Silicon controlled rectifiers with field plate
The present disclosure relates to semiconductor structures and, more particularly, to silicon controlled rectifiers with field plate structures and methods of manufacture. The structure includes: a plurality of wells of a first type in a semiconductor substrate; a well of a second type in the semiconductor substrate, the well of the second type surrounding the plurality of wells of the first type; an isolation structure surrounding the plurality of wells of the first type, the isolation structure isolating the well of the second type from the plurality of wells of the first type; and a plurality of field plates on the isolation structure, the plurality of field plates surround the plurality of wells of the first type.
1 . A structure comprising:
a plurality of wells of a first type in a semiconductor substrate;
a well of a second type in the semiconductor substrate, the well of the second type surrounding each of the plurality of wells of the first type such that the well of the second type is provided between adjacent wells of the plurality of wells of the first type;
an isolation structure surrounding the plurality of wells of the first type, the isolation structure completely covering the well of the second type provided between the adjacent wells of the plurality of wells of the first type and extending onto the adjacent wells of the plurality of wells of the first type, the isolation structure further isolating the well of the second type from the plurality of wells of the first type;
a plurality of field plates on the isolation structure, the plurality of field plates surround the plurality of wells of the first type; and
an additional well of the first type within the plurality of wells, the additional well having a lower doping concentration than the plurality of wells.
2 . The structure of claim 1 , wherein the plurality of wells of the first type comprise P-wells connected to respective terminals and the well of the second type comprises an N-well.
3 . The structure of claim 2 , wherein the N-well is a ring structure surrounding the P-wells.
4 . The structure of claim 2 , wherein the isolation structure comprises LOCOS and the plurality of field plates comprise polysilicon material on the LOCOS.
5 . The structure of claim 4 , wherein the polysilicon material comprises a ring structure surrounding each of the P-wells.
6 . The structure of claim 2 , wherein the isolation structure comprises shallow trench isolation structures and the plurality of field plates comprise polysilicon material on the shallow trench isolation structures.
7 . The structure of claim 2 , wherein the P-wells are adjacent P-wells connected to a respective terminal and each of the P-wells are isolated from one another by the isolation structure.
8 . The structure of claim 1 , wherein the field plates are electrically coupled to the well of the second type.
9 . The structure of claim 8 , wherein the well of the second type acts as a pick-up to a floating n-type region.
10 . The structure of claim 1 , wherein the isolation structure comprises two isolation structures extending between the plurality of wells of the first type and the well of the second type.
11 . The structure of claim 10 , further comprising a diffusion region between the two isolation structures and within the well of the second type.
12 . The structure of claim 1 , wherein the additional well comprises a same dopant type than the plurality of wells.
13 . A structure comprising:
a plurality of P-wells in a semiconductor substrate;
an N-well isolating the plurality of P-wells by surrounding each of the plurality of P-wells;
an isolation structure surrounding the plurality of P-wells and isolating the plurality of P-wells from the N-well;
field plates on the isolation structure, the field plates forming a ring about the plurality of P-wells; and
an additional P-well within the plurality of P-wells, the additional P-well having a lower doping concentration than the plurality of P-wells.
14 . The structure of claim 13 , wherein the field plates comprise polysilicon material and the isolation structure comprises LOCOS.
15 . The structure of claim 13 , wherein the field plates comprise polysilicon material and the isolation structure comprises shallow trench isolation structures.
16 . The structure of claim 13 , wherein the isolation structure comprises two isolation structures separated by a diffusion region in the N-well.
17 . The structure of claim 13 , wherein the plurality of P-wells connect to separate terminals and the separate terminals are surrounded by both the isolation structure and the field plates.
18 . The structure of claim 13 , wherein the P-wells comprise high-voltage P-wells and further comprising additional wells of a same dopant type and different dopant concentration within the P-wells.
19 . The structure of claim 13 , wherein the N-wells are electrically coupled to the field plates and are devoid of terminals.
20 . A method comprising:
forming a plurality of wells of a first type in a semiconductor substrate;
forming a well of a second type in the semiconductor substrate, the well of the second type surrounding each of the plurality of wells of the first type such that the well of the second type is provided between adjacent wells of the plurality of wells of the first type;
forming an isolation structure surrounding the plurality of wells of the first type, the isolation structure completely covering the well of the second type provided between the adjacent wells of the plurality of wells of the first type and extending onto the adjacent wells of the plurality of wells of the first type, the isolation structure further isolating the well of the second type from the plurality of wells of the first type;
forming a plurality of field plates on the isolation structure, the plurality of field plates surround the plurality of wells of the first type; and
forming an additional well of the first type within the plurality of wells, the additional well having a lower doping concentration than the plurality of wells, and a top surface of the additional well being above a top surface of the plurality of wells.