Semiconductor device including dummy transistors with reduced off-leakage current

1. A semiconductor device, comprising:

an active region formed on a main surface of a semiconductor substrate and including a plurality of impurity regions of the same conductivity type arranged one-dimensionally; and

a plurality of gate electrodes, each of which is provided individually in each region between two adjacent impurity regions of said plurality of impurity regions when the main surface of said semiconductor substrate is seen in a plan view, and each of which forms an insulated gate field effect transistor together with the two adjacent impurity regions,

wherein said plurality of impurity regions include:

a first impurity region to which a predetermined voltage is applied,

second and third impurity regions forming a pair of conductive electrodes of an insulated gate field effect transistor,

fourth and fifth impurity regions, one of which forms a source electrode of a different insulated gate field effect transistor, and the other of which forms a drain electrode of the different insulated gate field effect transistor, and

at least one impurity region disposed between said first and fourth impurity regions,

wherein a voltage that causes electrical conduction between said second and third impurity regions is applied to a gate electrode, disposed between said second and third impurity regions, of said plurality of gate electrodes,

wherein a voltage that causes electrical conduction between said fourth and fifth impurity regions is applied to a gate electrode, disposed between said fourth and fifth impurity regions, of said plurality of gate electrodes,

wherein all gate electrodes disposed between said first and fourth impurity regions, of said plurality of gate electrodes, are configured to be electrically connected to said first impurity region constantly, and

wherein, by application of said predetermined voltage to all gate electrodes disposed between said first and fourth impurity regions, all impurity regions disposed between said first and fourth impurity regions, of said plurality of impurity regions, are electrically isolated from said first and fourth impurity regions and maintained in a floating state.

2. The semiconductor device according to claim 1 , further comprising:

a shallow trench isolation formed around said active region,

wherein said first impurity region is located at an end of one-dimensional arrangement formed by said plurality of impurity regions.

3. The semiconductor device according to claim 2 ,

wherein a length of said second impurity region along an arrangement direction of said plurality of impurity regions is equal to a length, along said arrangement direction, of each of all impurity regions disposed between said first and second impurity regions, and

lengths, along said arrangement direction, of all gate electrodes disposed between said first impurity region and said third impurity region when the main surface of said semiconductor substrate is seen in a plan view are equal to one another.

4. The semiconductor device according to claim 1 ,

wherein a length of said second impurity region along an arrangement direction of said plurality of impurity regions, a length of said fourth impurity region along said arrangement direction, and a length, along said arrangement direction, of each impurity region disposed between said second and fourth impurity regions and including said first impurity region are equal to one another, and

lengths, along said arrangement direction, of all gate electrodes disposed between said third and fifth impurity regions are equal to one another.

5. The semiconductor device according to claim 1 ,

wherein said second impurity region is connected to an insulated gate field effect transistor different from the insulated gate field effect transistor formed by said second and third impurity regions.

6. The semiconductor device according to claim 5 ,

wherein said plurality of impurity regions further include a fourth impurity region electrically connected to said second impurity region and forming one of a pair of conductive electrodes of said different insulated gate field effect transistor.

7. The semiconductor device according to claim 6 ,

wherein said third impurity region forms the other conductive electrode of said different insulated gate field effect transistor.

8. A semiconductor device, comprising:

an active region formed on a main surface of a semiconductor substrate and including a plurality of impurity regions of the same conductivity type arranged one-dimensionally;

a plurality of gate electrodes, each of which is provided individually in each region between two adjacent impurity regions of said plurality of impurity regions when the main surface of said semiconductor substrate is seen in a plan view, and each of which forms an insulated gate field effect transistor together with the two adjacent impurity regions; and

a different active region formed on the main surface of said semiconductor substrate, including a plurality of impurity regions of the same conductivity type arranged one-dimensionally, and isolated from said active region by a shallow trench isolation,

wherein said plurality of impurity regions include:

a first impurity region to which a predetermined voltage is applied,

second and third impurity regions forming a pair of conductive electrodes of an insulated gate field effect transistor, and

at least one impurity region disposed between said first and second impurity regions,

wherein a voltage that causes electrical conduction between said second and third impurity regions is applied to a gate electrode, disposed between said second and third impurity regions, of said plurality of gate electrodes,

wherein all gate electrodes disposed between said first and second impurity regions, of said plurality of gate electrodes, are configured to be electrically connected to said first impurity region constantly,

wherein by application of said predetermined voltage to all gate electrodes disposed between said first and second impurity regions, all impurity regions disposed between said first and second impurity regions, of said plurality of impurity regions, are electrically isolated from said first and second impurity regions and maintained in a floating state,

wherein said second impurity region is connected to an insulated gate field effect transistor different from the insulated gate field effect transistor formed by said second and third impurity regions, and

wherein said plurality of impurity regions of said different active region include a fourth impurity region electrically connected to said second impurity region and forming one of a pair of conductive electrodes of said different insulated gate field effect transistor.