Abstract: A silica glass crucible includes a stable, bubble-free inner layer and an opaque outer layer, both layers demonstrating reduced bubble growth during a Czochralski process. When used in the CZ process, little volume change is observed in the crucible wall, and the crucible has little influence on melt level. The present crucible is especially suited for slow silicon ingot pulling with reduced crystalline defects. The fusion process of the present invention controls the dynamic gas balance at the fusion front where formed grain is melted to dense fused silica.

Abstract: A silica glass crucible is manufactured by introducing into a rotating crucible mold bulk silica grain to form a bulky wall including a bottom wall and a side wall. After heating the interior of the mold to begin to fuse the bulk silica grains, an inner silica grain, doped with aluminum, is introduced. The heat at least partially melts the inner silica grain, allowing it to fuse to the wall to form an inner layer. The crucible is cooled, the fused silica grains forming nuclei of crystalline silica within the inner layer.

Abstract: A silica glass crucible is disclosed comprising an aluminum-doped inner wall layer. An aluminum-doped layer can be formed on an outer wall portion. The inner layer is non-homogeneously doped with aluminum to promote silica crystallization. The non-homogeneous silica grain mixture contains aluminum and can be aluminum-doped and aluminum-free silica grains or, alternatively, aluminum-coated coarse quartz grain.

Abstract: A silica glass crucible is disclosed comprising a barium-doped inner wall layer. The crucible is made by introducing into a rotating crucible mold bulk silica grain to form a bulky wall. After heating the interior of the mold to fuse the bulk silica grains, an inner silica grain, doped with barium, is introduced. The heat at least partially melts the inner silica grain, allowing it to fuse to the wall to form an inner layer. The inner layer of the crucible crystallizes when used in a CZ process, extending the operating life of the crucible.

Abstract: A silica glass crucible is disclosed comprising a barium-doped inner wall layer. The crucible is made by introducing into a rotating crucible mold bulk silica grain to form a bulky wall. After heating the interior of the mold to fuse the bulk silica grains, an inner silica grain, doped with barium, is introduced. The heat at least partially melts the inner silica grain, allowing it to fuse to the wall to form an inner layer. The inner layer of the crucible crystallizes when used in a CZ process, extending the operating life of the crucible.

Abstract: A silica glass crucible is disclosed comprising a barium-doped inner wall layer. The crucible is made by introducing into a rotating crucible mold bulk silica grain to form a bulky wall. After heating the interior of the mold to fuse the bulk silica grains, an inner silica grain, doped with barium, is introduced. The heat at least partially melts the inner silica grain, allowing it to fuse to the wall to form an inner layer. The inner layer of the crucible crystallizes when used in a CZ process, extending the operating life of the crucible.

Abstract: Silica crucibles containing an inner layer which is substantially pure and substantially bubble-free and methods for making such crucibles. The inner layer is also substantially stable against roughening and spot devitrification. The inner layer is formed by making a web structure which is then converted to a continuous layer, thereby minimizing or eliminating bubble formation. The inner layer is also formed using a gettering agent which getters alkaline and alkaline-earth elements while the inner layer is formed. The alkaline and alkaline-earth elements are gettered on an innermost portion of the inner layer which is later removed, leaving an inner layer with relatively few impurities. When used in a CZ-crystal growing process, the inner surface of the crucible remains smooth and substantially no bubbles grow in the inner layer.

Abstract: A silica glass crucible is disclosed comprising an aluminum-doped inner wall layer. An aluminum-doped layer can be formed on an outer wall portion. The inner layer is non-homogeneously doped with aluminum to promote silica crystallization. The non-homogeneous silica grain mixture contains aluminum and can be aluminum-doped and aluminum-free silica grains or, alternatively, aluminum-coated coarse quartz grain.

Abstract: A crucible adapted for use in formation of a silicon crystal comprises a crucible wall including a bottom wall and a side wall. An inner layer is formed on an inner portion of the crucible wall and has distributed therein a crystallization agent containing an element selected from the group consisting of barium, aluminum, titanium and strontium.

Abstract: Silica crucibles containing an inner layer which is substantially pure and substantially bubble-free and methods for making such crucibles. The inner layer is also substantially stable against roughening and spot devitrification. The inner layer is formed by making a web structure which is then converted to a continuous layer, thereby minimizing or eliminating bubble formation. The inner layer is also formed using a gettering agent which getters alkaline and alkaline-earth elements while the inner layer is formed. The alkaline and alkaline-earth elements are gettered on an innermost portion of the inner layer which is later removed, leaving an inner layer with relatively few impurities. When used in a CZ-crystal growing process, the inner surface of the crucible remains smooth and substantially no bubbles grow in the inner layer.

Abstract: Provided are high-purity quartz glass having a high purity, in particular, with little zirconium (Zr) and manufactured at low costs from natural quartz as the starting material and a method for the preparation thereof.

Abstract: An analytical method for the quantitative determination of the impurities in silicon dioxide by which trace amounts of hardly soluble impurities contained in silicon dioxide can be reliably decomposed and converted into a solution so that the contents of all of the impurities contained in silicon dioxide or, in particular, zirconium in a natural quartz powder can be accurately determined. Silicon dioxide is decomposed with hydrofluoric acid or an acid mixture of hydrofluoric acid and another inorganic acid to give a decomposition solution which is, as such or after admixture with another inorganic acid, subjected to evaporation to dryness and the residue is heated to cause fusion with addition of a salt or hydroxide of an alkali metal followed by dissolution of the salt or hydroxide of an alkali metal with pure water or with an aqueous solution of an inorganic acid to give an aqueous solution which is subjected to quantitative analysis of the impurities therein.

Abstract: A silica glass member shows a glassy carbon coating wherein a surface of a silica glass substrate of the silica glass member shows a mean surface roughness (R.sub.a) in a range of 0.03 .mu.m to 2 .mu.m and it is coated with a glassy carbon coating. The member is manufactured by chemically roughening the substrate to a surface roughness in the above recited range; coating the surface of the silica glass substrate with an organic raw material containing carbon, curing and thereafter carbonizing the film of the organic raw material by forming a glassy carbon coating.

Abstract: An improved method is proposed for the preparation of a semiconductor silicon single crystal of N-type by the Czochralski process, which is free from the problem of occurrence of delayed OSFs as defects in the single crystal even after prolonged storage at room temperature based on the discovery that presence of a certain amount of aluminum in the melt of silicon contained in a fused silica glass crucible acts to suppress occurrence of delayed OSFs as a type of defects in the single crystal while copper as an impurity acts adversely in this regard. With a known fact that an about 30 .mu.m thick inner surface layer of the crucible is melted down into the silicon melt during the single crystal pulling-up process, namely, the invention proposes use of a crucible of which the inner surface layer of 30 .mu.m thickness contains aluminum in an average concentration of 40 to 500 ppm by weight while the content of copper is as low as possible not to exceed 0.5 ppb by weight.

Abstract: An improved method is proposed for the preparation of a semiconductor silicon single crystal of N-type by the Czochralski process, which is free from the problem of occurrence of delayed OSFs as defects in the single crystal even after prolonged storage at room temperature based on the discovery that presence of a certain amount of aluminum in the melt of silicon contained in a fused silica glass crucible acts to suppress occurrence of delayed OSFs as a type of defects in the single crystal while copper as an impurity acts adversely in this regard. With a known fact that an about 30 .mu.m thick inner surface layer of the crucible is melted down into the silicon melt during the single crystal pulling-up process, namely, the invention proposes use of a crucible of which the inner surface layer of 30 .mu.m thickness contains aluminum in an average concentration of 40 to 500 ppm by weight while the content of copper is as low as possible not to exceed 0.5 ppb by weight.