WO2012063348A1

WO2012063348A1 - Laser processing method and device

Info

Publication number: WO2012063348A1
Application number: PCT/JP2010/070130
Authority: WO
Inventors: 望月　学; 浩義廣田; 能一坂口
Original assignee: パイオニア株式会社; 株式会社パイオニアＦａ
Priority date: 2010-11-11
Filing date: 2010-11-11
Publication date: 2012-05-18
Also published as: JPWO2012063348A1

Abstract

A laser processing method is provided with an application step for setting a light focusing part within an object to be processed and applying laser light to form a reformed region due to multiphoton absorption within the object to be processed, and a cutting step for forming a plurality of the reformed regions such that crack regions each formed around the reformed region are continuous from the surface on the reverse side to the laser light incidence surface side of the object to be processed to the surface on the laser light incidence surface side.

Description

Laser processing method and apparatus

The present invention relates to a technical field of a laser processing method and apparatus for performing processing such as cutting on an object to be processed by irradiation with laser light.

As this type of processing apparatus, an apparatus that forms a modified region locally embrittled by multiphoton absorption by condensing laser light on the surface or inside of a processing target such as a glass substrate is known. Yes. The following prior art documents describe a method of dividing a workpiece by adding a procedure such as cleavage, starting from a modified region formed inside the workpiece.

Further, the prior art document also describes a method of forming a notch for cutting on the outer periphery of a rod-like brittle workpiece by laser irradiation, and dividing by adding a side pressure to the notch. Such division of the processing object is used, for example, when forming an electronic component such as a chip. Various improvements are made to improve processing accuracy, such as improvement of flatness of a section of the processing object. Has been.

Japanese Patent No. 3408805 Japanese Patent No. 4399960

By the way, according to the method described in the above-mentioned prior art document, by forming a modified region inside the object to be processed, a line or the like serving as a starting point of division is formed, and cleaving along the line. Thus, the workpiece is divided. According to this method, a process of forming a starting line by laser light irradiation and a process of cleaving along the line are required, and facilities and mechanisms for realizing each process are required. Further, in this method, since the line formed by the modified region is only a part of the dividing surface, the dividing surface cannot be defined at the time of cleaving, and the flatness of the dividing surface cannot be managed. There is a technical problem with. In addition, when dividing by the lateral pressure, the flatness of the divided section cannot be managed in the same manner, and thus a large undulation may occur in the divided section. Thus, when the flatness of the divided surface of the workpiece after dividing is not sufficient, a process such as polishing of the divided surface is further required.

The present invention has been made in view of, for example, the above-described problems. In the case of dividing a workpiece by using laser light irradiation, the flatness of a divided section is improved and the number of steps is reduced. It is an object of the present invention to provide a laser processing method and apparatus capable of realizing processing.

In order to solve the above-mentioned problems, the laser processing method of the present invention forms a modified region by multiphoton absorption inside the processing object by irradiating the processing object with a laser beam with a condensing part inside. The irradiation step to be performed and the crack region formed around the modified region so as to continue from the surface opposite to the laser light incident surface side of the workpiece to the surface on the laser light incident surface side. And a cutting step of forming a plurality of the modified regions.

In order to solve the above-described problem, the laser processing apparatus of the present invention irradiates a laser beam by aligning a condensing portion inside a workpiece, and forms a modified region by multiphoton absorption inside the workpiece. And a crack region formed around the modified region so as to continue from the surface opposite to the laser light incident surface side of the workpiece to the surface on the laser light incident surface side. Cutting means for forming a plurality of the modified regions.

It is a block diagram which shows the aspect of the modification area | region and crack area | region formed in a process target object. It is a figure which shows the example of the division plan surface inside a process target object. It is a figure which shows the example of a pulsed laser beam. It is a table | surface which shows the example of the size of the modification area | region formed according to the irradiation conditions of a laser beam. It is a figure which shows the example of processing operation by irradiation of a laser beam. It is a figure which shows the example of processing operation by irradiation of a laser beam. It is a figure which shows the example of processing operation by irradiation of a laser beam. It is a figure which shows the example of processing operation by irradiation of a laser beam. It is a flowchart which shows the flow of the processing operation by irradiation of a laser beam. It is a block diagram which shows the structural example of a laser processing apparatus.

An embodiment of the laser processing method of the present invention includes an irradiation step of irradiating a laser beam with a condensing part inside a processing target, and forming a modified region by multiphoton absorption inside the processing target; The modified region is formed such that a crack region formed around the modified region is continuous from the surface opposite to the laser light incident surface side of the workpiece to the surface on the laser light incident surface side. A plurality of cutting steps.

In the embodiment of the laser processing method of the present invention, the processing target is irradiated with laser light, and the laser light is condensed on the surface or inside of the processing target. At this time, modification by multiphoton absorption occurs in the vicinity of the light condensing part, and a modified region is formed. The modified region is brittle compared to the region where no modification has occurred.

Also, cracks such as fine cracks may occur at the periphery of the modified region due to the action of internal stress accompanying the modification. A crack area | region is the meaning which shows the area | region where such a crack produced in the inside or surface of a workpiece. Such cracks are assumed to be caused by the action of stress due to thermal expansion due to excess energy accumulated in a region in the vicinity of the laser beam condensing portion inside the workpiece.

The size of each of the modified region and the crack region formed inside the object to be processed depends on the irradiation conditions such as the output and wavelength of the laser beam, the degree of light absorption according to the material of the object to be processed, etc. Change. Further, the modified region and the crack region have a three-dimensional shape such as a spherical shape, an ellipsoidal shape, or a cylindrical shape centering on the condensing portion of the laser beam. In particular, the ellipsoidal or cylindrical modified region and the crack region have their long axes in the optical axis direction of the laser light.

In the irradiation step, the inside of the workpiece is irradiated with a pulsed laser beam having a wavelength that can pass through the inside of the workpiece to at least the region that forms the modified region. For example, in the irradiation process, a laser light source capable of irradiating laser light and a condensing lens for condensing the irradiated laser light inside the object to be processed are used. Other laser light irradiation conditions will be described later.

In the cutting step, the laser beam condensing part is processed so that the crack region is continuously formed from the surface opposite to the laser beam incident surface side of the workpiece to the surface on the laser beam incident side. Move through things. The movement at this time may be relative, for example, one that fixes one and moves the other, or both that move simultaneously.

For example, in the cutting step, a lens unit that moves the condenser lens along the optical axis direction of the laser light by moving the condenser lens along the optical axis direction of the laser light, and a direction orthogonal to the optical axis direction of the laser light For example, a stage provided with an actuator for moving the workpiece is used.

According to the embodiment of the laser processing method of the present invention, in the surface (hereinafter, referred to as a planned splitting surface) where the processing target object is to be divided by the cutting process, A continuous crack region is formed from the surface opposite to the incident side to the surface on the incident side of the laser beam. By forming such a crack region, a small scratch or crack is formed from the surface opposite to the laser beam incident side to the surface on the laser beam incident side on the planned split surface, For example, it is possible to divide an object to be processed without adding a further process such as cleaving. For example, as performed in a general laser dicing method, a workpiece to be cut after cleaving is placed on a stretchable adhesive sheet, and easily separated by a so-called separation step by stretching the adhesive sheet. It becomes possible.

Furthermore, in the separation step, the workpiece is divided along the crack region that is continuously formed in this way, so that the flatness of the section after the division can be controlled. In particular, as will be described in detail later, by setting a short wavelength, a low average output, or a short pulse width for the laser beam to be irradiated, the modified region and the crack region formed inside the object to be processed are Get smaller. Therefore, according to the embodiment of the laser processing method of the present invention, it is possible to narrow the width of the planned cutting surface along the modified region and the crack region formed in the modified region, and the plane of the cut surface after dividing. The degree can be kept good.

In order to reduce the modified region and the crack region simply formed by laser light irradiation, it is conceivable to use an ultrashort pulse laser having a pulse width of femtoseconds or picoseconds. Japanese Patent No. 4054773 describes a technique for forming a crack in a silicon substrate using these laser beams. In the laser processing method according to the present embodiment, when a large number of small modified regions and crack regions are formed using such laser light, there is a possibility that a planned cutting surface with a narrower width can be formed. For this reason, the cutting | disconnection by the cut surface excellent in flatness from theory becomes possible.

On the other hand, in the case of using the above-described ultrashort pulse laser, the total irradiation time for forming a continuous crack region in the planned cutting plane is longer than in the case of using a short pulse laser such as a nanosecond laser. It is predicted. In an industrial scene where a processing method using laser irradiation is applied, there is a tendency that rapid processing is required for many processing objects. For this reason, the above-described ultrashort pulse laser is not suitable for processing when cutting a substrate or the like by laser light irradiation. Furthermore, processing using an ultrashort pulse laser requires a processing apparatus capable of accurately irradiating the ultrashort pulse laser, and there is a problem in industrial applicability due to an increase in installation cost.

On the other hand, according to the laser processing method of the present invention, it can be carried out if there is equipment that can irradiate laser light having a pulse width of nanosecond order, which is generally used at a relatively low installation cost. Further, the processing accuracy of the cut surface generally required for a substrate such as glass, crystal, silicon, or the like, which is a processing target, is about 20 to 50 μm in flatness. For this reason, the laser processing method of the present invention that satisfies the required processing accuracy and can be processed at a high speed also has the advantage of being excellent in industrial applicability.

In the present embodiment, it is preferable that a continuous crack region is formed from one end portion to the other end portion in the direction orthogonal to the optical axis on the planned cutting surface inside the workpiece. . That is, it is preferable that a crack region is formed over the entire parting planned surface inside the workpiece.

In another aspect of the embodiment of the laser processing method of the present invention, in the cutting step, the laser beam condensing unit or the laser beam so as to continuously form the crack region in a direction orthogonal to the optical axis of the laser beam. A first step of moving at least one of the workpieces and a second step of moving the laser beam condensing portion in the optical axis direction of the laser beam by a predetermined distance according to the size of the crack region are repeated. To be implemented.

In this aspect, the first step and the second step are repeatedly performed, so that the laser beam is incident from the surface opposite to the laser beam incident surface side on the planned split surface inside the workpiece. A continuous crack region can be formed up to the surface on the side.

For example, in the example using the lens unit described above and a stage including an actuator, the laser beam is collected in a direction orthogonal to the optical axis of the laser beam by moving the object to be processed while being irradiated with the laser beam. The optical part is scanned to form a continuous crack region line on the scanning path in the planned cutting plane.

Next, the lens unit moves the laser beam condensing part in the optical axis direction according to the size of the crack region. At this time, preferably, the crack region is continuously formed according to the size of the crack region that changes according to the irradiation condition of the laser light, the optical property of the workpiece, etc. (in other words, The moving distance is set so that the range covered by the crack region formed by the scan of the laser light after movement and at least the modified region formed by the scan before movement are in contact with each other.

According to this aspect, it is preferable to easily obtain a continuous crack region from the surface opposite to the laser light incident side to the surface on the laser light incident side, preferably within the planned split surface inside the workpiece. I can do it. For this reason, it is possible to eliminate the deficiency of the division due to the portion where the crack region is not formed on the planned division surface inside the object to be processed, and it is possible to increase the flatness of the cross section after the division.

Depending on the processing conditions, such as when the laser beam is scanned under relatively high irradiation conditions, or when the moving speed of the workpiece is relatively slow, A continuous reforming region line may be formed. It is known that further condensing part inside the reforming region leads to the formation of further reforming region and crack region, but as long as other conditions of this embodiment can be satisfied, the reforming region is continuous. It may be formed automatically. The laser beam irradiation conditions and the moving speed of the object to be processed that are preferable in carrying out this aspect will be described in detail later.

In another aspect of the embodiment of the laser processing method of the present invention, in the irradiation step, a plurality of the modified regions are formed at intervals of 10 μm to 90 μm in the optical axis direction of the laser light inside the processing object. .

According to this aspect, it is possible to set irradiation conditions that can suitably form a continuous crack region in the optical axis direction of the laser beam inside the workpiece. For this reason, it is possible to eliminate the deficiency of the division due to the portion where the crack region is not formed on the planned division surface inside the object to be processed, and it is possible to increase the flatness of the cross section after the division.

In another aspect of the embodiment of the laser processing method of the present invention, the irradiation step is performed under conditions that satisfy a condition that a pulse width is 5 ns to 20 ns, a repetition frequency is 15 kHz to 50 kHz, and an average output is 0.05 W to 0.2 W. Irradiating the laser beam, and in the cutting step, the laser beam condensing part is located inside the workpiece under the condition that the relative speed between the laser beam and the workpiece is 5 mm / s to 300 mm / s. At least one of the laser beam condensing unit or the workpiece is moved so as to move in a direction perpendicular to the optical axis of the laser beam.

According to this aspect, in laser processing using glass as a processing object, it is possible to appropriately set the emission condition of the pulsed laser beam. Under the above-described processing conditions, since the output of the laser beam is relatively small, the size of the modified region formed by multiphoton absorption inside the processing target and the surrounding crack region is also relatively small. For this reason, it is possible to obtain a continuous crack region on the planned dividing surface by forming a plurality of modified regions inside the workpiece and in the optical axis direction of the laser beam. For this reason, it is possible to eliminate the deficiency of the division due to the portion where the crack region is not formed on the planned division surface inside the object to be processed, and it is possible to increase the flatness of the cross section after the division.

In another aspect of the embodiment of the laser processing method of the present invention, in the irradiation step, the laser beam having a wavelength of 355 nm is irradiated.

In this aspect, since the wavelength of the laser for laser processing is relatively short, it is possible to form a laser beam condensing part in a relatively small region. As a result, a modified region by multiphoton absorption can be formed inside a relatively small region in the condensing unit, and the influence of heat generated by laser light irradiation on the region other than the condensing unit can be reduced. .

In another aspect of the embodiment of the laser processing method of the present invention, the object to be processed has transparency to the laser light.

For this reason, it is possible to reduce the absorption of the laser beam in the region other than the laser beam condensing portion inside the processing target and to suitably transmit the laser beam to a desired depth for the internal processing. Become. Even when the object to be processed is transparent to the laser beam, if the output of the laser beam is sufficiently high, a modified region is formed by multiphoton absorption. It becomes possible. Note that the output of the laser beam and other optical properties of the workpiece may be arbitrarily determined within a range where the multiphoton absorption is sufficiently generated unless otherwise specified.

In another aspect of the embodiment of the laser processing method of the present invention, the object to be processed is a laminate of a plurality of substrates.

The object to be processed in which a plurality of substrates are bonded in this aspect is a so-called bonded glass or the like by bonding a plurality of substrates such as glass or quartz with an adhesive or the like. In the embodiment of the laser processing method, since a crack region is continuously formed from the surface opposite to the laser beam incident side of the workpiece to the laser light incident side surface, a plurality of substrates are bonded together. Even if it is a processed object, a continuous crack region is formed on each substrate. For this reason, it becomes possible to easily divide the object to be processed having a continuous crack region as a section.

As described above, when a laser beam having a wavelength of 355 nm and an average output of 0.05 W to 0.2 W is used for processing, it is possible to suppress deterioration that occurs in the adhesive that bonds the substrates, and further suitable processing is possible. .

An embodiment of the laser processing apparatus of the present invention includes an irradiation unit that irradiates a laser beam with a condensing unit inside a processing target, and forms a modified region by multiphoton absorption inside the processing target; The modified region is formed such that a crack region formed around the modified region is continuous from the surface opposite to the laser light incident surface side of the workpiece to the surface on the laser light incident surface side. And a cutting means for forming a plurality of.

Embodiment of the laser processing apparatus of this invention is an apparatus for implement | achieving the laser processing method mentioned above, for example. The laser processing apparatus includes, as irradiation means, for example, a laser light source that irradiates laser light of a predetermined condition, and a condensing lens that condenses the laser light inside the object to be processed to form a condensing unit. . The laser processing apparatus includes, as cutting means, for example, a lens unit capable of driving a condenser lens as described above, and a stage provided with an actuator.

Incidentally, in response to various aspects that the above-described embodiment of the laser processing method can take, the embodiment of the laser processing apparatus may also adopt various aspects.

As described above, the embodiment of the laser processing method of the present invention includes a condensing step and a cutting step. An embodiment of the laser processing apparatus of the present invention includes a light collecting means and a cutting means.

For this reason, it is possible to eliminate the deficiency of the division due to the portion where the crack region is not formed on the planned division surface inside the workpiece, and to make the flatness of the cross-section after the division high.

Embodiments of the present invention will be described with reference to the drawings.

(1) Example of implementation of laser processing method The laser processing method of the present invention condenses laser light so as to form a condensing part inside a workpiece, and modifies the condensing part by multiphoton absorption. A region and a crack region are formed. In the present embodiment, the formed modified region and the crack region are used to divide the workpiece using the modified region and the crack region by utilizing the fact that the modified region and the crack region are embrittled compared with the region where the modification is not generated. A method will be described.

An outline of the division of the workpiece using the modified region and the crack region will be described with reference to the drawings. FIG. 1 is a cross-sectional view taken along a direction orthogonal to the optical axis of a laser beam L1 for processing a workpiece 1 to be laser processed.

Processing object 1 is a substrate made of glass or quartz. The workpiece 1 is capable of transmitting the laser beam L1 used for laser processing (that is, optically transparent), and has an optical property that multiphoton absorption occurs when the intensity of the laser beam L1 is high.

When the condensing part F1 of the laser beam L1 is formed inside the workpiece 1 and the condition for multiphoton absorption is satisfied in the condensing part F1, modification by multiphoton absorption is performed in the vicinity of the condensing part F1. And a modified region R is formed. Further, a crack region C in which cracks such as fine cracks are generated due to the action of internal stress accompanying the modification is formed outside the modified region. The modified region R and the crack region C are typically regions that are substantially similar to each other, and are an ellipsoid having a major axis in the optical axis direction of the laser light L1, and a cylinder having the axial direction in the direction. Or spherical shape. This is because more multiphoton absorption of the laser light L1 occurs in the optical axis direction in the vicinity of the condensing part F1.

In the present embodiment, the laser beam L1 has a wavelength of 355 nm, a pulse width of 5 to 20 ns, a repetition frequency of 15 to 50 kHz, and an average output of 0.05 to 0.05, with the condensing unit F1 inside the workpiece 1. Irradiation is performed under the condition of 0.2W.

The laser light source that irradiates the laser beam L1 irradiates the pulsed laser beam L1 in accordance with the trigger signal shown in FIG. The trigger signal is a signal input from a control device or the like for controlling the laser light source, and is a pulse signal having a repetition frequency of 15 to 50 kHz described above (in other words, a repetition cycle based on the repetition frequency). The laser light source receives the trigger signal and irradiates the laser light L1 under the above-described conditions of wavelength, pulse width, and average output. The pulse width is, for example, the half width of one pulse of the laser light L1, and is defined in the form of a time length. The average output is obtained by averaging the output of the laser beam L1 within one cycle of the trigger signal repetition cycle.

Under the conditions, the modified region R and the crack region C are formed by multiphoton absorption occurring in the light collecting portion F1, while the surface 1a on the incident side of the laser beam L1 of the workpiece 1 is, for example, Further, there is no modification or melting due to absorption of the laser beam L1.

Under the above-described conditions, since the average output is relatively low, the formed modified region R and crack region C are relatively small. FIG. 4 is a table showing an example of the length of the modified region R in the optical axis direction of the laser beam L1 under the above conditions. The table shown in FIG. 4 shows that the laser light L1 has a wavelength of 355 nm, an aperture NA of the condensing lens used for condensing NA0.5, a diameter of the condensing part F1 of about 900 nm, and an average output of 0.1 W. The length in the optical axis direction of the laser beam L1 of the modified region R formed when the processing unit 1 is irradiated with the condensing part F1 is shown. Under these conditions, when the workpiece 1 is quartz, a modified region R having a length of 20 to 60 μm is formed in the optical axis direction of the laser beam L1, and when the workpiece 1 is glass, A modified region R having a length of 20 to 50 μm is formed in the optical axis direction of the laser beam L1.

The laser processing method according to the present embodiment divides the workpiece 1 by continuously forming the modified region R and the crack region C in the planned dividing surface. FIG. 2 is a perspective view of the workpiece 1. In the laser processing method according to the present embodiment, the laser beam L1 is set so that the planned division surface 2 is virtually set on the workpiece 1, and the modified region R and the crack region C are formed along the planned division surface 2. Irradiation and condensing.

With reference to FIG. 5 thru | or FIG. 7, the example of irradiation and condensing of the laser beam L1 at the time of forming the modification area | region R and the crack area | region C which concern on the process of the process target object 1 is demonstrated. FIG. 5 to FIG. 7 are cross-sectional views along the scheduled cutting surface 2 (XZ plane) of the workpiece 1 to be laser processed, and explain the processing procedure.

As shown in FIG. 5, the condensing part F1 is aligned at a position separated from the surface 1b facing the surface 1a of the workpiece 1 by a predetermined distance d, a wavelength of 355 nm, a pulse width of 5 to 20 ns, a repetition frequency of 15 to 50 kHz, The laser beam L1 is irradiated under the condition that the average output is 0.05 to 0.2W.

The distance d is a distance at which the surface 1b is not crushed by the influence of the modified region R and the crack region C formed by the irradiation of the laser beam L1, and the distance at which the crack region C reaches the surface 1b. Is set. For this reason, it is preferable that the distance d is appropriately set according to the irradiation condition of the laser light L1 and the material of the workpiece 1 (more specifically, properties related to light absorption such as a band gap). Note that the term “crushing” means not only that the crack region reaches the surface but also a state in which the surface is actually divided into pieces. When crushing occurs in this way, it leads to deterioration of flatness in the planned dividing surface 2 and is not preferable because it causes unevenness in the divided section when the workpiece 1 is divided.

For example, in the experiment by the inventors of the present invention, in the irradiation with the laser beam L1 having a wavelength of 355 nm, the distance d is 0.5 times the size of the modified region R in the optical axis direction (that is, the modified region R It has been reported that crushing occurs on the surface when the length from the center to one end) +15 μm. On the other hand, when the distance d is 0.5 times the size of the modified region R in the optical axis direction (that is, the length from the center of the modified region R to one end) +20 μm, the surface is crushed. In addition, it has been reported that the crack region reaches the surface.

Next, as shown in FIG. 6 (a) or (b), the laser beam L1 is scanned in the direction perpendicular to the optical axis of the laser beam L1 inside the object 1 to be processed. Move in the direction. At this time, for example, the laser beam L1 may be scanned by moving the workpiece 1 in the opposite direction (for example, the −X direction) in which scanning is performed while the irradiation of the laser beam L1 is maintained. . The scan is performed under the condition that the relative speed (in other words, the scan speed) between the laser beam L1 and the workpiece 1 is 5 to 300 mm / s. An apparatus configuration for performing such scanning may be arbitrary, and an example will be described later.

At this time, the laser beam L1 is scanned at a speed of 5 to 300 mm / s. For example, in the above-described example, the workpiece 1 is moved in the opposite direction in which scanning is performed under the above-described conditions. By such scanning, the modified region R can be continuously (for example, see FIG. 6B) or discontinuously (for example, see FIG. 6A) on and near the movement path of the light collecting portion F1. Is formed. As shown in FIG. 6A, hereinafter, the distance between adjacent reformed regions R formed discontinuously (for example, the distance on the X axis between the center points of the respective reformed regions R) is defined as dR. Is described. The case where the modified region R is continuously formed is a case where the distance dR is sufficiently small. Further, a crack region C is continuously formed in the vicinity of the modified region R. Preferably, the laser beam L1 is scanned so that the crack region C extends from one end portion in the direction orthogonal to the optical axis in the planned splitting surface 2 to the other end portion.

Next, as shown in FIG. 7, the laser beam condensing part F 1 is moved to the optical axis direction incident side (Z direction in FIG. 7) by a predetermined distance p. The distance p is defined as 10 to 90 μm. By moving the condensing unit F1 in this way, the modified region R formed by irradiation before moving the condensing unit F1 and the modified region R formed by irradiation after moving, or at least before moving The crack region C formed by the irradiation and the crack region C formed by the irradiation after the movement are continuous.

Thereafter, the scan shown in FIG. 6A or 6B is performed in a state where the position of the light collecting portion F1 in the optical axis direction (in other words, the depth in the workpiece 1) is maintained.

After forming the continuous crack region C as shown in FIGS. 6 and 7 along the planned cutting surface 2, as shown in FIG. 8, the surface 1a on the incident side of the laser beam L1 of the workpiece 1 is described above. The laser beam L1 is scanned by aligning the condensing unit F1 at positions separated by a distance d. By this scanning, a crack region C continuously formed along the planned dividing surface 2 reaches from the surface 1b to the surface 1a. After the scan at the position separated from the surface 1a by the distance d is completed, the irradiation of the laser beam L1 on the planned split surface 2 is completed. At this time, the scan position does not necessarily have to be the distance d, and may preferably be a distance shorter than the distance d as long as the above-described crushing does not occur.

The flow of operations in the laser processing method described above is summarized in the flowchart of FIG. In the laser processing method according to the embodiment, at the start of processing, processing conditions are set within the above-described range in accordance with the material or the like of the processing object 1 (step S101). Specifically, with respect to the irradiation condition of the laser beam L1, the pulse width is determined within the range of 5 to 20 ns, the repetition frequency is 15 to 50 kHz, and the average output is within the range of 0.05 to 0.2 W. At this time, the distance d of the condensing portion F1 from the surface 1b when condensing the laser light L1 for the first time, the moving distance p of the condensing portion F1 after scanning, the laser light L1 during scanning and the object to be processed A scanning speed that is relative to 1 is determined. Specifically, the distance d is determined according to the material of the workpiece 1, the thickness in the optical axis direction, the size of the modified region R and the crack region C formed by irradiation with the laser light L 1, and the like. p is determined from the range of 10 to 90 μm. Further, the relative speed between the laser beam L1 and the workpiece 1 during scanning is determined within a range of 5 to 300 mm / s.

Subsequently, the laser beam L1 irradiated under the conditions set in step S101 is placed at a distance d from the surface 1b opposite to the laser beam L1 incident side of the workpiece 1 using a condenser lens or the like. Condensing light (step S102). Then, the laser beam L1 is scanned by moving the workpiece 1 in a direction orthogonal to the optical axis (step S103). After the scan is completed, the condensing part F1 of the laser light L1 is moved by a distance p in the optical axis direction and in the surface 1a direction by moving the condensing lens (step S104). Steps S 103 and S 104 are repeated until the condensing unit F 1 is at a distance d or less from the surface 1 a of the workpiece 1. When the condensing unit F1 is at or below the distance d from the surface 1a of the workpiece 1 (step S105: Yes), the machining operation is terminated after the laser beam L1 is scanned at the position (step S106).

As described above, according to the processing of the object to be processed by the laser light irradiation described above, the crack region is continuously formed from the surface 1b to the surface 1a along the planned dividing surface 2 inside the object 1 to be processed. Because of such a continuous crack region, for example, without performing a process such as cleaving, by performing a process for separating the processing object performed after the cleaving process in a general laser dicing method, the processing object can be divided. It becomes possible. This is because small scratches and cracks are continuous from the surface 1a to 1b inside the planned split surface where the crack region is continuously formed, and therefore can be easily separated without applying a large force.

In addition, since the relatively small crack region is continuously formed under the laser light irradiation conditions and the processing conditions described above, the size of the crack region extending in the direction perpendicular to the planned cutting surface is also compared inside the object to be processed. Small. Therefore, when the separation is performed along the planned dividing surface, the dividing surface can be controlled while maintaining the flatness of the dividing surface with relatively high accuracy. For example, a flatness of about 20 μm can be realized for glass, quartz, etc., and a flatness of about 50 μm can be realized for a laminated glass obtained by bonding a plurality of substrates with an adhesive. Since such a highly accurate cross section can be obtained, the polishing of the cross section after the division may be omitted.

For example, the same effect can be obtained when a laminated glass or the like obtained by bonding a plurality of substrates such as glass or crystal with an adhesive is used as the workpiece 1. Further, under the processing conditions described in the present embodiment, the influence of the laser light L1 on the adhesive of the laminated glass can be suppressed, and further, the deterioration of the adhesive can be suppressed because there is little absorption of the 355 nm laser light. . Generally, in the prior art, when trying to cut the laminated glass as described above, the portion of the adhesive is altered by the laser beam, and the influence is great.

In addition, since the wavelength of the laser beam L1 is relatively short, the numerical aperture of the condensing lens for condensing the laser beam L1 to cause multiphoton absorption in the condensing unit F1 is relatively small. For this reason, it is preferable that the optical path of the laser beam L1 passes outside the end of the workpiece 1 in an end portion parallel to the optical axis in a direction perpendicular to the optical axis on the planned cutting surface of the workpiece 1. Can be suppressed. For this reason, the crack region C is continuously formed from one end portion to the other end portion even in the end portion parallel to the optical axis in the direction perpendicular to the optical axis on the planned cutting surface of the workpiece 1. Preferably, the crack region C can be formed over the entire parting planned surface 2. Thereby, division | segmentation becomes still easier and the improvement of the flatness of the cross section after division | segmentation can be aimed at.

(2) Processing Conditions and Effects Results of experiments performed by the inventors of the present invention will be described with respect to the above-described irradiation conditions of the laser beam L1 and processing conditions such as the scanning speed during processing. In addition, about the following results, after dividing the process target object 1 along the division parting surface 2, what has a favorable cross-section flatness is classify | categorized as a favorable process. The flatness of the cross section judged to be good processing is, for example, 20 μm when the workpiece 1 is made of a single plate glass, and 50 μm when a plurality of substrates such as glass or quartz are laminated. Yes.

Regarding the pulse width of the laser beam L1, good processing is observed under the conditions of 5.0 ns, 6.0 ns, 7.0 ns, 12.0 ns, 14.0 ns, and 20.0 ns, while the pulse width is 22 Good processing was not observed in the region exceeding 20.0 ns of 0.0 ns and 24.0 ns.

Further, under the conditions of the wavelength and pulse width of the laser beam set as described above, the interval dR between the modified regions R formed by scanning varies depending on the repetition frequency of the laser beam L1 and the scan speed. Depending on the distance dR of the modified region R at this time, the flatness of the divided section after the division is affected. About this influence, the result of experiment of the inventors about the case where favorable processing is observed like the above-mentioned thing is demonstrated. In general, the relationship dR (μm) = scanning speed (mm / s) / repetition frequency (kHz) is established with respect to the interval dR between the modified regions R to be formed.

When the repetition frequency is 15 kHz, the interval dR is 0.7 μm when the scanning speed is 10 mm / s, the interval dR is 6.7 μm when the scanning speed is 100 mm / s, and the interval is when the scanning speed is 200 mm / s. dR was 13.3 μm, and good processing was observed in all cases. When the scanning speed was 300 mm / s, the interval dR was 20.0 μm, and good results were not observed.

When the repetition frequency is 20 kHz, the spacing dR is 0.3 μm when the scanning speed is 5 mm / s, and the spacing dR is 5.0 μm when the scanning speed is 100 mm / s, and good processing is observed in both cases. It was.

When the repetition frequency was 30 kHz, when the scanning speed was 300 mm / s, the interval dR was 10.7 μm, and good processing was observed. When the scanning speed was 400 mm / s, the distance dR was 13.3 μm, and good results were not observed.

When the repetition frequency was 35 kHz, when the scanning speed was 100 mm / s, the interval dR was 2.9 μm, and good processing was observed.

When the repetition frequency is 50 kHz, the spacing dR is 2.0 μm when the scanning speed is 100 mm / s, and the spacing dR is 4.0 μm when the scanning speed is 200 mm / s, and good processing is observed in both cases. It was.

From the above results, good processing is observed until the distance dR between the modified regions R to be formed is about 13.3 μm, and good processing is not observed in the region beyond that. For this reason, it is possible to realize good processing by selecting the repetition frequency and the scanning speed within the specified ranges as described above.

(3) Configuration Example of Laser Processing Apparatus An example of a laser processing apparatus for implementing the laser processing method of the above-described embodiment will be described with reference to the drawings. FIG. 10 is a diagram showing a device configuration of the laser processing device 3.

As shown in FIG. 10, the laser processing apparatus 3 includes a control unit 10, a laser power source 11, a laser light source 12, a mirror 13, a half-wave plate 14, a mirror 15, and a beam expander 16. A beam combiner 17, a lens block 18, and a condenser lens 19. The laser processing apparatus 3 includes a guide laser diode (LD) 21 and a guide optical system 22.

The control unit 10 is an example of a control unit of the present invention, and includes a CPU that controls the operation of each unit of the laser processing apparatus 3. The control unit 10 controls the operations of the laser power source 11 and the laser light source 12 so as to emit laser light L1 that is pulse-like and satisfies emission conditions such as a predetermined repetition frequency, average output, and pulse peak output. Moreover, the control part 10 controls operation | movement of the lens block 18 so that the position of the condensing part F1 of the laser beam L1 may be changed with the process of the workpiece 1 by emission of the laser beam L1. Moreover, the control part 10 performs control which moves the stage 40 which mounts the workpiece 1 in the surface orthogonal to the optical axis direction of the laser beam L1, etc. with the emission of the laser beam L1.

The laser power source 11 includes a power source for supplying power for driving the laser light source 12 and a pulse control device. For example, the laser power source 11 receives an instruction input by a user and supplies current to the laser light source in a desired manner. Do and drive.

The laser light source 12 includes a laser generator, a crystal element, a phase modulator, a resonator, and the like, generates a laser beam L1 according to a current supplied from the laser power source 11, and emits the laser beam L1 toward the mirror 13. The laser light source 12 is preferably a light source excellent in pulse control and output control.

The laser light L 1 emitted from the laser light source 12 is adjusted in phase difference or polarization state in the half-wavelength plate 14 through the mirror 13 and then enters the beam expander 16 through the mirror 15.

The beam expander 16 is a mechanism that expands the beam diameter of the laser light L1 that is incident in the form of parallel light. Specifically, the beam expander 16 adjusts so that the beam diameter of the condensing part F1 in the processing target 1 of the laser light L1 is within a predetermined range, together with condensing by the condensing lens 19 described later. . The expansion ratio of the beam diameter by the beam expander 16 is set according to the aperture of the condenser lens 19 described later.

The beam combiner 17 is a half mirror or the like that combines the laser beam L1 on the same optical path by transmitting the laser beam L1 and reflecting the laser beam L2 for guide.

The guide laser beam L2 is a laser beam emitted from the guide LD 21, and is incorporated in the same optical path as the laser beam L1 by the beam combiner 17, and is condensed on the workpiece 1 by the condenser lens 19. Laser light for distance measurement or servo drive. On the optical path of the laser beam L2, a guide optical system 22 corresponding to the application, such as a beam shaping lens, a condensing lens, or a cylindrical lens, is disposed.

The lens block 18 is a lens unit that holds the condenser lens 19 and includes a slide mechanism that moves the condenser lens 19 in the optical axis direction of the laser light L1.

The condensing lens 19 is a lens that mainly condenses the laser light L1 on the surface or inside of the workpiece 1 and typically forms a condensing part F1 at the focal position. The aperture of the condenser lens 19 is preferably set in accordance with the beam diameter of the condenser part F1. For example, the lens block 18 moves the condensing lens 19 in the optical axis direction of the laser light L1 in accordance with a control signal from the control unit 10, thereby condensing the lens block 18 at a desired position on the surface of the workpiece 1 or inside. Move part F1.

The stage 40 is a mounting table on which the workpiece 1 is mounted. Further, the stage 40 may include a mechanism capable of moving the workpiece 1 in a plane orthogonal to the optical axis direction of the laser light L1. In the case of including such a mechanism, the stage 40 moves the workpiece 1 at a speed according to the control signal supplied from the controller 10, thereby moving the workpiece 1 to the condensing unit F 1 for the laser light L 1. It is possible to move relative to it. In addition, the laser processing apparatus 3 may be provided with the mechanism which can move relatively the other workpiece 1 and the condensing part F1 of the laser beam L1.

The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification, and a laser processing method involving such changes Also, devices and the like are also included in the technical scope of the present invention.

C crack region,
R reforming region,
1 Processing object 2 Planned cutting surface 3 Laser processing equipment,
10 control unit,
11 Laser power source 12 Laser light source,
13, 15 mirror,
14 1/2 wavelength plate,
16 beam expander,
17 Beam combiner,
18 Lens block,
19 Condensing lens,
40 stages,
50 processing object,
L1 (for processing) laser light,
L2 (for guide) laser light.

Claims

An irradiation step of irradiating a laser beam with a condensing part inside the object to be processed, and forming a modified region by multiphoton absorption inside the object to be processed,
The modified region is formed such that a crack region formed around the modified region is continuous from the surface opposite to the laser light incident surface side of the workpiece to the surface on the laser light incident surface side. And a cutting step of forming a plurality of the laser processing method.
In the cutting step,
A first step of moving at least one of the condensing portion of the laser light or the processing object so as to continuously form the crack region in a direction orthogonal to the optical axis of the laser light;
2. The laser according to claim 1, wherein the second step of moving the laser beam condensing unit by a predetermined distance according to the size of the crack region in the optical axis direction of the laser beam is repeatedly performed. Processing method.
3. The laser processing according to claim 1, wherein, in the irradiation step, a plurality of the modified regions are formed at intervals of 10 μm to 90 μm in the optical axis direction of the laser light inside the workpiece. Method.
In the irradiation step, the laser beam is irradiated under the conditions that the pulse width is 5 ns to 20 ns, the repetition frequency is 15 kHz to 50 kHz, and the average output is 0.05 W to 0.2 W.
In the cutting step, the laser beam condensing unit moves the inside of the workpiece to the optical axis of the laser beam under the condition that the relative speed between the laser beam and the workpiece is 5 mm / s to 300 mm / s. 4. The laser processing method according to claim 1, wherein at least one of the laser beam condensing unit or the processing target is moved so as to move in an orthogonal direction. 5.
The laser processing method according to any one of claims 1 to 4, wherein in the irradiation step, the laser beam having a wavelength of 355 nm is irradiated.
The laser processing method according to any one of claims 1 to 5, wherein the object to be processed has transparency to the laser light.
The laser processing method according to any one of claims 1 to 6, wherein the object to be processed is a laminate of a plurality of substrates.
An irradiation unit that irradiates a laser beam with a condensing part inside the processing target, and forms a modified region by multiphoton absorption inside the processing target;
The modified region is formed such that a crack region formed around the modified region is continuous from the surface opposite to the laser light incident surface side of the workpiece to the surface on the laser light incident surface side. And a cutting means for forming a plurality of laser processing devices.