High-voltage vertical transistor with edge termination structure

• US 20050167749A1
• Filed: 02/03/2005
• Published: 08/04/2005
• Est. Priority Date: 09/07/2001
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Disney, Donald Ray
• Granted Patent: US 7,786,533 B2
• Time in Patent Office: Days
• US Class Current: 257/341
• CPC Class Codes: H01L 29/0653 adjoining the input or output region of a field-effect device, e.g. the source or drain region
• CPC Class Codes: H01L 29/0696 of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
• CPC Class Codes: H01L 29/402 Field plates
• 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 29/42368 the thickness being non-uniform
• CPC Class Codes: H01L 29/7802 Vertical DMOS transistors, i.e. VDMOS transistors
• 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
• CPC Class Codes: H01L 29/7824 with a substrate comprising an insulating layer, e.g. SOI-LDMOS transistors
• CPC Class Codes: H01L 29/7828 without inversion channel, e.g. vertical ACCUFETs, normally-on vertical MISFETs

Abstract

A high-voltage transistor includes a drain, a source, and one or more drift regions extending from the drain toward the source. A field plate member laterally surrounds the drift regions and is insulated from the drift regions by a dielectric layer. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Claims

1. A high-voltage transistor comprising:

a drain of a first conductivity type;

a source of the first conductivity type;

a plurality of drift regions of the first conductivity type extending in a vertical direction from the drain toward the source, adjacent ones of the drift regions being separated in a first lateral direction by a dielectric layer, each of the drift regions terminating in a second lateral direction in a fingertip area; and

a field plate member disposed within the dielectric layer that surrounds each of the drift regions in the first and second lateral directions.

2. The high-voltage transistor according to claim 1 wherein the fingertip area has a rounded shape.

3. The high-voltage transistor according to claim 1 wherein an inner region of the dielectric layer separates the drift regions from the field plate member and an outer region of the dielectric layer separates the field plate member from a scribe area of the high-voltage transistor.

4. The high-voltage transistor according to claim 3 wherein the inner and outer regions have substantially the same width.

5. The high-voltage transistor according to claim 1 wherein the high-voltage transistor is fabricated on a semiconductor substrate having a planar bottom surface, the vertical direction being oriented perpendicular to the planar bottom surface and the first and second lateral directions being oriented parallel to the planar bottom surface.

6. The high-voltage transistor according to claim 1 wherein each of the drift regions have a length oriented in the vertical direction and a width oriented in a first lateral direction, the length being more than five times the width.

7. The high-voltage transistor according to claim 1 wherein the first conductivity type comprises n-type.

8. The high-voltage transistor according to claim 1 wherein the field plate member extends in the vertical direction, oriented substantially parallel to the drift regions.

9. The high-voltage transistor according to claim 1 further comprising a body region of a second conductivity type, the body region separating the source from each drift region.

10. A high-voltage transistor comprising:

a drain of a first conductivity type;

a source of the first conductivity type;

a first trench filled with a dielectric material;

a first conductive field plate member disposed in the dielectric material;

a drift region of the first conductivity type that laterally surrounds the first trench and extends in a vertical direction from the drain toward the source, the dielectric material insulating the first conductive field plate member from the drift region;

a second trench that laterally surrounds the drift region, the second trench being filled with the dielectric material;

a second conductive field plate member disposed in the dielectric material of the second trench, the dielectric material of the second trench insulating the second conductive field plate member from the drift region.

11. The high-voltage transistor according to claim 10 wherein the drift region has a ring shape in first and second lateral directions orthogonal to the vertical direction.

12. The high-voltage transistor according to claim 11 wherein the ring shape is elongated in the first lateral direction.

13. The high-voltage transistor according to claim 11 wherein the ring shape is substantially rectilinear.

14. The high-voltage transistor according to claim 10 wherein an inner region of the dielectric material of the second trench separates the drift region from the second conductive field plate member, an outer region of the dielectric material separating the second conductive field plate member from a scribe area of the high-voltage transistor.

15. The high-voltage transistor according to claim 14 wherein the inner and outer regions have substantially the same width.

16. The high-voltage transistor according to claim 10 wherein the second conductive field plate member comprises a ring shape in first and second lateral directions orthogonal to the vertical direction.

17. The high-voltage transistor according to claim 16 wherein the first conductive field plate member terminates in a first lateral direction in a fingertip area having a rounded shape.

18. The high-voltage transistor according to claim 10 wherein the first conductive field plate member laterally encircles a portion of the drain.

19. The high-voltage transistor according to claim 10 wherein the high-voltage transistor is fabricated on a semiconductor substrate having a planar bottom surface, the vertical direction being oriented perpendicular to the planar bottom surface and the first and second lateral directions being oriented parallel to the planar bottom surface.

20. The high-voltage transistor according to claim 10 wherein each of the drift regions have a length oriented in the vertical direction and a width oriented in a second lateral direction, the length being more than five times the width.

21. The high-voltage transistor according to claim 10 wherein the first conductivity type comprises n-type.

22. The high-voltage transistor according to claim 10 further comprising a body region of a second conductivity type, the body region separating the source from the drift region.

23. A high-voltage transistor comprising:

a substrate;

a plurality of trenches in the substrate which includes an outer trench that laterally encircles a plurality of inner trenches, the outer trench and inner trenches defining a mesa region that extends in a vertical direction from a top to a bottom of the trenches in the substrate, the mesa region comprising a plurality of drift regions that extend in a first lateral direction, with each end of the drift regions being connected together by a portion of the mesa region that extends in a second lateral direction;

a plurality of first field plate members, each being disposed in a corresponding one of the inner trenches and insulated from the mesa region by a dielectric material;

a second field plate member disposed in the outer trench, the second field plate member being insulated from the mesa region by a second dielectric material.

24. The high-voltage transistor according to claim 23 wherein the second field plate member has a ring shape in first and second lateral directions orthogonal to the vertical direction.

25. The high-voltage transistor according to claim 23 wherein the first and second dielectric materials comprise an oxide.

26. The high-voltage transistor according to claim 23 wherein an inner region of the second dielectric material of the outer trench separates the mesa region from the second field plate member, an outer region of the second dielectric material of the outer trench separating the second field plate member from a scribe area of the high-voltage transistor.

27. The high-voltage transistor according to claim 26 wherein the inner and outer regions have substantially the same width.

28. The high-voltage transistor according to claim 23 wherein the substrate has a planar bottom surface, the vertical direction being oriented perpendicular to the planar bottom surface.

29. A high-voltage transistor comprising:

a drain of a first conductivity type;

a source of the first conductivity type;

a drift region of the first conductivity type extending in a vertical direction from the drain toward the source; and

a field plate member that laterally encircles the drift region, the field plate member being insulated from the drift region by a dielectric layer.

30. The high-voltage transistor according to claim 29 wherein the drift region extends in a lateral direction, terminating at each end in a rounded fingertip area.

31. The high-voltage transistor according to claim 29 wherein an inner region of the dielectric layer separates the drift region from the field plate member and an outer region of the dielectric layer separates the field plate member from a scribe area of the high-voltage transistor.

32. The high-voltage transistor according to claim 31 wherein the inner and outer regions have substantially the same width.

33. The high-voltage transistor according to claim 30 wherein the high-voltage transistor is fabricated on a semiconductor substrate having a planar bottom surface, the vertical direction being oriented perpendicular to the planar bottom surface and the lateral direction being oriented parallel to the planar bottom surface.

34. The high-voltage transistor according to claim 29 wherein the first conductivity type comprises n-type.

35. The high-voltage transistor according to claim 29 wherein the field plate member extends in the vertical direction, oriented substantially parallel to the drift region.

36. The high-voltage transistor according to claim 29 further comprising a body region of a second conductivity type, the body region separating the source from the drift region.

37. A high-voltage transistor comprising:

a substrate;

an outer trench in the substrate;

one or more inner trenches laterally encircled by the outer trenches, the outer trench and the one or more inner trenches defining a mesa region that comprises one or more drift regions;

one or more inner field plate members, each being disposed in a corresponding one of the one or more inner trenches and insulated from the mesa region by a dielectric material;

an outer field plate member disposed in the outer trench, the outer field plate member being insulated from the mesa region by the dielectric material.

38. The high-voltage transistor according to claim 37 wherein the outer field plate member has a ring shape.

39. The high-voltage transistor according to claim 37 wherein the first and second dielectric materials comprise an oxide.

40. The high-voltage transistor according to claim 37 wherein the outer trench separates the outer field plate member from a scribe area of the high-voltage transistor.

41. The high-voltage transistor according to claim 37 wherein the one or more drift regions terminate at each lateral end in a rounded fingertip area.