KR20230139769A - Laser processing apparatus and laser processing method - Google Patents

Abstract

The laser processing device forms a modified region inside the object by irradiating laser light to the object on which a light-transmitting member is provided on the laser light incident surface. The laser processing device includes a support unit, an irradiation unit, a triangulation sensor, a moving mechanism, a storage unit, a determination unit, and a positioning unit. The determination unit determines one of the plurality of light reception position information stored in the storage unit as the reference light reception position information. The positioning unit operates the moving mechanism to move at least one of the irradiation unit and the support unit so that the light receiving position of the light receiving element array of the triangular rangefinding sensor becomes the light receiving position corresponding to the reference light receiving position information, and moves at least one of the irradiation part and the support part to create a condensing lens with respect to the laser light incident surface. The position in the optical axis direction is adjusted to a predetermined height position.

Description

Laser processing device and laser processing method {LASER PROCESSING APPARATUS AND LASER PROCESSING METHOD}

The present disclosure relates to a laser processing device and a laser processing method.

A laser processing device that forms a modified region by irradiating laser light to an object is known (for example, see Japanese Patent Application Laid-Open No. 2008-87053). Such a laser processing device includes a support part that supports an object, an irradiation part that irradiates laser light to the object through a condensing lens, and a moving mechanism that moves the irradiation part along the optical axis direction of the condensing lens.

The laser processing device described above projects a reticle onto the laser incident surface of an object, captures an image of the laser light incident surface with an imaging unit, and operates a moving mechanism so that the reticle is focused on the image, thereby making laser light incident. There are cases where alignment (so-called height setting) is performed to align the position of the condenser lens in the optical axis direction with respect to the surface to a predetermined height position. However, for example, when a wafer on which a transparent member such as a transparent tape is provided on the laser beam incident surface is used as the object, the reticle becomes blurred on the image, the reticle cannot be correctly identified, and the positioning of the condenser lens is difficult. There is a risk of getting into trouble. In particular, if the thickness of the transparent member is large, this concern becomes significant.

Therefore, the present disclosure provides a laser processing device and a laser capable of reliably aligning the position of the condensing lens in the optical axis direction with respect to the laser beam incident surface, even in an object in which a light-transmitting member is provided on the laser beam incident surface. The purpose is to provide a processing method.

A laser processing device according to one aspect of the present disclosure is a laser processing device in which a transmission member having light transparency irradiates laser light to an object provided on a laser light incident surface to form a modified region in the object, and supports the object. A triangulation sensor having a support portion, an irradiation portion that irradiates laser light to an object through a condensing lens, and a light receiving element array provided in the irradiation portion that receives the laser light for measurement reflected from the laser beam incidence surface, and the optical axis direction of the condensing lens. Accordingly, a moving mechanism that moves at least one of the irradiation unit and the support unit, a storage unit that stores a plurality of light-receiving position information regarding the light-receiving position of the light-receiving element array, and one of the plurality of light-receiving position information stored in the storage unit, The moving mechanism is operated to move at least one of the irradiation section and the support section so that the light-receiving position of the determining portion and the light-receiving element array that determines the reference light-receiving position information becomes the light-receiving position corresponding to the reference light-receiving position information, so that at least one of the irradiation portion and the support portion is moved to the laser beam incident surface. A position adjusting unit is provided to adjust the position of the condenser lens in the optical axis direction to a predetermined height position.

The laser processing method according to one aspect of the present disclosure is a laser processing method using a laser processing device in which a light-transmitting member irradiates laser light to an object provided on the laser light incident surface to form a modified region in the object. , the laser processing device has a support part for supporting an object, an irradiation part for irradiating laser light to the object through a condenser lens, and a light receiving element array provided in the irradiation part to receive the laser light for measurement reflected from the laser light incident surface. A first step comprising a triangular range sensor and a movement mechanism for moving at least one of the irradiation unit and the support unit along the optical axis direction of the condenser lens, and storing a plurality of light-receiving position information regarding the light-receiving position of the light-receiving element array; A second step of determining one of the plurality of light-receiving position information as the reference light-receiving position information, and operating the moving mechanism so that the light-receiving position of the light-receiving element array becomes a light-receiving position corresponding to the reference light-receiving position information, It includes a third step of moving at least one side to adjust the position of the condensing lens in the optical axis direction with respect to the laser beam incident surface to a predetermined height position.

The present inventors have conducted extensive studies and found that, in the triangulation method using laser light for measurement, there is a transmission member between the light receiving position of the light receiving element array and the position in the optical axis direction of the condenser lens with respect to the laser light incident surface. Even in the case where is provided on the laser beam incident surface, it was found that there is a certain correlation. Therefore, in one aspect of the present disclosure, a plurality of light-receiving position information is stored, and which of these is relevant when setting the height is selected as a reference light-receiving position based on, for example, an input from the user, an internal observation result, or a cut surface observation result. Make decisions based on information. Then, by operating the movement mechanism to become the light receiving position of the determined reference light receiving position information, it becomes possible to reliably perform height setting regardless of the observation of the laser beam incident surface by the imaging unit. That is, even for an object in which a light-transmitting member is provided on the laser light incident surface, it is possible to reliably align the position of the condenser lens in the optical axis direction with respect to the laser light incident surface.

In the laser processing device according to one aspect of the present disclosure, the determination unit may determine light-receiving position information when the depth position of the modified region formed by irradiating the laser light by the irradiation unit corresponds to the target depth position as reference light-receiving position information. . In the laser processing method according to one aspect of the present disclosure, in the first step, at least one of the irradiation unit and the support unit is moved by a moving mechanism, and then the laser light is irradiated by the irradiation unit to form a modified area on the object. The step of acquiring the light-receiving position information by receiving the laser light for measurement reflected from the incident surface by the light-receiving element array is repeated multiple times by changing the movement amount of the moving mechanism, and in the second step, the modified region formed in the first step is Light-receiving position information when the depth position corresponds to the target depth position may be determined as reference light-receiving position information.

When the depth position of the modified region formed in the object corresponds to the target depth position, it is found that height setting is appropriately performed during laser processing. Accordingly, in one aspect of the present disclosure, it is possible to determine light-receiving position information when the depth position of the modified region formed in the object corresponds to the target depth position as reference light-receiving position information related to height setting.

In the laser processing device according to one aspect of the present disclosure, the storage unit may store reference light-receiving position information in association with each of a plurality of objects. In the laser processing method according to one aspect of the present disclosure, in the second step, reference light reception position information may be stored in association with each of a plurality of objects. In this case, it becomes possible to automatically set height for each object.

In the laser processing device according to one aspect of the present disclosure, the storage unit may store reference light-receiving position information in association with each row of a plurality of modified regions formed in one object. In the second step of the laser processing method according to one aspect of the present disclosure, reference light-receiving position information may be stored in association with each row of a plurality of modified regions formed in one object. In this case, it becomes possible to automatically set the height for each row (so-called processing pass) of a plurality of modified regions formed in one object.

In the laser processing device according to one aspect of the present disclosure, the light-receiving position of the light-receiving element array may be a position obtained by performing a centroid calculation on the amount of light received in the area where the laser light for measurement is incident on the light-receiving element array. In the laser processing method according to one aspect of the present disclosure, the light-receiving position of the light-receiving element array may be a position obtained by performing a centroid calculation on the amount of light received in the area where the laser light for measurement is incident on the light-receiving element array. The measurement laser light incident on the light-receiving element array may have diffusivity due to spherical aberration of the transmission member. According to one aspect of the present disclosure, even if the laser light for measurement has diffusion properties, it is possible to obtain the light-receiving position of the light-receiving element array with high precision using centroid calculation.

1 is a perspective view showing a laser processing device according to an embodiment.
Figure 2 is a perspective view of an object mounted on a support of a laser processing device according to an embodiment.
Figure 3 is a cross-sectional view along the XY plane of Figure 1.
Figure 4 is a perspective view showing a part of the laser output unit and the laser concentrator of the laser processing device according to the embodiment.
Figure 5 is a cross-sectional view along the XY plane of Figure 1.
FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 5.
FIG. 7 is a cross-sectional view taken along line VII-VII of FIG. 6.
Fig. 8 is a front view showing the schematic configuration of a separate axis ranging sensor according to the embodiment.
FIG. 9 is a diagram showing a state in which a reticle mark is in focus in an image of a laser light incident surface captured by an observation camera according to an embodiment.
Fig. 10 is a flowchart showing an example of acquiring initial spot position information.
Figure 11 is a flow chart showing an example of a height set.
Figure 12 is a cross-sectional view of the object showing the formation of a modified region in the modified region formation mode.
Figure 13 is a cross-sectional view of the object showing the formation of a modified region in the modified region formation mode.
Figure 14(a) is a cross-sectional view showing an object on which a modified region is formed by the modified region formation mode. Figure 14(b) is a cross-sectional view showing an object on which a modified region is formed by the modified region formation mode. Figure 14(c) is a cross-sectional view showing an object on which a modified region is formed by the modified region formation mode. Figure 14(d) is a cross-sectional view showing an object on which a modified region is formed by the modified region formation mode. Figure 14(e) is a cross-sectional view showing an object on which a modified region is formed by the modified region formation mode. Figure 14(f) is a cross-sectional view showing an object on which a modified region is formed by the modified region formation mode. Figure 14(g) is a cross-sectional view showing an object on which a modified region is formed by the modified region formation mode. Figure 14(h) is a cross-sectional view showing an object on which a modified region is formed by the modified region formation mode.
Figure 15(a) is a front view of a linear photodiode array for explaining calculation of spot positions. FIG. 15(b) is an enlarged view of a portion of FIG. 15(a).

Hereinafter, embodiments will be described in detail with reference to the drawings. In each drawing, identical or equivalent parts are assigned the same reference numerals, and overlapping descriptions are omitted. The directions perpendicular to each other in the horizontal plane are referred to as the X-axis direction and the Y-axis direction, and the vertical direction is referred to as the Z-axis direction.

As shown in FIG. 1, in the laser processing apparatus 200, a modified region is formed in the object 1 by irradiating laser light to the object 1. As the object 1, a plate-shaped member (for example, a substrate, a wafer, etc.) containing a semiconductor substrate made of a semiconductor material or a piezoelectric substrate made of a piezoelectric material is used. As shown in FIG. 2, a cutting line 5 for cutting the object 1 is set on the object 1. The cutting line 5 is an imaginary line extending in a straight line. When forming a modified area inside the object 1, the laser light is relatively moved along the cutting line 5 with the light converging point (at least a part of the concentrating area) aligned with the inside of the object 1. . Thereby, a modified area is formed in the object 1 along the cutting line 5.

The line to be cut 5 is not limited to a straight line, but may have a curved shape, a three-dimensional shape that is a combination of these, or may have designated coordinates. The cutting line 5 is not limited to an imaginary line, and may be a line actually drawn on the surface of the object 1. The modified region may be formed continuously or intermittently. The modified region may be in the form of rows or dots, and the point is that the modified region should be formed at least inside the object 1. Additionally, cracks may be formed starting from the modified area, and the crack and modified area may be exposed to the outer surface (front, back, or outer peripheral surface) of the object 1. The laser light incident surface when forming the modified region is not limited to the surface of the object 1, and may be the back surface of the object 1.

The modified area refers to an area in which density, refractive index, mechanical strength or other physical properties are different from those of the surrounding area. Examples of the reformed region include a melt processing region (meaning at least one of a region once melted and then resolidified, a region in a molten state, and a region in a state resolidified from melting), a crack region, and insulation. There are destruction areas, refractive index change areas, etc., and there are also areas where these are mixed. The modified region includes a region where the density of the modified region has changed compared to the density of the unmodified region in the material of the object 1, or a region where lattice defects have been formed. When the material of the object 1 is single crystal silicon, the modified region can also be called a high dislocation density region.

The melt-processed region, the refractive index change region, the region where the density of the modified region has changed compared to the density of the unmodified region, and the region where lattice defects have been formed are the interior of these regions or the interface between the modified region and the unmodified region. There are cases where there are cracks (chips, micro cracks) in the product. The contained cracks may extend over the entire modified area, or may be formed only in part or in multiple areas. The object 1 includes a substrate made of a crystalline material with a crystalline structure. For example, the object 1 includes a substrate formed of at least one of gallium nitride (GaN), silicon (Si), silicon carbide (SiC), LiTaO ₃ , and sapphire (Al ₂ O ₃ ). In other words, the object 1 includes, for example, a gallium nitride substrate, a silicon substrate, a SiC substrate, a LiTaO ₃ substrate, or a sapphire substrate. The crystal material may be either an anisotropic crystal or an isotropic crystal. Additionally, the object 1 may include a substrate made of an amorphous material having an amorphous structure (amorphous structure), for example, a glass substrate.

In the embodiment, a modified region can be formed by forming a plurality of modified spots (processing marks) along the cutting line 5. In this case, a plurality of modified spots gather to form a modified area. A modified spot is a modified portion formed by one pulse of pulsed laser light (i.e., one pulse of laser irradiation: laser shot). Modification spots include crack spots, melt processing spots, refractive index change spots, or a mixture of at least one of these. Regarding the modified spot, its size and the length of the crack that occurs can be appropriately controlled by considering the required cutting precision, required flatness of the cut surface, thickness, type, crystal orientation, etc. of the object 1. In the embodiment, a modified spot can be formed as a modified area along the cutting line 5.

As shown in FIG. 1, the laser processing device 200 includes an apparatus frame 210, a first moving mechanism 220, a support (support portion) 230, and a second moving mechanism (moving mechanism) 240. ) is provided. Additionally, the laser processing device 200 includes a laser output unit 300, a laser concentrator (irradiation unit) 400, and a control unit 500.

The first moving mechanism 220 is mounted on the device frame 210. The first moving mechanism 220 has a first rail unit 221, a second rail unit 222, and a movable base 223. The first rail unit 221 is mounted on the device frame 210. The first rail unit 221 is provided with a pair of rails 221a and 221b extending along the Y-axis direction. The second rail unit 222 is mounted on a pair of rails 221a and 221b of the first rail unit 221 so as to be movable along the Y-axis direction. The second rail unit 222 is provided with a pair of rails 222a and 222b extending along the X-axis direction. The movable base 223 is mounted on a pair of rails 222a and 222b of the second rail unit 222 so as to be movable along the X-axis direction. The movable base 223 is rotatable with the axis parallel to the Z-axis direction as its center line.

The support 230 is mounted on the movable base 223. The support 230 supports the object 1. In the example shown in FIG. 2, the object 1 is, for example, a plurality of functional elements (a light-receiving element such as a photodiode, a light-emitting element such as a laser diode, or Circuit elements formed as a circuit, etc.) are formed in a matrix shape. When the object 1 is supported on the support 230, for example, the surface 1a (the surface on the side of the plurality of functional elements) of the object 1 is placed on the film 12 spread on the annular frame 11. ) is attached. The support stand 230 supports the object 1 by holding the frame 11 with a clamp and adsorbing the film 12 with a vacuum chuck table. On the support stand 230, the object 1 is provided with a plurality of mutually parallel cutting lines 5a and a plurality of mutually parallel cutting lines 5b between adjacent functional elements (hereinafter, It is set up in a grid shape to pass through (also called “street”).

As shown in FIG. 1, the support stand 230 is moved along the Y-axis direction when the second rail unit 222 operates in the first moving mechanism 220. Additionally, the support stand 230 is moved along the X-axis direction when the movable base 223 operates in the first moving mechanism 220. Additionally, the support stand 230 is rotated with the axis parallel to the Z-axis direction as the center line when the movable base 223 operates in the first moving mechanism 220. In this way, the support 230 is mounted on the device frame 210 so that it can move along the X-axis direction and the Y-axis direction and can rotate around the axis parallel to the Z-axis direction as the center line.

The laser output unit 300 is mounted on the device frame 210. The laser concentrator 400 is mounted on the device frame 210 via the second moving mechanism 240. The laser concentrator 400 is moved along the Z-axis direction (optical axis direction of the condenser lens unit 430 to be described later) by operating the second moving mechanism 240. In this way, the laser concentrator 400 is mounted on the device frame 210 so that it can move along the Z-axis direction with respect to the laser output unit 300.

The control unit 500 is composed of a Central Processing Unit (CPU), Read Only Memory (ROM), and Random Access Memory (RAM). The control unit 500 controls the operation of each part of the laser processing device 200. Details of processing by the control unit 500 will be described later.

In the laser processing apparatus 200, a modified region is formed inside the object 1 along each of the intended cutting lines 5a and 5b, for example, as follows. First, the object 1 is supported on the support 230 so that the back surface 1b of the object 1 becomes the laser light incident surface, and each cutting line 5a of the object 1 is parallel to the X-axis direction. It is aligned in one direction. Alignment (so-called height set) is performed to align the position of the condensing lens unit 430, which will be described later, in the Z-axis direction with respect to the laser beam incident surface to the reference position. The laser concentrator 400 is moved in the Z-axis direction by the second moving mechanism 240 so that the converging point of the laser light L is located at a position separated by a predetermined distance from the laser beam incident surface inside the object 1. is moved to While the distance between the laser light incident surface and the converging point of the laser light L is maintained constant, the condensing point of the laser light L is relatively moved along each cutting line 5a. As a result, a modified region is formed inside the object 1 along each cutting line 5a. The laser light incident surface is not limited to the back surface 1b, and may be the surface 1a.

When the formation of the modified area along each scheduled cutting line 5a is completed, the support 230 is rotated by the first moving mechanism 220, and each scheduled cutting line 5b of the object 1 is moved along the X-axis. It is aligned in a direction parallel to the direction. A height set is performed. The laser concentrator 400 is moved by the second moving mechanism 240 so that the converging point of the laser light L is located at a position separated by a predetermined distance from the laser beam incident surface inside the object 1. While the distance between the laser light incident surface and the converging point of the laser light L is maintained constant, the condensing point of the laser light L is relatively moved along each cutting line 5b. As a result, a modified region is formed inside the object 1 along each cutting line 5b.

In this way, in the laser processing apparatus 200, the direction parallel to the X-axis direction is the processing direction (scanning direction of the laser light L). In addition, the relative movement of the converging point of the laser light L along each scheduled cutting line 5a and the relative movement of the converging point of the laser light L along each scheduled cutting line 5b are determined by the first moving mechanism. This is carried out by moving the support 230 along the X-axis direction at 220. In addition, the relative movement of the converging point of the laser light L between each scheduled cutting line 5a and the relative movement of the converging point of the laser light L between each scheduled cutting line 5b are the first This is carried out by moving the support stand 230 along the Y-axis direction by the moving mechanism 220.

As shown in FIG. 3, the laser output unit 300 has a mounting base 301, a cover 302, and a plurality of mirrors 303 and 304. In addition, the laser output unit 300 includes a laser oscillator (laser light source) 310, a shutter 320, a λ/2 wave plate unit (output adjustment unit, polarization direction adjustment unit) 330, and a polarizer unit (output adjustment unit). , a polarization direction adjustment unit) 340, a beam expander (laser beam collimating unit) 350, and a mirror unit 360.

The mounting base 301 includes a plurality of mirrors 303 and 304, a laser oscillator 310, a shutter 320, a λ/2 wave plate unit 330, a polarizer unit 340, a beam expander 350, and a mirror unit. (360) is supported. A plurality of mirrors 303, 304, a laser oscillator 310, a shutter 320, a λ/2 wave plate unit 330, a polarizer unit 340, a beam expander 350, and a mirror unit 360 are mounted. It is mounted on the main surface 301a of the base 301. The mounting base 301 is a plate-shaped member and is removable from the device frame 210 (see FIG. 1). The laser output unit 300 is mounted on the device frame 210 via a mounting base 301. That is, the laser output unit 300 is detachable from the device frame 210.

The cover 302 is on the main surface 301a of the mounting base 301 and includes a plurality of mirrors 303 and 304, a laser oscillator 310, a shutter 320, a λ/2 wave plate unit 330, It covers the polarizer unit 340, beam expander 350, and mirror unit 360. The cover 302 is removable from the mounting base 301.

The laser oscillator 310 pulses linearly polarized laser light (L) along the X-axis direction. The wavelength of the laser light L emitted from the laser oscillator 310 is included in any of the wavelength bands of 500-550 nm, 1000-1150 nm, or 1300-1400 nm. Laser light (L) in the wavelength range of 500 to 550 nm is suitable for internal absorption type laser processing of a substrate made of, for example, sapphire. Laser light (L) in each wavelength range of 1000 to 1150 nm and 1300 to 1400 nm is suitable for internal absorption type laser processing for, for example, a substrate made of silicon. The polarization direction of the laser light L emitted from the laser oscillator 310 is, for example, a direction parallel to the Y-axis direction. The laser light L emitted from the laser oscillator 310 is reflected by the mirror 303 and enters the shutter 320 along the Y-axis direction.

In the laser oscillator 310, the output of the laser light L is switched ON/OFF as follows. When the laser oscillator 310 is composed of a solid-state laser, the ON/OFF of the Q switch (AOM (acousto-optic modulator), EOM (electro-optic modulator), etc.) provided in the resonator is switched ON/OFF, thereby outputting the laser light (L). is switched ON/OFF at high speed. When the laser oscillator 310 is composed of a fiber laser, the output of the semiconductor laser constituting the seed laser and the amplifier (excitation) laser is switched ON/OFF, thereby turning the output of the laser light (L) ON/OFF. Converts at high speed. When the laser oscillator 310 uses an external modulation element, the output of the laser light (L) is switched ON/OFF at high speed by switching ON/OFF of the external modulation element (AOM, EOM, etc.) provided outside the resonator. do.

The shutter 320 opens and closes the optical path of the laser light L using a mechanical mechanism. As described above, the ON/OFF switching of the output of the laser light L from the laser output unit 300 is performed by switching the ON/OFF switching of the output of the laser light L from the laser oscillator 310. However, by providing the shutter 320, for example, sudden emission of the laser light L from the laser output unit 300 is prevented. The laser light L that has passed through the shutter 320 is reflected by the mirror 304 and sequentially enters the λ/2 wave plate unit 330 and the polarizer unit 340 along the X-axis direction.

The λ/2 wave plate unit 330 and the polarizer unit 340 function as an output adjustment unit that adjusts the output (light intensity) of the laser light L. In addition, the λ/2 wave plate unit 330 and the polarizing plate unit 340 function as a polarization direction adjustment unit that adjusts the polarization direction of the laser light L. The details of these will be described later. The laser light L, which sequentially passes through the λ/2 wave plate unit 330 and the polarizer unit 340, is incident on the beam expander 350 along the X-axis direction.

The beam expander 350 collimates the laser light L while adjusting the diameter of the laser light L. The laser light L that passes through the beam expander 350 enters the mirror unit 360 along the X-axis direction.

The mirror unit 360 has a support base 361 and a plurality of mirrors 362 and 363. The support base 361 supports a plurality of mirrors 362 and 363. The support base 361 is mounted on the mounting base 301 so that its position can be adjusted along the X-axis direction and the Y-axis direction. The mirror 362 reflects the laser light (L) that has passed through the beam expander 350 in the Y-axis direction. The mirror 362 is mounted on the support base 361 so that the angle of its reflecting surface can be adjusted, for example, around an axis parallel to the Z axis. The mirror 363 reflects the laser light (L) reflected by the mirror 362 in the Z-axis direction. The mirror 363 is mounted on the support base 361 so that its reflecting surface can be angle-adjusted around an axis parallel to the X-axis and its position can be adjusted along the Y-axis direction, for example. The laser light L reflected by the mirror 363 passes through the opening 361a formed in the support base 361 and enters the laser concentrator 400 (see FIG. 1) along the Z-axis direction. That is, the direction of emission of the laser light L from the laser output unit 300 coincides with the moving direction of the laser light condensing unit 400. As described above, each mirror 362, 363 has a mechanism for adjusting the angle of the reflecting surface. In the mirror unit 360, the position adjustment of the support base 361 with respect to the mounting base 301, the position adjustment of the mirror 363 with respect to the support base 361, and the reflection surfaces of each mirror 362 and 363 are adjusted. By performing angle adjustment, the position and angle of the optical axis of the laser light L emitted from the laser output unit 300 are adjusted to the laser concentrator 400. That is, the plurality of mirrors 362 and 363 are configured to adjust the optical axis of the laser light L emitted from the laser output unit 300.

As shown in FIG. 4, the laser concentrator 400 has a housing 401. The housing 401 has a rectangular parallelepiped shape with the Y-axis direction as the longitudinal direction. A second movement mechanism 240 is mounted on one side 401e of the housing 401 (see FIGS. 5 and 7). In the housing 401, a cylindrical light incident portion 401a is provided so as to face the opening 361a of the mirror unit 360 in the Z-axis direction. The light incident unit 401a makes the laser light (L) emitted from the laser output unit 300 enter the housing 401. The mirror unit 360 and the light incident portion 401a are separated from each other by a distance at which they do not contact each other when the laser concentrator 400 is moved along the Z-axis direction by the second moving mechanism 240. .

As shown in FIGS. 5 and 6, the laser concentrator 400 has a mirror 402 and a dichroic mirror 403. In addition, the laser concentrator 400 includes a reflective spatial light modulator (spatial light modulator) 410, a 4f lens unit 420, a condenser lens unit 430, a drive mechanism 440, and a pair of It has a separate axis range sensor (displacement information acquisition unit) 450. The laser concentrator 400 radiates laser light (L) to the object 1 through the condenser lens unit 430.

The mirror 402 is mounted on the bottom surface 401b of the housing 401 so as to face the light incident portion 401a in the Z-axis direction. The mirror 402 reflects the laser light (L) incident into the housing 401 through the light incident unit 401a in a direction parallel to the XY plane. Laser light L collimated by the beam expander 350 of the laser output unit 300 is incident on the mirror 402 along the Z-axis direction. That is, the laser light L enters the mirror 402 along the Z-axis direction as parallel light. Therefore, even if the laser concentrator 400 is moved along the Z-axis direction by the second moving mechanism 240, the state of the laser light L incident on the mirror 402 along the Z-axis direction remains constant. maintain. The laser light L reflected by the mirror 402 is incident on the reflective spatial light modulator 410.

The reflective spatial light modulator 410 is mounted on the end 401c of the housing 401 in the Y-axis direction with the reflective surface 410a facing inside the housing 401. The reflective spatial light modulator 410 is, for example, a spatial light modulator (SLM: Spatial Light Modulator) of reflective liquid crystal (LCOS: Liquid Crystal on Silicon), and modulates the laser light (L) while modulating the laser light (L). ) is reflected in the Y-axis direction. The laser light L modulated and reflected by the reflective spatial light modulator 410 is incident on the 4f lens unit 420 along the Y-axis direction. Here, in a plane parallel to the XY plane, the optical axis of the laser light L incident on the reflective spatial light modulator 410 and the optical axis of the laser light L emitted from the reflective spatial light modulator 410 are The angle α formed is an acute angle (for example, 10 to 60°). That is, the laser light L is reflected at an acute angle along the XY plane in the reflective spatial light modulator 410. This is to suppress the decline in diffraction efficiency by suppressing the angle of incidence and reflection of the laser light L, and to fully demonstrate the performance of the reflective spatial light modulator 410.

The 4f lens unit 420 has a holder 421, a lens 422 on the reflective spatial light modulator 410 side, a lens 423 on the converging lens unit 430 side, and a slit member 424. there is. The holder 421 holds a pair of lenses 422 and 423 and a slit member 424. The holder 421 maintains the mutual positional relationship of the pair of lenses 422 and 423 and the slit member 424 in the direction along the optical axis of the laser light L constant. A pair of lenses 422 and 423 constitute a bilateral telecentric optical system in which the reflection surface 410a of the reflective spatial light modulator 410 and the entrance pupil surface 430a of the converging lens unit 430 are in an imaging relationship. there is. As a result, the image of the laser light L on the reflection surface 410a of the reflective spatial light modulator 410 (the image of the laser light L modulated in the reflective spatial light modulator 410) is, An image is transferred (image formed) on the entrance pupil surface 430a of the condenser lens unit 430. A slit 424a is formed in the slit member 424. The slit 424a is located between the lens 422 and the lens 423 and near the focal plane of the lens 422. An unnecessary portion of the laser light L modulated and reflected by the reflective spatial light modulator 410 is blocked by the slit member 424. The laser light L that passes through the 4f lens unit 420 enters the dichroic mirror 403 along the Y-axis direction.

The dichroic mirror 403 reflects most (e.g., 95 to 99.5%) of the laser light (L) in the Z-axis direction and reflects a portion (e.g., 0.5 to 5%) of the laser light (L). is transmitted along the Y-axis direction. Most of the laser light L is reflected at a right angle along the ZX plane in the dichroic mirror 403. The laser light L reflected by the dichroic mirror 403 enters the converging lens unit 430 along the Z-axis direction.

The condenser lens unit 430 is mounted on an end 401d (an end opposite to the end 401c) of the housing 401 in the Y-axis direction via a drive mechanism 440. The converging lens unit 430 has a holder 431 and a plurality of condensing lenses 432. The holder 431 holds a plurality of converging lenses 432. The plurality of condensing lenses 432 converge the laser light L on the object 1 (see FIG. 1) supported on the support 230. The drive mechanism 440 moves the converging lens unit 430 along the Z-axis direction using the driving force of the piezoelectric element.

The star-axis range sensor 450 is mounted on the end portion 401d of the housing 401 so as to be located on both sides of the converging lens unit 430 in the X-axis direction. The star-axis range sensor 450 uses the first measurement laser light (measurement laser light) to acquire displacement information that changes according to the displacement of the laser light incident surface of the object 1 (see FIG. 1). The star-axis ranging sensor 450 emits the first laser light for measurement to the laser light incident surface of the object 1 (see FIG. 1) supported on the support 230, and the first measurement laser light reflected by the laser light incident surface. 1 By receiving the laser light for measurement, displacement information on the laser light incident surface of the object 1 is acquired. Additionally, as the star-axis range sensor 450, sensors such as a triangulation method, a laser confocal method, a white confocal method, a spectral interference method, and an astigmatism method can be used.

The laser concentrator 400 has a beam splitter 461, a pair of lenses 462 and 463, and a camera 464 for monitoring the intensity distribution of the laser light L. The beam splitter 461 divides the laser light (L) transmitted through the dichroic mirror 403 into a reflection component and a transmission component. The laser light L reflected by the beam splitter 461 sequentially enters the pair of lenses 462 and 463 and the camera 464 along the Z-axis direction. A pair of lenses 462 and 463 constitute a bilateral telecentric optical system in which the entrance pupil surface 430a of the converging lens unit 430 and the imaging surface of the camera 464 are in an image forming relationship. As a result, the image of the laser light L on the entrance pupil surface 430a of the converging lens unit 430 is transferred (image formed) to the imaging surface of the camera 464. As described above, the image of the laser light L on the entrance pupil plane 430a of the condensing lens unit 430 is the image of the laser light L modulated in the reflective spatial light modulator 410. Therefore, in the laser processing device 200, the operating state of the reflective spatial light modulator 410 can be determined by monitoring the image capture result by the camera 464.

Additionally, the laser condenser 400 has a beam splitter 471, a lens 472, and a camera 473 for monitoring the optical axis position of the laser beam (L). The beam splitter 471 divides the laser light (L) that has passed through the beam splitter 461 into a reflection component and a transmission component. The laser light L reflected by the beam splitter 471 sequentially enters the lens 472 and the camera 473 along the Z-axis direction. The lens 472 focuses the incident laser light L onto the imaging surface of the camera 473.

A plurality of beam splitters 461 and 471 are arranged within the cylinder 404 extending along the Y-axis direction from the end 401d of the housing 401. A pair of lenses 462 and 463 are disposed within a cylinder 405 standing on the cylinder 404 along the Z-axis direction, and a camera 464 is disposed at an end of the cylinder 405. The lens 472 is disposed within a cylinder 406 standing on the cylinder 404 along the Z-axis direction, and the camera 473 is disposed at an end of the cylinder 406. The cylinder 405 and the cylinder 406 are arranged side by side in the Y-axis direction. In addition, the laser light L that passed through the beam splitter 471 may be absorbed by a damper provided at the end of the cylinder 404, etc., or may be used for an appropriate purpose.

As shown in FIGS. 6 and 7, the laser concentrator 400 includes a visible light source 481, a plurality of lenses 482, a reticle 483, a mirror 484, and a half mirror 485. It has a beam splitter 486, a lens 487, an observation camera (imaging unit) 488, and a coaxial range sensor 460. The visible light source 481 emits visible light (V) along the Z-axis direction. The plurality of lenses 482 collimate visible light (V) emitted from the visible light source 481. The reticle 483 provides a mark to visible light (V). The mirror 484 reflects visible light (V) collimated by the plurality of lenses 482 in the X-axis direction. The half mirror 485 divides the visible light (V) reflected by the mirror 484 into a reflection component and a transmission component. The visible light (V) reflected by the half mirror 485 sequentially passes through the beam splitter 486 and the dichroic mirror 403 along the Z-axis direction, passes through the converging lens unit 430, and passes through the support 230. ) is irradiated to the object 1 (see FIG. 1) supported on.

The visible light (V) irradiated to the object 1 is reflected by the laser light incident surface of the object 1, enters the dichroic mirror 403 through the condenser lens unit 430, and travels in the Z-axis direction. Therefore, it transmits through the dichroic mirror 403. The beam splitter 486 divides the visible light (V) transmitted through the dichroic mirror 403 into a reflection component and a transmission component. Additionally, the beam splitter 486 reflects the second measurement laser light L2 and its reflected light L2R, which will be described later. Visible light (V) passing through the beam splitter 486 passes through the half mirror 485 and sequentially enters the lens 487 and the observation camera 488 along the Z-axis direction. The lens 487 focuses the incident visible light (V) onto the imaging surface of the observation camera 488. The observation camera 488 images the laser light incident surface of the object 1. The observation camera 488 receives visible light (V) incident on the laser light incident surface via the reticle 483 and reflected from the laser light incident surface. In the laser processing apparatus 200, the state of the object 1 can be ascertained by observing the imaging result by the observation camera 488.

The mirror 484, half mirror 485 and beam splitter 486 are arranged in a holder 407 mounted on the end 401d of the housing 401. A plurality of lenses 482 and a reticle 483 are disposed in a cylinder 408 standing on a holder 407 along the Z-axis direction, and a visible light source 481 is disposed at an end of the cylinder 408. there is. The lens 487 is disposed within a cylinder 409 standing on a holder 407 along the Z-axis direction, and the observation camera 488 is disposed at an end of the cylinder 409. The cylinder 408 and the cylinder 409 are arranged in parallel with each other in the X-axis direction. In addition, the visible light (V) transmitted through the half mirror 485 along the X-axis direction and the visible light (V) reflected in the It may be absorbed into a damper, etc., or may be used for an appropriate purpose.

The coaxial range sensor 460 is mounted on the side of the holder 407. The coaxial range sensor 460 emits the second measurement laser light L2 to the laser light incident surface of the object 1 (see FIG. 1) supported on the support 230, and detects the laser light L2 according to the laser light incident surface. By detecting the reflected light L2R of the reflected second measurement laser light L2, displacement information on the laser light incident surface of the object 1 is acquired. The second measurement laser light L2 emitted from the coaxial range sensor 460 is reflected by the beam splitter 486, passes through the dichroic mirror 403, and is guided to the condenser lens unit 430. ) and is reflected from the laser light incident surface near the focus of the converging lens unit 430. The reflected light (L2R) returns to the coaxial range sensor 460 in a path opposite to that of the second measurement laser light (L2). The coaxial range sensor 460 acquires displacement information of the object 1 by utilizing the change in the state of the reflected light L2R depending on the position of the laser beam incident surface with respect to the converging lens unit 430. For example, as the coaxial range sensor 460, a sensor such as an astigmatism method can be used.

As shown in FIG. 8, the star-axis range sensor 450 includes a light-emitting element 451 such as a laser diode that emits the first measurement laser light L1, and a light-emitting element 451 such as a laser diode that emits the first measurement laser light L1, and It includes a linear photodiode array (light-receiving element array) 453 that receives the first measurement laser light (L1). The star-axis range sensor 450 is a triangulation sensor using a triangulation method. The laser light incident surface is, here, the back surface 1b of the object 1 (see FIG. 2).

In the star-axis range sensor 450, the first measurement laser light L1 is emitted from the light emitting element 451 along a direction inclined with respect to the Z-axis direction. The emitted first measurement laser light L1 is concentrated toward the object 1 via the lens 452 and reflected from the laser light incident surface. The reflected first measurement laser light L1 travels along a direction inclined with respect to the Z-axis direction and is focused toward the linear photodiode array 453 via the lens 454. ) is received at a spot position (SP).

The spot position (SP) (hereinafter simply referred to as “spot position (SP)”), which is the position of the light received in the linear photodiode array 453, has a unique relationship with the displacement of the laser light incident surface. . As a result, the separate-axis range sensor 450 acquires spot position information (light reception position information) corresponding to the spot position (light reception position) SP as displacement information. A plurality of linear photodiode arrays 453 may be provided.

Based on the imaging results by the observation camera 488, the control unit 500 operates the second movement mechanism 240 to move the laser concentrator 400 in the Z-axis direction to collect light on the laser beam incident surface. A first position alignment process is performed to adjust the position of the lens unit 430 (condenser lens 432) in the Z-axis direction to the initial height position. When adjusting the converging lens unit 430 to the initial height position through the first position alignment process, the control unit 500 adjusts the initial spot position (SP0), which is the spot position (SP) acquired from the star-axis range sensor 450. This information is recorded in the storage unit of the control unit 500 as initial spot position information.

The initial height position is the Z-axis position of the converging lens unit 430 (hereinafter referred to as “reticle”) when the mark of the reticle 483 is in focus on the image of the laser light incident surface captured by the observation camera 488. (also called “focus position”) (see FIG. 9). Here, the optical system is adjusted so that the focus of the mark of the reticle 483 is aligned with the laser light incident surface. In other words, the reticle focus position is the position when the focus of the mark of the reticle 483 is aligned with the laser light incident surface. In other words, the reticle focus position is the position of the converging lens unit 430 in the Z-axis direction when the focus of the converging lens unit 430 is on the laser incident surface.

Additionally, when the optical system is adjusted so that the focus of the mark on the reticle 483 is not on the laser light incident surface but on a height position a predetermined distance away from the laser light incident surface, the focus of the mark on the reticle 483 is correct. The position is not the laser light incident surface, but the height position that is a predetermined distance away from the laser light incident surface. When the control unit 500 cannot recognize the state in which the mark of the reticle 483 is in focus on the image of the laser light incident surface captured by the observation camera 488 as a result of executing the first position alignment process. Then, an unprocessable determination process is performed to determine that the object 1 cannot be processed.

The control unit 500 executes a received light amount adjustment process to adjust the star-axis range sensor 450 so that the received light amount in the linear photodiode array 453 is equal to or greater than the threshold value. Adjustments of the star-axis range sensor 450 include, for example, adjustments to increase at least one of the gain and exposure time, and adjustments to increase the output of the light emitting element 451.

Next, the main parts of this embodiment will be described in detail.

In this embodiment, laser processing can be performed on the object 1 provided on the laser beam incident surface (here, back surface 1b) with the transparent tape 101 (see FIG. 12). The transparent tape 101 is a tape-shaped transparent member that transmits light. That the transparent tape 101 has light transparency means that the light transparency of the transparent tape 101 is higher than that of parts of the object 1 other than the transparent tape 101. Having light transparency means, for example, that the laser light (L) and the first measurement laser light (L1) are transmitted, and specifically, the laser light (L) and the first measurement laser light (L1) are transmitted. ) means passing by maintaining this intensity. For example, having light transparency may mean, as an example, that the transmittance to the laser light L and the first measurement laser light L1 may be 85% or more. For example, the object 1 is a silicon through electrode (TSV) wafer with a thickness of 30 μm.

Connected to the control unit 500 is an input unit 701 (see FIG. 1) that receives input from the user. The input unit 701 is a user interface that displays and inputs various data. The input unit 701 constitutes a GUI (Graphical User Interface) with a graphic-based operation system. The input unit 701 is not particularly limited. The input unit 701 receives an input regarding the presence or absence of the transparent tape 101 on the object 1 from the user. The control unit 500 determines whether the transparent tape 101 is present on the laser beam incident surface of the object 1, for example, based on an input regarding the presence or absence of the transparent tape 101 from the input unit 701. do.

The control unit 500 stores a plurality of spot location information. Each of the plurality of spot position information is information about a plurality of different spot positions (SP). The plurality of spot position information is information acquired and stored by the modified region formation mode described later. When the control unit 500 determines that there is a transparent tape 101 on the laser beam incident surface of the object 1, it selects one of the plurality of stored spot position information in relation to the reference spot position (reference light receiving position). It is determined as reference spot position information (reference light reception position information). Specifically, in the modified region formation mode described later, the control unit 500 converts spot position information regarding the spot position SP acquired when forming a modified region whose depth position corresponds to the target depth position to a reference spot. It is decided based on location information. The control unit 500 stores the determined reference spot location information. The target depth position is a depth position at which a modified region is to be formed, and is also called a machining target position.

The determination of the reference spot position information by the control unit 500 may be made based on the results of internal observation of the object 1 on which the modified region has been formed by the modified region formation mode described later. Internal observation may be performed using, for example, an internal observation camera (not shown) such as an InGaAs camera that observes the inside of the object 1. Alternatively, the determination of the reference spot position information by the control unit 500 may be made based on the results of cutting and observing the object 1 on which the modified region has been formed by the modified region formation mode described later. The control unit 500 may determine the reference spot position information based on the user's selection using the input unit 701. Determination of reference spot position information by the control unit 500 can be realized by various methods and configurations using known technologies.

Then, the control unit 500 operates the second moving mechanism 240 to move the laser concentrator 400 in the Z-axis direction so that the spot position SP becomes the reference spot position of the reference spot position information, thereby moving the laser concentrator 400. A second position alignment process is performed to adjust the position of the condensing lens unit 430 in the Z-axis direction with respect to the light incident surface to a predetermined height position.

Additionally, when the control unit 500 determines that there is no transparent tape 101 on the laser beam incident surface of the object 1, after executing the first position alignment process, it operates the second movement mechanism 240. The laser concentrator 400 is moved in the Z-axis direction, and the position of the condenser lens unit 430 in the Z-axis direction with respect to the laser light incident surface is adjusted to a predetermined height position. When the position of the converging lens unit 430 in the Z-axis direction is set to a predetermined height position, the control unit 500 converts the spot position information regarding the spot position acquired from the star-axis range sensor 450 into a reference spot. It is stored in the control unit 500 as location information.

Next, an example of acquiring initial spot position information in the laser processing apparatus 200 will be described with reference to the flow chart in FIG. 10. Additionally, acquisition of the initial spot position information may be performed during initial adjustment, calibration, optical axis adjustment, or device shipment.

First, the object 1 is placed on the support 230. Here, an object 1 without a transparent tape 101 provided on the laser light incident surface is used. Based on the image of the laser light incident surface of the object 1 captured by the observation camera 488 (the image on which the reticle 483 is projected), the height position of the converging lens unit 430 matches the reticle focus position, The second moving mechanism 240 is driven by the control unit 500 to move the laser light focusing unit 400 in the Z-axis direction (step S1: first position alignment process).

For example, in step S1, images are acquired by the observation camera 488 at each Z-axis direction position of the condenser lens unit 430, image processing is performed on each image, and the reticle 483 is formed. A value (score) that is an indicator of contrast is calculated, and the position in the Z-axis direction of the laser concentrator 400 where the corresponding contrast value is maximized (peak) relative to the displacement in the Z-axis direction is determined as the reticle focus position. It is being done. Additionally, in step S1, an image processing method using pattern matching or Laplacian differentiation may be used.

Next, the control unit 500 determines whether the contrast score peak of the reticle 483 is optimal (step S2). For example, in step S2, NO is determined if the peak of the contrast value is not detected in step S1, and YES is determined if the peak is detected. If NO in step S2, it is determined that the in-focus state of the mark of the reticle 483 cannot be recognized on the image captured by the observation camera 488, and an error is determined (step S3). The control unit 500 determines that the object 1 on the support stand 230 cannot be processed, and the process ends (step S4).

In this embodiment, since the separate axis range sensor 450, which has a separate axis from the condenser lens unit 430, is used as a displacement information acquisition unit, for example, the optical axis of the separate axis range sensor 450 on the laser beam incident surface The position and the optical axis position of the condenser lens unit 430 are separated in the processing direction. Therefore, if YES in step S2, the first measurement laser light L1 is applied to the position where the reticle 483 is projected in step S1 on the laser light incident surface (e.g., the center position in the width direction of the street). The support 230 is moved in the horizontal direction so that the object 1 is moved in the horizontal direction (step S5). As an example, in the case where the position of the support stand 230 in the X-axis direction in step S1 is [ Assuming that the optical axis position is separated by α in the processing direction, in step S5, the support 230 is moved in the X-axis direction so that the position of the support 230 in the X-axis direction is [X0 + α]. Next, information on the initial spot position, which is the spot position (SP) detected by the linear photodiode array 453 of the star-axis range sensor 450, is recorded in the control unit 500 as initial spot position information (step S6). With the above, processing ends.

In addition, in steps S1 to S6, initial spot position information was acquired using the object 1 on which the transparent tape 101 was not provided on the laser light incident surface, but the transparent tape 101 was not provided on the laser light incident surface. Initial spot position information may be acquired using the object 1 provided with 101). In this case, bokeh appears in the mark of the reticle 483 due to the presence of the transparent tape 101 in the image of the observation camera 488 at the reticle focus position. Therefore, in this case, in step S1, the laser concentrator 400 can be moved in the Z-axis direction by driving the second moving mechanism 240 by the control unit 500 so that the bokeh generated is below a certain level or minimal. .

Next, an example of height setting using the laser processing apparatus 200 will be described with reference to the flow chart in FIG. 11.

First, the object 1 is placed on the support 230. The control unit 500 determines whether the transparent tape 101 is on the laser beam incident surface of the object 1 based on the input from the input unit 701 (step S11). In step S11, it may be determined whether the transparent tape 101 is on the laser beam incident surface, for example, from the image of the observation camera 488.

If YES in step S11, the first measurement laser light L1 is irradiated from the light-emitting element 451 of the star-axis range sensor 450 to the object 1 through the transparent tape 101, and the laser light incident surface is The first measurement laser light L1 reflected from passes through the transparent tape 101 and is received by the linear photodiode array 453. The second movement mechanism 240 is operated by the control unit 500 so that the spot position SP of the linear photodiode array 453 becomes the initial spot position SP0, and the condenser lens unit 430 is moved in the Z-axis direction. ) is moved (step S12).

Next, the control unit 500 determines whether the light amount of the first measurement laser light L1 received by the linear photodiode array 453 is optimal (step S13). If NO in step S13, the control unit 500 adjusts various parameters of the separate axis range sensor 450 and then returns to step S12 (step S14).

If YES in step S13, the modified region formation mode is executed to form a plurality of modified regions with different depth positions in the object 1, and each spot position information when forming the plurality of modified regions is stored. It is stored in the control unit 500. In the modified region formation mode, the process (process) of forming the modified region in a row inside the object 1 along the cutting line 5 is performed, including the depth position (position in the Z-axis direction) and the plane position of the modified region to be formed. In addition to changing the position (position in at least one of the X-axis direction and Y-axis direction) multiple times, spot position information regarding the spot position detected by the linear photodiode array 453 when forming each modified region It is stored in the control unit 500 (step S15 to step S18).

That is, in the modified region formation mode, the second moving mechanism 240 is operated by the control unit 500 to move the converging lens unit 430 in the Z-axis direction, and the focusing position of the laser light L is adjusted to the Z-axis. move in this direction (step S15). For example, in the first step S15, the converging lens unit 430 is moved in the Z-axis direction so that the converging position of the laser beam L is located on the opposite side to the laser beam incident surface side of the object 1. For example, in the second and subsequent steps S15, the converging lens unit 430 is moved in the Z-axis direction so that the converging position of the laser beam L moves by a predetermined amount toward the laser beam incident surface of the object 1.

The control unit 500 emits the laser light L from the laser concentrator 400 and operates the first moving mechanism 220 (see FIG. 1) to cut one line to be cut 5. Therefore, the focusing position of the corresponding laser light (L) is moved. As a result, a row of modified regions 7 is formed along the cutting line 5 (step S16). Spot position information regarding the spot position of the linear photodiode array 453 at this time is stored in the control unit 500 in relation to the modified region 7 (step S17). It is determined whether a certain number of spot position information or more is stored in the control unit 500 (step S18). If NO in step S18, the process returns to step S15.

Figures 12 and 13 are front views of the star-axis range sensor for explaining the modified region formation mode. As shown in FIG. 12, in the modified region formation mode, the converging lens unit 430 moves in the Z-axis direction so that the condensing position of the laser light L is on the opposite side to the laser light incident surface of the object 1. Located. In this state, the laser light L is irradiated from the laser concentrator 400 to form a modified area 7 on the object 1, and the laser light L is applied along one cutting line 5. The light converging position moves, thereby forming a row of modified regions 7 along the cutting line 5. Spot position information regarding the spot position SP1 of the linear photodiode array 453 at this time is stored in the control unit 500.

Next, in the modified region formation mode, the support 230 moves along at least one of the For example, it is changed to be located on a different cutting line 5. Next, as shown in FIG. 13, in the modified region formation mode, the converging lens unit 430 moves in the Z-axis direction, and the condensing position of the laser light L moves toward the laser light incident surface, where the thickness It is located in the central position of the direction. In this state, the laser light L is irradiated from the laser concentrator 400 to form a modified area 7 on the object 1, and the laser light L is applied along one cutting line 5. The light converging position moves, thereby forming a row of modified regions 7 along the cutting line 5. Spot position information regarding the spot position SP2 of the linear photodiode array 453 at this time is stored in the control unit 500.

If YES in step S18, the depth position of each formed modified region 7 is measured (step S19). For example, in step S19, the depth position of the modified region 7 may be measured by detecting the end of the modified region 7 using an internal observation camera (not shown) such as an InGaAs camera. For example, in step S19, the object 1 may be divided along the cutting line 5, and the depth position may be measured from the observation result of the cross section. Also, for example, in step S19, the depth position of the modified region 7 may be measured by half-cut margin inspection.

A half cut is a crack exposed from the modified area 7 to the front or back surface of the object 1. Half cut margin inspection is, for example, performing laser processing while varying the distance between the object 1 and the condenser lens unit 430 in the Z-axis direction (variable Z position), and measuring the incidence of laser light on the object 1. This is an inspection that confirms whether a crack has reached the surface or the surface opposite to the laser beam incident surface, and examines the critical value of the position of the modified region 7 in the Z-axis direction when the crack reaches the surface. When changing the Z position, the plane position of the condensing position of the laser light L is moved for each position in the Z-axis direction of the modified region 7 so that it is positioned on the cutting line 5 next to the first row, for example. (That is, sending the index one column at a time). In addition, the method and configuration for measuring the depth position of each formed modified region 7 are not particularly limited, and various known methods and configurations may be used.

Next, the control unit 500 determines which of the modified regions 7 of a certain number or more measured in step S19 whose depth position corresponds to the target depth position. Spot position (SP) when forming a specific modified region 7 (i.e., spot position (SP) when the depth position of the modified region 7 formed by irradiating the laser light L corresponds to the target depth position) It is set as a reference spot position, and information about this reference spot position is determined as reference spot position information. Corresponding to the target depth position is not limited to cases where it completely matches the target depth position, but also includes cases where it almost matches the target depth position, and cases where it approaches (closes within a certain distance) the target depth position. do. Then, the control unit 500 stores the determined reference spot position information (step S20).

In the example shown in FIGS. 14(a) to 14(h) , a plurality of modified regions 7 with different depth positions are formed in the object 1 by the modified region formation mode. Spot position information is associated with each of the plurality of modified regions 7 and stored in the control unit 500 . In this example, it is determined that the modified region 7 shown in Figure 14(d) is formed at a depth position corresponding to the target depth position 7N, and the modified region shown in Figure 14(d) The spot position SP when (7) is formed becomes the reference spot position, and information about the reference spot position is determined as the reference spot position information.

After step S20, the second movement mechanism 240 is operated by the control unit 500 so that the spot position SP becomes the reference spot position, and the Z-axis direction of the condensing lens unit 430 with respect to the laser light incident surface is moved. Set the position at a predetermined height position. The predetermined height position is an arbitrary height position corresponding to the target depth position of the modified region 7 formed in the object 1. With the above, the height set is completed and the process ends (step S21: second position alignment process).

On the other hand, in the case of NO in step S11, the second movement mechanism ( 240) is operated to move the converging lens unit 430 in the Z-axis direction (step S22). The control unit 500 determines whether the amount of light of the first measurement laser light L1 received by the linear photodiode array 453 is optimal (step S23). If NO in step S23, various parameters of the separate axis range sensor 450 are adjusted by the control unit 500, and then the process returns to step S22 (step S24).

If YES in step S23, the second moving mechanism 240 is operated by the control unit 500 to move the position of the converging lens unit 430 in the Z-axis direction to a predetermined height position (step S25). . The spot position acquired by the separate axis range sensor 450 is stored in the control unit 500 as a reference spot position (step S26). With the above, height setting is completed and the process ends (step S27).

In the above, the control unit 500 constitutes a storage unit, a decision unit, and a position alignment unit. The steps S15 to S18 constitute the first step, the steps S19 and S20 constitute the second step, and the step S21 constitutes the third step. In addition, there are cases where step S12 is not performed, and in this case, the modified region formation mode is executed while the reference height position is unknown.

However, in the triangulation method using the first measurement laser light (L1), the spot position (SP) of the linear photodiode array 453 and the optical axis direction (Z) of the converging lens unit 430 with respect to the laser light incident surface It is found that there is a certain correlation between the position in the axial direction and the position even when the transparent tape 101 is provided on the laser beam incident surface. In addition, in the triangulation method using the first measurement laser beam L1, if a transparent tape 101 is provided on the laser beam incident surface of the object 1, the transparent tape 101 is provided due to its presence. Compared to the case where it is not present, it is found that the optical path of the first measurement laser light L1 changes and the spot position SP changes.

Therefore, in the present embodiment, a plurality of spot position information is stored, and one of these that is relevant when setting the height is determined as reference spot position information based on, for example, internal observation results. Then, by operating the second movement mechanism 240 so that it becomes the reference spot position of the determined reference spot position information, it becomes possible to reliably perform height setting regardless of the observation of the laser beam incident surface by the observation camera 488. . That is, in this embodiment, even for the object 1 on which the transparent tape 101 is provided on the laser beam incident surface, the position of the condenser lens unit 430 in the optical axis direction with respect to the laser beam incident surface is reliably aligned. It becomes possible to do so. It is also possible to respond to the object 1 for which identification of the mark of the reticle 483 (see FIG. 7) is difficult. It is possible to eliminate the variation in the formation position of the modified area 7 due to the bokeh of the mark of the reticle 483 (see FIG. 7).

In the laser processing device 200 according to the present embodiment, the control unit 500 determines that the depth position of the modified region 7 formed by irradiating the laser light L by the laser concentrator 400 corresponds to the target depth position. The spot position information at this time is determined as reference spot position information. The laser processing method according to the present embodiment moves the laser concentrator 400 by the second moving mechanism 240 and then irradiates the laser light L by the laser concentrator 400 to the object 1. The step of forming the modified region 7 and acquiring spot position information by receiving the first measurement laser light L1 reflected from the laser light incident surface by the linear photodiode array 453 is performed using a second moving mechanism. Change the movement amount of (240) and repeat multiple times. Then, spot position information when the depth position of the formed modified region 7 corresponds to the target depth position is determined as reference spot position information. When the depth position of the modified region 7 formed in the object 1 corresponds to the target depth position, it is found that height setting is appropriately performed during laser processing. Therefore, in this embodiment, it is possible to determine spot position information when the depth position of the modified region 7 formed in the object 1 corresponds to the target depth position as reference spot position information related to height setting. I do it.

The laser processing device 200 according to this embodiment is provided with an input unit 701, and the control unit 500 determines whether there is a transparent tape 101 based on the input of the input unit 701. The laser processing method according to this embodiment includes a step of determining whether or not the transparent tape 101 is present based on the input from the input unit 701. This makes it possible to switch between the height set when the transparent tape 101 is provided on the laser beam incident surface and the height set when it is not provided, using the input of the input unit 701.

Figure 15(a) is a front view of the linear photodiode array 453 for explaining calculation of the spot position SP. FIG. 15(b) is an enlarged view of a portion of FIG. 15(a). As shown in Figures 15(a) and 15(b), when the first measurement laser light L1 incident on the linear photodiode array 453 passes through the transparent tape 101, Spherical aberration (bokeh when incident on the linear photodiode array 453) occurs. Therefore, the first measurement laser light L1 incident on the linear photodiode array 453 has diffusion properties in the incident area H compared to the case without the transparent tape 101.

Therefore, in this embodiment, even if the control unit 500 performs the center calculation on the amount of light received in the incident area H of the first measurement laser light L1 and obtains the position obtained as the spot position SP, do. As a result, even if the first measurement laser light L1 has diffusion properties, it becomes possible to obtain the spot position SP with high accuracy using the centroid calculation. In this embodiment using the triangulation method, it becomes possible to reduce the influence of the spherical aberration of the first measurement laser light L1 by deriving the spot position SP by centroid calculation in this way. In Fig. 15, for convenience of explanation, the distribution of the received light amount of the first measurement laser light L1 is shown as a waveform LB.

Although the embodiments have been described above, one aspect of the present disclosure is not limited to the above embodiments.

In the above embodiment, initial spot position information regarding the initial spot position SP0 is acquired (step S1 to step S6) during initial adjustment, etc., but the initial spot position SP0 does not need to be acquired. In this case, when setting the height, the above step S12 becomes unnecessary. Additionally, when initial spot position information is used as in the above embodiment, it becomes possible to suppress excessive deviation of the modified region 7 from the processing target position in the modified region formation mode and increase the tact.

In the laser processing apparatus 200 according to the above embodiment and the above modified example, the control unit 500 may store reference spot position information in association with each of the plurality of objects 1 . In the laser processing method according to the above embodiment and the above modified example, reference spot position information may be stored in association for each of a plurality of objects 1.

In this case, for example, when the object 1 on which height setting is actually performed is determined, reference spot position information stored in relation to it is acquired, and a second movement mechanism ( By operating 240, the position of the condensing lens unit 430 in the Z-axis direction with respect to the laser light incident surface can be adjusted to a predetermined height position. In other words, it becomes possible to automatically set height for each object 1. The object 1 for height setting can be identified, for example, through input from a user and recognition by a camera or the like.

In the laser processing apparatus 200 according to the above embodiment and the above modified example, the control unit 500 associates reference spot position information for each row of the plurality of modified regions 7 formed in one object 1. You can make it up and remember it. In the laser processing method according to the above embodiment and the above modified example, reference spot position information may be stored in association with each row of a plurality of modified regions 7 formed in one object 1.

In this case, for example, when forming the modified regions 7 in a row on one object 1, reference spot position information stored in relation to the corresponding modified region 7 of one object 1 is acquired, By operating the second moving mechanism 240 so that the spot position SP becomes the reference spot position, the position of the condensing lens unit 430 in the Z-axis direction with respect to the laser beam incident surface can be adjusted to a predetermined height position. there is. That is, it becomes possible to automatically perform height setting for each row (so-called processing pass) of a plurality of modified regions 7 formed in one object 1. One object 1 can be identified, for example, by input from a user and recognition by a camera or the like. The processing pass can be identified, for example, by the status of control by the control unit 500 and input from the user.

In the above-mentioned embodiment and the above-mentioned modification, confirmation of the depth position of the modified region 7 in the modified region formation mode (step S19) is not particularly limited as described above, and may be a destructive test or a non-destructive test. In the above embodiment and the above modified examples, the transparent member is not limited to the transparent tape 101, and may be other tape-shaped, film-shaped, layer-shaped, or block-shaped members. The transparent tape 101 may be transparent to the laser beam L and the first measurement laser beam L1, and may be colored. In the above embodiment and the above modification example, the object 1 in the case of acquiring initial spot position information may be a device wafer used as a product or a reference wafer for standard acquisition. Similarly, the object 1 on which height setting is performed may be a device wafer or a reference wafer.

In the above embodiment and the above modified example, the modified region 7 may be, for example, a crystal region, a recrystallization region, or a gettering region formed inside the object 1. The crystal region is a region that maintains the structure of the object 1 before processing. The recrystallized region is a region that was first evaporated, turned into plasma, or melted, and then solidified as a single crystal or polycrystal upon re-solidification. The gettering region is a region that exerts a gettering effect of collecting and trapping impurities such as heavy metals, and may be formed continuously or intermittently.

The above embodiment and the above modified example may be applied to processing such as trimming, slicing, and ablation. Each configuration in the above-described embodiments and modifications is not limited to the above-described materials and shapes, and various materials and shapes can be applied. Additionally, each configuration in the above-described embodiments and modifications can be arbitrarily applied to each configuration in other embodiments or modifications.

According to the present disclosure, a laser processing device and laser capable of reliably aligning the position of the condensing lens in the optical axis direction with respect to the laser beam incident surface even in an object in which a light-transmitting member is provided on the laser beam incident surface. It becomes possible to provide a processing method.

Claims (10)

A laser processing device in which a light-transmitting member irradiates laser light to an object provided on a laser light incident surface to form a modified region in the object, comprising:
A support portion supporting the object,
an irradiation unit that irradiates the laser light to the object through a condenser lens;
a triangulation sensor provided in the irradiation unit and having a light-receiving element array that receives the laser light for measurement reflected from the laser light incident surface;
a moving mechanism that moves at least one of the irradiation unit and the support unit along the optical axis direction of the condenser lens;
a storage unit that stores a plurality of light-receiving position information regarding the light-receiving position of the light-receiving element array;
a determination unit that determines one of the plurality of light reception position information stored in the storage unit as reference light reception position information;
The moving mechanism is operated to move at least one of the irradiation unit and the support unit so that the light receiving position of the light receiving element array is a light receiving position corresponding to the reference light receiving position information, so that the condenser lens with respect to the laser light incident surface is moved. A laser processing device comprising a position alignment unit that adjusts the position in the optical axis direction to a predetermined height position. In claim 1,
The decision section,
A laser processing device that determines the light-receiving position information when the depth position of the modified region formed by irradiating the laser light by the irradiation unit corresponds to a target depth position as the reference light-receiving position information. In claim 1 or claim 2,
A laser processing device wherein the storage unit stores the reference light-receiving position information in association with each of the plurality of objects. The method according to any one of claims 1 to 3,
A laser processing device wherein the storage unit stores the reference light-receiving position information in association with each row of the plurality of modified regions formed in one of the objects. The method according to any one of claims 1 to 4,
The light-receiving position of the light-receiving element array is a position obtained by performing a central calculation on the amount of light received in the area where the laser light for measurement is incident on the light-receiving element array. A laser processing method using a laser processing device in which a light-transmitting member irradiates laser light to an object provided on a laser light incident surface to form a modified region in the object, comprising:
The laser processing device,
A support portion supporting the object,
an irradiation unit that irradiates the laser light to the object through a condenser lens;
a triangulation sensor provided in the irradiation unit and having a light-receiving element array that receives the laser light for measurement reflected from the laser light incident surface;
A moving mechanism is provided to move at least one of the irradiation unit and the support unit along the optical axis direction of the condenser lens,
A first step of storing a plurality of light-receiving position information regarding the light-receiving position of the light-receiving element array;
A second step of determining one of the plurality of stored light-receiving position information as reference light-receiving position information;
The moving mechanism is operated to move at least one of the irradiation unit and the support unit so that the light receiving position of the light receiving element array is a light receiving position corresponding to the reference light receiving position information, so that the condenser lens with respect to the laser light incident surface is moved. A laser processing method comprising a third step of adjusting the position in the optical axis direction to a predetermined height position. In claim 6,
In the first step,
After moving at least one of the irradiation part and the support part by the moving mechanism, the laser light is irradiated by the irradiation part to form the modified region on the object, and the measurement laser is reflected from the laser light incident surface. The step of receiving light by the light-receiving element array and acquiring the light-receiving position information is repeated a plurality of times by changing the movement amount of the moving mechanism,
In the second step,
A laser processing method wherein the light-receiving position information when the depth position of the modified region formed in the first step corresponds to a target depth position is determined as the reference light-receiving position information. In claim 6 or claim 7,
A laser processing method in which, in the second step, the reference light-receiving position information is stored in association with each of the plurality of objects. The method according to any one of claims 6 to 8,
In the second step, the reference light-receiving position information is stored in association with each row of the plurality of modified regions formed in one object. The method according to any one of claims 6 to 9,
A laser processing method wherein the light-receiving position of the light-receiving element array is a position obtained by performing a central calculation on the amount of light received in the area where the laser light for measurement is incident in the light-receiving element array.

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