There is provided a method for manufacturing a nitride-based high electron mobility transistor, including: providing a conductive member on a nitride semiconductor crystal substrate, outside an element region in a plan view; forming a mask on the substrate, the mask having an opening in at least one of a source recess etching region and a drain recess etching region; performing photoelectrochemical etching by irradiating the substrate with light to form at least one of a source recess and a drain recess, in a state where the substrate on which the conductive member is provided and the mask is formed is in contact with an etching solution containing an oxidizing agent that receives electrons; and forming an element separation structure of the high electron mobility transistor.

There is provided a method for manufacturing a structure, including:

applying a first etching to a surface of a member, at least the surface being composed of Group III nitride; and applying a second etching to the surface to which the first etching has been applied, wherein in applying the first etching, a flat portion and a protruding portion are formed, the flat portion being newly appeared on the surface by etching, and the protruding portion being raised with respect to the flat portion, which is caused by being less likely to be etched than the flat portion, and in applying the second etching, the protruding portion is lowered by etching the protruding portion.

A method for the reuse of gallium nitride (GaN) epitaxial substrates uses band-gap-selective photoelectrochemical (PEC) etching to remove one or more epitaxial layers from bulk or free-standing GaN substrates without damaging the substrate, allowing the substrate to be reused for further growth of additional epitaxial layers. The method facilitates a significant cost reduction in device production by permitting the reuse of expensive bulk or free-standing GaN substrates.

Methods for wet-etching semiconductor samples and devices fabricated from the same are disclosed. The methods can be for selectively wet-etching a semiconductor sample comprising selecting a liquid-phase solution such that when the semiconductor sample is etched with the liquid-phase solution, at least a portion of one of a first doped region or a second doped region is etched at a greater rate than at least a portion of the other of the first doped region or the second doped region; and wet-etching, with the liquid-phase solution, the at least a portion of one of the first doped region or the second doped region at a first etch rate and the at least a portion of the other of the first doped region or the second doped region at a second etch rate; wherein the first etch rate can be greater than the second etch rate.

A process of preparing a wafer having a diameter of two inches or more, at least a surface of the wafer being formed from a group III nitride crystal, including preparing an alkaline or acidic etching liquid containing a peroxodisulfate ion as an oxidizing agent that accepts an electron, accommodating the wafer such that the surface of the wafer is immersed in the etching liquid such that the surface of the wafer is parallel with a surface of the etching liquid; and radiating light from the surface side of the etching liquid onto the surface of the wafer without agitating the etching liquid. First and second etching areas disposed at an interval from each other are defined on the surface of the wafer. In the process of radiating the light onto the surface of the wafer, the light is radiated perpendicularly onto surfaces of the first and second etching areas.

There is provided a structure manufacturing method, including: preparing a wafer at least whose surface comprises Group III nitride crystal in a state of being immersed in an etching solution containing peroxodisulfate ions; and irradiating the surface of the wafer with light through the etching solution; wherein the group III nitride crystal has a composition in which a wavelength corresponding to a band gap is 310 nm or more, and during irradiation of the light, the surface of the wafer is irradiated with a first light having a wavelength of 200 nm or more and less than 310 nm under a first irradiation condition, and is irradiated with a second light having a wavelength of 310 nm or more and less than a wavelength corresponding to the band gap under a second irradiation condition controlled independently of the first irradiation condition.

There is provided a structure manufacturing method, including: preparing an etching target with at least one surface comprising group III nitride; then in a state where the etching target is immersed in an etching solution containing peroxodisulfate ions; irradiating the surface of the etching target with light through the etching solution, and generating sulfate ion radicals from the peroxodisulfate ions and generating holes in the group III nitride, thereby etching the group III nitride, wherein in the etching of the group III nitride, the etching solution remains acidic during a period for etching the group III nitride by making the etching solution acidic at a start of etching the group III nitride, and the etching is performed, with a resist mask formed on the surface.

A structure manufacturing method including: preparing a treatment object that includes an etching target having a surface to be etched comprising a conductive group III nitride and a region to be etched, a conductive member in contact with at least a portion of a surface of a conductive region of the etching target that is electrically connected to the region to be etched, and a mask formed on the surface to be etched and comprising a non-conductive material; and etching the group III nitride by immersing the treatment object in an alkaline or acidic etching solution containing peroxodisulfate ions as an oxidizing agent that accepts electrons, and irradiating the surface to be etched with light through the etching solution, wherein an edge that defines the region to be etched is constituted by an edge of the mask without including an edge of the conductive member.

There is provided a structure manufacturing method, including: preparing a wafer at least whose surface comprises Group III nitride crystal in a state of being immersed in an etching solution containing peroxodisulfate ions; and irradiating the surface of the wafer with light through the etching solution; wherein the group III nitride crystal has a composition in which a wavelength corresponding to a band gap is 310 nm or more, and during irradiation of the light, the surface of the wafer is irradiated with a first light having a wavelength of 200 nm or more and less than 310 nm under a first irradiation condition, and is irradiated with a second light having a wavelength of 310 nm or more and less than a wavelength corresponding to the band gap under a second irradiation condition controlled independently of the first irradiation condition.

A process of preparing a wafer having a diameter of two inches or more, at least a surface of the wafer being formed from a group III nitride crystal, including preparing an alkaline or acidic etching liquid containing a peroxodisulfate ion as an oxidizing agent that accepts an electron, accommodating the wafer such that the surface of the wafer is immersed in the etching liquid such that the surface of the wafer is parallel with a surface of the etching liquid; and radiating light from the surface side of the etching liquid onto the surface of the wafer without agitating the etching liquid. First and second etching areas disposed at an interval from each other are defined on the surface of the wafer. In the process of radiating the light onto the surface of the wafer, the light is radiated perpendicularly onto surfaces of the first and second etching areas.