Electronic device including a contact structure contacting a layer
An electronic device can include a semiconductor layer and a contact structure forming an ohmic contact with the layer. In an embodiment, the semiconductor layer can include a III-N material, and the contact structure includes a first phase and a second phase, wherein the first phase includes Al, the second phase includes a metal, and the first phase contacts the semiconductor layer. In another embodiment, the semiconductor layer can be a monocrystalline layer having a surface along a crystal plane. The contact structure can include a polycrystalline material including crystals having surfaces that contact the surface of the monocrystalline layer, wherein a lattice mismatch between the surface of the monocrystalline layer and the surfaces of the crystals is at most 20%.
1. An electronic device comprising:
a semiconductor layer, wherein:
the semiconductor layer is a monocrystalline layer including a III-N material having a hexagonal lattice structure, and
the monocrystalline layer has a surface along a (0002) crystal plane; and
a contact structure forming an ohmic contact with the semiconductor layer, wherein the contact structure includes a first phase and a second phase different from the first phase, wherein:
the first phase includes Al,
the second phase includes a metal,
the first phase includes first crystals having first surfaces that contact the surface of the monocrystalline layer, and
the first crystals have a cubic lattice structure, and the first surfaces of the crystals are along a (111) crystal plane.
2. The electronic device of claim 1 , wherein an interface between the semiconductor layer and the contact structure is free of an oxide.
3. The electronic device of claim 1 , wherein the second phase includes Al 3 Me, Me 2 AlN, MeN, or a combination thereof, wherein Me is the metal.
4. The electronic device of claim 3 , wherein the metal includes Ti, Zr, Hf, or Ta.
5. The electronic device of claim 3 , wherein the contact structure includes a first film in contact with the semiconductor layer, and Al rel % is at least 80%, wherein:
Al rel %=Al free /(Al total +Me total )*100%,
Al free % is the number of Al atoms/unit area in the first phase,
Al total is the total number of Al atoms/unit area in the contact structure, and
Me total is the total number of metal atoms/unit area in the contact structure.
6. The electronic device of claim 1 , wherein the contact structure comprises:
a first film in contact with the semiconductor layer and including the first and second phases; and
a capping film overlying the first film.
7. The electronic device of claim 1 , the contact structure contacts the semiconductor layer within a contact opening, and along a surface of the semiconductor layer within the contact opening, at least 1% of the surface of the semiconductor layer is in contact with the first phase of the conductive structure.
8. The electronic device of claim 1 , wherein the semiconductor layer includes In a Al b Ga c N where a+b+c=1, or a double heterostructure including a combination of different III-N compounds.
9. The electronic device of claim 1 , wherein the electronic device includes a high electron mobility transistor that includes the semiconductor layer and the contact structure.
10. The electronic device of claim 1 , wherein the electronic device has a plurality of contact structures having the same construction and an average contact resistance of at most 0.5 ohm*mm.
11. The electronic device of claim 1 , wherein:
the semiconductor layer includes Al (1-x) Ga x N where 0<x≤0.3,
the second phase contacts the semiconductor layer and includes Al 3 Me, wherein Me includes Ti, Zr, Hf, or Ta,
the contact structure includes a first film in contact with the semiconductor layer,
Al rel % is at least 80%, wherein:
Al rel %=Al free /(Al total +Me total )*100%,
Al free % is the number of Al atoms/unit area in the first phase,
Al total is the total number of Al atoms/unit area in the contact structure, and
Me total is the total number of metal atoms/unit area in the contact structure
the contact structure comprises:
a first film in contact with the semiconductor layer and including the first and second phases; and
a capping film overlying the first film, and
the electronic device includes a high electron mobility transistor that includes the semiconductor layer and the contact structure.
12. An electronic device comprising:
a semiconductor layer, wherein the semiconductor layer is a monocrystalline layer having a surface along a crystal plane; and
a contact structure forming an ohmic contact with the semiconductor layer, wherein the contact structure includes a first phase and a second phase different from the first phase, wherein:
the first phase includes Al,
the second phase includes a metal,
the first phase of the contact structure includes first crystals having first surfaces that contact the surface of the monocrystalline layer, and
a lattice mismatch between the surface of the monocrystalline layer and the first surfaces of the first crystals is at most 20%.
13. The electronic device of claim 12 , wherein the monocrystalline layer includes a III-N material.
14. The electronic device of claim 13 , wherein:
the III-N material has a hexagonal lattice structure, the surface of the monocrystalline layer is along a (0002) crystal plane, the first crystals have a cubic lattice structure, and the first surfaces of the crystals are along a (111) crystal plane.
15. The electronic device of claim 12 , wherein the first phase of the contact structure includes second crystals having second surfaces along a different crystal plane as compared to the first surfaces of the first crystals.
16. The electronic device of claim 12 , wherein the electronic device includes a high electron mobility transistor that includes the monocrystalline layer and the contact structure.
17. The electronic device of claim 12 , wherein:
the monocrystalline layer includes Al (1-x) Ga x N where 0<x≤0.3 and the surface is along a (0002) crystal plane,
the conductive structure includes a film having an Al phase and an Al 3 Me phase, wherein Me includes Ti, Zr, Hf, or Ta,
the Al phase includes the first crystals and second crystals, wherein the first surfaces of the first crystals are along a (111) crystal plane, and second surfaces of the second crystals are along a (200) crystal plane,
Al rel % is at least 80%, wherein:
Al rel %=Al free /(Al total +Me total )*100%,
Al free % is the number of Al atoms/unit area in the first phase,
Al total is the total number of Al atoms/unit area in the contact structure, and
Me total is the total number of metal atoms/unit area in the contact structure,
the contact structure comprises:
a first film in contact with the monocrystalline layer and including the first and second phases; and
a capping film overlying the first film,
the electronic device includes a high electron mobility transistor that includes the monocrystalline layer and the contact structure.
18. The electronic device of claim 1 , wherein the first phase includes at least 90 atomic % Al, and the second phase includes Al 3 Me, Me 2 AlN, MeN, or a combination thereof, wherein Me is Ti, Zr, Hf, or Ta.
19. An electronic device comprising:
a semiconductor layer, and
a contact structure including a first film in contact with the semiconductor layer and forming an ohmic contact with the semiconductor layer, wherein:
the first film includes a first phase and a second phase different from the first phase, wherein:
the first phase includes Al and contacts the semiconductor layer,
the second phase includes a metal, and
Al rel % is at least 80%, wherein:
Al rel %=Al free /(Al total +Me total )*100%,
Al free % is the number of Al atoms/unit area in the first phase,
Al total is the total number of Al atoms/unit area in the contact structure, and
Me total is the total number of metal atoms/unit area in the contact structure.
20. The electronic device of claim 19 , wherein the semiconductor layer includes In a Al b Ga c N, where a+b+c=1.