical and optoelectronic applications is d, including a single crystal spinel having a general formula aAD·bE2D3, wherein A is selected from the group consisting of Mg, Ca, Zn, Mn, Ba, Sr, Cd, Fe, and combinations thereof, E is selected from the group consisting Al, In, Cr, Sc, Lu, Fe, and combinations thereof, and D is selected from the group consisting O, S, Se, and combinations thereof.

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.

Abstract: In a Czochralski (CZ) single crystal puller equipped with a cooler and a thermal insulation member, which are to be disposed in a CZ furnace, smooth recharge and additional charge of material are made possible. Further, elimination of dislocations from a silicon seed crystal by use of the Dash's neck method can be performed smoothly. To these ends, there is provided a CZ single crystal puller, wherein a cooler and a thermal insulation member are immediately moved upward away from a melt surface during recharge or additional charge of material or during elimination of dislocations from a silicon seed crystal by use of the Dash's neck method.

Abstract: There are disclosed a silicon seed crystal which is composed of silicon single crystal and used for the Czochralski method, wherein oxygen concentration in the seed crystal is 15 ppma (JEIDA) or less, a silicon seed crystal which is used for the Czochralski method, wherein the silicon seed crystal does not have a straight body, and a method for producing a silicon single crystal by the Czochralski method comprising using said seed crystal, bringing a tip end of the seed crystal into contact with a silicon melt to melt the tip end of the seed crystal, with or without performing necking operation, and growing a silicon single crystal.

Abstract: A control method for use with a crystal puller for growing a monocrystalline semiconductor crystal from a melt according to the Czochralski process. The method includes defining an initial interval of time for observing growth of the crystal being pulled from the melt and determining diameter variations occurring during the interval. Based on the variations in the crystal diameter, the method defines a function r(t). By performing a best fit routine on the function r(t), the method deduces current values of crystal radius rf, meniscus height hf and growth rate Vgf at the end of the observation interval. The method also includes determining pull rate and heater power parameters as a function of the growth rate to control the crystal puller to minimize variations in both crystal diameter and growth rate during subsequent growth of the crystal.

Abstract: The present invention provides aluminum oxide crystalline materials including dopants and oxygen vacancy defects and methods of making such crystalline materials. The crystalline materials of the present invention have particular utility in optical data storage applications.

Abstract: An epitaxial silicon wafer which comprises a silicon wafer produced by a method characterized as comprising pulling up a silicon single crystal under a condition wherein when an oxygen concentration is 7×1017 atoms/cm3 a nitrogen concentration is about 3×1015 atoms/cm3 or less, and when an oxygen concentration is 1.6×1018 atoms/cm3 a nitrogen concentration is about 3×1014 atoms/cm3 or less, and, an epitaxial film formed on the wafer. The epitaxial film, being formed on such a wafer, has crystal defects, which are observed as LPD of 120 nm or more on the epitaxial film, in a range of 20 pieces/200-mm wafer or less. The epitaxial silicon wafer contains nitrogen atoms doped therein and also has satisfactory characteristics as that for use in a semiconductor device.

Abstract: Bulk Aluminum Antimonide (AlSb)-based single crystal materials have been prepared for use as ambient (room) temperature X-ray and Gamma-ray radiation detection.

Abstract: A process for modifying the surface of a quartz glass crucible and a modified quartz glass crucible produced by the process, where the crucible has a transparent coated layer containing a crystallization accelerator on the surface. The process includes coating a mixed solution containing a metal salt and a partial hydrolyzate of alkoxysilane oligomer on the surface of the crucible and heating to obtain a quartz glass crucible having a transparent coated layer. The crystallization promoter contains a metal oxide or a metal carbonate dispersed in a silica matrix.

Abstract: A semi-insulating zinc-oxide (ZnO) single crystal. The crystal has resistivity of at least 1.5×103 ohm-centimeter (&OHgr;-cm). The ZnO crystal can be produced from a melt contained by solid-phase ZnO to prevent introduction of undesired impurities into the crystal. The crystal can be a bulk single crystal that is cut and processed into wafer form of specified thickness. A dopant in a concentration ranging from 1×1015 atoms per cubic centimeter (atoms/cc) to 5×1021 atoms/cc can increase resistivity of the crystal relative to intrinsic ZnO. The dopant can be lithium (Li), sodium (Na), copper (Cu), nitrogen (N), phosphorus (P), and/or manganese (Mn).

Abstract: A method for manufacturing calcium fluoride single crystal includes the step of cooling the calcium fluoride single crystal so that maximum shear stress inside the calcium fluoride single crystal caused by thermal stress is approximately equal to or smaller than critical resolved shear stress (&tgr;c) in a <1 1 0> direction of on a {0 0 1} plane of the calcium fluoride single crystal.

Abstract: An apparatus is provided which is to be used in producing single crystals for silicon wafers useful as semiconductor materials and which can stably produce large-diameter, long-length and high-quality single crystals from which wafers limited in the number of grown-in defects can be taken. This silicon single crystal production apparatus comprises a cooling member surrounding the single crystal to be pulled up and having an internal surface coaxial with the pulling axis and thermal insulating members disposed outside the outer surface and below the bottom surface of the cooling member, the cooling member having an internal surface diameter of 1.20D to 2.50D (D being the diameter of the single crystal to be pulled up) and a length of not less than 0.25D, the distance from the melt surface to the bottom surface of the cooling member being 0.30D to 0.

Abstract: A silicon single crystal wafer for a particle monitor is presented, which wafer has an extremely small amount in the surface density of light point defects and is capable of still maintaining a small surface density even after repeating the SC-1. The wafer is prepared by slicing a silicon single crystal ingot including an area in which crystal originated particles are generated, and the surface density of particles having a size of not less than 0.12 &mgr;m is not more than 15 counts/cm2 after repeating the SC-1. More preferably, a silicon single crystal wafer having a nitrogen concentration of 1×1013-1×1015 atoms/cm3 provides a surface density of not more than 1 counts/cm2 for the particles having a diameter of not less than 0.12 &mgr;m even after repeating the SC-1. Hence, a high quality wafer optimally used for a particle monitor can be obtained and a very small number of defects in the wafer make it possible to produce devices.

Abstract: A method for growing solid state laser crystal boules is disclosed that when made into laser rods do not need separate end caps attached to the laser rods. The crystal boule is grown as a single integral unit with three segments. Two segments, the end segments, are un-doped or non-laser active, and they flank a central segment of the boule that is doped with an active laser ion. A first end segment of the crystal boule is first grown from un-doped melt material in a first crucible by slowly withdrawing its growing end from the first melt. The boule is then transferred to a doped melt in a second crucible where its growing end is submersed therein to grow the doped, laser active central segment. The temperature of the melt in the second crucible is initially higher than the growing temperature of the first melt and causes the growing end of the boule to melt.

Abstract: The present invention relates to single crystal silicon, ingot or wafer form, which contains an axially symmetric region in which vacancies are the predominant intrinsic point defect, is substantially free of oxidation induced stacking faults and is nitrogen doped to stabilize oxygen precipitation nuclei therein, and a process for the preparation thereof.

Abstract: A silicon wafer is provided having controlled distribution of defects, in which denuded zones having a sufficient depth inward from the surface of the wafer are combined with a high gettering effect in a bulk region of the wafer. In the silicon wafer, oxygen precipitates, which act as intrinsic gettering sites, show vertical distribution. The oxygen precipitate concentration profile from the top to the bottom surfaces of the wafer includes first and second peaks at first and second predetermined depths from the top and bottom surfaces of the wafer, denuded zones between the top and bottom surfaces of the wafer and each of the first and second peaks, and a concave region between the first and second peaks, which corresponds to a bulk region of the wafer. For such an oxygen precipitate concentration profile, the wafer is exposed to a rapid thermal annealing process in a gas mixture atmosphere comprising ammonia (NH3) and argon (Ar) at temperatures below about 1200° C.

Abstract: The present invention provides a method for producing a silicon wafer, which comprises growing a silicon single crystal ingot having a resistivity of 100 &OHgr;·cm or more and an initial interstitial oxygen concentration of 10 to 25 ppma and doped with nitrogen by the Czochralski method, processing the silicon single crystal ingot into a wafer, and subjecting the wafer to a heat treatment so that a residual interstitial oxygen concentration in the wafer should become 8 ppma or less, and a method for producing a silicon wafer, which comprises growing a silicon single crystal ingot having a resistivity of 100 &OHgr;·cm or more and an initial interstitial oxygen concentration of 8 ppma or less and doped with nitrogen by the Czochralski method, processing the silicon single crystal ingot into a wafer, and subjecting the wafer to a heat treatment to form an oxide precipitate layer in a bulk portion of the wafer, as well as silicon wafers produced by these production methods.

Abstract: An improved method of obtaining a wafer exhibiting high resistivity and high gettering effect while preventing the reduction of resistivity due to the generation of oxygen donors provided by: a) using the CZ method to grow a silicon single crystal ingot having a resistivity of 100 &OHgr;·cm or more, preferably 1000 &OHgr;·cm, and an initial interstitial oxygen concentration of 10 to 40 ppma while doping the crystal with an electrically inactive material such as nitrogen, carbon, or tin, b) processing the ingot into a wafer, and c) subjecting the wafer to an oxygen precipitation heat treatment whereby the residual interstitial oxygen content in the wafer is reduced to about 8 ppma or less.

Abstract: A method of obtaining a wafer exhibiting high resistivity and high gettering effect while preventing the reduction of resistivity due to the generation of oxygen donors, and while further minimizing in-grown defects is provided by: a) using the CZ method to grow a silicon single crystal ingot having a resistivity of 100 &OHgr;·cm or more, preferably 1000 &OHgr;·cm, and an initial interstitial oxygen concentration of 10 to 40 ppma with a v/G ratio of from about 1×10−5 cm2/s·K to about 5×10−5 cm2/s·K, b) processing the ingot into a wafer, and c) subjecting the wafer to an oxygen precipitation heat treatment whereby the residual interstitial oxygen content in the wafer is reduced to about 8 ppma or less.

Abstract: A method for growing solid state laser crystal boules is disclosed that when made into laser rods do not need separate end caps attached to the laser rods. The crystal boule is grown as a single integral unit with three segments. Two segments, the end segments, are un-doped or non-laser active, and they flank a central segment of the boule that is doped with an active laser ion. A first end segment of the crystal boule is first grown from un-doped melt material in a first crucible by slowly withdrawing its growing end from the first melt. The boule is then transferred to a doped melt in a second crucible where its growing end is submersed therein to grow the doped, laser active central segment. The temperature of the melt in the second crucible is initially higher than the growing temperature of the first melt and causes the growing end of the boule to melt.

Abstract: An ingot is manufactured by pulling it up such that V/Ga and V/Gb become 0.23 to 0.50 mm2/minute ° C., respectively, where V (mm/minute) is a pulling-up speed, and Ga (° C./mm) is and axial temperature gradient at the center of the ingot and Gb (° C./mm) is an axial temperature gradient at the edge of the ingot at temperatures in a range of 1,300° C. to a melting pointy of silicon. A wafer obtained by slicing the ingot is heat treated in a reductive atmosphere at temperature in a renge of 1,050° C. to 1,220° C. for 30 to 150 minutes. A silicon wafer free of OSF's, free of COP's, and substantially free of contamination such as Fe and of occurence of slip, is obtained.

Abstract: A crystal puller and method for growing monocrystalline silicon ingots includes first and second electrical resistance heaters in the crystal puller in longitudinal, closely spaced relationship with each other to radiate heat toward the ingot as the ingot is pulled upward within the housing. In one embodiment, the first heater is powered when the ingot is pulled upward to a first axial position above the surface of the molten silicon and the second heater is powered when the ingot is pulled upward to a second axial position above the first axial position. In another embodiment the first and second heaters are powered until the ingot is separated from the molten silicon and then the heating power output of the first and second heaters is reduced to substantially increase the cooling rate at which the ingot is cooled. An adapter mounting the heaters may also be provided for adapting existing crystal pullers to incorporate the heaters.

Abstract: An apparatus and a method that permits a seed crystal to be directed to a precise location of a melt for growing a ribbon-shaped crystal, but after the crystal has commenced growing, the ribbon-shaped crystal is continuously pulled up so as to produce a longitudinally extending crystal using a continuous pulling device. The method for producing a ribbon-shaped crystal includes growing a ribbon-shaped crystal on a seed crystal using a linear pulling device for pulling the seed crystal and a crystal growing at the end of the seed crystal in a vertical direction, and continuing to pull the ribbon-shaped crystal by using a continuous pulling device having a continuous pulling mechanism.

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 is disclosed. The wafer has a front surface, a back surface, and a central plane between the front and back surfaces. 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 heat-treated wafer is then oxidized by heating in the presence of an oxygen-containing atmosphere in order to establish a vacancy concentration profile within the wafer. The oxidized wafer is then cooled from the temperature of said oxidizing heat treatment at a rate which allows some, but not all, of the crystal lattice vacancies to diffuse to the front surface 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: The present invention is directed to a process or method for preparing a metal fluoride pre-melt material of a quality suitable for the preparation and growth of metal fluoride optical monocrystals. The pre-melt material of the invention is prepared using permeable graphite crucibles having a permeability (porosity) greater than 4 cm2/s. Exemplary monocrystals prepared from pre-melts of the invention exhibited improved transmissivity and laser durability relative to monocrystals prepared from convention pre-melt materials. Impurities in the pre-melt arising from the use of scavenger/fluorinating agent in the pre-melt have been shown to be generally less than 10 ppb and be less than 1 ppb.

Abstract: A process for growing a single crystal silicon ingot having an axially symmetric region substantially free 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: A method of growing a crystalline ingot having a <110> orientation, such as a dislocation-free (“DF”) crystalline ingot, is provided. The method of manufacture includes providing a liquidous melt. Next, a seed crystal having a <110> crystal direction is contacted with the surface of the melt. The seed crystal is then withdrawn from the melt to thereby grow a neck. According to one embodiment, the seed elevation rate is automatically modified during the withdrawing step to reduce the diameter of the neck to greater than about 2.5 mm. Thereafter, the seed elevation rate is manually modified to alternate the diameter of the neck between about 2 mm and about 2.5 mm to thereby shape the neck into a recurring hourglass configuration. The neck is then withdrawn from the melt to grow a crystalline ingot having a <110> crystal direction and a diameter of at least about 200 mm.

Abstract: A process for controlling the amount of insoluble gas trapped by a silicon melt is disclosed. After a crucible is charged with polycrystalline silicon, a gas comprising at least about 10% of a gas having a high solubility in silicon is used as the purging gas for a period of time during melting. After the polycrystalline silicon charge has completely melted, the purge gas may be switched to a conventional argon purge. Utilizing a purge gas highly soluble in silicon for a period of time during the melting process reduces the amount of insoluble gases trapped in the charge and, hence, the amount of insoluble gases grown into the crystal that form defects on sliced wafers.

Abstract: A process for preparing a single crystal silicon in accordance with the Czochralski method, is provided. More specifically, by quickly redueing the pull rate at least once during the growth of a neck portion of the single crystal silicon ingot, in order to change the melt/solid interface shape from a concave to a convex shape, the present process enables zero dislocation growth to be achieved in a large diameter neck within a comparably short neck length, such that large diameter ingots of substantial weight can be produced safely and at a high throughput.