Patent ID: 8317919

Claim:
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.