JP2008174395A - Dividing method of substrate and manufacturing method of electro-optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dividing method of a substrate which can divide a substrate having optical elements at a given position, and a manufacturing method of an electro-optical device equipped with the substrate. <P>SOLUTION: The inventive dividing method of a substrate is provided with a measuring step for measuring the position of a micro-lens 3 that is positioned on a predetermined line for cutting on a mother substrate W2 as the substrate, a calculating step for finding the irradiation interval of laser light 113 to the micro-lens 3 on the basis of the measured result, an irradiating step for irradiating the laser light 113 on the mother substrate W2 on the basis of the calculated result, and a dividing step for dividing the mother substrate W2 irradiated with the laser light 113. In the irradiating step, the laser light 113 is irradiated at a given interval Lm so as to make a condensing point agree with the inside of the micro-lens 3, to generate a multiphoton absorption at the condensing point, and to form reformed areas 21. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for dividing a substrate that transmits laser light and a method for manufacturing an electro-optical device including the substrate.

  As a method for dividing a substrate that transmits laser light, there is known a laser processing method that can cut a workpiece without causing melting or cracks that are off the planned cutting line on the surface of the workpiece (patent) Reference 1).

  In the above laser processing method, a laser beam is irradiated while focusing on the inside of the processing object, and a modified region by multiphoton absorption is formed inside the processing object along a planned cutting line. The object to be processed is divided along the scheduled cutting line with this modified region as a starting point.

  As an electro-optical device including a substrate that transmits laser light, a display device (liquid crystal projector) including a light source and a micro lens array (MLA) that collects light incident from the light source is known (patent). Reference 2). Moreover, the manufacturing method of the organic electroluminescent element (organic EL element) as a device provided with the micro lens is known (patent document 3).

JP 2002-192370 A JP 2000-75106 A JP 2006-23683 A

  It is conceivable to apply the laser processing method as a method for dividing a substrate provided with the microlens described in Patent Document 2 or Patent Document 3. However, when the laser beam is irradiated onto the substrate on which the microlens is formed, the laser beam is refracted by the microlens, and the position of the condensing point is not determined inside the substrate, and the substrate as the processing object is cut along the planned cutting line. There was a problem that it was not possible to break.

  The present invention has been made to improve the above problems, and provides a method for dividing a substrate that can divide a substrate having an optical element at a predetermined position, and a method for manufacturing an electro-optical device including the substrate. Objective.

  The substrate dividing method of the present invention is a method for dividing a substrate that is capable of transmitting laser light and has at least one optical element at a position along a line to be cut, and is based on position information of the optical element on the substrate. The calculation step for obtaining the laser beam irradiation interval in the direction along the planned cutting line and the scanning for moving the laser beam relatively along the planned cutting line are performed a plurality of times while changing the position of the condensing point inside the substrate. And an irradiation step of irradiating so that multiphoton absorption occurs at the condensing point, and a dividing step of dividing the substrate irradiated with the laser beam. In the irradiation step, the condensing point is provided inside the optical element. And at least one scan is performed in which the laser beam is irradiated at the irradiation interval.

  When irradiating an optical element with laser light, the focal point is not necessarily located on the optical axis of the laser light at the time of incidence depending on the irradiation position. According to this method, the irradiation interval of the laser light in the direction along the scheduled cutting line is obtained based on the position information of the optical element on the substrate in the calculation step. In the irradiation step, a condensing point is positioned inside the optical element, and at least one scan is performed to irradiate the laser beam with the irradiation interval obtained in the calculation step. Therefore, the irradiation position of the laser beam on the optical element becomes constant, and multiphoton absorption at the condensing point can be generated at a constant position along the planned cutting line inside the optical element. Therefore, the substrate can be accurately divided along the planned cutting line, starting from the modified layer formed by multiphoton absorption.

  A measurement step of measuring the position of the optical element by irradiating the substrate with reference light may be further provided, and the calculation step may determine the irradiation interval based on the position information of the optical element obtained in the measurement step. According to this, the position of the optical element on the substrate is actually measured in the measurement process, and the laser light irradiation interval is obtained based on the actual measurement. Therefore, the laser beam irradiation interval can be accurately obtained regardless of how the optical elements are arranged on the planned cutting line. Therefore, the substrate can be divided with high accuracy.

  Further, in the calculation step, the position of the optical axis of the optical element in the direction along the planned cutting line is obtained based on the position information of the optical element, and in the irradiation step, a condensing point is set on the optical axis inside the optical element. It is preferable to perform scanning that is positioned and irradiated with laser light. According to this, the optical axis of the optical element matches the optical axis of the laser beam. Therefore, compared with the case where the optical axis of the optical element and the optical axis of the laser beam are shifted, the incident angle of the laser beam to the optical element is constant, and the modified layer by multiphoton absorption is stabilized on the optical axis of the laser beam. Can be formed. Therefore, the substrate can be divided with higher accuracy.

  Further, the optical element is periodically provided along the line to be cut, and in the irradiation step, the irradiation interval for irradiating the optical element with the laser light is the same as the optical element period or an integral multiple of the period. It is characterized by being. According to this, the laser light is irradiated in synchronization with the period of the optical element or at an irradiation interval of an integral multiple. Therefore, the modified layer by multiphoton absorption can be formed at a position along the planned cutting line inside the optical element to such an extent that the substrate can be divided.

  Further, in the irradiation step, the irradiation interval may be set by setting a relative moving speed between the laser beam and the substrate constant and controlling opening / closing of a shutter that blocks the laser beam. According to this, an appropriate irradiation interval can be set by controlling the opening and closing of the shutter in accordance with the arrangement of the optical elements regardless of the type of laser light.

  Pulse laser light is used as the laser light, and the repetition rate of the pulse laser light is set so that the relative movement speed between the pulse laser light and the substrate is constant and the irradiation interval is the same as the period of the optical element in the irradiation process. It is good. According to this, even if the period of the optical element becomes fine, the irradiation interval of the laser light can be accurately handled.

  These inventions can be applied to a method for dividing a substrate provided with a microlens or a prism as an optical element.

  A method for manufacturing an electro-optical device according to the present invention is a method for manufacturing an electro-optical device that includes a substrate that is capable of transmitting laser light and has at least one optical element at an outer position. A method is used to divide the substrate from the mother substrate by irradiating laser light along a planned cutting line of the mother substrate.

  According to this method, it is possible to divide a substrate having an optical element from a mother substrate with high dimensional accuracy, and to reduce an external defect caused by the division, thereby manufacturing an electro-optical device with a high yield.

  In the present embodiment, a method for manufacturing a liquid crystal display device as an electro-optical device provided in a projection display device as an electronic apparatus will be described as an example.

  First, the projection display device will be briefly described. FIG. 1 is a schematic diagram illustrating a configuration of a projection display device.

  As shown in FIG. 1, the projection display device 200 includes a light source 210, two dichroic mirrors 213 and 214, three reflection mirrors 215, 216, and 217, an incident lens 218, a relay lens 219, and an exit lens. 220, three liquid crystal light modulators 222, 223, and 224, a cross dichroic prism 225, and a projection lens 226. The light source 210 includes a lamp 211 such as a metal halide, and a reflector 212 that reflects light from the lamp 211. The dichroic mirror 213 transmits red light out of the light flux from the light source 210 and reflects blue light and green light. The transmitted red light is reflected by the reflection mirror 217 and enters the liquid crystal light modulator 222 for red light. On the other hand, of the light reflected by the dichroic mirror 213, the green light is reflected by the dichroic mirror 214 and enters the liquid crystal light modulator 223 for green light. Of the light reflected by the dichroic mirror 213, the blue light also passes through the dichroic mirror 214. For blue light, in order to prevent light loss due to a long optical path, a light guide mechanism 221 including a relay lens system including an incident lens 218, a relay lens 219, and an output lens 220 is provided. The light enters the liquid crystal light modulator 224 for light. The three color lights modulated by the liquid crystal light modulators 222, 223, and 224 are incident on the cross dichroic prism 225. In the cross dichroic prism 225, four right-angle prisms are bonded, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in a cross shape on the inner surface thereof. Three color lights are synthesized by these dielectric multilayer films. Then, a color image composed of the combined light is projected onto the screen 227 by the projection lens 226 which is a projection optical system, and is enlarged and displayed.

  Each of the liquid crystal light modulators 222, 223, and 224 is called a light valve, and is a liquid crystal display device to be described later, and a polarizing plate as a polarizing element (illustrated) respectively disposed on the light incident side and the light exit side of the liquid crystal display device. (Omitted).

  Next, a liquid crystal display device will be described. FIG. 2 is a schematic cross-sectional view showing the structure of the liquid crystal display device.

  As shown in FIG. 2, the liquid crystal display device 20 includes a counter substrate 1 and an element substrate 7 as a pair of substrates, and a liquid crystal 9 sandwiched between the counter substrate 1 and the element substrate 7.

  The counter substrate 1 includes a glass substrate 2 made of transparent quartz glass, a hemispherical microlens 3 as an optical element formed on the glass substrate 2, and a transparent laminated layer covering the plurality of microlenses 3. And a resin layer 4. On the surface of the transparent resin layer 4, the counter electrode 5 and the alignment film 6 are formed in a predetermined range facing the liquid crystal 9. The glass substrate 2 is not limited to quartz glass as long as it is a material that transmits light, and may be a transparent resin substrate.

  The plurality of microlenses 3 are arranged on the surface of the glass substrate 2 at a predetermined interval. A light shielding film 13 is formed so as to fill the space between the arranged microlenses 3. The light shielding film 13 may be, for example, a metal thin film such as Cr or a resin film containing a light shielding pigment. A group of the microlenses 3 is referred to as an MLA (microlens array).

  For example, as disclosed in Japanese Patent Application Laid-Open No. 2000-75106, such an MLA formation method is performed by coating a photosensitive resin containing a photopolymer on a light-shielding film 13 having an opening, and performing photolithography to form a pixel. Part 10 is formed. After that, the pixel part 10 is melted (softened) by the heating process to obtain the microlens 3 having a convex surface. Alternatively, an ultraviolet curable resin containing a photopolymer is discharged as droplets toward the opening of the light shielding film 13. And the method of making it the micro lens 3 by irradiating and hardening | curing an ultraviolet-ray in the state which raised by surface tension is mentioned.

  In this case, the microlenses 3 are arranged in a matrix and constitute the pixel unit 10. The size is about 100 μm in diameter and about 50 μm in height.

  For the transparent resin layer 4 covering the MLA, for example, an ultraviolet curable acrylic resin can be used. Examples of the method for forming the transparent resin layer 4 include spin coating and roll coating. The thickness is approximately 50-100 μm.

  As the counter electrode 5, for example, a transparent electrode made of ITO (Indium Tin Oxide) formed by a method such as sputtering can be used.

  The element substrate 7 uses a quartz glass substrate similarly to the counter substrate 1, and has a pixel electrode 11 provided on the surface thereof facing the pixel portion 10 of the counter substrate 1, and a thin film transistor 12 provided for each pixel electrode 11. have. An alignment film 8 is provided so as to cover the pixel electrode 11 and the thin film transistor 12. The element substrate 7 is not limited to quartz glass as long as it is a material that transmits light, and may be a transparent resin substrate.

  The light emitted from the light source 210 in FIG. 1 enters from the glass substrate 2 side through the above-described optical system, is collected by the microlens 3, and passes through the opposing pixel electrode 11. As a result, the liquid crystal display device 20 capable of displaying a bright screen by efficiently using incident light is realized.

<Method for manufacturing liquid crystal display device>
Next, a method for manufacturing a liquid crystal display device as an electro-optical device according to this embodiment will be described. 3A and 3B are schematic views showing a mother substrate. FIG. 4A is a schematic plan view, and FIG. 4B is a schematic cross-sectional view taken along line AA in FIG.

  As shown in FIGS. 3A and 3B, in the method of manufacturing the liquid crystal display device 20, first, a mother substrate W1 in which a plurality of components of the element substrate 7 corresponding to one liquid crystal display device 20 are formed in a matrix. In addition, a sealing material is applied at a predetermined position corresponding to each liquid crystal display device 20. Examples of the application method include a printing method, a transfer method, and a dispensing method. The liquid crystal 9 is filled inside the sealing material, and the counter substrate 1 is bonded to a position corresponding to each liquid crystal display device 20 under reduced pressure. The plurality of liquid crystal display devices 20 are taken out by cutting the cutting marks Sx and Sy in the X-axis and Y-axis directions by a method such as dicing or scribing.

  FIG. 4 is a schematic plan view showing the mother substrate on the counter substrate side. As shown in FIG. 4, the mother substrate W2 is formed with a plurality of components of the counter substrate 1 in a matrix. Each counter substrate 1 was divided by irradiating laser light along the planned cutting lines Dx and Dy of the mother substrate W2. The microlens 3 is formed over almost the entire surface of the mother substrate W2. Therefore, the microlenses 3 periodically exist on the scheduled cutting lines Dx and Dy.

<Division method of substrate>
Next, a method for dividing the mother substrate W2 as the substrate of this embodiment will be described with reference to FIGS. First, the laser irradiation apparatus used in this embodiment and the principle of laser processing will be described.

  FIG. 5 is a schematic diagram showing the configuration of the laser irradiation apparatus. As shown in FIG. 5, the laser irradiation apparatus 100 includes a laser light source 101 that emits laser light, a dichroic mirror 102 that reflects the emitted laser light, and a collection unit that collects the reflected laser light. And an optical lens 103. Further, the stage 105 on which the substrate W as a processing target is placed, and a moving means that can move the stage 105 relative to the condenser lens 103 in a plane substantially orthogonal to the optical axis 101a of the laser beam. An X-axis slide unit 108 and a Y-axis slide unit 106 are provided. Also, a Z-axis slide as a moving means that can move the condensing lens 103 relative to the substrate W placed on the stage 105 to change the position of the condensing point of the laser light in the thickness direction of the substrate W. A mechanism 104 is provided. Furthermore, an imaging mechanism 110 is provided that is located on the opposite side of the condenser lens 103 with the dichroic mirror 102 interposed therebetween. Between the laser light source 101 and the dichroic mirror 102, a shutter 111 that shields the laser light is provided. The opening and closing of the shutter 111 is controlled by the laser control unit 121.

  The laser irradiation apparatus 100 includes a main computer 120 as a control unit that controls each of the above components. In addition to the CPU and various memories, the main computer 120 includes an image processing unit 124 that processes image information captured by the imaging mechanism 110. The imaging mechanism 110 incorporates a coaxial incident light source and a CCD (solid-state imaging device). Visible light as reference light emitted from the coaxial incident light source passes through the condenser lens 103 and is focused. As the coaxial incident light source, for example, a semiconductor laser having substantially the same wavelength as the laser light emitted from the laser light source 101 can be used. This makes it possible to set the irradiation position under conditions close to actual laser irradiation.

  The main computer 120 is connected to an input unit 125 for inputting data of various processing conditions used during laser processing and a display unit 126 for displaying various information during laser processing. The laser control unit 121 controls the output of the laser light source 101, the pulse width and the pulse period of the laser beam, and the lens control unit controls the position of the condenser lens 103 in the Z-axis direction by driving the Z-axis slide mechanism 104. 122 is connected. Further, a stage control unit 123 is connected to drive a servo motor (not shown) that moves the X-axis slide unit 108 and the Y-axis slide unit 106 along the rails 107 and 109, respectively.

  The Z-axis slide mechanism 104 that moves the condensing lens 103 in the Z-axis direction has a built-in position sensor capable of detecting the moving distance, and the lens control unit 122 detects the output of the position sensor and collects the light. The position of the lens 103 in the Z-axis direction can be controlled. Therefore, the thickness of the substrate W can be measured by moving the condenser lens 103 in the Z-axis direction so that the focus of the visible light emitted from the coaxial incident light source of the imaging mechanism 110 is aligned with the surface of the substrate W. It is. In other words, it is possible to detect the movement distance when the focus of visible light is moved in the Z-axis direction.

  The laser light source 101 is a so-called femtosecond laser that emits laser light having, for example, titanium sapphire as a solid light source with a femtosecond pulse width. In this case, the laser beam has wavelength dispersion characteristics, the center wavelength is 800 nm, and the half width is about 10 nm. The pulse width is about 300 fs (femtosecond), the output is about 700 mW, and the pulse period as a repetition rate can be varied from 1 to 10 kHz.

  In this case, the condensing lens 103 is an objective lens having a magnification of 100 times, a numerical aperture (NA) of 0.8, and a WD (Working Distance) of 3 mm. The condenser lens 103 is supported by a slide arm 104 a extending from the Z-axis slide mechanism 104.

  In this embodiment, the stage 105 is supported by the Y-axis slide unit 106, but is supported by the X-axis slide unit 108 by reversing the positional relationship between the X-axis slide unit 108 and the Y-axis slide unit 106. It is good also as a form. Further, it is preferable to support the stage 105 on the Y-axis slide unit 106 via a θ table. According to this, it is possible to make the substrate W more perpendicular to the optical axis 101a.

  6A and 6B are schematic cross-sectional views showing a state in which the position of the laser light condensing region is varied in the thickness direction of the workpiece. FIG. 6A is a schematic cross-sectional view showing a state in which the end of the laser light condensing region is positioned so as to be on the surface Wb opposite to the laser light incident surface Wa, and FIG. It is a schematic sectional drawing which shows the state from which the condensing area | region gradually approached the entrance plane Wa.

  As shown in FIG. 6A, since the laser beam 113 collected by the condenser lens 103 has a wavelength dispersion characteristic, the substrate W (quartz glass portion) having a refractive index of about 1.46 is used. The condensing point from the short-wavelength laser beam 114 to the long-wavelength laser beam 115 is condensed on a condensing region 116 shifted on the optical axis 101a. The condensing region 116 has a so-called axial chromatic aberration. In this case, since the condensing point of the laser light 115 on the long wavelength side of the condensing region 116 is close to the surface Wb, the optical path difference between the laser light 114 on the short wavelength side and the laser light 115 on the long wavelength side is the largest. It is getting bigger. That is, the width of the light collection region 116 in the thickness direction of the substrate W is the maximum.

  As shown in FIG. 6B, when the Z-axis slide mechanism 104 is driven to move the condensing lens 103 in the Z-axis direction so that the position of the condensing region 116 approaches the incident surface Wa side, The optical path difference between the laser light 114 on the short wavelength side and the laser light 115 on the long wavelength side is gradually reduced. Accordingly, the width of the substrate W in the thickness direction gradually changes from the condensing region 117 where the width is gradually reduced to the condensing region 118. Of course, when the Z-axis slide mechanism 104 is driven so that the condensing region approaches the surface Wb from the vicinity of the incident surface Wa and the condensing lens 103 is moved in the Z-axis direction, the condensing region 118 collects light. The width in the thickness direction of the substrate W gradually increases toward the region 116.

  If the laser light source 101 has a small wavelength dispersion characteristic, that is, a half-width is very narrow and the chromatic aberration of the condensing lens 103 is small or corrected, the laser light source 101 depends on the position of the condensing point in the thickness direction of the substrate W. It is possible to suppress the amount of change in which the width of the light collection region changes.

  Here, the formation of the modified region by multiphoton absorption will be described. Even if the object to be processed is a transparent material, absorption occurs when the photon energy hν is much larger than the absorption band gap Eg of the material. This is called multiphoton absorption. When the pulse width of the laser beam is made extremely short and multiphoton absorption is caused to occur inside the workpiece, the energy of the multiphoton absorption is not converted into thermal energy, and the ionic valence. Permanent structural changes such as change, crystallization or polarization orientation are induced to form a refractive index change region. In the present embodiment, this refractive index change region is called a modified region.

  A mother substrate W2, which is a processing target of the present embodiment, has a plurality of microlenses 3 formed over almost the entire surface. When the laser beam 113 is scanned along the planned cutting lines Dx and Dy (see FIG. 4) with the condensing point positioned inside the mother substrate W2, the laser beam 113 incident on the hemispherical surface of the microlens 3 becomes the incident position. Therefore, the focal point is not necessarily located on the optical axis 101a. Therefore, it is difficult to form the modified region at a fixed position inside the microlens 3. Therefore, the substrate dividing method of this embodiment is used.

  FIG. 7 is a flowchart showing a substrate dividing method. As shown in FIG. 7, the method for dividing the mother substrate W2 according to the present embodiment includes a measurement process (step S1) for measuring the position of the microlens 3 positioned on the planned cutting lines Dx and Dy of the mother substrate W2. A calculation step (step S2) for obtaining an irradiation interval of the laser beam 113 on the microlens 3 based on the result, an irradiation step (step S3) for irradiating the mother substrate W2 with the laser beam 113 based on the calculation result, and the laser beam 113. And a dividing step (step S4) for dividing the mother substrate W2 irradiated with. Hereinafter, each step will be described with reference to FIGS. 8A to 8D are schematic cross-sectional views showing a method for dividing a substrate, FIGS. 9A to 9C are schematic views showing a method for irradiating a microlens as an optical element with a laser beam, and FIG. FIG. 11A and FIG. 11B are schematic cross-sectional views showing a dividing step, showing an example of the formation state of the modified region.

  Step S1 in FIG. 7 is a measurement process. In step S1, as shown in FIG. 8A, the mother substrate W2 is placed on the stage 105 with the glass substrate 2 side facing down. The stage control unit 123 moves the stage 105 by driving the servo motor so that the optical axis 101a and the planned cutting line Dx of the mother substrate W2 coincide. The lens control unit 122 positions the condenser lens 103 by driving the Z-axis slide mechanism 104 so that the focal point of the visible light 110 a emitted from the imaging mechanism 110 is located on the surface of the light shielding film 13. Then, scanning is performed to move the stage 105 in the direction of the arrow along the planned cutting line Dx. The main computer 120 obtains image information from the imaging mechanism 110 via the image processing unit 124. The formation position information of the light shielding film 13 along the planned cutting line Dx can be obtained from this image information, and the positional information (specifically, dimension m) of the microlens 3 along the planned cutting line Dx can be obtained. Can do. In this case, the dimension m is approximately 120 μm.

  In the above scanning, the position information of the microlens 3 may be obtained from the imaging mechanism 110 by moving the position of the condenser lens 103 so that the focal point of the visible light 110 a is focused on the hemispherical surface of the microlens 3. In this way, position information of the microlens 3 in the Z-axis direction can also be obtained.

  Such acquisition of the position information of the microlens 3 is naturally performed also in the direction along the planned cutting line Dy. In the present embodiment, since the plurality of counter substrates 1 are formed in a matrix on the mother substrate W2, all the cutting is performed by scanning the visible light 110a once along each of the planned cutting lines Dx and Dy. Position information of the microlenses 3 located on the planned lines Dx and Dy can be obtained. Then, the process proceeds to step S2.

  Step S2 in FIG. 7 is a calculation process. In step S2, an irradiation interval for irradiating the microlens 3 with the laser beam 113 is calculated based on the position information of the microlens 3 obtained in the measurement process. More specifically, in this case, as shown in FIG. 9A, the scheduled cutting lines Dx and Dy are set to be orthogonal to the optical axis 3 a of the microlens 3. Therefore, the distance Lm between the optical axes 3a is obtained. Since the microlenses 3 are periodically arranged, the interval Lm is approximately 120 μm.

  FIG. 9B is a schematic plan view of the micro lens viewed from the Z-axis direction, and FIG. 9C is a schematic cross-sectional view of the micro lens viewed from the direction along the planned cutting line. As shown in FIG. 9B, the liquid crystal display device 20 may not be able to set the planned cutting lines Dx and Dy so as to be orthogonal to the optical axis 3a. In other words, it is a case where the center lines of the plurality of microlenses 3 and the scheduled cutting lines Dx and Dy do not match in the X-axis direction or the Y-axis direction. In this case, as shown in FIG. 9C, since the laser beam 113 incident on the hemispherical surface of the microlens 3 is deviated from the optical axis 101a and condensed, the microlens 3 is considered in consideration of the deviation amount Δd. The irradiation position along the optical axis 3a, in other words, the position of the optical axis 101a of the laser beam 113 is obtained. In this way, the condensing point of the laser beam 113 can be positioned on the planned cutting lines Dx and Dy inside the microlens 3. Then, the process proceeds to step S3.

  Step S3 in FIG. 7 is an irradiation process of irradiating the laser beam 113. In step S3, first, as shown in FIG. 8B, the condensing lens 103 and the mother substrate W2 so that the condensing point of the laser beam 113 is located inside the microlens 3 located on the planned cutting line Dx. Are positioned in the X-axis direction, the Y-axis direction, and the Z-axis direction. Thereafter, the laser beam 113 is irradiated with an interval Lm while the mother substrate W2 is moved in the X-axis direction with respect to the condensing lens 103. As described above, the laser beam 113 is a femtosecond laser, that is, a pulse laser. Therefore, in order to irradiate the microlens 3 with the laser beam 113 at the interval Lm as the irradiation interval, the pulse interval of the laser beam 113, the relative movement speed of the stage 105 with respect to the condenser lens 103, and the opening / closing timing of the shutter 111 are taken into consideration. Must. If the relative movement speed is increased in order to ensure the productivity of laser processing, it is considered that the opening and closing of the shutter 111 that determines the irradiation interval cannot catch up. Therefore, in this embodiment, the pulse period is adjusted with the shutter 111 open. Specifically, the relative movement speed was a constant 120 mm / second, and the pulse interval was 1 kHz. Thereby, it becomes possible to irradiate the microlens 3 with the laser beam 113 at an interval Lm of 120 μm. If the interval Lm is 20 μm, the pulse period is obtained by dividing the relative movement speed by the interval Lm, and thus becomes 6 kHz. That is, even if the microlens 3 is finely formed, it is possible to irradiate the laser beam 113 with a desired irradiation interval by adjusting the pulse period with respect to the relative movement speed.

  Multiphoton absorption occurs in the condensing region of the laser light 113 inside the microlens 3. The size of the modified region formed by multiphoton absorption varies depending on conditions such as the material of the microlens 3, the refractive index, and axial chromatic aberration when the irradiation energy of the laser beam 113 is constant. In this case, the modified region becomes smaller than when the laser beam 113 is focused on the quartz glass. Therefore, the position of the condensing point is moved along the optical axis 3a inside the microlens 3, and scanning is performed in which the laser beam 113 is irradiated again at the irradiation interval along the scheduled cutting line Dx. As a result, as shown in FIG. 8C, the modified region 21 is formed inside the microlens 3 along the optical axis 3a.

  Next, the condensing lens 103 is positioned in the Z-axis direction so that the condensing point is located inside the transparent resin layer 4, and scanning is performed in which the laser beam 113 is continuously irradiated along the planned cutting line Dx. In this case, since the scanning of irradiating the laser beam 113 by shifting the position of the condensing point in the Z-axis direction was performed twice, the two modified regions 22 are formed in the transparent resin layer 4 as shown in FIG. , 23 are formed. Such scanning is performed not only on the other scheduled cutting lines Dx but also on the planned cutting lines Dy.

  Next, as shown in FIG. 8D, the mother substrate W <b> 2 is reversed and placed on the stage 105. Then, the laser beam 113 is made incident from the surface 2a of the glass substrate 2, the condensing point is positioned inside the glass substrate 2, and scanning is performed to continuously irradiate the laser beam 113 along the scheduled cutting lines Dx and Dy. . Also in this case, the scanning of irradiating the laser beam 113 with the position of the condensing point shifted in the Z-axis direction according to the thickness of the glass substrate 2 was repeated. Then, the process proceeds to step S4.

  Step S4 in FIG. 7 is a dividing step. As shown in FIG. 10, in the preceding irradiation process, inside the counter substrate 1 along the scheduled cutting lines Dx and Dy, a modified region 21 is formed in the Z-axis direction at each microlens 3 portion, and transparent resin In the layer 4 and the glass substrate 2, modified regions 22, 23, 24, and 25 that are continuous in the Z-axis direction and the direction of the cutting lines Dx and Dy are formed. As shown in FIG. 11A, when these modified regions 21 to 25 are viewed from the direction (X-axis or Y-axis direction) along the planned cutting lines Dx and Dy, the thickness direction (Z-axis) of the mother substrate W2 The modified layer Rc continuous in the direction) is formed. In step S4, a force in the direction of the arrow is applied to the mother substrate W2 so as to divide the modified layer Rc. Then, as shown in FIG. 11B, the mother substrate W2 can be easily divided starting from the modified layer Rc. In this way, the mother substrate W2 is divided along the scheduled cutting lines Dx and Dy, and the individual counter substrate 1 is taken out.

  According to such a dividing method of the mother substrate W2, even if the microlenses 3 are formed periodically, the laser light 113 is irradiated to the microlenses 3 at the above-described irradiation interval, and therefore the laser light 113 is collected inside. The position of the light spot is stable, and the modified layer Rc is formed along the predetermined cutting scheduled lines Dx and Dy, and can be divided with high accuracy.

  The direction in which the laser beam 113 is incident on the microlens 3 may be from the surface 4a of the transparent resin layer 4 (see FIG. 8C) or from the surface 2a of the glass substrate 2 (see FIG. 8D). . Preferably, the light is incident from the surface having a lower refractive index than that of the microlens 3. In this case, the laser beam 113 is easily collected inside the microlens 3.

  Further, in the present embodiment, as shown in FIGS. 8A to 8D, the mother substrate is provided in a necessary region so that the counter electrode 5 and the alignment film 6 do not cover the cutting lines Dx and Dy. W2 is formed. Compared with the case where the counter electrode 5 and the alignment film 6 are formed over the entire surface of the mother substrate W2, this can reduce the loss of energy by the laser light 113 being absorbed by the counter electrode 5 and the alignment film 6. .

The effects of this embodiment are as follows.
(1) According to the method for dividing the mother substrate W2 of the above embodiment, the microlenses 3 are periodically formed on the quartz glass substrate, and the irradiation interval (interval Lm) according to the formation cycle (dimension m). Then, the laser beam 113 is irradiated. Further, since the optical axis 3 a of the microlens 3 and the optical axis 101 a of the laser beam 113 are matched, the laser beam 113 is incident on the microlens 3 at a constant incident angle. Therefore, the modified region 21 can be formed at a stable position inside the microlens 3 along the planned cutting lines Dx and Dy. Therefore, the mother substrate W2 having the plurality of microlenses 3 can be accurately divided at a predetermined position.

  (2) In the method for dividing the mother substrate W2 of the above embodiment, in the measurement step (step S1), visible light having substantially the same wavelength as the wavelength of the laser beam 113 is irradiated to measure the formation position of the microlens 3. Actually, the measurement can be performed close to the conditions for irradiating the microlens 3 with the laser beam 113. Therefore, more appropriate position information of the microlens 3 can be obtained.

  (3) In the method for dividing the mother substrate W2 of the above embodiment, in the irradiation step (step S3), the laser beam 113 is condensed inside the mother substrate W2 and relatively moved along the scheduled cutting lines Dx and Dy. Scanning is performed a plurality of times while changing the position of the condensing point. Therefore, the modified layer Rc continuous in the thickness direction of the mother substrate W2 is formed. Therefore, the mother substrate W2 can be easily divided starting from the modified layer Rc.

  (4) Since the manufacturing method of the liquid crystal display device 20 as the electro-optical device according to the above embodiment uses the dividing method of the mother substrate W2, the occurrence of defective outer shape of the counter substrate 1 is reduced, and the liquid crystal display with high yield is achieved. The device 20 can be manufactured.

  As mentioned above, although embodiment of this invention was described, various deformation | transformation can be added with respect to the said embodiment in the range which does not deviate from the meaning of this invention. For example, modifications other than the above embodiment are as follows.

  (Modification 1) In the method for dividing the mother substrate W2 of the above embodiment, the measurement step (step S1) is not essential. In the calculation step (step S2), the irradiation interval may be calculated based on the design information of the microlens 3 on the mother substrate W2.

  (Modification 2) In the method for dividing the mother substrate W2 of the above embodiment, the irradiation method of the laser beam 113 in the irradiation step (step S3) is not limited to this. For example, the laser beam 113 is first irradiated from the surface 2a of the glass substrate 2, the microlens 3 and the glass substrate 2 are laser processed (formation of a modified region), and then the mother substrate W2 is turned upside down to be transparent. Laser processing of the resin layer 4 may be performed.

  (Modification 3) In the method for dividing the mother substrate W2 of the above embodiment, the irradiation interval for irradiating the microlens 3 with the laser beam 113 is not limited to the interval Lm. For example, one interval Lm may be skipped, or the irradiation of the laser beam 113 in the middle such as an integer multiple of the interval Lm may be thinned out. Since the modified region is continuously formed in the thickness direction on the glass substrate 2 and the transparent resin layer 4 with the microlens 3 interposed therebetween, the mother substrate W2 can be divided. Therefore, the irradiation time of the laser beam 113 can be shortened.

  (Modification 4) In the method of dividing the mother substrate W2 of the above embodiment, the arrangement of the microlenses 3 is not limited to this. For example, a plurality of microlenses 3 may be arranged in the pixel portion 10 facing the pixel electrode 11.

  (Modification 5) In the method for dividing the mother substrate W2 of the above embodiment, the microlenses 3 are not limited to being formed periodically. For example, it is conceivable to arrange the microlenses 3 at unequal intervals in order to make the in-plane brightness uniform according to the luminance distribution of incident light incident on the liquid crystal display device 20. Even in that case, since the irradiation interval is determined based on the position information of the microlens 3, the division can be performed with high positional accuracy.

  (Modification 6) In the method of dividing the mother substrate W2 of the above embodiment, the laser beam 113 is not limited to a pulse laser such as a femtosecond laser. For example, continuous light (CW light) such as a YAG laser or a gas laser can be used. In that case, the microlens 3 as an optical element may be irradiated with the laser beam 113 by controlling the opening and closing of the shutter 111 so as to synchronize with the formation cycle.

  (Modification 7) The method of manufacturing the liquid crystal display device 20 of the above embodiment is not limited to this. For example, like the mother substrate W1, the mother substrate W2 is formed into a wafer shape, and the two mother substrates W1 and W2 are joined, and then divided by irradiating the laser beam 113 using the above-described substrate dividing method. It is also possible to remove the device 20.

  (Modification 8) In the method of manufacturing the liquid crystal display device 20 of the above embodiment, the configuration of the liquid crystal display device 20 is not limited to this. FIG. 12 is a schematic cross-sectional view showing a liquid crystal display device according to a modification. For example, as shown in FIG. 12, the liquid crystal display device 300 includes a counter substrate 301 and an element substrate 309 as a pair of substrates, and a liquid crystal 312 sandwiched between the substrates 301 and 309 and sealed with a sealant 313. Yes. The element substrate 309 includes pixel electrodes 310 arranged in a matrix and thin film transistors 311 as switching elements connected to the pixel electrodes 310. The counter substrate 301 includes a glass substrate 302, a microlens 303 formed by filling a concave portion 306 of the glass substrate 302 with a resin containing a photopolymer, and a cover glass 304 covering the resin portion. On the surface of the cover glass 304 facing the liquid crystal 312, a light shielding film 307 that partitions the pixel portion 305 and a counter electrode 308 formed so as to cover each light shielding film 307 are provided. Thus, even if the microlens 303 is provided in a concave shape, the substrate dividing method of the above embodiment can be applied.

  (Modification 9) In the above-described embodiment, the forms of the electro-optical device and the optical element are not limited thereto. FIG. 13 is a schematic cross-sectional view showing an organic EL device including an organic EL light emitting element. As shown in FIG. 13, the organic EL device 400 includes at least a functional layer 402 including an organic light emitting layer on a glass substrate 401 as one substrate, and a prism layer 403 formed so as to cover each functional layer 402. . In the prism layer 403, a plurality of prisms 404 having two inclined surfaces are formed. The width 404d of the prism 404 is narrower than the width d of the functional layer 402, and a plurality of prisms 404 are opposed to one functional layer 402. Therefore, light emitted by applying a current to the functional layer 402 is emitted through the prism 404 in a predetermined direction. That is, very bright emission light can be obtained when viewed from a certain direction. Even for a glass substrate 401 having such a prism 404 as an optical element, the above substrate dividing method can be applied. That is, it can be applied to a method for manufacturing an organic EL device having the glass substrate 401. As an optical element, in addition to a microlens and a prism, a Fresnel lens, a diffraction grating, a polarizing element, and the like can be considered.

Schematic which shows the structure of a projection type display apparatus. FIG. 2 is a schematic cross-sectional view illustrating a structure of a liquid crystal display device. (A) is a schematic plan view which shows a mother board | substrate, (b) is a schematic sectional drawing cut | disconnected by the AA line of (a). The schematic plan view which shows the mother substrate by the side of a counter substrate. Schematic which shows the structure of a laser irradiation apparatus. (A) And (b) is a schematic sectional drawing which shows the state which varied the position of the condensing area | region of the laser beam in the thickness direction of the workpiece. The flowchart which shows the division | segmentation method of a board | substrate. (A)-(d) is a schematic sectional drawing which shows the division | segmentation method of a board | substrate. (A)-(c) is schematic which shows the irradiation method of the laser beam with respect to the micro lens as an optical element. The schematic sectional drawing which shows an example of the formation state of a modification area | region. (A) And (b) is a schematic sectional drawing which shows a division | segmentation process. The schematic sectional drawing which shows the liquid crystal display device of a modification. The schematic sectional drawing which shows the organic EL apparatus provided with the organic EL light emitting element.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Counter substrate as a board | substrate, 3 ... Micro lens as an optical element, 3a ... Optical axis, 20 ... Liquid crystal display device as an electro-optical device, 110a ... Visible light as reference light, 111 ... Shutter, 113 ... Laser light And 300: a liquid crystal display device as a modified example as an electro-optical device, 301: a counter substrate as a substrate, 400: an organic EL device as an electro-optical device, 401: a glass substrate as a substrate, 404: an optical element Dx, Dy ... planned cutting line, Lm ... interval as irradiation interval, m ... dimension as period of optical element, W2 ... mother substrate.

Claims (8)

A method for dividing a substrate, which is capable of transmitting laser light and has at least one optical element at a position along a planned cutting line,
A calculation step for obtaining an irradiation interval of the laser light in a direction along the planned cutting line based on position information of the optical element on the substrate;
Scanning that relatively moves the laser light along the planned cutting line is performed a plurality of times within the substrate while changing the position of the condensing point of the laser light, and multiphoton absorption occurs at the condensing point. An irradiation step of irradiating to
A division step of dividing the substrate irradiated with the laser beam,
In the irradiation step, the substrate is divided at least once by performing the scanning at least once by irradiating the laser beam at the irradiation interval with the condensing point positioned inside the optical element. Further comprising a measuring step of irradiating the substrate with reference light and measuring the position of the optical element;
The substrate dividing method according to claim 1, wherein in the calculation step, the irradiation interval is obtained based on position information of the optical element obtained in the measurement step. In the calculation step, the position of the optical axis of the optical element in the direction along the planned cutting line is determined based on the position information of the optical element,
3. The substrate division according to claim 1, wherein in the irradiating step, the scanning is performed by irradiating the laser beam with the condensing point positioned on the optical axis inside the optical element. 4. Method. The optical element is periodically provided along the planned cutting line,
4. The method according to claim 1, wherein, in the irradiation step, the irradiation interval for irradiating the optical element with the laser light is the same as the period of the optical element or an integral multiple of the period. The method for dividing a substrate according to claim 1.   5. The irradiation interval is set in the irradiation step by setting a relative movement speed between the laser beam and the substrate to be constant, and controlling opening / closing of a shutter that blocks the laser beam. Substrate dividing method. Using pulsed laser light as the laser light,
In the irradiation step, the repetition rate of the pulse laser beam is set so that the relative movement speed between the pulse laser beam and the substrate is constant, and the irradiation interval is the same as the period of the optical element. The substrate dividing method according to claim 4.   The substrate dividing method according to claim 1, wherein the optical element is a microlens or a prism. A method of manufacturing an electro-optical device including a substrate capable of transmitting laser light and having at least one optical element at an outer position,
A substrate dividing method according to any one of claims 1 to 7, wherein the substrate is divided from the mother substrate by irradiating the laser light along a planned cutting line of the mother substrate. A method for manufacturing an electro-optical device.

Images