Abstract: Leakage of silicon melt is monitored and touch of a seed crystal at the silicon melt is detected, and in addition, reinforcement of a vitreous silica crucible to be endurable during pulling for a long time and decrease of impurity concentration of a silicon single crystal can be expected. A method for manufacturing a silicon single crystal is provided.

Abstract: The present invention provides a method of manufacturing a vitreous silica crucible including: a silica powder supplying process of supplying a material silica powder into a mold for molding a vitreous silica crucible, to form a silica powder layer, and an arc fusing process of arc fusing the silica powder layer by arc discharge generated by carbon electrodes, wherein the arc fusing process includes processes of measuring temperatures at measuring points provided on different heights of an inner surface of the silica powder layer while rotating the mold, and controlling the arc discharge to enable detection, at each measuring point, of a local maximum point which appears first in the arc fusing process.

Abstract: There is provided a method of manufacturing a vitreous silica crucible having non-bubbles on the inner surface without necessitating new apparatuses for grinding and polishing and without damaging the productivity. According to the present invention, there is provided a method of manufacturing a vitreous silica crucible including the processes of: gathering a vitreous silica layer containing residual bubbles existing in a near-surface region of the transparent layer of the vitreous silica crucible by controlling the number of rotations applied to the vitreous silica crucible in a state that an inner surface side of the vitreous silica crucible is fused by arc heating; and moving a portion of a non-bubble layer in the surface of the transparent layer exposed by movement of the residual bubble-containing layer to cover a region in which bubbles have gathered with the non-bubble layer.

Abstract: A method of manufacturing a fused silica crucible by heating and melting a vitreous silica powder compact shaped into a mold using arc discharge of electrodes arranged around a rotation shaft of the mold, includes the steps of: arranging the electrodes in a ring shape, and setting a ratio W/R of a horizontal distance W between the electrode front end and the surface of the vitreous silica powder compact to a vitreous silica powder compact opening radius R, for at least a predetermined time during arc heating, to be in the range of 0.002 to 0.98.

Abstract: An object of the present invention is to provide a crucible handling device that can firmly sandwich and reliably move a quartz glass crucible under a clean environment and a method of handling a quartz glass crucible using the crucible handling device.

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: 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: To provide a treatment method having excellent purification effect, in which impurities having high ionicity in a silica powder can be removed in a short time, an apparatus thereof, and a purified silica powder. A purification method of a silica powder comprises making a silica powder into a fluid state; contacting a purified gas to the silica powder in the fluid state at high temperature; and thereby removing impurity components of the silica powder. In the method, the silica powder in the fluid state is positioned in a magnetic field region. Further, the silica powder is contacted with the purified gas, while applying voltage to the silica powder by an electric field generated by moving of the silica powder. Preferably, the silica powder in a fluid state is positioned in the magnetic region of 10 gausses or more, and contacted with the purification gas at a temperature of I000° C. or more.

Abstract: A silica glass crucible having a sidewall portion and a bottom portion is provided with a first synthetic silica glass layer constituting an inner layer at least in the sidewall portion, a second synthetic silica glass layer constituting an inner layer at least in a region including a center of the bottom portion, and a natural silica glass layer constituting an outer layer in the sidewall portion and the bottom portion. A melting rate of the second synthetic silica glass layer with respect to a silicon melt is higher than that of the first synthetic silica glass layer. An aluminum concentration of the second synthetic silica glass layer is higher than that of the first synthetic silica glass layer.

Abstract: A carbon electrode grinding apparatus for shaping a front end of an arc discharge carbon electrode is provided with front end grinding blades configured to grind a front end surface of the carbon electrode, lateral surface grinding blades configured to grind a surface from the front end surface to a base end of the carbon electrode, and rotation means configured to rotate and drive the front end grinding blades and the lateral surface grinding blades around a rotation axis line coincident with an axis line of the carbon electrode.

Abstract: An arc discharge method includes the steps of heating and melting a non-conductive object by arc discharge using a plurality of carbon electrodes in a output range of 300 to 12,000 kVA; and setting a ratio of the distance between a contact position at which the carbon electrodes come in contact with each other and a front end to the diameter of the carbon electrode during the start of the arc discharge to be in the range of 0.001 and 0.9.

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 closure for silica glass crucible to be mounted on an opening portion of a silica glass crucible is provided with a peripheral edge mounting portion closely adhered to an inner peripheral end of the opening portion.

Abstract: Provided is an apparatus for manufacturing a vitreous silica crucible, which is capable of stably manufacturing a high quality vitreous silica crucible by stabilizing heat generation through an arc discharge. The apparatus for manufacturing a vitreous silica crucible includes a mold that defines a shape of a vitreous silica crucible, carbon electrodes that generate an arc discharge for fusing a silica powder molded body formed in the mold, and a power supply device that supplies power to the carbon electrodes. The power supply device includes a saturable reactor that is provided on a supply path of the power to the carbon electrodes and has variable reactance, and a control device that controls the power supplied to the carbon electrodes by changing the reactance of the saturable reactor.

Abstract: Provided is a vitreous silica crucible for pulling a silicon single crystal, which stably suppresses surface vibration of a silicon melted solution filled therein and has a long life, and a method for manufacturing the same. The vitreous silica crucible for pulling a silicon single crystal includes a peripheral wall portion, a curved portion, and a bottom portion, wherein a plurality of minute concave portions are formed on a certain area of an inner surface of the peripheral wall portion, and a plurality of bubbles are formed on a lower position of the minute concave portions.

Abstract: Provided is an apparatus for manufacturing a vitreous silica crucible, which is capable of stably manufacturing a high quality vitreous silica crucible by stabilizing heat generation through an arc discharge. The apparatus for manufacturing a vitreous silica crucible includes a mold that defines a shape of a vitreous silica crucible, carbon electrodes that generate an arc discharge for fusing a silica powder molded body formed in the mold, and a power supply device that supplies power to the carbon electrodes. The power supply device includes a saturable reactor that is provided on a supply path of the power to the carbon electrodes and has variable reactance, and a control device that controls the power supplied to the carbon electrodes by changing the reactance of the saturable reactor.

Abstract: During fabrication of a vitreous silica crucible, contamination of the vitreous silica crucible due to wear particles and debris of components of an apparatus for manufacturing a vitreous silica crucible is reduced by preventing damage and wear of the components of the apparatus due to silica fume. The apparatus for manufacturing a vitreous silica crucible is divided into a lower section for accommodating a mold and a mold driving system and an upper section for accommodating an arc electrode driving system, wherein a sectioning member including one or more communication paths for allowing penetration of arc electrodes, thereby the air flow is controlled so as to reduce exchange between gas in the upper section and gas in the lower section.

Abstract: By providing a method capable of avoiding invasion of starting material powder for crucible into an inner face of the crucible, it is made possible to reliably avoid the invasion of foreign substances into a vitreous silica crucible until an actual use time of the crucible and to handle the crucible with no contamination. A cover 3 mounted onto an opening portion 2 of a vitreous silica crucible 1, comprising a flange portion 4 in close contact with an outer peripheral end 2a of the opening portion 2, is mounted onto the crucible 1.

Abstract: Provided is a vitreous silica crucible which has a special region for suppressing vibration of melt surface during pulling of a silicon single crystal and at the same time, a marking capable of accurately monitoring a changed position of the melt surface when passing through the special region. The special region for preventing sloshing of silicon melt is provided on an inner wall of a straight body portion, and the marking is provided at least at an upper end and a lower end of the special region.

Abstract: A method of producing a quartz glass crucible by arc melting a quartz powder molded product loaded on the inner side of a mold while performing vacuum suction, includes initiating the melting of quartz powder from the rim edge of a quartz powder molded product, subsequently lowering the arc electrode or raising the mold to heat and melt the sections on the downside of the rim edge. The method is preferably carried out such that the inner surface of the crucible is sealed within a time corresponding to 10% of the total arc time starting from the initiation of arc melting, and the seal thickness is 3 mm or less. The quartz glass crucible thus produced is useful for the pulling up of silicon single crystals and has a uniform glass layer with fewer internal bubbles.