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

• US 6,781,198 B2
• Filed: 05/30/2002
• Issued: 08/24/2004
• Est. Priority Date: 09/07/2001
• Status: Expired due to Fees

• 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:
  US10/158,637
• Publication Number:
  US 20030047793A1
• Time in Patent Office: 817 Days
• Field of Search: 257/242, 257/302, 257/327-331, 257/339, 257/341-342
• US Class Current: 257/329
• 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 vertical high-voltage transistor comprising:

a drain region of a first conductivity type;

a plurality of body regions 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 one or more of the body regions;

field plate members that extend in the first direction, each of the field plate members being spaced-apart in a second direction and insulated from the drift regions by a dielectric layer;

a plurality of source regions of the first conductivity type, each of the source regions adjoining one of the body regions;

at least one insulated gate member disposed above each body region, thereby defining a channel region that extends in the second direction from one of the source regions to one of the drift regions.

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

a drain electrode electrically connected to the drain region; and

a source electrode electrically connected to the source regions.

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

4. The vertical high-voltage transistor according to claim 1 wherein the drain region comprises a substrate having a substantially planar bottom surface, the first direction is a vertical direction perpendicular to the bottom surface of the substrate, and the second direction is a lateral direction parallel to the bottom surface of the substrate.

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

6. The vertical high-voltage transistor according to claim 1 wherein the drift regions have a doping that is higher near the drain region and lower near the body regions.

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

8. A vertical high-voltage transistor comprising:

a substrate of a first conductivity type;

one or more body regions of a second conductivity type opposite to the first conductivity type;

a drift region of the first conductivity type, the drift region extending in a first direction from the substrate to the one or more body regions, the drift region having first and second sidewalls;

first and second field plate members disposed adjacent to, and insulated from, the first and second sidewalls in a second direction, respectively, the first and second field plate members both being insulated from the substrate;

a source region of the first conductivity type disposed in each of the one or more body regions;

an insulated gate member disposed above the one or more body regions, the insulated gate member extending in the second direction from the source region to the drift region.

9. The vertical high-voltage transistor according to claim 8 further comprising:

a drain electrode electrically connected to the substrate; and

a source electrode electrically connected to the source region.

10. The vertical high-voltage transistor according to claim 8 wherein the drift region has a linearly graded doping profile.

11. The vertical high-voltage transistor according to claim 8 wherein the drift region has a length oriented in the first direction and a width oriented in the second direction, the length being more than five times the width.

12. The vertical high-voltage transistor according to claim 8 wherein the substrate comprises a drain region having a substantially planar bottom surface, the first direction is a vertical direction perpendicular to the bottom surface of the substrate, and the second direction is a lateral direction parallel to the bottom surface of the substrate.

13. The vertical high-voltage transistor according to claim 8 wherein first and second field plate members comprise doped polysilicon.