Silica crucible with inner layer crystallizer and method

#The present invention is related to the field of silica crucibles, and more specifically to a silica crucible having a multi-layer wall in which one or more of the wall layers are doped with barium.

#The Czochralski (CZ) process is well-known in the art for production of ingots of single crystalline silicon, from which silicon wafers are made for use in the semiconductor industry.

#In a CZ process, metallic silicon is charged in a silica glass crucible housed within a susceptor. The charge is then heated by a heater surrounding the susceptor to melt the charged silicon. A single silicon crystal is pulled from the silicon melt at or near the melting temperature of silicon.

#FIG. 1 is a cross-sectional view of one embodiment of a silica glass crucible constructed according to the present disclosure.

#FIG. 2 is an enlarged, partial cross-sectional view of the wall of the silica glass crucible shown in FIG. 1.

#FIG. 3 is an enlarged, partial cross-sectional view of the wall of a second embodiment of a silica glass crucible constructed according to the present disclosure.

#In more detail, the present disclosure provides a silica glass crucible suitable for use in a CZ process. One embodiment of the crucible is shown in FIGS. 1-2. A silica glass crucible 1 has a wall 10 defining an interior cavity 12. The wall 10 comprises a side portion 10a and bottom portion.

#The side portion 10a of this embodiment comprises a bulk layer 14 of pure silica and an inner layer 16 formed on the inner portion of the wall. The bulk layer 14 generally is a translucent glass layer consisting essentially of silica. The inner layer 16 is comprised of fused doped silica.

#The inner layer 16 in the embodiment of FIGS. 1-2 is doped with barium in the range of 5-150 ppm, and preferably 15-75 ppm. In the illustrated embodiment, the inner layer has a thickness in the range of 0.2 mm-1.0 mm.