Electric Field Modification for Nitrogen-Polar Group III-Nitride Semiconductor Devices
Semiconductor devices having nitrogen-polar (N-polar) Group III-nitride semiconductor structures are provided. In one example, a semiconductor device may include a nitrogen polar (N-polar) Group III-nitride semiconductor structure. The N-polar Group III-nitride semiconductor structure may have a first surface and a second surface opposing the first surface. The semiconductor device may include an electrode. The semiconductor device may include a low-k dielectric layer located between the first surface of the N-polar Group III-nitride semiconductor structure and at least a portion of the electrode. The low-k dielectric layer may have a dielectric constant of less than about 3.9. In some examples, the N-polar Group III-nitride semiconductor structure may include a trench extending at least partially into one or more cap layers of the N-polar Group III-nitride semiconductor structure.
1 . A semiconductor device, comprising:
a nitrogen polar (N-polar) Group III-nitride semiconductor structure, the N-polar Group III-nitride semiconductor structure having a first surface and a second surface opposing the first surface;
an electrode;
a low-k dielectric layer located between the first surface of the N-polar Group III-nitride semiconductor structure and at least a portion of the electrode; and
wherein the low-k dielectric layer has a dielectric constant of less than about 3.9.
2 . The semiconductor device of claim 1 , wherein the dielectric constant of the low-k dielectric layer is greater than 1.
3 . The semiconductor device of claim 1 , wherein the low-k dielectric layer comprises one or more of a doped silicon dioxide, a porous silicon dioxide, an organic material, or a silicon-based polymeric material.
4 . The semiconductor device of claim 1 , wherein the electrode comprises a first portion on the N-polar Group III-nitride semiconductor structure and a second portion on the first portion, the first portion extending generally perpendicular to the first surface of the N-polar Group III-nitride semiconductor structure and the second portion extending generally parallel to the first surface of the N-polar Group III-nitride semiconductor structure.
5 . The semiconductor device of claim 4 , wherein the first portion of the electrode extends into the N-polar Group III-nitride semiconductor structure.
6 . The semiconductor device of claim 4 , the second portion of the electrode is spaced apart from the first portion of the N-polar Group III-nitride semiconductor structure.
7 . The semiconductor device of claim 6 , wherein the low-k dielectric layer contacts the second portion of the electrode.
8 . The semiconductor device of claim 6 , wherein the low-k dielectric layer fills a space defined between the first surface of the N-polar Group III-nitride semiconductor structure and the second portion of the electrode.
9 . The semiconductor device of claim 1 , wherein the electrode is a gate contact, wherein the gate contact is a T-gate contact or a gamma-gate contact.
10 . (canceled)
11 . The semiconductor device of claim 1 , wherein the semiconductor device further comprises a second dielectric layer between the low-k dielectric layer and the N-polar Group III-nitride structure.
12 . The semiconductor device of claim 11 , wherein the second dielectric layer comprises silicon nitride.
13 . The semiconductor device of claim 11 , wherein the low-k dielectric layer fills a space defined between the second dielectric layer and at least portion of the electrode.
14 . The semiconductor device of claim 1 , wherein the Group III-nitride semiconductor structure comprises a barrier layer, a channel layer, and one or more cap layers, wherein the Group III-nitride semiconductor structure comprises a trench extending at least partially into the one or more cap layers.
15 . The semiconductor device of claim 14 , wherein the trench has a lateral width extending between a gate contact and a drain contact.
16 . The semiconductor device of claim 15 , wherein the lateral width is about 50% or greater of a distance between the gate contact and the drain contact.
17 . The semiconductor device of claim 15 , wherein the trench extends to a depth from the first surface of about 250 Angstroms to about 1000 Angstroms.
18 . (canceled)
19 . The semiconductor device of claim 1 , wherein the semiconductor device comprises a silicon carbide substrate.
20 . The semiconductor device of claim 1 , wherein the semiconductor device is a high electron mobility transistor device.
21 . A transistor device, comprising:
a nitrogen polar (N-polar) Group III-nitride semiconductor structure, the N-polar Group III-nitride semiconductor structure comprising:
a barrier layer;
a channel layer on the barrier layer; and
one or more cap layers on the channel layer; and
wherein the transistor device comprises a trench extending at least partially into the one or more cap layers of the N-polar Group III-nitride semiconductor structure.
22 .- 56 . (canceled)
57 . A method, comprising:
forming an N-polar Group III-nitride semiconductor structure;
forming a gate contact on the N-polar Group III-nitride semiconductor structure; and
forming a low-k dielectric layer in a space between the N-polar Group III-nitride semiconductor structure and at least a portion of the gate contact; and
wherein the low-k dielectric layer has a dielectric constant of less than about 3.9.
58 .- 71 . (canceled)