JP2007284288A - Substrate scribing method and scribing apparatus - Google Patents

Abstract

A substrate scribing method and a scribing apparatus capable of reliably forming a modified portion.
Laser light is condensed by a condenser lens and irradiated into a substrate to form a modified portion. When the modified portion 35 is normally formed, the plasma light 45 is emitted from the place where the laser light 44 is collected. The plasma light 45 is detected by the plasma light detector 12, and the light intensity of the plasma light 45 is compared with a threshold value to estimate the quality of the modified portion 35 to be formed. When the light intensity of the plasma light 45 is weak and the reforming part 35 to be formed is judged to be defective, the laser beam 44 is condensed again and irradiated to the place where the reforming part 35 becomes defective, and the reforming part 35 is irradiated. 35 is formed.
[Selection] Figure 5

Description

  The present invention relates to a method for scribing a substrate and a scribing apparatus.

Patent Document 1 discloses a laser scribing method for irradiating a substrate with laser light to form a modified region (hereinafter referred to as a modified portion) inside the substrate in order to cut a light-transmitting substrate with high quality. Has been. According to this, laser light having a pulse width of 1 μs or less is emitted and condensed inside the substrate by a condensing lens so that the peak power density at the condensing point is 1 × 10 ⁸ (W / cm ² ) or more. Thereby, the modified part by multiphoton absorption is formed inside the workpiece.

In this laser scribing method, the size of the modified portion formed inside the object to be processed or the modified portion formed from this depends on the characteristics of the condenser lens and the peak power density of the laser beam. Dependent. For example, in the embodiment in which the glass (thickness 700 μm) disclosed in Patent Document 1 is cut using a YAG laser, the peak power density is about 1 × 10 ¹¹ when the numerical aperture of the condenser lens is 0.55. In (W / cm ² ), the size of the modified portion is approximately 100 μm. Further, when the peak power density is about 5 × 10 ¹¹ (W / cm ² ), it is about 250 μm. By forming the reforming portions in the substrate and pressing the reforming portions, the substrate can be divided along the reforming portions with good quality.

JP 2002-192371 A

  However, when the modified portion is not normally formed, such as when the light intensity of the laser light emitted from the laser light source is weak, there is a possibility that the substrate will be broken and the substrate may be damaged if the substrate is divided.

  The present invention has been made in consideration of the above-described problems, and an object of the present invention is to provide a substrate scribing method and a scribing apparatus in which a modified portion can be reliably formed.

  In order to solve the above problems, the scribing method of the present invention is a scribing method in which a substrate that transmits visible light is irradiated with a laser beam to scribe, and the laser beam is condensed inside the substrate to modify the modified portion. It is characterized by detecting plasma light that is emitted when forming the film, and determining whether the modified portion is good or not based on the intensity of the detected plasma light.

According to this scribing method, the modified portion is formed by condensing the laser beam in the substrate. When forming the reforming portion, the constituent material of the substrate is excited in a place where the laser light is condensed, and enters a plasma state, and the plasma light is emitted. The light intensity of the plasma light and the dimension of the modified portion to be formed are formed approximately in proportion. Therefore, the light intensity of the plasma light can be detected, and the dimensions of the modified portion can be estimated from this light intensity. It can be determined whether the dimension of the reforming part is larger or smaller than the desired dimension.
The dimension of the reforming part indicates a value obtained by measuring attributes such as the length, width, and volume of the formed reforming part, or a value obtained by calculating the measurement value by a combination of four arithmetic operations. . Large dimensions of the reforming part indicate that the length, width, and volume of the reforming part are large.

  The scribing method of the present invention provides a light intensity threshold value based on the correlation between the light intensity of plasma light and the dimensions of the modified portion, and when the light intensity of the generated plasma light is weaker than the threshold value when scribing to the substrate, the same is applied. The modified portion is formed by condensing the laser beam again at the place.

  According to this scribing method, the correlation between the light intensity of the plasma light emitted when the modified portion is formed and the dimensions of the formed modified portion is obtained, and the modified portion has a desired size. The light intensity of the plasma light is obtained and set as a threshold value. In order to scribe the substrate, the strength of the plasma light emitted when the modified part is formed is determined as compared with a threshold value, and the dimension of the modified part is compared with the desired dimension. The size is estimated and judged. Therefore, by comparing the light intensity of the plasma light with the threshold value without directly measuring the dimensions of the modified portion, it is possible to estimate and determine the size of the modified portion with respect to the desired size.

  In the scribing method of the present invention, the modified portion is formed by moving the position where the laser beam is sequentially focused on the substrate. When the plasma light when forming the modified portion is weaker than the threshold value, the modified portion is formed on the substrate. A place where the laser beam is condensed again at a place where the plasma light is weaker than the threshold value without moving the place where the formation is to be performed, and the modified part is formed. The array of the reforming portions is formed by repeating the step of forming the reforming portion by moving the.

  According to this scribing method, the light intensity of the plasma light is compared with a threshold value, and when the modified portion whose volume is smaller than the desired volume is formed, the laser beam is condensed again to form the modified portion. ing. Therefore, the reforming part having a small size of the reforming part can form the reforming part again, and can form an array of reforming parts having a dimension of the reforming part of a desired size or more.

  The scribing method of the present invention moves the place where laser light is sequentially focused on the substrate to form a modified part, stores the place where the plasma light when forming the modified part is weaker than the threshold, and stores the stored place The laser beam is condensed again to form a modified portion.

  According to this scribing method, the place where the laser beam is condensed is sequentially moved inside the substrate to form the modified portion. The light intensity of the plasma light emitted when forming the modified portion is compared with a threshold value, and a place where the size of the modified portion is estimated to be smaller than a desired size is stored. In the course of forming the array of the reforming portions, the reforming portion can be formed by sequentially moving to a place where the dimensions of the reforming portions are estimated to be smaller than the desired dimensions, and condensing the laser beam.

  When the light intensity of the plasma light is weaker than the threshold value, the method of forming the modified portion by stopping the movement of the substrate and irradiating the laser light again moves to the irradiation position of the laser light every time the laser light is irradiated. It will be necessary to decide whether to continue or stop. During the determination, the substrate is not moved during the determination, and the determination is made to move to the next irradiation place.

  On the other hand, after forming the modified part array without stopping the movement of the substrate and forming the modified part in a predetermined region, the modified part is moved sequentially to a place where the light intensity of the plasma light is weaker than the threshold value. The method of forming the substrate can continue the movement of the substrate for a predetermined period.

  Therefore, when the light intensity of the plasma light is smaller than the threshold value, the location where the plasma light intensity is smaller than the threshold value is memorized compared with the method of stopping the movement of the substrate and irradiating the laser light again to form the modified portion. Thus, the substrate can be moved faster if the substrate movement is continued for a predetermined period. As a result, it is possible to scribe with high productivity.

  In order to solve the above problems, a scribing apparatus of the present invention is a scribing apparatus that irradiates a substrate with laser light and scribes the laser light source that emits laser light, and condenses the laser light inside the substrate. A light converging part for forming a reforming part, a plasma light detector for detecting plasma light emitted when the reforming part is formed, and a light intensity of the plasma light detected by the plasma light detector. Further, it is characterized by having a pass / fail judgment section for judging pass / fail of the reforming section.

  According to this scribing apparatus, the laser beam is condensed inside the substrate to form the modified portion, and the detecting portion detects the plasma light emitted when the modified portion is formed. Furthermore, it has a pass / fail judgment section for judging pass / fail of the reforming section from the light intensity of the plasma light detected by the detector. Based on the result of the pass / fail judgment, the modified portion can be formed again by irradiating the place where the modified portion is defective with the laser beam again. Therefore, it can be set as the scribing apparatus which can form a modification part with sufficient quality.

  The scribing apparatus of the present invention is characterized in that a filter that transmits a specific wavelength is installed in the plasma detector.

  According to this scribing device, the filter is installed in the detector. Since the light intensity of plasma light is detected from light having a wavelength effective for detection, the influence of light other than plasma light can be reduced. Therefore, plasma light can be detected with high accuracy.

  The scribing device according to the present invention is characterized in that the plasma detector is arranged so that a place for condensing the laser light enters a range in which the plasma light can be detected.

  According to this scribing apparatus, even if the position for condensing the laser beam in the substrate moves, it is possible to detect the plasma light emitted from the converging location. Can be judged.

  In order to solve the above-mentioned problems, the scribing apparatus of the present invention is characterized in that the distance between the location where the laser beam is collected and the plasma detector is maintained at substantially the same distance.

  According to this scribing apparatus, since the distance between the laser beam condensing place and the plasma detector is maintained at substantially the same distance, the laser light is collected at a plurality of places where the laser light is condensed within the substrate. The distance between the light source and the plasma detector is maintained at substantially the same distance. Plasma light is emitted in three dimensions from the light source, and the emitted light intensity attenuates in inverse proportion to the square of the distance from the light source. Since the distance between the location where the laser beam is collected and the plasma detector is maintained at substantially the same distance, the detection error of the light intensity due to the location where the plasma beam is detected can be reduced.

Embodiments of the present invention will be described below with reference to the drawings.
In addition, each member in each drawing is illustrated with a different scale for each member in order to make the size recognizable on each drawing.

(First embodiment)
A laser scribing method according to a first embodiment of the present invention will be described with reference to FIGS.

First, the laser irradiation apparatus will be described. FIG. 1 is a schematic diagram showing a configuration of a laser irradiation apparatus.
As shown in FIG. 1, the laser irradiation apparatus 1 includes a laser light source 2 that emits laser light, an optical path unit 3 that irradiates the work with the emitted laser light, and a work relative to the optical path unit 3. The table unit 4 is moved mainly and the control device 5 for controlling the operation is mainly configured.

The laser light source 2 may be any light source that can collect the emitted laser light inside the object to be processed and form a modified portion by multiphoton absorption. In the present embodiment, for example, the laser light source 2 is made of a laser medium of LD pumped Nd: YAG (Nd: Y ₃ Al ₃ O ₁₂ ), and a third harmonic (wavelength: 355 nm) Q-switch pulse oscillation laser light is used. The emission conditions for emission were adopted. The light emission conditions for emitting a laser beam having a pulse width of about 14 ns (nanoseconds), a pulse period of 10 kHz, and an output of about 60 μJ / pulse were adopted.

  The optical path unit 3 includes a dichroic mirror 6. The dichroic mirror 6 is disposed on the optical axis 7 of the laser light emitted from the laser light source 2. The dichroic mirror 6 reflects the laser light emitted from the laser light source 2 and changes the traveling direction of the optical axis 7. A condenser lens 8 is disposed on the optical axis 7 through which the laser light reflected by the dichroic mirror 6 passes. A work 9 is arranged on the table portion 4, and the work 9 is irradiated with the laser light condensed by the condenser lens 8.

The condenser lens 8 is supported by the lens moving mechanism 11 by the lens support portion 10. The lens moving mechanism 11 has a linear motion mechanism (not shown), and moves the condensing lens 8 in the direction of the optical axis 7 so that the location where the laser light that has passed through the condensing lens 8 is condensed can be moved.
The linear motion mechanism is, for example, a screw type linear motion mechanism provided with a screw shaft (drive shaft) extending in the Z direction and a ball nut screwed to the screw shaft, and the drive shaft receives a predetermined pulse signal. It is connected to a Z-axis motor (not shown) that rotates forward and backward in predetermined step units. When a drive signal corresponding to a predetermined number of steps is input to the Z-axis motor, the Z-axis motor rotates normally or reversely, and the lens moving mechanism 11 corresponds to the number of steps corresponding to the optical axis 7 direction. It moves forward or backward along.

  A plasma photodetector 12 is disposed in the lens moving mechanism 11. The plasma light detector 12 is disposed toward the plasma light emitted when the workpiece 9 is irradiated with the laser light, receives the plasma light, and detects the intensity of the plasma light. The plasma light detector 12 is provided with a filter 12a that transmits a specific wavelength so as to reduce the influence of light other than plasma light. In this embodiment, an infrared cut filter is employed to reduce the influence of light scattered by the laser light.

  An imaging device 13 is provided on an extension line of the optical axis 7 that passes through the condenser lens 8 and the dichroic mirror 6 and on the opposite side of the condenser lens 8 with respect to the dichroic mirror 6. For example, the imaging device 13 includes a coaxial incident light source (not shown) and a CCD (Charge Coupled Device). The visible light emitted from the coaxial incident light source passes through the condenser lens 8 and irradiates the work 9. The imaging device 13 can image the workpiece 9 through the condenser lens 8 and the dichroic mirror 6.

  The table unit 4 includes a base 15. On the side of the optical path portion 3 of the base 15, a rail 16 is provided so as to protrude, and an X-axis slide 17 is provided on the rail 16. The X-axis slide 17 includes a linear motion mechanism (not shown) and can move in the X direction on the rail 16. The linear motion mechanism is a mechanism similar to the linear motion mechanism included in the lens moving mechanism 11, and the X-axis slide 17 corresponds to the number of steps corresponding to the drive signal corresponding to the predetermined number of steps in the X direction. It moves forward or backward along.

  A rail 18 is provided so as to protrude from the X-axis slide 17 on the optical path section 3 side, and a Y-axis slide 19 is provided on the rail 18. The Y-axis slide 19 includes a linear motion mechanism similar to that of the X-axis slide 17 and can move on the rail 18 in the Y direction.

  A stage 20 is disposed on the optical path section 3 side of the Y-axis slide 19, and a suction chuck mechanism (not shown) is provided on the upper surface of the stage 20. When the workpiece 9 is placed, the workpiece 9 is positioned and fixed at a predetermined position on the upper surface of the stage 20 by the chuck mechanism.

The control device 5 includes a main computer 24. The main computer 24 includes a CPU (Central Processing Unit) and a memory (not shown). The CPU functions as a pass / fail judgment unit 24a that controls the operation of the laser irradiation apparatus 1 and determines the light intensity of the plasma light detected by the plasma photodetector 12 in accordance with program software stored in the memory.
The main computer 24 includes an input / output interface (not shown), and is connected to an input device 25, a display device 26, a laser control device 27, a lens control device 28, an image processing device 29, a stage control device 30, and a detector control device 31. Yes.

  The input device 25 is a device for inputting data of various processing conditions used in laser processing, and the display device 26 is a device for displaying various information at the time of laser processing. The CPU performs laser processing according to various processing conditions and program software that are input, and displays the processing status on the display device 26. The operator looks at various information displayed on the display device 26 and confirms the laser processing status for operation.

The laser control device 27 is a device that controls the pulse width of the pulse signal that drives the laser light source 2, the pulse cycle, the start and stop of output, and the like, and is controlled by the control signal of the main computer 24.
The lens control device 28 is a device that controls the movement and stop of the lens moving mechanism 11. The lens moving mechanism 11 has a built-in position sensor (not shown) that can detect the moving distance, and the lens control device 28 detects the output of the position sensor to detect the position of the condenser lens 8 in the direction of the optical axis 7. Recognize position. The lens control device 28 can transmit a pulse signal to the lens moving mechanism 11 to move the lens moving mechanism 11 to a desired position.

  The image processing device 29 has a function of calculating image data output from the imaging device 13. When the work 9 is placed on the stage 20 and an image picked up by the image pickup device 13 is observed, the image is sharpened by operating the lens moving mechanism 11 and changing the distance between the condenser lens 8 and the work 9. There are times when it is blurred. When the condenser lens 8 is moved to focus on the surface of the work 9 on the stage 20 side and when the work 9 is focused on the surface of the work 9 on the optical path unit 3 side, the image to be captured becomes clear. On the other hand, when the image is out of focus, the captured image is a blurred image.

  The thickness of the workpiece 9 is measured by moving the condenser lens 8 in the direction of the optical axis 7 and detecting the position of the condenser lens 8 at which the image picked up by the imaging device 13 becomes clear by a built-in position sensor. It becomes possible to do.

  The in-focus position is obtained by measuring the distance between the in-focus position that is in focus when imaged by the imaging device 13 and the condensing position that is condensed by the condensing lens 8 when the laser beam is irradiated. And the offset distance, which is the difference between the condensing positions. For example, an object obtained by superposing two transparent substrates is placed on the stage 20 as a work 9, and the condenser lens 8 is moved so that the imaging device 13 is focused on the contact surfaces of the two substrates. Next, the modified portion is formed by irradiating laser light. The offset distance can be measured by measuring the distance between the contact surfaces of the two substrates and the modified portion.

  The condenser lens 8 is moved in the direction of the optical axis 7, and the imaging device 13 is focused on the surface of the work 9 on the optical path portion 3 side. The moving distance of the condensing lens 8 is calculated from the position where the laser beam is to be irradiated and the offset distance, and the condensing lens 8 is moved by the same distance as the calculated moving distance. With this method, the laser beam can be condensed to a predetermined depth in the workpiece 9.

  The stage control device 30 performs acquisition of position information and movement control of the X-axis slide 17 and the Y-axis slide 19. The X-axis slide 17 and the Y-axis slide 19 have built-in position sensors (not shown), and the stage control device 30 detects the positions of the X-axis slide 17 and the Y-axis slide 19 by detecting the output of the position sensor. To detect. The stage control device 30 acquires the position information of the X-axis slide 17 and the Y-axis slide 19, compares the position information instructed from the main computer 24, and corresponds to the distance corresponding to the difference to the X-axis slide. 17 and the Y-axis slide 19 are driven to move. The stage control device 30 can drive the X-axis slide 17 and the Y-axis slide 19 to move the workpiece 9 to a desired position.

  The laser control device 27 controls the laser light source 2 to emit laser light. The image processing device 29 detects the position of the surface of the work 9 in the optical axis direction. The lens controller 28 controls the position in the optical axis direction where the laser light is condensed. The stage control device 30 moves the workpiece 9 in the XY directions, and controls the position where the workpiece 9 is irradiated with laser light. It is possible to collect and irradiate laser light at a desired position by performing the above-described control.

  The detector control device 31 receives the light intensity signal output from the plasma light detector 12 and outputs a value converted to the light intensity of the plasma light to the main computer 24. The detector control device 31 measures the light intensity signal over a predetermined time with reference to the timing signal for irradiating the laser beam from the stage 20. A noise component is removed from the light intensity signal, and the light intensity signal (peak signal) when the light intensity signal becomes strongest from the start to the end of the plasma light emission is adopted. The optical signal is output to the main computer 24.

  Here, formation of the modified portion by multiphoton absorption will be described. The laser beam condensed by the condenser lens 8 enters the workpiece 9. Even if the workpiece 9 is a material that transmits laser light, the workpiece 9 absorbs photon energy when the photon energy hν is much larger than the absorption band gap Eg of the material. This is called multiphoton absorption. When the energy is increased by making the pulse width of the laser light extremely short and the multiphoton absorption is caused inside the work 9, the energy of the multiphoton absorption is not converted into thermal energy. A region in which a permanent structural change is induced is formed.

  In the present embodiment, this structure change region is called a modified portion. Of the modified portion, a region where a plurality of cracks are formed as a result of a large structural change is called a crack portion, and a region that is formed around the crack portion and has a structure that easily absorbs laser light is called a light absorbing portion. .

  As for the irradiation condition of the laser beam for forming such a modified portion, it is necessary to set the output of the laser beam, the pulse width, the pulse period, the laser scan speed, etc. for each workpiece. In particular, it is necessary to consider that the output of the laser light emitted from the laser light source 2 is attenuated by absorption by a transmissive substance disposed on the optical axis 7 such as the dichroic mirror 6 and the condenser lens 8. Therefore, it is desirable to carry out a preliminary test using an actual workpiece to derive optimum irradiation conditions.

(Laser scribing method)
Next, the laser scribing method of the present invention will be described with reference to FIGS. FIG. 2 is a flowchart of the laser scribing method, and FIGS. 3 to 6 are diagrams for explaining the laser scribing method.

  In the flowchart of FIG. 2, step S1 corresponds to a threshold value setting step, in which the correlation between the plasma light emitted when the substrate is irradiated with laser light and the formed modified portion is examined, and the plasma light threshold value is set. It is a process. Next, the process proceeds to step S2. Step S <b> 2 corresponds to a moving process, and is a process of moving a place where the modified portion of the substrate is to be formed to a place where the laser beam is collected. Next, the process proceeds to step S3. Step S3 corresponds to a modified portion forming step, and is a step of forming a modified portion by condensing laser light in the substrate. Next, the process proceeds to step S4. Step S4 corresponds to a plasma light detection step, and is a step in which the plasma light detector 12 detects plasma light that is emitted when the modified portion is formed. Next, the process proceeds to step S5. Step S5 corresponds to a plasma light intensity determination step, and is a step of determining the light intensity of the plasma light detected by the plasma light detector 12 by comparing it with a threshold value. When the light intensity of the plasma light is less than the threshold value (NO), the process proceeds to step S3. When the light intensity of the plasma light is greater than or equal to the threshold (when YES), the process proceeds to step S6. Step S6 is a step of determining whether or not the modified portion has been formed in all the regions where the modified portion is to be formed. If there is still a region where the reforming portion is not formed in the region where the reforming portion is to be formed (NO), the process proceeds to step S2. When all the reforming portions are formed in the region where the reforming portion is to be formed (when YES), the process proceeds to step S7. Step S7 corresponds to a dividing step, and is a step of dividing the substrate along the modified portion.

Next, the manufacturing method will be described in detail using FIGS. 3 to 6 in association with the steps shown in FIG.
FIGS. 3A and 3B correspond to step S1. As shown in FIG. 3A, the modified portion 35 is formed by irradiating the inside of the substrate 34 with laser light. The substrate 34 only needs to be a light-transmitting material. In this embodiment, for example, a quartz plate is used. A crack portion 36 is formed at the center of the reforming portion 35. The form of the crack portion 36 varies depending on the material of the substrate 34, and there are cases where a plurality of cracks are formed or cavities are formed. In the present embodiment, since the quartz plate is employed for the substrate 34, the crack portion 36 becomes a cavity.

  The dimension 37 of the crack part is measured. As the dimension 37 of the crack part, which is one of the attributes of the crack part 36, the length and width of the crack part 36 and the volume obtained by calculating these can be adopted. In this embodiment, the thickness of the substrate 34 is adopted. The dimension of the method is adopted as the dimension 37 of the crack part.

The modified portion is formed by irradiating the substrate 34 with several places while changing the intensity of the laser beam. At this time, the light intensity of the emitted plasma light and the size 37 of the crack portion 36 to be formed are measured.
As shown in FIG. 3B, a correlation diagram 38 is drawn. In the correlation diagram 38, the intensity 39 of the plasma light is arranged on the horizontal axis, and the dimension 37 of the crack portion is arranged on the vertical axis. A measurement point 40 indicating the value of the measured light intensity of the plasma light and the size 37 of the crack portion to be formed is plotted in a correlation diagram 38. The approximate expression 41 is calculated from the plurality of measurement points 40 using the least square method. The intensity of plasma light corresponding to the smallest minimum dimension value 42 among the desired crack dimension 37 is calculated using the approximate expression 41. The plasma light intensity value 39a obtained by calculation is set as a threshold value.

  In consideration of the measurement error between the measured value of the intensity 39 of the plasma light and the dimension 37 of the crack portion, the threshold value may be set larger by a predetermined amount than the calculated value 39a of the intensity of the plasma light. .

4A and 4B are diagrams corresponding to step S2. 4A is a schematic cross-sectional view of the substrate, and FIG. 4B is a plan view of the substrate as viewed from the condenser lens 8 side. As shown in FIG. 4A, the condensing lens 8 is disposed at a position where the substrate 43 is arranged in the laser irradiation apparatus 1 shown in FIG. And the substrate 43 are moved relative to each other.
As shown in FIG. 4B, a surface that is to cut the substrate 43 is a cut-to-cut surface 43a. A laser beam is irradiated along the planned cutting surface 43a to advance scribing.

FIG. 4C is a diagram corresponding to step S3 and step S4. As shown in FIG. 4C, the laser beam 44 is condensed inside the substrate 43 by the condenser lens 8. A reforming portion 35 is formed at a place where the laser beam 44 is condensed, and the plasma beam 45 emits light. The plasma light 45 is detected by the plasma light detector 12, and the light intensity is measured.
As a result, as shown in FIG. 4D, the modified portion 35 is formed at the location where the laser beam 44 shown in FIG. If the light intensity of the plasma light 45 shown in FIG. 4C is higher than the threshold value in step S5, the process proceeds to step S6.

FIG. 5A corresponds to step S3. As shown in FIG. 5A, the laser beam 44 is condensed inside the substrate 43 by the condenser lens 8. When the laser beam 44 is abnormal, the modified portion 35 is not formed in the place 43b where the laser beam 44 is focused, and the emission of the plasma beam is weak. The plasma light 45 is detected by the plasma light detector 12, and the light intensity is measured.
As a result, as shown in FIG. 5B, the modified portion 35 is not formed at the location 43b where the laser beam 44 shown in FIG. In step S5, the light intensity of the plasma light detected by the plasma photodetector 12 becomes lower than the threshold value, and the process proceeds to step S3.

FIG. 5C corresponds to step S3. As shown in FIG. 5C, the laser beam 44 is condensed again at the place 43b where the modified portion 35 is not formed, the modified portion 35 is formed, and the plasma light 45 is emitted. The plasma light 45 is detected by the plasma light detector 12, and the light intensity is measured.
As a result, as shown in FIG. 5D, the modified portion 35 is formed at the location where the laser beam 44 shown in FIG. In step S5, when the light intensity of the plasma light 45 shown in FIG. 5C is higher than the threshold value, the process proceeds to step S6.

FIG. 6A is a diagram corresponding to step S6. As shown in FIG. 6A, the substrate 43 and the condensing lens 8 shown in FIG. 5D are relatively moved, and the modified portions 35 are arranged on the planned cutting surface 43a. As a result, the reforming part 35 is formed over the entire cut surface 43a of the substrate 43.
As shown in FIG. 6B, since the crack portion 36 is formed in the center of the modified portion 35 shown in FIG. 6A, the crack portion 36 extends over the entire cut surface 43a of the substrate 43. Are arranged.

FIG. 6C is a diagram corresponding to step S7. As shown in FIG. 6C, the substrate 43 is placed on an elastic base 46. A pressurizing member 47 is arranged at a position on the substrate 43 corresponding to the crack portion 36 formed by being arranged inside the substrate 43, and the pressurizing member 47 is pressed in the direction of the substrate 43. In the substrate 43, the place pressed by the pressing member 47 sinks into the table 46, and a tension acts on the surface in contact with the table 46. The crack portion 36 is tensioned, and breakage proceeds and is divided from the crack as a starting point.
As a result, as shown in FIG. 6D, the substrate 43 is divided at the crack portion 36 and divided into two.

As described above, this embodiment has the following effects.
(1) According to the present embodiment, the laser irradiation apparatus 1 includes the plasma light detector 12 and detects the light intensity of the plasma light 45 emitted from the modified portion 35 formed by condensing the laser light 44. is doing. Thereby, the formation status of the reforming part 35 can be confirmed.

  (2) According to the present embodiment, the intensity of the plasma light 45 emitted from the reforming unit 35 is detected, and the light intensity of the plasma light 45 is compared with a threshold value to determine whether the reforming unit 35 is formed. When it is determined that the formed modified portion 35 is defective, the modified portion 35 is formed by condensing the laser beam 44 again at the place where the defect has occurred. Therefore, it is possible to perform scribing with few defects in the reforming portion 35.

  (3) According to the present embodiment, each time the reforming portion 35 is formed, the light intensity of the plasma light 45 is compared with a threshold value, and if it is defective, the reforming portion 35 is formed again at that time. is doing. It is manufactured by directly connecting defect detection and defective part reproduction. Therefore, it is easier to control the laser irradiation apparatus 1 than the method of continuously forming the reforming portion 35 while storing the defective portion, and regenerating the defective portion after processing the planned scribe region. Can be manufactured.

  (4) According to this embodiment, the plasma photodetector 12 is provided with the filter 12a that transmits a specific wavelength. Therefore, the influence of light other than plasma light is reduced, and the light intensity of plasma light is measured with high accuracy.

  (5) According to the present embodiment, the plasma light detector 12 detects the light intensity emitted from the place where the laser light is condensed by the lens support portion 10. Therefore, even if the workpiece 9 moves, the plasma light detector 12 can detect the plasma light.

  (6) According to the present embodiment, the relative position of the plasma photodetector 12 with respect to the condenser lens 8 is fixed by the lens support portion 10. Therefore, the relative position with respect to the place where the laser beam 44 is condensed by the condenser lens 8 is fixed. Accordingly, the distance between the condensing lens 8 and the condensing lens 8 is fixed, and when the workpiece 9 is moved, the distance between the condensing lens 8 and the condensing lens 8 is not changed. It is like that. The plasma light 45 emitted from the place where the laser light 44 is collected is in the form of a point light source, and the light intensity decreases as the distance from the place where the laser light 44 is collected. In the present embodiment, since the distance between the condensing lens 8 and the location where the laser light 44 is condensed does not change, the influence of the distance between the light source of the plasma light 45 and the plasma photodetector 12 can be reduced. it can.

  (7) According to this embodiment, the plasma photodetector 12 is disposed on the condenser lens 8 side with respect to the workpiece 9. When the modified portions 35 are arranged and formed on the planned cutting surface 43 a, the modified portions 35 are formed from the side opposite to the condenser lens 8 in the work 9. Therefore, there is no reformed portion 35 already formed between the place where the laser beam 44 is collected and the plasma photodetector 12. The plasma light 45 emitted from the place where the laser light 44 is collected is not scattered by the modified portion 35 already formed and is not easily affected. As a result, the light intensity of the plasma light 45 can be accurately measured.

(Second Embodiment)
Next, a schematic diagram showing the configuration of the laser irradiation apparatus in FIG. 7, a flowchart in FIGS. 8 and 9 and a laser scribing method in FIGS. 10 and 11 for the laser scribing method according to the second embodiment of the present invention will be described. This will be described with reference to the drawings.
In the present embodiment, the same members or parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
This embodiment is different from the first embodiment in that the laser irradiation apparatus 1 includes a defective position storage device and performs a process of forming a modified portion, and then, the modified portion is scribed again at a location where the defective portion is formed. The process to perform is in that.

  As shown in FIG. 7, the laser irradiation device 49 includes a defective position storage device 50, and the defective position storage device 50 is connected to the main computer 24. The workpiece 9 is irradiated with laser light, and the plasma light detector 12 detects the emitted plasma light. The plasma light detector 12 outputs a light intensity signal to the detector control device 31. The detector control device 31 outputs the light intensity of the plasma light to the main computer 24. The pass / fail judgment unit 24a of the main computer 24 judges pass / fail by comparing the light intensity of the plasma light with a threshold value. When the quality is judged to be defective, the position information of the X-axis slide 17 and the Y-axis slide 19 is acquired from the stage control device 30, and the position information of the condenser lens 8 is acquired from the lens control device 28 to obtain the defective position. It is recorded in the storage device 50.

  In the flowchart of FIG. 8, step S10 corresponds to a threshold value setting step, in which the correlation between the plasma light emitted when the substrate is irradiated with laser light and the modified portion to be formed is examined, and the plasma light threshold value is set. It is a process. Next, the process proceeds to step S11. Step S11 corresponds to a moving step, and is a step of moving the place where the laser beam is focused to a place where the modified portion of the substrate is to be formed. Next, the process proceeds to step S12. Step S12 corresponds to a modified portion forming step, and is a step in which the modified portion is formed by condensing the laser beam in the substrate. Next, the process proceeds to step S13. Step S13 corresponds to a plasma light detection step, and is a step in which the plasma light detector 12 detects plasma light that is emitted when the modified portion is formed. Next, the process proceeds to step S14. Step S14 corresponds to a plasma light intensity determination step, and is a step of determining pass / fail by comparing the light intensity of the plasma light detected by the plasma light detector 12 with a threshold value. When the light intensity of the plasma light is less than the threshold value (NO), the process proceeds to step S15. When the light intensity of the plasma light is equal to or higher than the threshold (when YES), the process proceeds to step S16. Step S15 corresponds to a defective place storage step, and is a step of storing a place where the light intensity of the plasma light is less than a threshold (hereinafter referred to as a defective place). Step S16 is a step of determining whether or not the reforming portion has been formed in all regions where the reforming portion is to be formed at the stage where the reforming portion is formed. If there is still a region where the reforming portion is not formed in the region where the reforming portion is to be formed (NO), the process proceeds to step S11. When all the reforming parts are formed in the area where the reforming part is to be formed (YES), the process proceeds to step S17. Step S17 is a step of determining whether there is a defective place at the stage where the reforming portion is formed. If there is no defective place (NO), the process proceeds to step S19. If there is a defective place (YES), the process proceeds to step S18. Step S18 corresponds to a re-scribing process of the defective place, and is a process of scribing again to the place where the light intensity of the plasma light is determined to be less than the threshold value in step S14. Next, the process proceeds to step S19. Step S19 is a step of determining whether or not the modified portion has been formed in all the regions where the modified portion is to be formed. If there is still a region where the reforming portion is not formed in the region where the reforming portion is to be formed (NO), the process proceeds to step S11. When all the reforming parts are formed in the region where the reforming part is to be formed (YES), the process proceeds to step S20. Step S20 corresponds to a dividing step, and is a step of dividing the substrate along the modified portion.

  In the flowchart of FIG. 9, the step of re-scribing the defective place in step S18 will be described in detail. Step S21 corresponds to a moving process, and in step S14, the place where the light intensity of the plasma light is less than the threshold is moved to a place where laser light can be irradiated. Next, the process proceeds to step S22. Step S22 corresponds to a modified portion forming step, and is a step of forming a modified portion by condensing laser light in the substrate. Next, the process proceeds to step S23. Step S23 corresponds to a plasma light detection step, and is a step in which the plasma light detector 12 detects plasma light that is emitted when the modified portion is formed. Next, the process proceeds to step S24. Step S24 corresponds to a plasma light intensity determination step, and is a step of determining the light intensity of the plasma light detected by the plasma light detector 12 by comparing it with a threshold value. When the light intensity of the plasma light is less than the threshold value (NO), the process proceeds to step S22. When the light intensity of the plasma light is greater than or equal to the threshold value (when YES), the process proceeds to step S25. Step S25 is a step of determining whether or not the reforming portion has been formed in all defective places at the stage where the reforming portion is formed. The determination is made by comparing the defective location stored in the defective location storage device 50 with the location where the reforming portion is formed again. If there is still a region where the reforming portion is not formed at the defective location (NO), the process proceeds to step S21. When all the reforming parts are formed in the defective place (when YES), step S18 is ended.

Next, the manufacturing method will be described in detail with reference to FIGS. 10 to 11 in association with the steps shown in FIGS. Note that the description of the same steps as those in the first embodiment will be omitted.
FIG. 10A is a diagram corresponding to step S12 and step S13. As shown in FIG. 10A, the substrate 43 is placed on the stage 20 of the laser irradiation device 49, and the laser light 44 is condensed inside the substrate 43 by the condenser lens 8. When the light intensity of the laser light 44 is weak, the normal modified portion 35 is not formed at the place where the laser light 44 is collected, and the emitted plasma light 45 has a low light intensity. The plasma light 45 is detected by the plasma light detector 12, and the light intensity is measured. The measured light intensity is compared with a threshold value by the pass / fail judgment unit 24a of the main computer 24 shown in FIG. 7, and when the light intensity is weaker than the threshold value, the position coordinate information of the defective place 51 is stored in the defective position storage device 50. Remembered.
As a result, as shown in FIG. 10B, the normal reforming portion 35 is not formed in the defective place 51.

  FIG.10 (c) is a figure corresponding to step S12 and step S13 after determining with NO by step S16 and passing through step S11. As shown in FIG. 10C, the laser beam 44 is condensed inside the substrate 43 by the condenser lens 8 at a place adjacent to the defective place 51. A reforming portion 35 is formed at a place where the laser beam 44 is condensed, and the plasma beam 45 emits light. The plasma light 45 is detected by the plasma light detector 12, and the light intensity is measured.

When the light intensity detected by the plasma light detector 12 is higher than the threshold, the process proceeds to the next step without being stored in the defective position storage device 50 shown in FIG.
As a result, as shown in FIG. 10D, in the stage where the reforming portion 35 is formed, the formed reforming portion 35 and the defective location 51 are mixed, and the defective location 51 is the failure shown in FIG. The state is stored in the position storage device 50. When YES is determined in the step S17, the process proceeds to a step S21.

  FIG. 11A is a diagram corresponding to step S21. The condensing lens 8 is moved to a position where the laser beam can be condensed at the defective location 51 with reference to the information on the defective location stored in the defective location storage device 50 shown in FIG.

FIG. 11B is a diagram corresponding to step S22 and step S23. The laser beam 44 is condensed inside the substrate 43 by the condenser lens 8. A reforming portion 35 is formed at a place where the laser beam 44 is condensed, and the plasma beam 45 emits light. The plasma light 45 is detected by the plasma light detector 12, and the light intensity is measured.
As a result, as shown in FIG. 11C, the normal reforming part 35 is formed in the defective place 51, and the reforming part 35 is formed in all the stages forming the reforming part 35.

  FIG. 11D is a diagram corresponding to step S19. As shown in FIG. 11 (d), the modified portions 35 are arranged in the thickness direction of the substrate 43. As a result, the reforming portion 35 is formed over the entire planned cutting surface 43a shown in FIG.

As described above, according to the present embodiment, in addition to the effects (1), (2), and (4) to (7) of the first embodiment, the following effects are obtained.
(1) According to the present embodiment, when the light intensity of the plasma light 45 emitted when the laser beam 44 is condensed inside the substrate 43 is weak, the location is stored as the defective location 51 in the defective location storage device 50. And continue to scribe. Compared with the method of stopping the stage 20 and condensing the laser beam 44 when the light intensity of the plasma light 45 is weak, it takes less time to stop and start the stage 20, and thus scribe with high productivity. be able to.

(Third embodiment)
Next, a laser scribing apparatus according to a third embodiment of the present invention will be described with reference to the schematic diagram showing the configuration of the laser irradiation apparatus of FIG.
In the present embodiment, the same members or parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
This embodiment is different from the first embodiment in that the plasma photodetector is disposed on the opposite side of the condenser lens with respect to the workpiece.

  As shown in FIG. 12, the laser irradiation device 54 includes a plasma light detector 56 via a support portion 55 disposed on the base 15. On the base 15, a rail 16, an X-axis slide 17, a rail 18, a Y-axis slide 19, and a stage 57 are arranged in this order. The stage 57 has a hollow interior, and a plasma photodetector 56 is disposed inside the stage 57. A workpiece 9 is disposed on the stage 57, and the workpiece 9 is irradiated with the laser beam condensed from the condenser lens 8 of the optical path unit 3.

  The optical axis 7 through which the laser beam of the optical path unit 3 passes is disposed so as to pass through the workpiece 9 and the plasma photodetector 56. When the optical path unit 3 and the workpiece 9 move relative to each other, the optical axis 7 Passes through the plasma photodetector 56.

As described above, according to the present embodiment, in addition to the effects (1) to (4) of the first embodiment, the following effects are obtained.
(1) According to the present embodiment, the plasma photodetector 56 is disposed at a location that passes through the optical axis 7 on the opposite side of the optical path portion 3 with respect to the workpiece 9. When the laser light focused on the condenser lens 8 forms a modified portion in the workpiece 9 and emits plasma light, the plasma light irradiates the plasma photodetector 56. The energy of the laser beam increases on the optical axis 7, and the light intensity of the plasma light also increases on the optical axis 7. Therefore, the plasma light detector 56 can receive light having a stronger light intensity when it is disposed near the optical axis 7 than when it is disposed far from the optical axis 7. Accordingly, the laser irradiation device 54 can be a device that is easily located at a position where the plasma light detector 56 easily receives the plasma light, and can easily detect the plasma light.

  In addition, this invention is not limited to embodiment mentioned above, A various change and improvement can also be added. A modification will be described below.

(Modification 1)
In the first embodiment and the second embodiment, the condensing lens 8 and the substrate 43 are relatively moved in the direction of the X-axis slide 17 or the Y-axis slide 19 to form the reforming unit 35 to form one stage. After the reforming portions 35 are arranged, the steps of the reforming portions 35 are formed in an overlapping manner, but the present invention is not limited to this. As shown in FIG. 13, the substrate 43 and the condenser lens 8 are relatively moved in the thickness direction of the substrate 43 to form a row of the reforming portions 35, and the rows of the reforming portions 35 are sequentially arranged to form the reforming portion. 35 may be arranged.
When the substrate 43 has different characteristics in the plane direction and it is necessary to change the laser beam conditions, the predetermined region can be continuously processed under the same laser beam irradiation conditions, so that the substrate 43 can be processed with high productivity.

(Modification 2)
In step S3 to step S5 of the first embodiment, when the light intensity of the plasma light is weak, the flow is repeated many times. However, when the number of repetitions is set and the number of repetitions reaches the set number of times, the flow is interrupted. Then, the operator may confirm the situation.

(Modification 3)
In step S22 to step S24 of the second embodiment, the flow is repeated many times when the light intensity of the plasma light is weak. However, when the number of repetitions is set and the number of repetitions reaches the set number of times, the process is interrupted. Then, the operator may confirm the situation.

Schematic which shows the structure of the laser irradiation apparatus which concerns on 1st Embodiment. The flowchart of a laser scribe method. The figure explaining the laser scribing method. The figure explaining the laser scribing method. The figure explaining the laser scribing method. The figure explaining the laser scribing method. Schematic which shows the structure of the laser irradiation apparatus which concerns on 2nd Embodiment. The flowchart of a laser scribe method. The flowchart of a laser scribe method. The figure explaining the laser scribing method. The figure explaining the laser scribing method. Schematic which shows the structure of the laser irradiation apparatus which concerns on 3rd Embodiment. The figure explaining the laser scribing method which concerns on a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Laser light source, 8 ... Condensing lens as a condensing part, 12a ... Filter, 12 ... Plasma light detector, 24a ... Pass / fail judgment part, 34, 43 ... Substrate, 35 ... Modification part, 44 ... Laser light, 45 ... Plasma light.

Claims (8)

A scribing method for scribing by irradiating a substrate that transmits visible light with laser light,
Detecting the plasma light emitted when the modified portion is formed by condensing the laser light inside the substrate;
A scribing method, wherein the quality of the modified portion is judged based on the light intensity of the plasma light to be detected. The scribing method according to claim 1,
From the correlation between the light intensity of the plasma light and the dimensions of the modified portion, a threshold value of the light intensity is provided,
When scribing to the substrate, when the light intensity of the generated plasma light is weaker than the threshold value, the laser beam is condensed again at the same place to form the modified portion. The scribing method according to claim 2,
Moving the place where the laser beam is sequentially focused on the substrate to form the modified portion;
When the plasma light when forming the modified portion is weaker than the threshold,
Without moving the place where the modified portion is formed on the substrate,
Condensing the laser light again at a place where the plasma light is weaker than the threshold value to form the modified portion,
After forming the modified portion, the array of the modified portions is formed by repeatedly moving the place where the laser beam is focused on the substrate to form the modified portion. Scribe method. The scribing method according to claim 2,
Moving the place where the laser beam is sequentially focused on the substrate to form the modified portion;
Storing the place where the plasma light when forming the modified portion is weaker than the threshold;
The scribing method, wherein the modified portion is formed by condensing the laser beam again at the stored location. A scribing device for scribing a substrate by irradiating a laser beam,
A laser light source for emitting the laser light;
A condensing part for condensing a laser beam inside the substrate to form a modified part;
A plasma photodetector for detecting plasma light emitted when the modified portion is formed;
A scribing apparatus comprising a pass / fail judgment unit for judging pass / fail of the reforming unit based on the light intensity of the plasma light detected by the plasma photodetector. The scribing device according to claim 5,
A scribing apparatus, wherein a filter that transmits a specific wavelength is installed in the plasma detector. The scribing device according to claim 5 or 6,
The scribing apparatus, wherein the plasma detector is disposed so that a place for condensing the laser light is within a range in which the plasma light can be detected. A scribing device according to claim 7,
The scribing apparatus, wherein a distance between the laser beam condensing place and the plasma detector is maintained at substantially the same distance.

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