Method for forming split starting point in split object, splitting method for split object

摘要

Provided is a method of forming an originating point suitable for splitting a split object by irradiating a laser beam to the split object. With respect to a location for which splitting of the split object M is intended, a laser beam not having strong energy at which a scribe groove can be formed by ablation is irradiated in a state where the focus is defocused -20 mum to -30 mum, from the top surface of the split object M to the inside thereof. An affected region T having an elongated cross-section shape can be formed through rapid heating due to absorption and the following rapid cooling. At the time of break processing, a good break can be realized with the lowermost end portion of the affected region T as the originating point. Further, if once supplied in advance, to an intended split location, a material having a higher absorptance of the laser beam than the split object M in the wavelength range of the used laser beam, the absorption efficiency of the laser beam can be increased only at the location. Therefore, the formation of an affected region functioning as a split originating point can be carried out surely even by an irradiation of a laser beam of weak energy at which no absorption occurs by nature.