Power devices, structures, components, and methods using lateral drift, fixed net charge, and shield
Lateral power devices where immobile electrostatic charge is emplaced in dielectric material adjoining the drift region. A shield gate is interposed between the gate electrode and the drain, to reduce the Miller charge. In some embodiments the gate electrode is a trench gate, and in such cases the shield electrode too is preferably vertically extended.
1. A semiconductor device comprising:
a first-conductivity-type source region;
a second-conductivity-type body region interposed between said source region and a semiconductor drift region;
a gate electrode which is capacitively coupled to controllably invert a portion of said body region, to controllably form therein a channel which connects said source region to said drift region;
wherein said drift region is laterally interposed between said body region and a first-conductivity-type drain region;
permanent charge, which is embedded in at least one insulating region which adjoins said drift region, and which has a polarity which tends to deplete a layer of said drift region in proximity to said insulating region;
a shield electrode, which is at least partly interposed between said gate electrode and said drain to reduce capacitive coupling between said gate and said drain; and
a dielectric-filled trench within said drift region, which lies at least partly beneath said gate electrode;
wherein said drift region is formed as a well.
2. The semiconductor device of claim 1 , further comprising a buried region within said drift region.
3. The semiconductor device of claim 1 , wherein said channel and said drift region both carry current flow in a predominantly horizontal plane.
4. The semiconductor device of claim 1 , wherein said channel lies in a plane which is predominantly normal to the plane of current flow in said drift region.
5. The semiconductor device of claim 1 , wherein said channel lies in a plane which is predominantly normal to the surface of a semiconductor die, and said drift region carries current flow which is predominantly parallel to said surface.
6. The semiconductor device of claim 1 , wherein said gate electrode and said shield electrode are both predominantly planar.
7. The semiconductor device of claim 1 , wherein said gate electrode and said shield electrode both have a minimum width which is less than a respective maximum vertical thickness thereof.
8. The semiconductor device of claim 1 , wherein said gate electrode and said shield electrode both lie in the same plane of metallization.
9. The semiconductor device of claim 1 , wherein said shield electrode is connected to a fixed potential, but said gate electrode is not.
10. The semiconductor device of claim 1 , wherein said drift region is part of a semiconductor-on-insulator structure.
11. A semiconductor device comprising:
a first-conductivity-type source region;
a second-conductivity-type body region interposed between said source region and a semiconductor drift region of said second conductivity type;
a gate electrode which is capacitively coupled to controllably invert a portion of said body region, to controllably form therein a channel which connects said source region to said drift region; wherein said semiconductor drift region is laterally interposed between said body region and a first-conductivity-type drain region; and
an insulated trench
which laterally adjoins said drift region, and
which contains immobile net electrostatic charge which is capacitively coupled to said drift region, and
which is laterally tapered.
12. The semiconductor device of claim 11 , wherein said charge is positive, and said first conductivity type is n-type.
13. The semiconductor device of claim 11 , further comprising a shield electrode which is not electrically connected to said gate electrode, and which at least partially overlies said drift region.
14. The semiconductor device of claim 11 , wherein said insulated trench is wider near said drain region than near said source region.
15. The semiconductor device of claim 11 , wherein said insulated trench is wider near said source region than near said drain region.
16. The semiconductor device of claim 11 , wherein said first conductivity type is n-type.