US 8,317,919 B2Granted

System for continuous growing of monocrystalline silicon

AssigneeSolaicx, Inc.

InventorDavid L Bender

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Abstract

An improved system based on the Czochralski process for continuous growth of a single crystal ingot comprises a low aspect ratio, large diameter, and substantially flat crucible, including an optional weir surrounding the crystal. The low aspect ratio crucible substantially eliminates convection currents and reduces oxygen content in a finished single crystal silicon ingot. A separate level controlled silicon pre-melting chamber provides a continuous source of molten silicon to the growth crucible advantageously eliminating the need for vertical travel and a crucible raising system during the crystal pulling process. A plurality of heaters beneath the crucible establish corresponding thermal zones across the melt. Thermal output of the heaters is individually controlled for providing an optimal thermal distribution across the melt and at the crystal/melt interface for improved crystal growth. Multiple crystal pulling chambers are provided for continuous processing and high throughput.

Claims3

Dependent claims

A system for achieving improved level control for continuously replenishing a melt of crystalline feedstock in a crucible for continuous CZ crystal growth, wherein an ingot is pulled from a respective seed crystal positioned at a melt/crystal interface in the crucible comprising:

a weight sensor means attached for weighing the crucible and for converting a load or weight exerted by the crucible into output signals representative of that sensed load or weight;
a controller communicatively linked with the weight sensor means for receiving output signals from the weight sensor representative of the weight of the crucible, for determining the weight of the growth crucible both empty and with a desired depth of melt at the crystal growth interface, and for providing activation signals over a second communication link to a dispenser for selectively providing silicon feedstock to the crucible, wherein the controller further comprises a computer means for determining activation of the dispenser based on a desired depth D of melt in the crucible according to the following relationship:
D=(W−Wt)/(π*R exponent 2*r);
where W is the total weight of the crucible containing melt;
Wt is the weight of the crucible measured empty;
R is the internal radius of the crucible;
and r is the density of liquid silicon;
and
a source of silicon feedstock connected to the dispenser, such that the dispenser, in response to the output signals from the controller, releases a predetermined amount of solid silicon feedstock into the crucible to maintain the melt level at the growth/crystal interface at a desired depth.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/525,824Filed 25 Feb 2005
Published: US 2008/0134958 A112 Jun 2008
Granted: 27 Nov 2012
Term ends: Not estimatedThe source records don’t support an estimate.

Classification22 codes

C30B 15/12
Crucibles or containers for supporting the melt: double crucible methods
C30B 15/002
Single-crystal growth by pulling from a melt, e.g. Czochralski method: continuous growth
C30B 15/02
Single-crystal growth by pulling from a melt, e.g. Czochralski method: adding crystallising materials or reactants forming it in situ to the melt
C30B 15/04
Adding crystallising materials or reactants forming it in situ to the melt: adding doping materials, e.g. for n-p-junction