SEMICONDUCTOR DEVICE

• US 20150214379A1
• Filed: 04/02/2015
• Published: 07/30/2015
• Est. Priority Date: 03/27/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: YAMAZAKI, Shunpei, ABE, Takayuki, SHISHIDO, Hideaki
• Granted Patent: US 9,705,003 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 29/42376 characterised by the length or the sectional shape
• CPC Class Codes: H01L 29/42384 for thin film field effect transistors, e.g. characterised by the thickness or the shape of the insulator or the dimensions, the shape or the lay-out of the conductor
• CPC Class Codes: H01L 29/78606 with supplementary region or layer in the thin film or in the insulated bulk substrate supporting it for controlling or increasing the safety of the device H01L29/78642, H01L29/78645 take precedence
• CPC Class Codes: H01L 29/78645 with multiple gate
• 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
• CPC Class Codes: H10K 59/123 Connection of the pixel electrodes to the thin film transistors [TFT]

Abstract

The threshold voltage is shifted in a negative or positive direction in some cases by an unspecified factor in a manufacturing process of the thin film transistor. If the amount of shift from 0 V is large, driving voltage is increased, which results in an increase in power consumption of a semiconductor device. Thus, a resin layer having good flatness is formed as a first protective insulating film covering the oxide semiconductor layer, and then a second protective insulating film is formed by a sputtering method or a plasma CVD method under a low power condition over the resin layer. Further, in order to adjust the threshold voltage to a desired value, gate electrodes are provided over and below an oxide semiconductor layer.

Claims

1. A semiconductor device comprising:

a gate electrode;

a gate insulating layer over the gate electrode;

an oxide semiconductor layer over the gate insulating layer;

a first insulating layer over the oxide semiconductor layer;

a second insulating layer over the first insulating layer; and

wherein the second insulating layer comprises one compound selected from the group consisting of silicon nitride, silicon oxynitride, and silicon nitride oxide.

2. The semiconductor device according to claim 1, wherein a width of the gate electrode is larger than a width of the oxide semiconductor layer in a channel length direction of the oxide semiconductor layer.

3. The semiconductor device according to claim 1, further comprising:

a first electrode layer and a second electrode layer over and in contact with the oxide semiconductor layer.

4. The semiconductor device according to claim 3, further comprising:

a first buffer layer between the oxide semiconductor layer and the first electrode layer, and

a second buffer layer between the oxide semiconductor layer and the second electrode layer.

5. The semiconductor device according to claim 3, further comprising:

a cathode electrically connected to the first electrode layer or the second electrode layer;

a light-emitting layer over the cathode; and

an anode over the light-emitting layer.

6. A semiconductor device comprising:

a first gate electrode;

a gate insulating layer over the first gate electrode;

an oxide semiconductor layer over the gate insulating layer;

a first insulating layer over the oxide semiconductor layer;

a second insulating layer over the first insulating layer; and

a second gate electrode over the second insulating layer,

wherein the second insulating layer comprises one compound selected from the group consisting of silicon nitride, silicon oxynitride, and silicon nitride oxide, and

wherein both the first gate electrode and the second gate electrode extend beyond side edges of the oxide semiconductor layer in a channel width direction of the oxide semiconductor layer.

7. The semiconductor device according to claim 6, wherein the second gate electrode overlaps with the oxide semiconductor layer and the first gate electrode.

8. The semiconductor device according to claim 6, wherein a width of the second gate electrode is larger than a width of the first gate electrode in a channel length direction of the oxide semiconductor layer.

9. The semiconductor device according to claim 6, wherein a width of the first gate electrode is larger than a width of the oxide semiconductor layer in a channel length direction of the oxide semiconductor layer.

10. The semiconductor device according to claim 6, wherein the second gate electrode is in a floating state.

11. The semiconductor device according to claim 6, wherein the second gate electrode is a fixed potential of 0V.

12. The semiconductor device according to claim 6, wherein the first gate electrode and the second gate electrode have the same potential.

13. The semiconductor device according to claim 6, wherein the second gate electrode is electrically connected to the first gate electrode.

14. The semiconductor device according to claim 6, further comprising:

a first electrode layer and a second electrode layer over and in contact with the oxide semiconductor layer.

15. The semiconductor device according to claim 14, wherein one of the first electrode layer and the second electrode layer is in direct contact with the oxide semiconductor layer and the second gate electrode.

16. The semiconductor device according to claim 14, further comprising:

a first buffer layer between the oxide semiconductor layer and the first electrode layer, and

a second buffer layer between the oxide semiconductor layer and the second electrode layer.

17. The semiconductor device according to claim 14 further comprising:

a cathode electrically connected to the first electrode layer or the second electrode layer;

a light-emitting layer over the cathode; and

an anode over the light-emitting layer.