High-voltage lateral transistor with a multi-layered extended drain structure

• US 20030047792A1
• Filed: 04/30/2002
• Published: 03/13/2003
• Est. Priority Date: 09/07/2001
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Paul, Amit, Disney, Donald Ray
• Granted Patent: US 6,815,293 B2
• Time in Patent Office: Days
• US Class Current: 257/488
• 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 29/0886 Shape
• 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 29/4232 with insulated gate
• 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 29/7802 Vertical DMOS transistors, i.e. VDMOS transistors
• 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 29/7825 with trench gate electrode trench gate electrodes per se H01L29/4236
• CPC Class Codes: H01L 29/86 controllable only by variation of the electric current supplied, or only the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched
• CPC Class Codes: H01L 29/861 Diodes
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A high-voltage transistor with a low specific on-state resistance and that supports high voltage in the off-state includes one or more source regions disposed adjacent to a multi-layered extended drain structure which comprises extended drift regions separated from field plate members by one or more dielectric layers. The layered structure may be fabricated in a variety of orientations. A MOSFET structure may be incorporated into the device adjacent to the source region, or, alternatively, the MOSFET structure may be omitted to produce a high-voltage transistor structure having a stand-alone drift region. 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.

Claims

1. A high-voltage transistor fabricated on a substrate comprising:

a drain region of a first conductivity type;

a body region of a second conductivity type opposite to the first conductivity type;

a plurality of drift regions of the first conductivity type, each of the drift regions extending in a first direction from the drain region to the body region, adjacent ones of the drift regions being separated in a second direction substantially orthogonal to the first direction by a dielectric layer;

a field plate member disposed within the dielectric layer, the field plate member being insulated in the second direction from one of the plurality of drift regions by a portion of the dielectric layer, the portion of the dielectric layer having an insulation width that varies along the first direction, the insulation width being narrowest near the body region and widest near the drain region;

a source region of the first conductivity type, the source region being separated from the drift regions by the body region; and

an insulated gate member disposed adjacent to the body region.

2. The high-voltage transistor according to claim 1 wherein the second direction is oriented substantially perpendicular to a bottom surface of the substrate.

3. The high-voltage transistor according to claim 1 wherein the second direction is oriented substantially parallel to a bottom surface of the substrate.

4. The high-voltage transistor according to claim 1 further comprising an insulating layer that covers the substrate, the drift regions being disposed above the insulating layer.

5. The high-voltage transistor according to claim 4 wherein the substrate comprises a bottom field plate member.

6. The high-voltage transistor according to claim 1 further comprising:

a drain electrode electrically connected to the drain region;

a source electrode electrically connected to the source region.

7. The high-voltage transistor according to claim 1 wherein the first conductivity type is n-type and the second conductivity type is p-type.

8. The high-voltage transistor according to claim 6 wherein the drain region extends in a vertical direction from the insulating layer to the drain electrode.

9. The high-voltage transistor according to claim 1 wherein the source region is disposed above the body region.

10. The high-voltage transistor according to claim 9 further comprising a gate electrode electrically connected to the insulated gate member.

11. The high-voltage transistor according to claim 1 wherein the source region is disposed in the body region.

12. The high-voltage transistor according to claim 1 wherein a channel region is defined in the body region adjacent the insulated gate member between the source region and at least one of the drift regions, the channel region extending substantially parallel to the top surface of the substrate.

13. The high-voltage transistor according to claim 1 wherein the field plate member comprises polysilicon.

14. The high-voltage transistor according to claim 1 wherein the drift regions are substantially uniformly doped.

15. The high-voltage transistor according to claim 1 wherein each of the drift regions has a substantially uniform width in the second direction.

16. The high-voltage transistor according to claim 1 wherein the field plate member is electrically coupled to the source region.

17. The high-voltage transistor according to claim 1 wherein the field plate member is electrically coupled to the insulated gate member.

18. The high-voltage transistor according to claim 1 wherein the field plate member has a width that varies in a complementary manner with the insulation width.

26. The high-voltage transistor according to claim 16 wherein the at least one field plate member comprises polysilicon.

19. A high-voltage transistor comprising:

a drain region of a first conductivity type;

at least one source region of the first conductivity type;

a plurality of drift regions of the first conductivity type arranged in parallel and extending in a first direction from the drain region to the at least one source region, adjacent ones of the drift regions being separated in a second direction substantially orthogonal to the first direction by a dielectric layer;

at least one field plate member disposed within the dielectric layer, the at least one field plate member being insulated in the second direction from one of the plurality of drift regions by a portion of the dielectric layer, the portion of the dielectric layer having an insulation width that varies along the first direction, the insulation width being narrowest near the source region and widest near the drain region.

20. The high-voltage transistor according to claim 19 wherein the high-voltage transistor is fabricated on a substrate having a bottom surface, the second direction being oriented substantially perpendicular to the bottom surface of the substrate.

21. The high-voltage transistor according to claim 19 wherein the high-voltage transistor is fabricated on a substrate having a bottom surface, the second direction being oriented substantially parallel to a bottom surface of the substrate.

22. The high-voltage transistor according to claim 19 wherein the high-voltage transistor is fabricated on a substrate, and further comprising an insulating layer that covers the substrate, the drift regions being disposed above the insulating layer.

23. The high-voltage transistor according to claim 19 wherein the high-voltage transistor is fabricated on a substrate, which comprises a bottom field plate member.

24. The high-voltage transistor according to claim 19 further comprising:

a drain electrode electrically connected to the drain region;

a source electrode electrically connected to the at least one source region.

25. The high-voltage transistor according to claim 19 wherein the first conductivity type is n-type and the second conductivity type is p-type.

27. The high-voltage transistor according to claim 19 wherein the at least one field plate member has a width in the second direction that varies in a complementary manner with respect to the insulation width.

28. The high-voltage transistor according to claim 19 wherein the drift regions are substantially uniformly doped.

29. The high-voltage transistor according to claim 19 wherein each of the drift regions has a substantially uniform width in the second direction.

30. The high-voltage transistor according to claim 19 wherein the drift regions comprise an epitaxial layer.

31. The high-voltage transistor according to claim 19 wherein the at least one field plate member is electrically coupled to the at least one source region.

32. The high-voltage transistor according to claim 19 further comprising an insulated gate member.

33. A high-voltage transistor fabricated on a substrate, comprising:

a drain region of a first conductivity type;

a source region of the first conductivity type;

a drift region of the first conductivity type extending from the drain region in a first direction substantially parallel to a bottom surface of the substrate;

a dielectric layer that adjoins the drift region, the dielectric layer having an insulation width in a second direction substantially orthogonal to the first direction;

a field plate member insulated in the second direction from the drift region by the dielectric layer; and

wherein the insulation width varies along the first direction, the insulation width being narrowest near the source region and widest near the drain region.

34. The high-voltage transistor according to claim 33 wherein the insulation width varies in a linear manner.

35. The high-voltage transistor according to claim 33 further comprising:

a source electrode electrically connected to the source region; and

a drain electrode electrically connected to the drain region.

36. The high-voltage transistor according to claim 33 wherein the drift region has a width in the second direction, the width of the drift region being substantially uniform along the first direction.

37. The high-voltage transistor according to claim 33 wherein the first conductivity type comprises n-type and the second conductivity type comprises p-type.

38. The high-voltage transistor according to claim 33 wherein the second direction is substantially parallel to a bottom surface of the substrate.

39. The high-voltage transistor according to claim 33 wherein the second direction is substantially orthogonal to a bottom surface of the substrate.

40. The high-voltage transistor according to claim 33 further comprising a body region of a second conductivity type opposite to the first conductivity type, the drift region extending from the drain region to the body region.

45. The high-voltage transistor according to claim 33 wherein the second direction that is substantially parallel to a bottom surface of the substrate.

41. A high-voltage transistor fabricated on a substrate, comprising:

a drain region of a first conductivity type;

a source region of the first conductivity type;

a drift region of the first conductivity type extending from the drain region in a first direction substantially orthogonal to a bottom surface of the substrate;

a dielectric layer that adjoins the drift region, the dielectric layer having an insulation width in a second direction substantially orthogonal to the first direction;

a field plate member insulated in the second direction from the drift region by the dielectric layer; and

wherein the insulation width varies along the first direction, the insulation width being narrowest near the source region and widest near the drain region.

42. The high-voltage transistor according to claim 41 further comprising:

a source electrode electrically connected to the source region; and

a drain electrode electrically connected to the drain region.

43. The high-voltage transistor according to claim 41 wherein the first conductivity type comprises n-type and the second conductivity type comprises p-type.

44. The high-voltage transistor according to claim 41 further comprising a body region of a second conductivity type opposite to the first conductivity type, the drift region extending from the drain region to the body region.