Apparatus and process for producing a crystal of semiconductor material

Patent metadata

Field	Value
Publication number	US-9828693-B2
Application number	US-201514711942-A
Country	US
Kind code	B2
Filing date	May 14, 2015
Priority date	Jun 6, 2014
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

A crystal of semiconductor material is produced in an apparatus having a crucible with a crucible bottom and a crucible wall, the crucible bottom having a top surface, an underside, and a multitude of openings disposed between the crucible wall and a center of the crucible bottom, and elevations disposed on the top surface and the underside of the crucible bottom; and an induction heating coil disposed below the crucible for melting semiconductor material and stabilizing a melt of semiconductor material covering a growing crystal of semiconductor material. The growth process comprises generating a bed of a semiconductor material feed on the top surface of the crucible bottom and melting semiconductor material on the bed using the induction heating coil.

First claim

What is claimed is:

1. An apparatus for producing a crystal of semiconductor material, comprising
a crucible comprising a crucible bottom and a crucible wall, the crucible bottom having a top surface, an underside, a central downward projection and a multitude of openings through the crucible bottom disposed between the crucible wall and a center of the crucible bottom, the openings located between elevations disposed on the top surface and the underside of the crucible bottom; wherein the openings and elevations facilitate a flow of molten semiconductor material from above the crucible to its underside; and
an induction heating coil for melting semiconductor material and stabilizing a melt of semiconductor material covering a growing crystal of semiconductor material disposed below the crucible, the induction heating coil located below the underside of the crucible bottom and the multiplicity of holes in the crucible bottom, the induction coil having a central hole suitable for enclosing a melt zone of a growing crystal.

2. The apparatus of claim 1 , wherein the elevations extend along trajectories forming circular, spiral, rhombic or chequered patterns.

3. The apparatus of claim 2 , wherein the middles of adjacent elevations, disposed along trajectories which do not cross, have a distance between them of not less than 2 mm and not more than 15 mm.

4. The apparatus of claim 1 , wherein on the underside of the crucible bottom in the center of the crucible bottom the projection which projects downwards is disposed above the central hole of the induction heating coil.

5. The apparatus of claim 2 , wherein on the underside of the crucible bottom in the center of the crucible bottom the projection which projects downwards is disposed above the central hole of the induction heating coil.

6. The apparatus of claim 3 , wherein on the underside of the crucible bottom in the center of the crucible bottom the projection which projects downwards is disposed above the central hole of the induction heating coil.

7. The apparatus of claim 1 , wherein the top surface and the underside of the crucible bottom comprise a ceramic material.

8. A process for producing a crystal of semiconductor material, comprising
providing an apparatus comprising;
a crucible having a crucible bottom and a crucible wall, the crucible bottom having a top surface and an underside and a multitude of openings disposed in the crucible bottom between the crucible wall and a center of the crucible bottom; elevations disposed on the top surface and on the underside of the crucible bottom; and an induction heating coil for melting semiconductor material and stabilizing a melt of semiconductor material covering a growing crystal of semiconductor material disposed below the crucible;
generating a bed of a semiconductor material feed on the top surface of the crucible bottom;
melting semiconductor material feed of the bed with the induction heating coil and channelling the molten semiconductor material from the top surface of the crucible bottom through the multitude of openings in the crucible bottom to the underside of the crucible bottom, the molten semiconductor material flowing underneath the elevations on the underside of the crucible bottom, to a melt which covers a growing crystal of semiconductor material and is a region of a melt zone.

9. The process of claim 8 , further comprising blocking the openings in the crucible bottom with semiconductor material of the bed or with solidified semiconductor material prior to melting semiconductor material feed of the bed.

10. The process of claim 8 , wherein the bed of semiconductor material feed comprises granules of semiconductor material, chunks of semiconductor material, or a mixture of granules and chunks of semiconductor material.

11. The process of claim 8 , further comprising replenishing the bed with further feed by allowing further feed to flow down onto the bed.

12. The process of claim 8 , wherein the semiconductor material comprises silicon.

13. The process of claim 8 , wherein the crystal is monocrystalline or polycrystalline.

14. The process of claim 8 , wherein the crystal has a circular, rectangular or square cross section.

15. The process of claim 11 , wherein the step of replenishing takes place during crystal growth.

16. The process of claim 8 , wherein the elevations have a height difference between the highest point of the elevation and the edge of an adjacent opening of from 0.1 mm to 5 mm.

17. The process of claim 8 , wherein the elevations have a height difference between the highest point of the elevation and the edge of an adjacent opening of from 0.5 mm to 3 mm.

18. The process of claim 8 , wherein openings of the multitude of openings are located between adjacent concentric elevations in a circular pattern.

19. The process of claim 8 , wherein the induction heating coil is in the form of a hollow flat ring, and a melt zone of a growing crystal is within a central opening of the induction coil.

20. The process of claim 8 , wherein the apparatus has a central downwardly projecting extension on the underside of the crucible bottom, and the melt zone is located below the central downwardly extending projection.

Assignees

• Siltronic Ag

Inventors

• Brenninger Georg
• Raming Georg

Classifications

• C30B15/12

  Double crucible methods · CPC title

• C30B11/001

  Continuous growth · CPC title

• C30B11/10

  Solid or liquid components, e.g. Verneuil method · CPC title

• C30B11/003

  Heating or cooling of the melt or the crystallised material · CPC title

• C30B15/02

  adding crystallising materials or reactants forming it in situ to the melt · CPC title