KR20230004260A - Laser processing apparatus and laser processing method - Google Patents

Abstract

Provided is a laser processing device, which comprises: a support part which supports a target material including a glass substrate; a light source which emits laser light; a first optical part which provides astigmatism to the laser light; a second optical part which focuses the laser light in a first area perpendicular to the optical axis of the laser light in a first direction, and focuses the laser light in a second area downstream of the first area in a second direction perpendicular to both the optical axis and the first direction; a moving part which relatively moves the second optical part with respect to the support part; an imaging part which captures an image of a modified area; and a control part which controls the first optical part to provide each of a plurality of astigmatisms to the laser light, controls the moving part to relatively move the first area in the second direction on the glass substrate, and outputs the image of the modified area in association with each of the plurality of astigmatisms. The laser machining apparatus ensures sufficient bending strength for a plurality of chips obtained by cutting a target material.

Description

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

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

A laser processing apparatus that forms a modified region on an object by irradiating the object with a laser beam is known (eg, see Japanese Laid-Open Patent Publication No. 2011-051011). Such a laser processing apparatus includes a support part for supporting an object, a light source for emitting laser light, a spatial light modulator for modulating the laser light emitted from the light source, and a condensing unit for condensing the laser light modulated by the spatial light modulator. There are cases where it is available.

In the laser processing apparatus as described above, a modified region may be formed along each of a plurality of lines in the glass substrate by irradiating a laser beam along each of a plurality of lines to an object including a glass substrate. In such a case, it is important that sufficient transverse strength is secured for a plurality of chips obtained by cutting an object including a glass substrate along each of a plurality of lines. However, in some laser processing devices, even under laser processing conditions that can ensure sufficient bending strength, if the laser processing conditions are applied to other laser processing devices having the same specifications as the laser processing device, there are cases where sufficient bending strength is not secured. there is.

An object of the present disclosure is to provide a laser processing apparatus and a laser processing method capable of securing sufficient transverse bending strength for a plurality of chips obtained by cutting an object including a glass substrate.

A laser processing apparatus according to one aspect of the present disclosure is a laser processing apparatus for forming a modified region on a glass substrate by irradiating a laser beam on an object including a glass substrate, comprising: a support unit for supporting the object; a light source for emitting laser light; and , a first optical unit for imparting astigmatism to the laser light emitted from the light source, and condensing the laser light to which astigmatism is imparted by the first optical unit to a first area in a first direction perpendicular to the optical axis of the laser light; , In the second direction perpendicular to the optical axis and the first direction, the second optical unit for condensing light in the second area on the downstream side of the first area in the traveling direction of the laser light, and movement for relatively moving the second optical unit with respect to the support unit. A first optical unit is controlled so that a plurality of astigmatisms different from each other as astigmatism are imparted to the laser beam, and the first area in the glass substrate is relative along the second direction. and a control unit which controls the movement unit to move to , and outputs the image of the modified region acquired by the imaging unit in association with each of a plurality of astigmatisms.

A laser processing method of one aspect of the present disclosure is a laser processing method of forming a modified region on a glass substrate by irradiating laser light onto an object including a glass substrate, and sequentially applying a plurality of different astigmatisms to the laser light. and a first step of acquiring an image of a modified region formed on the glass substrate by irradiation of a laser beam to which each of a plurality of astigmatisms has been applied, and a second step of associating the image of the modified region with each of a plurality of astigmatisms. , In the first step, the laser light to which each of the plurality of astigmatisms has been applied is condensed in the first area in the first direction perpendicular to the optical axis of the laser light, and the laser light travels in the second direction perpendicular to the optical axis and the first direction. and condensing light on a second area on the downstream side of the first area in the direction, and relatively moving the first area along the second direction in the glass substrate.

1 is a configuration diagram of a laser processing apparatus according to an embodiment.
FIG. 2 is a cross-sectional view of a part of the spatial light modulator shown in FIG. 1 .
3 is a plan view of a glass substrate as an object of one embodiment.
Fig. 4 is a diagram showing an astigmatism pattern displayed on the spatial light modulator shown in Fig. 1;
FIG. 5 is a diagram showing an optical path of a laser light to which astigmatism is imparted by the spatial light modulator shown in FIG. 1 .
FIG. 6 is a diagram showing the shape of a first region of laser light to which astigmatism is imparted by the spatial light modulator shown in FIG. 1;
Fig. 7 is a diagram showing a display state and an input reception state of the interface unit shown in Fig. 1;
8 is a diagram showing an image of a modified region formed on a glass substrate.
9 is a diagram showing transverse strength of a plurality of chips obtained by cutting a glass substrate.
Fig. 10 is a diagram showing the relationship between astigmatism for each condensing lens unit and an image of a modified region.
Fig. 11 is a diagram showing the relationship between astigmatism for each laser processing device and an image of a modified region.
Fig. 12 is a diagram showing the relationship between astigmatism for each glass material and an image of a modified region.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this indication is described in detail with reference to drawings. In each drawing, the same reference numerals are assigned to the same or equivalent parts, and overlapping descriptions are omitted.

[Configuration of laser processing equipment]

As shown in FIG. 1 , 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, and a light collecting 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 are provided. A laser processing device 1 is a device that forms a modified region 12 in an object 11 by irradiating the object 11 with a laser beam L. In the following description, three mutually orthogonal directions are referred to as the X direction, Y direction, and Z direction, respectively. 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.

The support part 2 supports the target object 11 . As an example, the support unit 2 supports the object 11 so that the surface 11a of the object 11 is orthogonal to the Z direction by adsorbing a film (not shown) bonded to the object 11 . The support part 2 is movable along each direction of the X direction and the Y direction, and is rotatable about the axis parallel to the Z direction as a center line.

The light source 3 emits a laser beam L. As an example, the light source 3 emits the laser light L by the pulse oscillation method. The laser light L has transparency to the target object 11 .

The optical axis adjustment unit 4 adjusts the optical axis of the laser beam L emitted from the light source 3 . In this embodiment, the optical axis adjustment unit 4 adjusts the optical axis of the laser beam L while changing the traveling direction of the laser beam L emitted from the light source 3 so as to follow the Z direction. The optical axis adjustment unit 4 is constituted by, for example, a plurality of reflection mirrors whose positions and angles can be adjusted.

The spatial light modulator 5 is disposed within the case H. The spatial light modulator 5 modulates the laser light L emitted from the light source 3 . In this embodiment, the laser beam L, which has traveled downward along the Z direction from the optical axis adjustment unit 4, is incident into the case H, and the laser beam L, which has entered the case H, is incident on the mirror M1. The laser light L reflected by the mirror M1 is incident on the spatial light modulator 5, and is reflected horizontally at an angle with respect to the Y direction. The spatial light modulator 5 modulates the incident laser light L while reflecting it horizontally along the Y direction.

The light collecting part 6 is attached to the bottom wall of the case H. The condensing unit 6 condenses the laser light L modulated by the spatial light modulator 5 onto the object 11 supported by the support unit 2 . In this embodiment, the laser light L reflected horizontally along the Y direction by the spatial light modulator 5 is reflected downward along the Z direction by the dichroic mirror M2, and the dichroic mirror ( The laser light L reflected by M2 is incident on the condensing part 6. The condenser 6 condenses the incident laser light L along the Z direction from the surface 11a side to the target object 11 . In this embodiment, the condensing unit 6 is configured by attaching the condensing lens unit 61 to the bottom wall of the case H via the driving mechanism 62 . The condensing lens unit 61 has a function of condensing parallel light to one point on the optical axis. The driving mechanism 62 moves the condensing lens unit 61 along the Z direction by, for example, a driving force of a piezoelectric element.

Further, in the case H, between the spatial light modulator 5 and the condensing unit 6, an imaging optical system (not shown) is disposed. The imaging optical system constitutes a bilateral telecentric optical system in which the reflective surface of the spatial light modulator 5 and the entrance pupil surface of the condenser 6 are in an image forming relationship. As a result, the image of the laser light L on the reflection surface of the spatial light modulator 5 (the image of the laser light L modulated by the spatial light modulator 5) is the incident concentric plane of the condenser 6. It is analogous to (phase 似) and is inverted (phased).

A pair of range sensors S1 and S2 are mounted on the bottom wall of the case H so as to be positioned on both sides of the condensing lens unit 61 in the X direction. Each of the ranging sensors S1 and S2 emits light for ranging (e.g., laser light) to the surface 11a of the target object 11, and detects the light for ranging reflected from the surface 11a. By doing so, displacement data of the surface 11a is acquired.

The moving unit 7 relatively moves the light collecting unit 6 with respect to the support unit 2 . The moving unit 7 moves at least one of the case H and the support unit 2, thereby moving the light collecting unit 6 relative to the support unit 2. A moving mechanism (including a drive source such as an actuator or a motor) is). In this embodiment, the moving part 7 moves the support part 2 along each direction of the X direction and the Y direction, rotates the support part 2 with the axis parallel to the Z direction as a center line, and the Z direction Move the case (H) along.

The visible imaging unit 8 is disposed within the case H. The visible imaging unit 8 emits visible light (V) and acquires an image of the target object 11 by the visible light (V) as an image. In this embodiment, visible light V emitted from the visible imaging unit 8 is irradiated to the surface 11a of the object 11 via the dichroic mirror M2 and the light collecting unit 6, and the surface 11a The visible light V reflected from ) is detected by the visible image pickup unit 8 via the light collecting unit 6 and the dichroic mirror M2.

The infrared imaging unit 9 is attached to the side wall of the case H. The infrared imaging unit 9 emits infrared light and acquires an image of the target object 11 by the infrared light as an image. In this embodiment, the case H and the infrared imaging unit 9 are integrally movable along the Z direction.

The control unit 10 controls the operation of each unit of the laser processing apparatus 1 . The control unit 10 has a processing unit 101, a storage unit 102, and an interface unit (display unit, input reception unit) 103. The processing unit 101 is configured as a computer device including a processor, memory, storage, communication device, and the like. In the processing unit 101, a processor executes software (programs) read into a memory or the like, and controls reading and writing of data in the memory and storage, and communication by the communication device. The storage unit 102 is, for example, a hard disk or the like, and stores various types of data. The interface unit 103 displays various data to the operator or accepts input of various data from the operator. In the present embodiment, the interface unit 103 constitutes a graphical user interface (GUI).

In the laser processing apparatus 1 configured as described above, when the laser beam L is condensed inside the target object 11, the laser beam L is emitted at the portion corresponding to the convergence point C of the laser beam L. It is absorbed, and a modified region 12 is formed inside the object 11 . The modified region 12 is a region that differs in density, refractive index, mechanical strength, and other physical properties from surrounding unmodified regions. Examples of the modified region 12 include a melted region, a crack region, a dielectric breakdown region, and a refractive index change region. The modified region 12 has a characteristic that cracks tend to extend from the modified region 12 to the incident side of the laser beam L and to the opposite side. This characteristic of the modified region 12 is used for cutting the object 11 .

As an example, the operation of the laser processing apparatus 1 in the case of forming the modified region 12 inside the object 11 along the line 15 for cutting the object 11 will be described.

First, the laser processing apparatus 1 rotates the support part 2 with the axis parallel to the Z direction as the center line so that the line 15 set on the object 11 is parallel to the X direction. Then, based on the image acquired by the infrared imaging unit 9 (for example, the image of the functional element layer of the target object 11), the laser processing device 1 generates laser light when viewed from the Z direction. The support part 2 is moved along each direction of the X direction and the Y direction so that the light converging point C of (L) may be located on the line 15.

Next, the laser processing device 1 determines the convergence point of the laser beam L based on the image acquired by the visible imaging unit 8 (for example, the image of the surface 11a of the object 11). (C) is moved along the Z direction so that the case H (i.e., the light concentrating portion 6) is positioned on the surface 11a. Next, the laser processing apparatus 1 is positioned along the Z direction so that the light converging point C of the laser beam L is located at a predetermined depth from the surface 11a with the position as a reference, the case H (that is, The light collecting part 6 is moved.

Next, the laser processing apparatus 1 emits the laser light L from the light source 3, and the light converging point C of the laser light L moves relatively along the line 15, X Move the support 2 along the direction. At this time, the laser processing apparatus 1 measures the distance that is located on the front side (the front side in the relative moving direction of the laser beam L with respect to the target object 11) of the pair of range sensors S1 and S2. Based on the displacement data of the surface 11a acquired by the sensor, the drive mechanism 62 of the light condensing part 6 so that the light converging point C of the laser light L is located at a predetermined depth from the surface 11a. to operate

As a result of the above, a row of modified regions 12 are formed along the line 15 and at a certain depth from the surface 11a of the object 11 . When the laser light L is emitted from the light source 3 by the pulse oscillation method, a plurality of modified spots 12s are formed so as to line up in a row along the X direction. One modified spot 12s is formed by irradiation of one pulse of laser light L. The row of modified regions 12 is a set of a plurality of modified spots 12s arranged in a row. The modified spots 12s adjacent to each other are determined by the pulse pitch of the laser light L (a value obtained by dividing the relative movement speed of the light converging point C with respect to the object 11 by the repetition frequency of the laser light L), Sometimes they are connected to each other, sometimes they are separated from each other.

[Configuration of Spatial Light Modulator]

The spatial light modulator 5 of the present embodiment is a spatial light modulator (SLM: Spatial Light Modulator) of a reflective liquid crystal (LCOS: Liquid, Crystal, On Silicon). As shown in FIG. 2 , the spatial light modulator 5 includes a driving circuit layer 52, a pixel electrode layer 53, a reflective film 54, an alignment film 55, and a liquid crystal layer 56 on a semiconductor substrate 51. , the alignment film 57, the transparent conductive film 58 and the transparent substrate 59 are laminated in this order.

The semiconductor substrate 51 is, for example, a silicon substrate. The driving circuit layer 52 constitutes 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 shape along the surface of the semiconductor substrate 51 . Each pixel electrode 53a is formed of, for example, a metal material such as aluminum. A voltage is applied to each pixel electrode 53a by the driving circuit layer 52 .

The reflective film 54 is, for example, a dielectric multilayer film. The alignment film 55 is provided on the surface of the liquid crystal layer 56 on the reflective film 54 side, and the alignment film 57 is provided on the surface of the liquid crystal layer 56 on the opposite side to the reflective film 54 . Each of the alignment films 55 and 57 is formed of, for example, a polymer material such as polyimide, and the contact surface of each alignment film 55 and 57 with the liquid crystal layer 56 is rubbed, for example. is being carried out. The alignment films 55 and 57 align the liquid crystal molecules 56a included in the liquid crystal layer 56 in a certain direction.

The transparent conductive film 58 is provided on the surface of the transparent substrate 59 on the alignment film 57 side, and faces the pixel electrode layer 53 with the liquid crystal layer 56 or the like interposed therebetween. 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 transmit the laser light L.

In the spatial light modulator 5 configured as described above, when a signal indicating a modulation pattern is input from the control unit 10 to the driving circuit layer 52, a voltage corresponding to the signal is applied to each pixel electrode 53a, and each An electric field is formed between the pixel electrode 53a and the transparent conductive film 58 . When the electric field is formed, the arrangement direction of the liquid crystal molecules 216a changes for each region corresponding to each pixel electrode 53a in the liquid crystal layer 56, and the refractive index for each region corresponding to each pixel electrode 53a changes. It changes. This state is a state in which the modulation pattern is displayed on the liquid crystal layer 56 .

With the modulation pattern displayed on the liquid crystal layer 56, the laser light L is incident on the liquid crystal layer 56 from the outside via the transparent substrate 59 and the transparent conductive film 58, and When reflected and emitted to the outside via the transparent conductive film 58 and the transparent substrate 59 from the liquid crystal layer 56, the laser light L is modulated according to the modulation pattern displayed on the liquid crystal layer 56. In this way, according to the spatial light modulator 5, by appropriately setting the modulation pattern displayed on the liquid crystal layer 56, the laser light L is modulated (for example, the intensity, amplitude, and phase of the laser light L). , modulation of polarization, etc.) is possible.

[Construction of object]

The target object 11 of this embodiment is the glass substrate 20 as shown in FIG. As an example, the glass substrate 20 is formed in a rectangular plate shape by synthetic quartz glass, non-alkali glass, borosilicate glass or the like. In addition, in addition to the glass substrate 20, the object 11 of this embodiment further includes another layer (for example, a film formed on at least one main surface of the glass substrate 20, etc.) Okay.

The glass substrate 20 is irradiated with the laser beam L along each of the plurality of lines 15 . As a result, the modified region 12 is formed in the glass substrate 20 along each of the plurality of lines 15 . In this embodiment, the modified region 12 is formed on the glass substrate 20 so that the entirety of the modified region 12 is located inside the glass substrate 20 . Further, the modified region 12 may be formed on the glass substrate 20 so that a part of the modified region 12 is exposed to the outside.

In the glass substrate 20 on which the modified region 12 is formed, cracks extend from the modified region 12 to the incident side of the laser beam L and to the opposite side to form a plurality of chips along the plurality of lines 15 respectively. is cut In this embodiment, the plurality of lines 15 are set in a grid pattern when viewed from the thickness direction of the glass substrate 20 . Each line 15 is a virtual line set on the glass substrate 20 by the laser processing apparatus 1 . In addition, each line 15 may be a line actually drawn on the glass substrate 20 .

[Functions of Control Unit]

The controller 10 inputs a signal representing the astigmatism pattern AS to the spatial light modulator 5 as shown in FIG. 4 . As a result, the astigmatism pattern AS is displayed on the liquid crystal layer 56 of the spatial light modulator 5, and astigmatism is imparted to the laser light L incident on the condenser 6. In this embodiment, the laser light L is oscillated from the light source 3 by a burst pulse of an ultra-short pulse laser.

When the laser light L, to which astigmatism is imparted by the spatial light modulator 5, enters the condensing unit 6, as shown in FIG. In the Y direction (the first direction perpendicular to the optical axis of the laser light L), the light is focused on the first region R1, and in the X direction (the second direction perpendicular to the optical axis and the first direction of the laser light L) The light is focused on the second region R2. The second region R2 is located on the downstream side of the first region R1 in the traveling direction of the laser beam L. Also, in FIG. 5 , illustration of an optical component disposed between the spatial light modulator 5 and the condensing unit 6 is omitted.

In this state, the control part 10 controls the moving part 7 so that the 1st area|region R1 of the glass substrate 20 may relatively move along the X direction. As a result, the modified region 12 is formed in the glass substrate 20 along the X direction. Next, 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 .

On the premise of 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 for determining laser processing conditions for forming modified regions 12 suitable for cutting the glass substrate 20 into a plurality of chips. In addition, the laser processing method performed in the laser processing condition determination mode corresponds to the laser processing method of the present embodiment.

First, the controller 10 controls the spatial light modulator 5 so that each of a plurality of different astigmatisms is sequentially applied to the laser light L, and the laser light L to which each of the plurality of astigmatisms is applied The visible imaging unit 8 is controlled so that an image of the modified region 12 formed on the glass substrate 20 by irradiation is acquired (first step). In each state in which a plurality of astigmatisms are applied to the laser light L, the control unit 10 moves the moving unit 7 so that the first region R1 on the glass substrate 20 moves relatively along the X direction. ) to control. As a result, a modified region 12 corresponding to astigmatism is formed on the glass substrate 20 .

In the first step, the controller 10 inputs a signal indicating each of a plurality of astigmatism patterns AS corresponding to each of a plurality of astigmatism to the spatial light modulator 5 . As shown in FIG. 6 , each of the plurality of astigmatism patterns AS sets the width of the first region R1 in the X direction (left-right direction in FIG. 6) to the first area in the Y-direction (vertical direction in FIG. 6). It is an astigmatism pattern in which the value divided by the width of the region R1 (hereinafter referred to as "ellipticity") is different. When the ellipticity of the first region R1 is 1, when the astigmatism pattern AS is not input to the spatial light modulator 5, that is, when astigmatism is not applied to the laser light L to be. In FIG. 6 , the diameter of the first region R1 when the ellipticity is 1 is, for example, about 1 μm. The shape of the first region R1 of the laser light L to which astigmatism is applied is not limited to a perfect elliptical shape, and may be, for example, a flat circular shape or an oval shape.

After the first step, the control unit 10 associates (in other words, associates) the image of the modified region 12 acquired by the visible imaging unit 8 with each of a plurality of astigmatisms (second step) , After the second step, the controller 10 sets one of a plurality of astigmatism associated with the image of the modified region 12 as the laser processing condition (third step). In this embodiment, as shown in FIG. 7 , the interface unit 103 is an image of the modified region 12 acquired by the visible imaging unit 8 (when viewed from the thickness direction of the glass substrate 20). The image of the modified region 12) is displayed in association with each of a plurality of astigmatisms (ellipticity in FIG. 7), and any one of the plurality of astigmatisms (ellipticity in FIG. 7) is input as a laser processing condition.

In the example shown in FIG. 7 , the larger the ellipticity of the first region R1 (in other words, the stronger the astigmatism applied to the laser beam L), the direction of the crack extending from the modified region 12 is X. A trend along the direction (left-right direction in Fig. 7) is shown. In the example shown in FIG. 7 , black dotted regions correspond to modified spots, and black linear regions extending from the modified spots correspond to cracks. If the direction of the crack extending from the modified region 12 is along the X direction (that is, if the direction of the crack is along the direction in which the line 15 extends), a plurality of chips obtained by cutting the glass substrate 20 It is easy to ensure sufficient transverse bending strength for From this, the operator selects an image of the modified region 12 in which the crack direction is along the X direction, and inputs the astigmatism (ellipticity in FIG. 7) associated with the image to the control unit 10 as laser processing conditions. . In addition, the transverse strength is the fracture stress (stress when the chip is broken) obtained by the transverse strength measurement test. In the transverse strength measurement test, a chip is placed on two first cylinders arranged in parallel, and in that state, two second cylinders arranged in parallel at a smaller interval than the two first cylinders are used to lower the chip. This is a test (four-point bending test) in which an external force is applied and the stress when the chip is destroyed is measured.

[action and effect]

In the laser processing device 1 and the laser processing method performed in the laser processing device 1, each of a plurality of different astigmatisms is sequentially applied to the laser light L, and the irradiation of the laser light L An image of the modified region 12 formed on the glass substrate 20 is output in association with each of a plurality of astigmatisms. Here, when the first region R1 of the laser beam L condensed in the Y direction is relatively moved along the X direction in the glass substrate 20, the direction of the crack extending from the modified region 12 is stabilized. tend to become In addition, when the direction of the crack extending from the modified region 12 is along the X direction, sufficient transverse bending strength is easily secured for a plurality of chips obtained by cutting the glass substrate 20 . Therefore, by giving the laser beam L an astigmatism associated with the image of the modified region 12 in which the direction of the crack is in the X direction, it is possible to realize laser processing conditions under which sufficient transverse bending strength can be secured stably. . Therefore, the laser processing apparatus 1 and the laser processing method performed by the laser processing apparatus 1 make it possible to secure sufficient transverse bending strength for a plurality of chips obtained by cutting the glass substrate 20 . In addition, outputting the image of the modified region 12 in association with each of a plurality of astigmatisms is not limited to displaying them on the interface unit 103, but also includes storing them in a storage device such as a memory.

In the laser processing apparatus 1, the control unit 10 inputs a signal indicating each of a plurality of astigmatism patterns AS corresponding to each of a plurality of astigmatism to the spatial light modulator 5. Thereby, each of a plurality of different astigmatisms can be easily and reliably imparted to the laser light L.

In the laser processing apparatus 1, each of the plurality of astigmatism patterns AS has a value obtained by dividing the width of the first region R1 in the X direction by the width of the first region R1 in the Y direction differently from each other. is an astigmatism pattern that Thereby, each of a plurality of different astigmatisms can be easily and reliably imparted to the laser light L.

In the laser processing apparatus 1, the control unit 10 has an interface unit 103 for displaying the image of the modified region 12 acquired by the visible imaging unit 8 in association with each of a plurality of astigmatisms . This allows the operator to objectively recognize the relationship between astigmatism and the modified region 12 .

In the laser processing apparatus 1, the control unit 10 has an interface unit 103 that accepts an input of any one of a plurality of astigmatism as laser processing conditions. This allows the operator to set appropriate astigmatism as laser processing conditions.

[Experiment result]

8(a) is an image of a modified region formed on a 500 μm-thick glass substrate made of alkali-free glass by irradiation of a laser beam to which no astigmatism is applied (when viewed from the thickness direction of the glass substrate). image of the modified region). 8(b) is an image of a modified region formed on a 500 μm-thick glass substrate made of alkali-free glass by irradiation of a laser beam with astigmatism having an ellipticity of 1.61 (when viewed from the thickness direction of the glass substrate). image of the modified region of ). In Fig. 8(a) and Fig. 8(b), the laser processing conditions were the same as follows except for whether or not astigmatism was applied to the laser light. From the results of Fig. 8 (a) and (b), the laser beam to which astigmatism is applied is condensed in the first area in the Y direction (vertical direction in FIG. 8), and the first area is formed on the glass substrate in the X direction ( It was found that the direction of the crack extending from the modified region is stabilized in the state along the X direction when relatively moved along the left-right direction in FIG. 8). In addition, the laser processing conditions are as follows.

Wavelength of laser light: 1028 nm

Laser light pulse width: 300 fs

The repetition frequency of the laser beam: 50 kHz

Relative movement speed of laser light to glass substrate: 500 mm/s

Laser light energy: 2 μJ

Distance from the laser beam incident surface of the glass substrate to the modified region: 80 μm

Fig. 9(a) is a diagram showing the transverse bending strength of a plurality of chips obtained when a modified region is formed on a glass substrate made of fluorophosphate glass and having a thickness of 200 µm by irradiation with laser light to which no astigmatism is applied. to be. Fig. 9(b) shows the transverse bending strength of a plurality of chips obtained when a modified region is formed on a 200 µm-thick glass substrate made of fluorophosphate glass by irradiation with a laser beam having astigmatism of ellipticity of 1.61. it is a drawing In Fig. 9(a) and Fig. 9(b), except for whether or not astigmatism is applied to the laser beam, the laser processing conditions are the same as follows, and the chip size when viewed in the thickness direction is also It was made the same as 5 mm x 7 mm. In Fig. 9 (a) and (b), "push the incident surface" indicates that a load is applied to the chip from the surface (incident surface) side of the chip on the side where the laser beam is incident, and "press the back surface", Indicates that a load is applied to the chip from the back side of the chip (the surface opposite to the incident surface). From the results of Fig. 9 (a) and (b), when the modified region is formed in the glass substrate by irradiation of a laser beam to which no astigmatism is applied, the fracture stress representing the transverse strength is non-uniform. It was found that when a modified region was formed in a glass substrate by irradiation with a laser beam having a graded difference, the fracture stress representing the transverse strength was stabilized at a high value. In addition, the laser processing conditions are as follows.

Wavelength of laser light: 1028 nm

Laser light pulse width: 300 fs

The repetition frequency of the laser beam: 50 kHz

Relative moving speed of laser light to glass substrate: 400 mm/s

Laser light energy: 7 μJ

Distance from the laser light incident surface of the glass substrate to the modified region: 100 μm

10 is a diagram showing the relationship between astigmatism for each condensing lens unit and the image of the modified region (the image of the modified region when viewed from the thickness direction of the glass substrate). From the result of FIG. 10 , in the modified region formed on the glass substrate by irradiation of a laser beam to which no astigmatism is applied (irradiation of a laser beam having an ellipticity of 1), the directions of cracks extending from the modified region are not uniform due to the condensing lens unit. On the other hand, for the modified region formed on the glass substrate by irradiation of laser light to which astigmatism with an ellipticity of 1.03 to 1.08 is imparted, as the ellipticity approaches 1.08, the direction of the crack extending from the modified region is in the X direction (FIG. 10). was found to be stable in the state along the left-right direction).

Fig. 11 is a diagram showing the relationship between astigmatism for each laser processing device and an image of a modified region (an image of a modified region when viewed from the thickness direction of a glass substrate). From the results of FIG. 11 , in the modified region formed on the glass substrate by irradiation of laser light to which astigmatism is not applied (irradiation of laser light having an ellipticity of 1), the directions of cracks extending from the modified region are non-uniform by the laser processing device. On the other hand, for a modified region formed on a glass substrate by irradiation of a laser beam to which astigmatism with an ellipticity of 1.08 to 1.6 is imparted, the closer the ellipticity is to 1.6, the direction of the crack extending from the modified region is in the X direction (FIG. 11). was found to be stable in the state along the left-right direction).

12 is a diagram showing the relationship between astigmatism for each glass material and a modified region image (a modified region image when viewed from the thickness direction of the glass substrate). From the results in FIG. 12 , it is clear that for the modified region formed on the glass substrate by irradiation of laser light to which no astigmatism is applied (irradiation of laser light having an ellipticity of 1), the directions of cracks extending from the modified region are non-uniform in any glass material. On the other hand, for a modified region formed on a glass substrate by irradiation of a laser beam with astigmatism having an ellipticity of 1.04 to 1.6, as the ellipticity approaches 1.6, the direction of cracks extending from the modified region is in the X direction (in FIG. 12 direction) was found to be stable.

[modified example]

This indication is not limited to the said embodiment. For example, the first optical unit for imparting astigmatism to the laser light L emitted from the light source 3 is not limited to the spatial light modulator 5 . As an example, the first optical unit may be an optical system including a cylindrical lens movable along the optical axis direction. However, only the cross-sectional shape of the laser beam L perpendicular to the optical axis was made long in the condensing area by displaying a slit pattern on the spatial light modulator 5 or arranging a mechanical slit. With this, it is difficult to stabilize the direction of cracks extending from the modified region 12.

The display unit for displaying the image of the modified region 12 in association with each of a plurality of astigmatisms is not limited to the interface unit 103, and may be a display or the like provided separately from the control unit 10. An input accepting unit that accepts an input of any of a plurality of astigmatisms as a laser processing condition is not limited to the interface unit 103, and may be a mouse, keyboard, or the like provided separately from the control unit 10.

In the above embodiment, the X direction is the first horizontal direction, the Y direction is the second horizontal direction perpendicular to the first horizontal direction, and the Z direction is the vertical direction. direction is not limited. For example, the Z direction may be a direction crossing the vertical direction.

A laser processing apparatus according to one aspect of the present disclosure is a laser processing apparatus for forming a modified region on a glass substrate by irradiating a laser beam on an object including a glass substrate, comprising: a support unit for supporting the object; a light source for emitting laser light; and , a first optical unit for imparting astigmatism to the laser light emitted from the light source, and condensing the laser light to which astigmatism is imparted by the first optical unit to a first area in a first direction perpendicular to the optical axis of the laser light; , In the second direction perpendicular to the optical axis and the first direction, the second optical unit for condensing light in the second area on the downstream side of the first area in the traveling direction of the laser light, and movement for relatively moving the second optical unit with respect to the support unit. A first optical unit is controlled so that a plurality of astigmatisms different from each other as astigmatism are imparted to the laser beam, and the first area in the glass substrate is relative along the second direction. and a control unit which controls the movement unit to move to , and outputs the image of the modified region acquired by the imaging unit in association with each of a plurality of astigmatisms.

In this laser processing apparatus, each of a plurality of different astigmatisms is sequentially applied to a laser beam, and an image of a modified region formed on a glass substrate by irradiation of the laser beam is output in association with each of the plurality of astigmatisms. Here, when the first region of the laser beam focused in the first direction is relatively moved along the second direction in the glass substrate, the direction of the crack extending from the modified region tends to be stabilized. In addition, when the direction of the crack extending from the modified region is in the second direction, sufficient transverse strength is easily secured for a plurality of chips obtained by cutting the object. Therefore, by imparting astigmatism associated with the image of the modified region along the second direction to the laser beam, it is possible to realize laser processing conditions in which sufficient transverse bending strength can be secured stably. Therefore, this laser processing apparatus makes it possible to secure sufficient bending strength for a plurality of chips obtained by cutting an object including a glass substrate.

In the laser processing apparatus of one aspect of the present disclosure, the first optical unit is a spatial light modulator, and the control unit may input a signal representing each of a plurality of astigmatism patterns corresponding to each of a plurality of astigmatisms to the spatial light modulator. Thereby, each of a plurality of mutually different astigmatisms can be easily and reliably imparted to the laser light.

In the laser processing apparatus of one aspect of the present disclosure, each of the plurality of astigmatism patterns has a different 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. even is fine Thereby, each of a plurality of mutually different astigmatisms can be easily and reliably imparted to the laser light.

In the laser processing apparatus of one aspect of the present disclosure, the control unit may have a display unit that displays the image of the modified region acquired by the imaging unit in association with each of a plurality of astigmatisms. This allows the operator to objectively recognize the relationship between astigmatism and the modified region.

In the laser processing apparatus of one aspect of the present disclosure, the control unit may have an input acceptance unit that accepts an input of any one of a plurality of astigmatism as laser processing conditions. This allows the operator to set appropriate astigmatism as laser processing conditions.

A laser processing method of one aspect of the present disclosure is a laser processing method of forming a modified region on a glass substrate by irradiating laser light onto an object including a glass substrate, and sequentially applying a plurality of different astigmatisms to the laser light. and a first step of acquiring an image of a modified region formed on the glass substrate by irradiation of a laser beam to which each of a plurality of astigmatisms has been applied, and a second step of associating the image of the modified region with each of a plurality of astigmatisms. , In the first step, the laser light to which each of the plurality of astigmatisms has been applied is condensed in the first area in the first direction perpendicular to the optical axis of the laser light, and the laser light travels in the second direction perpendicular to the optical axis and the first direction. and condensing light on a second area on the downstream side of the first area in the direction, and relatively moving the first area along the second direction in the glass substrate.

In this laser processing method, for the same reason as the above laser processing apparatus, by imparting to the laser light astigmatism associated with the image of the modified region in which the crack direction is in the second direction, sufficient transverse bending strength can be stably secured. possible laser processing conditions can be realized. Therefore, this laser processing method makes it possible to secure sufficient bending strength for a plurality of chips obtained by cutting an object including a glass substrate.

The laser processing method of one aspect of the present disclosure may further include a third step of setting any one of a plurality of astigmatism associated with the modified region image as a laser processing condition.

According to the present disclosure, it is possible to provide a laser processing apparatus and a laser processing method capable of securing sufficient transverse bending strength for a plurality of chips obtained by cutting an object including a glass substrate.

Claims (7)

A laser processing apparatus for forming a modified region in a glass substrate by irradiating a laser beam to an object including the glass substrate,
a support for supporting the object;
a light source for emitting the laser light;
a first optical unit for imparting astigmatism to the laser light emitted from the light source;
The laser light to which the astigmatism is imparted by the first optical unit is condensed in a first area in a first direction perpendicular to the optical axis of the laser light, and in a second direction perpendicular to the optical axis and the first direction. a second optical unit condensing light into a second area on the downstream side of the first area in the traveling direction of the laser light;
A moving unit for relatively moving the second optical unit with respect to the support unit;
an imaging unit that acquires an image of the modified region;
Controlling the first optical unit so that each of a plurality of different astigmatisms is applied to the laser light as the astigmatism, and controlling the moving unit so that the first area on the glass substrate moves relatively along the second direction; , a control unit for outputting the image of the modified region obtained by the imaging unit in association with each of the plurality of astigmatisms. The method of claim 1,
The first optical unit is a spatial light modulator,
wherein the control unit inputs a signal indicating each of a plurality of astigmatism patterns corresponding to each of the plurality of astigmatism to the spatial light modulator. The method of claim 2,
Wherein each of the plurality of astigmatism patterns is an astigmatism pattern in which a value obtained by dividing a width of the first region in the second direction by a width of the first region in the first direction is different from each other. According to any one of claims 1 to 3,
The control unit has a display unit for displaying the image of the modified region acquired by the imaging unit in association with each of the plurality of astigmatisms. According to any one of claims 1 to 4,
The laser processing apparatus wherein the control unit has an input acceptance unit that accepts an input of any one of the plurality of astigmatism as a laser processing condition. A laser processing method for forming a modified region in a glass substrate by irradiating a laser beam to an object including the glass substrate,
A first step of sequentially imparting a plurality of different astigmatisms to the laser light and acquiring an image of the modified region formed on the glass substrate by irradiation of the laser light to which each of the plurality of astigmatisms has been applied;
a second step of associating the image of the modified region with each of the plurality of astigmatism;
In the first step, the laser light to which each of the plurality of astigmatisms is applied is condensed in a first area in a first direction perpendicular to the optical axis of the laser light, and a second area perpendicular to the optical axis and the first direction is focused. direction, condensing the light in a second area on the downstream side of the first area in the traveling direction of the laser light, and relatively moving the first area along the second direction in the glass substrate. The method of claim 6,
and a third step of setting as a laser processing condition any one of the plurality of astigmatism associated with the image of the modified region.

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