Circuit board including a substrate with a recessed portion and manufacturing method thereof, electro-optical device and electronic apparatus

1. A circuit board comprising:

a substrate;

source and drain electrodes formed on the substrate;

an organic semiconductor layer formed on the source and drain electrodes;

a gate insulating layer formed on the organic semiconductor layer; and

a gate electrode formed on the gate insulating layer,

wherein the substrate includes a first part, a second part, and a third part interposed between the first and second parts and a thickness of the first part or a thickness of the second part is greater than that of the third part,

wherein the source electrode is formed on the first part,

wherein the drain electrode is formed on the second part,

wherein a part of the organic semiconductor layer is formed on the third part, and

wherein a thickness of the gate insulating layer disposed on the first and second parts is smaller than that of the gate insulating layer disposed on the third part and wherein the third part is defined by a trench formed in the substrate.

2. The circuit board of claim 1 , wherein a difference between a thickness of the first part or the second part and that of the third part is greater than a thickness of a part of the organic semiconductor layer which is formed on the third part.

3. A circuit board comprising:

a substrate;

a source electrode, a drain electrode, and a gate electrode disposed on one side of the substrate;

a gate insulating layer insulating the source electrode and the drain electrode from the gate electrode;

an organic semiconductor layer disposed to contact the gate insulating layer; and

a recessed portion, a bottom surface of which is disposed inside the substrate or on the substrate side disposed in a region between the source electrode and the drain electrode on which the organic semiconductor layer is formed, wherein a boundary surface between the organic semiconductor layer and the gate insulating layer is configured to be closer to a bottom surface of the substrate than boundary surfaces between the organic semiconductor layer and the gate insulating layer in other regions and wherein the recessed portion is defined by a trench in the substrate.

4. The circuit board of claim 3 , wherein a part of the organic semiconductor layer located in the region between the source electrode and the drain electrode is disposed inside the substrate.

5. The circuit board of claim 3 , wherein the recessed portion is formed in the region between the source electrode and the drain electrode.

6. The circuit board of claim 3 , wherein the recessed portion has a depth in the range 1 to 1000 nm.

7. The circuit board of claim 3 , wherein an average thickness of the organic semiconductor layer is equal to or smaller than a depth of the recessed portion.

8. The circuit board of claim 3 , wherein a boundary surface between the organic semiconductor layer and the gate insulating layer in a region between the source electrode and the drain electrode is configured to be the same distance from or closer to the bottom surface of the substrate as/than boundary surfaces between the source electrode and the substrate and between the drain electrode and the substrate.

9. The circuit board of claim 1 , wherein the substrate comprises:

a base body; and

a base insulating layer formed on the base body.

10. An electro-optical device comprising the circuit board of claim 1 .

11. An electronic apparatus comprising the electro-optical device of claim 10 .