Semiconductor integrated circuit and system LSI including the same

• US 20070252231A1
• Filed: 04/06/2007
• Published: 11/01/2007
• Est. Priority Date: 04/27/2006
• Status: Active Grant

• Current Assignee: Socionext Inc.
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Usami, Shiro
• Granted Patent: US 7,821,096 B2
• Time in Patent Office: Days
• US Class Current: 257/499
• CPC Class Codes: H01L 29/417 carrying the current to be rectified, amplified or switched
• CPC Class Codes: H01L 29/8611 Planar PN junction diodes

Abstract

A semiconductor integrated circuit having a diode element includes a diffusion layer which constitutes the anode and two diffusion layers which are provided on the left and right sides of the anode and which constitute the cathode, such that the anode and the cathode constitute the diode. A well contact is provided to surround both the diffusion layers of the anode and cathode. Distance tS between a longer side of the well contact and the diffusion layers of the cathode is shorter, while distance tL between a shorter side of the well contact and the diffusion layers of the anode and cathode is longer (tL>tS). Accordingly, the resistance value between the diffusion layer of the anode and the shorter side of the well contact is larger, so that the current from the diffusion layer of the anode is unlikely to flow toward the shorter side of the well contact. Thus, convergence of the current at the contact holes of the diffusion layer of the anode is reduced, so that the reliability of the diode element improves.

Claims

1. A semiconductor integrated circuit, comprising:

a diode including a first polarity-type diffusion layer which constitutes an anode of the diode and a second polarity-type diffusion layer which is in the vicinity of the first polarity-type diffusion layer and which constitutes a cathode of the diode; and

a second polarity-type substrate or well contact provided around the diode,

wherein each of the first polarity-type diffusion layer and second polarity-type diffusion layer of the diode and the substrate or well contact has a plurality of contact holes for electrical connection with an external device,

a positioning pitch of the plurality of contact holes of the second polarity-type substrate or well contact is greater than a positioning pitch of the plurality of contact holes of the first polarity-type diffusion layer which constitutes the anode of the diode.

16. The semiconductor integrated circuit of claim 1, wherein the first polarity-type diffusion layer which constitutes the anode of the diode and the second polarity-type diffusion layer which constitutes the cathode of the diode have the shape of a rectangular strip.

22. The semiconductor integrated circuit of claim 16, wherein the second polarity-type diffusion layer which constitutes the cathode of the diode is provided on both left and right sides of the first polarity-type diffusion layer which constitutes the anode of the diode.

23. A system LSI, comprising:

a digital circuit and an analog circuit which operate on separate power supplies; and

a single unit of protection device formed by two semiconductor integrated circuits of claim 1 and provided between the digital circuit and the analog circuit for allowing electrostatic discharge from the digital circuit to the analog circuit and electrostatic discharge from the analog circuit to the digital circuit.

2. A semiconductor integrated circuit, comprising:

a diode including a first polarity-type diffusion layer which constitutes an anode of the diode and a second polarity-type diffusion layer which faces the first polarity-type diffusion layer and which constitutes a cathode of the diode; and

a second polarity-type substrate or well contact surrounding four sides of the diode,

wherein each of the first polarity-type diffusion layer and second polarity-type diffusion layer of the diode has a plurality of contact holes for electrical connection with an external device, and

the substrate or well contact has a plurality of contact holes except for a portion extending parallel to a direction in which the first polarity-type diffusion layer and the second polarity-type diffusion layer face each other.

3. The semiconductor integrated circuit of claim 2, wherein the substrate or well contact has the plurality of contact holes only in a portion extending perpendicular to the direction in which the first polarity-type diffusion layer and the second polarity-type diffusion layer face each other.

17. The semiconductor integrated circuit of claim 2, wherein the first polarity-type diffusion layer which constitutes the anode of the diode and the second polarity-type diffusion layer which constitutes the cathode of the diode have the shape of a rectangular strip.

24. A system LSI, comprising:

a digital circuit and an analog circuit which operate on separate power supplies; and

a single unit of protection device formed by two semiconductor integrated circuits of claim 2 and provided between the digital circuit and the analog circuit for allowing electrostatic discharge from the digital circuit to the analog circuit and electrostatic discharge from the analog circuit to the digital circuit.

4. A semiconductor integrated circuit, comprising:

a diode including a first polarity-type diffusion layer which constitutes an anode of the diode and a second polarity-type diffusion layer which faces the first polarity-type diffusion layer and which constitutes a cathode of the diode; and

a second polarity-type substrate or well contact formed only by a portion extending perpendicular to a direction in which the first polarity-type diffusion layer and the second polarity-type diffusion layer face each other,

wherein each of the first polarity-type diffusion layer and second polarity-type diffusion layer of the diode and the substrate or well contact has a plurality of contact holes for electrical connection with an external device.

18. The semiconductor integrated circuit of claim 4, wherein the first polarity-type diffusion layer which constitutes the anode of the diode and the second polarity-type diffusion layer which constitutes the cathode of the diode have the shape of a rectangular strip.

25. A system LSI, comprising:

a digital circuit and an analog circuit which operate on separate power supplies; and

a single unit of protection device formed by two semiconductor integrated circuits r of claim 4 and provided between the digital circuit and the analog circuit for allowing electrostatic discharge from the digital circuit to the analog circuit and electrostatic discharge from the analog circuit to the digital circuit.

5. A semiconductor integrated circuit, comprising:

a diode including a first polarity-type diffusion layer which constitutes an anode of the diode and a second polarity-type diffusion layer which faces the first polarity-type diffusion layer and which constitutes a cathode of the diode; and

a second polarity-type substrate or well contact surrounding four sides of the diode,

wherein each of the first polarity-type diffusion layer and second polarity-type diffusion layer of the diode and the substrate or well contact has a plurality of contact holes for electrical connection with an external device,

a portion of the substrate or well contact extending parallel a direction in which the first polarity-type diffusion layer and the second polarity-type diffusion layer face each other has a greater separation from the first polarity-type diffusion layer or second polarity-type diffusion layer of the diode than a portion of the substrate or well contact extending perpendicular to the facing direction of the diffusion layers.

6. The semiconductor integrated circuit of claim 5, wherein a positioning pitch of the plurality of contact holes of the second polarity-type substrate or well contact is greater than a positioning pitch of the plurality of contact holes of the first polarity-type diffusion layer which constitutes the anode of the diode.

7. The semiconductor integrated circuit of claim 5, wherein the substrate or well contact has the plurality of contact holes except for a portion extending parallel to the direction in which the first polarity-type diffusion layer and the second polarity-type diffusion layer face each other.

8. The semiconductor integrated circuit of claim 5, wherein the substrate or well contact has the plurality of contact holes only in a portion extending perpendicular to the direction in which the first polarity-type diffusion layer and the second polarity-type diffusion layer face each other.

19. The semiconductor integrated circuit of claim 5, wherein the first polarity-type diffusion layer which constitutes the anode of the diode and the second polarity-type diffusion layer which constitutes the cathode of the diode have the shape of a rectangular strip.

26. A system LSI, comprising:

a digital circuit and an analog circuit which operate on separate power supplies; and

a single unit of protection device formed by two semiconductor integrated circuits of claim 5 and provided between the digital circuit and the analog circuit for allowing electrostatic discharge from the digital circuit to the analog circuit and electrostatic discharge from the analog circuit to the digital circuit.

9. A semiconductor integrated circuit, comprising:

a diode including a first polarity-type diffusion layer which constitutes an anode of the diode and a second polarity-type diffusion layer which faces the first polarity-type diffusion layer and which constitutes a cathode of the diode; and

a second polarity-type substrate or well contact which shares a diffusion layer with the second polarity-type diffusion layer constituting the cathode of the diode and which surrounds four sides of the diode,

wherein each of the first polarity-type diffusion layer and second polarity-type diffusion layer of the diode and the substrate or well contact has a plurality of contact holes for electrical connection with an external device, and

a portion of the substrate or well contact extending parallel to a direction in which the first polarity-type diffusion layer and the second polarity-type diffusion layer face each other has a greater separation from the first polarity-type diffusion layer or second polarity-type diffusion layer of the diode than a portion of the substrate or well contact extending perpendicular to the facing direction of the diffusion layers.

10. The semiconductor integrated circuit of claim 9, wherein a positioning pitch of the plurality of contact holes of the second polarity-type substrate or well contact is greater than a positioning pitch of the plurality of contact holes of the first polarity-type diffusion layer which constitutes the anode of the diode.

11. The semiconductor integrated circuit of claim 9, wherein the substrate or well contact has the plurality of contact holes except for a portion extending parallel to the direction in which the first polarity-type diffusion layer and the second polarity-type diffusion layer face each other.

12. The semiconductor integrated circuit of claim 9, wherein the substrate or well contact has the plurality of contact holes only in a portion extending perpendicular to the direction in which the first polarity-type diffusion layer and the second polarity-type diffusion layer face each other.

13. The semiconductor integrated circuit of claim 9, wherein the number of contact holes formed in the first polarity-type diffusion layer which constitutes the anode of the diode is equal to the number of contact holes formed in the second polarity-type diffusion layer which shares a diffusion layer with the second polarity-type substrate or well contact and which constitutes the cathode of the diode.

20. The semiconductor integrated circuit of claim 9, wherein the first polarity-type diffusion layer which constitutes the anode of the diode and the second polarity-type diffusion layer which constitutes the cathode of the diode have the shape of a rectangular strip.

27. A system LSI, comprising:

a digital circuit and an analog circuit which operate on separate power supplies; and

a single unit of protection device formed by two semiconductor integrated circuits of claim 9 and provided between the digital circuit and the analog circuit for allowing electrostatic discharge from the digital circuit to the analog circuit and electrostatic discharge from the analog circuit to the digital circuit.

14. A semiconductor integrated circuit, comprising:

a diode including a first polarity-type diffusion layer which constitutes an anode of the diode and a second polarity-type diffusion layer which is in the vicinity of the first polarity-type diffusion layer and which constitutes a cathode of the diode; and

a second polarity-type substrate or well contact,

wherein the second polarity-type diffusion layer which constitutes the cathode of the diode substitutes for the second polarity-type substrate or well contact.

15. The semiconductor integrated circuit of claim 14, wherein:

each of the first polarity-type diffusion layer of the diode and the second polarity-type diffusion layer of the diode which substitutes for the substrate or well contact has a plurality of contact holes for electrical connection with an external device, and

the number of contact holes formed in the first polarity-type diffusion layer of the diode is equal to the number of contact holes formed in the second polarity-type diffusion layer of the diode which substitutes for the substrate or well contact.

21. The semiconductor integrated circuit of claim 14, wherein the first polarity-type diffusion layer which constitutes the anode of the diode and the second polarity-type diffusion layer which constitutes the cathode of the diode have the shape of a rectangular strip.

28. A system LSI, comprising:

a digital circuit and an analog circuit which operate on separate power supplies; and

a single unit of protection device formed by two semiconductor integrated circuits of claim 14 and provided between the digital circuit and the analog circuit for allowing electrostatic discharge from the digital circuit to the analog circuit and electrostatic discharge from the analog circuit to the digital circuit.