III-nitride device passivation and method
View Patent ↗An embodiment of a III-nitride semiconductor device and method for making the same may include a low resistive passivation layer that permits the formation of device contacts without damage to the III-nitride material during high temperature processing. The passivation layer may be used to passivate the entire device. The passivation layer may also be provided in between contacts and active layers of the device to provide a low resistive path for current conduction. The passivation process may be used with any type of device, including FETs, rectifiers, schottky diodes and so forth, to improve breakdown voltage and prevent field crowding effects near contact junctions. The passivation layer may be activated with a low temperature anneal that does not impact the III-nitride device regarding outdiffusion.
1. A III-nitride semiconductor device, comprising:
a conduction channel formed at an interface between two III-nitride layers having different lattice constants;
a gate contact;
an electrode coupled to the channel to carry channel current;
a protective layer under the electrode; and
another protective layer under the gate contact, the another protective layer comprising highly doped GaN.
2. The device according to claim 1 , wherein the III-nitride layers are composed of GaN and AlGaN, respectively.
3. The device according to claim 1 , wherein the electrode is an ohmic contact.
4. The III-nitride semiconductor device of claim 1 , wherein said protective layer comprises highly doped GaN.
5. The III-nitride semiconductor device of claim 1 , wherein said III-nitride semiconductor device comprises a high electron mobility transistor (HEMT).
6. A III-nitride semiconductor device, comprising:
a heterojunction including a first III-nitride semiconductor layer and a second III-nitride semiconductor layer formed over said first III-nitride semi conductor layer;
an opening extending through said second III-nitride semiconductor layer to said first III-nitride semiconductor layer;
a protective layer formed in said opening, said protective layer formed on said first III-nitride semi conductor layer;
an electrode formed on said protective layer, said electrode coupled to a conductive channel of said first semiconductor layer through said protective layer.
7. The III-nitride semiconductor device of claim 6 , wherein said first III-nitride semiconductor layer comprises gallium nitride (GaN).
8. The III-nitride semiconductor device of claim 6 , wherein said second III-nitride semiconductor layer comprises aluminum gallium nitride (AlGaN).
9. The III-nitride semiconductor device of claim 6 , wherein said protective layer comprises highly doped GaN.
10. The III-nitride semiconductor device of claim 6 , wherein said electrode makes ohmic contact with said first III-nitride semiconductor layer through said protective layer.
11. The III-nitride semiconductor device of claim 6 , further comprising a gate formed over said second III-nitride semiconductor layer.
12. The III-nitride semiconductor device of claim 11 , further comprising another protective layer formed between said gate and said second III-nitride semiconductor layer.
13. The III-nitride semiconductor device of claim 12 , wherein said another protective layer comprises highly doped GaN.
14. The III-nitride semiconductor device of claim 6 , wherein said III-nitride semiconductor device comprises a high electron mobility transistor (HEMT).