IGBT with bidirectional conduction
View Patent ↗An IGBT device includes a drift region, a collector contact, an injector region, a pair of junction implants, a gate contact, and an emitter contact. The injector region includes a first surface in contact with the collector contact, a second surface opposite the first surface and in contact with the drift region, and at least one bypass region running between the first surface and the second surface. Notably, the at least one bypass region has a charge carrier that is different from that of the injector region. The pair of junction implants is in the drift region along a surface of the drift region opposite the injector region. The gate contact and the emitter contact are on the surface of the drift region opposite the injector region.
1. A method comprising:
depositing an injector region on a substrate;
separately depositing at least one bypass region through the injector region, wherein a charge carrier of the bypass region is different than that of the injector region;
providing a drift region on the injector region opposite the substrate, the drift region comprising silicon carbide;
providing a pair of junction barrier implants in the drift region opposite the injector region;
providing a gate contact and an emitter contact on the drift region opposite the injector region.
2. The method of claim 1 wherein depositing the injector region and the at least one bypass region comprises:
providing a blanket injector region having a first charge carrier;
etching at least one trench through the blanket injector region; and
providing the at least one bypass region in the at least one trench, wherein the charge carrier of the at least one bypass region is different from that of the blanket injector region.
3. The method of claim 1 wherein the ratio of the cross-sectional area of the at least one bypass region to the cross-sectional area of the injector region is less than about 1:5.
4. The method of claim 1 wherein each one of the pair of junction barrier implants are laterally separated from one another along the drift region opposite the substrate.
5. The method of claim 1 wherein:
the injector region is a highly doped P region;
the at least one bypass region is a highly doped N region; and
the drift region is a lightly doped N region.
6. The method of claim 5 wherein:
the injector region has a doping concentration in the range of about 1E16 cm −3 to about 1E21 cm −3 ;
the at least one bypass region has a doping concentration in the range of about 1E18 cm —3 to about 1E21 cm −3 ; and
the drift region has a doping concentration in the range of about 1E13 cm −3 to about 1E15 cm −3 .
7. The method of claim 1 further comprising providing a charge storage region in the middle of the drift region between each lateral edge of the drift region, such that the charge storage region separates the drift region into an upper drift region and a lower drift region.
8. The method of claim 7 wherein:
the injector region is a highly doped P-type region;
the at least one bypass region is a highly doped N-type region;
the drift region is a lightly doped N-type region; and
the charge storage region is a highly doped N-type region.
9. The method of claim 8 wherein:
the injector region has a doping concentration in the range of about 1E16 cm −3 to about 1E21 cm −3 ;
the at least one bypass region has a doping concentration in the range of about 1E18 cm —3 to about 1E21 cm −3 ;
the drift region has a doping concentration in the range of about 1E13 cm −3 to about 1E15 cm −3 ; and
the charge storage region has a doping concentration from about 1E13 cm −3 to about 1E15 cm −3 .
10. The method of claim 1 further comprising removing the substrate and providing a collector contact on the injector region opposite the drift region.