JP2008112954A - Laser processing apparatus, laser processing method, manufacturing method of wiring substrate, manufacturing method of display apparatus and wiring substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simplified and reliable laser processing method in which both improvement of a manufacture yield and reduction of manufacture throughput are obtained. <P>SOLUTION: The laser processing method includes: the steps of selecting a wavelength of laser light based on a reflectance of a multilayer film formed of two or more layers with different materials of a processing object 3; and irradiating the processing object 3 with the laser light to perform laser processing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus, a laser processing method that can be performed using the processing apparatus, a manufacturing method of a wiring board by the laser processing method, a manufacturing method of a display device including the wiring board, and the laser And a wiring board obtained by the processing method.

In a structure that is premised on mass production, a predetermined structure pattern is defined according to the purpose. As such a structure, a wiring board including a member (wiring or the like) or an element (capacitor or the like), a photomask, or the like can be given. In addition, examples of a structure including a wiring board and using a photomask in a manufacturing process include a display device such as a so-called flat panel display (FPD; flat display device).
However, in these structures, a predetermined pattern is not always completely formed in the manufacture, and members and elements are formed excessively (for example, protruding from a predetermined region) or insufficiently (for example, In some cases (non-uniformly within a given area).

As a specific example, the case of a display device will be described.
A display device (for example, a flat panel display) has a screen composed of a large number of pixels provided in a two-dimensional matrix, and has excellent characteristics such as thinness, light weight, and low power consumption. Such display devices are classified according to the driving method, but an active matrix display device in which a switch element is electrically connected to each pixel electrode suppresses crosstalk between adjacent pixels. Particularly good image quality (image) can be obtained. For this reason, active matrix display devices have been actively researched and developed, and are widely used as display devices for personal computers (PCs), televisions (TVs), and the like. The flat panel display is classified into a liquid crystal display, an organic EL display, and the like depending on the light emission method.

An active matrix display device includes a lower metal wiring pattern (for example, a plurality of scanning lines), an insulating film, and an upper metal wiring pattern (for example, a plurality of signal lines) on a transparent insulating substrate such as glass. However, a wiring board (a so-called matrix array board or array board) having a stacked configuration is provided.
The lower-layer metal wiring pattern and the upper-layer metal wiring pattern are arranged in a lattice shape extending in a direction orthogonal to each other, and a position corresponding to each grid (intersection point) of the lattice is a pixel. The upper metal wiring pattern is connected to a pixel electrode made of a transparent conductive material such as ITO (Indium-Tin-Oxide). Each pixel is provided with a switching element for controlling the electrode. When this switching element is a thin film transistor (TFT), the gate electrode of the TFT is electrically connected to the scanning line, the drain electrode is electrically connected to the signal line, and the source electrode is electrically connected to the pixel electrode. Is done.

In such a wiring board, local defects such as defects in the insulating film and disconnection of the metal wiring may occur. As a specific example of the local failure, the upper and lower wirings are electrically connected to each other at the position where the upper wiring pattern and the lower wiring pattern intersect or overlap each other due to the defect of the insulating film or the mixing of non-insulating foreign matter. And interlayer shorts.
When such a local defect occurs in a wiring board, for example, in a display device, a so-called dark spot in which some pixels do not emit light, or a so-called dark spot in which a plurality of pixels in a linear form are darkened occurs. The image display performance is significantly impaired. Therefore, in order to suppress the occurrence of local defects, management of the manufacturing process (reduction of foreign matters, suppression of defects, etc.) is attempted, but it is difficult to completely avoid the occurrence.

In order to solve this problem, a method for correcting an interlayer short circuit at a location where an upper wiring pattern and a lower wiring pattern intersect or overlap each other is disclosed (for example, Patent Document 1). This technique is a technique for correcting an interlayer short circuit at a location where an upper wiring pattern and a lower wiring pattern intersect or overlap each other. However, since laser cutting of only the upper layer is impossible on the interlayer short-circuited portion, the interlayer short-circuit is corrected by the laser cutting and bypass line wiring processes in areas other than the intersections, which complicates the process. ing.
In addition, a technique for correcting a short circuit between upper wiring patterns is disclosed (see, for example, Patent Document 2). This technique is a technique for correcting a short circuit between upper wiring patterns. However, if the necessary area for laser cutting is also present in the lower wiring section, it is not always possible to prevent an interlayer short circuit between the upper layer and the lower layer due to the action of performing laser cutting including the lower layer. It is necessary to eliminate the influence of the interlayer short, and the process is complicated.

As described above, the conventional correction method has another problem that the process is complicated, and therefore, it is inevitable that the manufacturing throughput is prolonged.
Further, in such a conventional correction method, the thickness of the multilayer film on the wiring board has been determined with a focus on miniaturization and thinning for the purpose of downsizing the apparatus. On the other hand, the present inventors have found that the laser processing can be optimized only within a range in which the correction is restricted by the film thickness as long as such a predetermined film thickness is assumed. That is, the present inventors have found that in order to perform optimum laser processing, it is necessary to select the wavelength of the laser light and the like without being restricted by a predetermined film thickness.
Japanese Patent Laid-Open No. 2001-77198 Japanese Patent Laid-Open No. 11-282010

  The present invention has been made in view of such problems, and its purpose is to provide a simpler and more reliable laser processing method capable of achieving both improvement in production yield and reduction in production throughput, An object of the present invention is to provide a method of manufacturing a wiring board by this processing method, a method of manufacturing a display device including the wiring substrate, and a laser processing apparatus.

  A laser processing apparatus according to the present invention includes at least a support base that supports a workpiece, a local exhaust apparatus that introduces laser light toward a local exhaust unit that is locally pressure-adjusted on the support base, A laser processing device having a laser light source unit for outputting the laser light, wherein the local exhaust device is capable of relatively levitating from the support table by jetting of a levitation gas to the support table; The processing object has at least a multilayer film composed of two or more layers made of different materials, and an input unit to which the reflectance of the processing object is input is connected to the laser light source unit. It is characterized by.

  The laser processing method according to the present invention is a laser processing method for irradiating a processing target with laser light, and is composed of two or more layers in which the wavelength of the laser light is different from each other in the processing target. The selection is based on the reflectance of the multilayer film.

  A method of manufacturing a wiring board according to the present invention is a method of manufacturing a wiring board by laser processing, and in the manufacturing of the wiring board, a multilayer composed of two or more layers constituting the wiring board and having different materials from each other. The laser light is irradiated onto the film, and the wavelength of the laser light is selected based on the reflectance of the multilayer film.

  A method for manufacturing a display device according to the present invention is a method for manufacturing a display device including a wiring board, and the manufacturing of the wiring board is composed of two or more layers constituting the wiring board and having different materials. This is performed by selecting the wavelength of the laser beam applied to the multilayer film based on the reflectance of the multilayer film.

  The wiring board according to the present invention is manufactured by irradiating a multilayer film composed of two or more layers made of different materials by selecting the wavelength of the laser beam based on the reflectance of the multilayer film. It is characterized by that.

  According to the laser processing apparatus of the present invention, at least a support table that supports a workpiece, and a local exhaust system that introduces laser light toward a local exhaust unit in which pressure is locally adjusted on the support table. And a laser light source unit that outputs the laser light, wherein the local exhaust device can be floated relatively from the support table by jetting of a levitation gas to the support table. The processing object has at least a multilayer film composed of two or more layers made of different materials, and the laser light source unit has an input unit to which the reflectance of the processing object is input Since they are connected, it is possible to achieve simpler and more reliable laser processing that can achieve both improvement in manufacturing yield and reduction in manufacturing throughput.

  According to the laser processing method of the present invention, the wavelength of the laser light is selected based on the reflectance of the multilayer film composed of two or more layers having different materials in the processing object. It is possible to perform simpler and more reliable laser processing capable of achieving both improvement in yield and reduction in manufacturing throughput.

  According to the method for manufacturing a wiring board according to the present invention, the irradiation of the laser beam to the multilayer film composed of two or more layers that are different from each other, constituting the wiring board, is performed based on the reflectance of the multilayer film. Since the wavelength of the laser beam is selected, it is possible to perform simpler and more reliable laser processing that can achieve both improvement in manufacturing yield and reduction in manufacturing throughput.

  According to the display device manufacturing method of the present invention, the wiring board is manufactured based on the reflectance of a multilayer film composed of two or more layers that are different from each other in the wiring board. Since it is performed by selecting the wavelength of the laser beam to irradiate the film, it is possible to perform simpler and more reliable laser processing that can achieve both improvement in manufacturing yield and reduction in manufacturing throughput. .

  According to the wiring board of the present invention, the laser beam is irradiated to the multilayer film composed of two or more layers made of different materials by selecting the wavelength of the laser beam based on the reflectance of the multilayer film. Therefore, the short circuit is surely removed and the characteristics are improved.

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

  <Embodiment of laser processing apparatus>

Embodiments of a laser processing apparatus according to the present invention will be described below with reference to the drawings.
In the present embodiment, an embodiment of a laser processing apparatus will be described using a wiring board manufacturing apparatus whose processing target is a wiring board (for example, a TFT substrate) as an example.

1A and 1B are schematic configuration diagrams of a laser processing apparatus according to the present embodiment. The laser processing apparatus 1 according to the present embodiment has at least a laser etching function, and particularly in the present embodiment, is an apparatus that also has a film forming function by a laser CVD method.
As shown in FIG. 1A, the laser processing apparatus 1 according to the present embodiment is a placement portion for the workpiece 3, that is, the support base 2 that supports the workpiece 3 when the workpiece 3 is placed, and the support base. 2, a local exhaust device for performing local film formation, which is disposed opposite to the workpiece 3 supported on 2 (in this embodiment, a local film formation etching head having both a film formation function and an etching function; Local processing head) 4. In the present embodiment, the workpiece 3 is a wiring board, and has at least a multilayer film composed of two or more layers made of different materials.

A local space (local exhaust unit 6 to be described later) in which the pulse laser beam L from a laser light source unit (not shown) is focused and introduced and the local pressure is adjusted is directly below the center of the local exhaust unit 4. It becomes. The laser light source unit is connected to an input unit to which the reflectance of the multilayer film of the workpiece 3 is input.
In addition to the raw material supply means 5, the local exhaust unit 6 is also connected with a purge gas supply means 7 for supplying a purge gas that constitutes an atmosphere together with the raw material gas. The raw material supply means 5 and the purge gas supply means 7 are connected to this local space via a raw material gas flow path 17 and a purge gas flow path 18 in the local exhaust device 4, respectively.
In addition, the contamination of the transparent window 19 can be suppressed by providing the opening of the purge gas flow path 18 facing the local exhaust part 6 at an angle slightly toward the transparent window 19. Further, when a local exhaust means (not shown) is provided in connection with the local exhaust section 6, an upward air flow is generated in the local exhaust section 6 by adjusting the exhaust balance with the exhaust means 10 and 11. It is possible to suppress the material that has been generated, removed by etching, and vaporized from being reattached to the workpiece 3.

The local exhaust device 4 further includes, for example, a compressed gas supply means 9 that floats the local exhaust device 4 by static pressure by injecting compressed argon gas (Ar) or nitrogen gas (N ₂ ) toward the support base 2. Are connected. The compressed gas from the compressed gas supply means 9 is supported by the ring-shaped compressed gas supply path 14 constituting the supply path and the vent and the porous gas-permeable membrane 13 disposed in the opening thereof so as to face the local exhaust device 4. The flying height of the local exhaust device (local film forming / etching head) 4 is determined by selecting the pressure and flow rate of the compressed gas and the balance of the suction amount by each exhaust means, uniformly emitted toward the table 2. Is done. Levitation stability is also improved by gas viscosity. That is, in the laser processing apparatus 1 according to the present embodiment, the local exhaust device 4 has a static pressure floating pad configuration.

With this static pressure floating pad configuration, the local exhaust device 4 can be displaced relative to the workpiece 3 that is the workpiece on the support 2. With regard to the floating rigidity for static pressure levitation, it is possible to improve the floating rigidity not only by the compressed gas supply means 9 and the exhaust means 10 and 11, but also by the raw material supply means 5, the local exhaust means 6, the purge gas supply means 7, and the like. Become. Here, the floating rigidity is an adsorption force between the local exhaust device 4 and the workpiece, and when the floating rigidity is not sufficient, the height (gap) of the local exhaust device 4 with respect to the workpiece is stabilized. It is preferable to ensure sufficient floating rigidity because of problems such as insufficient performance and insufficient mechanical or mechanical stability of the local exhaust device 4.
When actually performing the machining, the local evacuation device 4 is levitated from the support table 2 to a height that is greater than the thickness of the workpiece 3 by static pressure levitation. When moving at least one of the local exhaust device 4, the workpiece 3 can be smoothly inserted under the local exhaust device 4.

The space formation between the local exhaust device 4 and the support base 2 may not necessarily be based on the static pressure levitation, but the inert gas is stably ejected from the local exhaust device 4 to the support base 2. In addition to levitation, the inflow of outside air to the local exhaust unit 6 and the scattering of vaporized material and dust generated in the local exhaust unit 6 during laser etching to the outside can be reduced by the so-called gas curtain action. Since the cleanliness of the surrounding environment (clean room, etc.) can be maintained, it is considered particularly preferable to use static pressure levitation with an inert gas.
Further, the height of the local exhaust device 4, that is, the flying height from the support base 2, when the porous gas-permeable membrane 13 is made of a porous body having a porosity of 40%, for example, is selected depending on the selection of the ejection amount of the inert gas. Adjustment over a wide range of about μm to 100 μm is possible, but the porosity of the porous gas permeable membrane 13 is not limited to this, and the material of the porous gas permeable membrane 13 is not limited to porous aluminum (Al), and is porous. It is possible to select a desired material from materials such as quality metals, ceramics, and synthetic resins.

FIG. 1B shows a schematic bottom view of the local exhaust device 4 constituting the laser processing apparatus 1 according to the present embodiment.
Then, on the bottom surface of the local exhaust device 4, the compressed gas injected toward the support base 2 side and the surplus of the gas (raw material gas, purge gas, etc.) supplied toward the workpiece 3 are respectively shown. Ring-shaped suction grooves (exhaust flow paths) 15 and 16 for exhausting by the exhaust means 10 and 11 are provided. The above-mentioned local space (local exhaust part 6) faces the bottom surface of the local exhaust device 4 and is transparent inside the substantially concentric ring formed by the suction grooves constituting the ends of the exhaust flow paths 15 and 16. It is formed as a substantially cylindrical space that occupies the height from the window 19 or the transmission hole 20 to the workpiece 3.
In the laser processing apparatus 1 according to the present embodiment, in the laser processing apparatus 1, for example, laser light L from a laser light source apparatus (not shown) is collected by an objective lens or the like, and is locally exhausted through a transmission hole 20 having a transparent window 19. By introducing it into the portion 6, processing such as thin film formation by laser CVD or removal of the thin film by laser etching in the local exhaust portion 6 becomes possible.

On the other hand, a desired value can be selected as the pulse width L of the pulsed laser beam L, but it is preferably 10 picoseconds or less, particularly preferably a pulse width of 1 picosecond or less called a so-called femtosecond laser. It is preferable. When the pulse width is larger than 10 picoseconds, heat accumulates in the irradiated portion of the workpiece 3 and diffuses in the workpiece 3 to melt the periphery of the irradiated portion that should be originally removed. It is because it ends. Since the generation of the melt causes vaporization and dust generation, the irradiation time per one pulse of the laser beam is shortened, so that it is concentrated in a shorter time than the thermal diffusion occurs. Light energy can be supplied to suppress the progress of melting.
The selection of the pulse width is considered to be more preferable in consideration of the target member material. For example, when the object to be removed on the workpiece 3 (for example, a part of the wiring that is excessively formed) is made of aluminum (Al), a pulse having an appropriate pulse width of, for example, about 2 picoseconds to 10 picoseconds is used. It is preferable to select the width.

  Further, a desired value can be selected for the wavelength of the pulse laser beam L. On the other hand, the so-called amount of melting dripping generated by melting around the irradiated portion of the workpiece is determined by the diffraction limit, and the amount of dripping tends to increase as the wavelength increases. Therefore, it is desirable to select a laser beam having a short wavelength in order to reduce the amount of bordering of the laser cut portion. For example, a wavelength of 390 nm or less is suitable.

Here, a schematic operation of the laser processing apparatus 1 shown in FIGS. 1A and 1B in forming a thin film by the laser CVD method will be described.
First, compressed gas is supplied from the compressed gas supply means (supply source) 9 to the compressed gas supply path 14 and is injected to the workpiece 3 through the porous gas permeable membrane 13, and the local exhaust device 4 is predetermined from the workpiece 3. Ascend by the interval and start operation. At this time, a floating stage (not shown) having a thickness substantially the same as that of the workpiece 3 and close to the workpiece 3 is prepared at a position away from directly below the local exhaust device 4. After the local exhaust device 4 placed on the levitation stage is levitated and then subjected to a procedure for moving the local exhaust device 4 onto the workpiece 3, contact is made when the local exhaust device 4 is moved onto the workpiece 3. Can be avoided with certainty.

In this state, the source gas for film formation is supplied from the source supply means (supply source) 5 via the source gas flow path 17, and the purge gas is supplied from the purge gas supply means 7 via the purge gas flow path 18 to the local exhaust section 6. In other words, it is supplied toward the local area on the workpiece 3 to be deposited. As a source gas for film formation, for example, a carbonyl compound (such as tungsten carbonyl W (CO) ₆ ) can be used.
Thereafter, the laser light L from the laser light source device is irradiated to the local area where the object to be processed 3 is to be formed through the transmission hole 20, the transparent window 19 and the local exhaust unit 6, thereby processing the material gas based on thermal decomposition. A CVD film can be formed locally on the object 3.

<Embodiment of Laser Processing Method, Wiring Board Manufacturing Method, and Wiring Board>
Next, an embodiment of the laser processing method according to the present invention will be described. In the present embodiment, a description will be given by taking as an example a case where a wiring board is corrected (manufactured) by laser processing. As the processing apparatus, the laser processing apparatus (wiring board manufacturing apparatus) of the above-described embodiment is used.

In the laser processing method (wiring substrate manufacturing method) according to the present embodiment, a lower layer wiring 21, an interlayer insulating film 22, and an upper layer wiring 23 are stacked as shown in the top view of FIG. 2A and the cross-sectional view of FIG. 2B. In the formed multilayer film, the present invention can be applied to correction when a short-circuit portion (interlayer short) 24 occurs at the three-dimensional intersection of the lower layer wiring 21 and the upper layer wiring 23 due to a defect in the interlayer insulating film 22. That is, a part including the short-circuit portion 24 is laser-etched under a predetermined condition to be removed as a laser cut portion 25 as shown in the top view of FIG. 2A and the cross-sectional view of FIG. This can be applied to the case where the defect correcting portion 26 is formed by embedding the cut portion 25.
Further, the laser processing method (wiring substrate manufacturing method) according to the present embodiment includes a lower layer wiring 31, an interlayer insulating film 32, an upper layer wiring 33, as shown in the top view of FIG. 3A and the cross-sectional view of FIG. 3B. In the multilayer film in which the short circuit portions (interlayer and in-layer short circuit) 34 occur due to the inclusion of foreign matter or the like, the lower layer wiring 31 and the plurality of upper layer wirings 33 are also involved. That is, a part including the short-circuit portion 34 is laser-etched under a predetermined condition to be removed as a laser cut portion 35 as shown in the top view of FIG. 3A and the cross-sectional view of FIG. This can be applied to the case where the defect correcting portion 36 is formed by embedding the cut portion 35.

In the laser processing method according to the present embodiment, first, the compressed gas from the compressed gas supply means 9 is injected to the processing object 3 side through the porous gas permeable membrane 13, and the local exhaust device 4 is predetermined from the processing object 3. Let it rise by an interval. In this state, the laser beam L is irradiated to the region to be etched of the workpiece 3, and a part of the formed thin film pattern (for example, a part of the excessively formed wiring) is removed by laser etching.
At this time, the laser beam L is preferably a pulsed laser beam having a pulse width of 10 picoseconds or less as described above. Further, the wavelength of the pulsed laser light L is selected together with the film thickness and the reflectance of the multilayer film that is the irradiated portion of the workpiece 3, and this wavelength is selected as a laser light source (with the film thickness and the reflectance as necessary). It is preferable to input to the input part interlocked with the part and reflect it in the machining.

  As a specific example, there is a case where laser etching is performed on a multilayer film having a laminated structure as shown in FIG. 4A. That is, the reflectance change corresponding to the film thickness of the silicon nitride (SiN) layer and the silicon oxide (SiO) film corresponding to the interlayer insulating film is measured in advance, and in the visible light region at least at a part of the plurality of wavelengths. Processing is performed by irradiating a multilayer film having a film thickness having a higher reflectance than the average reflectance with a laser beam having a wavelength corresponding to a reflectance higher than the average reflectance.

This specific example will be described in more detail.
First, FIG. 4B shows a simulation result (reflection spectrum) of the reflectance with respect to the interlayer insulating film when the thickness of the silicon nitride layer is 150 nm and the thickness of the silicon oxide layer is 150 nm. Depending on the thickness, the overall shape of the spectrum changes. Under this thickness condition, the reflectance at 390 nm is significantly lower than the average reflectance (41%) in the visible light region. That is, the reflectance is 22%, and the remaining 78% is considered to be absorbed by the Mo layer.
Therefore, under this thickness condition, there is a strong possibility that the molybdenum layer located below the interlayer insulating film is strongly damaged.

On the other hand, when laser etching is performed on a multilayer film having a laminated structure (thickness condition) as shown in FIG. 5A, the reflection spectrum changes as shown in FIG. 5B, and the reflectance at 390 nm becomes a maximum value. Greatly exceeding the average reflectance (44%) in the visible light region. That is, the reflectivity is 64%, and the remaining 36% is considered to be absorbed by the Mo layer, so that the energy absorbed in Mo is less than half compared to the case of the configuration shown in FIG. 4A. Therefore, it becomes possible to suppress the destruction of the lower layer.
Therefore, under this thickness condition, the damage to the molybdenum layer when processing with a pulsed laser beam having a wavelength of 390 nm can be reduced, and a short circuit can be caused while the lower layer wiring remains as shown in FIGS. 2C and 3C. It is thought that correction processing that eliminates it becomes possible.

As the laser energy density, it is preferable to select a value near the threshold energy of the material of the upper wiring. As a material that can be used in the wiring, for example, since the threshold of Mo is the threshold of 0.09J / ^cm 2, Al is considered to 0.08 J / cm ^2, the energy density of these neighboring, i.e. 0.1 J / cm ² The following processing is considered preferable.
In the processing with the energy density higher than this value, there is a possibility that the lower layer destruction phenomenon occurs, and the selective workability may be lost. Further, in the processing with the energy density lower than this value, there is a possibility that the possibility of the upper layer film remaining is increased. Note that the laser cut region is preferably about 1 μm larger than the short-circuited region in order to surely correct the laser cut region.

Furthermore, the laser processing method (wiring substrate manufacturing method) according to the present embodiment includes a lower layer wiring 61, an interlayer insulating film 62, and an upper layer wiring 63 as shown in the top view of FIG. 6A and the sectional view of FIG. 6B. In the multilayer film in which the upper insulating film 67 covering these layers is laminated, the lower layer wiring 61 and the plurality of upper layer wirings 63 are also involved due to the inclusion of foreign matter or the like, and a short circuit portion (interlayer and intralayer short) 64 is generated. Applicable to case correction. That is, a part including the short-circuit portion 64 is laser-etched under predetermined conditions to be removed as a laser cut portion 65 as shown in the top view of FIG. 6A and the cross-sectional view of FIG. This can be applied to the case where the defect correcting part 66 is formed by embedding the cut part 65.
That is, in the laser processing method according to the present embodiment, the short circuit portion (and the upper layer wiring) is covered with the upper insulating film as well as the case where the short circuit portion is exposed as illustrated in FIGS. Even in this case, the present invention can be applied in the form of eliminating the short circuit while suppressing the destruction of the upper insulating film.
In this case, a change in reflectance according to the film thickness of the silicon nitride (SiN) layer and the silicon oxide (SiO) film corresponding to the upper insulating film is measured in advance, and at least part of a plurality of wavelengths is in the visible light region. Processing is performed by irradiating a multilayer film having a film thickness having a low reflectance with respect to the average reflectance with a laser beam having a wavelength corresponding to a reflectance lower than the average reflectance. That is, the wavelength of the laser beam is selected in order to suppress reflection in the upper insulating film having a specific thickness.

This specific example will be described in more detail.
First, as shown in FIG. 7A, a simulation result (reflection spectrum) of the reflectance with respect to the upper insulating film in a laminated structure (thickness condition) in which the thickness of the silicon nitride layer is 200 nm and the thickness of the silicon oxide layer is 100 nm. Is shown in FIG. 7B. Depending on the thickness, the overall shape of the spectrum changes. Under this thickness condition, the reflectance at 390 nm exceeds the average reflectance (50%) in the visible light region. That is, the reflectance is 57%, and the remaining 43% is considered to be absorbed by the Ti layer.
Therefore, under this thickness condition, there is a strong possibility that the titanium layer located below the upper insulating film is difficult to process.

On the other hand, in the upper insulating film having the laminated structure (thickness condition) as shown in FIG. 8A, the reflection spectrum changes as shown in FIG. It is well below the average reflectance (53%). That is, it is considered that the reflectance of the upper insulating film is 9.5%, and the remaining 90.5% is absorbed by the Ti layer (upper wiring). Therefore, in this case, the energy absorbed in the Ti layer occupies more than half of the laser light as compared with the case of the configuration shown in FIG. 8A, so that the selective destruction (selection) of the Ti layer is performed while being covered with the upper insulating film. Removal).
Therefore, under this thickness condition, the energy absorbed by the titanium layer when processing with a pulsed laser beam with a wavelength of 390 nm can be increased, and correction processing that eliminates the short-circuit portion (short) while allowing the lower layer wiring to remain is possible. It is thought that it becomes.

<Embodiment of Manufacturing Method of Display Device>
According to the method for manufacturing a wiring board, which is a specific example of the laser processing method, according to the above-described embodiment, a display device including a liquid crystal display can be obtained by combining the manufactured wiring board and other ordinary members. It is also possible to manufacture a so-called light source device such as a backlight included in the above.

In general, display devices are roughly classified into two types, a direct light method and an edge light (side light) method, depending on the arrangement method of the light source device including the fluorescent tube.
The direct type has a configuration in which a light source device including a plurality of fluorescent tubes is provided on the back surface (back surface) facing the display surface (front surface). Since the light from the light source device can be directly used, it is advantageous for high brightness, high efficiency, and large size, but it is difficult to reduce the thickness and consumes large power.
On the other hand, the edge light system has a configuration in which, for example, an acrylic plate-shaped light guide (light guide) and a light source device are arranged on the back surface facing the display surface. Light is diffused in the light guide, which is advantageous for downsizing, thinning, and low power consumption, but weight is a problem for large screen displays. In addition, the edge light method further includes a backlight type in which the position of the light source device is on the back side of the light guide unit, and the position of the light source device on the surface of the light guide unit on the premise that reflected light is generated in the optical element. It is classified as a front light type.

  The laser processing method according to the above-described embodiment is not limited to any of these methods, and various display devices can be manufactured through the manufacture of the wiring board.

  A specific example of the display device obtained by manufacturing the wiring board described above will be described with reference to FIG.

  The display device 41 includes a light source device 42. A fluorescent tube 47 is provided as a light source in the resin light guide 46 of the light source device 42.

In the present embodiment, a diffusion sheet 49 is provided at the closest portion of the light source device 42 that faces the optical device 43. The diffusion sheet 49 uniformly guides light from the fluorescent tube 47 to the optical device 43 side in a planar shape. A reflector 44 is provided on the back side of the light source device 42. In addition, a reflector 45 similar to the reflector 44 is also provided on the side surface of the light guide 46 as necessary.
In the light source device 42 according to the present embodiment, as the resin constituting the light guide unit 46, various transparent resins can be used in addition to epoxy, silicone, and urethane.

  The display device 41 also includes an optical device (for example, a liquid crystal device) 43 that outputs predetermined output light by modulating light from the light source device 42. The light source device 42 described above is provided on the back surface of the optical device 43, and light is supplied to the optical device 43 from the light source device 42 serving as a so-called direct-type backlight.

In this optical device 43, from the side close to the light source device 42, the deflection plate 50, the glass substrate 51 for TFT (Thin Film Transistor) and the dot-like electrode 52 on the surface thereof, the liquid crystal layer 53 and the front and back thereof. The deposited alignment film 54, the electrodes 55, a plurality of black matrices 56 on the electrodes 55, and first (red) color filters 57a and second (green) corresponding to pixels provided between the black matrices 56. The color filter 57b, the third color filter 57c, the glass substrate 58 provided separately from the black matrix 56 and the color filters 57a to 57c, and the deflection plate 59 are arranged in this order.
Here, the deflecting plates 50 and 59 form light that vibrates in a specific direction. The TFT glass substrate 51, the dot electrode 52, and the electrode 55 are provided for switching the liquid crystal layer 53 that transmits only light oscillating in a specific direction, and an alignment film 54 is also provided. Thus, the inclination of the liquid crystal molecules in the liquid crystal layer 53 is aligned in a certain direction. Further, since the black matrix 56 is provided, the contrast of light output from the color filters 57a to 57c corresponding to each color is improved. The black matrix 56 and the color filters 57a and 57c are attached to the glass substrate 58.

  According to the laser processing method (wiring substrate manufacturing method) according to the above-described embodiment, by using, for example, at least the TFT glass substrate 51 to the electrode 55 by using the obtained wiring substrate, it is possible to make dark spots or dark lines. It is possible to manufacture a light source device and a display device by correcting a portion where there is a risk of conversion. Therefore, according to the light source device and the display device provided with this wiring board, the yield can be improved and the throughput during manufacturing can be shortened.

<Example>
As a specific example of the laser processing method according to the present invention, an embodiment (examination result) of a method of manufacturing a wiring board (array substrate) will be described.

  Using the apparatus shown in FIGS. 1A and 1B, laser processing was performed using a thin film transistor (TFT) substrate as a processing target.

First, an inert gas of argon (Ar) or nitrogen (N ₂ ) supplied from the compressed gas supply means 9 is ejected toward the support base 2 through the porous gas permeable membrane 13 in the local exhaust device 4, thereby locally The exhaust device 4 is higher than the thickness of the object 3 to be processed, for example, 100 μm. Thereby, the contact with the local exhaust apparatus 4 and the process target object 3 in the following process can be avoided including the case where the process target object 3 has some warping and waviness.

  Next, after moving the support table 2 in the horizontal direction and inserting the processing object 3 between the local exhaust device 4 and the support table 2, the height of the local exhaust device 4 is set to 20 μm from the processing object 3, The support table 2 is moved in the horizontal direction so that the short-circuit occurrence location of the workpiece 3 becomes the irradiated portion of the pulse laser beam, and the relative position adjustment between the local exhaust device 4 and the workpiece 3 is performed.

  Next, only 5000 pulses of pulse laser light L having a repetition rate of 100 Hz, a pulse width of 3 picoseconds, and an irradiation beam shape of 10 μm square are output from the pulse laser light source, and the workpiece 3 is irradiated with the laser light through the transparent window 19. went. The laser beam L was shaped by an aperture, and was observed using an irradiation observation unit while observing at an objective lens magnification of 50 times and a working distance of 15 mm.

FIGS. 10A and 10B show micrographs obtained by performing laser processing on the object to be processed in which the reflection characteristics of the lower layer and the interlayer insulating film are as shown in FIG. 4B. From these results, it was confirmed that destruction of the lower layer wiring occurred.
On the other hand, FIGS. 11A and 11B show micrographs obtained by performing laser processing on the object to be processed in which the reflection characteristics of the lower layer and the interlayer insulating film are as shown in FIG. 5B. It was confirmed that only the upper layer could be selectively removed without affecting the lower layer.

In addition, about the wiring board in which the upper layer insulating film was formed on the upper layer wiring (refer FIG. 6A-FIG. 6C), the leakage current between the upper layer wiring in the wiring board after performing the laser processing was measured. The measurement results are shown in FIG. FIG. 12 shows the measurement results in a semi-logarithmic graph in which only the vertical axis is logarithmically displayed.
In the wiring substrate in which the reflection characteristic of the upper insulating film was as shown in FIG. 8B, as a result of trying to remove the short circuit by laser processing, there was no change in the resistance of the upper wiring as shown by the solid line a in FIG. As a result of maintaining a high resistance, the leakage current was suppressed), and it was confirmed that only the upper layer could be selectively removed without affecting the lower layer.
On the other hand, in the wiring board in which the reflection characteristic of the upper insulating film is as shown in FIG. 7B, even after trying to remove the short circuit by laser processing, large-scale current leakage occurs as shown by the solid line b in FIG. It was confirmed that the short circuit could not be removed.

  As described in the above embodiments and examples, according to the laser processing method, the wiring board manufacturing method, and the display device manufacturing method according to the present embodiment, for example, by using the laser processing apparatus described above, The processing (manufacturing) can be performed more simply and reliably than in the past. Therefore, both improvement in yield and reduction in throughput can be achieved.

In addition, according to the laser processing method and the like according to the present embodiment, since generation of interlayer shorts is suppressed, defective products to be discarded are reduced, so that production efficiency can be improved and manufacturing cost can be reduced. .
In addition, the above-mentioned melt is also affected by the bonding properties of the materials constituting the member to be processed. However, particularly in the case of a material having good heat conductivity such as a metal, swell is likely to occur around the processed portion, and the above-described scattering is caused. Since the distance also increases, according to the laser processing method according to the present embodiment, it is possible to achieve special dust reduction when targeting a member having good thermal conductivity.

  In the wiring board thus obtained, the irradiation of the laser beam to the multilayer film composed of two or more layers made of different materials is performed by selecting the wavelength of the laser beam based on the reflectance of the multilayer film. Since it is manufactured by being made, the short circuit is surely removed and the characteristics are improved.

  Note that the numerical conditions such as the materials used, the amount thereof, the processing time, and the dimensions mentioned in the description of the above embodiments are only suitable examples, and the dimensions, shapes, and arrangement relationships in the drawings used for the description are also schematic. Is. That is, the present invention is not limited to this embodiment.

For example, in the laser processing apparatus according to the present embodiment, a decrease in the temperature around the vaporized material generated by laser irradiation causes solidification and reattachment of the vaporized material. By adopting a structure provided with a heating means (not shown), dust generation can be suppressed.
Note that this heating can be performed by configuring the laser processing apparatus 1 with a heater inside or outside the local processing head 3 or the support base 4, for example. The heating temperature is preferably, for example, about 200 ° C. so as not to give an excessive thermal burden to the porous ventilation means 35 and the member 5 described above, and the local processing head 3 itself is subjected to similar heating. By applying, it is possible to avoid a temperature drop of the member or the inert gas.

  Further, the interlayer insulating film is not limited to the configuration shown in FIGS. 4A, 5A, 7A, and 8A, and the number of layers may vary, but the reflection of the multilayer film composed of the lower layer wiring and the interlayer insulating film may occur. By optimizing the film thickness of each layer in order to match the rate to the maximum peak at the laser wavelength to be used, the optimum processing conditions can be selected as in this embodiment.

  In addition, in a workpiece having an upper insulating film, the stacked structure (number of layers, materials, etc.) of the upper insulating film is not limited to that described above. In other words, in the processing (manufacturing) of an object having an upper insulating film having a laminated structure different from that described above, the reflectance of both the multilayer film including the upper wiring and the upper insulating film thereon is used. By optimizing the film thickness of each layer in order to match the minimum peak at the laser wavelength to be used, the present invention can select various optimum conditions for processing as in the present embodiment. Changes can be made.

A and B are respectively a schematic configuration diagram showing a configuration of an example of a laser processing apparatus according to the present invention and a bottom view of a local exhaust device. AC is each explanatory drawing with which description of the laser processing method which concerns on this invention is provided. AC is each explanatory drawing with which description of the laser processing method which concerns on this invention is provided. Each of A and B is a schematic diagram showing a configuration of an example of a multilayer film, and an explanatory diagram showing a reflection spectrum in this configuration. Each of A and B is a schematic diagram showing a configuration of another example of a multilayer film, and an explanatory diagram showing a reflection spectrum in this configuration. AC is each explanatory drawing with which description of the laser processing method which concerns on this invention is provided. Each of A and B is a schematic diagram showing a configuration of another example of a multilayer film, and an explanatory diagram showing a reflection spectrum in this configuration. Each of A and B is a schematic diagram showing a configuration of another example of a multilayer film, and an explanatory diagram showing a reflection spectrum in this configuration. It is explanatory drawing with which it uses for description of a display apparatus. Each of A and B is a microscopic observation photograph of the processing result for explaining the laser processing method according to the present invention. A and B are microscopic observation photographs of processing results in an example of the laser processing method according to the present invention. It is explanatory drawing with which it uses for description of the measurement result of leakage current.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Laser processing apparatus, 2 ... Support stand, 3 ... Processing object (board | substrate), 4 ... Local exhaust apparatus (local film-forming / etching head), 5 ... Raw material supply means, 6 ... Local exhaust part (local processing part), 7 ... Purge gas supply means, 8 ... Floating stage, 9 ... Compressed gas supply means, 10 ... Exhaust means, 11 ... Exhaust means , 12 ... Orifice forming member, 13 ... Porous membrane, 14 ... Compressed gas supply passage, 15 ... Exhaust flow path (suction groove), 16 ... Exhaust flow path (suction groove) ), 17 ... Raw material gas flow path, 18 ... Purge gas flow path, 19 ... Transparent window, 20 ... Transmission hole, 21, 31, 61 ... Lower layer wiring, 22, 32, 62 ..Interlayer insulating film, 23, 33, 63... Upper layer wiring, 24, 34, 64... Short circuit part, 25, 35, 65. Zaccut part, 26, 36, 66 ... Defect correction part, 41 ... Display device, 42 ... Light source device, 43 ... Optical device, 44 ... Reflector, 45 ... Reflector, 46 ..Light guide unit, 47... Fluorescent tube, 49... Diffusion sheet, 50 .. Deflection plate, 51... TFT glass substrate, 52. ... Alignment film, 55 ... Electrode, 56 ... Black matrix, 57a ... First color filter, 57b ... Second color filter, 57c ... Third color filter, 58 ... Glass substrate, 59 ... deflection plate, 67 ... upper insulating film

Claims (12)

At least a support base that supports a workpiece, a local exhaust device that introduces laser light toward a local exhaust section where pressure is locally adjusted on the support base, and a laser light source section that outputs the laser light A laser processing apparatus comprising:
The local exhaust device is capable of ascending relatively from the support table by injecting levitation gas to the support table,
The workpiece has at least a multilayer film composed of two or more layers made of different materials.
An input unit to which the reflectance of the object to be processed is input is connected to the laser light source unit. A laser processing method for irradiating a workpiece with laser light,
The laser processing method, wherein the wavelength of the laser beam is selected based on a reflectance of a multilayer film composed of two or more layers having different materials in the processing object. In advance, for a plurality of wavelengths of the laser light, measuring the change in reflectance according to the thickness of the multilayer film,
In at least some of the plurality of wavelengths, the thickness of the multilayer film is selected so that a wavelength that exhibits a higher reflectance than the average reflectance in the visible light region is generated,
The laser processing method according to claim 2, wherein processing is performed by irradiating the multilayer film with laser light having a wavelength corresponding to a reflectance higher than the average reflectance. In advance, for a plurality of wavelengths of the laser light, measuring the change in reflectance according to the thickness of the multilayer film,
In at least some of the plurality of wavelengths, the thickness of the multilayer film is selected for the thickness at which the maximum value of reflectance is generated,
The laser processing method according to claim 2, wherein processing is performed by irradiating the multilayer film with laser light having a wavelength corresponding to the maximum value. The laser processing method according to claim 2, wherein the laser beam is a pulsed laser beam having a pulse width of 10 picoseconds or less. The laser processing method according to claim 2, wherein the laser beam is a pulsed laser beam having an energy density of 0.1 J / cm ² or less per pulse. The laser processing method according to claim 2, wherein the multilayer film is a three-dimensional intersection where different conductive members three-dimensionally intersect via an insulating film. The workpiece has an upper insulating film on the multilayer film,
In advance, for a plurality of wavelengths of the laser beam, to measure the change in reflectance according to the film thickness of the upper insulating film and the multilayer film,
In at least a part of the plurality of wavelengths, the thickness of the upper insulating film and the multilayer film is selected to a thickness at which a wavelength exhibiting a lower reflectance than the average reflectance in the visible light region is generated,
The laser processing method according to claim 2, wherein processing is performed by irradiating the upper insulating film and the multilayer film with a laser beam having a wavelength corresponding to a reflectance lower than the average reflectance. The workpiece has an upper insulating film on the multilayer film,
In advance, for a plurality of wavelengths of the laser beam, to measure the change in reflectance according to the film thickness of the upper insulating film and the multilayer film,
In at least some of the plurality of wavelengths, the thickness of the upper insulating film and the multilayer film is selected for the thickness at which the minimum value of the reflectance is generated,
The laser processing method according to claim 2, wherein processing is performed by irradiating the upper insulating film and the multilayer film with laser light having a wavelength corresponding to the minimum value. A method of manufacturing a wiring board by laser processing,
In manufacturing the wiring board,
Irradiation of laser light to a multilayer film composed of two or more layers of different materials constituting the wiring board, and the wavelength of the laser light is selected based on the reflectance of the multilayer film A method for manufacturing a wiring board. A method of manufacturing a display device including a wiring board,
Manufacturing the wiring board,
The display is performed by selecting the wavelength of the laser beam to be irradiated to the multilayer film based on the reflectance of the multilayer film composed of two or more layers which are different from each other in the wiring board. Device manufacturing method. A wiring produced by irradiating a multilayer film composed of two or more layers having different materials from each other by selecting the wavelength of the laser beam based on the reflectance of the multilayer film. substrate.