Process of forming an electronic device including a drift region, a sinker region and a resurf 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. A process of forming an electronic device comprising:
providing a workpiece including a semiconductor layer having a primary surface;
forming a drift region along the primary surface;
forming a resurf region within the semiconductor layer, wherein the resurf region is spaced apart from the primary surface;
forming a sinker region adjacent to the drift region and extending deeper into the semiconductor layer as compared to the drift region, wherein the sinker region has a higher dopant concentration as compared to the drift region;
forming a first 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 isolation structure overlies the resurf region;
forming a resurf extension region extending upward from a portion of the resurf region;
forming body and source contact regions in the semiconductor layer extending upward from the resurf extension region to the primary surface;
forming a patterned insulating layer defining a contact opening to the sinker region; and
forming a contact in the contact opening to the sinker region,
wherein a portion of the resurf region extends under a portion of the drift region and is in contact with the sinker region, and
wherein the sinker region has a dopant concentration in a range of 5×10 17 atoms/cm 3 to 1×10 20 atoms/cm 3 .
2. The process of claim 1 , wherein:
a channel region is disposed between the source contact region and the drift region;
a portion of the resurf region underlies the channel region and has a peak concentration depth; and
the sinker region includes a sinker portion that extends to a depth at least as deep as the peak concentration depth of the resurf region.
3. The process of claim 2 , further comprising forming a buried conductive region before forming the semiconductor layer, wherein forming the sinker region is performed such that the sinker portion extends to the buried conductive region.
4. The process of claim 2 , further comprising forming a buried conductive region before forming the semiconductor layer, wherein forming the sinker region is performed such that the sinker portion is spaced apart from the buried conductive region.
5. The process of claim 2 , further comprising forming a second isolation structure that abuts the sinker portion of the sinker region and extends to a depth deeper than the sinker portion.
6. The process of claim 5 , further comprising:
forming the first isolation structure extending into the drift region and having a depth less than the drift region; and
forming a gate electrode over the channel region and portions of the drift region and first isolation structure.
7. The process of claim 2 , wherein the sinker portion extends deeper into the semiconductor layer as compared to the peak concentration depth of the resurf region.
8. The process of claim 1 , wherein a transistor includes a portion of the semiconductor layer, the drift region, the sinker region, the resurf region, and a source region, wherein the transistor has a bulk breakdown voltage of at least 70 V.
9. The process of claim 1 , further comprising forming a shield electrode over the drift region.
10. The process of claim 1 , wherein the drift region has a dopant concentration in a range of 1×10 15 atoms/cm 3 to 1×10 18 atoms/cm 3 .
11. The process of claim 1 , wherein only the drift region is disposed between the first isolation structure and the resurf region.
12. The process of claim 1 , wherein the drift region abuts the first isolation structure and the sinker portion.
13. A process of forming an electronic device comprising:
providing a workpiece including a semiconductor layer having a primary surface;
forming a drift region along the primary surface;
forming a resurf region within the semiconductor layer, wherein the resurf region is spaced apart from the primary surface, and an uppermost surface of the resurf region contacts the drift region;
forming a sinker region adjacent to the drift region and extending deeper into the semiconductor layer as compared to the drift region, wherein the sinker region has a dopant concentration in a range of 5×10 17 atoms/cm 3 to 1×10 20 atoms/cm 3 ;
forming a first 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 isolation structure overlies a portion of the resurf region;
forming a resurf extension region extending upward from a portion of the resurf region;
forming body and source contact regions in the semiconductor layer extending upward from the resurf extension region to the primary surface;
forming a drain contact region adjacent to the sinker region and spaced apart from the drift region;
forming a patterned insulating layer defining a contact opening to the drain contact region; and
forming a contact in the contact opening to the drain contact region,
wherein a portion of the resurf region is in contact with the sinker region.
14. The process of claim 13 , wherein the drift region has a dopant concentration in a range of 1×10 15 atoms/cm 3 to 1×10 18 atoms/cm 3 .
15. The process of claim 14 , wherein the sinker region has a higher dopant concentration as compared to the drift region.
16. The process of claim 13 , wherein the first isolation structure abuts the drift region and the sinker portion.
17. The process of claim 13 , wherein the drift region lies along an uppermost surface of the resurf region contacting the drift region.