Diode structure to suppress parasitic current
A diode conducts current between an anode terminal and a cathode terminal. The diode includes a parasitic transistor formed between one of the terminals and the substrate. The diode also includes a second transistor that competes with the parasitic transistor to direct current flow between the anode terminal and the cathode terminal.
1. A diode comprising:
a substrate of a first conductivity type;
an epitaxial region of a second conductivity type adjacent the substrate;
a first terminal;
a second terminal spaced from the first terminal;
a first region of the first conductivity type connected to the first terminal and the epitaxial region;
a second region of the first conductivity type connected to the second terminal and the epitaxial region; and
a third region of the second conductivity type connected to the second terminal and the epitaxial region.
2. The diode of claim 1 , further comprising a third terminal electrically connected to the substrate.
3. The diode of claim 1 , wherein the second region is located between the third region and the first region.
4. The diode of claim 1 , wherein the third region is located between the second region and the first region.
5. The diode of claim 1 , further comprising an electrically insulating region between the first region and the second region.
6. The diode of claim 1 , wherein each of the first region, the second region, the third region, and the second terminal form a ring around the first terminal.
7. The diode of claim 1 , wherein the second region comprises a plurality of regions of the first conductivity type.
8. The diode of claim 1 , wherein the third region comprises a plurality of regions of the second conductivity type.
9. A diode for conducting current between a first terminal and a second terminal, the diode comprising:
a substrate;
an epitaxial region of a first conductivity type adjacent the substrate;
a first doped region of a second conductivity type connected to the first terminal and the epitaxial region; and
means for passing, current from the epitaxial region to the second terminal to divert current from an undesired location.
10. The diode of claim 9 , wherein the means for passing current from the epitaxial region to the second terminal comprises a second doped region of the first conductivity type connected to the second terminal and the epitaxial region.
11. The diode of claim 9 , the means for passing current from the epitaxial region to the second terminal comprises a third doped region of the second conductivity type connected to the second terminal and the epitaxial region.
12. The diode of claim 9 , wherein the means for passing current from the epitaxial region to the second terminal comprises:
a second doped region of the first conductivity type connected to the second terminal and the epitaxial region; and
a third doped region of the second conductivity type connected to the second terminal and the epitaxial region.
13. The diode of claim 12 , wherein the second terminal comprises a metal layer connected to the second doped region and the third doped region.
14. A diode comprising:
a substrate of a first conductivity type;
an epitaxial region of a second conductivity type adjacent the substrate;
a first terminal adjacent the epitaxial region;
a second terminal adjacent the epitaxial region and spaced from the first terminal;
a first transistor comprising:
a first region of the first conductivity type;
the epitaxial region connected to the first region; and
the substrate connected to the epitaxial region;
a second transistor comprising:
the first region;
the epitaxial region connected to the first region; and
a second region of the first conductivity type, connected to the epitaxial region and the second terminal and spaced from the first region; and
a third region of the second conductivity type, connected to the epitaxial region and the second terminal.
15. The diode of claim 14 , wherein the first transistor and the second transistor are pnp transistors.
16. The diode of claim 14 , wherein a doping concentration of the third region is greater than a doping concentration of the epitaxial region.
17. The diode of claim 14 , further comprising a third terminal electrically connected to the substrate.
18. The diode of claim 14 , further comprising a buried layer between the substrate and the epitaxial region.
19. The diode of claim 14 , further comprising an electrically insulating region between the first region and the third region.