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

• US 6,787,847 B2
• Filed: 05/30/2002
• Issued: 09/07/2004
• 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:
  US10/158,635
• Publication Number:
  US 20030047769A1
• Time in Patent Office: 831 Days
• Field of Search: 257/302, 257/327-331, 257/339-342, 257/242
• 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 vertical high-voltage transistor comprising:

a substrate;

a source region of a first conductivity type;

a drift region comprising an epitaxial layer of semiconductor material of the first conductivity type that extends in a vertical direction to contact the source region and the substrate, the epitaxial layer having a linearly graded doping profile and the drift region having first and second sidewalls;

first and second dielectric layers disposed along the first and second sidewalls, respectively;

first and second field plate members that respectively extend in the vertical direction adjacent to the first and second dielectric layers, the first and second dielectric layers insulating the first and second field plate members from the first and second sidewalls, respectively, each of the first and second field plate members being insulated from the substrate and oriented substantially in parallel with the first and second sidewalls, respectively;

a source electrode electrically connected to the source region; and

a drain electrode electrically connected to the substrate,

current flowing vertically from the source electrode, through the source region, the drift region, and the substrate, to the drain electrode when the vertical high-voltage transistor operates in an on-state, the drift region being pinched-off when the vertical high-voltage transistor operates in an off-state.

2. The vertical high-voltage transistor according to claim 1 wherein the first conductivity type is n-type.

3. A circuit comprising the vertical high-voltage transistor defined in claim 1 coupled in series with a low-voltage transistor so that when the low-voltage transistor is off, the current flow in the vertical high-voltage transistor is interrupted.

4. A vertical high-voltage transistor comprising:

a substrate;

a source region of a first conductivity type;

a drift region of the first conductivity type that extends in a vertical direction to contact the source region and the substrate, the drift region having first and second sidewalls;

first and second dielectric layers disposed along the first and second sidewalls, respectively;

first and second field plate members that respectively extend in the vertical direction adjacent to the first and second dielectric layers, the first and second dielectric layers insulating the first and second field plate members from the first and second sidewalls, respectively, with a reduced spacing existing between the first and second field plate members and the first and second sidewalls of the drift region, respectively, near the source region, each of the first and second field plate members being insulated from the substrate and oriented substantially in parallel with the first and second sidewalls, respectively;

a source electrode electrically connected to the source region; and

a drain electrode electrically connected to the substrate,

current flowing vertically from the source electrode, through the source region, the drift region, and the substrate, to the drain electrode when the vertical high-voltage transistor operates in an on-state, the drift region being pinched-off when the vertical high-voltage transistor operates in an off-state.

5. A vertical high-voltage transistor comprising:

a substrate;

a source region;

a drift region in contact with the source region, the drift region having first and second sidewalls;

first and second dielectric layers disposed along the first and second sidewalls, respectively;

first and second field plate members disposed adjacent to, and insulated from, the first and second sidewalls, respectively, the first and second field plate members are each insulated from the first and second sidewalls of the drift region by a first spacing near the source region, and by a second spacing near the substrate, the first spacing being smaller than the second spacing, and wherein the first and second field plate members are both insulated from the substrate;

a source electrode electrically connected to the source region; and

a drain electrode electrically connected to the substrate,

wherein current flows from the source electrode, through the source region, the drift region, and the substrate, to the drain electrode when the vertical high-voltage transistor operates in an on-state, the drift region being pinched-off when the vertical high-voltage transistor is in an off-state.

6. The vertical high-voltage transistor according to claim 5 wherein the first and second field plate members are each insulated from the first and second sidewalls of the drift region by a third spacing halfway between the source region and the substrate, the third spacing being larger than the first spacing, but smeller than the second spacing.

7. A vertical high-voltage transistor comprising:

a substrate;

a source region;

a drift region in contact with the source region, the drift region having first and second sidewalls, a lateral width and a vertical height, the lateral width being less than or equal to one-tenth the vertical height of the drift region;

first and second dielectric layers disposed along the first and second sidewalls, respectively;

first and second field plate members insulated from the first and second sidewalls by the first and second dielectric layers, respectively;

a source electrode electrically connected to the source region; and

a drain electrode electrically connected to the substrate.

8. A vertical high-voltage transistor comprising:

a substrate;

a source region of a first conductivity type;

a drift region of the first conductivity type that extends in a vertical direction to contact the source region and the substrate, the drift region having first and second sidewalls;

first and second dielectric layers disposed along the first and second sidewalls, respectively;

first and second field plate members insulated from the first and second sidewalls by the first and second dielectric layers, respectively;

a source electrode electrically connected to the source region; and

a drain electrode electrically connected to the substrate,

a lower portion of the first and second field plate members being respectively separated from the drift region by a lateral thickness of the first and second dielectric layers, the drift region having a lateral width that is less than or equal to the lateral thickness.

9. A vertical high-voltage transistor comprising:

a substrate;

a source region of a first conductivity type;

a drift region of the first conductivity type that extends in a vertical direction to contact the source region and the substrate, the drift region having first and second sidewalls;

first and second dielectric layers disposed along the first and second sidewalls, respectively;

first and second field plate members insulated from the first and second sidewalls by the first and second dielectric layers, respectively, the first and second field plate members having a lateral width that varies in a discontinuous manner along the vertical direction,

a source electrode electrically connected to the source region; and

a drain electrode electrically connected to the substrate.