Abstract: A method is provided for producing a silica container arranged with a substrate, having a rotational symmetry, comprised of mainly a silica, and containing gaseous bubbles at least in its peripheral part, and an inner layer, formed on an inner surface of the substrate and comprised of a transparent silica glass; wherein a powdered silica, having particle diameter of 10 to 1000 ?m, containing Ca, Sr, and Ba with the total concentration of 50 to 5000 ppm by weight, and releasing hydrogen molecules with the amount of 3×1016 to 3×1019 molecules/g upon heating at 1000° C. under vacuum, is prepared at least as a powdered raw material for forming the inner layer, and then the inner layer is formed from the powdered silica as the powdered raw material for forming the inner layer.

Abstract: A quartz glass crucible which has a non-transparent outer layer formed through melting a natural silica powder and a transparent layer formed in the inside of the outer layer, wherein the transparent layer comprises a natural quartz layer having a thickness of 0.4 to 5.0 mm transparent layer comprising a synthetic quarts glass is formed thereon in the inside of the crucible in the range of 0.15 to 0.55 L relative to L, which is the distance from the center of the bottom of the inner surface of the quartz glass crucible to the upper end thereof along the inner surface thereof. The quartz glass crucible can be suitably used for suppressing the occurrence of vibration and reducing the generation of roughened face in the surface of a crucible, and thus for pulling up a silicon single crystal with enhanced stability.

Abstract: The invention provides a method for producing a quartz glass jig for use in semiconductor industries, which enables increasing the surface layer cleanliness simply and surely at low cost; it also provides a quartz glass jig improved in surface layer cleanliness. The inventive means for resolution are a method comprising processing a quartz glass raw material into a desired shape by a treatment inclusive of fire working, annealing for stress removal, and cleaning treatment to obtain the final product, the method is characterized by that it comprises performing gas phase etching step and gas phase purification step on the surface layer of the quartz glass jig after applying the annealing treatment for stress removal but before the cleaning treatment, wherein the gas phase purification step is carried out continuously after the gas phase etching step.