A method for manufacturing a wafer from an ingot includes: holding the ingot; applying a laser beam having a wavelength that transmits through the ingot from a front surface of the ingot and positioning a focal point of the laser beam at a position deeper than the front surface of the ingot to form a modified region, and relatively feeding the ingot and the focal point for processing to form a separation layer including a plurality of the modified regions inside the ingot; separating, from the ingot, a workpiece including the front surface of the ingot as the wafer, with the separation layer as a start point; and grinding a separation surface of the wafer to remove the modified region. In the applying, a depth of the focal point forming the modified region is changed to form the separation surface into a three-dimensional shape rather than a horizontal surface.

A method for wafer treatment is disclosed. A wafer is provided with a main surface, a surface layer, and a base layer. The surface layer is disposed between the main surface and the base layer, and the surface layer covers the base layer and exposes the main surface. Then, at least one laser process is performed to fully irradiate the main surface and the surface layer with a first laser to generate a plurality of optimized regions in the main surface and the surface layer, so that the optimized regions form at least one stress-relieving array.