Substrate for semiconductor device, semiconductor device, and electronic apparatus

1. A substrate for a semiconductor device, comprising:

a base substrate;

a semiconductor layer that has a source region, a drain region, a plurality of channel regions, and at least one intermediate region, the plurality of channel regions being formed between the source region and the drain region, and the intermediate region being formed between the channel regions that are adjacent to each other or between each two of the plurality of channel regions that are adjacent to each other;

a source electrode that overlaps the source region in a plan view on or over the base substrate, the source electrode being in contact with the source region;

a drain electrode that overlaps the drain region in a plan view on or over the base substrate, the drain electrode being in contact with the drain region;

a gate electrode that overlaps the plurality of channel regions and the intermediate region and at least partially overlaps each of a part of the source electrode corresponding to the source region, the source electrode overlapping the source region at the part, and a part of the drain electrode corresponding to the drain region, the drain electrode overlapping the drain region at the part, in a plan view on or over the base substrate; and

a floating electrode that overlaps, or is formed at an area or each area substantially corresponding to, the intermediate region in a plan view on or over the base substrate, the floating electrode being in contact with the intermediate region, and the floating electrode being made of the same material as that of the source electrode and the drain electrode,

wherein, in an area where the semiconductor layer is formed on or over the base substrate, in a plan view, the size of an area where the floating electrode and the gate electrode overlap each other is smaller than the sum of the size of an area where the source electrode and the gate electrode overlap each other and the size of an area where the drain electrode and the gate electrode overlap each other.

2. The substrate for a semiconductor device according to claim 1 , wherein the source electrode, the drain electrode, and the floating electrode are formed in the same layer.

3. The substrate for a semiconductor device according to claim 1 , wherein the gate electrode is formed at a lower-layer-side position in a layered structure in comparison with the semiconductor layer; and each of the source electrode, the drain electrode, and the floating electrode is formed at an upper-layer-side position in the layered structure in comparison with the semiconductor layer.

4. The substrate for a semiconductor device according to claim 1 , wherein the gate electrode is formed at a lower-layer-side position in a layered structure in comparison with the semiconductor layer; and each of the source electrode, the drain electrode, and the floating electrode is formed at an upper-layer-side position in the layered structure in comparison with the gate electrode, which is a lower-layer-side position in the layered structure in comparison with the semiconductor layer.

5. The substrate for a semiconductor device according to claim 1 , wherein the gate electrode is formed at an upper-layer-side position in a layered structure in comparison with the semiconductor layer; and each of the source electrode, the drain electrode, and the floating electrode is formed at a lower-layer-side position in the layered structure in comparison with the semiconductor layer.

6. A semiconductor device that is provided with the substrate for a semiconductor device according to any of claims 1 to 5 .

7. An electronic apparatus that is provided with the semiconductor device according to claim 6 .