Bi-directional bipolar junction transistor for high voltage electrostatic discharge protection
A bi-directional electrostatic discharge (ESD) protection device may include a substrate, an N+ doped buried layer, an N-type well region and two P-type well regions. The N+ doped buried layer may be disposed proximate to the substrate. The N-type well region may encompass the two P-type well regions such that a portion of the N-type well region is interposed between the two P-type well regions. The P-type well regions may be disposed proximate to the N+ doped buried layer and comprise one or more N+ doped plates, one or more P+ doped plates, one or more field oxide (FOX) portions, and one or more field plates. A multi-emitter structure is also provided.
1. A bi-directional bipolar junction transistor (BJT) comprising:
a p-type substrate;
an N+ doped buried layer disposed adjacent to the substrate;
a first P-type well region disposed adjacent to the N+ doped buried layer, wherein the first p-type well region is in contact with the N+ doped buried layer;
a second P-type well region disposed adjacent to the N+ doped buried layer, wherein the second p-type well region is in contact with the N+ doped buried layer;
an N-type well region adjacent to the N+ doped buried layer and encompassing the first and second P-type well regions such that at least a portion of the N-type well region is interposed between the first and second P-type well regions;
first, second, and third field oxide (FOX) portions disposed adjacent to the N-type well region; and
first, second, third, and fourth field plates, the first field plate being disposed adjacent to the first FOX portion, the second and third field plates being disposed adjacent to respective portions of the second FOX portion, and the fourth field plate being disposed adjacent to third FOX portion;
wherein the first and second P-type wells each comprise at least one N+ doped plate and at least one P+ doped plate.
2. The bi-directional BJT of claim 1 , wherein the first P-type well comprises first and second N+ doped plates and a first P+ doped plate interposed between and adjacent to the first and second N+ doped plates; and
further wherein the second P-type well comprises third and fourth N+ doped plates and a second P+ doped plate interposed between and adjacent to the third and fourth N+ doped plates.
3. The bi-directional BJT of claim 1 , wherein the first P-type well comprises a first P+ doped plate, first, second, third, and fourth N+ doped plates, and first and second gate structure, the first P+ doped plate being interposed between and adjacent to the second and third N+ doped plates, the first gate structure being interposed between and adjacent to the first and second N+ doped plate, and the second gate structure being interposed between and adjacent to the third and fourth N+ doped plate; and
further wherein the second P-type well comprises a second P+ doped plate, fifth, sixth, seventh, and eighth N+ doped plates, and third and fourth gate structure, the second P+ doped plate being interposed between and adjacent to the sixth and seventh N+ doped plates, the third gate structure being interposed between and adjacent to the fifth and sixth N+ doped plate, and the fourth gate structure being interposed between and adjacent to the seventh and eighth N+ doped plate.
4. The bi-directional BJT of claim 3 , wherein the gate structures comprise a polysilicone layer.
5. The bi-directional BJT of claim 4 , wherein the polysilicone layer is provided as a hard mask at ion implantation.
6. The bi-directional BJT of claim 1 , wherein the first, second, and third FOX portions are fabricated via a local oxidation of silicon (LOCOS) process.
7. The bi-directional BJT of claim 1 , wherein the first, second, and third FOX portions are fabricated via a shallow trench isolation (STI) process.
8. The bi-directional BJT of claim 1 , wherein the N+ buried layer comprises an n-type epitaxial layer.
9. The bi-directional BJT of claim 1 , wherein the N+ buried layer comprises a deep N-type well.
10. The bi-directional BJT of claim 1 , wherein the N+ buried layer comprises a plurality of stacked N+ buried layers.
11. The bi-directional BJT of claim 1 , wherein each P-type well comprises a stacked P-type well and P+ buried layer.
12. The bi-directional BJT of claim 1 , wherein the P-type wells are fabricated via P-type implantation.
13. The bi-directional BJT of claim 1 , wherein the N-type well region is fabricated via N-type implantation.
14. The bi-directional BJT of claim 1 , wherein the bi-directional BJT is fabricated via a single poly process.
15. The bi-directional BJT of claim 1 , wherein the bi-directional BJT is fabricated via a double poly process.
16. The bi-directional BJT of claim 1 , wherein the bi-directional BJT is fabricated via a non-epitaxial process.
17. The bi-directional BJT of claim 16 , wherein the non-epitaxial process comprises a triple-well process.