Silicon carbide device with trench gate

Patent metadata

Field	Value
Publication number	US-11552173-B2
Application number	US-202016986338-A
Country	US
Kind code	B2
Filing date	Aug 6, 2020
Priority date	Aug 14, 2019
Publication date	Jan 10, 2023
Grant date	Jan 10, 2023

Abstract

A silicon carbide device includes a stripe-shaped trench gate structure extending from a first surface into a silicon carbide body. The gate structure has a gate length along a lateral first direction. A bottom surface and an active first gate sidewall of the gate structure are connected via a first bottom edge of the gate structure. The silicon carbide device further includes at least one source region of a first conductivity type. A shielding region of a second conductivity type is in contact with the first bottom edge of the gate structure across at least 20% of the gate length.

First claim

What is claimed is:

1. A silicon carbide device, comprising:
an asymmetric transistor cell that includes a stripe-shaped trench gate structure extending from a first surface into a silicon carbide body, the gate structure having a gate length along a lateral first direction, a bottom surface and a first gate sidewall of the gate structure being connected via a first bottom edge of the gate structure;
at least one source region of a first conductivity type in contact with the first gate sidewall; and
a shielding region of a second conductivity type in contact with the first bottom edge of the gate structure across at least 20% of the gate length,
wherein no source regions of the first conductivity type are in contact with a second gate sidewall of the gate structure.

2. The silicon carbide device of claim 1 , wherein the shielding region is in contact with the first bottom edge across at least 30% of the gate length.

3. The silicon carbide device of claim 1 , wherein the shielding region comprises a top shielding portion and a deep shielding portion, wherein the top shielding portion is between the first surface and the deep shielding portion, and wherein the top shielding portion is in contact with the first bottom edge.

4. The silicon carbide device of claim 3 , wherein a first distance between the top shielding portion and the first gate sidewall is smaller than a second distance between the deep shielding portion and the first gate sidewall.

5. The silicon carbide device of claim 3 , wherein the top shielding portion comprises separation sections, wherein the separation sections are in contact with the first gate sidewall, and wherein each separation section laterally separates source regions formed along the first direction.

6. The silicon carbide device of claim 3 , wherein the top shielding portion comprises separation sections that are located between the source regions, and wherein along the first surface, the separation sections and the source regions cover a continuous part of the first gate sidewall of the gate structure.

7. The silicon carbide device of claim 3 , wherein the silicon carbide device comprises a first gate structure and a neighboring second gate structure, wherein the top shielding portion and the source regions of the first gate structure are arranged between the first gate sidewall of the first gate structure and a second gate sidewall of the second gate structure, and wherein at the first surface, an area between the first gate sidewall and the second gate sidewall is filled with the top shielding portion and the source regions.

8. The silicon carbide device of claim 3 , wherein the top shielding portion comprises separation sections, wherein along the first direction, a lateral dopant profile through a transition between one of the separation sections and one of the source regions comprises a plateau section.

9. The silicon carbide device of claim 3 , wherein the silicon carbide device comprises a first gate structure and a neighboring second gate structure, wherein the deep shielding portion comprises a deep section, wherein along a second direction the deep section is laterally separated from the first gate sidewall of the first gate structure, and wherein the deep section laterally overlaps with a second gate sidewall of the second gate structure.

10. The silicon carbide device of claim 9 , wherein the deep section forms a contiguous stripe with a longitudinal axis parallel to the first direction.

11. The silicon carbide device of claim 9 , wherein the deep section comprises a plurality of deep sub-sections, and wherein the deep sub-sections are laterally separated along the first direction.

12. The silicon carbide device of claim 3 , wherein a horizontal cross-section of the deep shielding portion comprises a grid with grid openings, and wherein each grid opening encloses at least a portion of one of the source regions.

13. The silicon carbide device of claim 1 , wherein the silicon carbide body comprises a body region of the second conductivity type and a current spread region of the first conductivity type, and wherein the body region separates the source region and the current spread region.

14. The silicon carbide device of claim 1 , wherein the silicon carbide body comprises a drift structure between the gate structures and a second surface of the silicon carbide body, and wherein the shielding region and the drift structure form a pn junction.

15. The silicon carbide device of claim 1 , further comprising a body region of a second conductivity type in contact with the first gate structure and the at least one source region, wherein the body region and the shielding region are disposed at different sidewalls of the stripe-shaped trench gate structure.

16. A silicon carbide device, comprising:
an asymmetric transistor that includes a first stripe-shaped trench gate structure extending from a first surface into a silicon carbide body, the first gate structure having a gate length along a lateral first direction, a bottom surface and a first gate sidewall of the first gate structure being connected via a first bottom edge of the gate structure;
a source region of a first conductivity type in contact with the first gate sidewall of the first gate structure;
a second stripe-shaped trench gate structure extending from the first surface into the silicon carbide body, the second gate structure having a gate length along a lateral first direction, wherein a bottom surface, a first gate sidewall, and a second gate sidewall of the second gate structure are connected via a first bottom edge and a second bottom edge, respectively, of the gate structure; and
a shielding region of a second conductivity type in contact with the first bottom edge and the second bottom edge of the second gate structure across at least 20% of the gate length of the second gate structure, the shielding region also adjoining the source region,
wherein no source regions of the first conductivity type are in contact with a second gate sidewall of the gate structure.

17. The silicon carbide device of claim 16 , wherein the shielding region is in contact with the first bottom edge of the second gate structure across the gate length.

18. The silicon carbide device of claim 16 , wherein the source region extends along the gate length of the first gate structure.

19. The silicon carbide device of claim 16 , wherein both the source region and the shielding region are electrically connected to a source potential.

20. The silicon carbide device of claim 16 , further comprising a body region of a second conductivity type in contact with the first gate structure and the at least one source region, wherein the body region and the shielding region are disposed at different sidewalls of the stripe-shaped trench gate structure.

21. A silicon carbide device, comprising:
a stripe-shaped trench gate structure extending from a first surface into a silicon carbide body, the gate structure having a gate length along a lateral first direction, a bottom surface and a first gate sidewall of the gate structure being connected via a first bottom edge of the gate structure;
at least one source region of a first conductivity type in contact with the first gate sidewall; and
a shielding region of a second conductivity type in contact with the first bottom edge of the gate structure across at least 20% of the gate length;
wherein the shielding region comprises a top shielding portion and a deep shielding portion, wherein the to

Assignees

• Infineon Technologies Ag

Inventors

• Leendertz Caspar
• Basler Thomas
• Ellinghaus Paul
• Elpelt Rudolf
• Hell Michael
• Konrath Jens Peter
• Niu Shiqin
• Peters Dethard
• Schraml Konrad
• Zippelius Bernd Leonhard

Classifications

• H01L29/7813

  Electricity · mapped topic

• H01L29/1095

  Electricity · mapped topic

• H01L29/1608 Primary

  Electricity · mapped topic

• H01L29/4236

  Electricity · mapped topic

• H10D64/513

  within recesses in the substrate, e.g. trench gates, groove gates or buried gates · CPC title