Semiconductor device with stripe-shaped trench gate structures and gate connector structure

• US 9,530,850 B2
• Filed: 12/21/2015
• Issued: 12/27/2016
• Est. Priority Date: 12/22/2014
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Aichinger, Thomas, Bergner, Wolfgang
• Primary Examiner(s): YEUNG LOPEZ, FEIFEI
• Application Number:
  US14/976,566
• Publication Number:
  US 20160181408A1
• Time in Patent Office: 372 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 21/02236 group IV semiconductor
• CPC Class Codes: H01L 21/02255 formation by thermal treatment H01L21/02252 takes precedence; after treatment of an insulating film H01L21/3105 and subgroups
• CPC Class Codes: H01L 21/049 Conductor-insulator-semiconductor electrodes, e.g. MIS contacts
• CPC Class Codes: H01L 21/823462 with a particular manufacturing method of the gate insulating layers, e.g. different gate insulating layer thicknesses, particular gate insulator materials or particular gate insulator implants
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 29/0696 of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
• CPC Class Codes: H01L 29/1608 Silicon carbide
• CPC Class Codes: H01L 29/4236 within a trench, e.g. trench gate electrode, groove gate electrode
• CPC Class Codes: H01L 29/42368 the thickness being non-uniform
• CPC Class Codes: H01L 29/4238 characterised by the surface lay-out
• CPC Class Codes: H01L 29/7397 and a gate structure lying on a slanted or vertical surface or formed in a groove, e.g. trench gate IGBT
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/13055 Insulated gate bipolar transistor [IGBT]
• CPC Class Codes: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]

Abstract

A semiconductor device includes a transistor cell with a stripe-shaped trench gate structure that extends from a first surface into a semiconductor body. A gate connector structure at a distance to the first surface is electrically connected to a gate electrode in the trench gate structure. A gate dielectric separates the gate electrode from the semiconductor body. First sections of the gate dielectric outside a vertical projection of the gate connector structure are thinner than second sections within the vertical projection of the gate connector structure.

Claims

1. A semiconductor device, comprising:

a transistor cell that comprises a stripe-shaped trench gate structure extending from a first surface into a semiconductor body;

a gate connector structure at a distance to the first surface and at a distance to end sections of the trench gate structure, and electrically connected to a gate electrode in the trench gate structure; and

a gate dielectric separating the gate electrode from the semiconductor body, wherein first sections of the gate dielectric outside a vertical projection of the gate connector structure are thinner than second sections within the vertical projection of the gate connector structure.

2. The semiconductor device of claim 1, wherein

the gate connector structure includes a gate pad and a bond wire fixed to the gate pad.

3. The semiconductor device of claim 1, wherein

the gate connector structure includes a stripe-shaped gate finger crossing a plurality of gate trench structures and electrically connected to the gate electrodes in the gate trench structures.

4. The semiconductor device of claim 1, wherein

the gate dielectric comprises a further second section in a trench end section of the trench gate structure.

5. The semiconductor device of claim 1, wherein

the semiconductor body is based on silicon carbide.

6. The semiconductor device of claim 1, wherein

the first section comprises a first portion of a first sublayer and the second section comprises a second sublayer, which is absent in the first section, and a second portion of the first sublayer.

7. The semiconductor device of claim 1, wherein

a thickness of the second sections exceeds a thickness of the first sections by at least 20%.

8. A semiconductor device, comprising:

a transistor cell that comprises a stripe-shaped trench gate structure extending from a first surface into a semiconductor body, wherein the transistor cell includes an active section through which a load current flows in a vertical direction perpendicular to the first surface when the transistor cell is in an on-state and an idle section through which no load current flows in the vertical direction when the transistor cell is in the on-state;

wherein

a second section of a gate dielectric in the idle section includes at least one sublayer more than a first section of the gate dielectric in the active section.

9. The semiconductor device of claim 8, further comprising:

a gate connector structure electrically connected to a gate electrode in the trench gate structure and formed at a distance to the first surface, wherein at least a portion of the idle section is formed in a vertical projection of the gate connector structure.

10. The semiconductor device of claim 9, wherein

the gate connector structure includes a gate pad and a bond wire fixed to the gate pad.

11. The semiconductor device of claim 9, wherein

the gate connector structure includes a stripe-shaped gate finger crossing a plurality of gate trench structures.

12. The semiconductor device of claim 8, wherein

the semiconductor body is based on silicon carbide.

13. The semiconductor device of claim 8, wherein

one of the first and second dielectric layers is a semiconductor oxide layer formed by thermal oxidation of the semiconductor body.

14. The semiconductor device of claim 8, wherein

the first section comprises a first portion of a first sublayer and the second section comprises a second sublayer, which is absent in the first section, and a second portion of the first sublayer.

15. A semiconductor device, comprising:

a transistor cell that comprises a stripe-shaped trench gate structure extending from a first surface into a semiconductor body, wherein the transistor cell includes an active section through which a load current flows in a vertical direction perpendicular to the first surface when the transistor cell is in an on-state and an idle section through which no load current flows in the vertical direction when the transistor cell is in the on-state;

wherein

a second section of a gate dielectric in the idle section is thicker than a first section of the gate dielectric in the active section and separates a gate electrode in the trench structures from body zones.

16. The semiconductor device of claim 15, further comprising:

a gate connector structure electrically connected to the gate electrode in the trench gate structure and formed in a distance to the first surface, wherein at least a portion of the idle section is formed in a vertical projection of the gate connector structure.

17. The semiconductor device of claim 15, wherein

the gate connector structure includes a gate pad and a bond wire fixed to the gate pad.

18. The semiconductor device of claim 15, wherein

the gate connector structure includes a stripe-shaped gate finger crossing a plurality of gate trench structures.

19. The semiconductor device of claim 15, wherein

the second section of the gate dielectric in the idle section includes at least one layer more than the first section of the gate dielectric in the active section.

20. The semiconductor device of claim 15, wherein

the first section comprises a first portion of a first sublayer and the second section comprises a second sublayer, which is absent in the first section, and a second portion of the first sublayer.

21. The semiconductor device of claim 15, wherein

the semiconductor body is based on silicon carbide.