SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE

• US 20110012117A1
• Filed: 07/14/2010
• Published: 01/20/2011
• Est. Priority Date: 07/18/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: KUWABARA, Hideaki, MIYAKE, Hiroyuki, YAMAZAKI, Shunpei, SAKATA, Junichiro
• Granted Patent: US 8,729,550 B2
• Time in Patent Office: Days
• US Class Current: 257/59
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• 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 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• CPC Class Codes: H01L 27/1262 with a particular formation, treatment or coating of the substrate
• CPC Class Codes: H01L 29/45 Ohmic electrodes
• 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 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

An object is to reduce the manufacturing cost of a semiconductor device. An object is to improve the aperture ratio of a semiconductor device. An object is to make a display portion of a semiconductor device display a higher-definition image. An object is to provide a semiconductor device which can be operated at high speed. The semiconductor device includes a driver circuit portion and a display portion over one substrate. The driver circuit portion includes: a driver circuit TFT in which source and drain electrodes are formed using a metal and a channel layer is formed using an oxide semiconductor; and a driver circuit wiring formed using a metal. The display portion includes: a pixel TFT in which source and drain electrodes are formed using an oxide conductor and a semiconductor layer is formed using an oxide semiconductor; and a display wiring formed using an oxide conductor.

Claims

1. A semiconductor device comprising:

a pixel portion including a first transistor over a substrate,

a driver circuit including a second transistor over the substrate;

wherein the first transistor comprising;

a first gate electrode over the substrate;

a gate insulating layer over the first gate electrode;

a first oxide semiconductor layer over the gate insulating layer;

a first channel protective layer over and in contact with a part of the first oxide semiconductor layer;

a first source electrode and a first drain electrode over the first channel protective layer and the first oxide semiconductor layer; and

a pixel electrode electrically connected to the first channel protective layer,

wherein the second transistor comprising;

a second gate electrode over the substrate;

the gate insulating layer over the second gate electrode;

a second oxide semiconductor layer over the gate insulating layer;

a second channel protective layer over and in contact with a part of the second oxide semiconductor layer; and

a second source electrode and a second drain electrode over the second channel protective layer and the second oxide semiconductor layer,

wherein the first gate electrode, the gate insulating layer, the first oxide semiconductor layer, the first source electrode, the first drain electrode, the first channel protective layer, and the pixel electrode have a light-transmitting property,

wherein a first material included in the first source electrode and the first drain electrode is different from a second material included in the second source electrode and the second drain electrode, and

wherein a resistivity of the second material is lower than a resistivity of the first material.

2. The semiconductor device according to claim 1, wherein the second transistor comprises:

a back-gate electrode over a channel formation region of the second oxide semiconductor layer with the second channel protective layer interposed therebetween.

3. The semiconductor device according to claim 1, wherein the first channel protective layer and the second channel protective layer comprise the same insulating material which has a light-transmitting property.

4. The semiconductor device according to claim 1, wherein the second source electrode and the second drain electrode are a film formed using an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W, or a stacked film including the film and an alloy film thereof.

5. The semiconductor device according to claim 1, wherein the first source electrode, the first drain electrode, and the pixel electrode comprise any of indium oxide, an alloy of indium oxide and tin oxide, an alloy of indium oxide and zinc oxide, and zinc oxide.

6. The semiconductor device according to claim 1, further comprises a capacitor portion over the substrate,

wherein the capacitor portion comprises:

a capacitor wiring; and

a capacitor electrode overlapping with the capacitor wiring, and

wherein the capacitor wiring and the capacitor electrode have a light-transmitting property.

7. The semiconductor device according to claim 1,

wherein the first channel protective layer and the second channel protective layer comprise an oxide insulating film.

8. The semiconductor device according to claim 1,

wherein a first portion of the first oxide semiconductor layer is in contact with the first channel protective layer,

wherein a second portion of the first oxide semiconductor layer is not in contact with the first channel protective layer, and

wherein a carrier concentration of the second portion is larger than a carrier concentration of the first portion.

9. The semiconductor device according to claim 1,

wherein a first portion of the first oxide semiconductor layer is in contact with the first channel protective layer,

wherein a second portion of the first oxide semiconductor layer is not in contact with the first channel protective layer, and

wherein a carrier concentration of the first portion is less than 1×

10¹⁷/cm³, and

wherein a carrier concentration of the second portion is equal to or more than 1×

10¹⁷/cm³.

10. A method for manufacturing a semiconductor device comprising:

forming a first gate electrode over a pixel portion of a substrate;

forming a second gate electrode over a driver circuit portion of the substrate;

forming a gate insulating layer over the first gate electrode and the second gate electrode;

forming a first oxide semiconductor layer and a second oxide semiconductor layer over the gate insulating layer;

performing dehydration or dehydrogenation of the first oxide semiconductor layer and the second oxide semiconductor layer by a heat treatment;

forming a first channel protective layer over the first oxide semiconductor layer;

forming a second channel protective layer over the second oxide semiconductor layer;

forming a first source electrode and a first drain electrode over the first channel protective layer and the first oxide semiconductor layer;

forming a second source electrode and a second drain electrode over the second channel protective layer and the second oxide semiconductor layer; and

forming a pixel electrode electrically connected to the first oxide semiconductor layer,

wherein the first gate electrode, the gate insulating layer, the first oxide semiconductor layer, the first source electrode, the first drain electrode, the first channel protective layer, and the pixel electrode have a light-transmitting property.

11. The method for manufacturing a semiconductor device according to claim 10, further comprising:

forming a back-gate electrode over a second channel formation region of the second oxide semiconductor layer with the second channel protective layer interposed therebetween.

12. The method for manufacturing a semiconductor device according to claim 10,

wherein the first channel protective layer and the second channel protective layer comprise an oxide insulating film.

13. The method for manufacturing a semiconductor device according to claim 10,

wherein a first portion of the first oxide semiconductor layer is in contact with the first channel protective layer,

wherein a second portion of the first oxide semiconductor layer is not in contact with the first channel protective layer, and

wherein a carrier concentration of the second portion is more than a carrier concentration of the first portion.

14. The method for manufacturing a semiconductor device according to claim 10, further comprising:

performing a second heat treatment in an atmosphere including an inert gas, after forming the first channel protective layer and forming the second channel protective layer.

15. The method for manufacturing a semiconductor device according to claim 10,

wherein each of the first source electrode and the first drain electrode comprises a first conductive layer,

wherein each of the second source electrode and the second drain electrode comprises a second conductive layer and a third conductive layer over the second conductive layer,

wherein the first conductive layer and the second conductive layer comprise the same material having a light-transmitting property, and

wherein the third conductive layer comprises a metal.

16. The method for manufacturing a semiconductor device according to claim 10, wherein the second source electrode and the second drain electrode are formed of a film containing an element selected from the group consisting of Al, Cr, Cu, Ta, Ti, Mo, and W.

17. The method for manufacturing a semiconductor device according to claim 10, wherein the first source electrode, the first drain electrode, and the pixel electrode comprise any of indium oxide, an alloy of indium oxide and tin oxide, an alloy of indium oxide and zinc oxide, and zinc oxide.

18. A method for manufacturing a semiconductor device comprising:

forming a first gate electrode over a pixel portion of a substrate;

forming a second gate electrode over a driver circuit portion of the substrate;

forming a gate insulating layer over the first gate electrode and the second gate electrode;

forming a first oxide semiconductor layer and a second oxide semiconductor layer over the gate insulating layer;

performing dehydration or dehydrogenation of the first oxide semiconductor layer and the second oxide semiconductor layer by heat treatment;

forming a first channel protective layer over the first oxide semiconductor layer;

forming a second channel protective layer over the second oxide semiconductor layer;

forming a first source electrode and a first drain electrode over the first channel protective layer and the first oxide semiconductor layer; and

forming a second source electrode and a second drain electrode over the second channel protective layer and the second oxide semiconductor layer;

wherein the first gate electrode, the gate insulating layer, the first oxide semiconductor layer, the first source electrode, the first drain electrode, and the first channel protective layer have a light-transmitting property.

19. The method for manufacturing a semiconductor device according to claim 18, further comprising:

forming a back-gate electrode over a second channel formation region of the second oxide semiconductor layer with the second channel protective layer interposed therebetween.

20. The method for manufacturing a semiconductor device according to claim 18,

wherein the first channel protective layer and the second channel protective layer comprise an oxide insulating film.

21. The method for manufacturing a semiconductor device according to claim 18,

wherein a first portion of the first oxide semiconductor layer is in contact with the first channel protective layer,

wherein a second portion of the first oxide semiconductor layer is not in contact with the first channel protective layer, and

wherein a carrier concentration of the second portion is more than a carrier concentration of the first portion.

22. The method for manufacturing a semiconductor device according to claim 18, further comprising:

performing a second heat treatment in an atmosphere including an inert gas, after forming the first channel protective layer and forming the second channel protective layer.

23. The method for manufacturing a semiconductor device according to claim 18,

wherein each of the first source electrode and the first drain electrode comprises a first conductive layer,

wherein each of the second source electrode and the second drain electrode comprises a second conductive layer and a third conductive layer over the second conductive layer,

wherein the first conductive layer and the second conductive layer comprise the same material having a light-transmitting property, and

wherein the third conductive layer comprises a metal.

24. The method for manufacturing a semiconductor device according to claim 18, wherein the second source electrode and the second drain electrode are formed of a film containing an element selected from the group consisting of Al, Cr, Cu, Ta, Ti, Mo, and W.

25. The method for manufacturing a semiconductor device according to claim 18, wherein the first source electrode, and the first drain electrode comprise any of indium oxide, an alloy of indium oxide and tin oxide, an alloy of indium oxide and zinc oxide, and zinc oxide.