Transistor having at least one transistor cell with a field electrode

• US 10,707,342 B2
• Filed: 03/01/2019
• Issued: 07/07/2020
• Est. Priority Date: 12/30/2015
• Status: Active Grant

• Current Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Original Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Inventors: Zundel, Markus, Hirler, Franz
• Primary Examiner(s): Nguyen, Khiem D
• Application Number:
  US16/290,204
• Publication Number:
  US 20190198661A1
• Time in Patent Office: 494 Days
• CPC Class Codes: H01L 23/5226 Via connections in a multilevel interconnection structure
• CPC Class Codes: H01L 23/53257 the principal metal being a refractory metal
• CPC Class Codes: H01L 23/53266 Additional layers associated with refractory-metal layers, e.g. adhesion, barrier, cladding layers
• CPC Class Codes: H01L 29/08 with semiconductor regions connected to an electrode carrying current to be rectified, amplified or switched and such electrode being part of a semiconductor device which comprises three or more electrodes
• CPC Class Codes: H01L 29/1095 Body region, i.e. base region, of DMOS transistors or IGBTs cell layout H01L29/0696
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/41741 for vertical or pseudo-vertical devices
• CPC Class Codes: H01L 29/41766 with at least part of the source or drain electrode having contact below the semiconductor surface, e.g. the source or drain electrode formed at least partially in a groove or with inclusions of conductor inside the semiconductor H01L29/41733 - H01L29/41758 take precedence
• CPC Class Codes: H01L 29/66727 with a step of recessing the source electrode
• CPC Class Codes: H01L 29/66734 with a step of recessing the gate electrode, e.g. to form a trench gate electrode
• CPC Class Codes: H01L 29/7811 with an edge termination structure guard regions per se H01L29/0619; field plates per se H01L29/402
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236

Abstract

Disclosed is a transistor device and a method for producing thereof. The transistor device includes at least one transistor cell, wherein the at least one transistor cell includes: a source region, a body region and a drift region in a semiconductor body; a gate electrode dielectrically insulated from the body region by a gate dielectric; a field electrode dielectrically insulated from the drift region by a field electrode dielectric; and a contact plug extending from a first surface of the semiconductor body to the field electrode and adjoining the source region and the body region.

Claims

1. A transistor device comprising at least one transistor cell, wherein the at least one transistor cell comprises:

a source region, a body region and a drift region in a semiconductor body;

a gate electrode dielectrically insulated from the body region by a gate dielectric;

a field electrode dielectrically insulated from the drift region by a field electrode dielectric; and

a contact plug arranged between a first surface of the semiconductor body and the field electrode and adjoining the source region and the body region,

wherein the field electrode and the field electrode dielectric are disposed in a field electrode trench that vertically extends into the semiconductor body, and

wherein upper surfaces of the field electrode and the field electrode dielectric are laterally covered by a portion of the semiconductor body that is arranged between the field electrode trench and the first surface of the semiconductor body,

wherein the portion of the semiconductor body that is arranged between the field electrode trench and the first surface comprises the body region, and wherein the body region directly contacts the upper surfaces of the field electrode and the field electrode dielectric.

2. The transistor device of claim 1, wherein the body region comprises a contact region that is more highly doped than a remainder of the body region and adjoins the contact plug.

3. The transistor device of claim 1, wherein the gate electrode and the field electrode overlap in a vertical direction of the semiconductor body.

4. The transistor device of claim 3, wherein a shortest distance between the field electrode dielectric and the gate dielectric in a lateral direction of the semiconductor body is smaller than 150 nanometers.

5. The transistor device of claim 1, wherein the gate electrode and the field electrode do not overlap in a vertical direction of the semiconductor body.

6. The transistor device of claim 5, wherein at least the gate dielectric overlaps the field electrode dielectric in a lateral direction of the semiconductor body.

7. The transistor device of claim 1, wherein the transistor device comprises a plurality of transistor cells, wherein the source region of each cell is connected to a common source node, and wherein the gate electrode of each transistor cell is connected to a common gate node.

8. The transistor device of claim 1, wherein the field electrode and the field electrode dielectric are arranged in a needle shaped trench.

9. The transistor device of claim 1, wherein the contact plug comprises an electrically conducting barrier layer on the field electrode and the semiconductor body, and an electrically conducting layer on the electrically conducting barrier layer.

10. The transistor device of claim 9, wherein the electrically conducting barrier layer comprises titanium and/or titanium nitride, and wherein the electrically conducting layer on the electrically conducting barrier layer comprises tungsten.

11. The transistor device of claim 1, wherein the gate electrode is disposed in a first trench formed in a semiconductor layer, and wherein the contact plug is disposed in a second trench formed in the semiconductor layer.

12. The transistor device of claim 11, wherein the first trench overlaps the field electrode dielectric in a lateral direction of the semiconductor body.

13. The transistor device of claim 1, wherein the upper surfaces of the field electrode and the field electrode dielectric are coplanar with one another.

14. A transistor device comprising at least one transistor cell, wherein the at least one transistor cell comprises:

a source region, a body region and a drift region in a semiconductor body;

a gate electrode dielectrically insulated from the body region by a gate dielectric; and

a field electrode dielectrically insulated from the drift region by a field electrode dielectric,

wherein in a lateral direction of the semiconductor body a shortest distance between the field electrode dielectric and the gate dielectric is smaller than 150 nanometers,

wherein the field electrode and the field electrode dielectric are disposed in a field electrode trench that vertically extends into the semiconductor body, and

wherein upper surfaces of the field electrode and the field electrode dielectric are laterally covered by a portion of the semiconductor body that is arranged between the field electrode trench and a first surface of the semiconductor body,

wherein the portion of the semiconductor body that is arranged between the field electrode trench and the first surface comprises the body region, and wherein the body region directly contacts the upper surfaces of the field electrode and the field electrode dielectric.

15. The transistor device of claim 14, wherein the gate dielectric overlaps the field electrode dielectric in the lateral direction.

16. The transistor device of claim 14, further comprising a contact plug arranged between the first surface of the semiconductor body and the field electrode and adjoining the source region and the body region.

17. The transistor device of claim 16, wherein the body region comprises a contact region that is more highly doped than a remainder of the body region and adjoins the contact plug.

18. The transistor device of claim 16, wherein the contact plug comprises an electrically conducting barrier layer on the field electrode and the semiconductor body, and an electrically conducting layer on the electrically conducting barrier layer.

19. The transistor device of claim 18, wherein the electrically conducting barrier layer comprises titanium and/or titanium nitride, and wherein the electrically conducting layer on the electrically conducting barrier layer comprises tungsten.

20. The transistor device of claim 14, wherein the transistor device comprises a plurality of transistor cells, wherein the source region of each cell is connected to a common source node, and wherein the gate electrode of each transistor cell is connected to a common gate node.

21. The transistor device of claim 14, wherein the field electrode and the field electrode dielectric are arranged in a needle shaped trench.

22. The transistor device of claim 14, wherein the upper surfaces of the field electrode and the field electrode dielectric are coplanar with one another.