Electrostatic discharge circuit

1. An electrostatic discharge circuit, comprising:

a substrate;

an N+ buried layer in the substrate;

an n-type epitaxial layer on the N+ buried layer and the substrate;

a first P− region in an anode region of the n-type epitaxial layer;

a first N+ region in the first P− region;

an N-well in a cathode region of the n-type epitaxial layer;

a first P+ region in the N-well; and

a second N+ region located in the N-well,

the first N+ region being located closer to the second N+ region than the first P+ region.

2. The electrostatic discharge circuit of claim 1 , further comprising:

a second P− region; and

a first N− region in the N-well, the first P+ region being located in the second P− region, and the second N+ region being located in the first N− region.

3. The electrostatic discharge circuit of claim 1 , further comprising:

a second P+ region located in the first P− region, the second P+ region being at a left side of the first N+ region; and

a third P+ region located in the first P− region, the third P+ region being at a right side of the first N+ region.

4. The electrostatic discharge circuit of claim 1 , further comprising:

a first transistor including the first P+ region, the N-well, and the first P− region;

a second transistor including the N-well, the first P− region, and the first N+ region; and

a resistor of the N-well.

5. An electrostatic discharge circuit, comprising:

a substrate;

a buried layer of a first conductivity type included in the substrate;

an epitaxial layer on the buried layer of the first conductivity type and the substrate;

a well region of the first conductivity type included in a cathode region of the epitaxial layer;

a first lightly doped region of a second conductivity type and a second lightly doped region of the second conductivity type included in an anode region of the epitaxial layer and a portion of a region of the well region of the first conductivity type, the second conductivity type being opposite the first conductivity type;

a first lightly doped region of the first conductivity type included in the well region;

a first heavily doped region of the first conductivity type and a second heavily doped region of the first conductivity type included in a portion of the first lightly doped region of the second conductivity type and a portion of a region of the first lightly doped region of the first conductivity type, the second heavily doped region of the first conductivity type being located in the well region of the first conductivity type; and

a first heavily doped region of the second conductivity type included in a portion of a region of the second lightly doped region of the second conductivity type,

the first heavily doped region of the first conductivity type being located closer to the second heavily doped region of the first conductivity type than the first heavily doped region of the second conductivity type.

6. The electrostatic discharge circuit of claim 5 , further comprising:

a second heavily doped region of the second conductivity type included in a left region of the first heavily doped region of the first conductivity type in the first lightly doped region of the second conductivity type; and

a third heavily doped region of the second conductivity type included in a right region of the first heavily doped region of the first conductivity type in the first lightly doped region of the second conductivity type.

7. The electrostatic discharge circuit of claim 5 , further comprising:

a cathode electrode on each of the first heavily doped region of the second conductivity type and the second heavily doped region of the first conductivity type; and

an anode electrode on the first heavily doped region of the first conductivity type.

8. The electrostatic discharge circuit of claim 5 , wherein the buried layer includes high-concentration n type ions implanted into a first sub-region including all of the cathode and anode regions.

9. The electrostatic discharge circuit of claim 8 , further comprising:

a buried layer of the second conductivity type in a second sub-region on the substrate, a location of the second sub-region being different from a location of the first sub-region of the buried layer of the first conductivity type;

a well region of the second conductivity type included in the buried layer of the second conductivity type;

a third lightly doped region of the second conductivity type included in a portion of a region of the well region of the second conductivity type; and

a fourth heavily doped region of the second conductivity type included in a portion of a region of the third lightly doped region of the second conductivity type.

10. The electrostatic discharge circuit of claim 9 , wherein the buried layer of the second conductivity type includes high-concentration p type ions implanted into the second sub-region.

11. An electrostatic discharge circuit, comprising:

a substrate;

a buried layer of a first conductivity type in the substrate;

an epitaxial layer on the buried layer of the first conductivity type and the substrate;

a first lightly doped region of a second conductivity type in an anode region of the epitaxial layer, the second conductivity type being opposite the first conductivity type;

a first heavily doped region of the first conductivity type in the first lightly doped region of the second conductivity type;

an well region of the first conductivity type in a cathode region of the epitaxial layer;

a first heavily doped region of the second conductivity type in the well region of the first conductivity type; and

a second heavily doped region of the first conductivity type located in the well region of the first conductivity type,

the first heavily doped region of the first conductivity type being located closer to the second heavily doped region of the first conductivity type than the first heavily doped region of the second conductivity type.

12. The electrostatic discharge circuit of claim 11 , further comprising:

a second lightly doped region of the second conductivity type; and

a first lightly doped region of the first conductivity type in the well region of the first conductivity type, the first heavily doped region of the second conductivity type being located in the second lightly doped region of the second conductivity type, and the second heavily doped region of the first conductivity type being located in the first lightly doped region of the first conductivity type.

13. The electrostatic discharge circuit of claim 11 , further comprising:

a second heavily doped region of the second conductivity type located in the first lightly doped region of the second conductivity type, the second heavily doped region of the second conductivity type being at a left side of the first heavily doped region of the first conductivity type; and

a third heavily doped region of the second conductivity type located in the first lightly doped region of the second conductivity type, the third heavily doped region of the second conductivity type being at a right side of the first heavily doped region of the first conductivity type.

14. The electrostatic discharge circuit of claim 11 , wherein the first heavily doped region of the second conductivity type and the second heavily doped region of the first conductivity type are connected to a cathode terminal, and the first heavily doped region of the first conductivity type is connected to an anode terminal.

15. The electrostatic discharge circuit of claim 11 , further comprising:

a first transistor including the first heavily doped region of the second conductivity type, the well of the first conductivity type, and the first lightly doped region of the second conductivity type;

a second transistor including the well of the first conductivity type, the first lightly doped region of the second conductivity type, and the first heavily doped region of the first conductivity type; and

a resistor of the well region of the first conductivity type.

16. The electrostatic discharge circuit of claim 11 , further comprising:

a buried layer of the second conductivity type located in a sub-region on the substrate, the sub-region having a location different from a location of the buried layer of the first conductivity type;

a well of the second conductivity type on the buried layer of the second conductivity type in the epitaxial layer;

a third lightly doped region of the second conductivity type in the well region of the second conductivity type; and

a fourth heavily doped region of the second conductivity type in the third lightly doped region of the second conductivity type.

17. The electrostatic discharge circuit of claim 16 , further comprising:

a first transistor including the first heavily doped region of the second conductivity type, the well region of the first conductivity type, and the first lightly doped region of the second conductivity type;

a second transistor including the well region of the first conductivity type, the first lightly doped region of the second conductivity type, and the first heavily doped region of the first conductivity type;

a resistor of the well region of the first conductivity type; and

a third transistor including the first lightly doped region of the second conductivity type, the epitaxial layer, and the third lightly doped region of the second conductivity type.

18. The electrostatic discharge circuit of claim 16 , wherein the fourth heavily doped region of the second conductivity type is connected to the substrate.

19. The electrostatic discharge circuit of claim 11 , further comprising:

a second lightly doped region of the first conductivity type located in the epitaxial layer, the second lightly doped region of the first conductivity type being symmetrical to the well region of the first conductivity type with respect to the first lightly doped region of the second conductivity type; and

a third heavily doped region of the first conductivity type in the second lightly doped region of the first conductivity type.

20. The electrostatic discharge circuit of claim 19 , wherein the first heavily doped region of the second conductivity type, the second heavily doped region of the first conductivity type, and the third heavily doped region of the first conductivity type are connected to a cathode terminal, and the first heavily doped region of the first conductivity type is connected to an anode terminal.