Gallium nitride material structures including substrates and methods associated with the same
View Patent ↗Gallium nitride material-based semiconductor structures are provided. In some embodiments, the structures include a composite substrate over which a gallium nitride material region is formed. The gallium nitride material structures may include additional features, such as strain-absorbing layers and/or transition layers, which also promote favorable stress conditions. The reduction in stresses may reduce defect formation and cracking in the gallium nitride material region, as well as reducing warpage of the overall structure. The gallium nitride material-based semiconductor structures may be used in a variety of applications such as transistors (e.g. FETs) Schottky diodes, light emitting diodes, laser diodes, SAW devices, and sensors, amongst others devices.
1. A gallium nitride material semiconductor structure comprising:
a composite substrate comprising a silicon surface layer and a lower portion on which the substrate is formed, the surface layer having a thickness of less than 10.0 microns, wherein the substrate has a diameter of at least 100 mm; and
a gallium nitride material region formed over the composite having a thickness of greater than 2.0 microns,
wherein the structure has a warp of less than 250 micron.
2. The structure of claim 1 , wherein the surface layer has a thickness of between 0.1 micron and 10.0 microns.
3. The structure of claim 1 , wherein the thickness of the gallium nitride material region is within an order of magnitude of the thickness of the surface layer.
4. The structure of claim 1 , wherein the lower portion has a thickness of greater than at least 10 times the thickness of the silicon layer.
5. The structure of claim 1 , wherein the lower portion comprises a polycrystalline material.
6. The structure of claim 1 , further comprising a silicon nitride-based layer formed directly on the substrate.
7. The structure of claim 6 , wherein the silicon nitride-based layer has an amorphous crystal structure and a thickness of less than 100 Angstroms.
8. The structure of claim 1 , further comprising a transition layer formed over the substrate, wherein the transition layer comprises a gallium nitride alloy and a gallium concentration in the transition layer increases from a back surface to a top surface of the transition layer.
9. The structure of claim 1 , wherein the gallium nitride material region has a misfit dislocation density of less than 10 10 defects/cm 2 .
10. The structure of claim 1 , wherein the gallium nitride material region includes more than one gallium nitride material layer.
11. The structure of claim 1 , wherein the substrate is selected from the group consisting of silicon-on-insulator, silicon-on-poly SiC, and silicon-on-poly AlN.
12. A gallium nitride material semiconductor structure comprising:
a substrate comprising silicon and having a diameter of at least 100 mm; and
a gallium nitride material region formed over the substrate having a thickness of greater than 2.0 micron,
wherein the structure has a warp of less than 500 micron.
13. The structure of claim 12 , wherein the substrate is a composite substrate that comprises a silicon layer at a top surface of the substrate.
14. The structure of claim 13 , wherein the composite substrate includes a lower portion on which the silicon layer is formed, the lower portion having a thickness of greater than at least 10 times the thickness of the silicon layer.
15. The structure of claim 12 , further comprising a silicon nitride-based layer formed directly on the substrate having a thickness of less than 100 Angstroms; and, a transition layer formed over the substrate, wherein the transition layer comprises a gallium nitride alloy and a gallium concentration in the transition layer increases from a back surface to a top surface of the transition layer.
16. A gallium nitride material semiconductor structure comprising:
a substrate comprising silicon and having a diameter of at least about 150 mm; and
a gallium nitride material region formed over the substrate having a thickness of greater than 1.5 micron,
wherein the structure has a warp of less than 500 micron.
17. The structure of claim 16 , wherein the substrate has a warp of less than 250 micron.
18. The structure of claim 16 , wherein the substrate is a composite substrate comprising a silicon layer at a top surface of the substrate.
19. The structure of claim 16 , wherein the substrate has a warp of less than 250 micron.