Abstract: A laser oscillation mechanism of a laser beam irradiation unit has a first mode to break growing debris, a second mode to suppress generation of molten debris, and a third mode to break the growing debris and suppress generation of the molten debris. The laser oscillation mechanism includes a selecting part that selects any of the first mode, the second mode, and the third mode. The laser oscillation mechanism sets a repetition frequency with a first group being one unit in the first mode, and sets a repetition frequency with a second group being one unit in the second mode, and sets a repetition frequency with a third group being one unit in the third mode.

Abstract: A laser processing apparatus includes a laser oscillating mechanism for emitting pulsed laser beams. The laser oscillating mechanism includes a group setting section for establishing the number of pulsed laser beams to be applied to a workpiece until a time after which melted debris produced by the pulsed laser beams applied to the workpiece is solidified, and assigns the pulsed laser beams to a group, under conditions that, within a period of time which is shorter than a period of time in which the melted debris is produced, and within a period of time after which a plasma generated by the pulsed laser beam becomes extinct, a next pulsed laser beam is applied to the workpiece to sustain the plasma uninterruptedly to break growing debris, and a time interval setting section for establishing a time interval between the group and another group adjacent thereto.

Abstract: A laser beam irradiating unit of a laser processing apparatus includes a laser oscillating mechanism. The laser oscillating mechanism includes a group setting unit configured to, on a condition that a pulsed laser beam is applied at shorter time intervals than a length of time that molten debris is generated, set the number of pulsed laser beams to be applied until a time that the molten debris is solidified and set the number of pulsed laser beams as one group. A time interval setting unit is configured to set a time until heat generated by application of the pulsed laser beams of the one group is cooled, which serves as a time interval between the one group and an adjacent group, and set time intervals of the pulsed laser beams constituting the one group. The laser oscillating mechanism sets a repetition frequency with the one group as one unit.

Abstract: A laser processing apparatus includes a chuck table that holds a workpiece, a laser beam irradiation unit that irradiates the workpiece with a laser beam, and a feed mechanism that moves the chuck table and the laser beam irradiation unit relative to each other to execute processing feed. The laser beam irradiation unit includes a laser oscillation mechanism that emits a pulsed laser beam and a beam condenser that condenses the pulsed laser beam emitted by the laser oscillation mechanism and irradiates the workpiece with the pulsed laser beam. The laser oscillation mechanism has a group setting part that sets multiple pulsed laser beams into one group and a time interval setting part that sets a time interval of the pulsed laser beams that configure the one group, and sets the repetition frequency in such a manner as to regard the one group as one unit.

Abstract: A laser beam irradiation unit of a laser processing machine includes a laser oscillation unit that emits an initial pulsed laser beam, and a condenser that condenses the initial pulsed laser beam emitted by the laser oscillation unit and focuses a pulsed irradiation laser beam on a wafer having a silicon substrate and held on a chuck table. The laser oscillation unit is configured to oscillate a pulsed laser of deep ultraviolet light at a pulse interval shorter than a thermal diffusion time in an SiO2 film stacked on an upper surface of the silicon substrate, and to emit the initial pulsed laser beam.

Abstract: There is provided a laser processing method for performing laser processing on a wafer having a functional layer on a substrate. The laser processing method includes a blackening step of emitting a pulsed laser beam of a wavelength transparent to the functional layer from a laser oscillator and blackening the functional layer by irradiating the functional layer with the pulsed laser beam of energy equal to or higher than a processing threshold value at which the functional layer is processed such that an overlap ratio of the pulsed laser beam successively applied to the functional layer is equal to or more than 90% and less than 100%, and a groove processing step of forming a laser-processed groove by irradiating the blackened functional layer with the pulsed laser beam and making the blackened functional layer absorb the pulsed laser beam, after performing the blackening step.

Abstract: There is provided a laser processing method for performing laser processing on a wafer having a functional layer on a substrate. The laser processing method includes a blackening step of emitting a pulsed laser beam of a wavelength transparent to the functional layer from a laser oscillator and blackening the functional layer by irradiating the functional layer with the pulsed laser beam of energy equal to or higher than a processing threshold value at which the functional layer is processed such that an overlap ratio of the pulsed laser beam successively applied to the functional layer is equal to or more than 90% and less than 100%, and a groove processing step of forming a laser-processed groove by irradiating the blackened functional layer with the pulsed laser beam and making the blackened functional layer absorb the pulsed laser beam, after performing the blackening step.

Abstract: A laser oscillator of a laser processing apparatus generates burst pulses each composed of a plurality of sub-pulses. The plurality of sub-pulses are generated in such a manner that the energy of the sub-pulse sequentially changes from a lower energy to a higher energy, and the burst pulses are applied to a wafer, whereby the wafer is formed therein with shield tunnels extending from the front surface to the back surface of the wafer and each being composed of a minute hole and an amorphous phase surrounding the minute hole.

Abstract: A laser processing apparatus including a condenser having a function of spherical aberration. Since the condenser has a function of spherical aberration, the focal point of a laser beam to be focused by the condenser and applied to a wafer can be continuously changed in position along the thickness of the wafer. Accordingly, a uniform shield tunnel composed of a fine hole and an amorphous region surrounding the fine hole can be formed so as to extend from the front side of the wafer to the back side thereof, by one shot of the laser beam.

Abstract: A laser processing method for a wafer includes: linearly forming a plurality of shield tunnels each having a fine hole and an amorphous region surrounding the fine hole at predetermined intervals in an inner part of a test substrate, the test substrate having a material and a thickness identical to those of a substrate of the wafer to be processed, while changing time intervals of a plurality of pulses constituting a burst pulse laser beam; and measuring a rupture strength when the test substrate is ruptured along the plurality of shield tunnels. Next, the time intervals of the pulses when the rupture strength is at a minimum are calculated, and a laser processing step is performed which linearly forms a plurality of shield tunnels at predetermined intervals in an inner part of the wafer, by irradiating the wafer with the laser beam having the time intervals of the pulses.

Abstract: Disclosed herein is a laser processing apparatus including a condenser having a function of spherical aberration. Since the condenser has a function of spherical aberration, the focal point of a laser beam to be focused by the condenser and applied to a wafer can be continuously changed in position along the thickness of the wafer. Accordingly, a uniform shield tunnel composed of a fine hole and an amorphous region surrounding the fine hole can be formed so as to extend from, the front side of the wafer to the back side thereof, by one shot of the laser beam.

Abstract: A laser processing apparatus including a condenser having a function of spherical aberration. Since the condenser has a function of spherical aberration, the focal point of a laser beam to be focused by the condenser and applied to a wafer can be continuously changed in position along the thickness of the wafer. Accordingly, a uniform shield tunnel composed of a fine hole and an amorphous region surrounding the fine hole can be formed so as to extend from the front side of the wafer to the back side thereof, by one shot of the laser beam.

Abstract: A method of processing a plate-shaped work-piece with a laser beam so as to be divided along a plurality of projected dicing lines on the workpiece includes: forming a plurality of first shield tunnels, each including fine pores and an amorphous substance surrounding the fine pores, in the workpiece along the projected dicing lines by applying a pulsed laser beam having a wavelength transmittable through the workpiece to the workpiece along the projected dicing lines while positioning a converged zone of the pulsed laser beam within the workpiece; changing the converged zone of the pulsed laser beam to be applied to the workpiece to a position along thicknesswise directions of the workpiece; and, forming a plurality of second shield tunnels in the workpiece adjacent and parallel to the first shield tunnels along the direction in which the pulsed laser bream is applied.

Abstract: A laser processing method for a wafer includes: linearly forming a plurality of shield tunnels each having a fine hole and an amorphous region surrounding the fine hole at predetermined intervals in an inner part of a test substrate, the test substrate having a material and a thickness identical to those of a substrate of the wafer to be processed, while changing time intervals of a plurality of pulses constituting a burst pulse laser beam; and measuring a rupture strength when the test substrate is ruptured along the plurality of shield tunnels. Next, the time intervals of the pulses when the rupture strength is at a minimum are calculated, and a laser processing step is performed which linearly forms a plurality of shield tunnels at predetermined intervals in an inner part of the wafer, by irradiating the wafer with the laser beam having the time intervals of the pulses.

Abstract: A method of processing a wafer includes applying a laser beam having a wavelength that is transmittable through a sapphire substrate to the wafer while positioning a focused spot of the beam within the wafer in regions corresponding to projected dicing lines through a reverse side of the wafer, thereby forming a plurality of shield tunnels made up of a plurality of pores and an amorphous body surrounding the pores, at predetermined spaced intervals in the wafer along the projected dicing lines. A laser beam having a wavelength that is transmittable through the sapphire substrate to the wafer is applied while positioning a focused spot of the laser beam within the wafer in the projected dicing lines through the reverse side of the wafer, thereby forming modified layers between adjacent shield tunnels. Exerting external forces to the wafer divides the wafer into a plurality of optical device chips.

Abstract: A method of processing a wafer includes applying a laser beam having a wavelength that is transmittable through a sapphire substrate to the wafer while positioning a focused spot of the beam within the wafer in regions corresponding to projected dicing lines through a reverse side of the wafer, thereby forming a plurality of shield tunnels made up of a plurality of pores and an amorphous body surrounding the pores, at predetermined spaced intervals in the wafer along the projected dicing lines. A laser beam having a wavelength that is transmittable through the sapphire substrate to the wafer is applied while positioning a focused spot of the laser beam within the wafer in the projected dicing lines through the reverse side of the wafer, thereby forming modified layers between adjacent shield tunnels. Exerting external forces to the wafer divides the wafer into a plurality of optical device chips.

Abstract: An optical device wafer processing method includes a shield tunnel forming step of applying a pulsed laser beam having a transmission wavelength to a sapphire substrate along an area corresponding to each division line from the back side of the sapphire substrate in the condition where the focal point of the pulsed laser beam is set inside the sapphire substrate, thereby forming a plurality of shield tunnels arranged along the area corresponding to each division line, each shield tunnel being composed of a fine hole and an amorphous region formed around the fine hole for shielding the fine hole. The optical device wafer processing method further includes a dividing step of applying an external force to the optical device wafer after performing a light emitting layer forming step, thereby dividing the optical device wafer along the division lines to obtain the individual optical device chips.

Abstract: A laser oscillator of a laser processing apparatus generates burst pulses each composed of a plurality of sub-pulses. The plurality of sub-pulses are generated in such a manner that the energy of the sub-pulse sequentially changes from a lower energy to a higher energy, and the burst pulses are applied to a wafer, whereby the wafer is formed therein with shield tunnels extending from the front surface to the back surface of the wafer and each being composed of a minute hole and an amorphous phase surrounding the minute hole.

Abstract: Disclosed herein is a laser processing apparatus including a condenser having a function of spherical aberration. Since the condenser has a function of spherical aberration, the focal point of a laser beam to be focused by the condenser and applied to a wafer can be continuously changed in position along the thickness of the wafer. Accordingly, a uniform shield tunnel composed of a fine hole and an amorphous region surrounding the fine hole can be formed so as to extend from, the front side of the wafer to the back side thereof, by one shot of the laser beam.

Abstract: Disclosed herein is a laser beam spot shape detection method for detecting a spot shape of a laser beam oscillated by laser beam oscillator and collected by a condenser in a laser machining apparatus, the laser beam spot shape detection method including: a concave mirror holding step of holding a concave mirror having a spherical face forming a reflecting face with a chuck table; a focal point positioning step of positioning the focal point of the condenser in a proximity including the center of the spherical face forming the reflecting face of the concave mirror held by the chuck table; a laser beam irradiation step of irradiating a laser beam onto the held concave mirror, and an imaging step of capturing images of reflected light with a camera.