Edge termination technique for high voltage power devices having a negative feature for an improved edge termination structure
Embodiments of a semiconductor die having a semiconductor device implemented on the semiconductor die and an edge termination structure around a periphery of the semiconductor device and methods of fabricating the same are disclosed. In one embodiment, a semiconductor die includes a semiconductor device and an edge termination structure around a periphery of the semiconductor device, where the edge termination structure includes negative features (e.g., trenches and/or divots) that vary dose in a corresponding edge termination region to approximate a desired dose profile. In one embodiment, the desired dose profile is a substantially decreasing or substantially linearly decreasing dose from an edge of a main junction of the semiconductor device to an edge of the edge termination region. In this manner, electric field crowding at the edge of the main junction of the semiconductor device is substantially reduced, which in turn substantially improves a break-down voltage of the semiconductor device.
1. A semiconductor die, comprising:
a semiconductor device; and
an edge termination structure in an edge termination region around a periphery of the semiconductor device, the edge termination structure comprising at least two negative features having at least two divot rings around the periphery of the semiconductor device wherein the at least two divot rings have increasing widths thereby providing a decreasing dose moving laterally toward an edge of the edge termination region.
2. The semiconductor die of claim 1 wherein the increasing widths of the divots approximate a desired dose profile from an edge of a main junction of the semiconductor device to the edge of the edge termination region.
3. A semiconductor die, comprising:
a semiconductor device; and
an edge termination structure in an edge termination region around a periphery of the semiconductor device, the edge termination structure approximating a desired dose profile from an edge of a main junction of the semiconductor device to an edge of the edge termination region and comprising:
one or more negative steps that define at least two concentric starting zones within the edge termination region; and
for each zone of the at least two concentric starting zones, at least two negative features in the zone that vary dose within the zone according to the desired dose profile, wherein, for at least one zone of the at least two concentric starting zones, the at least two negative features in the at least one zone comprise at least two trenches having increasing widths to thereby provide a decreasing dose moving laterally away from the edge of the main junction of the semiconductor device toward the edge of the edge termination region.
4. The semiconductor die of claim 3 wherein the desired dose profile is a linearly decreasing dose from the edge of the main junction of the semiconductor device to the edge of the edge termination region.
5. A semiconductor die, comprising:
a semiconductor device; and
an edge termination structure in an edge termination region around a periphery of the semiconductor device, the edge termination structure approximating a desired dose profile from an edge of a main junction of the semiconductor device to an edge of the edge termination region and comprising:
one or more negative steps that define at least two concentric starting zones within the edge termination region; and
for each zone of the at least two concentric starting zones, at least two negative features in the zone that vary dose within the zone according to the desired dose profile, wherein, for at least one zone of the at least two concentric starting zones, the at least two negative features in the at least one zone comprise at least two divot rings having increasing widths to thereby provide a decreasing dose moving laterally away from the edge of the main junction of the semiconductor device toward the edge of the edge termination region.
6. The semiconductor die of claim 5 wherein, for each zone of the at least one zone, divots within a divot ring of the at least two divot rings in the zone are all the same size, and a number of divots in each divot ring of the at least two divot rings in the zone is a function of the width of the divot ring.
7. The semiconductor die of claim 5 wherein, for each zone of the at least one zone, divots within different rings of the at least two divot rings in the zone are of varying sizes such that the sizes of the divots increase as the widths of the at least two divot rings increase.
8. The semiconductor die of claim 3 further comprising:
a first layer of a first doping type; and
a second layer of a second doping type;
wherein the semiconductor device comprises a first contact on a surface of the first layer opposite the second layer and a second contact on a surface of the second layer opposite the first layer, and the edge termination structure is formed in the second layer.
9. The semiconductor die of claim 3 wherein the semiconductor device is a vertical device.
10. The semiconductor die of claim 9 wherein the semiconductor device is a power device.
11. The semiconductor device of claim 10 wherein the semiconductor device is one of a group consisting of: a thyristor, a trench Insulated Gate Bipolar Transistor (trench-IGBT), a PiN diode, a Bipolar Junction Transistor (BJT), and a trench Junction Barrier Schottky (JBS) diode.
12. A method comprising:
forming a semiconductor device in a semiconductor die area of a semiconductor wafer; and
forming an edge termination structure around a periphery of the semiconductor device in an edge termination region within the semiconductor die area such that the edge termination structure approximates a desired dose profile from an edge of a main junction of the semiconductor device to an edge of the edge termination region;
wherein forming the edge termination structure comprises:
providing one or more negative steps in the edge termination region that define at least two concentric starting zones within the edge termination region; and
for each zone of the at least two concentric starting zones, providing at least two negative features in the zone that vary dose within the zone according to the desired dose profile wherein, for at least one zone of the at least two concentric starting zones, the at least two negative features in the at least one zone comprise at least two trenches having increasing widths to thereby provide a decreasing dose moving laterally away from the edge of the main junction of the semiconductor device toward the edge of the edge termination region.
13. The method of claim 12 wherein forming the edge termination structure comprises forming the edge termination structure such that the desired dose profile approximated by the edge termination structure is any desired dose profile.
14. The method of claim 12 wherein the desired dose profile is a substantially linearly decreasing dose from the edge of the main junction of the semiconductor device to the edge of the edge termination region.