ESD protection with integrated LDMOS triggering junction
View Patent ↗An electrostatic discharge (ESD) protection device includes a semiconductor substrate, a base region in the semiconductor substrate and having a first conductivity type, an emitter region in the base region and having a second conductivity type, a collector region in the semiconductor substrate, spaced from the base region, and having the second conductivity type, a breakdown trigger region having the second conductivity type, disposed laterally between the base region and the collector region to define a junction across which breakdown occurs to trigger the ESD protection device to shunt ESD discharge current, and a gate structure supported by the semiconductor substrate over the breakdown trigger region and electrically tied to the base region and the emitter region. The lateral width of the breakdown trigger region is configured to establish a voltage level at which the breakdown occurs.
1. An electronic apparatus comprising an electrostatic discharge (ESD) protection device, the ESD protection device comprising:
a semiconductor substrate;
a base region in the semiconductor substrate and having a first conductivity type;
an emitter region in the base region and having a second conductivity type;
a collector region in the semiconductor substrate, spaced from the base region, and having the second conductivity type;
a breakdown trigger region doped to effectively have the second conductivity type, and disposed laterally between the base region and the collector region to define a junction across which breakdown occurs to trigger the ESD protection device to shunt ESD discharge current; and
a gate structure supported by the semiconductor substrate over the breakdown trigger region and electrically tied via an interconnect to the base region and the emitter region;
wherein the lateral width of the breakdown trigger region is configured to establish a voltage level at which the breakdown occurs.
2. The electronic apparatus of claim 1 , the ESD protection device further comprising a buried doped isolating layer in the semiconductor substrate, having the second conductivity type, and extending laterally across the base, emitter, and collector regions, wherein:
the breakdown trigger region comprises a well;
the collector region comprises a doped isolating well, having the second conductivity type, and electrically coupled to the buried doped isolating layer; and
a lower boundary of the well of the breakdown trigger region is shallower than a depth at which the doped isolating well reaches the buried doped isolating layer.
3. The electronic apparatus of claim 2 , wherein the doped isolating well and the buried doped isolating layer have higher dopant concentration levels than the breakdown trigger region.
4. The electronic apparatus of claim 2 , the ESD protection device further comprising a well region in the semiconductor substrate, electrically separated from the base and emitter regions by the doped isolating well, and having the first conductivity type, wherein an ESD event forms a silicon controlled rectifier (SCR) device comprising the base, emitter, collector, and well regions, the SCR device being configured to shunt the ESD discharge current between the well region and the emitter region.
5. The electronic apparatus of claim 4 , wherein:
the well region is configured as a further base region in which a further emitter region is disposed; and
the collector region is a common collector for the further base region and the further emitter region such that the ESD protection device is configured as a dual polarity ESD protection device.
6. The electronic apparatus of claim 5 , wherein the buried doped isolating layer does not extend laterally under the further base region.
7. The electronic apparatus of claim 1 , wherein the gate structure extends across an entire extent of the lateral width of the breakdown trigger region.
8. The electronic apparatus of claim 1 , further comprising a shallow trench isolation (STI) region in the semiconductor substrate, wherein the STI region and the breakdown trigger region laterally overlap to an extent such that the STI region does not overlap a portion of the breakdown trigger region.
9. The electronic apparatus of claim 1 , wherein the breakdown trigger region comprises a well, and the junction is established between the base region and the well of the breakdown trigger region.
10. The electronic apparatus of claim 1 , wherein:
the breakdown trigger region comprises a well;
the semiconductor substrate comprises an epitaxial layer having the first conductivity type that defines a surface of the semiconductor substrate;
the base, emitter, collector, and breakdown trigger regions are disposed in the epitaxial layer; and
the base region and the well of the breakdown trigger region laterally abut one another to define the junction such that the junction is not defined by the epitaxial layer.
11. The electronic apparatus of claim 10 , wherein:
a dopant concentration level of the breakdown trigger region is higher than a dopant concentration level of the epitaxial layer; and
the breakdown trigger region is configured to be fully depleted when the breakdown occurs.
12. An electronic apparatus comprising:
a semiconductor substrate;
a pair of terminals supported by the semiconductor substrate; and
a dual polarity electrostatic discharge (ESD) protection device comprising a pair of bipolar transistor devices sharing a common collector region, each bipolar transistor comprising:
base and emitter regions in the semiconductor substrate and electrically connected to a respective one of the pair of terminals, the base region having a first conductivity type, the emitter region having a second conductivity type;
a breakdown trigger region in the semiconductor substrate laterally between the base region and the common collector region to define a junction across which breakdown occurs to trigger the dual polarity ESD protection device, the breakdown trigger region doped to effectively have the second conductivity type; and
a gate structure supported by the semiconductor substrate over the junction and electrically connected via an interconnect to a respective one of the terminals and to the base and emitter regions;
wherein the lateral width of the breakdown trigger region is configured to establish a voltage level at which the breakdown occurs.
13. The electronic apparatus of claim 12 , wherein:
the breakdown trigger region comprises a well;
the dual polarity ESD protection device further comprises a buried doped isolating layer in the semiconductor substrate, the buried doped isolating layer extending laterally across the pair of bipolar transistor devices;
the common collector region comprises a doped isolating well, and electrically coupled to the buried doped isolating layer; and
a lower boundary of the well of the breakdown trigger region is shallower than a depth at which the doped isolating well reaches the buried doped isolating layer.
14. The electronic apparatus of claim 1 , wherein:
the breakdown trigger region comprises a well;
the ESD protection device further comprises a buried doped isolating layer in the semiconductor substrate, having the second conductivity type, and extending laterally across the base, emitter, and collector regions; and
the well of the breakdown trigger region is spaced from the buried doped isolating layer.
15. The electronic apparatus of claim 1 , wherein:
the breakdown trigger region comprises a well;
the collector region comprises an inner well region and an outer well region that flanks the inner well region; and
the well of the breakdown trigger region abuts the outer well region.
16. The electronic apparatus of claim 12 , wherein:
the breakdown trigger region comprises a well;
the dual polarity ESD protection device further comprises a buried doped isolating layer in the semiconductor substrate, the buried doped isolating layer extending laterally across the pair of bipolar transistor devices; and
the well of the breakdown trigger region is spaced from the buried doped isolating layer.
17. The electronic apparatus of claim 12 , wherein:
the breakdown trigger region comprises a well;
the collector region comprises an inner well region and an outer well region that flanks the inner well region;
the inner well region has a higher dopant concentration level than the outer well region; and
the well of the breakdown trigger region abuts the outer well region.
18. The electronic apparatus of claim 12 , wherein:
the breakdown trigger region comprises a well;
the semiconductor substrate comprises an epitaxial layer having the first conductivity type that defines a surface of the semiconductor substrate;
the base, emitter, collector, and breakdown trigger regions are disposed in the epitaxial layer;
a dopant concentration level of the breakdown trigger region is higher than a dopant concentration level of the epitaxial layer;
the base region and the well of the breakdown trigger region laterally abut one another to define the junction such that the junction is not defined by the epitaxial layer; and
the gate structure extends across an entire extent of the lateral width of the breakdown trigger region.
19. The electronic apparatus of claim 1 , wherein the breakdown trigger region comprises a well disposed laterally between the base region and the collector region to define the junction across which breakdown occurs.
20. The electronic apparatus of claim 12 , wherein the breakdown trigger region comprises a well disposed laterally between the base region and the collector region to define the junction across which breakdown occurs.
21. The electronic apparatus of claim 12 , further comprising a shallow trench isolation (STI) region in the semiconductor substrate, wherein the STI region and the breakdown trigger region laterally overlap to an extent such that the STI region does not overlap a portion of the breakdown trigger region.