TRENCH GATE MOSFET

• US 20150008515A1
• Filed: 09/26/2014
• Published: 01/08/2015
• Est. Priority Date: 07/13/2012
• Status: Abandoned Application

• Current Assignee: UBIQ Semiconductor Corp.
• Original Assignee: UBIQ Semiconductor Corp.
• Inventors: Chan, Chien-Ling, Lee, Chi-Hsiang
• Application Number:
  US14/497,340
• Publication Number:
  US 20150008515A1
• Time in Patent Office: Days
• US Class Current: 257/330
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/41766 with at least part of the source or drain electrode having contact below the semiconductor surface, e.g. the source or drain electrode formed at least partially in a groove or with inclusions of conductor inside the semiconductor H01L29/41733 - H01L29/41758 take precedence
• CPC Class Codes: H01L 29/42368 the thickness being non-uniform
• CPC Class Codes: H01L 29/4916 the conductor material next to the insulator being a silicon layer, e.g. polysilicon doped with boron, phosphorus or nitrogen H01L29/4908, H01L29/4983 take precedence
• CPC Class Codes: H01L 29/66727 with a step of recessing the source electrode
• 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 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236
• CPC Class Codes: H01L 29/7827 Vertical transistors H01L29/7802, H01L29/78642 take precedence

Abstract

A trench gate MOSFET is provided. An epitaxial layer is disposed on a substrate. A body layer is disposed in the epitaxial layer. The epitaxial layer has a first trench therein, the body layer has a second trench therein, the first trench is disposed below the second trench, and first trench is narrower than the second trench.

A first insulating layer is disposed on a surface of the first trench. A first conductive layer fills up the first trench and extends into the second trench. A second conductive layer fills up the second trench. A second insulating layer is disposed between the second conductive layer and each of the body layer and the first conductive layer. A dielectric layer is disposed on the epitaxial layer and covers the second conductive layer. Two doped regions are disposed in the body layer respectively beside the second trench.

Claims

1. A trench gate MOSFET, comprising:

a substrate with a first conductivity type;

an epitaxial layer with the first conductivity type disposed on the substrate;

a body layer with a second conductivity type disposed in the epitaxial layer, wherein the epitaxial layer has a first trench therein, the body layer has a second trench therein, the first trench is disposed below the second trench, and a width of the first trench is smaller than a width of the second trench;

a first insulating layer disposed on a surface of the first trench;

a first conductive layer filling up the first trench and extending into the second trench;

a second conductive layer filling up the second trench;

a second insulating layer disposed between the second conductive layer and the body layer, and between the second conductive layer and the first conductive layer;

a dielectric layer disposed on the epitaxial layer and covering the second conductive layer; and

two doped regions with the first conductivity type disposed in the body layer respectively beside the second trench.

2. The trench gate MOSFET as recited in claim 1, wherein a thickness of the second insulating layer is smaller than a thickness of the first insulating layer.

3. The trench gate MOSFET as recited in claim 1, wherein a top of the first conductive layer is not planar.

4. The trench gate MOSFET as recited in claim 1, wherein a material of the first conductive layer comprises doped polysilicon.

5. The trench gate MOSFET as recited in claim 1, wherein a material of the second conductive layer comprises doped polysilicon.

6. The trench gate MOSFET as recited claim 1 further comprising a third conductive layer disposed on the dielectric layer, wherein the third conductive layer is electrically connected to the body layer via two conductor plugs.

7. The trench gate MOSFET as recited in claim 6, wherein a material of the third conductive layer comprises metal.

8. The trench gate MOSFET as recited in claim 1, wherein the first conductivity type is N-type and the second conductivity type is P-type;

or the first conductivity type is P-type and the second conductivity type is N-type.

9. A trench gate MOSFET, comprising:

a substrate with a first conductivity type;

an epitaxial layer with the first conductivity type disposed on the substrate;

a body layer with a second conductivity type disposed in the epitaxial layer, wherein the epitaxial layer has a first trench therein, the body layer has a second trench therein, and the first trench is disposed below the second trench;

a first conductive layer at least disposed in the first trench;

a second conductive layer disposed in the second trench and surrounding an upper portion of the first conductive layer, wherein the second conducitve layer is electrically insulated from the first conductive layer;

a dielectric layer disposed on the epitaxial layer and covering the second conductive layer; and

two doped regions with the first conductivity type disposed in the body layer respectively beside the second trench.

10. The trench gate MOSFET as recited in claim 9, wherein the first conductive layer is electrically insulated from the epitaxial layer.

11. The trench gate MOSFET as recited in claim 9, wherein the second conductive layer is electrically insulated from the body layer.

12. The trench gate MOSFET as recited in claim 9, wherein the first conductive layer further extends into the second trench.

13. The trench gate MOSFET as recited in claim 9, wherein a material of the first conductive layer comprises doped polysilicon.

14. The trench gate MOSFET as recited in claim 9, wherein a material of the second conductive layer comprises doped polysilicon.

15. The trench gate MOSFET as recited claim 9, further comprising a third conductive layer disposed on the dielectric layer, wherein the third conductive layer is electrically connected to the body layer via two conductor plugs.

16. The trench gate MOSFET as recited in claim 15, wherein a material of the third conductive layer comprises metal.

17. The trench gate MOSFET as recited in claim 9, wherein the first conductivity type is N-type and the second conductivity type is P-type;

or the first conductivity type is P-type and the second conductivity type is N-type.