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

• US 6,987,299 B2
• Filed: 06/16/2004
• Issued: 01/17/2006
• Est. Priority Date: 09/07/2001
• Status: Expired due to Fees

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Paul, Amit, Disney, Donald Ray
• Primary Examiner(s): Zarabian, Amir
• Assistant Examiner(s): Tran, Thanh Y.
• Application Number:
  US10/868,984
• Publication Number:
  US 20040232486A1
• Time in Patent Office: 580 Days
• Field of Search: 257/288, 257/327, 257/367, 257/328, 257/487, 257/490, 438/197, 438/212, 438/268
• US Class Current: 257/327
• 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 emphaized 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 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 fully insulated from the drift regions;

a portion of the dielectric layer separating each drift region from the adjacent field plate member, the portion having a tapered width extending along the first direction, the tapered width being narrowest near the at least one source region and widest near the drain region.

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

a body region of a second conductivity type opposite to the first conductivity type disposed between the at least one source region and the plurality of drift regions.

3. 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 first direction being oriented parallel to the planar bottom surface and the second direction being oriented perpendicular to the planar bottom surface.

4. 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 first and second directions being oriented parallel to the planar bottom surface.

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

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

7. The lateral high-voltage transistor according to claim 1 wherein the drift regions have substantially uniform doping.

8. The lateral high-voltage transistor according to claim 1 wherein the drift regions comprise an epitaxial layer of the semiconductor substrate.

9. The lateral high-voltage transistor according to claim 8 wherein the epitaxial layer is disposed on an insulating layer above the semiconductor substrate.

10. A high-voltage transistor comprising:

a substrate;

a drain region of a first conductivity type;

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

a drift region of the first conductivity type extending in a first direction from the drain region to the body region,

a field plate member separated from the drift region by a dielectric layer, the field plate member being fully insulated from the drift region;

the dielectric layer having a width that is narrowest near the body region and widest near the drain region.

11. The high-voltage transistor according to claim 10 wherein the first direction is oriented perpendicular to a bottom surface of the substrate.

12. The high-voltage transistor according to claim 10 wherein the first direction is oriented parallel to a bottom surface of the substrate.

13. The high-voltage transistor according to claim 10 wherein the drift region has substantially uniform doping.

14. The high-voltage transistor according to claim 10 wherein the drift region has a substantially uniform width.

15. The high-voltage transistor according to claim 10 further comprising:

a source region of the first conductivity type that adjoins the body region and is spaced-apart from the drift region; and

an insulated gate member disposed adjacent to the body region.

16. The high-voltage transistor according to claim 10 wherein the first conductivity type is n-type and the second conductivity type is p-type.

17. The high-voltage transistor according to claim 10 wherein the width of the dielectric layer increases monotonically from near the body region to near the drain region.

18. The high-voltage transistor according to claim 10 wherein the width of the dielectric layer increases linearly from near the body region to near the drain region.

19. The high-voltage transistor according to claim 10 wherein a width of the field plate member varies in an inverse complementary manner with the width of the dielectric layer from near the body region to near the drain region.

20. An extended drain region of a high-voltage transistor comprising:

a plurality of drift regions of the first conductivity type arranged substantially in parallel and extending in a first direction, 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 fully insulated from the drift regions;

wherein separation between the field plate member and each of the adjacent ones of the drift regions is larger at one end of the drift regions and smaller at an opposite end of the drift regions.

21. The extended drain region according to claim 20 wherein the field plate member comprises a conductive material.

22. The extended drain region according to claim 20 wherein the high-voltage transistor is fabricated on a semiconductor substrate having a bottom surface, the first direction being oriented substantially parallel to the bottom surface and the second direction being oriented substantially perpendicular to the bottom surface.

23. The extended drain region according to claim 20 wherein the high-voltage transistor is fabricated on a semiconductor substrate having a bottom surface, the first and second directions being oriented substantially parallel to the bottom surface.

24. The extended drain region according to claim 20 wherein the first conductivity type comprises n-type and the second conductivity type comprises p-type.

25. The extended drain region according to claim 20 wherein the field plate member is tapered in a complementary fashion with respect to the dielectric layer.

26. The extended drain region according to claim 20 wherein the drift regions are substantially uniformly doped.

27. The extended drain region according to claim 20 wherein the drift regions comprise an epitaxial layer of a semiconductor substrate.

28. The extended drain region according to claim 20 wherein a width of each of the adjacent ones of the drift regions is less than a width of the dielectric layer at the opposite end of the drift regions.