Gallium nitride materials and methods associated with the same
View Patent ↗Semiconductor materials including a gallium nitride material region and methods associated with such structures are provided. The semiconductor structures include a strain-absorbing layer formed within the structure. The strain-absorbing layer may be formed between the substrate (e.g., a silicon substrate) and an overlying layer. It may be preferable for the strain-absorbing layer to be very thin, have an amorphous structure and be formed of a silicon nitride-based material. The strain-absorbing layer may reduce the number of misfit dislocations formed in the overlying layer (e.g., a nitride-based material layer) which limits formation of other types of defects in other overlying layers (e.g., gallium nitride material region), amongst other advantages. Thus, the presence of the strain-absorbing layer may improve the quality of the gallium nitride material region which can lead to improved device performance.
1. A semiconductor structure comprising:
a silicon substrate having a top surface;
an amorphous silicon nitride-based material layer formed directly on a majority of the top surface of the substrate;
a nitride-based material overlying layer formed directly on the silicon nitride-based material layer; and
a gallium nitride material region formed over the overlying layer.
2. The structure of claim 1 , wherein the silicon nitride-based material layer is formed directly on the entire top surface of the substrate.
3. The structure of claim 1 , wherein the silicon nitride-based material layer comprises SiN.
4. The structure of claim 1 , wherein the overlying layer is a single crystal.
5. The structure of claim 1 , wherein the overlying layer is formed at temperatures of greater than about 700° C.
6. The structure of claim 1 , wherein the overlying layer comprises an aluminum nitride-based material.
7. The structure of claim 1 , wherein the overlying layer has an epitaxial relationship with the substrate.
8. The structure of claim 1 , wherein the overlying layer comprises a gallium nitride material alloy.
9. The structure of claim 1 , wherein the overlying layer is compositionally-graded.
10. The structure of claim 1 , further comprising a transition layer formed over the overlying layer.
11. The structure of claim 10 , wherein the transition layer is compositionally-graded.
12. The structure of claim 11 , wherein the compositionally-graded transition layer is formed directly on the overlying layer.
13. The structure of claim 11 , wherein the compositionally-graded transition layer comprises Al x Ga (1−x) N and x is decreased from a back surface of the transition layer to a front surface of the transition layer.
14. The structure of claim 1 , wherein the silicon nitride-based material layer has a thickness of less than 100 Angstroms.
15. The structure of claim 1 , wherein the silicon nitride-based material layer has a thickness of greater than 10 Angstroms.
16. The structure of claim 1 , wherein the silicon nitride-based material layer has a thickness between about 10 Angstroms and about 50 Angstroms.
17. The structure of claim 1 , wherein the substrate has a thickness of greater than about 125 micron.
18. The structure of claim 1 , wherein the gallium nitride material region includes a GaN layer.
19. The structure of claim 1 , wherein the overlying layer has a misfit dislocation density of less than about 10 10 defects/cm 2 .
20. The structure of claim 1 , wherein the structure is a FET.
21. The structure of claim 1 , wherein the entire top surface of the silicon nitride-based material layer has a uniform composition.
22. The structure of claim 21 , wherein the entire top surface of the strain-absorbing layer comprises Si x N y .
23. The structure of claim 1 , further comprising a source electrode, a gate electrode and a drain electrode formed on the gallium nitride material region.
24. A semiconductor structure comprising:
a silicon substrate including a top surface;
a silicon nitride-based material layer having a thickness of less than 100 Angstroms and formed directly on a majority of the top surface of the substrate; and
a single crystal aluminum nitride-based material overlying layer formed directly on the silicon nitride-based material layer; and
a gallium nitride material region formed over the overlying layer.
25. The structure of claim 24 , wherein the silicon nitride-based material layer has an amorphous structure.
26. The structure of claim 24 , wherein the silicon nitride-based material layer is formed directly on the entire top surface of the substrate.
27. The structure of claim 24 , further comprising a transition layer formed over the overlying layer.
28. The structure of claim 25 , wherein the transition layer is a compositionally-graded transition layer comprising Al x Ga (1−x) N and x is increased from a back surface of the transition layer to a front surface of the transition layer.
29. The structure of claim 24 , wherein the silicon nitride-based material layer has a thickness of greater than 10 Angstroms.
30. The structure of claim 24 , wherein the substrate has a thickness of greater than about 125 micron.
31. The structure of claim 24 , wherein the gallium nitride material region includes a GaN layer.
32. The structure of claim 24 , wherein the overlying layer has a misfit dislocation density of less than about at 10 10 defects/cm 2 .
33. The structure of claim 24 , wherein the entire top surface of the silicon nitride-based material layer has a uniform composition.
34. The structure of claim 33 , wherein the entire top surface of the strain-absorbing layer comprises Si x N y .
35. The structure of claim 24 , further comprising a source electrode, a gate electrode and a drain electrode formed on the gallium nitride material region.
36. A semiconductor structure comprising:
a silicon substrate including a top surface;
an amorphous silicon nitride-based material layer formed directly on the entire top surface of the silicon substrate and having a thickness of less than 100 Angstroms;
a nitride-based material overlying layer formed on the amorphous silicon nitride-based material layer; and
a gallium nitride material region formed on the overlying layer.
37. The structure of claim 36 , wherein the entire top surface of the silicon nitride-based material layer has a uniform composition.
38. The structure of claim 37 , wherein the entire top surface of the strain-absorbing layer comprises Si x N y .
39. The structure of claim 36 , further comprising a source electrode, a gate electrode and a drain electrode formed on the gallium nitride material region.
40. The structure of claim 36 , wherein the overlying layer is a single crystal.
41. The structure of claim 36 , wherein the overlying layer is formed at temperatures of greater than about 700° C.
42. The structure of claim 36 , wherein the overlying layer comprises an aluminum nitride-based material.
43. The structure of claim 36 , wherein the overlying layer has an epitaxial relationship with the substrate.
44. The structure of claim 36 , wherein the overlying layer comprises a gallium nitride material alloy.
45. The structure of claim 36 , wherein the silicon nitride-based material layer has a thickness of greater than 10 Angstroms.
46. The structure of claim 36 , wherein the silicon nitride-based material layer has a thickness between about 10 Angstroms and about 50 Angstroms.
47. The structure of claim 36 , wherein the gallium nitride material region includes a GaN layer.