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

• US 6,882,005 B2
• Filed: 03/21/2003
• Issued: 04/19/2005
• Est. Priority Date: 09/07/2001
• Status: Expired due to Term

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Disney, Donald Ray
• Primary Examiner(s): Flynn, Nathan J.
• Assistant Examiner(s): MONDT, JOHANNES P
• Application Number:
  US10/393,759
• Publication Number:
  US 20030197220A1
• Time in Patent Office: 760 Days
• Field of Search: 257/242, 257/322, 257300-302, 257328-331, 257/333, 257/339, 257/409
• US Class Current: 257/328
• 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 29/0878 Impurity concentration or distribution
• 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 29/4236 within a trench, e.g. trench gate electrode, groove gate electrode
• CPC Class Codes: H01L 29/42368 the thickness being non-uniform
• CPC Class Codes: H01L 29/66734 with a step of recessing the gate electrode, e.g. to form a trench gate electrode
• 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 29/7828 without inversion channel, e.g. vertical ACCUFETs, normally-on vertical MISFETs

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. With the field plate members at the lowest circuit potential, the transistor supports high voltages applied to the drain in the off-state. 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.

Claims

1. A high-voltage transistor comprising:

a drain region of a first conductivity type;

a source region of the first conductivity type;

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

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 body region, adjacent ones of the drift regions being separated in a second direction orthogonal to the first direction by a dielectric layer;

a field plate member disposed within the dielectric layer, the field plate member being separated from an adjacent drift region by a distance of at least two microns in the second direction; and

an insulated gate disposed adjacent the body region.

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

a source electrode electrically connected to the source region; and

a drain electrode electrically connected to the drain region.

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

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

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

6. The high-voltage transistor according to claim 1 wherein the dielectric layer comprises silicon dioxide.

7. The high-voltage transistor according to claim 1 wherein the drift regions each have a linearly graded doping profile.

8. A high-voltage transistor comprising:

a drain region of a first conductivity type;

a source region of the first conductivity type;

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

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 body region, the drain region and body region separated by a distance of at least fifteen microns in the first direction, adjacent ones of the drift regions being separated in a second direction orthogonal to the first direction by a dielectric layer;

an insulated gate disposed adjacent the body region; and

a field plate member of a highly conductive material disposed within the dielectric layer, a top portion of the field plate member extending above a lowermost portion of the insulated gate.

9. The high-voltage transistor according to claim 8 wherein the first conductivity type comprises n-type and the second conductivity type comprises p-type.

10. The high-voltage transistor according to claim 8 wherein the field plate member comprises heavily doped polysilicon.

11. The high-voltage transistor according to claim 8 wherein the drift regions each have a linearly graded doping profile.

12. A high-voltage transistor comprising:

a drain region of a first conductivity type;

a source region of the first conductivity type;

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

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 body region, adjacent ones of the drift regions being separated in a second direction orthogonal to the first direction by a dielectric layer;

an insulated gate disposed adjacent the body region; and

a field plate member disposed within the dielectric layer, a top portion of the field plate member extending above a lowermost portion of the insulated gate.

13. The high-voltage transistor according to claim 12 further comprising:

a source electrode electrically connected to the source region; and

a drain electrode electrically connected to the drain region.

14. The high-voltage transistor according to claim 12 wherein the high-voltage transistor is fabricated on a semiconductor substrate having a planar bottom surface, the first direction being oriented substantially perpendicular to the planar bottom surface and the second direction being oriented substantially parallel to the planar bottom surface.

15. The high-voltage transistor according to claim 12 wherein the first conductivity type comprises n-type and the second conductivity type comprises p-type.

16. The high-voltage transistor according to claim 12 wherein the at least one field plate member comprises heavily doped polysilicon.

17. The high-voltage transistor according to claim 12 wherein the drift regions have a doping that is higher near the drain region and lower near the body region.

18. The high-voltage transistor according to claim 12 wherein the drift regions each have a linearly graded doping profile.

19. A high-voltage transistor comprising:

a drain region of a first conductivity type;

a source region of the first conductivity type;

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

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 body region, the drain region and body region separated by a distance of at least fifteen microns in the first direction, adjacent ones of the drift regions being separated in a second direction orthogonal to the first direction by a dielectric layer;

an insulated gate disposed adjacent the body region; and

a field plate member disposed within the dielectric layer and electrically isolated from the drain region, a top portion of the field plate member extending above a lowermost portion of the insulated gate.

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

21. The high-voltage transistor according to claim 19 wherein the field plate member comprises a metal or metal alloy.

22. A high-voltage transistor comprising:

a drain region of a first conductivity type;

a source region of the first conductivity type;

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

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 body region, the drain region and body region separated by a distance of at least fifteen microns in the first direction, adjacent ones of the drift regions being separated in a second direction orthogonal to the first direction by a dielectric layer;

a field plate member disposed within the dielectric layer and separated from an adjacent drift region by a distance of at least two microns in the second direction; and

an insulated gate disposed adjacent the body region.

23. The high-voltage transistor according to claim 22 wherein the first conductivity type comprises n-type and the second conductivity type comprises p-type.

24. The high-voltage transistor according to claim 22 wherein the field plate member comprises a metal or metal alloy.

25. The high-voltage transistor according to claim 22 wherein the field plate member comprises heavily doped polysilicon.