Isolation structure for semiconductor device having self-biasing buried layer and method therefor
A semiconductor device includes a floating buried doped region, a first doped region disposed between the floating buried doped region and a first major surface, and a semiconductor region disposed between the floating buried doped region and a second major surface. A trench isolation structure extends from the first major surface and terminates within the semiconductor region and the floating buried doped region abuts the trench isolation structure. A second doped region is disposed in the first doped region has an opposite conductivity type to the first doped region. A first isolation device is disposed in the first doped region and is configured to divert current injected into the semiconductor device from other regions thereby delaying the triggering of an internal SCR structure. In one embodiment, a second isolation structure is disposed within the first doped region and is configured to disrupt a leakage path along a sidewall surface of the trench isolation structure.
1. A semiconductor device structure comprising:
a self-isolating bulk semiconductor substrate having first and second opposing major surfaces, wherein the self-isolating bulk semiconductor substrate includes:
a floating buried doped region of a first conductivity type;
a first doped region of a second conductivity type opposite to the first conductivity type disposed between the floating buried doped region and the first major surface, wherein the first doped region abuts the floating buried doped region; and
a semiconductor region of the second conductivity type disposed between the floating buried doped region and the second major surface;
a trench isolation structure extending from the first major surface through the first doped region, extending through the floating buried doped region, and extending into the semiconductor region, wherein the floating buried doped region abuts the trench isolation structure;
a second doped region of the first conductivity type within the first doped region; and
a first isolation device disposed in the first doped region between the second doped region and the trench isolation structure, the first isolation device comprising:
a first isolation first doped region of the first conductivity type; and
a first isolation second doped region of the second conductivity type disposed between the second doped region and the first isolation first doped region, wherein the first isolation first doped region is electrically shorted to the first isolation second doped region.
2. The structure of claim 1 , wherein the first isolation device further comprises a first isolation third doped region of the second conductivity type disposed between the first isolation first doped region and the trench isolation structure.
3. The structure of claim 2 , wherein the first isolation third doped region is electrically shorted to the first isolation first doped region and the first isolation second doped region.
4. The structure of claim 2 , wherein:
the trench isolation structure comprises a conductive material separated from the self-isolating bulk semiconductor substrate by a dielectric material; and
the structure further comprises a second isolation device disposed between the first isolation device and the trench isolation structure, the second isolation device comprising a second isolation first doped region of the second conductivity type.
5. The structure of claim 4 , wherein the second isolation first doped region extends to greater depth into the first doped region than the first isolation second doped region and the first isolation third doped region.
6. The structure of claim 4 , wherein the second isolation first doped region abuts a side surface of the trench isolation structure.
7. The structure of claim 4 , wherein the second isolation first doped region is laterally spaced apart from a side surface of the trench isolation structure.
8. The structure of claim 4 , wherein the first isolation third doped region laterally overlaps at least a portion of the second isolation first doped region.
9. The structure of claim 4 , wherein the second isolation first doped region, the first isolation first doped region, the first isolation second doped region, and the first isolation third doped region are electrically shorted together.
10. The structure of claim 4 , wherein the second isolation first doped region is electrically floating.
11. The structure of claim 1 further comprising a second isolation device, the second isolation device comprising a second isolation first doped region of the second conductivity type disposed between the first isolation device and the trench isolation structure, wherein the second isolation first doped region extends to a greater depth into the first doped region than the first isolation first doped region and the first isolation second doped region.
12. The structure of claim 1 , wherein the floating buried doped region comprises:
a first region adjoining the first doped region;
a second region disposed between the first region and the semiconductor region, wherein the first region has a lower dopant concentration than the second region; and
a third region disposed between the second region and the semiconductor region, wherein the third region has a lower dopant concentration than the second region.
13. A semiconductor device structure comprising:
a self-isolating bulk semiconductor substrate having first and second opposing major surfaces, wherein the self-isolating bulk semiconductor substrate includes:
a floating buried doped region of a first conductivity type;
a first doped region of a second conductivity type opposite to the first conductivity type disposed between the floating buried doped region and the first major surface, wherein the first doped region abuts the floating buried doped region; and
a semiconductor region of the second conductivity type disposed between the floating buried doped region and the second major surface;
a trench isolation structure extending from the first major surface through the first doped region, extending through the floating buried doped region, and extending into the semiconductor region, wherein the floating buried doped region abuts the trench isolation structure;
a second doped region of the first conductivity type within the first doped region; and
a first isolation device disposed in the first doped region between the second doped region and the trench isolation structure, the first isolation device comprising:
a first isolation first doped region of the first conductivity type;
a first isolation second doped region of the second conductivity type disposed between the second doped region and the first isolation first doped region; and
a first isolation third doped region of the second conductivity type disposed between the first isolation first doped region and the trench isolation structure, wherein the first isolation first doped region is electrically shorted to the first isolation second doped region.
14. The structure of claim 13 , wherein:
the trench isolation structure comprises a conductive material separated from the self-isolating bulk semiconductor substrate by a dielectric material; and
the structure further comprises a second isolation device disposed between the first isolation device and the trench isolation structure, the second isolation device comprising a second isolation first doped region of the second conductivity type.
15. The structure of claim 14 , wherein the first isolation third doped region is electrically shorted to the first isolation first doped region and the first isolation second doped region.
16. The structure of claim 15 , wherein the first isolation third doped region laterally overlaps at least a portion of the second isolation first doped region.
17. A method of forming semiconductor device structure comprising:
providing a self-isolating bulk semiconductor substrate having first and second opposing major surfaces, wherein the self-isolating bulk semiconductor substrate includes:
a floating buried doped region of a first conductivity type;
a first doped region of a second conductivity type opposite to the first conductivity type disposed between the floating buried doped region and the first major surface, wherein the first doped region abuts the floating buried doped region; and
a semiconductor region of the second conductivity type disposed between the floating buried doped region and the second major surface;
providing a trench isolation structure extending from the first major surface through the first doped region, extending through the floating buried doped region, and extending into the semiconductor region, wherein the floating buried doped region abuts the trench isolation structure;
providing a second doped region of the first conductivity type within the first doped region; and
providing a first isolation device disposed in the first doped region between the second doped region and the trench isolation structure, the first isolation device comprising:
a first isolation first doped region of the first conductivity type;
a first isolation second doped region of the second conductivity type disposed between the second doped region and the first isolation first doped region; and
a first isolation third doped region of the second conductivity type disposed between the first isolation first doped region and the trench isolation structure, wherein the first isolation first doped region is electrically shorted to the first isolation second doped region.
18. The method of claim 17 , wherein:
providing the trench isolation structure comprises a providing the trench isolation structure comprising a conductive material separated from the self-isolating bulk semiconductor substrate by a dielectric material; and
the method further comprises providing a second isolation device disposed between the first isolation device and the trench isolation structure, the second isolation device comprising a second isolation first doped region of the second conductivity type.
19. The method of claim 18 , wherein providing the first isolation third doped region comprises providing the first isolation third doped region electrically shorted to the first isolation first doped region and the first isolation second doped region.
20. The method of claim 18 , wherein providing the first isolation third doped region comprises providing the first isolation third doped region laterally overlapping at least a portion of the second isolation first doped region.