Abstract: A wavelength conversion element is provided as one including a monocrystalline nonlinear optical crystal. The nonlinear optical crystal has: a plurality of first regions having a polarity direction along a predetermined direction; a plurality of second regions having a polarity direction opposite to the predetermined direction; an entrance face into which a fundamental incident wave having a wavelength ? and a frequency ? is incident in a direction substantially perpendicular to the predetermined direction; and an exit face from which a second harmonic with a frequency 2? generated in the crystal emerges. The plurality of first and second regions are formed as alternately arranged in a period substantially equal to d expressed by a predetermined expression, between the entrance face and the exit face.

Abstract: A laser processing method which can accurately cut an object to be processed along a line to cut is provided. A modified region 7 formed by multiphoton absorption forms a cutting start region 8 within an object to be processed 1 along a line 5 along which the object is intended to be cut. Thereafter, the object 1 is irradiated with laser light L2 transmittable through an unmodified region of the object 1, so as to generate fractures 24 from the cutting start region 8 acting as a start point, whereby the object 1 can accurately be cut along the line 5 along which the object is intended to be cut. Expanding an expandable film 19 having the object 1 secured thereto separates individual chips 25 from each other, which can further improve the reliability in cutting the object 1 along the line 5 along which the object is intended to be cut.

Abstract: A laser processing method for preventing particles from occurring from cut sections of chips obtained by cutting a silicon wafer is provided. An irradiation condition of laser light L for forming modified regions 77 to 712 is made different from an irradiation condition of laser light L for forming the modified regions 713 to 719 such as to correct the spherical aberration of laser light L in areas where the depth from the front face 3 of a silicon wafer 11 is 335 ?m to 525 ?m. Therefore, even when the silicon wafer 11 and a functional device layer 16 are cut into semiconductor chips from modified regions 71 to 719 acting as a cutting start point, twist hackles do not appear remarkably in the areas where the depth is 335 ?m to 525 ?m, whereby particles are hard to occur.

Abstract: A laser processing method for preventing particles from occurring from cut sections of chips obtained by cutting a silicon wafer is provided. An irradiation condition of laser light L for forming modified regions 77 to 712 is made different from an irradiation condition of laser light L for forming the modified regions 713 to 719 such as to correct the spherical aberration of laser light L in areas where the depth from the front face 3 of a silicon wafer 11 is 335 ?m to 525 ?m. Therefore, even when the silicon wafer 11 and a functional device layer 16 are cut into semiconductor chips from modified regions 71 to 719 acting as a cutting start point, twist hackles do not appear remarkably in the areas where the depth is 335 ?m to 525 ?m, whereby particles are hard to occur.

Abstract: A method of cutting an object to be processed is provided, which can accurately cut an object to be processed comprising a substrate and a multilayer part provided on the front face of the substrate while having a plurality of functional devices into the functional devices along a line to cut in a short time even when the substrate is thick. A substrate 4 is irradiated with laser light L from the multilayer part 16 side while locating a converging point P within the substrate 4, so as to form a first modified region 71 shifted from the center position CL in the thickness direction of the substrate 4 to the rear face 21 side of the substrate 4 and a second modified region 72 shifted from the center position CL in the thickness direction of the substrate 4 to the front face 3 side of the substrate 4 within the substrate 4 along a line to cut, and generate a fracture 24 from the second modified region 72 to the front face 3 of the substrate 4.

Abstract: An illumination optical system and method illuminates an irradiated surface based on linearly polarized light supplied from a light source. The illumination optical system includes a depolarizer which is selectively positioned between a first position in an optical path of the illumination optical system and a second position outside of the optical path, and has a crystal member whose thickness in a direction along an optical axis of the illumination optical system varies in a direction crossing the optical axis.

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: An illumination optical system illuminates an irradiated surface with light supplied from a light source. The illumination optical system includes a diffractive optical element disposed in an optical path of linearly polarized light supplied from the light source. The diffractive optical element forms a multipole illumination field including a plurality of illumination fields. The illumination optical system also includes an optical integrator that forms a multipole light source including a plurality of planar light sources with light that has passed through the multipole illumination field. The illumination optical system also includes a polarization optical member disposed in an illumination optical path and that sets a polarization direction of light that has passed through the multipole light source to a predetermined polarization direction.

Abstract: A wavelength conversion element is provided as one including a monocrystalline nonlinear optical crystal. The nonlinear optical crystal has: a plurality of first regions having a polarity direction along a predetermined direction; a plurality of second regions having a polarity direction opposite to the predetermined direction; an entrance face into which a fundamental incident wave having a wavelength ? and a frequency ? is incident in a direction substantially perpendicular to the predetermined direction; and an exit face from which a second harmonic with a frequency 2? generated in the crystal emerges. The plurality of first and second regions are formed as alternately arranged in a period substantially equal to d expressed by a predetermined expression, between the entrance face and the exit face.

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: An object to be processed 1 comprising a substrate 4 and a plurality of functional devices 15 formed on a front face 3 of the substrate 4 is irradiated with laser light L while locating a converging point P within the substrate 4, so as to form at least one row of a divided modified region 72, at least one row of a quality modified region 71 positioned between the divided modified region 72 and the front face 3 of the substrate 4, and at least one row of an HC modified region 73 positioned between the divided modified region 72 and a rear face 21 of the substrate 4 for one line to cut 5. Here, in a direction along the line to cut, a forming density of the divided modified region 72 is made lower than that of the quality modified region 71 and that of the HC modified region 73.

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: A laser processing method is provided, which, when cutting a substrate formed with a laminate part including a plurality of functional devices into a plurality of chips, each chip including at least one of the functional devices, can cut the laminate part with a high precision together with the substrate. In this laser processing method, modified regions differing from each other in terms of easiness to cause the substrate 4 to fracture are formed along respective lines to cut 5a to 5d. Therefore, when an expandable tape is attached to the rear face of a substrate 4 and expanded, an object to be processed 1 is cut stepwise into a plurality of chips. Such stepwise cutting allows uniform tensile stresses to act on respective parts extending along the lines to cut 5a to 5d, whereby interlayer insulating films on the lines to cut 5a to 5d are cut with a high precision together with the substrate 4.

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 for preventing particles from occurring from cut sections of chips obtained by cutting a silicon wafer is provided. An irradiation condition of laser light L for forming modified regions 77 to 712 is made different from an irradiation condition of laser light L for forming the modified regions 713 to 719 such as to correct the spherical aberration of laser light L in areas where the depth from the front face 3 of a silicon wafer 11 is 335 ?m to 525 ?m. Therefore, even when the silicon wafer 11 and a functional device layer 16 are cut into semiconductor chips from modified regions 71 to 719 acting as a cutting start point, twist hackles do not appear remarkably in the areas where the depth is 335 ?m to 525 ?m, whereby particles are hard to occur.

Abstract: A method of cutting an object to be processed is provided, which can accurately cut an object to be processed comprising a substrate and a multilayer part provided on the front face of the substrate while having a plurality of functional devices into the functional devices along a line to cut in a short time even when the substrate is thick. A substrate 4 is irradiated with laser light L from the multilayer part 16 side while locating a converging point P within the substrate 4, so as to form a first modified region 71 shifted from the center position CL in the thickness direction of the substrate 4 to the rear face 21 side of the substrate 4 and a second modified region 72 shifted from the center position CL in the thickness direction of the substrate 4 to the front face 3 side of the substrate 4 within the substrate 4 along a line to cut, and generate a fracture 24 from the second modified region 72 to the front face 3 of the substrate 4.

Abstract: An illumination optical system for, when installed in an exposure system, realizing a suitable illumination condition by varying the polarized state of the illumination light according to the pattern characteristics of the mask while suppressing the loss of the intensity of the light. The illumination optical system has a light source unit for supplying a linearly polarized light for illuminating surfaces to be illuminated therewith, and a polarized state changing device for changing the polarized state of the illuminating light from a predetermined polarized state to a nonpolarized state and vice versa. The polarized state changing device is arranged in the optical path between the light source unit and the surfaces to be illuminated. The polarized state changing device can be removed from the illumination optical path and has a depolarizer for selectively depolarizing the incident linearly polarized light.