Thin film and substrate-removed group III-nitride based devices and method
A method of thinning a bulk aluminum nitride substrate includes providing a bulk aluminum nitride (AlN) substrate with at least one epitaxially grown group-III-nitride layer on a first side of the substrate, applying a slurry having a high pH to a second side of the substrate opposite the first side, chemical mechanically polishing the second side of the substrate using the slurry to remove at least a portion of the substrate, resulting in a thinned layer with a thickness less than 50 microns, and bonding the epitaxial layer to a non-native substrate. A device has at least one active zone in a layer of epitaxial Group-III-nitride material, the epitaxial Group-III-nitride layer having a defect density of less than or equal to 10 8 /cm 2 .
1. A method of thinning a bulk aluminum nitride substrate, comprising:
providing a bulk aluminum nitride (AlN) substrate with at least one epitaxially grown group-III-nitride layer on a first side of the substrate;
applying a slurry having a high pH to a second side of the substrate opposite the first side;
chemical mechanically polishing the second side of the substrate using the slurry to remove at least a portion of the substrate, resulting in a thinned layer with a thickness less than 50 microns; and
bonding the epitaxial layer to a non-native substrate.
2. The method of claim 1 , wherein the slurry has a pH in the base range.
3. The method of claim 1 , wherein the slurry includes abrasive particles.
4. The method of claim 1 , wherein polishing the second side of the substrate comprises to remove at least a portion of the substrate comprises removing the entire substrate.
5. The method of claim 1 , wherein providing the substrate with at least one epitaxially grown group-III-nitride layer comprises providing the substrate with at least one epitaxially grown group-III-nitride layer having a threading dislocation density in a range of less than 10 8 /cm 2 .
6. The method of claim 1 , wherein providing the substrate with at least one epitaxially grown Group-III-nitride layer comprises growing the epitaxial Group-III-nitride layer to a thickness dependent upon a total thickness variation obtainable by bonding, thinning and polishing.
7. The method of claim 1 , wherein providing the substrate with at least one epitaxially grown Group-III-nitride layer comprises growing the epitaxial Group-III-nitride layer to a thickness of at least 10 microns.
8. The method of claim 1 , further comprising forming at least one light emitting heterostructure in the epitaxial layer.
9. The method of claim 1 , further comprising bonding the substrate to a carrier prior to applying the slurry.
10. The method of claim 9 , further comprising debonding the epitaxial Group-III-nitride layer from the carrier after the polishing.
11. The method of claim 1 , wherein bonding the epitaxial Group-III-nitride layer to a non-native substrate comprises at least one of direct bonding, surface treatments, interlayer deposition, pressure bonding, heat bonding, adhesive bonding, metal eutectic bonding, metal-metal bonding, and anodic bonding.
12. The method of claim 1 , wherein polishing the second side of the substrate comprises polishing the substrate to remove the entire substrate.
13. The method of claim 1 , wherein polishing the second side of the substrate comprises polishing the substrate to thin the substrate.
14. The method of claim 1 , wherein the thinned layer comprises one of a thinned epitaxial layer, or a thinned layer consisting of the epitaxial layer and the substrate.