High-voltage metal oxide semiconductor device and fabrication method thereof

• US 8,222,689 B2
• Filed: 09/30/2008
• Issued: 07/17/2012
• Est. Priority Date: 09/30/2008
• Status: Active Grant

• Current Assignee: Niko Semiconductor Co., Ltd
• Original Assignee: Niko Semiconductor Co., Ltd
• Inventors: Tu, Kao-Way
• Primary Examiner(s): Tran, Tony
• Application Number:
  US12/285,179
• Publication Number:
  US 20100078737A1
• Time in Patent Office: 1,386 Days
• Field of Search: 257/409
• US Class Current: 257/329
• CPC Class Codes: H01L 29/0619 with a supplementary region doped oppositely to or in rectifying contact with the semiconductor containing or contacting region, e.g. guard rings with PN or Schottky junction
• CPC Class Codes: H01L 29/0623 Buried supplementary region, e.g. buried guard ring multi-RESURF H01L29/0634
• CPC Class Codes: H01L 29/0634 Multiple reduced surface field (multi-RESURF) structures, e.g. double RESURF, charge compensation, cool, superjunction (SJ), 3D-RESURF, composite buffer (CB) structures
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/42376 characterised by the length or the sectional shape
• 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 29/7808 the other device being a breakdown diode, e.g. Zener diode
• CPC Class Codes: H01L 29/7811 with an edge termination structure guard regions per se H01L29/0619; field plates per se H01L29/402
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236

Abstract

A high-voltage metal oxide semiconductor device comprising a main body of a first conductivity type, a conductive structure, a first well of a second conductivity type, a source region of the first conductivity type, and a second well of the second conductivity type is provided. The conductive structure has a first portion and a second portion. The first portion is extended from an upper surface of the main body into the main body. The second portion is extended along the upper surface of the main body. The first well is located in the main body and below the second portion. The first well is kept away from the first portion with a predetermined distance. The source region is located in the first well. The second well is located in the main body and extends from a bottom of the first portion to a place close to a drain region.

Claims

1. A high-voltage metal oxide semiconductor device comprising:

a main body of a first conductivity type;

a conductive structure, having a first portion and a second portion, the first portion extending from an upper surface of the main body into the main body, and the second portion extending along the upper surface of the main body;

a first well of a second conductivity type, located in the main body below the second portion, and kept away from the first portion with a predetermined distance through a portion of the main body of the first conductivity type located between the first well and the first portion;

a source region of the first conductivity type, located in the first well; and

a second well of the second conductivity type, located in the main body and extending from a bottom of the first portion to a place close to a drain region;

wherein the conductive structure is electrically connected to a gate electrode, the conductive structure and the second well are located under the gate electrode, and an extending distance of the first portion of the conductive structure is greater than a depth of the first well; and

wherein when a voltage difference between the gate electrode and a source electrode is greater than a threshold voltage, a channel is formed in the first well under the second portion to connect the source region and the main body, and the channel is a lateral channel.

2. The high-voltage metal oxide semiconductor device as claimed in claim 1, wherein the first portion is connected to the second portion.

3. The high-voltage metal oxide semiconductor device as claimed in claim 1, wherein a dielectric layer is interposed between the first portion and the second portion, the first portion is electrically connected to the source region, and the second portion is electrically connected to a gate electrode.

4. The high-voltage metal oxide semiconductor device as claimed in claim 1, wherein the drain region is located on a bottom of the main body.

5. The high-voltage metal oxide semiconductor device as claimed in claim 1, wherein the second well and the first portion are separated by at least an oxide layer and a potential of the second well depends on a potential of the first portion of the conductive structure.

6. The high-voltage metal oxide semiconductor device as claimed in claim 1, wherein a width of the second well is greater than a width of the first portion.