Abstract: A method for manufacturing a silicon single crystal is provided including producing a silicon melt in a chamber by melting a silicon raw material loaded into a silica glass crucible under a reduced pressure and high temperature, removing gas bubbles from within the silicon melt by rapidly changing at least the pressure or temperature within the chamber, and pulling up the silicon single crystal from the silicon melt after the gas bubbles are removed. When the pressure is rapidly changed, the pressure within the chamber is rapidly changed at a predetermined change ratio. In addition, when the temperature is rapidly changed, the temperature within the chamber is rapidly changed at a predetermined change ratio. In this way, Ar gas attached to an inner surface of the crucible and h is the cause of the generation of SiO gas is removed.

Abstract: A method for manufacturing a quartz glass crucible has a deposition step of depositing quartz powder on an inner wall surface of a bottomed cylindrical mold, while rotating the mold, and a melting step of obtaining the quartz glass crucible by vitrifying the quartz powder deposited on the inner wall surface of the mold by heating and melting the quartz powder. In the deposition step, under a state where the quantity of electrostatic charge of the quartz powder is controlled to be within a range of 1.0 kV or below in absolute value, the quartz powder is applied to the inner wall surface of the mold, and the thickness of the quartz glass crucible is controlled by maintaining the density of the quartz powder deposition layer on the inner wall surface of the mold within a fixed range.

Abstract: A fluid-cooled mold for the production of a quartz crucible provided in its interior with a space for flowing of cooling fluid comprises an outer mold section made from a heat-conductive metal or alloy material and an inner mold section closely arranged to an inner surface of the outer mold section and made from a heat-resistant material.

Abstract: In a silica glass crucible used for pulling a silicon crystal, a circumferential maximum tolerance of each of bubble content, wall thickness and transmission as measured over a full circumference of the crucible at a same height position is not more than 6%.

Abstract: A silica glass crucible used for pulling up a silicon single crystal and made from natural silica a raw material is provided with a region within a certain range from the center of a bottom section of the crucible and up to 0.5 mm deep from an inner surface and which substantially does not include gas bubbles, wherein an average value of a concentration of Al included in a region within the certain range from the center of the bottom section of the crucible and up to 0.5 mm deep from the inner surface is 30 ppm or more and 150 ppm or less. In the case where the inner layer of the crucible bottom section is formed in this way, dents in the inner surface are prevented and the generation of gas bubbles is reduced.

Abstract: To provide a silica glass crucible, wherein there are no problems of generating a sinking and buckling when said crucible is used for pulling up silicon single crystal at a high temperature. The silica glass crucible used for pulling up the silicon single crystal, wherein at least an outer surface of a wall part of the crucible is covered with fine grooves having a length of less than 200 ?m, a width of less than 30 ?m and a depth of from more than 3 ?m to less than 30 ?m. Preferably, said fine groves are formed by carrying out a sand-blast treatment and a hydrofluoric acid etching and exist on more than 10% of the outer surface of the crucible, and a sliding frictional coefficient of the outer surface of the crucible to a carbon at 1500 degree C. is more than 0.6.

Abstract: A surface modified quartz glass crucible and a process for modifying the crucible includes a layer of a metal oxide on the whole or a part of the inside and/or outside of the crucible, and baking it. At least an inside surface of the crucible is coated with a said metal oxide of magnesium, calcium, strontium or barium. The coated layer of the crucible does not abrade easily and provides a high dislocation free ratio of silicon single crystals pulled by using the crucible.

Abstract: A silica glass crucible for pulling up a silicon single crystal including an outer layer formed from a natural silica glass layer, and an inner layer formed from a synthetic silica glass layer, wherein the synthetic silica glass layer includes a first synthetic silica glass layer formed in a region within a certain range from the center of a crucible bottom section, and a second synthetic silica glass layer formed in a region which excludes the formation region of the first synthetic silica glass layer, and wherein the first synthetic silica glass layer has a thickness of 0.5 mm or more and 1.5 mm or less and a concentration of an OH group included in the first synthetic silica glass layer being 100 ppm or less.

Abstract: A modified synthetic silica powder is produced by heating in vacuum an amorphous synthetic silica powder produced by a sol-gel process, and then cooling the heated silica powder in an atmosphere containing helium. When the modified synthetic silica powder is fused and vitrified in a process of crucible production, the resulting quartz glass crucible contains hardly any bubbles.

Abstract: A silica glass crucible for pulling up a silicon single crystal including a wall part, a corner part and a bottom part is provided with an outer layer formed from an opaque silica glass layer which includes many bubbles, and an inner layer formed from a transparent silica glass layer which substantially does not include bubbles, wherein at least one part of an inner surface of the wall part and the corner part being an uneven surface formed with multiple damaged parts having a depth of 50 ?m or more and 450 ?m or less, and wherein a region among the inner surface of the bottom part within a certain range from the center of the bottom part being a smooth surface which does is substantially not formed with damage.

Abstract: A silica glass crucible used for pulling single-crystal silicon, which includes a cylindrical straight body part, a bottom part and a curved part located between the straight body part and the bottom part, wherein the curvature radius of the inner wall surface of the curved part is 100 to 240 mm. Variation of the wall thickness W of the curved part is preferably 0.1 to 1.4 mm/cm.

Abstract: Disclosed is a silica glass crucible employed in pulling silicon single crystals. The crucible comprises at least a transparent layer, semitransparent layer, and opaque layer disposed from the inner surface side to the outer surface side of the crucible. The content of bubbles in the transparent layer is less than 0.3 percent; the content of bubbles in the semitransparent layer falls within a range of from 0.3 to 0.6 percent; and the content of bubbles in the opaque layer is greater than 0.6 percent.

Abstract: A mold for the production of a silica crucible by heat-fusing silica or quartz powder attached onto an inner wall of a rotating mold, wherein a ring-shaped heat insulating barrier material having a specified inner diameter is disposed on an inner peripheral wall of an upper opening portion of the mold corresponding to an upper region of the silica crucible.

Abstract: The disclosed is a method of manufacturing a silica glass crucible for pulling silicon single crystals. In the method, reduced pressure is imparted from the inner surface to the outer surface of a crucible-shaped molded product and the crucible-shaped molded product is arc-fused while rotating the same to form a silica glass crucible with a transparent layer on the inner surface side and a bubble layer on the outer surface side. The inner surface of the wall portion of the silica glass crucible is fused a second time by arc fusion to cause bubbles present in the transparent layer of the inner surface of the wall portion to be displaced toward the bottom portion of the inner surface of the wall portion. The inner surface of the bottom portion of the silica glass crucible is fuse a second time by arc fusion to cause bubbles present in the transparent layer of the inner surface of the bottom portion to be displaced toward the periphery of the inner surface of the bottom portion.

Abstract: A silica glass crucible for pulling up a silicon single crystal including a wall part and a bottom part is provided with a natural silica glass layer which forms at least one part of a an inner surface of the bottom part, and a synthetic silica glass layer which forms at least an inner surface of the wall part, wherein a concentration of Ca included in the natural silica glass layer is 0.5 ppm or less.

Abstract: The arc discharge apparatus comprises a plurality of carbon electrodes connected to respective phases of a power supply for heating a silica powder and causing it to fuse by generating arc discharge between the carbon electrodes. All of the carbon electrodes have a density in a range from 1.30 g/cm3 to 1.80 g/cm3, and variability in density among the carbon electrodes is 0.2 g/cm3 or less. The carbon particles that constitute the carbon electrodes preferably have a particle diameter of 0.3 mm or less.

Abstract: An arc melting high-purity carbon electrode is capable of forming stable arc at the time of arc discharge, and it is possible to produce a vitreous silica crucible with good properties, which does not cause local lack of the electrode and does not create black foreign materials or concave portions on the inner surface of the crucible. The arc melting high-purity carbon electrode is a carbon electrode used to heat and melt silica powder by arc discharge, in which the density of the carbon electrode is equal to or more than 1.60 g/cm3 and equal to or less than 1.80 g/cm3, and is formed of high-purity carbon particles having a diameter of 0.05 mm or less.

Abstract: A silica glass crucible used for pulling single-crystal silicon, which includes a cylindrical straight body part, a bottom part and a curved part located between the straight body part and the bottom part, wherein the curvature radius of the inner wall surface of the curved part is 100 to 240 mm. Variation of the wall thickness W of the curved part is preferably 0.1 to 1.4 mm/cm.

Abstract: To provide a silica glass crucible, wherein there are no problems of generating a sinking and buckling when said crucible is used for pulling up silicon single crystal at a high temperature. The silica glass crucible used for pulling up the silicon single crystal, wherein at least an outer surface of a wall part of the crucible is covered with fine grooves having a length of less than 200 ?m, a width of less than 30 ?m and a depth of from more than 3 ?m to less than 30 ?m. Preferably, said fine groves are formed by carrying out a sand-blast treatment and a hydrofluoric acid etching and exist on more than 10% of the outer surface of the crucible, and a sliding frictional coefficient of the outer surface of the crucible to a carbon at 1500 degree C. is more than 0.6.

Abstract: A method of manufacturing a carbon electrode for melting an object to be melted by arc discharge, includes: a rubbing step of rubbing the surface of the carbon electrode before power is supplied with a rubbing material of the same type as the object to be melted.