Abstract: An object to be processed can be cut highly accurately along a line to cut. An object to be processed 1 is irradiated with laser light while locating a converging point within a silicon wafer 11, and the converging point is relatively moved along a line to cut 5, so as to form modified regions M1, M2 positioned within the object 1 along the line to cut 5, and then a modified region M3 positioned between the modified regions M1, M2 within the object 1.

Abstract: The present invention relates to a semiconductor chip manufacturing method in which a semiconductor thin film can be cut in a relatively short time and the cut surface can be relatively smoothly formed. When an Si substrate having a diamond thin film formed on the surface thereof is cut in the chip form, a modified region based on multiphoton absorption is formed as a cutting starting point region formed along a cutting planned line by irradiating at least the Si substrate with a laser beam whose condense point is focused to the inside of the Si substrate, along the cutting planned line. The diamond thin film is cut in connection with the cutting of the Si substrate along the cutting starting point region defined by the modified region.

Abstract: A semiconductor substrate cutting method which can efficiently cut a semiconductor substrate having a front face formed with a functional device together with a die bonding resin layer is provided. A wafer 11 having a front face 3 formed with a functional device 15 is irradiated with laser light L while positioning a light-converging point P within the wafer 11 with the rear face 17 of the wafer 11 acting as a laser light incident face, so as to generate multiphoton absorption, thereby forming a starting point region for cutting 8 due to a molten processed region 13 within the wafer 11 along a line along which the substrate should be cut 5. Consequently, a fracture can be generated from the starting point region for cutting 8 naturally or with a relatively small force, so as to reach the front face 3 and rear face 17.

Abstract: Multiphoton absorption is generated, so as to form a part which is intended to be cut 9 due to a molten processed region 13 within a silicon wafer 11, and then an adhesive sheet 20 bonded to the silicon wafer 11 is expanded. This cuts the silicon wafer 11 along the part which is intended to be cut 9 with a high precision into semiconductor chips 25. Here, opposing cut sections 25a, 25a of neighboring semiconductor chips 25, 25 are separated from each other from their close contact state, whereby a die-bonding resin layer 23 is also cut along the part which is intended to be cut 9. Therefore, the silicon wafer 11 and die-bonding resin layer 23 can be cut much more efficiently than in the case where the silicon wafer 11 and die-bonding resin layer 23 are cut with a blade without cutting a base 21.