JP5784273B2 - Laser processing method, cutting method, and method for dividing structure having multilayer substrate - Google Patents

Description

The present invention relates to a method of processing an object to be processed, particularly an object having a flat shape such as a substrate, efficiently and with high quality using an ultrashort pulse laser having a wavelength that is transparent to the object.
The present invention also relates to a dividing method using a laser beam of a structure having a multilayer substrate having a structure in which at least two substrates are arranged in parallel and a spacer is inserted between the substrates. It is suitable for dividing a flat panel display panel using a glass substrate such as a liquid crystal display panel or a plasma display panel.

In the electronics industry, miniaturization of semiconductor devices such as CPUs, DRAMs, and SRAMs has been progressing year by year, and the integration of internal circuits has been increased accordingly. The structure of these devices is formed with a highly integrated circuit pattern on a semiconductor substrate such as a silicon wafer. In order to harvest a large number of chips from a semiconductor wafer, it is necessary to minimize the area required for dividing the chips. For this purpose, it is desired that the processed removal is less scattered in the scribing process. In a cutting process of a glass substrate such as a liquid crystal display, it is desired that the glass substrate can be accurately divided into predetermined dimensions. In these division processes, it is necessary to perform removal processing under conditions that do not cause thermal damage or mechanical damage to the periphery of the processing portion. For this reason, a narrow pulse of nanosecond pulse or less is used. In processing using an ultrashort pulse laser, the generation of a thermally altered layer can be reduced, and even a transparent material for that wavelength can be processed by nonlinear light absorption typified by multiphoton absorption. This is a well-known technique.
A method of processing a transparent body using laser light of ultrashort pulse oscillation is well known from Patent Document 2, and further, it is described in Patent Document 3 that the object to be processed is focused on the back surface of the substrate to perform laser processing. Yes.

  When UV laser light with a large surface absorption is irradiated, plasma is generated from the irradiated surface, and the laser light is absorbed there, so that the efficiency of laser energy utilization is reduced and the surroundings are irradiated by radiation from the plasma. In some cases, the surrounding device characteristics may be affected. Therefore, as a scribing process for dividing a semiconductor substrate, a glass substrate for a thin film transistor, etc. into a predetermined size, a laser beam is focused on the processing surface from the surface opposite to the surface to be cut (processing surface). Patent Document 3 describes a method of machining a cut on a machined surface. In this method, since laser ablation processing is performed by condensing the laser beam on the surface opposite to the laser beam incident side, there is a drawback that the depth of the processing groove cannot be obtained sufficiently. If the groove depth is not sufficiently deep, the separation force along the groove increases the bending force required for braking, and the groove may not be divided along the scribe line. If the depth of the processed groove is sufficient, it can be divided along the scribe line with less stress.

  On the other hand, in manufacturing a liquid crystal display device, there is a step of cutting a large glass substrate constituting a panel. On the panel surface of the liquid crystal display device, at least two glass plates are arranged in parallel, and wirings such as a color filter, a liquid crystal, a thin film transistor (TFT), and a control electrode necessary for the display device are provided therebetween. In the manufacturing process, these glass plates are manufactured by simultaneously manufacturing a large number of display devices by using a glass larger than the size of the final display device, thereby simultaneously manufacturing a large number of display panels to improve efficiency. Therefore, it is necessary to individually cut from a large glass substrate on which a large number of large panels are finally formed in accordance with the panel size of the product. A conventional method of cutting a glass plate uses a diamond blade, a carbide blade or the like to cut a glass surface along a desired line to be cut to provide a scribe line, and then apply stress to the scribe line. A method of breaking along and separating along the scribe line in addition to a perpendicular direction, or scanning a laser beam along a desired line to be cut, heating, generating thermal stress on the glass substrate, There is a method of breaking and dividing. In this case, the glass plate is irradiated with a laser wavelength having a large absorption rate, is locally heated, is then forcibly cooled, and is divided from the irradiation position.

  When the display element is inserted between two glass plates and the periphery of the glass is sealed with a sealing agent and then divided into individual display panels, scribing is performed one side at a time from both sides of the two glass plates, A method of cutting is performed. In order to make a cut with a diamond blade, after scribing on one side, flip the two-sided glass plate upside down and scribing on the other side, then split the two-layer glass plate together It becomes. In recent years, the size of the glass used for the panel tends to become larger due to the trend of increasing the size of the display panel. Therefore, the conveying device for large glass plates for manufacturing becomes complicated, the reversing mechanism becomes large and expensive. Equipment. Therefore, the method of scribing from one side without turning the glass plate is a practically effective production method. Patent Document 4 discloses a proposal in which an ultraviolet laser is irradiated on each glass surface from one side of a two-ply glass and scribing is performed on the surfaces of both glass plates having a two-ply structure. In this method, the glass is transparent to the laser beam, and when the laser beam is irradiated from the upper glass side, it is necessary that the ultraviolet laser beam reaches the lower glass surface through the upper glass. . Therefore, if there is a metal film used for the metal wiring on the upper surface of the lower glass or the inner surface of the upper glass plate, the laser beam is irradiated to damage the metal film, or it is blocked by the metal film and guides the laser beam to the lower glass. It becomes difficult. When there are inclusions between the two glasses in this way, it is difficult to scribe the lower glass plate through the upper glass plate by laser beam irradiation from one side.

US Reissue Patent No. 37585 Specification JP 2002-205179 A JP 2004-351466 A JP 2005-132694 A JP-A-8-64556

The problem to be solved is that when a high-precision machining is performed on the surface opposite to the incident side (back surface) using an ultrashort pulse laser beam having a wavelength that is transparent to the workpiece, A small diameter beam is provided in the laser beam traveling direction over a range longer than the focal depth of the focal point.
A further problem is to provide a method in which the structure can be divided by irradiating laser light only from one substrate surface side of the structure having a multilayer substrate. Another object of the present invention is to provide a dividing method in which a metal thin film is exposed in a structure having a metal thin film between two substrates. In addition, in the case of having a sealing portion between two substrates and forming an electronic component inside the sealing portion, a structure dividing method that can lead out wiring from the electronic component to the outside of the sealing portion Is to provide.

  The above-mentioned problem is solved by generating a self-focusing action inside the workpiece and making the machining distance in the traveling direction of the laser beam much larger than that of normal ablation while keeping the machining width of the laser beam small.

  In order to solve the above-mentioned problems, the present invention is a laser processing method, wherein an ultrashort pulse laser beam having a wavelength that is transparent to an object to be processed having a first surface and a second surface is transmitted through a focusing means. The laser beam is condensed so that a beam waist position of the collected laser beam is formed between the first surface and the second surface of the workpiece from the first surface side. By irradiating and forming a condensing channel in the traveling direction of the laser beam by the self-focusing action by the ultrashort pulse high peak laser beam propagation inside the object to be processed, the condensing channel portion is formed on the second surface. A reaching cavity or a cavity reaching the vicinity of the second surface is formed. Thereby, the processing distance in the laser beam traveling direction can be made larger than that of normal ablation processing.

  In addition, a raised structure having a low mechanical strength is formed in which the vicinity of the intersection with the second surface in the laser beam traveling direction is raised higher than the peripheral surface. The condensing channel is formed up to the second surface, whereby the cavity is formed up to the second surface. Further, the condensing channel is formed from the first surface to the second surface, so that the cavity is formed from the first surface to the second surface. Further, the condensing channel is formed from the first surface to the inside of the processed object, so that the cavity is formed from the first surface to the inside of the processed object. By each, the processing distance in the laser beam traveling direction can be made larger than that of normal ablation processing.

Further, the object to be processed has a multilayer structure in which two or more flat objects of the same kind or different materials overlap each other. Thereby, two or more objects can be processed simultaneously.
Moreover, the length of the condensing channel due to the self-focusing action generated in the object to be processed is changed by installing another object transparent to the laser wavelength on the first surface side of the object to be processed. It is characterized by doing. Thereby, the processing distance in the laser beam traveling direction can be adjusted.
In addition, by installing another object transparent to the laser wavelength on the first surface side of the object to be processed, the condensing channel by the self-focusing action generated in the object to be processed is provided on the first surface. It is made to reach. Thereby, it is possible to process up to the front side of the substrate.

In addition, a spatial overlap of the cavities is provided by relatively moving the ultrashort pulse laser beam condensed inside the object to be processed by the condensing unit at an arbitrary speed along a cutting direction. It is characterized by. Further, the ultrashort pulse laser beam condensed inside the object to be processed by the condensing means is relatively moved at an arbitrary speed along the cutting direction, so that the cavities are spatially separated. It is characterized by. In each case, a cutting line can be created on the workpiece, and since the machining distance in the laser beam traveling direction is large, the workpiece can be cut with a small bending stress.
Further, the object to be processed is an object having a planar shape, and the condensed laser light of the ultrashort pulse laser is incident at an angle with respect to the normal direction of the first surface of the object to be processed, The condensed laser beam is rotated while giving the inclination of the angle to perform circular scanning, and the processing surface is inclined and processed. Thereby, a circular cutting line can be created.
Further, the present invention is characterized in that the relative movement is performed a plurality of times and the height of the beam waist of the laser beam is changed during each relative movement. Thereby, since a cavity is formed deeply in the workpiece, it is possible to perform processing from partial cutting to full cutting.

On the other hand, the present invention is a method for cutting an object to be processed, wherein the object to be processed is cut with a small amount of stress along a processed portion after laser processing of the object to be processed is performed. Thereby, the workpiece can be divided along the cutting line correctly.
Also, there is provided a substrate cutting method for a liquid crystal display panel, wherein the liquid crystal display panel has a laminated structure of a first substrate and a second substrate, and is mounted on the surface of the second substrate on the first substrate side. Irradiating a laser so that a beam waist is formed in the first substrate from the side of the first substrate by applying, adhering or closely adhering a material opaque to the laser wavelength on the component; In the irradiation, the laser beam that has passed through the first substrate is prevented from damaging the component.

In addition, the present invention provides a method for dividing the first and second substrates and the structures disposed in parallel with a spacer partially interposed therebetween. The method is as follows.
An ultrashort pulse laser having a wavelength that is transparent on the first and second substrates and having a pulse width of 100 ps or less is condensed through a condensing unit, and a beam waist position from the outside of the first substrate is the surface of one of the substrates or Irradiated to form inside, a condensing channel is formed in the traveling direction of the ultrashort pulse laser beam by the self-focusing action by propagation of the ultrashort pulse laser, thereby forming a cavity in the condensing channel portion A scribe line forming step of forming a scribe line by relatively moving the ultrashort pulse laser beam, and then a substrate cutting step of cutting the substrate on which the scribe line is formed along the scribe line. Have. Since processing can be performed by irradiating a laser beam from only one surface of a structure having a multilayer substrate, particularly a two-layer substrate, the equipment can be simplified.
Further, the present invention is characterized in that the scribe line forming step includes the following step A, and the substrate cutting step includes the following step C.
Further, the present invention has the following A and B steps in the scribe line forming step, and is performed in the order of A, B or B, A, and the substrate cutting step has the following C and D steps, It carries out in order of C and D, It is characterized by the above-mentioned. As a result, a portion of the second substrate that does not oppose the first substrate can be formed, so that the control circuit can be formed on the inner surface of the second substrate or on the upper surface of the second substrate. Can be made thinner.

Step A: Transmitting the first substrate, condensing the ultrashort pulse laser so that the beam waist comes to the second substrate, forming a first scribe line on the second substrate, and further forming the first beam waist on the first substrate. The second scribe line is formed on the first substrate by focusing the light so as to be located on the substrate and relatively moving the ultrashort pulse laser at the same plane position as the first scribe line.
Step B: Condensing the ultrashort pulse laser so that the beam waist is positioned on the first substrate, and relatively moving the ultrashort pulse laser light in parallel with the second scribe line at a predetermined distance. Thus, a third scribe line is formed on the first substrate.
Step C: The structure is divided by cutting the second and first substrates along the first and second scribe lines.
Step D: By cutting the first substrate along the third scribe line, the portion of the third scribe line is removed from the second scribe line of the first substrate.

  Furthermore, the structure has a metal thin film on a surface of the second substrate facing the first substrate side, and the spacer is a sealing material, and the first and second substrates and the sealing material An electronic component is formed in the space, and the metal thin film exists between the inside and the outside of the space, and the metal thin film is electrically connected to the electronic component. Since the metal thin film crosses the sealing body and is electrically connected to the electronic component formed inside the sealing body, the metal thin film can be used as a wiring. The electronic component can be wired outside the sealing portion.

  Furthermore, the present invention is a laser processing apparatus, comprising an ultrashort pulse laser generator, a rotating mirror that rotates by deflecting a pulse laser beam generated from the ultrashort pulse laser generator at a constant angle, and is deflected A condensing lens that rotates in synchronization with the rotating mirror so that the optical path and optical axis of the pulse laser beam coincide with each other, and the focal point draws a circular locus by the rotation, and moves the condensing lens along the optical axis direction And means for mounting a processed object. With this configuration, it is possible to make a cutting line in a circular shape in the workpiece, and it is possible to cut it into a circular shape along the cutting line.

Due to the occurrence of the self- focusing action, a condensing channel is formed in a traveling direction of the laser beam over a distance longer than the beam waist, a cavity is formed in the condensing channel portion, and a cavity reaching the second surface in the condensing channel portion Alternatively, since the cavity reaching the vicinity of the second surface is formed, the processing distance in the laser beam traveling direction can be made larger than that of normal ablation processing.

Embodiments of the present invention will be described below. FIG. 1 is a diagram showing an embodiment of a processing method according to the present invention. A laser beam (beam) 2, which is an ultrashort pulse 15 output from the ultrashort pulse laser generator 1, is collimated by a collimator (not shown), is incident on a condensing means such as a condensing lens 3, and the focused laser beam 5 is incident from the front surface 45 of the workpiece 4. The ultrashort pulse laser is a laser having a pulse width of 100 ps or less. Examples of the workpiece 4 include a dielectric material such as glass, sapphire, or diamond, or a semiconductor material such as silicon or gallium nitride. The object 4 to be processed is preferably a flat object such as a substrate. For this reason, hereinafter, the workpiece 4 may be referred to as a substrate. The laser is selected to have a wavelength that is transparent to the workpiece. Here, transparent does not necessarily mean that 100% of light is transmitted. The case where the laser beam can be transmitted to some extent is also included. For example, when the object to be processed is a silicon substrate, it may be an infrared region having a wavelength of 1 μm to 2 μm. Examples of the laser medium include titanium sapphire crystal (center wavelength 780 nm), erbium-doped fiber, yttrium-doped fiber, Nd: YAG crystal, Nd: YVO ₄ crystal, Nd: YLF crystal, and the like. When the glass substrate is an object to be processed, the laser medium is preferably a titanium sapphire crystal (center wavelength 780 nm).
Note that the front surface is a surface on which laser light is incident, and the surface on the opposite side is referred to as a back surface. The focused laser beam 5 forms a beam waist 6 which is a condensing point inside the workpiece 4. A focused laser beam 5 is irradiated onto the workpiece 4, and the beam waist 6 is aligned with an appropriate position inside the workpiece from the front surface 45 to the back surface 44 to irradiate the beam.

When the energy, wavelength and pulse width of the focused laser beam 5 and the focal length and focusing position of the condenser lens 3 are adjusted, and the ultrashort pulse is condensed at a high power density inside the workpiece 4, the beam waist 6 A self-focusing action based on the Kerr effect is generated in the direction of travel from the direction of travel, and a narrow beam propagation channel 8 having a diameter of about the beam waist 6 is formed. In FIG. 1, when the irradiation condition is set so that the laser beam waist 6 is formed in the thickness 7 of the workpiece 4 from the back surface 44 toward the front surface, the incident focused laser beam 5 is emitted from the beam waist 6. In a region where the power density is weak and the self-focusing action due to the Kerr effect does not occur, the beam is once condensed by the beam waist and then propagated as a divergent beam 10. When the point is formed in the beam waist, the filament-like channel 8 propagates along the channel 8 inside the object to be processed, which is formed over the distance 13, and moves toward the back surface 44 while consuming the laser beam energy. If the energy enough to maintain the Kerr effect is maintained even on the back surface 44, one of the workpieces in the channel 8 is maintained. Is compressed to the surroundings by the shock wave, and as a result, a thin cavity is formed, and the rest is discharged to the outside from the back surface, or when it is not discharged, a bulge is formed on the back surface 44, and an elongated cavity is formed along the channel 8 along the beam waist. 6 is formed over a distance 14 from the back surface 44. The beam that has reached the back surface 44 without being absorbed by the workpiece is no longer confined by the self-focusing action and is emitted as a divergent beam 11.

数式１において、λはレーザ波長、ｎ₀は物体の屈折率、ｎ₂は物体の非線形屈折率とする。
数式１によると、例えば石英ガラスの自己集束の臨界閾値パワーは２．３ＭＷであり、被加工物体に入射されたレーザパルスのピーク出力（レーザパルスエネルギーをレーザパルス幅で除算した値）がこの値よりも大きくなると自己集束作用が顕著に起こる。
According to the document JH Marburger, Prog. Quantum Electron., Vol. 4, p.35 (1975), the critical threshold for self- focusing is a condition that makes the beam focusing effect due to the self- focusing action in the workpiece to be remarkable. There is an index represented by Formula 1 called power P _cr .

In Equation 1, λ is the laser wavelength, n ₀ is the refractive index of the object, and n ₂ is the nonlinear refractive index of the object.
According to Equation 1, for example, the critical threshold power of self- focusing of quartz glass is 2.3 MW, and the peak output of the laser pulse incident on the workpiece (the value obtained by dividing the laser pulse energy by the laser pulse width) is this value. If it is larger than 1, the self- focusing action will be remarkable.

By adjusting the energy, wavelength, pulse width, focal length of the condensing lens, and condensing position of the ultrashort pulse laser, it is possible to change the occurrence of the self- focusing action. Thereby, a cavity reaching the back surface or a cavity reaching the back surface is formed. Here, the vicinity of a surface includes a distance of about 1/10 of the thickness of an object to be processed such as a substrate in the inner direction from the surface. The cavity formation state can be set as follows.
(1) Since the cavity does not reach the back surface, a raised structure with low mechanical strength is formed in which the back surface is raised higher than the surrounding surface.
(2) By forming the condensing channel to the back surface, the cavity is formed to the back surface.
(3) The condensing channel is formed from the front surface to the back surface, so that a cavity is formed from the front surface to the back surface.
(4) The condensing channel is formed only from the front surface to the inside of the processed object, so that the cavity is formed only from the front surface to the inside of the processed object.

  According to the present invention, an ultrashort pulse laser beam having a wavelength transparent to an object to be processed is condensed to a sufficiently small laser beam cross-sectional area in a substrate by a condensing optical system. A high power density condensing point is realized, so that once the laser beam propagating into the substrate is condensed, a self-focusing action due to the Kerr effect occurs, while a defocusing action due to plasma occurs at the condensing point. Due to the balance between these two actions, the propagation of the laser pulse light forms a self-trapped filament with a self-focusing action. This trapped range is the propagation of laser light by self-focusing up to a distance many times greater than the depth of focus of the beam waist formed near the focal point under conditions where self-focusing does not appear at normal power levels. A channel can be formed. The length of the channel varies with parameters such as material properties, laser beam power density, and energy. The end of the channel in the laser beam propagation direction reaches the back surface, and then the energy accumulated inside the channel creates a local high-temperature, high-pressure state, and the force from the inside to the outside acts. A cavity is formed and remains in the trace of passage of the collecting channel of action.

  As shown in FIG. 2, an ultrashort pulse laser beam 2 is formed into a scanning line 48 through a cavity formed by a long cylindrical channel formed by a self-focusing action formed long in the traveling direction 16 from the focal point of the laser beam in the workpiece 4. Form along. Furthermore, when braking is performed by applying a bending stress 49 in a direction perpendicular to the scanning line 48 after formation, a very deep hole is formed compared to the hole diameter, and therefore a line (scribe line) along the groove is formed. It acts as a starting point for braking and can be cut along the scribe line even with relatively weak stress. Since a continuous shallow groove or a structurally weak raised structure is formed on the back surface of the substrate, the braking direction is surely generated only along the scanning line 48, in other words, along the scribe line. If the surface has a hole near the back surface or the channel exit is higher than the surrounding surface, the mechanical strength may be weak. In either case, scan the laser beam in the direction you want to cut the substrate. Thus, a processed shape from the deep inside of the substrate to the back surface is formed along the scanning line 48, in other words, the scribe line. Since the depth of the processed groove is sufficiently obtained, the substrate can be cut along the scanning line 48 with a small bending stress 49 thereafter. The scribe line can be formed not only by moving the laser beam but also by moving the workpiece 4. Any movement is referred to as relative scanning. Also, when scanning the laser beam in the direction to be broken, it is possible to provide scribe lines continuously on the fracture surface by adjusting the scanning speed, or to provide scribe lines discretely at intervals. In any case, the substrate can be cut along the scribe line with a small bending stress.

FIG. 3 shows a method in which a laser beam is focused on a certain height of the workpiece, the workpiece is once scanned and machined, the laser beam condensing position is changed, and the machining is performed again. Show. First, as shown in (a), the beam waist of the laser beam is aligned with the cavity forming distance 57 (about 135 μm) away from the back surface 44 of the workpiece 4 to form the channel 8 by the self- focusing action. Then, it scans once along the scanning direction 47 linearly. Thereby, the cavity row is formed linearly. Next, as shown in (b), the condenser lens 3 is moved along the optical axis direction, and the channel 8 is formed by shifting the height at which the beam waist is formed by the cavity forming distance of about 58 to the front side. Scan again. At this time, since the scanning is performed on the processing line 35 by the first scan, the cavity row is formed so as to be connected almost continuously to the cavity row formed by the first scan. Further, if necessary, as shown in (c), scanning for beam waist height movement and cavity row formation is performed. The height movement and scanning are repeated as many times as necessary. By repeating this operation, a linear hollow wall is formed in the workpiece 4. Finally, a bending stress is applied to the workpiece 4 to cut along the cavity wall. The first scan does not necessarily require the cavity to reach the back surface. It is also possible to repeat the height movement and scanning until the beam waist reaches the front surface. By such a method, the formation of the cavity is repeated in the deep part in the object to be processed, so that it is possible to perform processing from partial cutting to full cutting.

  The substrate that is the object to be processed is not limited to one. Even a multilayer structure in which two or more substrates of the same or different materials are stacked can be processed on all substrates. In the case of a multilayer structure, the substrate may be brought into close contact with or separated from the substrate. When separated, the air gap may be air, or may be an organic material or a transparent electrode layer. In the case of using two substrates, as shown in FIG. 4, it may be composed of a lower substrate 82 placed on the opposite side of the upper substrate 81 placed on the laser incident light side, and a gap 83 may enter. With this method, the method of the present invention can be applied even to a glass composed of a plurality of layers.

In the case of two substrates as shown in FIG. 4, the lower substrate 82 is processed longer in the laser propagation direction. This is because the self- focusing action increases depending on the propagation distance in the workpiece. Further, in order to form a condensing channel by a self- focusing action, a distance laser of about 10 to 200 μm needs to propagate through the object to be processed. The longer this distance, the longer the cavity is formed with the same energy. By utilizing this, it is possible to effectively enhance the self- focusing effect and increase the cavity formation distance by placing another substrate made of the same kind or transparent material with respect to laser light on the front side of the substrate. And deeper processing. In particular, it is possible to form a condensing channel on the object to be processed from the front surface to the back surface and to form a cavity from the front surface to the back surface. Cavities may or may not be formed on other substrates that are not workpieces.

This method can be applied to cutting a glass substrate of a liquid crystal display panel. The glass substrate of the liquid crystal display panel has a structure composed of a lower substrate placed on the opposite side of the upper substrate placed on the laser incident light side with a gap interposed therebetween.
When the upper glass substrate is irradiated with an ultrashort pulse laser from the upper surface side so that the laser beam waist comes to an appropriate position on the surface of the substrate (upper glass substrate) or inside thereof, a cavity is formed in the upper glass substrate. By moving the laser light relatively, a cut surface (scribe line) is formed on the upper glass substrate.

The lower glass substrate can also be cut by irradiating an ultrashort pulse laser from the upper surface side of the upper glass substrate. Irradiation is performed so that the laser beam waist comes to an appropriate position on the surface or inside of the substrate ( lower glass substrate). The ultrashort pulse laser can transmit without damaging the upper glass substrate, and can form a cavity in the lower glass substrate. By scanning with an ultrashort pulse laser, a cut surface (scribe line) is formed on the lower glass substrate.

FIG. 5A shows a cross-sectional view of the liquid crystal display panel. The liquid crystal display panel 90 has a laminated structure including two glass substrates. Components 95 such as transparent electrodes, color filters, and thin film transistors are formed on the inner surface of the upper glass substrate 91, and components 96 such as electrodes are formed on the inner surface of the lower glass substrate 92. A liquid crystal 93 is filled between the two glass substrates. The liquid crystal is sealed in an airtight sealing material 94. In the cutting step, there is a step of separating the upper glass substrate and the second glass substrate (lower glass substrate) along the same cutting line, or a step of separating them with another cutting line slightly apart. When cutting along the same cutting line, the above-described case where two or more substrates as shown in FIG. 4 are stacked and processed on all the substrates may be applied.

FIG. 5 (a) further shows a step of cutting along another separate cutting line. In this step, the upper glass substrate is cut 97 and the lower glass substrate is cut 98. When the focused laser beam 5 is irradiated from the front surface of the upper glass substrate 91 so that the laser beam waist comes to an appropriate position inside the substrate, a cavity 61 is formed near the back surface of the upper glass substrate 91. By scanning the focused laser beam 5, a cut surface is formed on the upper glass substrate 91. At this time, the laser beam that has not been consumed for processing the upper glass substrate 91 passes through the upper glass substrate 91 and is irradiated onto the component 96 such as an electrode formed on the lower glass substrate 92. 96 may be damaged, and eventually the liquid crystal display device may be adversely affected. In order to prevent such an adverse effect, as shown in FIG. 5B, a protective coating 99 is formed in advance on the position where the laser beam of the component 96 such as an electrode is irradiated by application, adhesion or adhesion. Keep it. The protective coating 99 is opaque to the wavelength of the focused laser beam. Here, the term “opaque” includes not only the case where the laser beam is not completely transmitted, but also the case where a small amount of light is transmitted for the purpose of not damaging the component 96 such as the electrode under the protective coating 99. Shall.

Processing to the lower glass substrate 92 is performed separately from processing to the upper glass substrate 91. Similarly, the focused laser beam 5 is irradiated from the front surface of the upper glass substrate 91, but the laser beam waist is irradiated at an appropriate position inside the lower glass substrate 92. The focused laser beam 5 passes through the upper glass substrate 91 and forms a cavity 91 near the back surface of the lower glass substrate 92. By scanning the focused laser beam 5, a cut surface is formed on the lower glass substrate 92. After applying a stress to the glass substrate and separating the glass substrate, the liquid crystal display device is manufactured through an assembly process of the liquid crystal display panel with other components. Therefore, this method can be used for manufacturing a liquid crystal display panel and a liquid crystal display device.

Another embodiment in the case of multiple substrates is shown. In this embodiment, a method of dividing a structure composed of two substrates is shown. FIG. 6 is a schematic cross-sectional view for explaining this embodiment.
The structure 70 has a structure in which an upper glass substrate 91 and a lower glass substrate 92 are arranged in parallel. When used as a liquid crystal display panel, spacers are partially inserted into the structure 70 between two glass substrates. A spacer is required to provide a gap between the two glass substrates. For example, in a liquid crystal display panel, a large number of objects such as spherical silica or polystyrene or a cylindrical photoresist material are arranged. In the present embodiment example, an airtight sealing material 94 is inserted between two glass substrates. Originally, the glass substrate and the airtight sealing material 94 are intended to form a closed space. When no other object is inserted, it also serves as a spacer. When the hermetic sealing material 94 is not inserted, the spacer 94 is inserted separately. On the upper surface of the lower glass substrate 92, a metal thin film wiring 89 is provided in a range where there is. When the hermetic sealing material is provided, an electronic component (not shown) is disposed on the lower glass substrate 92 in the closed space, and the metal thin film wiring 89 is electrically connected to the electronic component. It is preferable that the airtight sealing material 94 is disposed. If the structure is a liquid crystal display panel, a display device element is formed in the closed space.

  Here, in order to make the metal thin film wiring 89 on the lower glass substrate 92 accessible from the outside, the structure 70 is separated. First, the ultrashort pulse laser beam 2 is condensed by the condenser lens 3 from the upper surface side of the upper glass substrate 91, and the laser beam waist is appropriate on the upper surface (laser light incident side surface) or inside of the lower glass plate 92. Irradiate so as to come to a position (in the figure, the laser beam waist is on the upper surface, but not limited thereto, the same applies hereinafter). However, it is set as the position where there is no metal thin film wiring 89 among lower glass plates. The laser beam 2 passes through the upper glass substrate 91 and forms a cavity 64 in the lower glass substrate 92 by a self-focusing action. By relatively moving the laser beam 2, cavities are formed continuously or discretely, and a first scribe line 88 is formed in the lower glass substrate 92.

  Next, the condenser lens 3 is moved upward, and the laser beam waist is irradiated so as to come to an appropriate position on the upper surface of the upper glass plate 91 (surface on the laser light incident side) or inside. A cavity 63 is formed in the upper glass plate 91 by a self-focusing action. By relatively moving the laser beam 50, cavities are formed continuously or discretely, and second scribe lines 87 are formed in the upper glass substrate 91. The second scribe line 87 is formed immediately above the first scribe line 88. Next, or prior to the formation of the first and second scribe lines 88 and 87, a third scribe line 86 is formed on the upper glass plate 91 in the same manner as the second scribe line 87. In this process, a cavity 62 is formed. The third scribe line 86 is preferably provided at a position close to the hermetic sealant or the spacer 94 between the upper and lower glass substrates 91 and 92, and usually straddles the metal thin film wiring 89 on the upper surface of the lower glass substrate 92. Formed. The third scribe line 86 is formed in parallel with the second scribe line 87 at a distance 77 (ΔY).

  When the electronic component is disposed inside the closed space that includes the hermetic sealant and the two substrates, the third scribe line is outside the closed space. It is preferable to provide at a position close to the hermetic sealant 94.

  At this time, since the laser beam 2 that has not been consumed by the third scribe line creation 86 in the upper glass substrate 91 passes through the upper glass substrate 91 and is irradiated onto the metal thin film wiring 89, there is a possibility of damaging them. is there. However, the intensity of the laser beam 2 transmitted through the upper glass substrate 91 is usually not strong enough to damage them. In order to prevent damage, it is also possible to form a protective coating on the position of the metal thin film wiring 89 that is irradiated with the laser beam in advance by coating, bonding or adhering. The protective coating is removed after being cut along the third scribe line to be accessible from the outside as described later. The protective coating should be opaque to the wavelength of the laser beam. Opaque is not limited to not completely transmitting the laser beam, but it may be a slight amount for the purpose of not damaging the component. It also includes transmitting light.

  After the first to third scribe lines are formed in this way, when the structure 70 is subjected to bending stress along the first scribe line 88 and the second scribe line 87 directly above the structure 70, both the lower and upper glass substrates are formed. The structure 70 is divided along the first and second scribe lines by breaking the portions where the first and second scribe lines are provided. Next, when a stress is applied to the upper glass substrate 91 along the third scribe line, the distance ΔY portion between the second and third scribe lines in the upper glass substrate 91 is separated. The structure 70 is cut by the above procedure.

  FIG. 7 shows the two-layer structure cut in this way. The lower glass substrate 92 extends by ΔY corresponding to the second and third scribe line intervals 11 and has a step structure that does not have the upper glass substrate 91 in the upper part. The portion where the lower glass substrate 92 spreads can be accessed from the outside. Therefore, it is possible to newly form electronic parts such as a control circuit and metal thin film wiring. Further, when the metal thin film wiring led out from the inside of the hermetic sealing portion is provided on the lower glass substrate, it is possible to connect the wiring of the portion led out to the outside.

  In FIG. 7, each of the cross sections 66 and 65 of the lower glass substrate 92 and the upper glass substrate 91 is a cross section divided from the first scribe line 88 and the third scribe line 86 as starting points. The side surfaces 68 and 67 of the glass plate are divided after the ultrashort laser pulse is focused from the upper part to form the scribe lines on the lower and upper glass substrates, respectively, in the same way as the first and second scribe lines 88 and 87 are formed. Can be formed.

  According to this embodiment, since the laser beam can be irradiated and processed only from one side of the glass structure, the equipment can be simplified. In addition, since the portion of the lower substrate that does not have the upper substrate can be formed, it is possible to access from the outside, and electronic components such as control circuits or metal thin film wiring can be provided from the upper surface of the lower substrate or on the substrate. It can be provided. For this reason, the display panel can be thinned. In addition, the metal thin film wiring portion led out from the inside of the hermetic sealing portion to the outside can be connected to the other.

  FIG. 8 is a diagram showing an example in which the present embodiment is applied to the manufacture of a liquid crystal panel. This embodiment is implemented in the process of dividing the large structure 70 having the upper and lower large glass substrates 91 and 92 on which a large number of liquid crystal panels are formed into individual panels 80 after the liquid crystal panel is manufactured. In a space surrounded by the glass substrates 91 and 92 and an airtight sealant 94 inserted between them, a color filter, a liquid crystal 93, a driving transistor, a wiring, a spacer and the like necessary for the liquid crystal display panel (other than the liquid crystal are illustrated). Not built-in). (A) is a top view and a cross-sectional view, and (b) is an enlarged cross-sectional view cut along the Y direction. The Z direction is a direction perpendicular to the paper surface.

  The scribe lines 74-1 to 74-m along the X direction are formed as follows. The first scribe line 88 is formed on the lower glass substrate 92 in a portion where the metal thin film wiring 89 is not provided on the lower glass plate on the upper surface. Further, the second scribe line 87 is formed on the first scribe line 88 in the upper glass substrate 91. Further, a third scribe line is preferably provided on the upper glass substrate at a position close to the hermetic sealant 94. The third scribe line 86 is parallel to the second scribe line 87 by a distance 77 (ΔY). The third scribe line 86 is usually formed so as to straddle the metal thin film wiring 89.

  The scribe lines 73-1 to 73-n along the Y direction are simply provided one by one at an interval of the panel width 76 one by one. The first and second scribe lines are provided in the same manner as the method.

  After the scribe line is formed, the liquid crystal display panel 80 is divided along the scribe lines formed on the upper and lower glass substrates, and thus can be divided in the X and Y directions. Can be manufactured. In that case, in particular, a metal thin film wiring 89 is taken out from the inside of the hermetic sealant 94 to the outside on the lower glass substrate 92 on at least one side surface of the liquid crystal display panel 80 and can be easily accessed from the outside. Therefore, a structure capable of various electrical connections can be realized.

  When a plurality of display panels are individually divided from a large two-layer structure having a large number of sheets according to the present embodiment, a scribe line is processed and provided on two glass substrates by irradiating a laser beam only from one side. Since it is possible, the reverse conveyance means of a large glass is unnecessary. Furthermore, ΔY is formed on two upper and lower glass plates that can be easily accessed from the outside on one substrate without damaging a metal film such as an electric wiring from the internal structure of the display panel to the outside with a laser beam. A step structure can be formed with a width of. Since the edge of the upper glass substrate is removed as a portion between the second and third scribe lines on the metal thin film or electronic component provided on the surface facing the upper glass plate near the scribe line on the surface of the lower glass substrate, Easy access from outside. Moreover, the metal thin film wiring led out from the inside of the display panel beyond the sealing portion on the lower glass substrate becomes possible. Therefore, wiring can be performed from the outside of the sealing portion.

  This method can be applied to cutting not only a liquid crystal display panel but also other flat panel display panels such as a plasma display panel. Moreover, this method can be used for the manufacturing process of these flat panel display panels.

  Although the substrate constituting the structure is made of glass, the material targeted by the invention is not limited to this. Further, although the substrate has two layers, it is obvious that the present invention can be applied to a case having three or more layers.

  FIG. 9 shows an embodiment of a bevel (inclined surface) machining method. The ultrashort pulse laser beam 2 from the ultrashort pulse laser generator 1 is rotated 52 while being deflected by a fixed angle θ around the rotation axis 55 using a rotating mirror 51. When the condensing lens 3 that rotates integrally with the rotating mirror 51 while the optical paths of the rotating laser beams 53 and 54 coincide with the optical axis is used, the focal point of the condensing lens 3 draws a circular locus. A substrate-like object to be processed 4 is arranged on a processing object mounting means (not shown) such as a stage. If the substrate-like workpiece 4 is arranged so that the normal to the front surface is parallel to the rotation axis 55 by keeping the circular locus parallel to the mounting surface of the processing object mounting means, the laser beam irradiation position is set. It is possible to rotate and scan the workpiece 4 to irradiate a circular locus. In this case, the workpiece 4 is tilted at an angle θ from the rotation shaft 55. First, the beam waist is aligned with the cavity forming distance 57 (about 135 μm) away from the back surface 56 of the workpiece 4 and scanned on the filament in a direction shifted by an angle θ from the normal line. A hollow row is formed in a circular shape. Further, by moving the condenser lens 3 in the direction of the rotating mirror 51 along the optical axis direction, the cavity formation distances 58 and 59 are sequentially moved to form a cavity row for each movement, and scanning is repeated. A circular hollow wall extending from the front side to the back side of the object 4 is formed. Then, by bending and separating, the periphery is processed into an inclined surface and cut into a circle. As described above, the present invention can be performed not only in the vicinity of the surface of the object to be processed but also in the interior by repeating the formation of the cavity, and can perform processing from partial cutting to full cutting.

  In the above laser processing, the pulse energy is preferably 1 mJ or less, and more preferably 10 μJ or less. In the case of 10 μJ or less, a clean and smooth cut surface can be obtained, cracks are few and the fracture strength is high. If a crack exists, the strength of an object to be processed such as glass becomes weak, which may be inconvenient. When the pulse energy is large, when trying to process the vicinity of the front surface, the center or rear end of the pulse is reflected, scattered, or absorbed by the free electron plasma created by the front end of the pulse near the front surface. In some cases, it is difficult to form a cavity. When the pulse energy is small, the density of free electron plasma generated in the vicinity of the front surface is reduced, and the propagation of the pulse is not greatly inhibited, so that a hollow channel can be easily formed inside the glass.

The ultrashort pulse laser is a laser having a pulse width of 100 ps or less, and the pulse width is preferably 500 fs to 10 ps, and most preferably about 2 ps. This is because the stress required when cleaving the glass substrate after continuously forming the fracture surface is reduced, and the quality of the fractured surface is good.
Further, when a glass substrate is used as an object to be processed, a pulse width of 150 femtoseconds and an output energy of 1 μJ or more are suitable.

  As described above, the present invention uses a beam waist having a small focal depth of a focused beam of ultrashort pulses, and uses a self-focusing action formed inside the object to be processed. A new processing method can be provided that can be used to increase the number of steps. This method is a precision machining method that can be realized only by the interaction between the laser beam and the workpiece, which is not found in the conventional machining method.

  The laser medium was a titanium sapphire crystal (center wavelength 780 nm), a pulse width of 150 femtoseconds, and an output energy of 1 μJ or more. Further, the object to be processed was Corning Eagle 2000, which is a glass substrate, and the thickness was 700 μm. When there is no description different from this in each Example, these are common in all Examples.

In this embodiment, the structure shown in FIG. 1 is used to observe changes that occur in the object to be processed when the condensing position when the object is irradiated with laser is moved from the front surface to the inside, and the principle of the present processing method is observed. This is an experimental example to demonstrate the above.
FIGS. 10 and 11 show micrographs of cross-sectional views in which changes occurring in the workpiece are observed. FIG. 10 shows the front surface 45 of the substrate that is the object to be processed, and FIG. 11 shows the vicinity of the back surface 44. For the configuration shown in FIG. 1, an aspherical lens with an aberration correction in which the incident beam diameter of the lens is 6 mm and the focal length f of the condenser lens 3 is about 3.1 mm is used. When the transverse mode of the laser beam is a Gaussian beam, the beam diameter at the focal point is about 1 μm, and the depth of focus in the range including 90% of the energy at the beam waist is calculated to be 1 μm or less. When the workpiece 4 is irradiated with an ultrashort pulse laser beam having a small value of the focal depth as described above, when the beam is focused and irradiated so that the position of the beam waist is placed on the front surface 45, FIG. Then, the shallow portion 21 indicated by the depth 23 is removed from the front surface 45, and when the beam waist is further moved to the inside, the surface removal amount is reduced. When the position of the beam waist is further moved to the inside, the workpiece 4 is moved. The areas 24, 25, etc. in which optical distortion occurs are generated in the peripheral portion according to the position in the depth direction where the beam waist is placed. When the beam waist was placed inside, the surface removal processing decreased, and instead the internal optical distortion appeared and the areas 24 and 25 appeared.

  FIG. 11 is a cross-sectional observation photograph when the beam waist is further moved inside the substrate. It was observed that portions 31 and 32 in which an optical change occurred in the beam waist portion were generated on the front surface 45 with no change. Furthermore, a portion 33 was observed in which an optical change occurred within a range of several hundreds of μm from the inside to the back surface as it approached the back surface 44 of the workpiece. Further, when the beam waist was close to about 135 μm from the back surface 44, a cavity 34 was linearly formed from the inside to the back surface in the form of a filament. Further, when the laser beam waist was matched with the back surface 44, only the vicinity of the back surface was removed. From such a processing result, even though the focal depth 37 of the laser beam is about 1 μm as described above, the filament-shaped cavity 34 having the diameter of the beam waist has a cavity formation distance ( When the self-focusing effect is not exhibited, the filament-like cavity processing is performed over a range that is about two orders of magnitude longer than the processing only in the range of the focal depth of the beam (about 1 μm). Was done.

In this example, laser light is scanned while forming a cavity channel near the back surface, and a cut surface is formed by the cavity channel.
When a filament-like cavity is formed by the self-focusing action, a funnel-shaped portion 43 may be formed together with the back surface as shown in FIG. The funnel-shaped portions 43 are overlapped with each other, and the filament-like cavities are individually formed at the same location as the channel 8, and the ultrashort laser pulses are relative to each other along the back surface 44 of the workpiece. Thus, a large number of filamentous cavities arranged in an envelope 46 having a predetermined processing depth along the scanning direction were formed. FIG. 12 also shows a micrograph of the cut surface of the filamentous cavity formed in this way. In this example, after scanning with a laser pulse at a scanning speed of 3 mm / s, the cross section was observed by folding along a scanning line and dividing. In this figure, in processing of the thickness 41 of the object to be processed, a large number of filament-like hollow channels are formed across the envelope 46 in the range from the back surface 44 to the depth 42, and the object is divided from that as the starting point. A processed cross section of the processed object is shown. FIG. 13 is a scanning micrograph showing a cross section of the cavity 61, and FIG. 14 is a scanning micrograph in which the vicinity of the back surface is particularly enlarged. A raised structure 71 having a weak mechanical strength is shown in which the surface of the portion where the cavity 61 is formed is raised from the surroundings.

  In the configuration as shown in FIG. 3, the beam waist height was changed, scanning was performed a plurality of times, and processing was performed near the back surface. FIG. 15 shows a cross section when the number of scans is 4, the pulse energy is 10 μJ, and the pulse width is 2 ps. By reducing the pulse energy and optimizing the pulse width, a high-quality processed region 36 was formed near the back surface.

  Also in this example, processing was performed by scanning a plurality of times while changing the height of the beam waist in the configuration as shown in FIG. In this example, the beam waist was formed so as to set the processing region near the front surface of the glass substrate. FIG. 16 shows a cross section when the number of scans is 10 and the pulse energy is 1 μJ and the pulse width is 2 ps. By optimizing the pulse energy and the pulse width, a good machining region 36 extending to the front surface was obtained.

  In this embodiment, the object to be processed has a laminated structure of two glass substrates. With the configuration shown in FIG. 4, the laser condensing position was changed from the front surface to the back surface of the upper substrate 81 made of glass. FIG. 17 shows a micrograph after processing of two glass substrates. The processing is performed not only on the upper glass 81 but also on the lower glass 82 placed on the back side thereof. The upper glass 81 was processed over a maximum of 150 μm, and the lower glass 82 was processed over a maximum of 250 μm. As described above, the substrate placed underneath was processed longer in the laser propagation direction.

The embodiments of the present invention have been described above. Obviously, modifications may be made to the invention without departing from the scope of the invention as set forth in the appended claims.
Moreover, this application contains the aspect described below.
(Aspect 1)
The ultrashort pulse laser beam having a wavelength that is transparent to the workpiece having the first surface and the second surface is condensed through the condensing means, and the condensed light is collected from the first surface side. The laser beam is irradiated so that the beam waist position of the laser beam is formed between the first surface and the second surface of the workpiece, and the ultrashort pulse high peak laser beam propagation inside the workpiece is performed. The condensing channel is formed in the traveling direction of the laser beam by the self-focusing action of the laser beam, so that a cavity reaching the second surface or near the second surface is formed in the condensing channel portion. A laser processing method characterized by the above.
(Aspect 2) The laser processing method according to aspect 1, wherein the pulse laser beam has a pulse width of 100 ps or less.
(Aspect 3) The laser processing method according to aspect 2, wherein the pulse laser beam has a pulse width of 500 fs to 10 ps.
(Aspect 4) Any one of Aspects 1 to 3, wherein a raised structure having a low mechanical strength is formed in which the vicinity of the intersection with the second surface in the laser beam traveling direction is raised higher than the peripheral surface. The laser processing method according to one item.
(Aspect 5) The laser processing according to any one of Aspects 1 to 3, wherein the condensing channel is formed up to the second surface, whereby the cavity is formed up to the second surface. Method.
(Aspect 6) Aspects 1 to 3 wherein the condensing channel is formed from the first surface to the second surface, whereby the cavity is formed from the first surface to the second surface. The laser processing method as described in any one of these.
(Aspect 7) Aspects 1 to 3, wherein the condensing channel is formed from the first surface to the inside of the processed object, whereby the cavity is formed from the first surface to the inside of the processed object. The laser processing method as described in any one of these.
(Aspect 8) The laser according to any one of Aspects 1 to 7, wherein the workpiece is a dielectric material such as glass, sapphire, or diamond, or a semiconductor material such as silicon or gallium nitride. Processing method.
(Aspect 9) The laser processing method according to any one of Aspects 1 to 8, wherein the ultrashort pulse laser beam is an output pulse having a pulse energy of 1 mJ or less.
(Aspect 10) The laser processing method according to any one of aspects 1 to 8, wherein the ultrashort pulse laser beam is an output pulse having a pulse energy of 10 μJ or less.
(Aspect 11) The laser processing method according to any one of Aspects 1 to 10, wherein the object to be processed is a flat object.
(Aspect 12) The laser processing method according to any one of aspects 1 to 11, wherein the object to be processed is a silicon substrate, and the wavelength is 1 μm to 2 μm.
(Aspect 13) The laser processing method according to any one of Aspects 1 to 12, wherein the object to be processed has a multilayer structure in which two or more flat objects of the same or different materials are stacked.
(Aspect 14) The laser processing method according to Aspect 13, wherein an object to be processed having the multilayer structure is in close contact or an air gap, an organic material, or a transparent electrode layer exists between them.
(Aspect 15) The length of the condensing channel due to the self-focusing action generated in the object to be processed by installing another object transparent to the laser wavelength on the first surface side of the object to be processed The laser processing method according to any one of aspects 1 to 14, wherein: is changed.
(Aspect 16) The condensing channel by the self-focusing action generated in the object to be processed is provided by placing another object transparent to the laser wavelength on the first surface side of the object to be processed. The laser processing method according to any one of aspects 1 to 15, wherein the laser processing method reaches the surface.
(Aspect 17) The ultrashort pulse laser beam condensed inside the object to be processed by the condensing unit is relatively moved at an arbitrary speed along the cutting direction, thereby spatially overlapping the cavities. The laser processing method according to any one of aspects 1 to 16, wherein the laser processing method is provided.
(Aspect 18) The ultrashort pulse laser beam condensed inside the object to be processed by the condensing means is relatively moved at an arbitrary speed along a cutting direction, thereby spatially separating the cavities. The laser processing method according to any one of aspects 1 to 17, wherein the laser processing method is provided.
(Aspect 19) The object to be processed is a planar object, and the focused laser beam of the ultrashort pulse laser is incident at an angle from the normal direction of the first surface of the object to be processed. The processing method using a laser according to the aspect 17 or 18, wherein the focused laser beam is rotated while giving the inclination of the angle, circular scanning is performed, and the processing surface is inclined and processed.
(Aspect 20) The laser processing method according to any one of Aspects 17 to 19, further comprising an operation of performing the relative movement a plurality of times and changing a height of a beam waist of the laser light between the relative movements.
(Aspect 21) The object to be processed is cut with a small amount of stress along the processed part after performing laser processing on the object to be processed by the method according to any one of aspects 17 to 20. Cutting method of processed object.
(Aspect 22) The method for cutting a workpiece according to Aspect 21, wherein the workpiece is a substrate of a liquid crystal display panel.
(Aspect 23) The method for cutting an object to be processed according to aspect 22, wherein the liquid crystal display panel has a laminated structure of a first substrate and a second substrate, and the first substrate side of the second substrate A laser is applied so that a beam waist is formed in the first substrate from the side of the first substrate by applying or adhering or adhering a material opaque to the laser wavelength on the component mounted on the surface of the first substrate. A method for cutting a liquid crystal display panel substrate, comprising the step of irradiating, wherein the laser beam that has passed through the first substrate does not damage the component during the irradiation.
(Aspect 24) A method for producing a liquid crystal display panel, comprising the liquid crystal display panel substrate cutting method according to Aspect 22 or 23.
(Aspect 25)
An ultrashort pulse laser having a pulse width of 100 ps or less, having a wavelength transparent to the first and second substrates, in the first and second substrates and a structure disposed in parallel with a spacer partially interposed therebetween. Is condensed through the condensing means, and irradiated from the outside of the first substrate so that the beam waist position is formed on the surface or inside of either one of the substrates. By forming a condensing channel in the traveling direction of the short pulse laser beam, a cavity is formed in the condensing channel portion, and a scribe line is formed by relatively moving the ultrashort pulse laser beam. And a substrate cutting step of cutting the substrate on which the scribe line is formed along the scribe line, and the scribe line formation includes the following A: Dividing method of the structure step has a following C.
A: The ultrashort pulse laser is focused so as to pass through the first substrate, and the beam waist comes to the second substrate to form the first scribe line on the second substrate, and the beam waist is further formed on the first substrate. Forming a second scribe line on the first substrate by focusing the light so as to be located at the same position and relatively moving the ultrashort pulse laser at the same plane position as the first scribe line.
C: dividing the structure by cutting the second and first substrates along the first and second scribe lines.
(Aspect 26)
The scribe line forming step further includes the following B, and is performed in the order of the A, the B or the B, the A, and the substrate cutting step further includes the following D, the C, the order of the D 26. A method according to embodiment 25 to be performed.
B: Condensing the ultrashort pulse laser so that the beam waist is positioned on the first substrate, and relatively moving the ultrashort pulse laser light in parallel with the second scribe line at a predetermined distance. And forming a third scribe line on the first substrate.
D: A step of removing the portion of the third scribe line from the second scribe line of the first substrate by cutting the first substrate along the third scribe line.
(Aspect 27)
27. The method according to aspect 26, wherein the structure has a metal thin film on a surface of the first substrate facing the second substrate side.
(Aspect 28)
The method according to aspect 27, wherein a third scribe line formed on the second substrate traverses the metal thin film in space.
(Aspect 29)
27. The method according to aspect 25 or 26, wherein the spacer includes a sealing material that forms a space surrounded by the first and second substrates and the sealing material.
(Aspect 30)
The spacer includes a sealing material that forms a space surrounded by the first and second substrates and the sealing material, an electronic component is formed in the space, and the metal thin film is 29. The method according to aspect 27 or 28, wherein the method is provided across an inner side and an outer side of a space, and the metal thin film is electrically connected to the electronic component.
(Aspect 31)
The method according to any one of aspects 25 to 30, wherein the first substrate and the second substrate are both glass substrates.
(Aspect 32)
32. The method according to any one of aspects 25 to 31, wherein the structure is a liquid crystal display panel or a plasma display panel.
(Aspect 33)
A method for manufacturing a liquid crystal display panel or a plasma display panel, comprising the method according to aspect 32.
(Aspect 34) Ultrashort pulse laser generator;
A rotating mirror that rotates by deflecting the pulse laser beam generated from the ultrashort pulse laser generator at a constant angle;
A condensing lens that rotates in synchronism with the rotating mirror so that the optical path and optical axis of the deflected pulsed laser light coincide with each other, and the focal point draws a circular locus by the rotation;
Means for moving the condenser lens along the optical axis direction;
Processed object mounting means
A laser processing apparatus.

It is a block diagram explaining the processing method of the to-be-processed object using the self-focusing effect | action by the Kerr effect regarding this invention. It is a block diagram which scans a laser and performs substrate processing. It is a figure which shows the method of changing a condensing position of a laser beam condensing point, and processing again after scanning and processing a to-be-processed object. It is a block diagram which processes into the multilayer structure which consists of two board | substrates. It is explanatory drawing in the case of cut | disconnecting a liquid crystal panel structure and two glass substrates in another position. It is typical sectional drawing for demonstrating the division | segmentation method of the structure which consists of two board | substrates. An example of the general shape of a glass structure composed of two substrates is shown. It is explanatory drawing in the case of dividing | segmenting into a separate liquid crystal display panel from a large sized glass structure. It is a figure which shows embodiment which applied the processing method of this invention to the inclined surface process. It is a figure which shows the result of a 1st Example, and is a microscope picture of the to-be-processed object front surface surface vicinity. It is a figure which shows the result of a 1st Example, and is a microscope picture of the to-be-processed object back surface vicinity. It is a figure which shows the result of 2nd Example, and is explanatory drawing and the microscope picture of the cut surface by a cavity channel. It is a figure which shows the result of a 2nd Example, and is a scanning microscope picture which image | photographed the cross section of the cavity 61. FIG. FIG. 13 is a scanning micrograph in which the vicinity of the substrate back surface is particularly enlarged. It is a figure which shows the result of a 3rd Example, and is a microscope picture of a cut surface. It is a figure which shows the result of a 4th Example, and is a microscope picture of a cut surface. It is a figure which shows the result of a 5th Example, and is a microscope picture which shows after the process of two board | substrates.

As an application example of the present invention, in processing of a workpiece to be used for a display device such as a semiconductor device or a liquid crystal, the substrate of a silicon wafer, a thin film transistor or a display device, high-voltage power semiconductor substrate processing, and other multi-layered electronic elements This is effective for fine processing with little thermal influence when the removal processing inside the layer proceeds from the surface. In the manufacture of highly integrated circuits, it is possible to reduce the manufacturing cost of electronic components by improving the product yield by reducing the processing width and reducing the amount of processed removal. Furthermore, the effectiveness can be obtained for drilling a substrate of a semiconductor device such as quartz or sapphire. It is also effective for processing a filter in which many fine holes are provided. Furthermore, the present invention can be used for manufacturing an electronic device using a multilayer glass structure such as a liquid crystal display panel and a plasma display panel.

Claims (19)

The ultrashort pulse laser beam having a wavelength that is transparent to the workpiece having the first surface and the second surface is condensed through the condensing means, and the condensed light is collected from the first surface side. The laser beam is irradiated so that the beam waist position of the laser beam is formed between the first surface and the second surface of the workpiece, and the ultrashort pulse high peak laser beam propagation inside the workpiece is performed. By forming a condensing channel in the traveling direction of the laser light by the self-focusing action by, a laser processing region including a cavity in the condensing channel is formed,
The condensing channel is formed from the inside of the workpiece to the second surface, whereby the cavity is formed from the inside of the workpiece to the second surface, or the condensing channel is formed from the first surface. by being formed to a second surface, said cavity or formed from the first surface to the second surface, by the condenser channel is formed from the first surface to the inside the processed object, the cavity is formed from the first surface to the inside the processed object,
Changing the length of the condensing channel due to the self-focusing action generated in the workpiece by installing another object transparent to the laser wavelength on the first surface side of the workpiece. A laser processing method characterized by the above. The laser processing method according to claim 1, wherein the pulse laser beam has a pulse width of 100 ps or less. The laser processing method according to claim 2, wherein the pulse laser beam has a pulse width of 500 fs to 10 ps. 4. The laser processing according to claim 1, wherein a raised structure is formed in which the vicinity of the intersection with the second surface in the laser beam traveling direction is raised higher than the peripheral surface. 5. Method. The laser processing method according to any one of claims 1 to 4, wherein the object to be processed is a dielectric material such as glass, sapphire, or diamond, or a semiconductor material such as silicon or gallium nitride. 6. The laser processing method according to claim 1, wherein the ultrashort pulse laser beam is an output pulse having a pulse energy of 1 mJ or less. The laser processing method according to claim 1, wherein the ultrashort pulse laser beam is an output pulse having a pulse energy of 10 μJ or less. The laser processing method according to claim 1, wherein the object to be processed is a flat object. 9. The laser processing method according to claim 1, wherein the object to be processed is a silicon substrate, and the wavelength is 1 μm to 2 μm. 10. The laser processing method according to claim 1, wherein the object to be processed has a multilayer structure in which two or more flat objects of the same kind or different materials overlap each other. 11. The laser processing method according to claim 10, wherein an object to be processed having the multilayer structure is in close contact, or an air gap, an organic material, or a transparent electrode layer exists between them. A spatial overlap of the cavities is provided by relatively moving the ultrashort pulse laser beam condensed inside the object to be processed by the condensing means at an arbitrary speed along a cutting direction. The laser processing method according to any one of claims 1 to 11. The ultrashort pulse laser beam condensed inside the object to be processed by the condensing means is relatively moved at an arbitrary speed along a cutting direction, so that the cavities are spatially separated. The laser processing method according to any one of claims 1 to 12. The object to be processed is a planar object, and the focused laser beam of the ultrashort pulse laser is incident at an angle with respect to the normal direction of the first surface of the object to be processed, and The laser processing method according to claim 12 or 13, wherein a circular scanning is performed by rotating the optical laser light with the inclination of the angle, and the processing surface is inclined. The laser processing method according to claim 12, further comprising an operation of performing the relative movement a plurality of times and changing a height of a beam waist of the laser light during each relative movement. 16. A method for cutting an object to be processed, comprising: cutting the object to be processed along a processed part after performing laser processing on the object to be processed by the method according to any one of claims 12 to 15. 17. The method for cutting an object to be processed according to claim 16, wherein the object to be processed is a substrate of a liquid crystal display panel. 18. The method for cutting an object to be processed according to claim 17, wherein the liquid crystal display panel has a laminated structure of a first substrate and a second substrate, and the surface of the second substrate on the first substrate side. A step of irradiating a laser so that a beam waist is formed in the first substrate from the side of the first substrate by applying, bonding or adhering a material opaque to the laser wavelength on the component mounted on the substrate A method for cutting a liquid crystal display panel substrate, wherein the laser beam that has passed through the first substrate is not damaged during the irradiation. A method for manufacturing a liquid crystal display panel, comprising the method for cutting a liquid crystal display panel substrate according to claim 17.

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