Laser processing apparatus and laser processing method

Abstract

A laser processing apparatus of the present application includes: a support section that supports an object including a glass substrate; a light source that emits laser light; a first optical section that imparts astigmatism to the laser light; a second optical section that condenses the laser light in a first region in a first direction perpendicular to an optical axis of the laser light, and condenses the laser light in a second region on a downstream side of the first region in a second direction perpendicular to the optical axis and the first direction; a moving section that relatively moves the second optical section with respect to the support section; an imaging section that acquires an image of a modified region; and a control section that controls the first optical section in a manner that each of a plurality of astigmatisms is imparted to the laser light, controls the moving section in a manner that the first region of the glass substrate is relatively moved along the second direction, and outputs the image of the modified region in association with each of the plurality of astigmatisms.

Description

Technical Field

[0001] This disclosure relates to laser processing apparatus and laser processing methods. Background Technology

[0002] A laser processing apparatus is known to form a modified region on an object by irradiating it with a laser (for example, see Japanese Patent Application Publication No. 2011-051011). Sometimes such a laser processing apparatus includes: a support for supporting the object, a light source for emitting laser light, a spatial light modulator for modulating the laser light emitted from the light source, and a focusing part for focusing the laser light modulated by the spatial light modulator. Summary of the Invention

[0003] In the laser processing apparatus described above, modified regions are sometimes formed along multiple lines on an object comprising a glass substrate by irradiating it with laser light. In such cases, ensuring sufficient bending strength is important for multiple chips obtained by cutting the object comprising the glass substrate along multiple lines. However, even laser processing conditions that can ensure sufficient bending strength for a particular laser processing apparatus may not always guarantee sufficient bending strength if those conditions are applied to other laser processing apparatuses of the same specifications.

[0004] The purpose of this disclosure is to provide a laser processing apparatus and a laser processing method that can ensure sufficient bending strength for multiple chips obtained by cutting an object including a glass substrate.

[0005] One aspect of this disclosure is a laser processing apparatus that forms a modified region on a glass substrate by irradiating an object, including a glass substrate, with a laser. The apparatus comprises: a support portion that supports the object; a light source that emits laser light; a first optical portion that imparts astigmatism to the laser emitted from the light source; a second optical portion that focuses the laser, imparted with astigmatism by the first optical portion, onto a first region in a first direction perpendicular to the optical axis of the laser, and onto a second region downstream of the first region in a second direction perpendicular to both the optical axis and the first direction; a moving portion that moves the second optical portion relative to the support portion; an imaging portion that acquires an image of the modified region; and a control portion that controls the first optical portion such that it imparts laser light to each of a plurality of different astigmatisms, controls the moving portion such that it moves relative to the first region of the glass substrate along a second direction, and outputs the image of the modified region acquired by the imaging portion in association with each of the plurality of astigmatisms.

[0006] One aspect of the laser processing method disclosed herein is a laser processing method for forming a modified region on a glass substrate by irradiating an object including a glass substrate with a laser, and includes: a first step of sequentially applying a laser to each of a plurality of different astigmatisms to acquire an image of the modified region, wherein the modified region is formed on the glass substrate by irradiation with the lasers applied to each of the plurality of astigmatisms; and a second step of associating the image of the modified region with each of the plurality of astigmatisms, wherein in the first step, the lasers applied to each of the plurality of astigmatisms are focused on a first region in a first direction perpendicular to the optical axis of the laser, and focused on a second region downstream of the first region in a second direction perpendicular to both the optical axis and the first direction, and the first region is moved relative to the glass substrate along the second direction. Attached Figure Description

[0007] Figure 1 This is a structural diagram of a laser processing apparatus according to one implementation method.

[0008] Figure 2 yes Figure 1 A cross-sectional view of a portion of the spatial light modulator shown.

[0009] Figure 3 This is a top view of a glass substrate, which is the object of one embodiment.

[0010] Figure 4 It is shown in Figure 1 The image shown is a diagram of an astigmatic pattern displayed by a spatial light modulator.

[0011] Figure 5 It is shown that Figure 1 The diagram shown illustrates the optical path of an astigmatic laser given by a spatial light modulator.

[0012] Figure 6 It is shown that Figure 1 The diagram shows the shape of the first region of the astigmatic laser given by the spatial light modulator.

[0013] Figure 7 It is shown Figure 1 The diagram shows the display status and input acceptance status of the interface section.

[0014] Figure 8 This is an image showing the modified region formed on the glass substrate.

[0015] Figure 9 This is a diagram showing the bending strength of multiple chips obtained by cutting a glass substrate.

[0016] Figure 10 It is a graph showing the relationship between the astigmatism and the modified region of each condenser lens unit.

[0017] Figure 11 It is a graph showing the relationship between the astigmatism and the modified area of ​​each laser processing device.

[0018] Figure 12 It is a graph showing the relationship between the astigmatism and the modified region of each glass material. Detailed Implementation

[0019] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Furthermore, in each drawing, the same or equivalent parts are labeled with the same symbols, and repeated descriptions are omitted.

[0020] [Structure of laser processing equipment]

[0021] like Figure 1 As shown, the laser processing apparatus 1 includes: a support unit 2, a light source 3, an optical axis adjustment unit 4, a spatial light modulator (first optical unit) 5, a focusing unit (second optical unit) 6, a moving unit 7, a visible imaging unit (imaging unit) 8, an infrared imaging unit 9, and a control unit 10. The laser processing apparatus 1 is a device that forms a modified region 12 on an object 11 by irradiating it with a laser beam L. In the following description, the three mutually orthogonal directions are referred to as the X direction, Y direction, and Z direction. In this embodiment, the X direction is a first horizontal direction, the Y direction is a second horizontal direction perpendicular to the first horizontal direction, and the Z direction is a vertical direction.

[0022] The support portion 2 supports the object 11. As an example, the support portion 2 supports the object 11 by adsorbing and pasting a film (not shown) onto the object 11, such that the surface 11a of the object 11 is orthogonal to the Z direction. The support portion 2 can move along various directions in the X and Y directions, and can rotate about an axis parallel to the Z direction.

[0023] Light source 3 emits laser L. As an example, light source 3 emits laser L via pulse oscillation. Laser L is transmissive relative to object 11.

[0024] The optical axis adjustment unit 4 adjusts the optical axis of the laser L emitted from the light source 3. In this embodiment, the optical axis adjustment unit 4 changes the travel direction of the laser L emitted from the light source 3 to the Z-direction and adjusts the optical axis of the laser L. The optical axis adjustment unit 4 is, for example, composed of multiple reflectors whose position and angle can be adjusted.

[0025] A spatial light modulator 5 is disposed within the frame H. The spatial light modulator 5 modulates the laser L emitted from the light source 3. In this embodiment, the laser L, which travels downward along the Z direction from the optical axis adjustment section 4, is incident within the frame H. The laser L incident within the frame H is horizontally reflected by the mirror M1 at an angle relative to the Y direction. The laser L reflected by the mirror M1 is then incident on the spatial light modulator 5. The spatial light modulator 5 horizontally reflects and modulates the incident laser L along the Y direction.

[0026] A focusing unit 6 is mounted on the bottom wall of the frame H. The focusing unit 6 focuses the laser L modulated by the spatial light modulator 5 onto the object 11 supported by the support unit 2. In this embodiment, the laser L, horizontally reflected by the spatial light modulator 5 along the Y direction, is reflected downwards along the Z direction by the dichroic mirror M2, and the laser L reflected by the dichroic mirror M2 is incident on the focusing unit 6. The focusing unit 6 focuses this incident laser L along the Z direction from the surface 11a side onto the object 11. In this embodiment, the focusing unit 6 is constructed by mounting a focusing lens unit 61 on the bottom wall of the frame H via a drive mechanism 62. The focusing lens unit 61 has the function of focusing parallel light to a point on the optical axis. The drive mechanism 62 moves the focusing lens unit 61 along the Z direction, for example, by the driving force of a piezoelectric element.

[0027] Furthermore, within the frame H, an imaging optical system (not shown) is arranged between the spatial light modulator 5 and the focusing section 6. This imaging optical system is a telecentric optical system positioned on either side of the reflecting surface of the spatial light modulator 5 and the entrance pupil surface of the focusing section 6 in an imaging relationship. Consequently, the image of the laser L on the reflecting surface of the spatial light modulator 5 (the image of the laser L modulated by the spatial light modulator 5) is similarly imaged onto the entrance pupil surface of the focusing section 6.

[0028] A pair of range sensors S1 and S2 are mounted on the bottom wall of the frame H in the X direction on both sides of the condenser lens unit 61. Each range sensor S1 and S2 obtains displacement data of the surface 11a by emitting range-measuring light (e.g., laser) onto the surface 11a of the object 11 and detecting the range-measuring light reflected from the surface 11a.

[0029] The moving part 7 moves the focusing part 6 relative to the support part 2. The moving part 7 is a moving mechanism (including an actuator, motor, or other drive source) that moves the focusing part 6 relative to the support part 2 by moving at least one of the frame H and the support part 2. In this embodiment, the moving part 7 moves the support part 2 along the X and Y directions, rotates the support part 2 about an axis parallel to the Z direction, and moves the frame H along the Z direction.

[0030] A visible camera unit 8 is disposed within the frame H. The visible camera unit 8 emits visible light V and acquires an image of the object 11 formed by the visible light V as an image. In this embodiment, the visible light V emitted from the visible camera unit 8 is irradiated onto the surface 11a of the object 11 via the dichroic mirror M2 and the focusing unit 6, and the visible light V reflected from the surface 11a is detected by the visible camera unit 8 via the focusing unit 6 and the dichroic mirror M2.

[0031] An infrared camera 9 is mounted on the side wall of the frame H. The infrared camera 9 emits infrared light and acquires an image of the object 11 formed by the infrared light as an image. In this embodiment, the frame H and the infrared camera 9 can move integrally along the Z direction.

[0032] The control unit 10 controls the operation of each part of the laser processing apparatus 1. The control unit 10 includes a processing unit 101, a storage unit 102, and an interface unit (display unit, input receiving unit) 103. The processing unit 101 is configured as a computer device including a processor, memory, storage device, and communication equipment. In the processing unit 101, the processor executes software (programs) loaded into memory, etc., controls the reading and writing of data in memory and storage device, and performs communication via the communication device. The storage unit 102 is, for example, a hard disk, which stores various types of data. The interface unit 103 displays various data to the operator and receives various data input from the operator. In this embodiment, the interface unit 103 is configured as a GUI (Graphical User Interface).

[0033] In the laser processing apparatus 1 configured as described above, if the laser L is focused inside the object 11, the portion of the laser L corresponding to the focusing point C is absorbed, forming a modified region 12 inside the object 11. The modified region 12 is a region whose density, refractive index, mechanical strength, and other physical properties differ from the surrounding unmodified region. Examples of modified regions 12 include: melt-processed regions, cracked regions, insulation-damaged regions, and regions with refractive index changes. The modified region 12 has the characteristic that cracks easily extend from the modified region 12 towards the incident side of the laser L and the opposite side. This characteristic of the modified region 12 is used for cutting the object 11.

[0034] As an example, the operation of the laser processing apparatus 1 in the case where a modified region 12 is formed inside the object 11 along the line 15 used to cut the object 11 will be described.

[0035] First, the laser processing apparatus 1 rotates the support 2 about an axis parallel to the Z direction, with the line 15 set on the object 11 parallel to the X direction. Next, based on images acquired by the infrared camera 9 (e.g., an image of the functional element layer of the object 11), the laser processing apparatus 1 moves the support 2 along various directions in the X and Y directions, such that the focusing point C of the laser L is located on the line 15 when viewed from the Z direction.

[0036] Next, based on the image acquired by the visible camera unit 8 (e.g., an image of the surface 11a of the object 11), the laser processing apparatus 1 moves the frame H (i.e., the focusing part 6) along the Z direction such that the focusing point C of the laser L is located on the surface 11a. Then, using this position as a reference, the laser processing apparatus 1 moves the frame H (i.e., the focusing part 6) along the Z direction such that the focusing point C of the laser L is located at a predetermined depth from the surface 11a.

[0037] Next, the laser processing apparatus 1 moves the support 2 along the X direction such that the laser L emitted from the light source 3 moves relative to the focal point C of the laser L along the line 15. At this time, the laser processing apparatus 1, based on the displacement data of the surface 11a obtained by the distance sensor located on the front side (the front side relative to the direction of relative movement of the laser L relative to the object 11) of the pair of distance sensors S1 and S2, activates the drive mechanism 62 of the focusing part 6 such that the focal point C of the laser L is located at a predetermined depth from the surface 11a.

[0038] As described above, a series of modified regions 12 are formed along line 15 at a constant depth from the surface 11a of the object 11. If a laser L is emitted from the light source 3 via pulse oscillation, multiple modified points 12s are formed into a series along the X direction. A modified point 12s is formed by irradiation with a single pulse of laser L. A series of modified regions 12 is a collection of multiple modified points 12s arranged in a series. Adjacent modified points 12s are sometimes connected and sometimes separated depending on the pulse spacing of the laser L (the value obtained by dividing the relative moving speed of the focusing point C of the object 11 by the repetition frequency of the laser L).

[0039] [Structure of a spatial light modulator]

[0040] The spatial light modulator 5 in this embodiment is a reflective liquid crystal on silicon (LCOS) spatial light modulator (SLM). Figure 2As shown, the spatial light modulator 5 is constructed by sequentially stacking a driving circuit layer 52, a pixel electrode layer 53, a reflective film 54, an alignment film 55, a liquid crystal layer 56, an alignment film 57, a transparent conductive film 58, and a transparent substrate 59 on a semiconductor substrate 51.

[0041] The semiconductor substrate 51 is, for example, a silicon substrate. The driving circuit layer 52 forms an active matrix circuit on the semiconductor substrate 51. The pixel electrode layer 53 includes a plurality of pixel electrodes 53a arranged in a matrix along the surface of the semiconductor substrate 51. Each pixel electrode 53a is formed, for example, from a metal material such as aluminum. A voltage is applied to each pixel electrode 53a through the driving circuit layer 52.

[0042] The reflective film 54 is, for example, a dielectric multilayer film. An alignment film 55 is disposed on the surface of the liquid crystal layer 56 on the side of the reflective film 54, and an alignment film 57 is disposed on the surface of the liquid crystal layer 56 opposite to the reflective film 54. Each alignment film 55 and 57 is formed, for example, from a polymer material such as polyimide, and a rubbing treatment is performed, for example, on the contact surfaces between each alignment film 55 and 57 and the liquid crystal layer 56. The alignment films 55 and 57 align the liquid crystal molecules 56a contained in the liquid crystal layer 56 in a certain direction.

[0043] A transparent conductive film 58 is disposed on the surface of the transparent substrate 59 on the side of the alignment film 57, facing the pixel electrode layer 53 across the liquid crystal layer 56, etc. The transparent substrate 59 is, for example, a glass substrate. The transparent conductive film 58 is formed of, for example, a light-transmitting and conductive material such as ITO. The transparent substrate 59 and the transparent conductive film 58 allow laser L to pass through.

[0044] In the spatial light modulator 5 configured as described above, if a signal representing a modulation pattern is input from the control unit 10 to the drive circuit layer 52, a voltage corresponding to that signal is applied to each pixel electrode 53a, forming an electric field between each pixel electrode 53a and the transparent conductive film 58. When this electric field is formed, the alignment direction of the liquid crystal molecules 216a in each region corresponding to each pixel electrode 53a changes, and the refractive index in each region corresponding to each pixel electrode 53a changes. This state is characterized by a modulation pattern being displayed on the liquid crystal layer 56.

[0045] When a modulation pattern is displayed on the liquid crystal layer 56, if laser L is incident on the liquid crystal layer 56 from the outside via the transparent substrate 59 and the transparent conductive film 58, reflected by the reflective film 54, and exited from the liquid crystal layer 56 to the outside via the transparent conductive film 58 and the transparent substrate 59, then laser L is modulated according to the modulation pattern displayed on the liquid crystal layer 56. Thus, according to the spatial light modulator 5, the modulation of laser L (e.g., modulation of the intensity, amplitude, phase, polarization, etc. of laser L) can be performed by appropriately setting the modulation pattern displayed on the liquid crystal layer 56.

[0046] [Structure of the object]

[0047] like Figure 3 As shown, the object 11 in this embodiment is a glass substrate 20. As an example, the glass substrate 20 is formed into a rectangular plate shape from synthetic quartz glass, alkali-free glass, borosilicate glass, etc. In addition to the glass substrate 20, the object 11 in this embodiment may also have other layers (e.g., a film formed on at least one main surface of the glass substrate 20).

[0048] Laser L is irradiated along each of the plurality of lines 15 on the glass substrate 20. As a result, modified regions 12 are formed on each of the plurality of lines 15 on the glass substrate 20. In this embodiment, the modified regions 12 are formed on the glass substrate 20 such that the entire modified region 12 is located inside the glass substrate 20. Alternatively, the modified regions 12 may be formed on the glass substrate 20 such that a portion of the modified region 12 is exposed to the outside.

[0049] The glass substrate 20, on which the modified region 12 is formed, is cut into multiple chips along multiple lines 15 by cracking extending from the modified region 12 toward the incident side of the laser L and the opposite side. In this embodiment, when viewed from the thickness direction of the glass substrate 20, the multiple lines 15 are arranged in a grid pattern. Each line 15 is a virtual line set on the glass substrate 20 by the laser processing apparatus 1. Alternatively, each line 15 may be an actual line leading to the glass substrate 20.

[0050] [Functions of the Control Department]

[0051] like Figure 4 As shown, the control unit 10 inputs a signal representing the astigmatic pattern AS to the spatial light modulator 5. As a result, the astigmatic pattern AS is displayed on the liquid crystal layer 56 of the spatial light modulator 5, imparting astigmatism to the laser L incident on the focusing unit 6. In this embodiment, the laser L oscillates from the light source 3 using burst plus pulses of an ultrashort pulse laser.

[0052] If the laser L, which has been given astigmatism by the spatial light modulator 5, is incident on the focusing section 6, then as Figure 5 As shown, the laser L is focused by the focusing lens unit 61 into a first region R1 in the Y direction (a first direction perpendicular to the optical axis of the laser L), and into a second region R2 in the X direction (a second direction perpendicular to both the optical axis of the laser L and the first direction). The second region R2 is located downstream of the first region R1 in the direction of travel of the laser L. Furthermore, in Figure 5 The optical components disposed between the spatial light modulator 5 and the focusing part 6 are omitted from the illustration.

[0053] In this state, the control unit 10 controls the moving unit 7 to move relative to the first region R1 of the glass substrate 20 along the X direction. As a result, the modified region 12 is formed on the glass substrate 20 along the X direction. Then, the control unit 10 controls the visible imaging unit 8 to acquire an image of the modified region 12 formed on the glass substrate 20.

[0054] Based on the above, the control unit 10 functions as follows in the laser processing condition determination mode. The laser processing condition determination mode is a mode that determines the laser processing conditions used to form the preferred modified region 12 when cutting the glass substrate 20 into multiple chips. Furthermore, the laser processing method implemented in the laser processing condition determination mode is equivalent to the laser processing method of this embodiment.

[0055] First, the control unit 10 controls the spatial light modulator 5 to sequentially apply laser L to each of a plurality of different astigmatisms, and controls the visible imaging unit 8 to acquire an image of the modified region 12 (first step). The modified region 12 is formed on the glass substrate 20 by irradiation with laser L applied to each of the plurality of astigmatisms. In each state where laser L is applied to each of the plurality of astigmatisms, the control unit 10 controls the moving unit 7 to move relative to each other in the first region R1 of the glass substrate 20 along the X direction. As a result, the modified region 12 corresponding to the astigmatism is formed on the glass substrate 20.

[0056] In the first step, the control unit 10 inputs a signal representing each of the plurality of astigmatic patterns AS corresponding to each of the plurality of astigmatisms into the spatial light modulator 5. For example... Figure 6 As shown, each of the multiple astigmatic patterns AS is such that the X direction ( Figure 6 The width of the first region R1 in the left-right direction (center) divided by the width in the Y direction ( Figure 6 Astigmatic patterns with different width values ​​(hereinafter referred to as "ellipticity") of the first region R1 in the vertical direction. The case where the ellipticity of the first region R1 is 1 is the case where the astigmatic pattern AS is not input to the spatial light modulator 5, that is, the case where astigmatism is not imparted to the laser L. Figure 6 In the case of an ellipticity of 1, the diameter of the first region R1 is, for example, 1 μm. Furthermore, the shape of the first region R1, which is imparted with astigmatism by the laser L, is not limited to a perfectly elliptical shape; for example, it can also be a flat circle, an oblong shape, etc.

[0057] After the first step, the control unit 10 associates the image of the modified region 12 acquired by the visible camera unit 8 with each of the plurality of astigmatisms (in other words, correspondingly) (second step). After the second step, the control unit 10 sets any one of the plurality of astigmatisms associated with the image of the modified region 12 as the laser processing condition (third step). In this embodiment, as... Figure 7 As shown, the interface 103 displays the image of the modified region 12 (the image of the modified region 12 as viewed from the thickness direction of the glass substrate 20) acquired by the visible camera 8 and multiple astigmatism ( Figure 7 The ellipticity (in the middle) is displayed in relation to each other, and multiple astigmatisms are accepted. Figure 7 The input of any one of the ellipticity values ​​is used as the laser processing condition.

[0058] exist Figure 7 In one example shown, the greater the ellipticity of the first region R1 (in other words, the stronger the astigmatism imparted to the laser L), the more the direction of the crack extending from the modified region 12 is along the X direction. Figure 7 The trend is in the left-right direction (center). Figure 7 In one example shown, the black dot-like areas correspond to modification points, and the black line-like areas extending from the modification points correspond to cracks. If the direction of the cracks extending from the modification area 12 is along the X direction (i.e., if the direction of the cracks is along the direction of the line 15), sufficient bending strength can be easily ensured for multiple chips obtained by cutting the glass substrate 20. Therefore, the operator selects an image with the crack direction along the X direction for the modification area 12, and then considers the astigmatism associated with that image. Figure 7 The ellipticity (in the middle) is used as the laser processing condition input control unit 10. Furthermore, bending strength refers to the destructive stress (stress at which the chip breaks) obtained through a bending strength measurement test. The bending strength measurement test involves placing a chip on two parallel first cylinders, and in this state, applying a downward external force to the chip using two second cylinders arranged parallel to each other with a narrower interval than the two first cylinders, and measuring the stress at which the chip breaks (four-point bending test).

[0059] [Functions and Effects]

[0060] In the laser processing apparatus 1 and the laser processing method implemented in the laser processing apparatus 1, each of a plurality of different astigmatisms is sequentially applied to a laser L, and an image of the modified region 12 formed on the glass substrate 20 by the irradiation of the laser L is output in association with each of the plurality of astigmatisms. Here, if the first region R1 of the laser L focused in the Y direction is moved relative to the glass substrate 20 along the X direction, there is a tendency for the direction of the crack extending from the modified region 12 to stabilize. In addition, if the direction of the crack extending from the modified region 12 is along the X direction, sufficient bending strength can be easily ensured for the plurality of chips obtained by cutting the glass substrate 20. Therefore, by applying the laser L to the astigmatism associated with the image of the modified region 12 with the crack direction along the X direction, laser processing conditions that can stably ensure sufficient bending strength can be achieved. Thus, the laser processing apparatus 1 and the laser processing method implemented in the laser processing apparatus 1 can ensure sufficient bending strength for the plurality of chips obtained by cutting the glass substrate 20. Furthermore, the image of the modified region 12 is output in association with each of the multiple astigmatisms, not limited to displaying them on the interface 103, but also including storing them in a storage device such as memory.

[0061] In the laser processing apparatus 1, the control unit 10 inputs a signal representing each of the multiple astigmatic patterns AS corresponding to each of the multiple astigmatisms into the spatial light modulator 5. This allows for easy and reliable application of laser light to each of the multiple, distinct astigmatisms.

[0062] In the laser processing apparatus 1, each of the plurality of astigmatic patterns AS is an astigmatic pattern in which the width of the first region R1 in the X direction divided by the width of the first region R1 in the Y direction yields a different value. Therefore, each of the plurality of different astigmatic patterns can be easily and reliably applied to the laser L.

[0063] In the laser processing apparatus 1, the control unit 10 includes an interface unit 103 that displays an image of the modified region 12 acquired by the visible camera unit 8 in association with each of a plurality of astigmatisms. This allows the operator to objectively identify the relationship between astigmatism and the modified region 12.

[0064] In the laser processing apparatus 1, the control unit 10 includes an interface unit 103 that accepts input of any one of a plurality of astigmatisms as laser processing conditions. Thus, the operator can set an appropriate astigmatism as the laser processing condition.

[0065] [Experimental Results]

[0066] Figure 8(a) is an image of the modified region formed on a 500 μm thick glass substrate made of alkali-free glass by irradiation with a laser that does not impart astigmatism (image of the modified region as viewed from the thickness direction of the glass substrate). Figure 8 (b) is an image of the modified region formed on a 500 μm thick glass substrate made of alkali-free glass by irradiation with a laser imparting an ellipticity of 1.61 (an image of the modified region viewed from the thickness direction of the glass substrate). Figure 8 (a) and Figure 8 In (b), except for whether or not astigmatism is imparted to the laser, the laser processing conditions are set to be the same as follows. Figure 8 The results of (a) and (b) show that if a laser with astigmatism is applied in the Y direction ( Figure 8 The light is focused on the first region along the X direction (vertical direction), and this first region is on the glass substrate along the X direction (vertical direction). Figure 8 When the center (in the left-right direction) moves relatively, the direction of the cracks extending from the modified region stabilizes along the X direction. Furthermore, the laser processing conditions are as follows.

[0067] Laser wavelength: 1028nm

[0068] Laser pulse width: 300 fs

[0069] Laser repetition frequency: 50kHz

[0070] The relative movement speed of the laser relative to the glass substrate: 500 mm / s

[0071] Laser energy: 2μJ

[0072] Distance from the laser incident surface of the glass substrate to the modified area: 80 μm

[0073] Figure 9 (a) is a graph showing the bending strength of multiple chips obtained by forming a modified region on a glass substrate of 200 μm thickness made of fluorophosphate glass through irradiation with a laser that has not been imparted with astigmatism. Figure 9 (b) is a graph showing the bending strength of multiple chips obtained by irradiation with a laser imparting an astigmatism of 1.61, in which a modified region is formed on a glass substrate of 200 μm thickness made of fluorophosphate glass. Figure 9 (a) and Figure 9 In (b), except for whether or not the laser imparts astigmatism, the laser processing conditions are set to be the same, and the chip size, viewed from the thickness direction, is also set to be the same at 5mm × 7mm. Figure 9In (a) and (b), "incident surface pressing" means applying a load to the chip from the surface (incident surface) of the chip on which the laser is incident, and "backside pressing" means applying a load to the chip from the backside (the surface opposite to the incident surface). Figure 9 The results in (a) and (b) show that when a modified region is formed in the glass substrate by irradiation with a laser that does not impart astigmatism, the breaking stress representing bending strength is inconsistent. In contrast, when a modified region is formed in the glass substrate by irradiation with a laser that imparts astigmatism, the breaking stress representing bending strength remains stable at a high value. Furthermore, the laser processing conditions are as follows.

[0074] Laser wavelength: 1028nm

[0075] Laser pulse width: 300 fs

[0076] Laser repetition frequency: 50kHz

[0077] The relative movement speed of the laser relative to the glass substrate: 400 mm / s

[0078] Laser energy: 7μJ

[0079] Distance from the laser incident surface of the glass substrate to the modified area: 100 μm

[0080] Figure 10 This is a diagram showing the relationship between the astigmatism and the modified region image (image of the modified region when viewed from the thickness direction of the glass substrate) of each condenser lens unit. Figure 10 The results show that for modified regions formed on glass substrates by irradiation with a laser that does not impart astigmatism (irradiation with a laser having an ellipticity of 1), the direction of cracks extending from the modified regions varies depending on the condenser lens unit. Conversely, for modified regions formed on glass substrates by irradiation with a laser that imparts astigmatism of 1.03 to 1.08, the closer the ellipticity is to 1.08, the more stable the direction of cracks extending from the modified regions is along the X-direction. Figure 10 The state of (left and right directions in the middle).

[0081] Figure 11 This is a graph showing the relationship between astigmatism and the modified region in each laser processing apparatus (images of the modified region viewed from the thickness direction of the glass substrate). From Figure 11The results show that for modified regions formed on glass substrates by irradiation with a laser that does not impart astigmatism (irradiation with a laser having an ellipticity of 1), the direction of cracks extending from the modified regions varies depending on the laser processing apparatus. Conversely, for modified regions formed on glass substrates by irradiation with a laser that imparts astigmatism of 1.08 to 1.6, the closer the ellipticity is to 1.6, the more stable the direction of cracks extending from the modified regions is along the X-direction. Figure 11 The state of (left and right directions in the middle).

[0082] Figure 12 This is a diagram showing the relationship between astigmatism and the modified region in each glass material (images of the modified region viewed from the thickness direction of the glass substrate). Figure 12 The results show that for modified regions formed on glass substrates by irradiation with a laser that does not impart astigmatism (irradiation with a laser having an ellipticity of 1), the direction of cracks extending from the modified regions is inconsistent regardless of the glass material. Conversely, for modified regions formed on glass substrates by irradiation with a laser that imparts astigmatism of 1.04–1.6, the closer the ellipticity is to 1.6, the more stable the direction of cracks extending from the modified regions is along the X-direction. Figure 12 The state of (center) is in the left and right direction.

[0083] [Variation Example]

[0084] This disclosure is not limited to the embodiments described above. For example, the first optical unit that imparts astigmatism to the laser L emitted from the light source 3 is not limited to the spatial light modulator 5. As an example, the first optical unit may also be an optical system including a cylindrical lens that can move along the optical axis. However, by simply displaying a slit pattern in the spatial light modulator 5 or configuring a mechanical slit to make the cross-sectional shape of the laser L perpendicular to the optical axis elongated in the focusing region, it is difficult to stabilize the direction of the cracks extending from the modified region 12.

[0085] The display unit that displays the image of the modified region 12 in association with each of the multiple astigmatisms is not limited to the interface unit 103, but may also be a display or the like that provided separately from the control unit 10. The input receiving unit that accepts input from any one of the multiple astigmatisms as laser processing conditions is not limited to the interface unit 103, but may also be a mouse, keyboard or the like that provided separately from the control unit 10.

[0086] In the above embodiments, the X direction is a first horizontal direction, the Y direction is a second horizontal direction perpendicular to the first horizontal direction, and the Z direction is a vertical direction. However, the X, Y, and Z directions are not limited to these directions. For example, the Z direction can also be a direction that intersects the vertical direction.

[0087] One aspect of this disclosure is a laser processing apparatus that forms a modified region on a glass substrate by irradiating an object, including a glass substrate, with a laser. The apparatus comprises: a support portion that supports the object; a light source that emits laser light; a first optical portion that imparts astigmatism to the laser emitted from the light source; a second optical portion that focuses the laser, imparted with astigmatism by the first optical portion, onto a first region in a first direction perpendicular to the optical axis of the laser, and onto a second region downstream of the first region in a second direction perpendicular to both the optical axis and the first direction; a moving portion that moves the second optical portion relative to the support portion; an imaging portion that acquires an image of the modified region; and a control portion that controls the first optical portion such that it imparts laser light to each of a plurality of different astigmatisms, controls the moving portion such that it moves relative to the first region of the glass substrate along a second direction, and outputs the image of the modified region acquired by the imaging portion in association with each of the plurality of astigmatisms.

[0088] In this laser processing apparatus, laser light is sequentially applied to each of a plurality of distinct astigmatisms, and an image of a modified region formed on a glass substrate by the irradiation of the laser is output in association with each of the plurality of astigmatisms. Here, if a first region of a laser focused in a first direction is moved relative to the glass substrate along a second direction, the direction of cracks extending from the modified region tends to stabilize. Furthermore, if the direction of the cracks extending from the modified region is along the second direction, sufficient bending strength can be easily ensured for multiple chips obtained by cutting an object. Therefore, by applying laser light to astigmatisms associated with the image of a modified region where the crack direction is along the second direction, laser processing conditions that stably ensure sufficient bending strength can be achieved. Thus, this laser processing apparatus can ensure sufficient bending strength for multiple chips obtained by cutting an object including a glass substrate.

[0089] In one aspect of the laser processing apparatus disclosed herein, the first optical unit may be a spatial light modulator, and the control unit may input signals representing each of the plurality of astigmatic patterns corresponding to each of the plurality of astigmatisms into the spatial light modulator. This allows for the easy and reliable application of laser light to each of the plurality of dissimilar astigmatisms.

[0090] In one aspect of the laser processing apparatus of this disclosure, each of the plurality of astigmatic patterns may be an astigmatic pattern in which the value obtained by dividing the width of the first region in the second direction by the width of the first region in the first direction is different from each other. Thus, it is possible to easily and reliably impart laser light to each of the plurality of different astigmatic patterns.

[0091] In one aspect of the laser processing apparatus disclosed herein, the control unit may include a display unit that displays an image of the modified area acquired by the camera unit in association with each of a plurality of astigmatisms. This allows the operator to objectively identify the relationship between astigmatism and the modified area.

[0092] In one aspect of the laser processing apparatus disclosed herein, the control unit may include an input receiving unit that accepts an input of any one of a plurality of astigmatisms as laser processing conditions. This allows the operator to set an appropriate astigmatism as the laser processing condition.

[0093] One aspect of the laser processing method disclosed herein is a processing method for forming a modified region on a glass substrate by irradiating an object including a glass substrate with a laser, and includes: a first step of sequentially applying a laser to each of a plurality of different astigmatisms to acquire an image of the modified region, wherein the modified region is formed on the glass substrate by irradiation with a laser applied to each of the plurality of astigmatisms; and a second step of associating the image of the modified region with each of the plurality of astigmatisms, wherein in the first step, the laser applied to each of the plurality of astigmatisms is focused on a first region in a first direction perpendicular to the optical axis of the laser, and focused on a second region downstream of the first region in a second direction perpendicular to the optical axis and the first direction, and the first region is moved relative to the glass substrate along the second direction.

[0094] In this laser processing method, for the same reasons as the laser processing apparatus described above, by applying laser light with astigmatism associated with an image of a modified region where the crack direction is along a second direction, laser processing conditions that stably ensure sufficient bending strength can be achieved. Therefore, this laser processing method can ensure sufficient bending strength for multiple chips obtained by cutting an object including a glass substrate.

[0095] The laser processing method of this disclosure may also include: a third step, setting any one of a plurality of astigmatisms of an image associated with the modified region as a laser processing condition.

[0096] According to this disclosure, a laser processing apparatus and a laser processing method can be provided that can ensure sufficient bending strength for multiple chips obtained by cutting an object including a glass substrate.

Claims

1. A laser processing apparatus, wherein, It is a laser processing apparatus that forms a modified region on a glass substrate by irradiating the substrate with a laser. The laser processing apparatus includes: Support portion, which supports the object; A light source that emits the laser; A first optical section imparts astigmatism to the laser emitted from the light source; The second optical unit focuses the laser, which has been given astigmatism by the first optical unit, into a first region in a first direction perpendicular to the optical axis of the laser, and into a second region downstream of the first region in a second direction perpendicular to both the optical axis and the first direction. A moving part that causes the second optical part to move relative to the support part; The camera unit acquires images of the modified area; as well as The control unit controls the first optical unit in such a way that it imparts the laser with each of a plurality of different astigmatisms, controls the moving unit in such a way that it moves relative to the first region of the glass substrate along the second direction, and outputs the image of the modified region acquired by the imaging unit in association with each of the plurality of astigmatisms.

2. The laser processing apparatus according to claim 1, wherein, The first optical component is a spatial light modulator. The control unit inputs a signal representing each of the plurality of astigmatic patterns corresponding to each of the plurality of astigmatisms into the spatial light modulator.

3. The laser processing apparatus according to claim 2, wherein, Each of the plurality of astigmatic patterns is an astigmatic pattern in which the width of the first region in the second direction is divided by the width of the first region in the first direction, and the resulting values ​​are all different.

4. The laser processing apparatus according to any one of claims 1 to 3, wherein, The control unit includes a display unit that displays the image of the modified region acquired by the camera unit in association with each of the plurality of astigmatisms.

5. The laser processing apparatus according to any one of claims 1 to 4, wherein, The control unit includes an input receiving unit that accepts the input of any one of the plurality of astigmatisms as laser processing conditions.

6. A laser processing method, wherein, This is a processing method that forms a modified region on a glass substrate by irradiating the object, including the glass substrate, with a laser. The laser processing method comprises: The first step involves sequentially applying the laser to each of a plurality of different astigmatisms to obtain an image of the modified region, which is formed on the glass substrate by irradiation with the lasers applied to each of the plurality of astigmatisms. as well as The second step is to associate the image of the modified region with each of the plurality of astigmatisms. In the first step, the lasers, each of the plurality of astigmatisms, are focused in a first direction perpendicular to the optical axis of the laser into a first region, and in a second direction perpendicular to both the optical axis and the first direction into a second region downstream of the first region in the direction of travel of the laser, and the first region is moved relative to the glass substrate along the second direction.

7. The laser processing method according to claim 6, wherein, It also includes: a third step, setting any one of the plurality of astigmatisms of the image associated with the modified region as a laser processing condition.

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