Czochralski crystal growth process furnace that maintains constant melt line orientation and method of operation

A Czochralski (“CZ”) crystal growth furnace comprising:

• a base;
• a heater capable of generating a generally annular shaped heating zone, coupled to the base;
• a pedestal moveable relative to the heating zone;
• a pedestal motion driver coupled to the pedestal and base, for moving the pedestal relative to the heating zone;
• a crucible within the heating zone and coupled to the pedestal, capable of retaining a volume of molten crystal growth material forming a melt line oriented in a designated position within the heating zone;
• a seed growth rod retractable from the crucible, for forming a crystal boule thereon proximal the melt line from the molten crystal growth material, the melt line lowering within the crucible as the boule grows and is retracted;
• a seed rod motion driver coupled to the seed growth rod for retracting the seed control rod from the crucible, and a seed rod motion controller coupled to the seed rod motion driver, for causing seed rod retraction;
• a seed rod motion sensor in communication with the seed rod motion controller, the seed rod motion controller causing seed rod movement by the seed rod motion driver at least based in part on seed rod motion information received from the seed rod motion sensor;
• a boule weight sensor for sensing boule weight;
• a pedestal motion controller coupled to the boule weight sensor and the pedestal motion driver, for causing pedestal movement relative to the heater to be based at least in part on sensed boule weight as well as synchronized with boule extraction, so that the melt line maintains the designated position during boule retraction;
• and
• a pedestal motion sensor in communication with the pedestal motion controller, the pedestal controller causing pedestal movement by the pedestal motion driver at least based in part on pedestal motion information received from the pedestal motion sensor.

A Czochralski (“CZ”) crystal growth furnace comprising:

• a base;
• a heater capable of generating a generally annular shaped heating zone, coupled to the base;
• a pedestal, coupled to the base, moveable relative to the heating zone;
• a crucible within the heating zone and coupled to the pedestal, capable of retaining a volume of molten crystal growth material forming a melt line oriented in a designated position within the heating zone;
• a seed growth rod retractable from the crucible, for forming a crystal boule thereon proximal the melt line from the molten crystal growth material, the melt line lowering within the crucible as the boule grows and is retracted;
• means for retracting the seed growth rod from the crucible;
• a boule weight sensor for sensing boule weight;
• and
• means for causing pedestal movement relative to the heater based at least in part on boule weight, coupled to the boule weight sensor, and synchronized with the means for retracting the seed growth rod, so that the melt line is maintained at the designated position during boule growth.

An improved method for growing crystals with a Czochralski growth furnace, comprising:

• placing a crucible within a Czochralski growth furnace heater heating zone;
• maintaining a molten volume of crystal growth material forming a melt line in the crucible with the heater;
• orienting the crucible melt line in a designated position within the heating zone;
• retracting a crystal growth boule from the crucible with a seed rod, and thereby lowering the crucible melt line as the boule grows and consumes more of the crucible's melted contents;
• sensing boule weight;
• and
• maintaining the melt line in the designated position within the heating zone by causing relative motion between the crucible and heater during the boule retracting step, based at least in part on sensed boule weight.

An improved method for growing crystals with a Czochralski growth furnace, comprising:

• placing a crucible within a Czochralski growth furnace heater heating zone on a pedestal that is moveable relative to the heating zone;
• maintaining a molten volume of crystal growth material forming a melt line in the crucible with the heater;
• orienting the crucible melt line in a designated position within the heating zone;
• retracting a crystal growth boule from the crucible with a seed rod, and thereby lowering the crucible melt line as the boule grows and consumes more of the crucible's melted contents;
• sensing the boule weight;
• and
• maintaining the melt line in the designated position within the heating zone during the retracting step by contemporaneously moving the crucible relative to the heater with the pedestal, the moving based at least in part on sensed boule weight.

An improved method for growing crystals with a Czochralski growth furnace, comprising:

• placing a crucible within a Czochralski growth furnace heater heating zone;
• maintaining a molten volume of crystal growth material forming a melt line in the crucible with the heater;
• orienting the crucible melt line in a designated position within the heating zone;
• retracting a crystal growth boule from the crucible with a seed rod coupled to a seed rod retraction mechanism, and thereby lowering the crucible melt line as the boule grows and consumes more of the crucible's melted contents;
• maintaining a fixed relative orientation of the crucible and seed rod retraction mechanism by coupling both to a gantry;
• and
• maintaining the melt line in the designated position within the heating zone by causing relative motion between the crucible and heater during the boule retracting step.

A Czochralski (“CZ”) crystal growth furnace comprising:

• a base;
• a heater capable of generating a generally annular shaped heating zone;
• a crucible oriented within the heating zone, capable of retaining a volume of molten crystal growth material forming a melt line oriented in a designated position within the heating zone;
• a pedestal coupled to and moveable relative to the base;
• a pedestal motion driver coupled to the pedestal and base;
• a seed growth rod retractable from the crucible with a seed rod retraction mechanism, for forming a crystal boule thereon proximal the melt line from the molten crystal growth material, the melt line lowering within the crucible as the boule grows and is retracted;
• a gantry coupling the pedestal and seed rod retraction mechanism in fixed relative orientation;
• and
• a pedestal motion controller coupled to the pedestal motion driver, for relative motion between the heater and crucible, so that the melt line maintains the designated position during boule growth.