Semiconductor device having electrode pad, and wireless circuit device including the semiconductor device

1. A semiconductor device comprising:

a layered region formed in a semiconductor substrate of a first conductivity type;

an electrode pad formed on the semiconductor substrate with an interlayer insulating film interposed therebetween and placed above the layered region; and

a conductive film formed in the semiconductor substrate and surrounding a periphery of the layered region, wherein

the layered region includes:

a first impurity diffusion region;

a second impurity diffusion region formed on the first impurity diffusion region; and

a third impurity diffusion region formed on the first impurity diffusion region and surrounding a periphery of the second impurity diffusion region,

a conductivity type of the first impurity diffusion region and a conductivity type of the third impurity diffusion region are a second conductivity type,

a conductivity type of the second impurity diffusion region is the first conductivity type,

an impurity concentration of the third impurity diffusion region is higher than an impurity concentration of the first impurity diffusion region, and

the third impurity diffusion region is electrically connected to a terminal fixed to a constant potential.

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

a wire formed in the interlayer insulating film and electrically connected to the terminal, wherein

the third impurity diffusion region is electrically connected to the wire, and

the wire is placed in an area outside a formation area of the electrode pad.

3. A semiconductor device comprising:

a layered region formed in a semiconductor substrate of a first conductivity type;

an electrode pad formed on the semiconductor substrate with an interlayer insulating film interposed therebetween and placed above the layered region; and

an insulating film formed in the semiconductor substrate and surrounding a periphery of the layered region, wherein

the layered region includes:

a first impurity diffusion region;

a second impurity diffusion region formed on the first impurity diffusion region; and

a third impurity diffusion region formed on the first impurity diffusion region and surrounding a periphery of the second impurity diffusion region,

a conductivity type of the first impurity diffusion region and a conductivity type of the third impurity diffusion region are a second conductivity type,

a conductivity type of the second impurity diffusion region is the first conductivity type,

an impurity concentration of the third impurity diffusion region is higher than an impurity concentration of the first impurity diffusion region, and

the third impurity diffusion region is electrically connected to a terminal fixed to a constant potential.

4. The semiconductor device of claim 1 , wherein

the conductive film is electrically connected to a conductive film terminal fixed to a constant potential.

5. The semiconductor device of claim 4 , further comprising:

a wire formed in the interlayer insulating film and electrically connected to the conductive film terminal, wherein

the conductive film is electrically connected to the wire, and

the wire is placed in an area outside a formation area of the electrode pad.

6. The semiconductor device of claim 4 , wherein

a potential of the third impurity diffusion region is a first potential, and

a potential of the conductive film is a second potential different from the first potential.

7. The semiconductor device of claim 6 , further comprising:

detection means for detecting a noise signal leaking from the conductive film;

control means for controlling a potential of the third impurity diffusion region to be at the first potential based on the noise signal detected by the detection means; and

control means for controlling a potential of the conductive film to be at the second potential based on the noise signal detected by the detection means.

8. The semiconductor device of claim 1 , wherein

the electrode pad is an input electrode pad or an output electrode pad.

9. The semiconductor device of claim 1 , further comprising:

a digital switch circuit; and

an attenuation circuit, wherein

the attenuation circuit is connected downstream of the digital switch circuit, and

the electrode pad is connected downstream of the attenuation circuit.

10. The semiconductor device of claim 1 , further comprising:

a digital switch circuit; and

an amplification circuit, wherein

the amplification circuit is connected downstream of the digital switch circuit, and

the electrode pad is connected downstream of the amplification circuit.

11. A wireless circuit device comprising:

the semiconductor device of claim 9 ;

an amplifier connected to the semiconductor device and receiving a signal from the electrode pad; and

an antenna connected to the amplifier and transmitting to outside a signal from the amplifier in the form of a radio wave.

12. A wireless circuit device comprising:

the semiconductor device of claim 10 ;

an amplifier connected to the semiconductor device and receiving a signal from the electrode pad; and

an antenna connected to the amplifier and transmitting to outside a signal from the amplifier in the form of a radio wave.

13. The semiconductor device of claim 3 , wherein

the electrode pad is an input electrode pad or an output electrode pad.

14. The semiconductor device of claim 3 , further comprising:

a digital switch circuit; and

an attenuation circuit, wherein

the attenuation circuit is connected downstream of the digital switch circuit, and

the electrode pad is connected downstream of the attenuation circuit.

15. The semiconductor device of claim 3 , further comprising:

a digital switch circuit; and

an amplification circuit, wherein

the amplification circuit is connected downstream of the digital switch circuit, and

the electrode pad is connected downstream of the amplification circuit.

16. A wireless circuit device comprising:

the semiconductor device of claim 14 ;

an amplifier connected to the semiconductor device and receiving a signal from the electrode pad; and

an antenna connected to the amplifier and transmitting to outside a signal from the amplifier in the form of a radio wave.

17. A wireless circuit device comprising:

the semiconductor device of claim 15 ;

an amplifier connected to the semiconductor device and receiving a signal from the electrode pad; and

an antenna connected to the amplifier and transmitting to outside a signal from the amplifier in the form of a radio wave.