High surface quality GaN wafer and method of fabricating same
AssigneeCree, Inc.
InventorsXueping Xu, Robert P. Vaudo
Life of this patent
Estimating the term…
Abstract
AlxGayInzN, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1, characterized by a root mean square surface roughness of less than 1 nm in a 10×10 μm2 area. The AlxGayInzN may be in the form of a wafer, which is chemically mechanically polished (CMP) using a CMP slurry comprising abrasive particles, such as silica or alumina, and an acid or a base. High quality AlxGayInzN wafers can be fabricated by steps including lapping, mechanical polishing, and reducing internal stress of said wafer by thermal annealing or chemical etching for further enhancement of its surface quality. CMP processing may be usefully employed to highlight crystal defects of an AlxGayInzN wafer.
Claims91
A wafer comprising AlxGayInzN, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1 and x+y+z=1, characterized by a root mean square (RMS) surface roughness of less than 1 nm in a 10×10 μm2 area on a wafer surface thereof, wherein the wafer surface is selected from the group consisting of:
- AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of N-terminated surfaces of AlxGayInzN in an (0001) orientation, A-plane surfaces, M-plane surfaces, R-plane surfaces, offcuts of A-plane surfaces, offcuts of M-plane surfaces, and offcuts of R-plane surfaces.
An epitaxial AlxGayInzN crystal structure, comprising an epitaxial Alx′Gay′Inz′N thin film grown on a wafer comprising AlxGayInzN, wherein 0≦x′≦1, 0≦y′≦1, 0≦z′≦1, x′+y′+z′=1, 0≦x≦1, 0≦y≦1, 0≦z≦1, said wafer being characterized by a root mean square (RMS) surface roughness of less than 1 nm in a 10×10 μm2 area on a surface thereof, wherein the wafer surface is selected from the group consisting of:
- AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of N-terminated surfaces of AlxGayInzN in an (0001) orientation, A-plane surfaces, M-plane surfaces, R-plane surfaces, offcuts of A-plane surfaces, offcuts of M-plane surfaces and offcuts of R-plane surfaces.
An optoelectronic device comprising at least one epitaxial Alx′Gay′Inz′N crystal structure grown on a wafer comprising AlxGayInzN, wherein 0≦x′≦1, 0≦y′≦1, 0≦z′≦1, x′+y′+z′=1, 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1, said wafer being characterized by a root mean square (RMS) surface roughness of at least less than 1 nm in a 10×10 μm2 area on a wafer surface thereof, wherein the wafer surface is selected from the group consisting of:
- AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of N-terminated surfaces of AlxGayInzN in an (0001) orientation, A-plane surfaces, M-plane surfaces, R-plane surfaces, offcuts of A-plane surfaces, offcuts of M-plane surfaces, and offcuts of R-plane surfaces.
A microelectronic device comprising at least one epitaxial Alx′Gay′Inz′N crystal structure grown on a wafer comprising AlxGayInzN, wherein 0≦x′≦1, 0≦y′≦1, 0≦z′≦1, x′+y′+z′=1, 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1, said wafer being characterized by a root mean square (RMS) surface roughness of at least less than 1 nm in a 10×10 μm2 area on a wafer surface thereof, wherein the wafer surface is selected from the group consisting of:
- AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of N-terminated surfaces of AlxGayInzN in an (0001) orientation, A-plane surfaces, M-plane surfaces, R-plane surfaces, offcuts of A-plane surfaces, offcuts of M-plane surfaces and offcuts of R-plane surfaces.
An epitaxial Alx′Gay′Inz′N crystal boule grown on a wafer comprising AlxGayInzN, 0≦x′≦1, 0≦y′≦1, 0≦z′≦1, x′+y′+z′=1, 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1, said wafer being characterized by a root mean square (RMS) surface roughness of at least less than 1 nm in a 10×10 μm2 area on a wafer surface thereof, wherein the wafer surface is selected from the group consisting of:
- AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of N-terminated surfaces of AlxGayInzN in an (0001) orientation, A-plane surfaces, M-plane surfaces, R-plane surfaces, offcuts of A-plane surfaces, offcuts of M-plane surfaces, and offcuts of R-plane surfaces.
A method of chemically mechanically polishing (CMP) an AlxGayInzN wafer, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1, characterized by a root mean square (RMS) surface roughness of less that 1 nm in a 10×10 μm2 area on a wafer surface thereof, wherein the wafer surface is selected from the group consisting of:
- AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of N-terminated surfaces of AlxGayInzN in an (0001) orientation, A-plane surfaces, M-plane surfaces, R-plane surfaces, offcuts of A-plane surfaces, offcuts of M-plane surfaces and offcuts of R-plane surfaces, using a CMP slurry comprising:
- abrasive amorphous silica particles;
- at least one acid;
- and
- optionally, at least one oxidation agent;
- wherein the CMP slurry has an acidic pH.
A method of chemically mechanically polishing an AlxGayInzN wafer, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1, characterized by a root mean square (RMS) surface roughness of less that 1 nm in a 10×10 μm2 area on a wafer surface thereof, wherein the wafer surface is selected from the group consisting of:
- AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of N-terminated surfaces of AlxGayInzN in an (0001) orientation, A-plane surfaces, M-plane surfaces, R-plane surfaces, offcuts of A-plane surfaces, offcuts of M-plane surfaces and offcuts of R-plane surfaces, using a CMP slurry comprising:
- abrasive colloidal alumina particles;
- at least one acid;
- and
- optionally, at least one oxidation agent;
- wherein the CMP slurry has an acidic pH.
A method of chemically mechanically polishing an AlxGayInzN wafer, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1, characterized by a root mean square (RMS) surface roughness of less that 1 nm in a 10×10 μm2 area on a wafer surface thereof, wherein the wafer surface is selected from the group consisting of:
- AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of N-terminated surfaces of AlxGayInzN in an (0001) orientation, A-plane surfaces, M-plane surfaces, R-plane surfaces, offcuts of A-plane surfaces, offcuts of M-plane surfaces and offcuts of R-plane surfaces, using a CMP slurry comprising:
- amorphous silica particles;
- at least one base;
- and
- optionally, at least one oxidization agent,
- wherein the CMP slurry has a basic pH.
The method claim of 26, wherein the CMP slurry is filtered to remove particles larger than 100 nm in diameter before delivery to the polishing pad.
The method claim of 34, wherein the CMP slurry is filtered to remove particles larger than 100 nm in diameter before delivery to the polishing pad.
The method claim of 40, wherein the CMP slurry is filtered to remove particles larger than 100 nm in diameter before delivery to the polishing pad.
A method of determining crystal defect density in an AlxGayInzN wafer, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1, characterized by a root mean square (RMS) surface roughness of less that 1 nm in a 10×10 μm2 area on a wafer surface thereof, wherein the wafer surface is selected from the group consisting of:
- AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of N-terminated surfaces of AlxGayInzN in an (0001) orientation, A-plane surfaces, M-plane surfaces, R-plane surfaces, offcuts of A-plane surfaces, offcuts of M-plane surfaces and offcuts of R-plane surfaces, comprising the steps of:
- providing an AlxGayInzN wafer;
- chemically mechanically polishing said wafer, using a CMP slurry comprising abrasive amorphous silica articles, at least one acid, and optionally at least one oxidization agent, wherein said CMP slurry has an acidic pH;
- cleaning and drying the polished AlxGayInzN wafer;
- and
- scanning the wafer with an atomic force microscope or a scanning electron microscope to determine defect density in said wafer.
A method of fabricating wafers comprising AlxGayInzN, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1, comprising the steps of:
- providing an AlxGayInzN wafer blank having thickness in a range from about 100μm to about 1000μm;
- optionally, reducing the internal stress of the AlxGayInzN wafer blank;
- optionally, lapping the AlxGayInzN wafer blank at a back side thereof, using a lapping slurry comprising abrasives having an average particle size in a range of from about 5 μm to about 15 μm;
- optionally, mechanically polishing the AlxGayInzN wafer blank at the back side thereof, using a mechanical polishing slurry comprising abrasives having average particle size in a range of from about 0.1 μm to about 6 μm;
- optionally, lapping the AlxGayInzN wafer blank at a front side thereof, using a lapping slurry comprising abrasives having an average particle size in a range of from about 5 μm to about 15 μm;
- optionally, mechanically polishing the AlxGayInzN wafer blank at the front side thereof, using a mechanical polishing slurry comprising abrasives having average particle size in a range of from about 0.1μm to about 6 μm;
- chemically mechanically polishing the AlxGayInzN wafer at the front side thereof, using a CMP slurry comprising at least one chemical reactant and abrasive particles having average particle size of less than 200 nm;
- and
- optionally, etching the AlxGayInzN wafer in a mild etching condition to further reduce internal stresses of the AlxGayInzN wafer, to improve surface quality, and to produce a matte finish at the back side of the wafer,
- wherein the AlxGayInzN wafer so fabricated has a surface roughness characterized by a root mean square (RMS) surface roughness of less than 1 nm in a 10×10 μm2 area at the front side of the wafer, wherein the wafer surface is selected from the group consisting of:
- AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of N-terminated surfaces of AlxGayInzN in an (0001) orientation, A-plane surfaces, M-plane surfaces, R-plane surfaces, offcuts of A-plane surfaces, offcuts of M-plane surfaces and offcuts of R-plane surfaces.
The method claim of 58, where the AlxGayInzN boule is sliced so that the wafer blank surface is perpendicular to the c-axis.
The method claim of 58, where the AlxGayInzN boule is sliced so that the wafer blank surface comprises a surface selected from the group consisting of:
- AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation;
- offcuts of AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation;
- offcuts of N-terminated surfaces of AlxGayInzN in an (0001) orientation;
- A-plane surfaces;
- M-plane surfaces;
- R-plane surfaces;
- offcuts of A-plane surfaces;
- offcuts of M-plane surfaces;
- and offcuts of R-plane surfaces.
The method claim of 56, wherein the mild etching condition is selected from the group consisting of etching in aqueous acid solution and etching in aqueous base solution at a temperature below 100° C.
The method claim of 78, wherein the acid is selected from group consisting of aqueous hydrofluoric acid, nitric acid, sulfuric acid, phosphoric acid, and combinations thereof.
The method claim of 78, wherein the base is selected from group consisting of aqueous LiOH, NaOH, KOH, RbOH, CsOH, and combinations thereof.
An AlxGayInzN crystal, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1, characterized by a root mean square (RMS) surface roughness of less than 1 nm in a 10×10 μm2 area on a surface thereof, and said surface is selected from the group consisting of:
- AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation;
- offcuts of AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation;
- offcuts of N-terminated surfaces of AlxGayInzN in an (0001) orientation;
- A-plane surfaces;
- M-plane surfaces;
- R-plane surfaces;
- offcuts of A-plane surfaces;
- offcuts of M-plane surfaces;
- and offcuts of R-plane surfaces.
A method of fabricating a laser facet on an article formed of AlxGayInzN, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1, comprising chemically mechanically polishing said article at a surface thereof using a chemical mechanical polishing slurry including silica and/or alumina abrasive particles, and an acid or base, wherein said chemically mechanically polishing step is carried out to impart to said surface a root mean square (RMS) surface roughness of less than 1 nm in a 10×10 μm2 area thereof, wherein the wafer surface is selected from the group consisting of:
- AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of N-terminated surfaces of AlxGayInzN in an (0001) orientation, A-plane surfaces, M-plane surfaces, R-plane surfaces, offcuts of A-plane surfaces, offcuts of M-plane surfaces and offcuts of R-plane surfaces.
A method of chemically mechanically polishing AlxGayInzN, wherein 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z=1, using a chemical mechanical polishing slurry including silica and/or alumina abrasive particles, and an acid or base, wherein the chemically mechanically polishing step is carried out to impart to the surface a root mean square (RMS) surface roughness of less than 1 nm in a 10×10 μm2 area thereof, characterized by a root mean square (RMS) surface roughness of less than 1 nm in a 10×10 μm2 area thereof, wherein the wafer surface is selected from the group consisting of:
- AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of N-terminated surfaces of AlxGayInzN in an (0001) orientation, A-plane surfaces, M-plane surfaces, R-plane surfaces, offcuts of A-plane surfaces, offcuts of M-plane surfaces and offcuts of R-plane surfaces.
A GaN crystal film, characterized by a root mean square (RMS) surface roughness of less than 1 nm in a 10×10 μm2 area on a surface thereof, and said surface is selected from the group consisting of:
- Ga-terminated surfaces of GaN in an (0001) orientation;
- offcuts of Ga-terminated surfaces of GaN in an (0001) orientation;
- offcuts of N-terminated surfaces of GaN in an (0001) orientation;
- A-plane surfaces;
- M-plane surfaces;
- R-plane surfaces;
- offcuts of A-plane surfaces;
- offcuts of M-plane surfaces;
- and offcuts of R-plane surfaces.
A method of chemically mechanically polishing GaN, using a chemical mechanical polishing slurry including silica and/or alumina abrasive particles, and an acid or base, wherein the chemically mechanically polishing step is carried out to impart to the surface a root mean square (RMS) surface roughness of less than 1 nm in a 10×10 μm2 area thereof, wherein the surface is selected from the group consisting of:
- AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of AlxGayInz-terminated surfaces of AlxGayInzN in an (0001) orientation, offcuts of N-terminated surfaces of AlxGayInzN in an (0001) orientation, A-plane surfaces, M-plane surfaces, R-plane surfaces, offcuts of A-plane surfaces, offcuts of M-plane surfaces and offcuts of R-plane surfaces.
Dependencies are inferred from the claim text.