Power MOSFET with seperate gate and field plate trenches

Patent metadata

Field	Value
Publication number	US-9680004-B2
Application number	US-201514793779-A
Country	US
Kind code	B2
Filing date	Jul 8, 2015
Priority date	Jul 14, 2014
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

A power MOSFET includes a gate electrode in a gate trench in a main surface of a semiconductor substrate, the gate trench extending parallel to the main surface. The power MOSFET further includes a field electrode in a field plate trench in the main surface. The field plate trench has an extension length in a first direction which is less than double and more than half of an extension length of the field plate trench in a second direction perpendicular to the first direction, the first and the second directions being parallel to the main surface. The gate electrode includes a gate electrode material which comprises a metal.

First claim

What is claimed is:

1. A power metal oxide semiconductor field effect transistor, comprising:
a gate electrode in a gate trench in a main surface of a semiconductor substrate, the gate trench extending parallel to the main surface; and
a field electrode in a field plate trench in the main surface, the field plate trench having an extension length in a first direction which is less than double and more than half of an extension length of the field plate trench in a second direction perpendicular to the first direction, the first and the second directions being parallel to the main surface,
wherein the gate electrode comprises a gate electrode material, the gate electrode material comprising a metal.

2. The power metal oxide semiconductor field effect transistor of claim 1 , wherein the gate electrode material comprises a combination of a first and a second metal layer, the first metal layer being adjacent to a gate dielectric.

3. The power metal oxide semiconductor field effect transistor of claim 2 , wherein the first metal layer is a metal nitride.

4. The power metal oxide semiconductor field effect transistor of claim 2 , wherein the second metal layer is tungsten or a silicide containing polysilicon layer.

5. The power metal oxide semiconductor field effect transistor of claim 1 , wherein a width of the gate trench measured perpendicularly to the first direction is less than 500 nm.

6. The power metal oxide semiconductor field effect transistor of claim 1 , further comprising a source region adjacent to the main surface and a drain region adjacent to a back side surface opposite the main surface, and a body region adjacent to the gate electrode.

7. The power metal oxide semiconductor field effect transistor of claim 6 , further comprising a drift zone between the body region and the drain region.

8. The power metal oxide semiconductor field effect transistor of claim 1 , further comprising a plurality of field plate trenches arranged along the first direction between two adjacent gate trenches.

9. The power metal oxide semiconductor field effect transistor of claim 1 , further comprising a plurality of transistor cells configured to be controlled by the gate electrode.

10. The power metal oxide semiconductor field effect transistor of claim 1 , wherein a width of the gate trench measured perpendicularly to the first direction is smaller than a width of the field plate trench measured perpendicularly to the first direction.

11. The power metal oxide semiconductor field effect transistor of claim 1 , further comprising a gate dielectric having a thickness of 20 to 100 nm.

12. A synchronous rectification device comprising the power metal oxide semiconductor field effect transistor of claim 1 .

13. A power supply comprising the synchronous rectification device of claim 12 .

14. A power metal oxide semiconductor field effect transistor, comprising:
a gate electrode in a gate trench in a main surface of a semiconductor substrate, the gate trench extending parallel to the main surface; and
a field electrode in a field plate trench in the main surface, the field plate trench having an extension length parallel to the main surface which is less than a depth of the field plate trench,
wherein the gate electrode comprises a gate electrode material, the gate electrode material comprising a metal,
wherein the field plate trench is separate from the gate trench.

15. The power metal oxide semiconductor field effect transistor of claim 14 , wherein the extension length is less than 0.2 times the depth of the field plate trench.

Assignees

• Infineon Technologies Austria Ag

Inventors

• Laforet David
• Blank Oliver
• Hutzler Michael
• Ouvrard Cedric
• Siemieniec Ralf
• Yip Li Juin

Classifications

• H01L29/404

  Electricity · mapped topic

• H01L29/4966

  Electricity · mapped topic

• H01L29/4238

  Electricity · mapped topic

• H01L29/7813 Primary

  Electricity · mapped topic

• H01L29/407

  Electricity · mapped topic