Side feed system for Czochralski growth of silicon ingots
View Patent ↗A Czochralski growth system is described comprising a growth chamber, a feed port, and a feed chamber comprising a container for feedstock and a feeder. The feed port is disposed in at least one side wall of the growth chamber, and the feed chamber is attached to the growth chamber at the feed port. The feeder is insertable into the growth chamber through the feed port and supplies the feedstock into the growth chamber. Preferably this system can be used for producing silicon ingots using a continuous Czochralski method.
1. A Czochralski growth system, comprising:
a growth chamber comprising a crucible, at least one sidewall, a top wall, a pedestal for supporting the crucible, a drop box fixedly mounted to an inside of the growth chamber, and a pull mechanism for retractably supporting a seed for contacting a melt contained in the crucible, wherein the crucible comprises an inner zone positioned under the pull mechanism and an annular outer zone in fluid communication with the inner zone and disposed under a spout of the drop box;
a feed port positioned in the at least one sidewall of the growth chamber so that feedstock enters the growth chamber having overall path of delivery of the feedstock of between 0° and about 20° from horizontal at a center of the feed port and into the outer zone of the crucible; and
a feed chamber attached to the growth chamber at the feed port, the feed chamber comprising a feed hopper, a funnel spout for the feedstock and a feeder insertable into the growth chamber through the feed port to supply the feedstock into the growth chamber.
2. The Czochralski growth system of claim 1 , wherein the feed chamber further comprises an isolation valve.
3. The Czochralski growth system of claim 2 , wherein the isolation valve is between the feed hopper and the feeder.
4. The Czochralski growth system of claim 2 , wherein the isolation valve is a gate valve with an expandable water-cooled gate.
5. The Czochralski growth system of claim 1 , wherein the drop box comprises a horizontally extending receiving section and a chute having a sloping bottom for receiving the feedstock from the feeder, and a spout positioned over the crucible.
6. The Czochralski growth system of claim 5 , wherein the sloping bottom is inclined at an angle of between about 30° and about 60°.
7. The Czochralski growth system of claim 1 , wherein the feeder comprises a feeder pan having a receiving section for receiving the feedstock from an opening of the funnel spout of the feed hopper and an injector section connected to and having a cross section smaller than the receiving section and insertable through the feed port into the growth chamber.
8. The Czochralski growth system of claim 7 , wherein the injector section has a concave bottom.
9. The Czochralski growth system of claim 8 , wherein the concave bottom has a V shape with walls oppositely inclined from vertical at between about 30° and about 60°.
10. The Czochralski growth system of claim 1 , wherein the growth system does not comprise an isolation valve.