Accelerated testing for evaluating bubble quality within quartz glass crucibles used for manufacturing silicon single crystal ingots

To verify the quality of bubbles during the use of quartz glass crucibles (QC), an appropriate accelerated testing method was proposed. The bubble state of discarded waste crucibles obtained from actual Czochralski (Cz) processes was analyzed, and optimal heat treatment conditions were suggested by varying temperature, pressure, and time using the QC test piece. By subjecting the samples to heat treatment at 1450 degrees C, 0.4 Torr, and 40 hours, it was possible to control the bubble size and density to a similar level as those generated in the actual Cz process. In particular, by selecting a relatively lower pressure of 0.4 Torr compared to the typical range of 10 similar to 20 Torr applied in the Cz process, the time required for accelerated bubble formation testing could be reduced. However, it was determined that increasing the heat treatment temperature to 1550 degrees C led to the phenomenon of Ostwald ripening, resulting in larger bubbles and a rapid decrease in density. Therefore, it was concluded that it was not a suitable condition for the desired bake test.