Distributed reverse surge guard

• US 6,717,229 B2
• Filed: 03/11/2002
• Issued: 04/06/2004
• Est. Priority Date: 01/19/2000
• Status: Expired due to Term

• Current Assignee: Diodes Incorporated
• Original Assignee: FabTech, Inc. (Diodes Incorporated)
• Inventors: Smith, Wayne A., Hamerski, Roman J., Buchanan, Walter R.
• Primary Examiner(s): ECKERT II, GEORGE C
• Application Number:
  US10/096,203
• Publication Number:
  US 20020105044A1
• Time in Patent Office: 757 Days
• Field of Search: 257/471, 257/475, 257/476, 257/483, 257/484, 257/199, 257/481, 257/551, 257/603, 257/605
• US Class Current: 257/475
• CPC Class Codes: H01L 29/0619 with a supplementary region doped oppositely to or in rectifying contact with the semiconductor containing or contacting region, e.g. guard rings with PN or Schottky junction
• CPC Class Codes: H01L 29/872 Schottky diodes

Abstract

A diode (20), having first and second conductive layers (24,26), a conductive pad (28), and a distributed reverse surge guard (22), provides increased protection from reverse current surges. The surge guard (22) includes an outer loop (42) of P⁺-type surge guard material and an inner grid (44) of linear sections (46, 48) which form a plurality of inner loops extending inside the outer loop (42). The surge guard (22) distributes any reverse current over the area of the conductive pad (28) to provide increased protection from transient threats such as electrostatic discharge (ESD) and during electrical testing.

Claims

1. An electrical component having a distributed reverse surge guard, the component comprising:

a conductive pad including a primary conductive area having a primary conductive area edge;

a first region of surge guard material positioned adjacent the primary conductive area edge; and

a second region of surge guard material including a first side and a second side positioned adjacent the conductive pad and spaced from the primary conductive area edge with each of the first and second sides within the primary conductive area edge wherein a total operational guard area of the first region and the second region is less than approximately 25 percent of an operational conductive pad area, wherein the component has a forward voltage drop of less than approximately 900 mV where current density is approximately 175 A/cm².

2. The electrical component according to claim 1 further comprising a first conductive layer of a first conductive type, the first conductive layer being in electrical communication with the first and second regions and the conductive pad, and a second conductive layer of a second conductive type, the second conductive layer being in electrical communication with the first conductive layer.

3. The electrical component according to claim 2 wherein the first conductive layer comprises an epitaxial layer, and the second conductive layer comprises a substrate layer of monocrystalline semiconductor material.

4. The electrical component according to claim 2 wherein the first conductive type comprises an N⁻

type, the second conductive type comprises an N⁺ type, and the surge guard material comprises a p⁺ conductive type material.

5. The electrical component according to claim 4 wherein the p³⁰ conductive type material is diffused into the N⁻

type material.

6. The electrical component according to claim 1 wherein the conductive pad comprises a metallic pad having an edge margin, and the first region extends beyond the primary conductive area edge.

7. The electrical component according to claim 1 wherein the first region of surge guard material comprises a substantially continuous perimeter loop, and the second region is positioned within the perimeter loop.

8. The electrical component according to claim 7 wherein the second region comprises a grid of surge guard material forming a plurality of inner loops.

9. The electrical component according to claim 7 wherein the second region comprises a substantially linear region extending between substantially opposite sides of the perimeter loop.

10. An electrical component having a distributed reverse surge guard, the component comprising:

a conductive pad including a primary conductive area and a perimeter edge;

a first loop of surge guard material in physical contact and electrical communication with the conductive pad; and

a second loop of surge guard material in physical contact and electrical communication with the conductive pad wherein the component has a forward voltage drop of less than approximately 900 mV where current density is approximately 175 A/cm².

11. The electrical component according to claim 10 wherein the first and second loops comprise substantially continuous loops.

12. The electrical component according to claim 10 wherein the first loop extends adjacent the perimeter edge, and the second loop extends at least in part within the first loop.

13. The electrical component according to claim 12 further comprising a plurality of additional loops extending within the first loop.

14. The electrical component according to claim 13 wherein the second loop and the additional loops are substantially rectangular and substantially the same size.

15. The electrical component according to claim 10 wherein the first and second loops overlap in part.

16. A diode having a distributed reverse surge guard, the diode comprising:

a first conductive layer of a first conductive type;

a second conductive layer of a second conductive type, the second conductive layer being in electrical communication with the first conductive layer;

a conductive pad including a primary conductive area having a primary conductive area edge, the primary conductive area being in electrical communication with the first conductive layer;

a region of surge guard material including a first side and a second side positioned adjacent the conductive pad and spaced from the primary conductive area edge with each of the first and second sides within the primary conductive area edge wherein an operational area of the surge guard material is less than approximately 25 percent of an operational conductive pad area, wherein the component has a forward voltage drop of less than approximately 900 mV where current density is approximately 175 A/cm²; and

an electrical contact in electrical communication with the second conductive layer.

17. The diode according to claim 16 wherein the first conductive layer is juxtaposed the second conductive layer, the conductive pad is juxtaposed the first conductive layer, and the electrical contact is juxtaposed the second conductive layer.

18. The diode according to claim 16 wherein the first conductive type comprises an N⁻

type, the second conductive type comprises an N⁺ type, and the surge guard material comprises a P⁺ conductive type material.

19. The diode according to claim 16 further comprising another region of surge guard material positioned adjacent the primary conductive area edge, and the first region being in electrical communication with the first conductive layer and the primary conductive area.

20. The diode according to claim 19 wherein the region is joined with the other region.