High-voltage semiconductor device

1. A high-voltage semiconductor device comprising:

a first conductivity type semiconductor region formed on a dielectric layer; and

n transistors formed in the first conductivity type semiconductor region in series connection with one another, n being two or more, wherein;

a source electrode of a first stage transistor of the n transistors is connected to a low potential side of the semiconductor device and a drain electrode of a n-th stage transistor is connected to a high potential side of the semiconductor device;

the transistors nearer to the high potential side are surrounded by the transistors nearer to the low potential side; and

a gate terminal of the first stage transistor is a signal input terminal, and a drain terminal of the n-th transistor is a signal output terminal;

wherein each transistor of the n transistors comprises a source layer formed in a surface region of the semiconductor region in a ring shape, a drain layer formed in the surface region of the semiconductor region inside the source layer with a predetermined distance from the source layer, a source electrode in connection with the source layer, a drain electrode in connection with the drain layer, and a connection wiring that connects the drain electrode of a preceding stage transistor to the source electrode of a following stage transistor, and n resistance elements formed in series connection with one another between the drain electrode of the n-th stage transistor and the low potential side, a low potential side of each resistance element being connected to the gate electrode of each stage of transistor.

2. The high-voltage semiconductor device according to claim 1 , wherein a planar shape of a periphery of each transistor of the n transistors is a circle or an ellipse.

3. The high-voltage semiconductor device according to claim 1 , wherein the semiconductor region is formed on a support substrate interposing an embedded dielectric layer and partitioned by dielectric isolation from adjacent regions with trenches having a planar shape of a ring and containing buried dielectric substance; and

the dielectric layer is the embedded dielectric layer.

4. A high-voltage semiconductor device comprising:

a first conductivity type semiconductor region formed on a dielectric layer; and

n transistors formed in the first conductivity type semiconductor region in series connection with one another, n being two or more, wherein;

a source electrode of a first stage transistor of the n transistors is connected to a low potential side of the semiconductor device and a drain electrode of a n-th stage transistor is connected to a high potential side of the semiconductor device;

the transistors nearer to the high potential side are surrounded by the transistors nearer to the low potential side; and

a gate terminal of the first stage transistor is a signal input terminal, and a drain terminal of the n-th transistor is a signal output terminal;

wherein each stage of n transistors comprises:

a well diffusion layer of a second conductivity type formed in a ring shape in the semiconductor region;

a source layer of the first conductivity type selectively formed in a ring shape in a surface region of the well diffusion region;

a drain layer of the first conductivity type formed in the surface region of the semiconductor region inside the source layer with a predetermined distance from the source layer;

a gate electrode formed over a surface of the well diffusion layer between the semiconductor region and the source layer interposing a dielectric insulation film;

a source electrode in connection with the source layer and the well diffusion layer, and

a drain electrode in connection with the drain layer;

the high-voltage semiconductor device further comprising a connection wiring that connects the drain electrode of each of the first stage to (n−1)-th stage transistors to the source electrode of an adjacent inside transistor.

5. The high-voltage semiconductor device according to claim 4 , wherein a threshold voltage of the first stage transistor is higher than that of any other stages of transistor.

6. The high-voltage semiconductor device according to claim 4 , further comprising a drain pad in connection with the drain electrode of the n-th stage transistor.

7. The high-voltage semiconductor device according to claim 4 , further comprising n resistance elements formed in series connection with one another between the drain layer of the n-th stage transistor and the low potential side, a low potential side of the each stage of resistance element being in connection with the gate electrode of the stage of transistor.

8. The high-voltage semiconductor device according to claim 4 , wherein the well diffusion layer of at least one of the n transistors reaches the embedded dielectric layer.

9. The high-voltage semiconductor device according to claim 6 , further comprising a floating reference gate drive circuit region surrounded by a trench reaching the embedded base region different from the tranches, in another region of the semiconductor region of the semiconductor layer, and an electrode pad formed on the floating reference gate drive circuit region, the electrode pad being connected to the drain pad with a bonding wire.

10. The high-voltage semiconductor device according to claim 4 , wherein the semiconductor region is formed on a support substrate interposing an embedded dielectric layer and partitioned by dielectric isolation from adjacent regions with trenches having a planar shape of a ring and containing buried dielectric substance; and

the dielectric layer is the embedded dielectric layer.