Silicon carbide power bipolar devices with deep acceptor doping
View Patent ↗In a general aspect, a power semiconductor device can include a collector region disposed on a substrate, the collector region can include n-type silicon carbide (SiC). The power semiconductor device can also include a base region disposed on the collector region. The base region can include p-type SiC doped with gallium. The power semiconductor device can include an emitter region disposed on the base region. The emitter region can include n-type SiC carbide.
1. A power semiconductor device, comprising:
a collector region disposed on a substrate, the collector region including n-type silicon carbide (SiC);
a base region disposed on the collector region, the base region including p-type SiC doped with gallium (Ga), the p-type SiC of the base region being further doped with aluminum; and
an emitter region disposed on the base region, the emitter region including n-type SiC carbide.
2. The power semiconductor device of claim 1 , wherein the power semiconductor device is one of a bipolar junction transistor (BJT), an insulated-gate bipolar transistor (IGBT) and a thyristor.
3. The power semiconductor device of claim 1 , further comprising an Ohmic contact including:
a sub-contact region disposed in the base region and laterally spaced from the emitter region, the sub-contact region being doped with aluminum; and
a base terminal contact disposed on the sub-contact region.
4. The power semiconductor device of claim 1 , wherein:
the collector region, the base region and the emitter region are arranged as a vertical stack, the emitter region being an elevated structure on the stack that is defined by a first sidewall and a second sidewall of the emitter region; and
an interface between the emitter region and the base region defines an intrinsic base region of the power semiconductor device.
5. The power semiconductor device of claim 4 , wherein the intrinsic base region includes a first portion having a width that is narrower than a width of the emitter region and at least one second portion that is adjacent to the first portion, the first portion being thinner than the second portion.
6. The power semiconductor device of claim 5 , wherein the first portion of the intrinsic base region is substantially centered between the first sidewall and the second sidewall of the emitter region.
7. The power semiconductor device of claim 4 , further comprising a dielectric layer disposed on at least a portion of an upper surface of the emitter region, the first sidewall of the emitter region and a portion of the base region that is adjacent the first sidewall of the emitter region.
8. The power semiconductor device of claim 7 , wherein the portion of the base region adjacent the first sidewall of the emitter region is a first portion, the dielectric layer being further disposed on the second sidewall of the emitter region and a second portion of the base region adjacent the second sidewall of the emitter region.
9. The power semiconductor device of claim 1 , wherein the p-type SiC of the base region is a first base region layer, the power semiconductor device further comprising:
a second base region layer disposed on the first base region layer, the second base region layer including p-type SiC doped with aluminum.
10. The power semiconductor device of claim 9 , wherein a dopant dose of aluminum in the second base region layer is higher than a dopant dose of gallium in the first base region layer.
11. The power semiconductor device of claim 1 , wherein the p-type SiC of the base region is a first base region layer, the power semiconductor device further comprising:
a second base region layer disposed on the first base region layer, the second base region layer including p-type SiC doped with aluminum; and
a third base region layer disposed on the second base region layer, the third base region layer including p-type SiC doped with gallium.
12. The power semiconductor device of claim 1 , wherein the collector region defines an n-type cathode of a thyristor, the base region defines a p-type base region of the thyristor and the emitter region defines an n-type base region of the thyristor,
the power semiconductor device further comprising a p-type anode disposed on the n-type base region.
13. The power semiconductor device of claim 12 , further comprising a p-type depletion stopper region disposed between the n-type cathode and the p-type base region, the thyristor being a punch-through thyristor.
14. The power semiconductor device of claim 1 , wherein the power semiconductor device is an insulated-gate bipolar transistor (IGBT), the base region including a p-type field-stop region of the IGBT, the power semiconductor device further comprising:
a p-type drift region disposed between the p-type field stop region and the emitter region; and
a field effect transistor (FET) including:
a source region operationally coupled with the emitter region;
a drain region operationally coupled with the base region; and
a gate terminal configured to control current flow between the source region and the drain region.
15. The power semiconductor device of claim 1 , wherein:
the base region includes an intrinsic base region and an extrinsic base region,
the intrinsic base region has a Ga doping concentration that is more than fifty percent of a total acceptor doping concentration of the intrinsic base region, and
at least a portion of the extrinsic base region has an aluminum (Al) doping concentration that is more than fifty percent of a total acceptor doping concentration of the extrinsic base region.
16. The power semiconductor device of claim 1 , wherein:
the base region includes an intrinsic base region and an extrinsic base region; and
the emitter region is disposed on the intrinsic base region,
the power semiconductor device further comprising a base contact including:
a sub-contact region disposed in the extrinsic base region; and
a base terminal contact disposed on the sub-contact region,
the intrinsic base region being predominantly doped with gallium, and
the extrinsic base region being predominantly doped with aluminum at least in the sub-contact region.
17. A power bipolar junction transistor (BJT), comprising:
a substrate including n-type silicon carbide (SiC);
a buffer layer including n-type SiC;
a collector region disposed on the buffer layer, the collector region including n-type SiC;
a base region including:
a first base layer disposed on the collector region, the first base layer including gallium doped p-type SiC, the gallium doped p-type SiC of the first base layer being further doped with aluminum; and
a second base layer disposed on the first base layer, the second base layer including aluminum doped p-type SiC, the second base layer having a resistivity that is lower than a resistivity of the first base layer,
the base region having a recess defined therein, the recess extending through the second base layer to the first base layer; and
an emitter region including n-type SiC, the emitter region having
a first portion disposed in the recess and directly on the first base layer; and
a second portion disposed directly on the second base layer.
18. The power BJT of claim 17 , further comprising:
a base terminal contact disposed on the second base layer, an interface between the base terminal contact and the second base layer defining an Ohmic contact; and
an emitter terminal contact disposed on the emitter region.
19. The power BJT of claim 17 , further comprising a dielectric layer disposed on at least a portion of an upper surface of the emitter region, a sidewall of the emitter region and a portion of the second base layer that is adjacent the sidewall of the emitter region.
20. A power bipolar junction transistor (BJT), comprising:
a substrate including n-type silicon carbide (SiC);
a collector region disposed on the substrate, the collector region including n-type SiC;
a base region disposed on the collector region, the base region including gallium doped p-type SiC, the gallium doped SiC of the base region being further doped with aluminum;
an emitter region disposed on the base region, the emitter region having a width that is narrower than a width of the base region;
a sub-contact region disposed in the base region and laterally disposed from the emitter region; and
a base terminal contact disposed on the sub-contact region.
21. The power BJT of claim 20 , wherein the gallium doped SiC of the base region is a first base layer, the base region further including a second base layer disposed on the first base layer, the second base layer including aluminum doped p-type SiC.
22. The power BJT of claim 21 , wherein the base region further includes a third base layer disposed on the second base layer, the third base layer including gallium doped p-type SiC.
23. The power BJT of claim 20 , wherein the gallium doped SiC of the base region is a first base layer, the base region further including a second base layer disposed between the collector region and the first base layer, the second base layer including aluminum doped p-type SiC.
24. The power BJT of claim 20 , further comprising a dielectric layer disposed on at least a portion of an upper surface of the emitter region, a sidewall of the emitter region and a portion of the base region adjacent the sidewall of the emitter region.