β Gallium oxide substrate manufacturing method

A β gallium oxide substrate manufacturing method for manufacturing a substrate from a workpiece formed of β gallium oxide, wherein the workpiece is manufactured in such a manner that a crystal plane {001} of the β gallium oxide is exposed on a front surface of the workpiece, comprising:

• a separation layer forming step of applying a laser beam of such a wavelength as to be transmitted through the β gallium oxide to the workpiece, in a state in which a focal point where the laser beam is concentrated is positioned at a predetermined depth from the front surface of the workpiece, to form a separation layer including a modified part and a crack extending from the modified part, inside the workpiece;
• and
• a separation step of exerting an external force on the workpiece to thereby separate the substrate from the workpiece, with the separation layer as a start point, after the separation layer forming step;
• in the separation layer forming step, application of the laser beam to the workpiece while the workpiece and the focal point are moved relative to each other in the predetermined direction forming an angle of not more than 35° relative to a straight line parallel to a crystal orientation [100] of the β gallium oxide and relative movement, in a direction orthogonal to the predetermined direction, of the workpiece and a position where the focal point is formed are alternately repeated.