Integrated circuit ESD protection
View Patent ↗A protective device in a semiconductor may comprise a substrate of a first conductivity type, an epitaxial layer formed on top of the substrate, a body area formed within the epitaxial layer of a second conductivity type extending from a top surface into the epitaxial layer, a first area of the first conductivity type extending from the top surface into the body area, an isolation area surrounding the first area, a ring area of the first conductivity type surrounding the isolation area, and a coupling structure for connecting the ring area with the substrate.
1. A protective device in a semiconductor comprising:
a substrate of a first conductivity type,
an epitaxial layer formed on top of said substrate,
a body area of a second conductivity type formed within said epitaxial layer and extending from a top surface into said epitaxial layer,
a first area of the first conductivity type extending from said top surface into said body area,
an isolation area surrounding said first area,
a ring area of the first conductivity type surrounding said isolation area,
a coupling structure for electrically connecting said ring area with said substrate.
2. A protective device according to claim 1 , further comprising
a first intermediate ring area of said first conductivity type arranged between said first area and said isolation area, and
a second intermediate ring area of said first conductivity type arranged between said isolation area and said ring area.
3. A protective device according to claim 2 , wherein the first and second intermediate areas are less doped than the first area.
4. A protective device according to claim 2 , wherein said first area and said ring area extend from said top surface deeper into said epitaxial layer than said first and second intermediate areas.
5. A protective device according to claim 1 , wherein said isolation area is formed by local oxidation of silicon or other isolation methods.
6. A protective device according to claim 1 , wherein said body area extends to a top surface of said substrate.
7. A protective device according to claim 1 , wherein said body area is embedded into said epitaxial layer in such a way that the epitaxial layer surrounds said body area with a cup-shaped form.
8. A protective device according to claim 1 , wherein said first area has a circular, square, octagonal, or polygonal shape.
9. A protective device according to claim 1 , wherein said isolation area and said ring area have a circular, square, octagonal, or polygonal shape.
10. A protective device according to claim 1 , wherein said coupling structure is a sinker of said first conductivity type.
11. A protective device according to claim 10 , wherein said sinker is adjacent to said ring area and reaches from said top surface to the substrate.
12. A protective device according to claim 10 , wherein said sinker is arranged below said ring area and reaches from a bottom of said ring area to the substrate.
13. A protective device according to claim 1 , wherein said coupling structure is a trench structure filled with a conductive material.
14. A protective device according to claim 13 , further comprising metal barrier layers between said trench structure and said ring area and said substrate, respectively.
15. A protective device according to claim 1 , further comprising an LDMOS transistor having a gate, wherein said gate is electrically connected with said first area.
16. A protective device according to claim 15 , wherein said LDMOS transistor comprises a source zone being adjacent and connected to said coupling structure.
17. A protective device in a semiconductor comprising:
a substrate of a first conductivity type,
an epitaxial layer formed on top of said substrate,
a body area of a second conductivity type formed within said epitaxial layer and extending from a top surface into said epitaxial layer,
a first area of the first conductivity type extending from said top surface into said body area,
a first ring area of the first conductivity type surrounding said first area,
an isolation area surrounding said first ring area,
a second ring area of the first conductivity type surrounding said isolation area,
a third ring area of the first conductivity type surrounding said second ring area,
a coupling structure for connecting said third ring area with said substrate.
18. A protective device according to claim 17 , wherein the first and second ring areas are less doped than the first area.
19. A protective device according to claim 17 , wherein said first area and said third ring area extend from said top surface deeper into said epitaxial layer than said first and second ring areas.
20. A protective device according to claim 17 , wherein said isolation area is formed by local oxidation of silicon or other isolation methods.
21. A protective device according to claim 17 , wherein said body area extends to a top surface of said substrate.
22. A protective device according to claim 17 , wherein said first area has a circular, square, octagonal, or polygonal shape.
23. A protective device according to claim 17 , wherein said isolation area and said first and second ring area have a circular, square, octagonal, or polygonal shape.
24. A protective device according to claim 17 , wherein said coupling structure is a sinker of said first conductivity type.
25. A protective device according to claim 24 , wherein said sinker is adjacent to said third ring area and reaches from said top surface to the substrate.
26. A protective device according to claim 24 , wherein said sinker is arranged below said third ring area and reaches from a bottom of said third ring area to the substrate.