JP2005212364A - Fracturing system of brittle material and method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fracturing system of a brittle material and a method thereof which realize high-grade and high-speed fracturing of the brittle material. <P>SOLUTION: A board 60 to be worked is moved relatively in relation to a working part unit 5, and a fracturing line lead unit 10, a preheating unit 20, a fracturing unit 30 and a cooling unit 40 are moved relatively in this sequence along a predetermined fracturing line 71 on the board 60 to be worked. On the occasion, the board 60 is heated locally with a prescribed temperature by irradiating a linear laser beam LB2 by the fracturing unit 30, and then the board 60 is cooled locally by blowing a coolant C against the board 60 by the cooling unit 40. An irradiation pattern 66 of the linear laser beam LB2 irradiating the board 60 has a uniform intensity distribution with respect to the direction along the predetermined fracturing line 71. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cleaving system in which a substrate to be processed made of a brittle material (hard and brittle material) is locally heated, and the substrate to be processed is cracked by the thermal stress, and is particularly brittle. The present invention relates to a brittle material cleaving system and method capable of realizing high-quality and high-speed cleaving of a material.

  Conventionally, as a method of cleaving a work substrate made of a brittle material, (a) a surface of the work substrate is obtained by scratching the surface of the work substrate using a hard material such as diamond. A method of cleaving a substrate to be processed by forming a continuous and fine linear crack or processed groove on the substrate and then applying a pressure or impact load so as to expand the crack or processed groove; (b) Diamond A method is known in which a surface of a substrate to be processed is scribed using a grinding wheel such as a grindstone, and the substrate to be processed is cut along the processing line. Among these, the latter method (b) is generally used for cleaving glass substrates and the like in a manufacturing process for manufacturing a liquid crystal display, a plasma display panel (PDP), a field emission display (FED) and the like. ing.

  However, in the above method (a), irregular fine cracks that cause stress concentration are likely to remain on the cut surface of the substrate to be processed, and finishing processing such as polishing of the end face is necessary after cleaving. There are problems such as becoming.

  Further, the method (b) has a problem in that a machining margin is required to perform the scribing process. In addition, there is a problem that it is difficult to perform a scribing process on a workpiece substrate made of a hard brittle material. Furthermore, there is a problem that irregular surfaces such as burrs are easily generated on the surface of the cut surface of the substrate to be processed, and it is difficult to form a high-quality processed surface.

  In particular, when cleaving a glass substrate used for a liquid crystal display, a plasma display panel, a field emission display, etc. by using the method (b), (1) a blade for scribing with a grinding wheel (2) It takes time to readjust when replacing the blade, and wasteful time is required to stop the manufacturing process. (3) Burrs generated on the surface of the cut surface of the substrate to be processed (4) A thin glass substrate (for example, about 0.1 mm to about several millimeters) that is becoming common in recent years. (Thickness substrate) is difficult to cut, and there is a possibility that breakage or chipping may occur during scribing.

Under such circumstances, as a method of cleaving a glass substrate used for a liquid crystal display, a plasma display panel, a field emission display, etc., (c) a brittle material using a laser beam such as a CO ₂ laser (carbon dioxide laser) A method has been proposed in which a substrate to be processed is heated locally, and the substrate to be processed is cracked by the thermal stress (see Patent Documents 1 to 5).

In the method (c), even when the glass substrate is cleaved, (1) there is no problem associated with blade replacement because no grinding wheel is used, and (2) there is no burrs on the surface of the cut surface of the substrate to be processed. Further, there is an advantage that a cleaning process and a polishing process can be omitted because no dust or dust is generated, and (3) there is no possibility of breakage or chipping even when a thin glass substrate is cleaved.
Japanese National Patent Publication No. 8-509947 JP 10-34364 A JP 10-34363 A JP-A-7-323385 JP 2002-178179 A

  However, in the method (c) (a method of cleaving the substrate to be processed using a laser beam), the laser beam can be injected under the condition that the substrate to be processed is not damaged (melted, deformed, altered, etc.). Due to energy limitations, it was difficult to achieve high-quality cleaving of brittle materials at high speed. Specifically, for example, in the case of a glass substrate having a thickness on the order of 1 mm, in the case of surface cracking (micro crack method) (a method of cleaving only the surface of the glass substrate), the speed is suppressed to about several hundred mm / second or less. In the case of the Full Body Crack Method (a method of cleaving with the glass substrate penetrating from the front surface to the back surface), the speed has to be suppressed to about several tens of mm / second or less.

  The present invention has been made in consideration of such points, and an object of the present invention is to provide a brittle material cleaving system and method capable of realizing high-quality and high-speed cleaving of a brittle material. And

  As a first solution, the present invention provides a cleaving schedule in a cleaving system in which a substrate to be processed made of a brittle material is locally heated, and the substrate to be processed is cracked by the thermal stress. A cleaving unit that irradiates the substrate to be processed with a laser beam having a linear irradiation pattern extending in a direction along the line to locally heat the substrate to be processed, and the substrate to be processed with respect to the cleaving unit. A moving unit that moves the region that is heated locally on the substrate to be processed by the cleaving unit along the planned cutting line, and is arranged on the substrate to be processed by the cleaving unit. The irradiation pattern of the laser beam to be irradiated has a uniform intensity distribution in a direction along the planned cutting line, and the cutting processing system of the brittle material is characterized in that To provide a beam.

  In the first solving means described above, the irradiation pattern of the laser beam irradiated onto the substrate to be processed by the cleaving unit is such that the reference beam is repeated over a predetermined length along the planned cutting line. It is preferably generated by scanning. Moreover, it is preferable that the length of the irradiation pattern of the laser beam irradiated on the substrate to be processed by the cleaving unit in the direction along the planned cutting line exceeds 10 times the thickness of the substrate to be processed.

  Moreover, in the 1st solution means mentioned above, it is preferable to further provide the preheating unit which preheats the area | region where heating is locally performed on the said to-be-processed substrate by the said cleaving unit, and raises the temperature of the said area | region. Here, the preheating unit has a linear irradiation pattern extending in a direction along the planned cutting line, and a laser beam having an irradiation pattern whose intensity distribution is uniform with respect to the direction along the planned cutting line. It is preferable to preheat the substrate to be processed by irradiating the substrate. The laser beam irradiated onto the substrate to be processed by the preheating unit is preferably generated by repeatedly scanning a reference beam over a predetermined length along the planned cutting line.

  Furthermore, in the first solving means described above, it is preferable to further include a cooling unit that sprays a coolant onto a region heated locally on the substrate to be processed by the cleaving unit to cool the region. .

  As a second solution, the present invention provides a cleaving method in which a substrate to be processed made of a brittle material is locally heated and a crack is generated in the substrate to be processed by the thermal stress. A preparatory step for preparing a substrate to be processed, and a laser beam having a linear irradiation pattern extending in a direction along the planned cutting line is irradiated on the substrate to be heated while locally heating the substrate to be processed An irradiation pattern of the laser beam irradiated onto the substrate to be processed in the cleaving step, and a cleaving step of moving a region where heating is locally performed on the substrate to be processed along the planned cutting line Provides a method for cleaving a brittle material, characterized by having a uniform strength distribution in a direction along the planned cutting line.

  In the second solving means described above, the laser beam irradiated onto the substrate to be processed in the cleaving step repeatedly scans a reference beam over a predetermined length along the planned cutting line. It is preferable that it is produced | generated by. Moreover, it is preferable that the length of the irradiation pattern of the laser beam irradiated on the substrate to be processed in the cleaving step in the direction along the planned cutting line exceeds 10 times the thickness of the substrate to be processed.

  Further, the second solving means described above preferably further includes a preheating step of preheating a region where heating is locally performed on the substrate to be processed in the cleaving step to increase the temperature of the region. Here, in the preheating step, a laser beam having an irradiation pattern which is a linear irradiation pattern extending in a direction along the planned cutting line and whose intensity distribution is uniform in the direction along the predetermined cutting line is processed. It is preferable to preheat the substrate to be processed by irradiating the substrate. Further, it is preferable that the laser beam irradiated on the substrate to be processed in the preheating step is generated by repeatedly scanning a reference beam over a predetermined length along the planned cutting line.

  Furthermore, the second solving means described above preferably further includes a cooling step of cooling the region by spraying a coolant on the region heated locally on the workpiece substrate in the cleaving step. .

  According to the present invention, a processing target substrate is irradiated with a laser beam having a linear irradiation pattern extending in a direction along the planned cutting line, the intensity distribution of which is uniform in the direction along the planned cutting line. Since the region to be locally heated on the substrate to be processed is moved along the planned cutting line while locally heating the substrate to be processed, the substrate to be processed is not damaged. The beam intensity of the laser beam irradiated onto the substrate to be processed can be increased to the limit. For this reason, it is possible to apply a larger thermal stress (tensile stress) to the cracked portion of the substrate to be processed than in the case of a conventional laser beam having a Gaussian beam intensity. Moreover, high-speed cleaving can be realized.

  In addition, according to the present invention, a larger thermal stress (tensile stress) can be applied to the cracked portion of the substrate to be processed than in the case of a conventional laser beam having a Gaussian beam intensity. Even when a liquid crystal substrate in which two glass substrates are bonded together with a sealing material is used as a processed substrate, high-quality and high-speed cleaving can be realized.

  Furthermore, according to the present invention, since the cleaving process is performed by irradiating the substrate to be processed with a laser beam, the surface of the cut section of the substrate to be processed does not generate burrs or dust, and the cleaning process or finish The polishing process for the purpose can be omitted. Further, even when the thin substrate is cleaved, there is no risk of damage or chipping.

BEST MODE FOR CARRYING OUT THE INVENTION

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

  First, the overall configuration of the cleaving system according to one embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the cleaving system 1 performs heating by locally heating a workpiece substrate 60 made of a brittle material and causing a crack in the workpiece substrate 60 by the thermal stress. A processing unit 5 for cleaving the substrate 60 to be processed, and a moving unit 50 for supporting the substrate 60 and moving the substrate 60 relative to the processing unit 5 are provided. ing. Here, a liquid crystal substrate in which two glass substrates (an upper substrate 61 and a lower substrate 62) are bonded together with a sealant (not shown) is used as the substrate 60 to be cut.

  Among these, the processing unit 5 includes a cutting wire lead unit 10, a preheating unit 20, a cutting unit 30, and a cooling unit 40. These units are relatively arranged along a cutting line 71 on the substrate 60 to be processed. Is configured to move. The cutting wire lead unit 10, the preheating unit 20, the cutting unit 30, and the cooling unit 40 are arranged in a straight line in this order from the head side to the tail side in the moving direction on the substrate 60 to be processed.

  The details of the cutting wire lead unit 10, the preheating unit 20, the cutting unit 30, and the cooling unit 40 will be described below.

  The cutting wire lead unit 10 is for forming indentations (fine cracks) on the surface of the substrate 60 to be processed. The fixing unit 11 is fixed to a support member (not shown), and the fixing unit 11 The movable portion 12 is relatively moved in the vertical direction (Z direction), and the disk 13 is attached to the front end portion of the movable portion 12 and contacts the surface of the substrate 60 to be processed. Here, the disk 13 is preferably made of a member made of a hard material such as tungsten carbide, titanium carbide, cemented carbide, or tiremond. Moreover, it is preferable that the contact surface of the disk 13 has a mountain shape of about 30 ° to 150 °. Here, as the contact condition of the disk 13 to the workpiece substrate 60, various conditions (pressing force, displacement amount, etc.) can be selected according to the downward pressing manner by the movable portion 12.

The preheating unit 20 is for irradiating the laser beam LB1 on the substrate 60 on which the indentation is formed by the breaking wire lead unit 10 to locally preheat the substrate 60. The preheating unit 20 is about 200W to 300W. A laser oscillator 21 that emits a CO ₂ laser (a reference beam having a circular irradiation pattern), a reflection mirror 22 that reflects the reference beam emitted by the laser oscillator 21, and a reference beam that is reflected by the reflection mirror 22 And a polygon mirror 23 that scans on the processed substrate 60. As a result, the reference beam emitted from the laser oscillator 21 is reflected by the polygon mirror 23 via the reflection mirror 22 and repeatedly scanned over the predetermined length L1 along the planned cutting line 71 on the substrate 60 to be processed. As a result, a linear laser beam LB1 is generated. As shown in FIG. 2, the linear laser beam LB1 has a linear irradiation pattern 65 extending in a direction along the planned cutting line 71, and the intensity distribution thereof will be described later. It is uniform in the direction along.

The cleaving unit 30 is for irradiating the laser beam LB2 on the workpiece substrate 60 preheated locally by the preheating unit 20 to locally heat the workpiece substrate 60. A laser oscillator 31 that emits a CO ₂ laser of about 10 W (a reference beam having a circular irradiation pattern), a reflection mirror 32 that reflects the reference beam emitted by the laser oscillator 31, and a reflection mirror 32 that reflects the reference beam. And a polygon mirror 33 that scans the reference beam on the substrate 60 to be processed. As a result, the reference beam emitted from the laser oscillator 31 is reflected by the polygon mirror 33 through the reflecting mirror 32, and repeatedly scanned over the predetermined length L2 along the planned cutting line 71 on the substrate 60 to be processed. As a result, a linear laser beam LB2 is generated. As shown in FIG. 2, the linear laser beam LB2 has a linear irradiation pattern 66 extending in a direction along the planned cutting line 71, and the intensity distribution thereof will be described later. It is uniform in the direction along.

  The cooling unit 40 is for locally cooling the workpiece substrate 60 by spraying the coolant C onto the workpiece substrate 60 heated locally by the cleaving unit 30, and water or mist (water and gas and A cooling nozzle 41 for injecting a coolant C such as a gas such as nitrogen, a particulate solid such as carbon dioxide particles, a liquid such as alcohol, or a mist-like alcohol onto the surface of the substrate 60 to be processed. The cooling nozzle 41 preferably has a diameter (inner diameter) of several mm or less.

  In the above, the cutting wire lead unit 10, the preheating unit 20, the cutting unit 30, and the cooling unit 40 included in the processing unit 5 are all in the direction along the substrate 60 (X direction and Y direction) by the moving stage (not shown). The cutting wire lead unit 10, the preheating unit 20, the cutting unit 30, and the cooling unit 40 are all appropriately spaced along the cutting line 71 on the substrate 60. Thus, the alignment can be adjusted so as to be arranged in a straight line.

  On the other hand, the moving unit 50 is for moving the substrate 60 to be processed relative to the processing unit 5 including the cutting wire lead unit 10, the preheating unit 20, the cutting unit 30, and the cooling unit 40. A holder 51 for supporting the processing substrate 60, a positioning pin 52 for positioning the processing substrate 60 supported by the holder 51, and a movement for moving the holder 51 relative to the processing unit 5 in the XY plane. And a stage 53. Note that a linear support 54 is provided on the holder 51 to support a portion of the back surface of the substrate 60 to be processed corresponding to the planned cutting line 71. Here, the cross section of the support 54 has a triangular mountain shape, a hemispherical mountain shape, an elliptical mountain shape, a square mountain shape, and a polygonal mountain shape, and a fluororesin such as Teflon (registered trademark) or PEEK (registered trademark). It is preferably made of a member made of a material having such a hardness as not to damage the substrate to be processed 60, such as polyallyl ether ether ketone resin, acrylic, soft glass or the like.

  Next, the operation of the present embodiment having such a configuration will be described.

  In the cleaving system 1 shown in FIG. 1, a substrate 60 to be cleaved is positioned on a holder 51 mounted on a moving stage 53 of a moving unit 50. Specifically, an alignment mark (not shown) attached to the substrate 60 to be processed is imaged by a CCD force mela (not shown), and the substrate to be processed is based on an imaging result by an image processing device (not shown). The relative positional relationship between the two alignment marks is changed so that the 60 alignment marks are located at predetermined positions on the holder 51. As a result, the substrate to be processed 60 is positioned at a predetermined location on the holder 51. The workpiece substrate 60 positioned on the holder 51 in this way is fixed by positioning pins 52.

  Then, the holder 51 is moved by the moving stage 53 of the moving unit 50, and the processing unit 5 is positioned on the planned cutting line 71 of the substrate 60 to be processed positioned on the holder 51. It should be noted that the cutting wire lead unit 10, the preheating unit 20, the cutting unit 30, and the cooling unit 40 included in the processing unit 5 are placed on the cutting planned line 71 when positioned on the cutting planned line 71 of the substrate 60 to be processed. The alignment is adjusted in advance so as to be arranged in a straight line at appropriate intervals along the line.

  In this state, the substrate 60 positioned on the holder 51 is moved relative to the processing unit 5 by the moving stage 53 of the moving unit 50, and the breaking wire lead unit 10 included in the processing unit 5 is included. The preheating unit 20, the cleaving unit 30, and the cooling unit 40 are relatively moved in this order along the planned cutting line 71 on the substrate 60 to be processed.

  Thereby, as shown in FIGS. 1 and 2, first, the cutting wire lead unit 10 is relatively moved along the cutting planned line 71 in a state where the disk 13 is in contact with the surface of the substrate 60 to be processed. Indentations (fine cracks) having a depth of several hundred to several tens of μm are formed on the surface of the processed substrate 60. The depth D of the indentation is related to the thickness H of the substrate 60 to be processed. D = 35 μm (H = 0.2 mm), D = 45 μm (H = 0.4 mm), D = 65 μm (H = 0.7 mm) and D = 90 μm (H = 1 mm). This is because the substrate to be processed 60 is cleaved by the thermal stress generated by the laser beam LB2 irradiated by the cleaving unit 30, and the role of the impression formed by the cleaving wire lead unit 10 is mainly the actual cleaving line. This is because the crack 68 is merely for bringing the crack 68 closer to the planned cutting line 71. In addition, since the to-be-processed substrate 60 consists of brittle materials, such as glass, the deformation amount of the to-be-processed substrate 60 accompanying the indentation formed in this way is very slight, and such deformation is plastic flow (plasticity). Deformation). For this reason, almost no burrs, dust, chipping, or the like is generated on the surface of the fractured surface of the substrate 60 to be processed, and even if it occurs, the size is not large enough to affect the manufacturing process.

  Next, the preheating unit 20 relatively moves along the planned cutting line 71 on the substrate to be processed 60 in which the indentation is formed by the cutting line lead unit 10 in this way, and the indentation line on the processing substrate 60 is changed. By irradiating the linear region including the linear laser beam LB1, the substrate to be processed 60 is locally preheated at a predetermined temperature (about 30 ° C. to 200 ° C.). At this time, in the preheating unit 20, the reference beam emitted from the laser oscillator 21 is reflected by the polygon mirror 23 through the reflecting mirror 22, and has a predetermined length L1 along the planned cutting line 71 on the substrate 60 to be processed. By scanning repeatedly over a period of time, a linear laser beam LB1 having an irradiation pattern 65 is generated.

  Then, the cleaving unit 30 relatively moves along the planned cutting line 71 on the substrate 60 to be locally preheated by the preheating unit 20 in this way, and locally on the substrate 60 to be processed by the preheating unit 20. By irradiating a linear laser beam LB2 to a linear region that is narrower than the region that has been preheated locally, the substrate 60 to be processed is locally at a predetermined temperature (about 100 ° C. to 400 ° C.). Heat. At this time, in the cleaving unit 30, the reference beam emitted from the laser oscillator 31 is reflected by the polygon mirror 33 via the reflecting mirror 32, and has a predetermined length L2 along the planned cutting line 71 on the substrate 60 to be processed. By scanning repeatedly over a period of time, a linear laser beam LB2 having an irradiation pattern 66 is generated.

  Thereafter, the cooling unit 40 moves relatively along the planned cutting line 71 on the substrate 60 to be heated locally by the cleaving unit 30 in this manner, and the crushing unit 30 locally moves on the substrate 60 to be processed. The substrate 60 to be processed is locally cooled by spraying the coolant C onto a circular area that is wider than the area that has been heated. At this time, in the cooling unit 40, the coolant C sprayed from the cooling nozzle 41 is sprayed on the surface of the substrate 60 to be processed with a predetermined spray pattern 67.

  As described above, formation of an indentation by the breaking wire lead unit 10, preheating by the preheating unit 20, heating by the cutting unit 30, and cooling by the cooling unit 40 are sequentially performed along the planned cutting line 71 on the substrate 60 to be processed. A crack 68 is formed mainly by the thermal stress (tensile stress) generated by heating the workpiece substrate 60 and the tensile stress generated by cooling the workpiece substrate 60, and the break wire lead unit 10, the preheating unit 20, As the cleaving unit 30 and the cooling unit 40 relatively move along the planned cutting line 71 on the substrate 70, the crack 68 develops along the planned cutting line 71.

  Specifically, when the workpiece substrate 60 is locally heated by the cleaving unit 30, a crack 68 is generated in the workpiece substrate 60 due to thermal stress (tensile stress) generated by heating the workpiece substrate 60. In this state, when the region 66 to be locally heated on the substrate 60 to be moved is moved along the planned cutting line 71, the thermal stress generated by the heating by the cleaving unit 30 causes cracks in the substrate 60 to be processed. The cracks 68 are sequentially applied to the tip portions of the cracks 68 and follow the movement of the region 66 by an effect of stress expansion at the tip portions of the cracks 68 (“specific effect around the crack tip” in fracture engineering). To do.

  At this time, after the substrate 60 is locally heated by the cleaving unit 30, the region (irradiation pattern 66) that is locally heated on the substrate 60 by the cleaving unit 30 by the cooling unit 40. When the coolant C is sprayed on a circular area (corresponding to the spray pattern 67) wider than the tensile stress generated by cooling the substrate 60, the tensile stress generated by heating by the cleaving unit 30 And superimposed. Thereby, the tensile stress generated only by heating by the cleaving unit 30 is further expanded, and the stress expansion effect generated at the tip of the crack 68 of the substrate to be processed 60 is further increased, so that the crack 68 can be advanced at a higher speed. . When the crack 68 is caused to propagate by the thermal stress (tensile stress) generated by heating the workpiece substrate 60 and the tensile stress generated by cooling the workpiece substrate 60 in this way, the tip of the crack 68 is Usually, it is positioned in the vicinity of the cooling unit 40.

  Furthermore, in this state, prior to locally heating the substrate 60 to be processed by the cleaving unit 30, a region in which heating is locally performed on the substrate 60 to be processed by the cleaving unit 30 (actually by the cleaving unit 30. Area where the heating is locally performed on the substrate 60 to be processed by the cleaving unit 30 when the area (corresponding to the irradiation pattern 65) (corresponding to the irradiation pattern 65) is locally preheated. Can be raised in advance, and heating for cleaving performed by the cleaving unit 30 can be effectively assisted.

  In the above, the linear laser beam LB1 irradiated on the substrate 60 by the preheating unit 20 has a linear irradiation pattern 65 extending in a direction along the planned cutting line 71 as shown in FIG. The width W1 (the length in the direction perpendicular to the planned cutting line 71) is about several millimeters to several tens of millimeters, and the length L1 (the length in the direction along the planned cutting line 71) is several. The length is preferably about 10 mm to reach the entire length of the substrate 60 to be processed.

  Further, the linear laser beam LB2 irradiated onto the workpiece substrate 60 by the cleaving unit 30 has a linear irradiation pattern 66 extending in a direction along the planned cutting line 71 as shown in FIG. The width W2 (the length in the direction orthogonal to the planned cutting line 71) is about several millimeters to several tens of mm, and the length L2 (the length in the direction along the planned cutting line 71) is several mm to hundreds. It is preferable to be about mm.

  Note that the length L2 of the irradiation pattern 66 of such a linear laser beam LB2 is sufficiently longer than the thickness H of the substrate 60 to be processed, and specifically, it is preferable to exceed 10 times the thickness H. .

  This is because the length L2 of the irradiation pattern 66 of the linear laser beam LB2 is made sufficiently long with respect to the thickness H of the substrate 60 to be processed, so that the heat applied to the laser beam LB2 is processed. According to the present invention, it is possible to sufficiently transmit from the front surface of the substrate 60 to the back surface through the inside, and accordingly, thermal stress can be applied not only to the surface of the substrate 60 to be processed but also to the inside and back surface. According to the results found by various experiments by the authors.

In general, the CO ₂ laser emitted from the laser oscillator 31 of the cleaving unit 30 is very well absorbed by the glass that is the material of the substrate to be processed 60, so that the depth of the wavelength order (about approximately) from the surface irradiated with the CO ₂ laser. It is absorbed at about 10 μm). For this reason, the CO ₂ laser does not enter the substrate 60 to be processed, and in order to transfer heat to the back surface of the substrate 60, the heat generated on the surface of the substrate 60 is conducted to the back surface. I have to wait. However, glass, which is the material of the substrate to be processed 60, has a low thermal conductivity, unlike metals, etc. Therefore, in order to transfer the heat generated on the surface of the glass to the back surface, a laser with a constant power is relatively used. It is necessary to irradiate over a long irradiation time. Here, even if the laser power is increased in order to obtain a large thermal stress, if the irradiation time is short, the thermal stress is not sufficiently transmitted to the inside of the glass, and only the surface thereof is cleaved. If the power of the laser is increased too much, the glass surface melts beyond the melting point due to heat, resulting in “melting” or “cutting” instead of “cutting”. In addition, “melting” or “cutting” is a phenomenon accompanied by disappearance of the substance. Compared with “cleaving” where no disappearance of the substance occurs, the processing surface is inferior in terms of surface roughness and surface properties. Later, a cleaning process for removing burrs and dust, a polishing process for finishing, and the like are required.

Here, it is preferable that the linear laser beams LB1 and LB2 irradiated onto the workpiece substrate 60 by the preheating unit 20 and the cleaving unit 30 do not overlap each other. This is because when the laser beams LB1 and LB2 overlap each other on the substrate to be processed 60, the energy density increases at the overlapped portion. That, _{P 1} the energy density of the laser beam LB1 is irradiated by preheating unit 20, when the energy density of the laser beam LB2 is irradiated by cleaving unit 30 and _{P 2,} the energy density at overlapped portions _P 1 + _{P 2} become. Here, if the energy density at which the surface of the substrate to be processed 60 reaches the melting point is W, W> P ₁ + P ₂ is necessary as a condition for causing the cleaving phenomenon, and if W <P ₁ + P ₂ It will be blown or cut. Therefore, in order to increase the speed of the fracture, it is preferable to increase the P ₂ as much as possible under the condition that W> P _2, is because it is advantageous to ensure that non-overlapping in order that .

  Further, the irradiation patterns 65 and 66 of the linear laser beams LB1 and LB2 irradiated onto the substrate 60 by the preheating unit 20 and the cleaving unit 30 have a uniform intensity distribution in the direction along the planned cutting line 71. ing. This is because, when the laser beam is spatially expanded, the intensity distribution is uneven depending on the expanded position, whereas the reference beam is split along the planned cutting line 71 on the substrate 60 to be processed by a predetermined length. This is because when the laser beam is generated by scanning over the lengths L1 and L2, there is little unevenness in intensity distribution depending on the location.

  In FIG. 3B, the irradiation pattern (beam spot) of the reference beam is represented by the symbol SP, and the linear laser beams LB1 and LB2 are obtained by repeatedly scanning the beam spot SP in the SU section. Generated.

  Hereinafter, a specific description will be given with reference to FIGS. It is assumed that the reference beam is scanned on the workpiece substrate 60 at the scanning speed Vb, and the workpiece substrate 60 is moving at the velocity Vs. Note that the scanning speed Vb of the reference beam is designed to be a sufficient speed and Vb = N · Vs (1) (where N is a constant of 100 to 1000 (design) Value)).

Next, assuming that the length of the SU section of the scanned reference beam is L, and the time during which the reference beam scans the section is δτ, δτ≈L / Vb (2). Furthermore, when the state of this repeated scanning every δτ time is expressed with reference to the substrate 60 to be processed, it becomes as shown in FIG. As shown in FIG. 8C, the substrate to be processed 60 moves by ε (the reference beam relatively moves by ε) in each scan of the reference beam, and the multiple times of irradiation (the reference beam repeats at a certain spot). The substrate to be processed 60 is irradiated with M). Here, since the reference beam is repeatedly scanned at time δτ, ε = Vs · δt (3). Here, when M is obtained, M = L / ε, and M = N if the above equations (1) to (3) are used. That is, the number M of times the reference beam is irradiated to an arbitrary region G as shown in FIG. 8C is equal to the magnification N of the reference beam scanning speed Vb with respect to the speed Vs of the substrate 60 to be processed. Here, since N is a sufficiently large constant, for example, 100 to 1000, the number M of irradiation of the reference beam is also sufficiently large. Suppose that energy given by a single reference beam irradiation for the region G is δE, δE has a statistical fluctuation, and has a Gaussian distribution with an average value of Eav and a standard deviation of δav. The total energy E given by N (= M) repetitive scans has a Gaussian distribution with an average value of N · Eav and a standard deviation of (N ^1/2 ) · δav.

As can be seen from this, as a result, the total energy E given by the linear laser beams LB1 and LB2 is N times, but the statistical fluctuation is only N1 ^{/ 2} . That is, the statistical fluctuation with respect to the average value of the total energy E can be reduced to ^{N1 / 2} . This is true not only for the region G shown in FIG. 8C, but also for all regions scanned with the reference beam.

Therefore, as described above, if the reference beam is repeatedly scanned with sufficiently large N, the statistical fluctuations of the beam intensities of the linear laser beams LB1 and LB2 can be reduced to ^{N1 / 2.} It is possible to irradiate a laser beam that is uniform and time-stable.

That is, (the profile of the beam intensity) intensity distribution of the A-A 'cross section of the radiation pattern of the linear laser beam LB1, LB2, as shown in FIG. 3 (a), rectangular profile A ₀ becomes, S- A substantially constant beam intensity is taken in the U section.

On the other hand, an elliptical beam (a laser beam having an elliptical irradiation pattern) that covers a predetermined length (SU section) along the planned cutting line 71 in the same manner as the linear laser beams LB1 and LB2. (See FIG. 3 (c)), and taking the intensity distribution (beam intensity profile) of the elliptical beam irradiation pattern (beam spot) on the BB 'cross section, as shown in FIG. 3 (a) , A Gaussian distribution profile B ₀ . This is because the laser beam emitted from the laser oscillator generally has a Gaussian distribution characteristic, and this characteristic is preserved even when the substrate 60 is irradiated.

Here, a point P in the beam spot of such an elliptical beam is considered. The beam energy E _p irradiated to this point P per unit time δτ is E _p = I ₀ · δτ, where I ₀ is the beam intensity. Here, when the energy input to the substrate to be processed 60 per unit area and unit time increases, the substrate to be processed 60 is melted and damaged, and even if it is not melted, it is damaged such as deformation and alteration. .

Now, let L ₀ be the critical beam intensity at which damage is caused to the substrate 60 to be processed.

In this case, in a laser beam having a Gaussian beam intensity, when the profile is B ₀ , I ₀ <L ₀ , so that there is still room for energy that can be input. Thus, if only think about the point P, it is possible to increase the beam intensity until the profile B ₁ strongly beam intensity overall. However, when the profile is actually B ₁ , the beam intensity is I ₀ > L _{0 in the} PQ section due to the characteristics of the Gaussian distribution, and the workpiece substrate 60 is damaged in this region. Become. Therefore, when irradiating a laser beam beam intensity takes a Gaussian distribution substrate to be processed 60, the beam intensity peak value of the Gaussian distribution is equal to L ₀ is the maximum of the beam intensity that can be turned on.

On the other hand, in the case of the profile A ₀ in which the beam intensity is constant in the SU section, the beam intensity is increased without damaging the substrate 60 until the constant portion matches the L _0. Therefore, a larger thermal stress (tensile stress) can be applied to the crack portion of the substrate 60 to be processed.

  The above points will be described in more detail with reference to FIGS. 4 (a) and 4 (b). 4A shows the temperature change (time change) at the point P when the laser beam passes through one point P on the substrate 60, and FIG. 4B shows the substrate to be processed. When the laser beam passes through one point P on 60, the change (time change) of the beam intensity at that point P is shown.

As shown in FIG. 4 (a), the substrate to be processed 60 on the laser beam is moved, when it is assumed to be irradiated to the point P at time T _1, the temperature at that time rises theta ₁ from theta _0.

Here, when the beam intensity of the laser beam has a Gaussian distribution and the profile is B ₀ (see FIG. 4B), the temperature of the substrate 60 to be processed changes as shown by the curve Θ _b , and the laser the beam intensity of the beam is constant, the profile is the case where a ₀ (see FIG. 4 (b)), the temperature of the substrate to be processed 60 changes as curve theta _a. In this case, the maximum temperature theta ₃ curves theta _{a maximum} temperature curve theta _b is theta _2, the melting point of the substrate to be processed 60 is assumed to be _{θ L, θ L> θ 3} > θ 2 relationship It has become. Therefore, when the curve of the temperature change is theta _a tensile obtained (profile of the beam intensity may be A ₀₎ stress, when the curve of the temperature change is theta _b (profile of the beam intensity B ₀ In this case, the cleaving speed and cleaving quality of the substrate to be processed 60 can be further improved.

  As described above, according to the present embodiment, the laser includes the irradiation pattern 66 that is a linear irradiation pattern 66 extending in the direction along the planned cutting line 71 and whose intensity distribution is uniform in the direction along the planned cutting line 71. The region to be locally heated on the substrate to be processed 60 is moved along the planned cutting line 71 while the substrate to be processed 60 is irradiated with the beam LB2 and locally heated. Therefore, the beam intensity of the laser beam LB2 irradiated to the substrate to be processed 60 can be increased to the limit as long as the substrate to be processed 60 is not damaged. For this reason, compared with the case of the conventional laser beam in which the beam intensity has a Gaussian distribution, a larger thermal stress (tensile stress) can be applied to the cracked portion of the substrate 60 to be processed. High quality and high speed cleaving can be realized. Specifically, for example, when a glass substrate having a thickness of the order of 1 mm is taken as an example, in the case of surface cleaving, a speed of about several hundred mm / second to 1000 mm / second is achieved, and in the case of all cleaving. Can achieve a speed of several hundred mm / second or more.

  Further, according to the present embodiment, it is possible to apply a larger thermal stress (tensile stress) to the cracked portion of the substrate 60 to be processed than in the case of a conventional laser beam having a Gaussian beam intensity. Therefore, even when a liquid crystal substrate in which two glass substrates (an upper substrate 61 and a lower substrate 62) are bonded together via a sealing material (not shown) is used as the substrate to be processed 60, it is of high quality. Moreover, high-speed cleaving can be realized. In general, in such a liquid crystal substrate, it is very difficult to perform cleaving due to the bonding between the sealing material and the substrate. However, in this embodiment, it is larger than the crack portion of the substrate 60 to be processed. Since thermal stress (tensile stress) can be applied, high-quality and high-speed cleaving can be easily realized as in the case of a substrate to be processed consisting of a single substrate.

  Furthermore, according to the present embodiment, since the cleaving process is performed by irradiating the workpiece substrate 60 with a laser beam, burrs and dust are not generated on the surface of the fractured surface, and the cleaning process and the finishing process are performed. Therefore, there is no possibility that damage or chipping occurs even for a thin substrate (for example, 0.4 mm or less). In particular, in the case of a thin substrate, since the time until the heat of the laser beam is transmitted to the back surface of the substrate is shortened, if the power of the laser beam is the same, the cleaving can be performed at a higher speed. If the beam moving speed (cleaving speed) is the same, the cleaving can be performed with a laser beam having a smaller power, and the system can be realized in a small size and at a low cost.

  In the above-described embodiment, the polygon mirrors 23 and 33 are used as optical components for scanning the reference beam on the substrate 60 to be processed in the preheating unit 20 and the cleaving unit 30. However, the present invention is not limited to this. For example, a galvanometer mirror 35 as shown in FIG. 5A or a cylindrical reflector 36 as shown in FIG. 5B may be used. In addition, as such an optical component, any of a transmission type and a non-transmission type (reflection type) can be used.

  In the above-described embodiment, the cooling unit 40 includes the Y stage 42 for moving the cooling nozzle 41 in the direction along the substrate 60 (for example, the Y direction), as shown in FIG. A Z stage 43 for moving the cooling nozzle 41 in a direction (Z direction) perpendicular to the substrate 60 to be processed may be provided. In this way, the distance (gap in the Z direction) between the tip of the cooling nozzle 41 and the substrate to be processed 60 can be adjusted as appropriate, and the spray pattern 67 of the coolant C sprayed on the substrate to be processed 60. (Cooling spot) can be changed. That is, when the distance between the tip of the cooling nozzle 41 and the substrate 60 to be processed becomes small, the spray pattern 67 ′ of the coolant C sprayed onto the substrate to be processed 60 becomes small as shown in FIG. . In contrast, when the distance between the tip of the cooling nozzle 41 and the substrate 60 to be processed becomes large, as shown in FIG. 6C, a spray pattern 67 ″ of the coolant C sprayed on the substrate 60 is formed. For this reason, by utilizing such a relationship, the gap between the tip of the cooling nozzle 41 and the substrate 60 to be processed is determined according to the power of the laser beam LB2 irradiated on the substrate 60 to be processed by the cleaving unit 30. By appropriately adjusting the distance, the cooling by the cooling unit 40 can be performed with an optimum degree and range corresponding to the degree and range of heating performed by the cleaving unit 30.

  Furthermore, in the above-described embodiment, the substrate to be processed 60 is supported by the support 54 provided on the holder 51. However, the present invention is not limited to this, and as shown in FIG. A pad 55 may be provided, and the workpiece substrate 60 may be lifted and supported by ejecting air or other gas (including nitrogen or oxygen) from the air pad 55. Further, a suction pad 56 for sucking and holding the back surface of the substrate 60 to be processed may be provided. Furthermore, by providing both the air pad 55 and the suction pad 56, the substrate 60 to be processed is effectively fixed by using the suction pad 56 because the substrate 60 is levitated so that the in-plane restraint force becomes extremely small. This makes it possible to effectively prevent the displacement of the substrate 60 to be processed due to vibrations associated with the operation of the cleaving system 1 or external vibrations. Note that the temperature of the gas ejected from the air pad 55 does not need to be the atmospheric temperature, and a gas having a high temperature (for example, about 70 ° C.) that does not damage the workpiece substrate 60 may be used. Thereby, it becomes possible to pre-heat the to-be-processed substrate 60 with the gas ejected from the air pad 55, and the cleaving speed and cleaving quality of the to-be-processed substrate 60 can be further improved.

  Further, in the above-described embodiment, an indentation is formed on the surface of the substrate 60 to be processed along the planned cutting line 71 by the cutting line lead unit 10, but the cause of the disturbance is small and the actual cutting line is used. When the error between a certain crack 68 and the planned cutting line 71 is within a desired accuracy, the cutting line lead unit 10 itself can be omitted.

  Furthermore, in the above-described embodiment, the workpiece unit 60 and the workpiece substrate 60 are moved by moving the workpiece substrate 60 side (holder 51 side) relative to the workpiece unit 5 by the moving stage 53 of the moving unit 50. Although the relative movement is realized, the present invention is not limited thereto, and the relative movement between the processing unit 5 and the substrate 60 to be processed can be realized by moving the processing unit 5 side. Good.

  Furthermore, in the above-described embodiment, a liquid crystal in which two glass substrates (an upper substrate 61 and a lower substrate 62) are bonded via a sealing material (not shown) as the substrate 60 to be cut. Although a substrate is used, a high-quality and high-speed cleaving process can be similarly performed on a liquid crystal substrate in a state where a liquid crystal material is injected between the upper substrate 61 and the lower substrate 62. Specifically, for example, a portion outside the sealing material for sealing the liquid crystal in such a liquid crystal substrate (about 1 mm from the liquid crystal edge in the in-plane direction of the substrate and the thickness of the substrate in the thickness direction of the substrate) (Sites separated by about 1 mm to 0.5 mm) are cleaved. However, in this case, the temperature at which the surface temperature of the glass substrate does not exceed the glass strain point, and the liquid crystal is damaged at the liquid crystal contact portion on the back surface of the glass substrate so that it does not operate normally (about 80 ° C. The parameters such as the power and irradiation time of the laser beams LB1 and LB2 irradiated by the preheating unit 20 and the cleaving unit 30 and the amount and temperature of the coolant C sprayed by the cooling unit 30 are set to prevent the preheating temperature. It is preferable to adjust the heating temperature and the cooling temperature.

The figure which shows the whole structure of the cleaving processing system which concerns on one embodiment of this invention. The figure for demonstrating the mode of the cleaving process of the to-be-processed substrate performed with the cleaving system shown in FIG. The figure for demonstrating intensity distribution of the laser beam irradiated by the preheating unit and cleaving unit of the cleaving processing system shown in FIG. The figure for demonstrating the temperature change (time change) and the intensity | strength change (time change) in a predetermined point by the laser beam irradiated by the preheating unit and cleaving unit of the cleaving processing system shown in FIG. . The figure which shows the modification of the preheating unit and cleaving unit of the cleaving processing system shown in FIG. The figure for demonstrating the detail of the cooling unit of the cleaving processing system shown in FIG. The figure which shows the modification of the holder for the to-be-processed substrates of the cleaving system shown in FIG. The figure for demonstrating the detail of the beam intensity of the laser beam shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cleaving processing system 5 Processing part unit 10 Cutting line lead unit 11 Fixed part 12 Movable part 13 Disk 20 Preheating unit 21 Laser oscillator 22 Reflecting mirror 23 Polygon mirror 30 Cleaving unit 31 Laser oscillator 32 Reflecting mirror 33 Polygon mirror 35 Galvano mirror 36 Cylinder Type reflection mirror 40 Cooling unit 41 Cooling nozzle 42 Y stage 43 Z stage 50 Moving unit 51 Holder 52 Positioning pin 53 Moving stage 54 Support 55 Air pad 56 Suction pad 60 Substrate 61 Upper substrate 62 Lower substrate 65, 66 Laser beam Irradiation pattern 67, 67 ', 67 "Coolant spray pattern 68 Crack (breaking line)
71 Scheduled cutting line LB1, LB2 Laser beam C Coolant

Claims (14)

In the cleaving processing system that heats the processing substrate made of a brittle material locally and cleaves the processing substrate by generating a crack in the processing substrate,
A cleaving unit that irradiates the substrate to be processed with a laser beam having a linear irradiation pattern extending in a direction along the planned cutting line, and locally heats the substrate to be processed;
A moving unit that moves the substrate to be processed relative to the cleaving unit, and moves a region that is locally heated on the substrate to be processed by the cleaving unit along the planned cutting line. ,
The cleaving processing system, wherein the irradiation pattern of the laser beam irradiated onto the substrate to be processed by the cleaving unit has a uniform intensity distribution in a direction along the planned cutting line.   An irradiation pattern of the laser beam irradiated onto the substrate to be processed by the cleaving unit is generated by repeatedly scanning a reference beam over a predetermined length along the planned cutting line. The cleaving system according to claim 1.   Of the irradiation pattern of the laser beam irradiated onto the substrate to be processed by the cleaving unit, the length in the direction along the planned cutting line exceeds 10 times the thickness of the substrate to be processed, The cleaving system according to claim 1 or 2.   4. The apparatus according to claim 1, further comprising a preheating unit that preheats a region where heating is locally performed on the substrate to be processed by the cleaving unit to raise a temperature of the region. 5. The cleaving system described in the item.   The preheating unit has a linear irradiation pattern extending in a direction along the planned cutting line, and a laser beam having an irradiation pattern whose intensity distribution is uniform in the direction along the planned cutting line on the substrate to be processed. The cleaving system according to claim 4, wherein the substrate to be processed is preheated by irradiation.   The laser beam irradiated onto the substrate to be processed by the preheating unit is generated by repeatedly scanning a reference beam over a predetermined length along the planned cutting line. Item 6. The cleaving system according to item 5.   The cooling unit for spraying a coolant on a region heated locally on the substrate to be processed by the cleaving unit to cool the region, further comprising a cooling unit. The cleaving system according to one item. In the cleaving method of locally heating a substrate to be processed made of a brittle material and performing cleaving by generating a crack in the substrate to be processed by the thermal stress,
A preparation step of preparing a substrate to be cut;
While the substrate to be processed is irradiated with a laser beam having a linear irradiation pattern extending in a direction along the planned cutting line, the substrate to be processed is locally heated, and the substrate is locally heated on the substrate to be processed. A cleaving step of moving the area to be performed along the planned cutting line,
The cleaving method, wherein an irradiation pattern of the laser beam irradiated on the substrate to be processed in the cleaving step has a uniform intensity distribution in a direction along the cleaving line.   The laser beam irradiated onto the substrate to be processed in the cleaving step is generated by repeatedly scanning a reference beam over a predetermined length along the planned cutting line. Item 9. The cleaving method according to Item 8.   Of the irradiation pattern of the laser beam irradiated onto the substrate to be processed in the cleaving step, the length in the direction along the planned cutting line exceeds 10 times the thickness of the substrate to be processed, The cleaving method according to claim 8 or 9.   11. The method according to claim 8, further comprising a preheating step of preheating a region where heating is locally performed on the substrate to be processed in the cleaving step to increase a temperature of the region. The cleaving method described in 1.   In the preheating step, a laser beam having an irradiation pattern that is a linear irradiation pattern extending in a direction along the planned cutting line and whose intensity distribution is uniform in a direction along the predetermined cutting line is formed on the substrate to be processed. The cleaving method according to claim 11, wherein the substrate to be processed is preheated by irradiation.   The laser beam irradiated onto the substrate to be processed in the preheating step is generated by repeatedly scanning a reference beam over a predetermined length along the planned cutting line. Item 15. The cleaving method according to Item 12.   14. The method according to claim 8, further comprising a cooling step of cooling the region by spraying a coolant to the region heated locally on the substrate to be processed in the cleaving step. The cleaving method according to item.

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