Abstract: A laser processing method includes: a forming step of forming a plurality of modified spots along an imaginary plane inside a work piece by irradiating an inside of the work piece with laser light from a surface. The work piece includes a first region and second region when viewed in a direction perpendicular to the surface. In the forming step, a plurality of modified spot rows formed of the plurality of modified spots arranged along a boundary between the first region and the second region are formed in the second region, the plurality of modified spot rows being arranged along a direction intersecting an arrangement direction of the plurality of modified spots, and a crack extending from the second region to the first region is formed by forming the plurality of modified spot rows.

Abstract: A semiconductor chip includes: an epitaxial film made of gallium nitride; a semiconductor element disposed in the epitaxial film; a chip formation substrate including the epitaxial film and having a first surface, a second surface opposite to the first surface, and a side surface connecting the first surface and the second surface; and a convex and a concavity on the side surface.

Abstract: A manufacturing method of a semiconductor device, includes: forming a gas vent recess in a first surface of a compound semiconductor substrate, which includes a plurality of device regions adjacent to the first surface, along an interface between the plurality of device regions; forming an altered layer inside the compound semiconductor substrate to extend along the first surface at a depth corresponding to a range of a depth of the gas vent recess by applying a laser beam; dividing the compound semiconductor substrate at the altered layer into a first part including the first surface and a second part including a second surface of the compound semiconductor substrate opposite to the first surface; and forming a metal film to cover a divided surface of the first part while exposing the gas vent recess.

Abstract: A method of manufacturing a gallium nitride substrate includes preparation of a gallium nitride wafer, formation of a transformation layer, and formation of the gallium nitride substrate. The gallium nitride has a first main surface and a second main surface on a side opposite from the first main surface. The gallium nitride wafer is made of a hexagonal crystal, and each of the first main surface and the second main surface is a {1-100} m-plane of the hexagonal crystal. The transformation layer is formed along a planar direction of the gallium nitride wafer by emitting a laser beam into the gallium nitride wafer. The gallium nitride substrate is formed from the gallium nitride wafer by dividing the gallium nitride wafer at the transformation layer. In the formation of the transformation layer, the laser beam is emitted to form an irradiation mark for forming the transformation layer.

Abstract: A method of manufacturing a semiconductor element includes formation of a modified layer, detection of a first region, and cutting of a semiconductor wafer. In the formation of the modified layer, a laser is irradiated on the semiconductor wafer to form the modified layer extending along a surface of the semiconductor wafer inside the semiconductor wafer. The surface of the semiconductor wafer includes a peripheral portion having the first region and a second region. The first region is a region in which the modified layer is not located, and the second region is a region in which the modified layer is formed. In the cutting of the semiconductor wafer, the semiconductor wafer is cut at the modified layer starting from the second region.

Abstract: There is provided a laser processing method for cutting a semiconductor object along a virtual plane facing a surface of the semiconductor object in the semiconductor object. The laser processing method includes a first step of forming a plurality of first modified spots along the virtual plane to obtain first formation density, by causing laser light to enter into the semiconductor object from the surface, and a second step of forming a plurality of second modified spots along the virtual plane so as to obtain second formation density higher than the first formation density, by causing laser light to enter into the semiconductor object from the surface after the first step.

Abstract: A semiconductor chip includes: an epitaxial film made of gallium nitride; a semiconductor element disposed in the epitaxial film; a chip formation substrate including the epitaxial film and having a first surface, a second surface opposite to the first surface, and a side surface connecting the first surface and the second surface; and a convex and a concavity on the side surface.

Abstract: A laser welding apparatus generates laser by a laser oscillator, converges the laser by a condenser lens, and applies the laser to an upper sheet and a lower sheet superposed together so as to weld the upper sheet and the lower sheet to each other. According to this apparatus, by laser irradiation, a melt pool Y is formed in the upper sheet and the lower sheet superposed together. Furthermore, by laser irradiation, the melt pool Y is caused to flow, and the upper sheet and the lower sheet are welded together.

Abstract: A laser welding apparatus generates laser by a laser oscillator, converges the laser by a condenser lens, and applies the laser to an upper sheet and a lower sheet superposed together so as to weld the upper sheet and the lower sheet to each other. According to this apparatus, by laser irradiation, a melt pool Y is formed in the upper sheet and the lower sheet superposed together. Furthermore, by laser irradiation, the melt pool Y is caused to flow, and the upper sheet and the lower sheet are welded together.

Abstract: A laser welding apparatus generates laser by a laser oscillator, converges the laser by a condenser lens, and applies the laser to an upper sheet and a lower sheet superposed together so as to weld the upper sheet and the lower sheet to each other. According to this apparatus, by laser irradiation, a melt pool Y is formed in the upper sheet and the lower sheet superposed together. Furthermore, by laser irradiation, the melt pool Y is caused to flow, and the upper sheet and the lower sheet are welded together.

Abstract: A laser welding apparatus generates laser by a laser oscillator, converges the laser by a condenser lens, and applies the laser to an upper sheet and a lower sheet superposed together so as to weld the upper sheet and the lower sheet to each other. According to this apparatus, by laser irradiation, a melt pool Y is formed in the upper sheet and the lower sheet superposed together. Furthermore, by laser irradiation, the melt pool Y is caused to flow, and the upper sheet and the lower sheet are welded together.