FinFET thyristors with embedded transistor control for protecting high-speed communication systems
Fin field-effect transistor (FinFET) thyristors for protecting high-speed communication interfaces are provided. In certain embodiments herein, high voltage tolerant FinFET thyristors are provided for handling high stress current and high RF power handling capability while providing low capacitance to allow wide bandwidth operation. Thus, the FinFET thyristors can be used to provide electrical overstress protection for ICs fabricated using FinFET technologies, while addressing tight radio frequency design window and robustness. In certain implementations, the FinFET thyristors include a first thyristor, a FinFET triggering circuitry and a second thyristor that serves to provide bidirectional blocking voltage and overstress protection. The FinFET triggering circuitry also enhances turn-on speed of the thyristor and/or reduces total on-state resistance.
1. A fin field-effect transistor (FinFET) thyristor protection structure for protecting a high-speed communication interface, the FinFET thyristor protection structure comprising:
a signal terminal and a ground terminal;
a thyristor comprising a PNP bipolar transistor and an NPN bipolar transistor, wherein the PNP bipolar transistor includes an emitter connected to the signal terminal and formed from a first plurality of p-type active (P+) regions extending in a first direction in an n-type well (NW), a base formed from the NW, and a collector formed from a p-type well (PW), and wherein the NPN bipolar transistor includes an emitter connected to the ground terminal and formed from a first plurality of n-type active (N+) regions extending in the first direction in the PW, a base formed from the PW, and a collector formed from the NW; and
a first cascoded p-type FinFET and a second cascoded p-type FinFET connected in series and configured to trigger activation of the thyristor in response to an electrical overstress event received between the signal terminal and the ground terminal, wherein a source and a gate of the first cascoded p-type FinFET are connected to the signal terminal, and wherein a drain of the second cascoded p-type FinFET is formed in the NW and connected to the base of the NPN bipolar transistor by a direct metal connection in a second direction substantially perpendicular to the first direction, and wherein the first cascoded p-type FinFET and the second cascoded p-type FinFET are configured to activate to provide a trigger current from the signal terminal in response to the electrical overstress event received between the signal terminal and the ground terminal, the trigger current flowing in the second direction via the direct metal connection to the base of the NPN bipolar transistor.
2. The FinFET thyristor protection structure of claim 1 , wherein a source and a gate of the second cascoded p-type FinFET are connected to a drain of the first cascoded p-type FinFET.
3. The FinFET thyristor protection structure of claim 1 , further comprising:
a first stacked PNP bipolar transistor, the first cascoded p-type FinFET including a body connected to a base of the first stacked PNP bipolar transistor and a drain connected to a collector of the first stacked PNP bipolar transistor, wherein the source and the gate of the first cascoded p-type FinFET are connected to an emitter of the first stacked PNP bipolar transistor; and
a second stacked PNP bipolar transistor, the second cascoded p-type FinFET including a body connected to a base of the second stacked PNP bipolar transistor, and a source and a gate connected to an emitter of the second stacked PNP bipolar transistor, wherein the drain of the second cascoded p-type FinFET is connected to a collector of the second stacked PNP bipolar transistor.
4. The FinFET thyristor protection structure of claim 3 , wherein the base of the PNP bipolar transistor is connected to the bases of the first stacked PNP bipolar transistor and the second stacked PNP bipolar transistor.
5. The FinFET thyristor protection structure of claim 3 , wherein the direct metal connection further connects the base of the NPN bipolar transistor to the collector of the second stacked PNP bipolar transistor and the collector of the PNP bipolar transistor.
6. The FinFET thyristor protection structure of claim 1 , wherein the PNP bipolar transistor and the NPN bipolar transistor are cross-coupled.
7. The FinFET thyristor protection structure of claim 1 , wherein the source of the first cascoded p-type FinFET is formed from a first plurality of P+ regions in the NW, a drain of the first cascoded p-type FinFET is formed from a second plurality of P+ regions in the NW, and the gate of the first cascoded p-type FinFET is formed from a first plurality of gate fins over the NW.
8. The FinFET thyristor protection structure of claim 7 , wherein a source of the second cascoded p-type FinFET is formed from the second plurality of P+ regions in the NW, the drain of the second cascoded p-type FinFET is formed from a third plurality of P+ regions, and a gate of the second cascoded p-type FinFET is formed from a second plurality of gate fins over the NW.
9. The FinFET thyristor protection structure of claim 1 , further comprising a resistor connecting a substrate terminal to the drain of the second cascoded p-type FinFET.
10. The FinFET thyristor protection structure of claim 1 , wherein a base-to-emitter junction of the PNP bipolar transistor is an open state.
11. The FinFET thyristor protection structure of claim 1 , wherein a current path through the first cascoded p-type FinFET and the second cascoded p-type FinFET is substantially perpendicular to a current path through the thyristor.
12. The FinFET thyristor protection structure of claim 1 , further comprising:
a substrate terminal; and
a resistor connecting the substrate terminal to the drain of the second cascoded p-type FinFET,
wherein the substrate terminal is decoupled from the ground terminal.
13. A fin field-effect transistor (FinFET) thyristor protection circuit comprising:
a thyristor comprising a PNP bipolar transistor and an NPN bipolar transistor, wherein the PNP bipolar transistor includes an emitter connected to a signal terminal and formed from a first plurality of p-type active (P+) regions extending in a first direction in an n-type well (NW), a base formed from the NW, and a collector formed from a p-type well (PW), and wherein the NPN bipolar transistor includes an emitter connected to a ground terminal and formed from a first plurality of n-type active (N+) regions extending in the first direction in the PW, a base formed from the PW, and a collector formed from the NW; and
FinFET triggering circuitry comprising a first cascoded p-type FinFET and a second cascoded p-type FinFET connected in series and configured to trigger activation of the thyristor in response to an electrical overstress event received between the signal terminal and the ground terminal, wherein a source and a gate of the first cascoded p-type FinFET are connected to the signal terminal, and wherein a drain of the second cascoded p-type FinFET is formed in the NW and connected to the base of the NPN bipolar transistor by a direct metal connection in a second direction substantially perpendicular to the first direction, and wherein the first cascoded p-type FinFET and the second cascoded p-type FinFET are configured to activate to provide a trigger current from the signal terminal in response to the electrical overstress event received between the signal terminal and the ground terminal, the trigger current flowing in the second direction via the direct metal connection to the base of the NPN bipolar transistor.
14. The FinFET thyristor protection circuit of claim 13 , wherein a source and a gate of the second cascoded p-type FinFET are connected to a drain of the first cascoded p-type FinFET.
15. The FinFET thyristor protection circuit of claim 13 , further comprising:
a first stacked PNP bipolar transistor, the first cascoded p-type FinFET including a body connected to a base of the first stacked PNP bipolar transistor and a drain connected to a collector of the first stacked PNP bipolar transistor, wherein the source and the gate of the first cascoded p-type FinFET are connected to an emitter of the first stacked PNP bipolar transistor; and
a second stacked PNP bipolar transistor, the second cascoded p-type FinFET including a body connected to a base of the second stacked PNP bipolar transistor, and a source and a gate connected to an emitter of the second stacked PNP bipolar transistor, wherein the drain of the second cascoded p-type FinFET is connected to a collector of the second stacked PNP bipolar transistor.
16. The FinFET thyristor protection circuit of claim 15 , wherein the base of the PNP bipolar transistor is connected to the bases of the first stacked PNP bipolar transistor and the second stacked PNP bipolar transistor.
17. The FinFET thyristor protection circuit of claim 15 , wherein the direct metal connection further connects the base of the NPN bipolar transistor to the collector of the second stacked PNP bipolar transistor and the collector of the PNP bipolar transistor.
18. The FinFET thyristor protection circuit of claim 13 , wherein the PNP bipolar transistor and the NPN bipolar transistor are cross-coupled.
19. The FinFET thyristor protection circuit of claim 13 , wherein the source of the first cascoded p-type FinFET is formed from a first plurality of P+ regions in the NW, a drain of the first cascoded p-type FinFET is formed from a second plurality of P+ regions in the NW, and the gate of the first cascoded p-type FinFET is formed from a first plurality of gate fins over the NW.
20. A method of protecting an interface of a communication system, the method comprising:
receiving an electrical overstress event between a signal terminal and a ground terminal;
providing a first current path from the signal terminal to the ground terminal through FinFET triggering circuitry in response to the electrical overstress event, the FinFET triggering circuitry comprising a first cascoded p-type FinFET and a second cascoded p-type FinFET connected in series, wherein a source and a gate of first cascoded p-type FinFET are connected to the signal terminal, and wherein a drain of the second cascoded p-type FinFET is formed in an n-type well (NW); and
triggering activation of a thyristor using the FinFET triggering circuitry, wherein the thyristor comprises a PNP bipolar transistor and an NPN bipolar transistor, wherein the PNP bipolar transistor includes an emitter connected to the signal terminal and formed from a first plurality of p-type active (P+) regions extending in a first direction in the NW, a base formed from the NW, and a collector formed from a p-type well (PW), and wherein the NPN bipolar transistor includes an emitter connected to the ground terminal and formed from a first plurality of n-type active (N+) regions extending in the first direction in the PW, a base formed from the PW and connected to the drain of the second cascoded p-type FinFET by a direct metal connection in a second direction substantially perpendicular to the first direction, and a collector formed from the NW, and wherein triggering activation of the FinFET triggering circuitry includes the first cascoded p-type FinFET and the second cascoded p-type FinFET providing a trigger current from the signal terminal in response to the electrical overstress event received between the signal terminal and the ground terminal, the trigger current flowing in the second direction via the direct metal connection to the base of the NPN bipolar transistor.
21. The FinFET thyristor protection structure of claim 1 , wherein a second plurality of P+ regions are formed in the NW, the second plurality of P+ regions forming both a drain of the first cascoded p-type FinFET and a source of the second cascoded p-type FinFET.
22. The FinFET thyristor protection structure of claim 7 , wherein the first plurality of P+ regions in the NW forming the source of the first cascoded p-type FinFET and the second plurality of P+ regions in the NW forming the drain of the first cascoded p-type FinFET extend in the first direction.