Methods for producing crucibles with a reduced amount of bubbles
View Patent ↗Methods for producing crucibles for holding molten material that contain a reduced amount of gas pockets are disclosed. The methods may involve use of molten silica that may be outgassed prior to or during formation of the crucible. Crucibles produced from such methods and ingots and wafers that are produced from crucibles with a reduced amount of gas pockets are also disclosed.
1. A process for producing a crucible for holding molten material, the crucible having a base and one or more sidewalls, the process comprising contacting a silicon and oxygen-containing gas with a crucible-shaped substrate having a base and one or more sidewalls to deposit silica onto the substrate, deposited silica continuously growing to form a surface layer of silica of at least about 1 mm.
2. The process as set forth in claim 1 wherein silica continuously grows to form a surface layer of silica of at least about 2 mm.
3. The process as set forth in claim 1 wherein the silicon and oxygen-containing gas is produced by oxidizing a silicon-containing gas or liquid.
4. The process as set forth in claim 3 wherein the silicon-containing gas or liquid used to produce the silicon and oxygen-containing gas is selected from the group consisting of silane, halosilane and tetraethoxysilane.
5. The process as set forth in claim 1 wherein the surface layer comprises at least about 95 wt % silica.
6. The process as set forth in claim 1 wherein the substrate comprises at least about 10 wt % silica.
7. The process as set forth in claim 1 wherein the silica surface layer has less than about 70 bubbles with a diameter of at least about 14 μm per cm 3 .
8. The process as set forth in claim 1 wherein the crucible is substantially free of bubbles with a diameter of at least about 14 μm.
9. The process as set forth in claim 1 wherein at least about 75% of the bubbles in the silica surface layer have a nominal diameter of less than about 14 μm.
10. The process as set forth in claim 1 wherein the substrate is composed of fused silica.
11. A process for producing a crucible for holding molten material, the crucible comprising silica and having a base and one or more sidewalls, the process comprising shaping a plate or tube into the form of a crucible having a base and one or more sidewalls, the plate or tube comprising silica, the plate or tube having less than about 70 bubbles with a diameter of at least about 14 μm per cm 3 .
12. The process as set forth in claim 11 wherein the silica surface layer contains less than about 50 bubbles with a diameter of at least about 14 μm per cm 3 .
13. The process as set forth in claim 11 wherein the silica surface layer is substantially free of bubbles with a diameter of at least about 14 μm.
14. The process as set forth in claim 11 wherein the plate or tube is shaped into the form of a crucible while heating the plate or tube.
15. The process as set forth in claim 11 wherein the tube has an end portion that is shaped to form the base of the crucible.
16. The process as set forth in claim 11 wherein the plate or tube comprises at least about 10 wt % silica.
17. The process as set forth in claim 11 wherein the crucible has a thickness of at least about 6 mm.
18. The process as set forth in claim 1 wherein silica continuously grows to form a surface layer of silica of at least about 4 mm.
19. The process as set forth in claim 1 wherein the silica surface layer has less than about 10 bubbles with a diameter of at least about 14 μm per cm 3 .
20. The process as set forth in claim 11 wherein the plate or tube comprises at least about 95 wt % silica.