METHOD FOR MANUFACTURING A SILICON CARBIDE SUBSTRATE FOR AN ELECTRICAL SILICON CARBIDE DEVICE, A SILICON CARBIDE SUBSTRATE AND AN ELECTRICAL SILICON CARBIDE DEVICE

• US 20140264374A1
• Filed: 03/14/2013
• Published: 09/18/2014
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Hecht, Christian, Rupp, Roland, Schulze, Hans-Joachim, Hoechbauer, Tobias
• Granted Patent: US 11,721,547 B2
• Time in Patent Office: Days
• US Class Current: 257/77
• CPC Class Codes: H01L 21/02529 Silicon carbide
• CPC Class Codes: H01L 21/76254 with separation/delamination along an ion implanted layer, e.g. Smart-cut, Unibond
• CPC Class Codes: H01L 29/1608 Silicon carbide

Abstract

A method for manufacturing a silicon carbide substrate for an electrical silicon carbide device includes providing a silicon carbide dispenser wafer including a silicon face and a carbon face and depositing a silicon carbide epitaxial layer on the silicon face. Further, the method includes implanting ions with a predefined energy characteristic forming an implant zone within the epitaxial layer, so that the ions are implanted with an average depth within the epitaxial layer corresponding to a designated thickness of an epitaxial layer of the silicon carbide substrate to be manufactured. Furthermore, the method comprises bonding an acceptor wafer onto the epitaxial layer so that the epitaxial layer is arranged between the dispenser wafer and the acceptor wafer. Further, the epitaxial layer is split along the implant zone so that a silicon carbide substrate represented by the acceptor wafer with an epitaxial layer with the designated thickness is obtained.

Claims

1. A method for manufacturing a silicon carbide substrate for an electrical silicon carbide device, the method comprising:

providing a silicon carbide dispenser wafer comprising a silicon face and a carbon face;

depositing a silicon carbide epitaxial layer on the silicon face of the dispenser wafer;

implanting ions with a predefined energy characteristic to form an implant zone within the silicon carbide epitaxial layer, wherein the ions are implanted with an average depth within the silicon carbide epitaxial layer corresponding to a designated thickness of an epitaxial layer of the silicon carbide substrate to be manufactured;

bonding an acceptor wafer onto the silicon carbide epitaxial layer, so that the silicon carbide epitaxial layer is arranged between the dispenser wafer and the acceptor wafer; and

splitting the silicon carbide epitaxial layer along the implant zone, so that a silicon carbide substrate represented by the acceptor wafer with an epitaxial layer having the designated thickness is obtained.

2. The method according to claim 1, wherein the splitting of the silicon carbide epitaxial layer comprises heating the silicon carbide epitaxial layer to a temperature between 600°

C. and 1300°

C.

3. The method according to claim 1, wherein the acceptor wafer is a tungsten wafer, a poly crystalline silicon carbide wafer, or a graphite wafer coated with silicon carbide.

4. The method according to claim 1, further comprising:

implanting ions in the remaining silicon carbide epitaxial layer on the dispenser wafer with another or the same predefined energy characteristic forming another implant zone within the remaining silicon carbide epitaxial layer, so that the ions are implanted with an average depth within the remaining silicon carbide epitaxial layer corresponding to an other or the same designated thickness of an epitaxial layer of a further silicon carbide substrate to be manufactured;

bonding another acceptor wafer onto the remaining silicon carbide epitaxial layer, so that the remaining silicon carbide epitaxial layer is arranged between the dispenser wafer and the further acceptor wafer; and

splitting the remaining silicon carbide epitaxial layer along the another implant zone, so that a further silicon carbide substrate represented by the further acceptor wafer with an epitaxial layer having the other or the same designated thickness is obtained.

5. The method according to claim 1, further comprising:

depositing further silicon carbide by epitaxy on the remaining silicon carbide epitaxial layer on the dispenser wafer;

implanting ions with another or the same predefined energy characteristic forming another implant zone within either the remaining silicon carbide epitaxial layer or the deposited further silicon carbide epitaxial layer, so that the ions are implanted with an average depth within the remaining silicon carbide epitaxial layer or the deposited further silicon carbide epitaxial layer corresponding to an other or the same designated thickness of an epitaxial layer a further silicon carbide substrate to be manufactured;

bonding another acceptor wafer onto the deposited further silicon carbide epitaxial layer, so that the deposited further silicon carbide epitaxial layer is arranged between the dispenser wafer and the further acceptor wafer; and

splitting the remaining silicon carbide epitaxial layer or the deposited further silicon carbide epitaxial layer along the implant zone, so that a further silicon carbide substrate represented by the further acceptor wafer with an epitaxial layer having the other or the same designated thickness is obtained.

6. The method according to claim 1, wherein the silicon carbide epitaxial layer is deposited so that the silicon carbide epitaxial layer comprises a dopant density of less than 1*10¹⁶ cm⁻

3.

7. The method according to claim 1, wherein the silicon carbide epitaxial layer is deposited so that the silicon carbide epitaxial layer comprises a dopant density of less than 1*10¹⁵ cm⁻

3.

8. The method according to claim 1, wherein the silicon carbide epitaxial layer is deposited so that the silicon carbide epitaxial layer comprises a dopant density between 1*10¹⁶ cm⁻

3 and 4*10¹⁵ cm<sup>−

3</sup>.

9. The method according to claim 1, further comprising implanting a designated dopant distribution within the silicon carbide epitaxial layer corresponding to a required dopant distribution at the silicon face of the silicon carbide epitaxial layer for an electrical silicon carbide device to be realized on the silicon carbide substrate to be manufactured at the carbon face.

10. The method according to claim 1, wherein the silicon carbide epitaxial layer is split, so that the epitaxial layer of the silicon carbide substrate with the designated thickness comprises a carbon face accessible for a manufacturing of an electrical silicon carbide device.

11. The method according to claim 1, wherein the predefined energy characteristic is selected so that the designated thickness of the epitaxial layer of the silicon carbide substrate to be manufactured is equal to or larger than a designated drift layer of an electrical silicon carbide device.

14. A method for manufacturing an electrical silicon carbide device, the method comprising:

providing or manufacturing a silicon carbide substrate manufactured according to claim 1; and

manufacturing the electrical silicon carbide device on the carbon face of the epitaxial layer of the silicon carbide substrate.

15. The method according to claim 14, further comprising:

attaching the silicon carbide substrate with the manufactured electrical silicon carbide device to a carrier wafer facing the electrical silicon carbide device; and

removing the acceptor wafer from the epitaxial layer comprising the electrical silicon carbide device attached to the carrier wafer.

16. The method according to claim 15, further comprising producing a back side metal layer on a back side of the epitaxial layer comprising the electrical silicon carbide device.

17. The method according to claim 14, wherein the electrical silicon carbide device comprises a blocking voltage above 500V.

18. The method according to claim 1, wherein ionized hydrogen atoms, ionized hydrogen molecules, an ionized noble gas or a combination of hydrogen ions and an ionized noble gas species are used for implanting ions with a predefined energy characteristic forming an implant zone within the epitaxial layer.

19. The method according to claim 18, wherein hydrogen atoms can be additionally in-diffused after the implantation step to reinforce the splitting process, if other ions than hydrogen are implanted.

12. A method for manufacturing a silicon carbide substrate for an electrical silicon carbide device, the method comprising:

providing a silicon carbide dispenser wafer comprising a silicon face and a carbon face, wherein the silicon face is formed by a surface of an epitaxial layer of the silicon carbide dispenser wafer; and

using a high energy ion cutting method to split the epitaxial layer along an implant zone, so that a silicon carbide substrate represented by an acceptor wafer bonded to the epitaxial layer of the silicon carbide dispenser wafer and an epitaxial layer with a designated thickness is obtained.

13. A method for manufacturing a silicon carbide substrate for an electrical silicon carbide device, the method comprising:

providing a silicon carbide dispenser wafer comprising a silicon face and a carbon face;

depositing a silicon carbide epitaxial layer on the silicon face of the dispenser wafer, so that the epitaxial layer comprises a dopant density of less than 1*10¹⁶ cm<sup>−

3</sup>;

implanting ions with a predefined energy characteristic to form an implant zone within the epitaxial layer, wherein the ions are implanted with an average depth within the silicon carbide epitaxial layer corresponding to a designated thickness of an epitaxial layer of the silicon carbide substrate to be manufactured;

bonding an acceptor wafer onto the silicon carbide epitaxial layer, so that the silicon carbide epitaxial layer is arranged between the dispenser wafer and the acceptor wafer; and

splitting the silicon carbide epitaxial layer along the implant zone by heating the epitaxial layer to a temperature between 600°

C. and 1300°

C., so that a silicon carbide substrate represented by the acceptor wafer with an epitaxial layer with the designated thickness is obtained.

20. A silicon carbide substrate comprising:

a carrier wafer being a tungsten wafer, a poly crystalline silicon carbide wafer, or a graphite wafer coated with silicon carbide; and

a silicon carbide epitaxial layer attached to the carrier wafer and comprising a carbon face opposing the carrier wafer and a silicon face facing the carrier wafer, so that an electrical silicon carbide device is manufacturable on the carbon face of the epitaxial layer.