JP2007250620A - Substrate dividing method, and manufacturing method of electro-optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate dividing method for suitably dividing a substrate even when a conductive pattern is formed on the dividing line, and to provide a manufacturing method of an electro-optical device. <P>SOLUTION: For dividing a substrate 10 by radiating a laser beam LB along the dividing lines L1, L2 of the substrate 10 and then cooling the irradiating area of the laser beam LB with a cooling agent LC, the substrate 10 is placed on a stage 4 with the rear surface 10b upside after a protection film 5 is adhered in the front surface side 10a of the substrate 10, and the laser beam LB is irradiated to the rear surface 10b of the substrate 10 from the upper side under this condition. Therefore, even when conductive patterns 11, 12 are formed on the cracking and dividing lines L1, L2 on the front surface 10a of the substrate 10, the substrate 10 can surely be heated with the laser beam LB and can also be divided suitably. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a substrate cleaving method for cleaving a substrate by locally irradiating and cooling the substrate, and a method for manufacturing an electro-optical device using this method.

As a method suitable for cleaving a substrate made of a brittle material such as glass, the laser beam is irradiated locally along the planned cutting line of the substrate, and then the irradiated region of the laser beam is locally cooled for cleaving. A method of cleaving a substrate along a planned line has been proposed. Such a cleaving method is a method in which a substrate is cleaved by moving a laser irradiation position and a cooling position while causing cracks in the substrate by local laser irradiation and cooling (see Patent Document 1).
US Pat. No. 5,609,284

  However, substrates (electro-optical device substrates) used in electro-optical devices such as liquid crystal devices, electroluminescence devices, and plasma display devices are usually cleaved into a predetermined size after forming signal lines and electrodes on the surface of a large substrate. Therefore, a conductive pattern formed simultaneously with a signal line, an electrode, and the like is often formed on the cleaving cutting line. For this reason, when laser irradiation is performed on the surface of the substrate along the planned cutting line, part of the irradiated laser light is reflected by the conductive pattern, and heat applied to the surface of the substrate is transferred to the substrate. It may not be transmitted enough to the inside and back of the. When such a situation occurs, the thermal stress at the inside and the back surface becomes weaker than the front surface of the substrate, and the substrate cannot be completely cleaved from the front surface to the back surface. As a result, there is a problem that only the surface of the substrate is cleaved and microcracks are generated in the substrate. Such a microcrack is not preferable because it becomes a starting point and causes the substrate to crack.

  In view of the above problems, an object of the present invention is to provide a method for cleaving a substrate and a method for manufacturing an electro-optical device that can cleave the substrate even when a conductive pattern is formed on the cleaving line. There is to do.

  In order to solve the above-mentioned problem, in the present invention, after irradiating a laser beam along a planned cutting line of a substrate, a method of cutting the substrate along the planned cutting line by cooling the irradiation region of the laser beam The conductive pattern is formed on at least a part of the planned cutting line on the front surface and the back surface of the substrate, and when the substrate is irradiated with the laser beam, the laser beam is applied to the substrate It irradiates from the back surface of.

  In this invention, after irradiating a laser beam along the planned cutting line of a board | substrate, the irradiation area | region of the said laser beam is cooled, a crack is generated along the said planned cutting line, and a board | substrate is cut. Here, a conductive pattern is formed on the planned cutting line on the surface of the substrate, but since the laser beam is irradiated from the back surface of the substrate, the irradiated laser beam is reflected by the conductive pattern before heating the substrate. This does not happen. Therefore, the substrate can be heated uniformly from the back surface side to the front surface side, and thermal stress can be generated, so that the substrate can be completely cleaved from the back surface to the front surface. Therefore, since it is possible to prevent microcracks from occurring on the substrate, it is possible to avoid a situation where the substrate cracks starting from the microcracks.

  In the present invention, when the substrate is irradiated with the laser beam, a protective film is applied to the front side of the substrate, and then the laser beam is placed on the stage with the back side facing up. It is preferable to employ a method of irradiating from the top toward the back surface of the substrate. With this configuration, even when the substrate is placed on the stage with the front side facing downward, the stage does not contact the surface of the substrate because the protective film is applied to the surface of the substrate. Therefore, it is possible to prevent the signal lines and electrodes formed on the substrate from being damaged due to contact with the stage. Moreover, when the structure which mounts a board | substrate on a stage is employ | adopted, even if the thickness of a board | substrate is as thin as about 0.5 mm, there exists an advantage that it does not bend.

  In this invention, the said protective film may be affixed on at least one part of the position which overlaps with the said cutting plan line, and at least one part of the peripheral part of the said board | substrate among the surfaces of the said board | substrate. In this case, it is preferable that the film base of the protective film is irradiated with the laser beam and cooled in a state where a cut is made along the planned cutting line. If comprised in this way, it will not become a hindrance when a protective film cleaves a board | substrate.

  In this invention, it is preferable to affix the said protective film in the position which avoided the said cutting planned line among the surfaces of the said board | substrate. If the protective film is stuck on the planned cutting line and air bubbles are present between the protective film and the substrate, the air bubbles may expand when the substrate is heated by irradiating the laser beam. . In such a state, if the protective film is peeled off, the adhesive will stick to the side of the substrate and cause problems such as remaining, but if you attach the protective film to a position that avoids the planned cutting line, Such a situation can be avoided.

  In this invention, it is preferable to affix the said protective film on the said board | substrate with the adhesive provided with UV curability. If comprised in this way, when peeling a protective film, since the adhesive force of an adhesive declines by UV irradiation, an adhesive does not remain on a board | substrate.

  In the present invention, the protective film is preferably transparent or translucent. With this configuration, when a protective film is pasted at the position where the alignment mark is formed on the surface of the substrate, even if the alignment mark is made of either light-shielding or translucent material, The alignment mark can be visually recognized when viewed from the back side. Therefore, when the substrate is placed on the stage, the alignment of the substrate and the stage can be performed with reference to the alignment mark.

  In the present invention, when irradiating the substrate with the laser beam, the substrate is supported with the back side facing down on a substrate support that opens the lower side of the planned cutting line, and in this state the laser is supported. You may employ | adopt the method of irradiating a beam toward the back surface of the said board | substrate from the downward direction.

  The substrate cleaving method according to the present invention can be applied to a method for manufacturing an electro-optical device. In this case, after forming at least signal lines and electrodes on the surface side of the large electro-optical device substrate as the substrate, the large electro-optical device substrate is cleaved into a predetermined size. Perform the cleaving method.

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

[Clearance target]
FIGS. 1A and 1B are explanatory diagrams of an electro-optical device in which a substrate to be cleaved according to the present invention is used. 2A and 2B are a plan view showing the configuration of the front surface of the substrate to be cleaved according to the present invention, and a bottom view showing the configuration of the back surface.

  The cleaving method to which the present invention is applied can be used, for example, in the method for manufacturing the electro-optical device shown in FIGS. First, the electro-optical device 100p shown in FIG. 1A is an organic electroluminescence device. On the element substrate 10p used in the electro-optical device 100p, a plurality of scanning lines 103p and scanning lines 103p are extended. A plurality of data lines 106p extending in a direction intersecting the direction, a plurality of common power supply lines 23p parallel to the data lines 106p, and a pixel region corresponding to an intersection of the data line 106p and the scanning line 103p 15p. A data side driving circuit 101p including a shift register, a level shifter, a video line, and an analog switch is configured for the data line 106p, and a scanning side driving circuit 104p including a shift register and a level shifter is configured for the scanning line 103p. Has been. Each pixel region 15p holds a first TFT 31p to which a scanning signal is supplied to the gate electrode via the scanning line 103p, and an image signal supplied from the data line 106p via the first TFT 31p. The storage capacitor 33p, the second TFT 32p to which the image signal held by the storage capacitor 33p is supplied to the gate electrode, and the common supply line 23p when electrically connected to the common power supply line 23p via the second TFT 32p. An electroluminescence element 40p into which a drive current flows from the electric wire 23p is configured. In the electro-optical device 1p configured as described above, the image signal supplied from the data line 106p via the first TFT 31p is held in the holding capacitor 33p. Therefore, even if the first TFT 31p is turned off, the second signal is supplied. The gate electrode 31p of the TFT 32p is held at a potential corresponding to the image signal. Therefore, since the drive current continues to flow from the common power supply line 23p to the light emitting element 40p, the light emitting element 40p continues to emit light and can display an image.

  The electro-optical device 100r shown in FIG. 1B is a liquid crystal device. On the element substrate 10r used in the electro-optical device 100r, a pixel electrode 9a, a pixel electrode 9a, A pixel switching TFT 30 for controlling the pixel electrode 9 a is formed, and a data line 106 a for supplying a pixel signal is electrically connected to the source of the TFT 30. Pixel signals S1, S2,... Sn written to the data line 106a are supplied line-sequentially in this order. Further, the scanning line 103a is electrically connected to the gate of the TFT 30, and the scanning signals G1, G2,... Gm are applied to the scanning line 103a in a pulse-sequential manner in this order at a predetermined timing. It is configured. The pixel electrode 9a is electrically connected to the drain of the TFT 30, and by turning on the TFT 30 for a certain period, the pixel signals S1, S2,... Sn supplied from the data line 106a are supplied to each pixel. Write at a predetermined timing. In this way, the pixel signals S1, S2,... Sn at a predetermined level written to the liquid crystal through the pixel electrode 9a are held for a certain period with the counter electrode formed on the counter substrate (not shown). Is done. Here, in order to prevent the held pixel signal from leaking, a holding capacitor 70 may be added in parallel with the liquid crystal capacitor formed between the pixel electrode 9a and the counter electrode.

  As described above, a large number of signal lines and electrodes are formed on the element substrates 10p and 10r used in the electro-optical devices 100p and 100r. For example, as shown in FIG. 2A, such signal lines and electrodes are formed on a surface 10 of a large substrate 10 on which a large number of element substrates 10p and 10r can be obtained by using a semiconductor process or the like. It is formed. The large substrate 10 is divided along the planned cutting lines L1 and L2, and is divided into element substrates 10p and 10r.

Here, the substrate 10 is made of a brittle material such as glass. As will be described later, after the laser beam is irradiated along the planned cutting lines L1 and L2 of the substrate 10, the irradiation region of the laser beam is cooled and cleaved. It is cleaved by generating a crack along the planned lines L1 and L2. Here, on the surface 10a of the substrate 10, the above-described elements, signal lines, electrodes, and the like are formed, and conductive materials such as alignment marks, inspection wirings, test patterns, etc. are overlapped with the planned cutting lines L1, L2. The patterns 11 and 12 are formed of a metal film such as aluminum or an ITO film. On the other hand, as shown in FIG. 2B, on the back surface 10b of the substrate 10, as well as the above elements, signal lines, electrodes, etc., conductive patterns such as alignment marks, inspection wirings, test patterns, etc. Is not formed at all. Therefore, in this embodiment, the substrate 10 is cleaved by the following method.

[Embodiment 1]
3 (a) and 3 (b) are an explanatory diagram showing a configuration of a main part of the cleaving apparatus used in the cleaving method according to Embodiment 1 of the present invention, and a cross-sectional view of a state where the substrate is placed on the stage. is there. FIG. 4 is an explanatory view showing a state in which a protective film is pasted on the surface of the substrate when performing the cleaving method according to Embodiment 1 of the present invention.

3 (a) and 3 (b), the cleaving apparatus 1 used in this embodiment is for irradiating a laser beam LB along the planned cutting lines L1 and L2 of the substrate 10 to locally heat the substrate 10. A laser irradiation device 2; a cooling device 3 for injecting a coolant LC toward a region heated locally on the substrate 10 by the laser irradiation device 2; And a stage 4 for adsorbing and holding the substrate. Here, the stage 4 includes a driving device (not shown) that moves the substrate 10 relative to the laser irradiation device 2 and the cooling device 3 as indicated by arrows Y and Z. The coolant LC may be either liquid or gas, and water, alcohol, cooled nitrogen gas, or the like is used. Further, dry ice may be used as the coolant LC. As the laser irradiation device 2, a CO ₂ laser or the like is used.

  In cleaving the substrate 10 using the cleaving apparatus 1 configured as described above, in the present embodiment, first, in FIG. As shown in the region, the protective film 5 is attached via an adhesive, and in this state, the substrate 10 is placed on the stage 4 with the back surface 10b facing upward. Air bubbles are prevented from entering when the protective film 5 is applied. If bubbles exist in the region overlapping with the planned cutting lines L1 and L2, the bubbles expand when the substrate 10 is heated by irradiating the laser beam LB in the next step. This is because the agent remains attached to the substrate 10 side. The protective film 5 is transparent or translucent.

  Next, the laser beam LB is irradiated from above toward the back surface 10b of the substrate 10, and the stage 4 is moved to move the laser irradiation device 2 and the substrate 10 relative to each other so that the laser beam LB is cleaved. It moves along the planned lines L1 and L2. At that time, the cooling device 3 also moves relative to the substrate 10 so as to follow the laser irradiation device 2.

  As a result, the substrate 10 can be cleaved because cracks occur along the planned cutting lines L1 and L2.

  After that, the protective film 5 is peeled off. Here, if what is called a so-called UV curable film is used as the protective film 5, the adhesive material formed on the film substrate made of polyester, polyolefin, vinyl chloride or the like has UV curable properties. When the protective film 5 is peeled off, the adhesive strength of the adhesive material is reduced if UV is irradiated, so that the adhesive material does not remain on the substrate 10.

As described above, according to the cleaving method of this embodiment, the conductive patterns 11 and 12 are formed on the cleaved lines L1 and L2 on the surface 10a of the substrate 10, but the laser beam LB is applied to the back surface of the substrate 10. Since irradiation is performed from 10b, a situation in which the irradiated laser beam LB is reflected by the conductive patterns 11 and 12 before heating the substrate 10 does not occur. Therefore, the substrate 10 can be heated uniformly from the back surface 10b side to the front surface 10a side, and a thermal stress can be generated reliably, so that the substrate 10 can be completely cleaved from the back surface 10b to the front surface 10a. Therefore, since it is possible to prevent microcracks from occurring on the substrate 10, it is possible to avoid a situation in which the substrate 10 is cracked starting from the microcracks.

  In this embodiment, the substrate 10 is placed on the stage 4 with the surface 10a side facing downward. However, since the protective film 5 is attached to the surface of the substrate 10, the stage 4 is connected to the surface 10a of the substrate 10. Do not touch. Therefore, it is possible to prevent signal lines and electrodes formed on the substrate 10 from being damaged due to contact with the stage 4.

  In this embodiment, since the protective film 5 is transparent or translucent, the alignment mark is light-shielding or translucent when the protective film 5 is pasted on the surface 10a of the substrate 10 where the alignment mark is formed. The alignment mark can be visually recognized when the substrate 10 is viewed from the back surface 10b side. Therefore, when the substrate 10 is placed on the stage 4, the alignment between the substrate 10 and the stage 4 can be performed based on the alignment mark.

  Furthermore, in this embodiment, since the substrate 10 is supported by the stage 4, there is an advantage that even if the thickness of the substrate 10 is as thin as about 0.5 mm, it does not bend.

  In addition, in this form, since the protective film 5 was affixed on the whole surface 10a of the board | substrate 10, the cutting planned lines L1 and L2 and the protective film 5 have overlapped. In such a case, it is preferable that the film base material of the protective film 5 is cut along the planned cutting lines L1 and L2. If comprised in this way, it will not become a hindrance when the protective film 5 cleaves the board | substrate 10. FIG.

[Modification of Embodiment 1]
5A, 5B, and 5C are explanatory views showing a state in which a protective film is pasted on the surface of the substrate when the substrate is cleaved by the cleaving method according to the modification of the first embodiment of the present invention. It is.

  In the embodiment described with reference to FIG. 4, the protective film 5 is pasted on the entire surface 10 a of the substrate 10, but as shown by the hatched area rising to the right in FIG. 5A, of the surface 10 a of the substrate 10, You may affix the protective film 5 (UV cured film) only to the area | region and board | substrate peripheral part along the cutting line L1, L2. By sticking the protective film 5 in this manner, the substrate surface can be protected with a small amount of the protective film, so that the cost can be reduced. In addition, as shown by the hatched area rising to the right in FIG. 5B, the protective film 5 may be pasted so that the protective film 5 is positioned at the four corners of the substrate after cleaving. Also in such a case, if the film base material of the protective film 5 is cut along the planned cutting lines L <b> 1 and L <b> 2, the protective film 5 does not hinder the substrate 10 from being cut.

  Moreover, in the form shown in FIG. 4 and FIG. 5 (a), the protective film 5 is pasted at a position that overlaps the planned cutting lines L1 and L2. However, as shown in FIG. The protective film 5 (UV curable film) may be pasted only on the area of the ten surfaces 10a that avoids the split lines L1 and L2. As shown in FIGS. 4 and 5 (a), 5 (b), when the protective film 5 is pasted on the cutting lines L1 and L2, bubbles exist between the protective film 5 and the substrate 10. If so, bubbles may swell when the substrate 10 is heated by irradiation with the laser beam LB. If the protective film 5 is peeled off in such a state, the adhesive will stick to the substrate 10 side and cause a problem such as remaining, but as shown in FIG. If the protective film 5 is affixed at a position where L1 and L2 are avoided, such a situation can be avoided.

[Embodiment 2]
6 (a) and 6 (b) are explanatory views showing the configuration of the main part of the cleaving apparatus used in the cleaving method according to Embodiment 2 of the present invention, and a cross-sectional view of a state in which the substrate is placed on the stage. is there. The basic configuration of the present embodiment is the same as that of the first embodiment, and therefore, common portions will be described with the same reference numerals.

6 (a) and 6 (b), the cleaving apparatus 1 used in this embodiment is irradiated with a laser beam LB along the planned cleaving lines L1 and L2 of the substrate 10 in the same manner as in the first embodiment. Then, the laser irradiation device 2 for locally heating the substrate 10 and the coolant LC is jetted toward the region heated locally on the substrate 10 by the laser irradiation device 2, and this region is A cooling device 3 for locally cooling and a stage 4 for sucking and holding the substrate 10 are provided. Here, the stage 4 includes a driving device (not shown) that moves the substrate 10 relative to the laser irradiation device 2 and the cooling device 3 as indicated by arrows Y and Z. The coolant LC may be either liquid or gas, and water, alcohol, cooled nitrogen gas, or the like is used. Further, dry ice may be used as the coolant LC. As the laser irradiation device 2, a CO ₂ laser or the like is used.

  In the present embodiment, unlike the first embodiment, the laser irradiation device 2 and the cooling device 3 are arranged at a position below the stage 4. For this reason, the laser irradiation device 2 emits the laser beam LB upward, and the cooling device 3 injects the coolant LC upward.

  Further, in this embodiment, the stage 4 is provided with a groove 40 penetrating the stage 4 in the vertical direction at a position overlapping the planned cutting lines L1 and L2 with the substrate 10 placed on the upper surface thereof. .

  In cleaving the substrate 10 using the cleaving apparatus 1 configured as described above, in this embodiment, the substrate 10 is placed on the stage 4 with the back surface 10b facing downward. At this time, the substrate 10 is arranged at a predetermined position on the stage 4 so that the planned cutting lines L1 and L2 and the groove 40 overlap so that the lower side of the planned cutting lines L1 and L2 is open.

  Next, the laser irradiation device 2 irradiates the laser beam LB from below toward the back surface 10b of the substrate 10 and moves the stage 4 to relatively move the laser irradiation device 2 and the substrate 10 so that the laser beam LB is emitted. The substrate 10 is moved along the planned cutting lines L1 and L2. At that time, the cooling device 3 also moves relative to the substrate 10 so as to follow the laser irradiation device 2.

  As a result, the substrate 10 can be cleaved because cracks occur along the planned cutting lines L1 and L2. Here, although the conductive patterns 11 and 12 are formed on the planned cutting lines L1 and L2 on the front surface 10a of the substrate 10, since the laser beam LB is irradiated from the back surface 10b of the substrate 10, the irradiated laser beam LB is irradiated. Is not reflected by the conductive patterns 11 and 12 before the substrate 10 is heated. Therefore, the substrate 10 can be heated uniformly from the back surface 10b side to the front surface 10a side, and a thermal stress can be generated reliably, so that the substrate 10 can be completely cleaved from the back surface 10b to the front surface 10a. Therefore, since it is possible to prevent microcracks from occurring on the substrate 10, it is possible to avoid a situation in which the substrate 10 is cracked starting from the microcracks.

  Further, in this embodiment, since the substrate 10 is supported by the stage 4, there is an advantage that even if the thickness of the substrate 10 is as thin as about 0.5 mm, it does not bend.

  Further, since the substrate 10 is placed on the stage 4 with the front surface 10a facing upward, it is possible to prevent the signal lines and electrodes formed on the substrate 10 from being damaged by contact with the stage 4.

[Modification of Embodiment 2]
In the second embodiment, the stage 4 is used to hold the substrate 10. However, as long as the lower side of the cutting lines L1 and L2 can be opened, not only the stage 4 but also a roller or the like. You may use the board | substrate support using this.

(A), (b) is explanatory drawing of the electro-optical apparatus in which the board | substrate used as the cutting object of this invention is used. (A), (b) is the top view which shows the structure of the surface of the board | substrate used as the cutting object of this invention, and the bottom view which shows the structure of a back surface. (A), (b) is explanatory drawing which shows the structure of the principal part of the cleaving apparatus used for the cleaving method which concerns on Embodiment 1 of this invention, and sectional drawing of the state which mounted the board | substrate on the stage. It is explanatory drawing which shows the state which stuck the protective film on the surface of the board | substrate when performing the cleaving method which concerns on Embodiment 1 of this invention. (A), (b), (c) is explanatory drawing which shows the state which stuck the protective film on the surface of the board | substrate with another form, when cleaving a board | substrate with the cleaving method which concerns on Embodiment 1 of this invention. is there. (A), (b) is explanatory drawing which shows the structure of the principal part of the cleaving apparatus used for the cleaving method which concerns on Embodiment 2 of this invention, and sectional drawing of the state which mounted the board | substrate on the stage.

Explanation of symbols

1 .... Cleaving device 2 .... Laser irradiation device 3 .... Cooling device 4 .... Stage 5 .... Protective film 10 .... Large substrate 10a ...... Front surface of substrate 10b ...... Back side of substrate , 11, 12... Conductive pattern, L 1, L 2, scheduled cutting line, LB, laser beam, LC, coolant

Claims (9)

In a method of irradiating a laser beam along a planned cutting line of the substrate, then cooling the irradiation region of the laser beam and cutting the substrate along the planned cutting line,
Of the front and back surfaces of the substrate, a conductive pattern is formed on at least a part of the planned cutting line on the front surface,
A substrate cleaving method, comprising: irradiating the substrate with the laser beam from the back surface of the substrate.   After applying a protective film on the front surface side of the substrate, the laser beam is irradiated from above toward the back surface of the substrate in a state where the substrate is placed on a stage with the back surface facing upward. The method for cleaving a substrate according to claim 1.   The method for cleaving a substrate according to claim 2, wherein the protective film is pasted on at least a part of the surface of the substrate that overlaps the planned cutting line and at least a part of a peripheral part of the substrate. .   4. The method of cleaving a substrate according to claim 3, wherein the film base of the protective film is irradiated with the laser beam and cooled in a state where a cut is made along the planned cutting line.   The method for cleaving a substrate according to claim 2, wherein the protective film is pasted at a position on the surface of the substrate that avoids the planned cutting line.   The method for cleaving a substrate according to any one of claims 2 to 5, wherein the protective film is attached to the substrate with an adhesive having UV curable properties.   The substrate cleaving method according to claim 2, wherein the protective film is transparent or translucent.   The substrate is supported with the back side facing downward on a substrate support that opens the lower side of the planned cutting line, and in this state, the laser beam is irradiated from below to the back side of the substrate. The method for cleaving a substrate according to claim 1.   An electro-optical device manufacturing method using the substrate cleaving method according to claim 1, wherein at least a signal line and an electrode are provided on a surface side of a large electro-optical device substrate as the substrate. After forming the substrate, the large electro-optical device substrate is cleaved into a predetermined size.

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