SEMICONDUCTOR DEVICE AND MANUFACTURING METHOD THEREOF

• US 20110140109A1
• Filed: 12/06/2010
• Published: 06/16/2011
• Est. Priority Date: 12/11/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: AKIMOTO, Kengo, YAMAZAKI, Shunpei
• Granted Patent: US 8,563,976 B2
• Time in Patent Office: Days
• US Class Current: 257/57
• 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 29/45 Ohmic electrodes
• CPC Class Codes: H01L 29/66742 Thin film unipolar transistors
• 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

A semiconductor device includes an oxide semiconductor layer including a channel formation region which includes an oxide semiconductor having a wide band gap and a carrier concentration which is as low as possible, and a source electrode and a drain electrode which include an oxide conductor containing hydrogen and oxygen vacancy, and a barrier layer which prevents diffusion of hydrogen and oxygen between an oxide conductive layer and the oxide semiconductor layer. The oxide conductive layer and the oxide semiconductor layer are electrically connected to each other through the barrier layer.

Claims

1. A semiconductor device comprising:

a first gate electrode over an insulating surface of a substrate having a light-transmitting property, the first gate electrode having a light-transmitting property;

a first insulating layer over the first gate electrode;

a first oxide semiconductor layer over the first insulating layer;

a barrier layer over the first oxide semiconductor layer, the barrier layer having a light-transmitting property;

a first electrode over the first oxide semiconductor layer with the barrier layer interposed therebetween, the first electrode overlapping with the first gate electrode;

a second electrode over the first oxide semiconductor layer with the barrier layer interposed therebetween, the second electrode overlapping with the first gate electrode; and

a second insulating layer over the first electrode and the second electrode and in contact with a part of the first oxide semiconductor layer,

wherein the barrier layer includes nitride,

wherein a carrier concentration of the first oxide semiconductor layer is lower than 1×

10¹⁴/cm³, and

wherein the first electrode and the second electrode each includes an oxide conductor having a light-transmitting property and a resistivity of 2000×

10<sup>−

6</sup> Ω

·

cm or lower.

2. The semiconductor device according to claim 1, further comprising a gate wiring electrically connected to the first gate electrode, wherein the gate wiring includes metal.

3. The semiconductor device according to claim 1, further comprising a signal line electrically connected to the first electrode and the second electrode through openings formed in the second insulating layer, wherein the signal line includes metal.

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

a gate wiring electrically connected to the first gate electrode;

a signal line electrically connected to the first electrode and the second electrode through openings formed in the second insulating layer; and

a third insulating layer over the signal line,

wherein the third insulating layer is on and in contact with the first insulating layer around the semiconductor device.

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

a first capacitor electrode over the substrate; and

a second capacitor electrode over the first capacitor electrode with the first insulating layer interposed therebetween,

wherein the first capacitor electrode includes a same material as the first gate electrode, and

wherein the second capacitor electrode includes a same material as the first electrode and the second electrode.

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

a gate wiring electrically connected to the first gate electrode; and

a signal line electrically connected to the first electrode and the second electrode through openings formed in the second insulating layer,

wherein the first insulating layer, the second insulating layer, and the first oxide semiconductor layer are sandwiched between the gate wiring and the signal line at an intersection of the gate wiring and the signal line.

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

a gate wiring electrically connected to the first gate electrode;

a signal line electrically connected to the first electrode and the second electrode through openings formed in the second insulating layer;

a second gate electrode over the insulating surface of the substrate;

a second oxide semiconductor layer over the second gate electrode with the first insulating layer interposed therebetween;

a channel protective layer overlapping with a channel formation region of the second oxide semiconductor layer;

a third electrode overlapping with the channel protective layer; and

a fourth electrode overlapping with the channel protective layer,

wherein the second gate electrode includes a same material as the gate wiring,

wherein the channel protective layer includes a same material as the second insulating layer, and

wherein the third electrode and the fourth electrode each includes a same material as the signal line.

8. The semiconductor device according to claim 1,

wherein the barrier layer comprises a layer selected from a titanium nitride layer, a tantalum nitride layer, a tungsten nitride layer, a molybdenum nitride layer, a silicon nitride layer and an aluminum nitride layer.

9. The semiconductor device according to claim 1,

wherein the first insulating layer has a stacked structure comprising a first layer and a second layer, and

wherein the first layer and the second layer each comprises a material selected from silicon nitride, silicon oxide, silicon nitride oxide and silicon oxynitride.

10. An electronic appliance comprising the semiconductor device according to claim 1.

11. A semiconductor device comprising:

a first gate electrode over an insulating surface of a substrate having a light-transmitting property, the first gate electrode having a light-transmitting property;

a first insulating layer over the first gate electrode;

a first oxide semiconductor layer over the first insulating layer;

a first barrier layer over the first oxide semiconductor layer, the first barrier layer having a light-transmitting property;

a second barrier layer over the first oxide semiconductor layer, the second barrier layer having a light-transmitting property;

a first electrode over the first oxide semiconductor layer with the first barrier layer interposed therebetween, the first electrode overlapping with the first gate electrode;

a second electrode over the first oxide semiconductor layer with the second barrier layer interposed therebetween, the second electrode overlapping with the first gate electrode; and

a second insulating layer over the first electrode and the second electrode and in contact with a part of the first oxide semiconductor layer,

wherein the first barrier layer and the second barrier layer include nitride;

wherein a carrier concentration of the first oxide semiconductor layer is lower than 1×

10¹⁴/cm³, and

wherein the first electrode and the second electrode each includes an oxide conductor having a light-transmitting property and a resistivity of 2000×

10<sup>−

6</sup> Ω

·

cm or lower.

12. The semiconductor device according to claim 11, further comprising a gate wiring electrically connected to the first gate electrode, wherein the gate wiring includes metal.

13. The semiconductor device according to claim 11, further comprising a signal line electrically connected to the first electrode and the second electrode through openings formed in the second insulating layer, wherein the signal line includes metal.

14. The semiconductor device according to claim 11, further comprising:

a gate wiring electrically connected to the first gate electrode;

a signal line electrically connected to the first electrode and the second electrode through openings formed in the second insulating layer; and

a third insulating layer over the signal line,

wherein the third insulating layer is on and in contact with the first insulating layer around the semiconductor device.

15. The semiconductor device according to claim 11, further comprising:

a first capacitor electrode over the substrate; and

a second capacitor electrode over the first capacitor electrode with the first insulating layer interposed therebetween,

wherein the first capacitor electrode includes a same material as the first gate electrode, and

wherein the second capacitor electrode includes a same material as the first electrode and the second electrode.

16. The semiconductor device according to claim 11, further comprising:

a gate wiring electrically connected to the first gate electrode; and

a signal line electrically connected to the first electrode and the second electrode through openings formed in the second insulating layer,

wherein the first insulating layer, the second insulating layer, and the first oxide semiconductor layer are sandwiched between the gate wiring and the signal line at an intersection of the gate wiring and the signal line.

17. The semiconductor device according to claim 11, further comprising:

a gate wiring electrically connected to the first gate electrode;

a signal line electrically connected to the first electrode and the second electrode through openings formed in the second insulating layer,

a second gate electrode over the insulating surface of the substrate;

a second oxide semiconductor layer over the second gate electrode with the first insulating layer interposed therebetween;

a channel protective layer overlapping with a channel formation region of the second oxide semiconductor layer;

a third electrode overlapping with the channel protective layer; and

a fourth electrode overlapping with the channel protective layer,

wherein the second gate electrode includes a same material as the gate wiring,

wherein the channel protective layer includes a same material as the second insulating layer, and

wherein the third electrode and the fourth electrode each includes a same material as the signal line.

18. The semiconductor device according to claim 11,

wherein the first barrier layer and the second barrier layer each comprises a layer selected from a titanium nitride layer, a tantalum nitride layer, a tungsten nitride layer, a molybdenum nitride layer, a silicon nitride layer and an aluminum nitride layer.

19. The semiconductor device according to claim 11,

wherein the first insulating layer has a stacked structure comprising a first layer and a second layer, and

wherein the first layer and the second layer each comprises a material selected from silicon nitride, silicon oxide, silicon nitride oxide and silicon oxynitride.

20. An electronic appliance comprising the semiconductor device according to claim 11.

21. A method for manufacturing a semiconductor device, comprising the steps of:

forming a gate electrode over an insulating surface of a substrate having a light-transmitting property, the gate electrode including an oxide conductor having a light-transmitting property;

forming a first insulating layer over the gate electrode;

forming an oxide semiconductor layer over the first insulating layer, the oxide semiconductor layer having a light-transmitting property;

performing heat treatment on the substrate after forming the oxide semiconductor layer so that a temperature of the substrate is higher than or equal to 350°

C. and lower than or equal to 700°

C.;

forming a barrier layer to cover the oxide semiconductor layer;

forming an oxide conductive layer over the barrier layer in a reduced atmosphere, the oxide conductive layer having a light-transmitting property;

etching the oxide conductive layer so that a first electrode is formed over the oxide semiconductor layer with the barrier layer interposed therebetween, and a second electrode is formed over the oxide semiconductor layer with the barrier layer interposed therebetween; and

forming a second insulating layer over the oxide semiconductor layer, the first electrode, and the second electrode,

wherein the first electrode overlaps with the gate electrode, and electrically connects with the oxide semiconductor layer through the barrier layer,

wherein the second electrode overlaps with the gate electrode, and electrically connects with the oxide semiconductor layer through the barrier layer,

wherein a carrier concentration of the oxide semiconductor layer is lower than 1×

10¹⁴/cm³, and

wherein the first electrode and the second electrode each includes an oxide conductor having a light-transmitting property and a resistivity of 2000×

10<sup>−

6</sup> Ω

·

cm or lower.

22. The method for manufacturing a semiconductor device according to claim 21,

wherein the heat treatment is performed in atmosphere including a nitrogen gas or a rare gas.

23. The method for manufacturing a semiconductor device according to claim 21,

wherein the barrier layer is etched to form a first barrier layer and a second barrier layer in etching the oxide conductive layer so that the first electrode is on and in contact with the first barrier layer, and the second electrode is on and in contact with the second barrier layer.

24. The method for manufacturing a semiconductor device according to claim 21, further comprising a step of:

performing heat treatment on the substrate at a temperature higher than or equal to 200°

C. and lower than or equal to 400°

C. after forming the second insulating layer.