DIVISION STARTING POIN FORMING METHOD IN BODY TO BE DIVIDED, DIVIDING METHOD FOR BODY TO BE DIVIDED, AND METHOD OF PROCESSING WORK BY PULSE LASER BEAM

摘要

A starting point forming method suitable for dividing a body to be divided by irradiating the body with a laser beam. A location at which the body (M) to be divided is divided is irradiated with a laser beam having energy not strong enough to form a scribe groove due to ablation with its focal point defocused 20-30Vm inward from the upper surface of the body (M) to be divided. A degenerated area (T) having a slender sectional shape is formed by quick heating due to absorption and quick cooling that follows. When the body (M) is broken, a good breaking is accomplished starting at the lower-most end of the degenerated area (T). In addition, when a substance higher in laser beam absorption factor than the body (M) is imparted to a breaking location in advance within the wavelength range of a laser beam to be used, a laser beam absorption efficiency is enhanced at that location only to thereby enable even the irradiation of a laser beam having pulse energy so weak as not to basically cause absorption to positively form a degenerated area serving as a division starting point.