Electronic device including a drift region
An electronic device can include a semiconductor layer having a primary surface, a drift region adjacent to the primary surface, a drain region adjacent to the drift region and extending deeper into the semiconductor layer as compared to the drift region, a resurf region spaced apart from the primary surface, an insulating layer overlying the drain region, and a contact extending through the insulating layer to the drain region. In an embodiment, the drain region can include a sinker region that allows a bulk breakdown to the resurf region to occur during an overvoltage event where the bulk breakdown occurs outside of the drift region, and in a particular embodiment, away from a shallow trench isolation structure or other sensitive structure.
1. An electronic device comprising a transistor structure, wherein the transistor structure comprises:
a buried conductive region having a first conductivity type;
a semiconductor layer overlying the buried conductive region, the semiconductor layer having a primary surface and a second conductivity type opposite the first conductivity type;
a drift region adjacent to the primary surface;
a sinker region contacting the drift region and extending deeper into the semiconductor layer as compared to the drift region;
a drain contact region spaced apart from the drift region;
a resurf region having the second conductivity type, wherein the resurf region is spaced apart from the primary surface, is spaced apart from the buried conductive region by a portion of the semiconductor layer, and extends under the drift region, wherein, within the transistor structure, none of the resurf region contacts the buried conductive region; and
a first trench isolation structure that extends from the primary surface to a depth in a range of 0.2 micron to 0.9 micron, wherein the first trench isolation structure overlies the resurf region.
2. The electronic device of claim 1 , further comprising a resurf extension region contacting the resurf region, wherein:
the drift region has a first side and a second side opposite the first side,
the sinker region is along the first side of the drift region and is spaced apart from the second side of the drift region, and
the resurf extension region is closer to the second side of the drift region than to the first side of the drift region.
3. The electronic device of claim 2 , further comprising a source region adjacent to the primary surface and overlying the resurf extension region.
4. The electronic device of claim 3 , further comprising a contact and a body contact region within the resurf extension region, wherein the contact contacts the body contact region and the source region.
5. The electronic device of claim 1 , further comprising:
a source region adjacent to the primary surface; and
a channel region disposed between the source region and the drift region,
wherein:
the resurf region underlies the channel region and has a peak concentration depth, and
the sinker region extends to a depth at least as deep as the peak concentration depth of the resurf region.
6. The electronic device of claim 5 , further comprising a gate electrode overlying the channel region and portions of the drift region and the first trench isolation structure.
7. The electronic device of claim 1 , further comprising:
an insulating layer overlying at least parts of the drift region and the sinker region; and
a contact extending through the insulating layer to the drain contact region.
8. The electronic device of claim 1 , wherein the buried conductive region underlies and contacts the sinker region.
9. The electronic device of claim 8 , further comprising a second trench isolation structure extending to a depth deeper than the buried conductive region.
10. The electronic device of claim 1 , wherein the transistor structure has a bulk breakdown voltage of at least 70 V.
11. The electronic device of claim 1 , wherein the transistor structure is configured such that, during a bulk breakdown, a location of highest impact ionization is located outside of the drift region.
12. The electronic device of claim 1 , further comprising:
a resurf extension region contacting the resurf region, wherein:
the drift region has a first side and a second side opposite the first side,
the sinker region is along the first side of the drift region and is spaced apart from the second side of the drift region, and
the resurf extension region is closer to the second side of the drift region than to the first side of the drift region;
a source region adjacent to the primary surface;
a channel region disposed between the source region and the drift region;
a gate electrode overlying at least a portion of each of the channel region, the drift region, and the first trench isolation structure; and
a second trench isolation structure that abuts the sinker region and extends to a depth deeper than the buried conductive region,
wherein the transistor structure has a bulk breakdown voltage of at least 70 V.
13. An electronic device comprising a transistor structure, wherein the transistor structure comprises:
a buried conductive region;
a semiconductor layer overlying the buried conductive region and having a primary surface;
a drift region adjacent to the primary surface;
a sinker region contacting the drift region and extending deeper into the semiconductor layer as compared to the drift region;
a resurf region spaced apart from the primary surface;
a resurf extension region adjacent to the resurf region;
a body contact region within the resurf extension region, wherein of the body contact region is electrically connected to the resurf region via the resurf extension region; and
a first trench isolation structure that extends from the primary surface to a depth in a range of 0.2 micron to 0.9 micron, wherein the first trench isolation structure overlies the resurf region,
wherein the transistor structure is configured such that a bulk breakdown occurs between the sinker portion and the resurf region.
14. The electronic device of claim 13 , further comprising:
a source region along the primary surface of the semiconductor layer and overlying the resurf extension region; and
a contact contacting the source region and the body contact region.
15. The electronic device of claim 13 , wherein the semiconductor layer includes a portion between the resurf region and the buried conductive region, such that the resurf region does not contact the buried conductive layer within the transistor structure.
16. The electronic device of claim 15 , wherein the bulk breakdown voltage is at least 70 V.
17. The electronic device of claim 16 , further comprising a second trench isolation structure extending to a depth deeper than the buried conductive region.
18. The electronic device of claim 15 , further comprising:
a source region adjacent to the primary surface;
a channel region disposed between the source region and the drift region;
a gate electrode overlying at least a portion of each of the source region, the channel region, the drift region, and the first trench isolation structure; and
a drain contact region within the sinker region and spaced apart from the drift region.