Asymmetric thermal fields for excluding impurities in single crystal manufacturing device
Disclosed herein is a furnace and a method of growing a high temperature oxide crystal. The furnace includes a cylindrical furnace wall, an induction coil disposed within the cylindrical furnace wall, a quartz tube disposed within the induction coil, a refractory lining disposed within the quartz tube, and a crucible disposed within the refractory lining, the crucible including a melt therein. A lid placed on the crucible. An asymmetric configuration of at least one of the crucible, the refractory lining, the quartz tube, the induction coil and the lid within the cylindrical furnace wall creates a thermal gradient that causes a cold spot in the melt to migrate from a first location to a second location of the melt. A rod having a seed crystal at an end thereof is lowered into the crucible to draw a boule from the melt via the seed crystal from the first location.
1 . A furnace, comprising:
a cylindrical furnace wall defining a furnace central axis;
an induction coil disposed within the cylindrical furnace wall, the induction coil defining a coil central axis;
a quartz tube disposed within the induction coil, the quartz tubing defining a quartz central axis;
a refractory lining disposed within the quartz tube, the refractory lining defining a lining central axis, wherein at least one of the coil central axis, the quartz central axis and the lining central axis is placed at an eccentric location with respect to the furnace central axis of the cylindrical furnace;
a crucible disposed within the refractory lining, the crucible including a melt therein
wherein the eccentric location of at least one of the coil central axis, the quartz central axis and the lining central axis with respect to the furnace central axis creates a thermal gradient that causes a location in the melt at which the melt descends to the bottom of the crucible via convection to be away from the furnace central axis; and
a rod configured to draw a crystal from the melt at the furnace central axis to grow the crystal.
2 . The furnace of claim 1 , wherein the crucible central axis is eccentric from the furnace central axis.
3 . The furnace of claim 1 , wherein the refractory lining has a first side that is thicker than a second side opposite the first side.
4 . The furnace of claim 1 , wherein the quartz central axis is eccentric from the furnace central axis.
5 . The furnace of claim 1 , wherein the coil central axis is eccentric to the furnace central axis.
6 . The furnace of claim 1 , further comprising a hole in the refractory lining to one side of the crucible.
7 . The furnace of claim 1 , further comprising a finger placed against the quartz tube to one side of the crucible.
8 . The furnace of claim 1 , further comprising a lid placed on the crucible, wherein the eccentric location of at least one of the coil central axis, the quartz central axis, the lining central axis and the lid with respect to the furnace central axis creates the thermal gradient.
9 . The furnace of claim 8 , wherein the lid is placed asymmetrically with respect to the crucible.