Continuous czochralski method and apparatus
View Patent ↗The present invention relates to a Czochralski growth apparatus and method, preferably a continuous Czochralski growth apparatus and method, in which solid feedstock provided from a delivery system during ingot growth is substantially prevented from entering the growth zone of a crucible. In this way, an ingot having exceptionally consistent properties is produced.
1. A Czochralski growth apparatus comprising
a crucible having at least one wall separating an inner growth zone and an outer feed zone, the wall having at least one opening providing restricted fluid communication between the inner growth zone and the outer feed zone;
a solid feedstock delivery system comprising a feeder having a delivery point overhanging the outer feed zone of the crucible and delivering solid feedstock comprising silicon therein;
at least one particle blocking device substantially preventing the solid feedstock from entering the inner growth zone of the crucible; and
an thermally-insulated shield positioned above the inner growth zone of the crucible, wherein the thermally-insulated shield and the wall are separated by a gap,
wherein the particle blocking device prevents the solid feedstock from passing through the gap, and
wherein the particle blocking device includes a vertical segment positioned at the wall of the crucible and extending to a position adjacent to the thermally-insulated shield.
2. The Czochralski growth apparatus of claim 1 , wherein the particle blocking device is a particle shield at least partially covering the inner growth zone of the crucible.
3. The Czochralski growth apparatus of claim 1 , wherein the particle blocking device is a particle shield positioned on the wall of the crucible projecting into the inner growth zone.
4. The Czochralski growth apparatus of claim 1 , wherein the particle blocking device is a particle shield positioned at the opening of the wall of the crucible.
5. The Czochralski growth apparatus of claim 1 , wherein the particle blocking device is a particle shield positioned at least partially around or within the delivery point of the feeder.
6. The Czochralski growth apparatus of claim 5 , wherein the particle blocking device is a sleeve positioned within the feeder, the sleeve extending at least partially below the delivery point of the feeder and having a lower edge positioned within the outer feed zone of the crucible.
7. The Czochralski growth apparatus of claim 1 , wherein the particle blocking device is an insulated housing circumferentially positioned around the thermally-insulated shield.
8. The Czochralski growth apparatus of claim 7 , wherein the insulated housing is positioned at least partially above the outer feed zone.
9. The Czochralski growth apparatus of claim 7 , wherein the insulated housing is positioned at least partially above the inner growth zone.
10. The Czochralski growth apparatus of claim 7 , wherein the insulated housing is externally positioned around the thermally-insulated shield.
11. The Czochralski growth apparatus of claim 7 , wherein the thermally-insulated shield has a lower edge positioned within the inner growth zone below an upper edge of the wall, and wherein the insulated housing is positioned around the lower edge of the thermally-insulated shield.
12. A method of Czochralski growth of a silicon ingot comprising the steps of:
i) providing a crucible in a Czochralski growth apparatus having at least one wall separating an inner growth zone and an outer feed zone, the wall having at least one opening providing restricted fluid communication between the inner growth zone and the outer feed zone;
ii) providing a solid precharge comprising silicon into the inner growth zone and the outer feed zone of the crucible;
iii) melting the solid precharge in the inner growth zone and in the outer feed zone;
iv) initiating growth of the silicon ingot from the inner growth zone;
v) delivering solid feedstock comprising silicon from a silicon delivery system into the outer feed zone while growing the silicon ingot, the silicon delivery system comprising a feeder having a delivery point overhanging the outer feed zone of the crucible and delivering solid silicon therein; and
vi) removing the silicon ingot from the Czochralski growth apparatus; wherein the Czochralski growth apparatus comprises at least one particle blocking device substantially preventing the solid silicon from entering the inner growth zone of the crucible, and a thermally-insulated shield positioned above the inner growth zone of the crucible,
wherein the thermally-insulated shield and the wall are separated by a gap, and the particle blocking device prevents the solid feedstock from passing through the gap, and
wherein the particle blocking device is a particle shield and includes a vertical segment positioned at the wall of the crucible and extending to a position adjacent to the thermally-insulated shield.
13. The method of claim 12 , wherein the solid feedstock further comprises at least one dopant material.
14. The method of claim 13 , wherein the dopant material is phosphorus, boron, gallium, indium, or aluminum, arsenic, antimony.
15. The method of claim 12 , wherein the inner growth zone and the outer feed zone comprise a solid precharge comprising silicon to be melted therein.
16. The method of claim 15 , wherein the solid precharge in the inner growth zone, the outer feed zone, or both further comprises at least one dopant material.
17. The method of claim 12 , wherein the Czochralski growth apparatus is a continuous Czochralski growth apparatus.