Provided is an indium phosphide substrate, a semiconductor epitaxial wafer, and a method for producing an indium phosphide substrate, which can satisfactorily suppress warpage of the back surface of the substrate. The indium phosphide substrate includes a main surface for forming an epitaxial crystal layer and a back surface opposite to the main surface, wherein the back surface has a BOW value of −2.0 to 2.0 μm, as measured with the back surface of the indium phosphide substrate facing upward.

Provided is an indium phosphide substrate, a semiconductor epitaxial wafer, and a method for producing an indium phosphide substrate, which can satisfactorily suppress warpage of the back surface of the substrate. The indium phosphide substrate includes a main surface for forming an epitaxial crystal layer and a back surface opposite to the main surface, wherein the back surface has a BOW value of −2.0 to 2.0 μm, as measured with the back surface of the indium phosphide substrate facing upward.

A method of manufacturing a diamond substrate includes: forming an ion implantation layer at a side of a main surface of a diamond seed substrate by implanting ions into the main surface of the diamond seed substrate; producing a diamond structure by growing a diamond growth layer by a vapor phase synthesis method on the main surface of the diamond seed substrate, after implanting the ions; and performing heat treatment on the diamond structure. The performed heat treatment causes the diamond structure to be separated along the ion implantation layer into a first structure including the diamond seed substrate and failing to include the diamond growth layer, and a diamond substrate including the diamond growth layer. Thus, the method of manufacturing a diamond substrate is provided that enables a diamond substrate with a large area to be manufactured in a short time and at a low cost.

A method of manufacturing a diamond substrate includes: forming an ion implantation layer at a side of a main surface of a diamond seed substrate by implanting ions into the main surface of the diamond seed substrate; producing a diamond structure by growing a diamond growth layer by a vapor phase synthesis method on the main surface of the diamond seed substrate, after implanting the ions; and performing heat treatment on the diamond structure. The performed heat treatment causes the diamond structure to be separated along the ion implantation layer into a first structure including the diamond seed substrate and failing to include the diamond growth layer, and a diamond substrate including the diamond growth layer. Thus, the method of manufacturing a diamond substrate is provided that enables a diamond substrate with a large area to be manufactured in a short time and at a low cost.

A method for effectively removing minute impurities of 1 μm or less in size that are present on a surface of an aluminum nitride single-crystal substrate without etching the surface includes scrubbing a surface of an aluminum nitride single-crystal substrate using a polymer compound material having lower hardness than an aluminum nitride single crystal, and an alkali aqueous solution having 0.01-1 mass % concentration of potassium hydroxide or sodium hydroxide, the alkali aqueous solution being absorbed in the polymer compound material.

A method for effectively removing minute impurities of 1 μm or less in size that are present on a surface of an aluminum nitride single-crystal substrate without etching the surface includes scrubbing a surface of an aluminum nitride single-crystal substrate using a polymer compound material having lower hardness than an aluminum nitride single crystal, and an alkali aqueous solution having 0.01-1 mass % concentration of potassium hydroxide or sodium hydroxide, the alkali aqueous solution being absorbed in the polymer compound material.

In order to address the high recycling cost, high complexity and other problems encountered by the prior art, the present invention proposes a method for recycling a sapphire substrate, which is applicable to both patterned and smooth sapphire substrates and involves only two steps: high-temperature baking and high-temperature rinsing in a concentrated acid. It entails a simple process which can be completed with high efficiency in a short period by easy operations at significantly reduced cost.

In order to address the high recycling cost, high complexity and other problems encountered by the prior art, the present invention proposes a method for recycling a sapphire substrate, which is applicable to both patterned and smooth sapphire substrates and involves only two steps: high-temperature baking and high-temperature rinsing in a concentrated acid. It entails a simple process which can be completed with high efficiency in a short period by easy operations at significantly reduced cost.

A wafer manufacturing method, an epitaxial wafer manufacturing method, and a wafer and epitaxial wafer manufactured thereby, are provided. The wafer manufacturing method enables the manufacture of a wafer with a low density of micropipe defects and minimum numbers of particles and scratches. The epitaxial wafer manufacturing method enables the manufacture of an epitaxial wafer that has low densities of defects such as downfall, triangular, and carrot defects, exhibits excellent device characteristics, and improves the yield of devices.

A wafer manufacturing method, an epitaxial wafer manufacturing method, and a wafer and epitaxial wafer manufactured thereby, are provided. The wafer manufacturing method enables the manufacture of a wafer with a low density of micropipe defects and minimum numbers of particles and scratches. The epitaxial wafer manufacturing method enables the manufacture of an epitaxial wafer that has low densities of defects such as downfall, triangular, and carrot defects, exhibits excellent device characteristics, and improves the yield of devices.