Axial Gradient Transport (AGT) Growth Process and Apparatus Utilizing Resistive Heating

Patent metadata

Field	Value
Publication number	US-2016097143-A1
Application number	US-201514967926-A
Country	US
Kind code	A1
Filing date	Dec 14, 2015
Priority date	Dec 8, 2008
Publication date	Apr 7, 2016
Grant date	—

Abstract

A crucible has a first resistance heater is disposed in spaced relation above the top of the crucible and a second resistance heater with a first resistive section disposed in spaced relation beneath the bottom of the crucible and with a second resistive section disposed in spaced relation around the outside of the side of the crucible. The crucible is charged with a seed crystal at the top of an interior of the crucible and a source material in the interior of the crucible in spaced relation between the seed crystal and the bottom of the crucible. Electrical power of a sufficient extent is applied to the first and second resistance heaters to create in the interior of the crucible a temperature gradient of sufficient temperature to cause the source material to sublimate and condense on the seed crystal thereby forming a growing crystal.

First claim

The invention claimed is:

1 . An apparatus for axial gradient growth of silicon carbide by sublimation comprising:
a crucible having a top, a bottom and a side that extends between the top of the crucible and the bottom of the crucible, said crucible adapted to support a seed crystal at the top of an interior of the crucible and a source material in the interior of the crucible in spaced relation between the seed crystal and the bottom of the crucible, the space between the source material and the bottom of the crucible defining a cavity in the interior of the crucible; a first resistance heater disposed in spaced relation above the top of the crucible; and a second resistance heater having a first section disposed in spaced relation beneath the bottom of the crucible and a second section disposed in spaced relation around the outside of the side of the crucible.

2 . The apparatus of claim 1 , wherein the first and second resistance heaters are operative for PVT growing on the seed crystal disposed at the top of the interior of the crucible a growth crystal having a convex growth interface, wherein a ratio of a radius of curvature of the convex growth interface over a diameter of the grown crystal is between about 2 and about 4.

3 . The apparatus of claim 1 , wherein:
the top and bottom of the crucible are round; the first resistance heater is disk-shaped; and the first section of the second resistance heater is disk-shaped.

4 . The apparatus of claim 3 , wherein the first heater and the first section of the second resistance heater have outer diameters that are between 110% and 130%, inclusive, of the outer diameter of the respective top and bottom of the crucible.

5 . The apparatus of claim 3 , wherein the first resistance heater and the first section of the second resistance heater have central holes with a diameter between 25% and 75% of a diameter of the crucible.

6 . The apparatus of claim 1 , wherein:
the side of the crucible is cylindrical-shaped; and the second section of the second resistance heater is cylindrical-shaped.

7 . The apparatus of claim 6 , wherein the top of the second section of the second resistance heater is disposed at a position between 50% and 75% of a height of the crucible.

8 . The apparatus of claim 6 , wherein the inner diameter of the second section of the second resistance heater is spaced from the crucible by a radial distance between 10 mm and 25 mm.

9 . The apparatus of claim 1 , wherein the cavity has a height-to-diameter ratio between 0.2 and 1.

10 . An apparatus for axial gradient growth of silicon carbide by sublimation comprising:
a crucible having a top, a bottom and a side that extends between the top of the crucible and the bottom of the crucible, said crucible adapted to support a seed crystal at the top of an interior of the crucible and a source material in the interior of the crucible in spaced relation between the seed crystal and the bottom of the crucible and in contact with the side of the crucible, the space between the source material and the bottom of the crucible defining a cavity in the interior of the crucible; a first, disk-shaped resistance heater disposed in spaced relation above the top of the crucible; and a second, cup-shaped resistance heater having a first, disk-shaped section disposed in spaced relation beneath the bottom of the crucible and a second, cylindrical-shaped section disposed in spaced relation around the outside of the side of the crucible and extending from the first, disk-shaped section of the second resistance heater in the direction toward the first, disk-shaped resistance heater and terminating intermediate the top and the bottom of the crucible.

11 . The apparatus of claim 10 , wherein the first and second resistance heaters are operative for sublimation growing on the seed crystal disposed at the top of the interior of the crucible an SiC single crystal having a growth interface convex toward the bottom of the crucible, wherein a ratio of a radius of curvature of the convex growth interface over a diameter of the grown SiC single crystal is between 2 and 4.

12 . The apparatus of claim 10 , wherein the top and bottom of the crucible are round.

13 . The apparatus of claim 10 , wherein the side of the crucible is cylindrical-shaped.

14 . The apparatus of claim 12 , wherein the first heater and the first section of the second resistance heater have outer diameters that are between 110% and 130% of the outer diameter of the respective top and bottom of the crucible.

15 . The apparatus of claim 12 , wherein the first resistance heater and the first section of the second, cup-shaped resistance heater have central holes with a diameter between 25% and 75% of a diameter of the crucible.

16 . The apparatus of claim 10 , wherein the second, cylindrical-shaped section of the second, cup-shaped resistance heater extends from the first, disk-shaped section of the second resistance heater in the direction toward the first, disk-shaped resistance heater and terminates intermediate the top and the bottom of the crucible at a position between 50% and 75% of a height of the crucible.

17 . The apparatus of claim 10 , wherein the inner diameter of the second, cylindrical-shaped section of the second, cup-shaped resistance heater is spaced from the crucible by a radial distance between 10 mm and 25 mm.

18 . The apparatus of claim 10 , wherein the cavity in the interior of the crucible formed between the source material and the bottom of the crucible has a height-to-diameter ratio between 0.2 and 1.

Assignees

• Ii Vi Inc

Inventors

• Rengarajan Varatharajan
• Brouhard Bryan K
• Nolan Michael C
• Zwieback Ilya

Classifications

• C30B23/06 Primary

  Heating of the deposition chamber, the substrate or the materials to be evaporated · CPC title

• C30B29/36

  Carbides · CPC title

• C30B29/06

  Silicon · CPC title

• C30B15/14 Primary

  Heating of the melt or the crystallised materials · CPC title

• C30B15/10

  Crucibles or containers for supporting the melt · CPC title