Semiconductor chip, processed wafer, and method for manufacturing semiconductor chip

A method for manufacturing a semiconductor chip formed with a semiconductor element, the method comprising:

• preparing a gallium nitride wafer made of gallium nitride;
• producing a processed wafer by forming an epitaxial film on a surface of the gallium nitride wafer, the processed wafer having a first surface on a side of the epitaxial film and a second surface on a side of the gallium nitride wafer, the processed wafer including a plurality of chip formation regions adjacent to the first surface of the processed wafer;
• forming a first surface-side element component of the semiconductor element in each of the plurality of chip formation regions;
• forming a wafer transformation layer, in which nitride is separated from gallium, along a planar direction of the processed wafer by irradiating an inside of the processed wafer with a laser beam from the second surface side of the processed wafer;
• dividing the processed wafer at the wafer transformation layer as a boundary into a chip formation wafer including the first surface of the processed wafer and a recycle wafer including the second surface of the processed wafer;
• extracting the semiconductor chip from the chip formation wafer;
• and
• after the preparing of the gallium nitride wafer and before the dividing of the processed wafer, forming a mark inside of one of the gallium nitride wafer and the processed wafer by irradiating an inside of the one with a laser beam, the mark being formed by a deposition of gallium.