SEMICONDUCTOR DEVICE

• US 20110284837A1
• Filed: 05/11/2011
• Published: 11/24/2011
• Est. Priority Date: 05/20/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: NISHIJIMA, Tatsuji
• Granted Patent: US 8,624,239 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• CPC Class Codes: H01L 29/41733 for thin film transistors with insulated gate
• CPC Class Codes: H01L 29/45 Ohmic electrodes
• CPC Class Codes: H01L 29/78648 arranged on opposing sides of the channel
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

In a transistor, a drain electrode to which a high electric field is applied is formed over a flat surface, and an end portion of a gate electrode on the drain electrode side in a channel width direction and an end portion of the gate electrode in a channel length direction are covered with an oxide semiconductor with a gate insulating layer between the gate electrode and the oxide semiconductor layer, so that withstand voltage of the transistor is improved. Further, a semiconductor device for high power application, in which the transistor is used, can be provided.

Claims

1. A semiconductor device comprising:

a gate electrode;

a gate insulating layer covering the gate electrode;

an oxide semiconductor layer over the gate insulating layer;

a first source electrode and a first drain electrode in direct contact with the oxide semiconductor layer at a first region;

an insulating layer covering the oxide semiconductor layer, the first source electrode, and the first drain electrode; and

a second source electrode and a second drain electrode over the insulating layer, which are electrically connected to the first source electrode and the first drain electrode, respectively,

wherein the first region is in a second region where the oxide semiconductor layer and the gate electrode overlap with each other,

wherein a length of the oxide semiconductor layer in a channel length direction is longer than a length of the gate electrode in the channel length direction,

wherein the second drain electrode includes a portion overlapping with the gate electrode, and

wherein the oxide semiconductor layer is between the second drain electrode and the gate electrode at the portion.

6. The semiconductor device according to claim 1, wherein the first region is in a surface of the oxide semiconductor layer, which is substantially parallel to an upper surface of the gate electrode.

10. The semiconductor device according to claim 1, wherein the oxide semiconductor layer comprises indium.

14. The semiconductor device according to claim 1, wherein the semiconductor device is a power MOSFET.

2. A semiconductor device comprising:

a gate electrode;

a gate insulating layer covering the gate electrode;

an oxide semiconductor layer over the gate insulating layer;

a first source electrode and a first drain electrode in direct contact with the oxide semiconductor layer at a first region;

a first insulating layer covering the oxide semiconductor layer, the first source electrode, and the first drain electrode;

a first conductive layer over the first insulating layer;

a second insulating layer covering the first conductive layer; and

a second source electrode electrically connected to the first source electrode, a second drain electrode electrically connected to the first drain electrode, and a second conductive layer electrically connected to the first conductive layer, which are over the first insulating layer,

wherein the first region is in a second region where the oxide semiconductor layer and the gate electrode overlap with each other,

wherein a length of the oxide semiconductor layer in a channel length direction is longer than a length of the gate electrode in the channel length direction,

wherein the second drain electrode includes a portion overlapping with the gate electrode, and

wherein the oxide semiconductor layer is between the second drain electrode and the gate electrode at the portion.

7. The semiconductor device according to claim 2, wherein the first region is in a surface of the oxide semiconductor layer, which is substantially parallel to an upper surface of the gate electrode.

11. The semiconductor device according to claim 2, wherein the oxide semiconductor layer comprises indium.

15. The semiconductor device according to claim 2, wherein the semiconductor device is a power MOSFET.

18. The semiconductor device according to claim 2, wherein the first conductive layer is formed over a surface of the first insulating layer, which is substantially parallel to an upper surface of the gate electrode.

3. A semiconductor device comprising:

a gate electrode;

a gate insulating layer covering the gate electrode;

an oxide semiconductor layer over the gate insulating layer;

a plurality of first source electrodes and a plurality of first drain electrodes which are in direct contact with the oxide semiconductor layer at a first region;

an insulating layer covering the oxide semiconductor layer, the plurality of first source electrodes, and the plurality of first drain electrodes; and

a second source electrode electrically connected to each of the first source electrodes and a second drain electrode electrically connected to each of the first drain electrodes, which are over the insulating layer,

wherein the first region is in a second region where the oxide semiconductor layer and the gate electrode overlap with each other,

wherein a length of the oxide semiconductor layer in a channel length direction is longer than a length of the gate electrode in the channel length direction,

wherein the second drain electrode includes a portion overlapping with the gate electrode, and

wherein the oxide semiconductor layer is between the second drain electrode and the gate electrode at the portion.

8. The semiconductor device according to claim 3, wherein the first region is in a surface of the oxide semiconductor layer, which is substantially parallel to an upper surface of the gate electrode.

12. The semiconductor device according to claim 3, wherein the oxide semiconductor layer comprises indium.

16. The semiconductor device according to claim 3, wherein the semiconductor device is a power MOSFET.

4. A semiconductor device comprising:

a gate electrode;

a gate insulating layer covering the gate electrode;

an oxide semiconductor layer over the gate insulating layer;

a plurality of first source electrodes and a plurality of first drain electrodes which are in direct contact with the oxide semiconductor layer at a first region;

a first insulating layer covering the oxide semiconductor layer, the plurality of first source electrodes, and the plurality of first drain electrodes;

a first conductive layer over the first insulating layer;

a second insulating layer covering the first conductive layer; and

a second source electrode electrically connected to each of the first source electrodes, a second drain electrode electrically connected to each of the first drain electrodes, and a second conductive layer electrically connected to the first conductive layer, which are over the first insulating layer,

wherein the first region is in a second region where the oxide semiconductor layer and the gate electrode overlap with each other,

wherein a length of the oxide semiconductor layer in a channel length direction is longer than a length of the gate electrode in the channel length direction,

wherein the second drain electrode includes a portion overlapping with the gate electrode, and

wherein the oxide semiconductor layer is between the second drain electrode and the gate electrode at the portion.

5. The semiconductor device according to claim 4, wherein the first conductive layer does not overlap with the second drain electrode.

9. The semiconductor device according to claim 4, wherein the first region is in a surface of the oxide semiconductor layer, which is substantially parallel to an upper surface of the gate electrode.

13. The semiconductor device according to claim 4, wherein the oxide semiconductor layer comprises indium.

17. The semiconductor device according to claim 4, wherein the semiconductor device is a power MOSFET.

19. The semiconductor device according to claim 4, wherein the first conductive layer is formed over a surface of the first insulating layer, which is substantially parallel to an upper surface of the gate electrode.