Multiple semiconductor device trenches per cell pitch

• US 9,252,263 B1
• Filed: 07/31/2014
• Issued: 02/02/2016
• Est. Priority Date: 07/31/2014
• Status: Expired due to Fees

• Current Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Original Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Inventors: Vielemeyer, Martin, Hutzler, Michael
• Primary Examiner(s): Potter, Roy
• Assistant Examiner(s): Patton, Paul
• Application Number:
  US14/447,864
• Publication Number:
  US 20160035882A1
• Time in Patent Office: 551 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 29/0696 of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• 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 29/4238 characterised by the surface lay-out
• CPC Class Codes: H01L 29/7803 structurally associated with at least one other device assemblies H01L25/00; integrated circuits H01L27/00
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236

Abstract

A semiconductor device includes a plurality of field plate trenches formed in a semiconductor substrate, a plurality of gate trenches formed in the semiconductor substrate and spaced apart from the field plate trenches, and a plurality of device cells having a cell pitch defined by a distance from one side of a field plate trench to the same side of an adjacent field plate trench. Each device cell includes a first doped region of a first conductivity type and a second doped region of a second conductivity type adjacent the first doped region in a part of the semiconductor substrate disposed between the adjacent field plate trenches that define the cell pitch. At least some of the device cells have more than one gate trench per cell pitch.

Claims

1. A semiconductor device, comprising:

a plurality of field plate trenches formed in a semiconductor substrate;

a plurality of gate trenches formed in the semiconductor substrate and spaced apart from the field plate trenches; and

a plurality of device cells having a cell pitch defined by a distance from one side of a field plate trench to the same side of an adjacent field plate trench, each device cell comprising a first doped region of a first conductivity type and a second doped region of a second conductivity type adjacent the first doped region in a part of the semiconductor substrate disposed between the adjacent field plate trenches that define the cell pitch,

wherein at least some of the device cells have more than one gate trench per cell pitch,

wherein at least some of the device cells that have more than one gate trench per cell pitch include only a single type of gate trench that comprises a gate conductor disposed in a gate trench.

2. The semiconductor device of claim 1, wherein at least some of the device cells that have more than one gate trench per cell pitch include a first type of gate trench and a second type of gate trench, wherein the first type of gate trench comprises a gate conductor disposed in a gate trench and electrically insulated from the first and second doped regions of the device cell, and wherein the second type of gate trench comprises a gate conductor disposed in a gate trench and electrically connected to the first and second doped regions of the device cell.

3. The semiconductor device of claim 2, wherein the gate trenches of the first type have a different geometry than the gate trenches of the second type within the same device cell.

4. The semiconductor device of claim 1, wherein the gate conductor of each device cell that includes only a single type of gate trench is electrically insulated from the first and second doped regions of the device cell.

5. The semiconductor device of claim 1, wherein the gate conductor of each device cell that includes only a single type of gate trench is electrically connected to the first and second doped regions of the device cell.

6. The semiconductor device of claim 1, wherein all of the device cells that have more than one gate trench per cell pitch include only a single type of gate trench that comprises a gate conductor disposed in a gate trench and electrically connected to the first and second doped regions of the device cell.

7. The semiconductor device of claim 1, wherein the field plate trenches extend in strips along a direction parallel to a first main surface of the semiconductor substrate.

8. The semiconductor device of claim 7, wherein the first doped region of the device cells is a transistor source region, wherein the second doped region of the device cells is a transistor body region, and wherein the device cells that have more than one gate trench per cell pitch further comprise a contact disposed between the gate trenches for electrically contacting the transistor body region.

9. The semiconductor device of claim 1, wherein the field plate trenches have an extension in every direction in parallel to a first main surface of the semiconductor substrate, which is smaller than a maximum extension in a direction perpendicular to the first main surface.

10. The semiconductor device of claim 9, wherein the first doped region of the device cells is a transistor source region, wherein the second doped region of the device cells is a transistor body region, and wherein the body region of the device cells that have more than one gate trench per cell pitch is electrically contacted within the device cells only through a field plate in the field plate trenches.

11. The semiconductor device of claim 9, wherein at least two of the gate trenches of the device cells that have more than one gate trench per cell pitch intersect within the same device cell.

12. The semiconductor device of claim 11, wherein a portion of the second doped region is segmented into islands by the intersecting gate trenches, and wherein the device cells that have more than one gate trench per cell pitch further comprise a contact for electrically contacting the islands of the second doped region.

13. The semiconductor device of claim 9, wherein the gate trenches of the device cells that have more than one gate trench per cell pitch are non-intersecting within the same device cell so that the second doped region extends continuously within each device cell to the end of the device cell without interruption by the gate trenches.

14. The semiconductor device of claim 13, wherein the second doped region of the device cells that have more than one gate trench per cell pitch is electrically contacted within the device cells only through a field plate in the field plate trenches.

15. The semiconductor device of claim 9, wherein at least some of the device cells that have more than one gate trench per cell pitch include a first type of gate trench and a second type of gate trench, wherein the first type of gate trench comprises a gate conductor disposed in a gate trench and electrically insulated from the first and second doped regions of the device cell, and wherein the second type of gate trench comprises a gate conductor disposed in a gate trench and electrically connected to the first and second doped regions of the device cell.

16. The semiconductor device of claim 15, wherein the gate trenches of the first type have a different geometry than the gate trenches of the second type within the same device cell.

17. The semiconductor device of claim 9, wherein at least some of the device cells that have more than one gate trench per cell pitch include only a single type of gate trench that comprises a gate conductor disposed in a gate trench and electrically insulated from the first and second doped regions of the device cell.

18. The semiconductor device of claim 9, wherein at least some of the device cells that have more than one gate trench per cell pitch include only a single type of gate trench that comprises a gate conductor disposed in a gate trench and electrically connected to the first and second doped regions of the device cell.

19. The semiconductor device of claim 9, wherein all of the device cells that have more than one gate trench per cell pitch include only a single type of gate trench that comprises a gate conductor disposed in a gate trench and electrically connected to the first and second doped regions of the device cell.

20. The semiconductor device of claim 9, wherein a first type of the gate trenches comprises a gate conductor disposed in a gate trench and electrically insulated from the first and second doped regions of the device cell, wherein a second type of the gate trenches comprises a gate conductor disposed in a gate trench and electrically connected to the first and second doped regions of the device cell, wherein each gate trench of the second type forms an inner ring around one of the field plate trenches, and wherein each gate trench of the first type forms an outer ring around one of the gate trenches of the second type so that an intermediary ring of the second doped region is interposed between the inner and outer trench rings.

21. The semiconductor device of claim 20, further comprising a contact for electrically contacting the intermediary ring of the second doped region.

22. A semiconductor device, comprising:

a plurality of field plate trenches formed in a semiconductor substrate;

a plurality of gate trenches formed in the semiconductor substrate and spaced apart from the field plate trenches; and

a plurality of device cells having a cell pitch defined by a distance from one side of a field plate trench to the same side of an adjacent field plate trench, each device cell comprising a first doped region of a first conductivity type and a second doped region of a second conductivity type adjacent the first doped region in a part of the semiconductor substrate disposed between the adjacent field plate trenches that define the cell pitch,

wherein at least some of the device cells have more than one gate trench per cell pitch,

wherein the field plate trenches have an extension in every direction in parallel to a first main surface of the semiconductor substrate, which is smaller than a maximum extension in a direction perpendicular to the first main surface,

wherein the first doped region of the device cells is a transistor source region, wherein the second doped region of the device cells is a transistor body region, and wherein the body region of the device cells that have more than one gate trench per cell pitch is electrically contacted within the device cells only through a field plate in the field plate trenches.

23. A semiconductor device, comprising:

a plurality of field plate trenches formed in a semiconductor substrate;

a plurality of gate trenches formed in the semiconductor substrate and spaced apart from the field plate trenches; and

a plurality of device cells having a cell pitch defined by a distance from one side of a field plate trench to the same side of an adjacent field plate trench, each device cell comprising a first doped region of a first conductivity type and a second doped region of a second conductivity type adjacent the first doped region in a part of the semiconductor substrate disposed between the adjacent field plate trenches that define the cell pitch,

wherein at least some of the device cells have more than one gate trench per cell pitch,

wherein the field plate trenches have an extension in every direction in parallel to a first main surface of the semiconductor substrate, which is smaller than a maximum extension in a direction perpendicular to the first main surface,

wherein at least two of the gate trenches of the device cells that have more than one gate trench per cell pitch intersect within the same device cell.

24. The semiconductor device of claim 23, wherein a portion of the second doped region is segmented into islands by the intersecting gate trenches, and wherein the device cells that have more than one gate trench per cell pitch further comprise a contact for electrically contacting the islands of the second doped region.

25. A semiconductor device, comprising:

a plurality of field plate trenches formed in a semiconductor substrate;

a plurality of gate trenches formed in the semiconductor substrate and spaced apart from the field plate trenches; and

a plurality of device cells having a cell pitch defined by a distance from one side of a field plate trench to the same side of an adjacent field plate trench, each device cell comprising a first doped region of a first conductivity type and a second doped region of a second conductivity type adjacent the first doped region in a part of the semiconductor substrate disposed between the adjacent field plate trenches that define the cell pitch,

wherein at least some of the device cells have more than one gate trench per cell pitch,

wherein the field plate trenches have an extension in every direction in parallel to a first main surface of the semiconductor substrate, which is smaller than a maximum extension in a direction perpendicular to the first main surface,

wherein the gate trenches of the device cells that have more than one gate trench per cell pitch are non-intersecting within the same device cell so that the second doped region extends continuously within each device cell to the end of the device cell without interruption by the gate trenches,

wherein the second doped region of the device cells that have more than one gate trench per cell pitch is electrically contacted within the device cells only through a field plate in the field plate trenches.

26. A semiconductor device, comprising:

a plurality of field plate trenches formed in a semiconductor substrate;

a plurality of gate trenches formed in the semiconductor substrate and spaced apart from the field plate trenches; and

a plurality of device cells having a cell pitch defined by a distance from one side of a field plate trench to the same side of an adjacent field plate trench, each device cell comprising a first doped region of a first conductivity type and a second doped region of a second conductivity type adjacent the first doped region in a part of the semiconductor substrate disposed between the adjacent field plate trenches that define the cell pitch,

wherein at least some of the device cells have more than one gate trench per cell pitch,

wherein the field plate trenches have an extension in every direction in parallel to a first main surface of the semiconductor substrate, which is smaller than a maximum extension in a direction perpendicular to the first main surface,

wherein at least some of the device cells that have more than one gate trench per cell pitch include a first type of gate trench and a second type of gate trench, wherein the first type of gate trench comprises a gate conductor disposed in a gate trench and electrically insulated from the first and second doped regions of the device cell, and wherein the second type of gate trench comprises a gate conductor disposed in a gate trench and electrically connected to the first and second doped regions of the device cell,

wherein the gate trenches of the first type have a different geometry than the gate trenches of the second type within the same device cell.