Abstract: A wafer having a front face formed with a functional device is irradiated with laser light while positioning a light-converging point within the wafer with the rear face of the wafer acting as a laser light incident face, so as to generate multiphoton absorption, thereby forming a starting point region for cutting due to a molten processed region within the wafer along a line. Consequently, a fracture can be generated from the starting point region for cutting naturally or with a relatively small force, so as to reach the front face and rear face. Therefore, when an expansion film is attached to the rear face of the wafer by way of a die bonding resin layer after forming the starting point region for cutting and then expanded, the wafer and die bonding resin layer can be cut along the line.

Abstract: A method of cutting an object to be processed comprises the steps of irradiating an object to be processed with a laser light which is an elliptically-polarized light having an ellipticity other than 1 such that a direction of polarization of the laser light intersects a line to cut the object and a thickness direction of the object, while locating a converging point of the laser light within the object, so as to form a modified region within the object along the line and generate a fracture from the modified region in the thickness direction of the object, and causing the fracture to reach front and rear faces of the object so as to cut the object along the line.

Abstract: A method of cutting an object to be processed comprises the steps of irradiating an object to be processed with a laser light which is an elliptically-polarized light having an ellipticity other than 1 such that a direction of polarization of the laser light intersects a line to cut the object and a thickness direction of the object, while locating a converging point of the laser light within the object, so as to form a modified region within the object along the line and generate a fracture from the modified region in the thickness direction of the object, and causing the fracture to reach front and rear faces of the object so as to cut the object along the line.

Abstract: A method for cutting a semiconductor substrate having a front face formed with functional devices together with a die bonding resin layer. A wafer having a front face formed with functional devices is irradiated with laser light while positioning a light-converging point within the wafer with the rear face of the wafer acting as a laser light incident face, so as to form a starting point region for cutting due to a modified region within the wafer along a cutting line. When an expansion film is attached to the rear face by way of a die bonding resin layer after forming the starting point region and then expanded, a fracture can be generated from the starting point region which reaches the front face and rear face, consequently, the wafer and die bonding resin layer can be cut along the cutting line.

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: A laser beam machining method and a laser beam machining device capable of cutting a work without producing a fusing and a cracking out of a predetermined cutting line on the surface of the work, wherein a pulse laser beam is radiated on the predetermined cut line on the surface of the work under the conditions causing a multiple photon absorption and with a condensed point aligned to the inside of the work, and a modified area is formed inside the work along the predetermined determined cut line by moving the condensed point along the predetermined cut line, whereby the work can be cut with a rather small force by cracking the work along the predetermined cut line starting from the modified area and, because the pulse laser beam radiated is not almost absorbed onto the surface of the work, the surface is not fused even if the modified area is formed.

Abstract: A laser beam machining method and a laser beam machining device capable of cutting a work without producing a fusing and a cracking out of a predetermined cutting line on the surface of the work, wherein a pulse laser beam is radiated on the predetermined cut line on the surface of the work under the conditions causing a multiple photon absorption and with a condensed point aligned to the inside of the work, and a modified area is formed inside the work along the predetermined determined cut line by moving the condensed point along the predetermined cut line, whereby the work can be cut with a rather small force by cracking the work along the predetermined cut line starting from the modified area and, because the pulse laser beam radiated is not almost absorbed onto the surface of the work, the surface is not fused even if the modified area is formed.

Abstract: While a converging lens 108 is relatively moved along a line 50 including a line to cut 5, measuring laser light L2 is converged with the lens 108 when the lens 108 is positioned on a processing region 30 having an outer shape between an object to be processed 1 and a frame 22, and a reflected light component of the laser light L2 reflected by a front face 3 of the object 1 is detected. While keeping a substantially constant distance between the front face 3 and the lens 108 such that a converging point P of processing laser light L1 is positioned at a constant distance from the front face 3 according to the detection, the laser light L1 is converged by the lens 108, so as to form a molten processed region 13 within the object 1.

Abstract: A modified region is accurately formed at a desirable position with respect to a laser light irradiation surface of an object to be processed. When an average difference ? has a value exceeding a predetermined threshold during trace recording, a particle segment Z including a line segment S where the average difference ? exceeds the predetermined threshold is defined. This determines that a particle exists on a line to cut 5 and randomly reflects measuring laser light, whereby a segment where the presence of the particle affects a control signal in a line segment to cut is detected as the particle segment Z. Correcting the control signal in the particle segment Z inhibits a converging lens from moving more than necessary because of an error included in the signal value under the influence of the presence of the particle, thus allowing the converging point of the processing laser light to accurately follow a front face 3.

Abstract: A converging point of processing laser light is made to accurately follow a laser light irradiation surface of an object to be processed. An object to be processed 1 is irradiated with measuring laser light along a line to cut 5, astigmatism is added to a reflected light component of the measuring laser light reflected by a front face 3 of the object 1 irradiated with the measuring laser light, a displacement sensor signal corresponding to a converged light image of the reflected light component having the astigmatism added thereto is detected, and the displacement sensor signal is made to become a feedback reference value corresponding to the quantity of the reflected light component, so as to locate the converging point of the processing laser light at a predetermined position with respect to the front face 3.

Abstract: A laser beam machining method and a laser beam machining device capable of cutting a work without producing a fusing and a cracking out of a predetermined cutting line on the surface of the work, wherein a pulse laser beam is radiated on the predetermined cut line on the surface of the work under the conditions causing a multiple photon absorption and with a condensed point aligned to the inside of the work, and a modified area is formed inside the work along the predetermined determined cut line by moving the condensed point along the predetermined cut line, whereby the work can be cut with a rather small force by cracking the work along the predetermined cut line starting from the modified area and, because the pulse laser beam radiated is not almost absorbed onto the surface of the work, the surface is not fused even if the modified area is formed.

Abstract: A laser beam machining method and a laser beam machining device capable of cutting a work without producing a fusing and a cracking out of a predetermined cutting line on the surface of the work, wherein a pulse laser beam is radiated on the predetermined cut line on the surface of the work under the conditions causing a multiple photon absorption and with a condensed point aligned to the inside of the work, and a modified area is formed inside the work along the predetermined determined cut line by moving the condensed point along the predetermined cut line, whereby the work can be cut with a rather small force by cracking the work along the predetermined cut line starting from the modified area and, because the pulse laser beam radiated is not almost absorbed onto the surface of the work, the surface is not fused even if the modified area is formed.

Abstract: In the laser processing method, the cross-sectional form of laser light L at a converging point P is such that the maximum length in a direction perpendicular to a line to cut 5 is shorter than the maximum length in a direction parallel to the line to cut 5. Therefore, when seen from the incident direction of the laser light L, a modified region 7 formed within a silicon wafer 11 has such a shape that the maximum length in the direction perpendicular to the line to cut 5 is shorter than the maximum length in the direction parallel to the line to cut 5. Forming the modified region 7 having such a shape within the object 1 can restrain twist hackles from occurring on cut surfaces when cutting the object 1 from the modified region 7 acting as a cutting start point, thereby making it possible to improve the flatness of the cut surfaces.

Abstract: An object to be processed 1 is irradiated with laser light L with a standard pulse waveform, so as to form a molten processed region 131, which has a larger size in the thickness direction of the object 1 and is easy to generate a fracture 24 in the thickness direction of the object 1, within a silicon wafer 111, and with laser light L with a retarded pulse waveform, so as to form a molten processed region 132, which has a smaller size in the thickness direction of the object 1 and is hard to generate the fracture 24 in the thickness direction of the object 1, within a silicon wafer 112.

Abstract: A laser beam machining method and a laser beam machining device capable of cutting a work without producing a fusing and a cracking out of a predetermined cutting line on the surface of the work, wherein a pulse laser beam is radiated on the predetermined cut line on the surface of the work under the conditions causing a multiple photon absorption and with a condensed point aligned to the inside of the work, and a modified area is formed inside the work along the predetermined determined cut line by moving the condensed point along the predetermined cut line, whereby the work can be cut with a rather small force by cracking the work along the predetermined cut line starting from the modified area and, because the pulse laser beam radiated is not almost absorbed onto the surface of the work, the surface is not fused even if the modified area is formed.

Abstract: A laser processing apparatus comprises a converging lens 31 for converging processing laser light and rangefinding laser light L2 toward a wafer 1, an actuator for actuating the lens 31, a shaping optical system 49 for adding astigmatism to reflected light L3 of the rangefinding laser light, a quadrant photodiode 42 for receiving the reflected light L3 and outputting voltage values corresponding to its light quantities, and a controller for regulating the actuator, and positions a converging point P2 of the rangefinding laser light L2 between a focal point P0 of the lens and the lens 31, so as to make it possible to form a modified region at a position deeper from the front face 3, thereby suppressing adverse effects due to the reflected light L3. The control is based on an arithmetic value subjected to a division by a sum of the voltage values, so as to prevent the arithmetic value from being changed by the quantity of reflected light.

Abstract: A laser beam machining method and a laser beam machining device capable of cutting a work without producing a fusing and a cracking out of a predetermined cutting line on the surface of the work, wherein a pulse laser beam is radiated on the predetermined cut line on the surface of the work under the conditions causing a multiple photon absorption and with a condensed point aligned to the inside of the work, and a modified area is formed inside the work along the predetermined determined cut line by moving the condensed point along the predetermined cut line, whereby the work can be cut with a rather small force by cracking the work along the predetermined cut line starting from the modified area and, because the pulse laser beam radiated is not almost absorbed onto the surface of the work, the surface is not fused even if the modified area is formed.

Abstract: A laser processing method which can efficiently perform laser processing while minimizing the deviation of the converging point of a laser beam in end parts of an object to be processed is provided. This laser processing method comprises a displacement acquiring step (S06 and S07) of acquiring a displacement between a point on the line to cut and one end of the line to cut in the object while irradiating the object with a second laser beam, converged by a lens, for measuring the displacement of a main surface of the object; and a position setting step (S08 and S09) of setting an initial position for holding the lens with respect to the main surface of the object according to the acquired displacement, and holding the lens at thus set initial position.

Abstract: A laser processing method which can efficiently perform laser processing while minimizing the deviation of the converging point of a laser beam in end parts of an object to be processed is provided.

Abstract: A laser processing method which can efficiently perform laser processing while minimizing the deviation of the converging point of a laser beam is provided. This laser processing method comprises a displacement acquiring step (S07 to S11) of irradiating an object to be processed with a rangefinding laser beam for measuring a displacement of a main surface of the object while converging the laser beam with a lens and acquiring the displacement of the main surface along a line to cut while detecting reflected light reflected by the main surface in response to the irradiation; and moves the processing objective lens and the object relative to each other along the main surface, while adjusting the gap between the processing objective lens and the surface according to the displacement acquired by the displacement acquiring step, thereby forming the modified region along the line to cut.