Display device, manufacturing method thereof, and electrode forming method

1. A display device comprising:

a substrate;

first and second transistors provided on the substrate to be spaced apart from each other, the first and second transistors being electrically connected to each other; and

a display unit electrically connected to the first transistor, wherein

the first transistor includes a first semiconductor layer including crystalline silicon, a first gate electrode, a first source electrode, and a first drain electrode,

the second transistor includes a second semiconductor layer including an oxide semiconductor, a second gate electrode, a second source electrode, and a second drain electrode, and

each of the second source electrode and the second drain electrode includes a first layer that includes molybdenum and is provided on the second semiconductor layer, a second layer that includes aluminum and is provided on the first layer, a side layer containing aluminum oxide (Al x O y ) is provided on a side part of the second layer, and a third layer that includes titanium and is provided on the second layer, wherein end surfaces of a side part of the first layer, the side layer containing aluminum oxide and a side part of the third layer are coplanar.

2. The display device of claim 1 , further comprising:

a first insulating layer provided between the first semiconductor layer and the first gate electrode;

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

a capacitor electrode provided on the second insulating layer, the capacitor electrode overlapping with the first gate electrode.

3. The display device of claim 1 , further comprising a third insulating layer provided between the second semiconductor layer and the second gate electrode, wherein

the second source electrode and the second drain electrode are provided on the third insulating layer.

4. The display device of claim 3 , wherein:

the first source electrode and the first drain electrode are provided on the third insulating layer, and

each of the first source electrode and the first drain electrode includes a first layer provided on the third insulating layer, a second layer provided on the first layer, and a third layer provided on the second layer.

5. The display device of claim 1 , wherein the display unit includes:

a first electrode electrically connected to the first drain electrode;

a second electrode provided on the first electrode; and

an emitting layer provided between the first electrode and the second electrode.

6. The display device of claim 1 , wherein the first transistor is a driving transistor, and the second transistor is a switching transistor.

7. The display device of claim 1 , wherein:

each of the second source electrode and the second drain electrode makes contact with a respective side surface of the second semiconductor layer, and

a first thickness of each of the second source electrode and the second drain electrode at a distil end above the second semiconductor layer is thinner than a thickness of each of the second source electrode and the second drain electrode at a distil end not above the second semiconductor layer.

8. The display device of claim 1 , wherein the second layer of each of the second source electrode and the second drain electrode is pure aluminum or an aluminum alloy.