Hybrid transistor
A hybrid transistor ( 58 ) has a substrate ( 42 ) with a first (e.g., P type) well region ( 46 ) and a second (e.g., N type) well region ( 44 ) with an NP or PN junction ( 43 ) therebetween. A MOS portion ( 70 - 3 ) of the hybrid transistor ( 58 ) has an (e.g., N type) source region ( 48 ) in the first well region ( 46 ) and a gate conductor ( 52 ) overlying and insulated from the well regions ( 46, 44 ) that extends laterally at least to the junction ( 43 ). A drain or anode (D/A) portion ( 71 - 3 ) in the second well region ( 44 ) collects current 56 from the source region ( 48 ), and includes a bipolar transistor ( 78 ) having an (e.g., N+) emitter region ( 64 ), a (e.g., P type) base region ( 59 ) and a (e.g., N type) collector region ( 62 ) laterally separated from the junction ( 43 ). Different LDMOS-like or IGBT-like properties are obtained depending on whether the current 56 is extracted from the hybrid transistor ( 58 ) via the bipolar transistor ( 78 ) base ( 59 ) or emitter ( 64 ) or both. The bipolar transistor ( 78 ) is desirably a vertical hetero-junction transistor.
1. A hybrid transistor, comprising:
a substrate having therein a first well region of a first conductivity type, a second well region of a second, opposite, conductivity type, extending substantially to a first surface of the substrate, the first and second well regions forming an NP or PN junction therebetween;
a MOS portion having a source region of the second conductivity type extending to the first surface in the first well region, and having a gate conductor overlying and insulated from the first surface at least over the first well region with a first lateral end proximate the source region and a second lateral end extending at least to the NP or PN junction; and
a drain or anode (D/A) portion in the second well region, the D/A portion comprising a bipolar transistor having an emitter region of the second conductivity type, a base region of the first conductivity type communicating with the emitter region, and a collector region of the second conductivity type communicating with the base region, wherein the collector region is located in the second well region laterally separated from the NP or PN junction.
2. The hybrid transistor of claim 1 , having a principal terminal thereof coupled to the base region but not connected to the emitter region.
3. The hybrid transistor of claim 1 , having a principal terminal thereof coupled to the emitter region but not connected to the base region.
4. The hybrid transistor of claim 1 , having a principal terminal thereof coupled to both the emitter region and the base region.
5. The hybrid transistor of claim 1 , further comprising dielectric filled shallow trench isolation (STI) region laterally located in the second well region between the NP or PN junction and the collector region of the bipolar transistor.
6. The hybrid transistor of claim 5 , further comprising a sub-isolation-buried-layer (SIBL) region beneath the STI region in the second well region, and having a dopant concentration larger than the second well region.
7. The hybrid transistor of claim 1 , wherein the bipolar transistor is a hetero-junction bipolar transistor.
8. The hybrid transistor of claim 7 , wherein the base region of the bipolar transistor is formed of a different semiconductor material than the collector region.
9. The hybrid transistor of claim 1 , wherein the bipolar transistor is substantially a vertical transistor with the emitter region, the base region and the collector region arranged substantially one above the other.
10. A multifunction transistor, comprising:
a first well region of a first conductivity type;
a second well region of a second conductivity type, the second well region forming a lateral NP or PN junction with the first well region;
a MOS portion formed in at least one of the first and second well regions, the MOS portion comprising:
a source region in the first well region; and
a first well contact region in the first well region;
a common electrode shared by the source region and the first well contact region;
a drain or anode (D/A) portion formed in at least one of the first and second well regions; and
a substantially vertical hetero junction bipolar transistor in the DA portion, the substantially vertical hetero-junction bipolar transistor having a base connection and an emitter connection that may be used separately or together as a principal electrode of the multifunction transistor.
11. A multifunction transistor of claim 10 , wherein the principal electrode of the multifunction transistor is coupled to the emitter connection.
12. A multifunction transistor of claim 10 , wherein the principal electrode of the multifunction transistor is coupled to the base connection.
13. A multifunction transistor of claim 10 , wherein the principal electrode of the multifunction transistor is coupled to both the base connection and the emitter connection.
14. The multifunction transistor of claim 10 , further comprising in the MOS portion a gate conductor insulated at least from the first well region and extending laterally substantially from the source region to at least the NP or PN junction.