WO2004110693A1

WO2004110693A1 - Laser beam machining method and laser beam machining device

Info

Publication number: WO2004110693A1
Application number: PCT/JP2004/008575
Authority: WO
Inventors: Satoshi Jibiki; Kazuya Fujino; Hirohiko Iwase; Takuji Goda
Original assignee: Nippon Sheet Glass Co., Ltd.
Priority date: 2003-06-12
Filing date: 2004-06-11
Publication date: 2004-12-23
Also published as: JP2005000952A

Abstract

When a laser beam is shaped to a rectangle in section by using a mask having a rectangular opening, a laser energy efficiency is low and therefore a large-output laser oscillator is required. When a laser beam is applied onto a tin oxide film (10) spread on a glass substrate (9) to effect electrode patterning, the sectionally circular shape of a beam from a laser oscillator (4) is shaped to an almost rectangle by disposing, as a set of two lenses, cylindrical lenses (5a, 5b) in a mutually orthogonal directions on a laser beam path. The shaped laser beam is applied onto a conductive film using a scanning system as a combination of a refletion mirror (15) and an fθ lens (7).

Description

TECHNICAL FIELD The present invention relates to a method and laser processing for removing a part of a thin film coated on a substrate by irradiating a laser beam and patterning it into a thin film electrode having a predetermined shape. Relates to the device. In particular, the present invention relates to electrode processing of transparent conductive films such as plasma display panels, solar cells, touch panels and the like in which tin oxide is used as an electrode material. BACKGROUND ART A tin oxide film is superior in heat resistance and chemical resistance compared to an IT0 film, and is therefore used as a transparent electrode in a product having a heat treatment process at a high temperature, for example, a plasma display panel. However, in order to apply a tin oxide film that has been uniformly coated on a glass substrate in advance to a predetermined electrode shape, it is necessary to remove a part thereof. Such electrode processing is performed by a photolithography etching technique in which a photoresist is transferred and exposed with a mask formed in accordance with the shape of the electrode, and excess portions are removed by etching. In addition, a photoresist is applied to a glass substrate in advance, and the resist corresponding to the electrode portion is removed by mask transfer exposure in the same manner as described above, and a tin oxide film is formed on the glass substrate in this state by a CVD film forming method. A so-called lift-off method is known in which adhesion is performed and then the remaining resist is removed. The photolithographic etching process described above requires a large number of processes and equipment, especially when applied to relatively large glass substrates such as plasma displays, making equipment larger and using process solutions and resists with longer lead times. There are problems to be solved such as environmental problems related to waste liquid treatment due to the increase in volume. In order to solve the above problem, a method of evaporating and removing an excess film by laser irradiation is described in Japanese Patent Laid-Open No. 2 00 0-3 4 8 6 11 (Patent Document 1). . That is, N d: A laser beam emitted from a Y AG laser light source is passed through a mask having an aperture hole, the beam cross-sectional shape is shaped into a substantially rectangular shape, and the beam is irradiated while scanning on an oxide film. This is a method of processing a film with an electrode. Patent Document 1: Japanese Patent Laid-Open No. 2 00 0-3-4 8 6 1 1 and Japanese Patent Laid-Open No. 9 1 0 8 8 7 9 (Patent Document 2> describes processing by irradiating a workpiece with a laser beam. There is disclosed a laser processing apparatus that performs cutting processing by partial melting of an object, which uses two pairs of cylindrical lenses to reverse the energy density distribution of a laser beam with respect to a plane including the beam axis. In other words, a means for increasing the laser beam having a Gaussian distribution whose energy density distribution is highest at the center of the beam axis and decreases toward the outside from the axis, and lower at the center and increases toward the outside. Patent Document 2: Japanese Patent Application Laid-Open No. 9-108879 The laser beam is applied to a plasma display panel by using a pair of cylindrical lenses. When processing multiple striped tin oxide electrodes by evaporating a part of the tin oxide film, the laser beam is moved in a linear direction. The energy density distribution is the highest at the center of the beam axis and has a so-called Gaussian distribution that decreases as it goes outward, so the laser beam emitted from the laser oscillator is simply irradiated one after another onto the tin oxide film. By irradiating while shifting the position, a large amount of heat of the laser beam is applied to the center part in the width direction of the substrate exposed part (interelectrode insulating part) between the electrodes to be formed. The amount of heat applied to the outer edge of the beam diameter, that is, near the end of the electrode to be formed must be small, so the end of the electrode must be sharp. There was a technical problem that it was not processed or the conductive film was not completely removed at the interelectrode insulating part, and electrical insulation between the electrodes could not be obtained with certainty.

2

Blinking paper chain When the energy density is increased to the outer edge of the laser beam diameter to solve this problem, excessive thermal energy is applied to the surface of the workpiece at the center of the laser beam axis, causing damage due to melting, evaporation, etc. There was a problem that occurred. In order to solve such a problem, in the prior art described in Japanese Patent Laid-Open No. 2 00 0-3 4 8 6 11 1, a circular laser beam emitted from a laser oscillator is provided in the optical path. A method is disclosed in which a part of the mask plate is passed through a rectangular opening hole and the beam cross-sectional shape is shaped into a rectangle. However, in this method, a considerable part of the emitted laser beam is shielded by the mask plate, and only the energy near the axis center of the laser beam contributes to the electrode processing. In order to realize electrode processing for ensuring insulation and electrode processing performed in a short time, there is a problem that a large power and therefore an expensive laser oscillator is required. Japanese Patent Application Laid-Open No. 9-108879 discloses a laser processing apparatus that can change the energy density distribution in the cross-sectional direction of a laser beam. However, the cross-sectional shape of the beam obtained by combining a pair of cylindrical lenses is circular, and is intended to prevent dross adhesion. An object of the present invention is to solve the above-mentioned problems and to provide a laser processing method of an electrode for removing a part of a tin oxide film coated on a substrate and a laser processing apparatus capable of suitably performing the same. And DISCLOSURE OF THE INVENTION According to Claim 1 of the present invention made to solve the above-described problems, a conductive film on a substrate is irradiated with a laser beam emitted from a laser oscillator, and the laser beam and the substrate are made relative to each other. The conductive film is laser-processed into an electrode having a predetermined shape by moving the conductive film in an optical lens group. The laser processing method is characterized in that it is shaped into a substantially rectangular shape by optical means. According to claim 1, since the laser beam applied to the conductive film is formed into a substantially rectangular shape by the optical means including the optical lens group, the cross-sectional circular shape of the beam emitted from the laser oscillator is shaped. Part of the beam is not physically blocked. This makes it possible to maintain high use efficiency of the laser beam energy. Also, since the shape of the laser beam applied to the conductive film is almost rectangular, when the striped electrode is processed by sequentially shifting the beam irradiation point on a straight line, there will be a place where no irradiation (irradiation leakage) occurs. Therefore, electrical insulation between the electrodes can be reliably ensured. A second aspect of the present invention provides the optical means according to the first aspect, wherein the optical means is a set of two lens groups in which a plurality of cylindrical lenses are arranged in a direction orthogonal to each other, and are arranged apart from each other in the beam axis direction of the laser beam. It is characterized by comprising an optical system. According to claim 2, the size of the cylindrical lens may be a size that allows the laser beam to pass through without being lost. Since the laser beam is usually a few millimeters in diameter, the cross-sectional shape of the laser beam can be shaped with a small optical system. Claim 3 is characterized in that, in claim 1 or 2, the maximum energy density in the cross-sectional direction of the laser beam to be irradiated is leveled so as not to exceed twice the minimum value. According to claim 3, the energy density is leveled so that the maximum value of energy does not exceed twice the minimum value of energy. The film is also properly removed at the location, and the occurrence of electrical insulation failure due to insufficient local removal of the conductive film is suppressed, so that the electrode can be processed reliably. Claim 4 is according to any one of claims 1 to 3, wherein the wavelength of the laser beam to be irradiated is in the range of 3500 nm to 20:00 nm, and the energy density is distributed within the range of 8 to 16 Jcm2. You It is characterized by being shaped as follows. According to claim 4, by setting the wavelength of the laser to 3500 nm to 200 nm, the surface of the glass plate coated with the conductive film is not deteriorated and deteriorated, but the tin oxide film or the oxide film is used. A film containing tin as a main component (such as a tin oxide film containing indium, a tin oxide film containing antimony, or a tin oxide film containing a halogen element such as fluorine or chlorine) can be removed. In addition, by ensuring that the density distribution of the irradiated laser beam in the energy cross-sectional direction is within the range of 8 to 16 j Z cm2, electrical insulation can be ensured. A fifth aspect of the present invention is characterized in that in any one of the first to fourth aspects, the conductive film is a conductive film in which a tin oxide film is laminated and coated on a silicon dioxide film. A sixth aspect of the present invention is characterized in that, in any one of the first to fourth aspects, the conductive film is a conductive film in which a tin oxide film, a silicon dioxide film, and a tin oxide film are laminated and coated in this order. The tin oxide film is used to increase the adhesion with the glass substrate, or to adjust the color tone of the film, to reduce its electrical resistivity, and to form a silicon dioxide film, or a tin dioxide film and silicon dioxide. Two layers of the film may be coated as a base film, and even a film having such a laminated structure can be processed in the same manner as a film of a single layer of tin oxide. Moreover, even if an insulating protective film such as titanium oxide or zirconium oxide is coated on the tin oxide film, the electrode can be processed in the same manner as the single tin oxide film. The laser processing apparatus according to claim 7, wherein the workpiece is processed by irradiating the workpiece with a laser beam emitted from a laser oscillator, wherein a cross-sectional shape of one laser beam is approximately between the laser oscillator and the workpiece. A laser processing apparatus comprising optical means including an optical lens group for shaping into a rectangle. According to claim 7, the cross-sectional shape of the laser beam is set between the laser oscillator and the workpiece. Since the optical means composed of the optical lens group shaped into a substantially rectangular shape is provided, a part of the laser beam emitted from the laser oscillator is not physically shielded. As a result, laser energy can be used effectively, and a lower-power laser oscillator can be used. Claim 8 is the optical means according to claim 7, wherein two optical lens units are arranged in a direction perpendicular to each other in a direction perpendicular to each other, and two lens groups are arranged apart from each other in the beam axis direction of the laser beam. It is characterized by comprising the above optical system. According to claim 8, the optical group is configured by an optical system in which a plurality of cylindrical lenses are arranged in a direction orthogonal to each other and separated in pairs in the axial direction of the laser beam. Therefore, shaping the cross-sectional shape of the beam from a circle to a rectangle can be configured with small optical components. Claim 9 is the oscillation laser according to claim 8, wherein the focal length of the cylindrical lens is f mm, the radius of curvature of the cylindrical lens is r mm, and the distance between one lens group and the other lens group is L mm, When the beam diameter is d mm, the following relationship is satisfied.

f <L≤ 2 f

0.5 d <r ≤ 6 d Claim 10 is the structure according to any one of claims 7 to 9, wherein a beam staging system including a reflecting mirror and an fΘ lens is provided between the optical means and the workpiece. It is characterized by that. According to claim 10, since the beam scanning system including the reflection mirror and the f Θ lens is provided between the optical means and the workpiece, it can be placed anywhere on the tin oxide film coated on the substrate. It is possible to irradiate a beam with the same shape and size. As a result, it is possible to perform electrode processing with accurate dimensions. Brief Description of Drawings FIG. 1 is a diagram for explaining a laser processing apparatus according to the present invention.

FIG. 2 is a schematic diagram for explaining an embodiment of the laser beam shaping system 5 according to the present invention.

FIG. 3 is a view for explaining irradiation of a conductive film with a laser beam according to the present invention. FIG. 4 is a plan view of an example of a glass substrate with an electrode obtained by the laser processing method of the present invention.

FIG. 5 is a diagram showing a cross-sectional shape and an energy density distribution of an example of a laser beam according to the present invention.

FIG. 6 is a detailed view of an embodiment of the energy density distribution of the laser beam according to the present invention.

FIG. 7 is a detailed view of another embodiment of the energy density distribution of the laser beam according to the present invention.

Fig. 8 is a schematic diagram of (a) the leveled energy density distribution of the laser beam and the electrode processed by the laser beam. (B) is the electrode processed by one laser beam emitted from the laser oscillator. FIG. BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram for explaining a laser processing apparatus 1 of the present invention. The laser processing apparatus according to the present invention has an optical system 2 and a scanning system 3. Above the worktable 8, an optical system 2 having a laser oscillator 4 that periodically oscillates a laser beam is arranged. The laser beam 'emitted from the laser oscillator 4 is arranged in combination with a cylindrical lens, enters the laser beam shaping system 5, and the beam shaping system 5 shapes the cross-sectional shape of the laser beam into a substantially rectangular shape. 3 leads =>. In the present invention, the optical system 2 includes at least a laser oscillator 4 and a laser oscillator 4. And a laser beam shaping system 5 combined with a cylindrical lens that shapes the cross-sectional shape of the irradiated laser beam into a substantially rectangular shape. As the laser oscillator 4, for example, an Nd-YAG laser can be suitably used. The laser beam emitted from the laser oscillator 4 is usually circular in cross section, and the energy density distribution in the laser beam cross section is Gaussian distribution, that is, the highest energy at the center of the beam axis, and the energy decreases toward the outside of the beam. . The laser beam shaping system 5 suitably used in the present invention has two lens groups 5 a and 5 b in which two cylindrical lenses are arranged in a direction perpendicular to each other, and two sets are separated from each other in the laser beam axial direction. Consists of an optical system. The laser beam having a circular cross section emitted from the laser oscillator 4 is shaped into a rectangular cross section by the laser beam shaping system 5 with almost no energy loss. In addition, the energy density distribution of the laser beam can be leveled by appropriately selecting and setting the focal length of each cylindrical lens and the separation distance of the lens groups 5a and 5b. In order to further level the energy density distribution of the beam shaped into a substantially rectangular cross section by the laser beam shaping system 5, a mask having a rectangular aperture for shielding mainly the outer edge of the shaped beam is provided. Also good. The laser beam that has passed through the laser beam shaping system 5 is guided to a scanning system 3 having at least a reflection mirror 15 and a high lens 7. The reflection mirror 15 is for changing the propagation direction of the laser beam, and FIG. 1 shows a state in which a polygonal polygon mirror as the reflection mirror 15 is driven by the galvano scan 6. Instead of the polygon mirror mirror, a flat mirror having a translational movement mechanism may be used. The laser beam whose direction has been changed in a certain direction by the reflecting mirror 15 can be used to prevent distortion of the beam shape and blurring of the beam end face even if the irradiation position of the laser beam is changed by the fΘ lens 7. Become. In the present invention, the beam size is reduced from about 1/5 to about 1/30 with the f0 lens. The worktable 8 is installed so that the surface thereof is horizontal, and is connected to a motor (not shown) via a drive mechanism (not shown) (for example, a mechanism including a screw shaft and screw, or a belt and a pulley). The motor can be moved back and forth in the horizontal direction X or in the horizontal direction Y perpendicular to the X direction. FIG. 2 is a diagram for explaining an embodiment of a laser beam shaping system 5 comprising a combination of cylindrical lenses used in the present invention. In a set of two lenses 5a installed upstream of the laser beam, the cylindrical lenses 3 and 4 are both arranged with the cylindrical surface facing the direction of travel of the laser beam. The flat surface of the cylindrical lens that faces the cylindrical surface is perpendicular to the laser beam traveling direction, and the vertical direction of the entire cylindrical surface is the X direction in the figure. The cylindrical lens 4 has the same shape and shape as the cylindrical force lens, and the direction of the cylindrical lens 3 is orthogonal. The lens group 5 b is the same as the lens group 5 a and has the same arrangement with respect to the laser beam. The lens groups 5a and 5b are spaced apart by a certain distance L mm. For cylindrical lenses 1 to 4, the focal length f mm and the radius of curvature r mm of the cylindrical lens can have the same value. When the diameter of the laser beam incident on the cylindrical lens 4 is dmni, the following relationship is preferably satisfied.

f <L≤ 2 f

0.5 d <r≤ 6 d

The reason is that if the separation distance L is smaller than the focal distance f, the energy of the laser beam becomes difficult to level, and if L is larger than 2 f, the laser beam diverges without being converged, which is inconvenient. Also, if the radius of curvature r is less than 0.5 d, the laser beam will leak from the lens, which is inconvenient. If it is greater than 6 d, the effect of lens aberration will be lost, and the energy of the laser beam will be leveled. Since it disappears, it is not preferable. In order to further level the laser beam, a more preferable range is 1.2 f ≤ L and L ≤ 1.5 f. In addition, 0.5 d <r and r≤2.5 d. Next, a process of processing the conductive film coated on the glass substrate into an electrode using the laser processing apparatus 1 of the present invention will be described. As a conductive film to which the laser processing of the present invention can be suitably applied, an acid-tin film or an acid-tin film containing tin oxide as a main component (subcomponents such as indium oxide, acid antimony, chlorine, fluorine, etc.) In addition, a transparent conductive film such as an indium oxide film, an indium oxide film (ITO film), and a zinc oxide film containing aluminum can be listed. In addition to a conductive film in which these films are covered with a single layer on a glass substrate or the like, a laminate of a plurality of films, for example, a silicon dioxide film / tin oxide film, a tin oxide film, a non-silicon oxide film, a tin oxide film The present invention can also be applied to a laminate having such a base film. A glass substrate 9 coated with a tin oxide conductive film 10 as a workpiece is placed on a work table 8 and fixed. For example, the work table 8 is moved in the X direction and a laser beam is irradiated to evaporate and dissipate the conductive film 10 in the X direction to create a region without the conductive film, thereby electrically insulating the conductive film 10. State. Further, moving the work table 8 in the Y direction or operating the reflection mirror 15 shifts the laser beam irradiation position in the Y direction by a certain dimension, and removes the conductive film by the same operation. Thus, one stripe-shaped electrode is formed and processed. By repeating this operation, a large number of strip electrodes in the row direction (or column direction) are processed. The energy density of the laser beam irradiated onto the conductive film is about 8 jZ at the laser beam irradiation point in the case of a tin oxide conductive film with a thickness of about 200 nm, which is usually used as an electrode for a plasma display. c m2 or more is preferable. At this time, the laser oscillation (on and off) and the movement of the work table 8 and / or the angle changing operation of the reflecting mirror 6 are controlled synchronously. FIG. 3 is a diagram for explaining in more detail the situation in which the tin oxide film is irradiated with a laser beam and the tin oxide film is patterned into a strip-shaped tin oxide electrode 10 in the present invention. The laser beam irradiated onto the tin oxide film is shaped into a substantially rectangular cross section without losing a large amount of energy by the laser beam shaping system 5 and is irradiated onto the conductive film 10. The irradiated tin oxide film is heated and removed from the glass surface by evaporation. The area from which the film is removed by one irradiation (one shot) 11 is an approximately rectangular shape that is approximately the size of the laser beam. The region 11 is moved downward in FIG. 3 (that is, the longitudinal direction of the stripe electrode to be formed), and the next irradiation is performed. By sequentially moving the irradiation point downward, an electrically insulating region 12 having no tin oxide film is formed in the vertical direction, and at the same time, a strip electrode having a longitudinal direction in the vertical direction is formed. In FIG. 3, region 12 is a region where the conductive film has already been removed by irradiating the laser beam, and region 13 indicates a region where the laser beam will be scanned. FIG. 4 shows an example of a glass substrate with a patterned electrode of tin oxide obtained by the laser processing method of the present invention. A tin oxide electrode 10 is patterned on one surface of the glass substrate 9, and the tin oxide electrode 10 is in a central rectangular region 14 surrounded by a predetermined region extending along the periphery of the glass substrate 1. Many striped (bar) electrodes are arranged in parallel. One electrode has a certain distance from the adjacent electrode and is electrically insulated. For example, a tin oxide conductive film formed by a known sputtering method or CVD method can be used. For example, a glass substrate with a silicon dioxide film of about 20 nm as a base film and a tin oxide film of about 200 nm on it is used, and the electrode width is 2 00 to 400 μm, between the electrodes Electrodes with a distance of 30 to 100 μm can be processed. FIG. 5 is a diagram showing a cross-sectional shape and energy density distribution of an irradiation laser beam used for laser processing of the present invention. By the laser beam shaping system, the circular beam is shaped into a substantially rectangular shape with virtually no energy loss, and the energy density distribution is leveled from the center of the beam axis to the outside. In Fig. 5, the outer edge of the beam has a slightly higher energy density than the inside. By irradiating the conductive film with such a laser beam and moving the irradiation point sequentially, the end face of the patterned electrode is as shown in the lower cross-sectional view of Fig. 8 (a). The electrode ends (edges) have a relatively sharp shape, and electrical insulation between the electrodes can be ensured Fig. 6 shows the cross-sectional rectangular laser beam obtained by the laser beam shaping system 5 according to the present invention. It is a figure which shows an example of energy density distribution. This is an example when the distance is 6 · 35 mm and the separation distance is 1 Omm. The laser beam is a square with a side length of about 2.4 mm, and it can be seen that the energy density is leveled inside the beam (near the axis center). The outer edge of the beam has a slightly higher energy density than the inner part, the outermost part has the maximum energy density, and the axial center has the minimum energy density. The maximum energy density considered in the cross-sectional direction of the laser beam shown in Fig. 5 is 2.0 times the minimum value. For a laser beam with an energy density distribution as shown in Fig. 6, a high-density energy density at the outer edge of the beam can be obtained by installing a square mask of a predetermined size after the laser beam shaping system 5. By cutting (shielding) the part with, the energy density can be leveled up to about 0.6 5 + 0.55 = 1.2 times the minimum value without generating a large energy loss. FIG. 7 is a diagram showing another example of the energy density distribution of a laser beam having a rectangular cross section obtained by the beam shaping system 5 according to the present invention. This is an example when the focal length of the cylindrical lens is 6.35 mm and the separation distance is 7.4 mm. The laser beam is a square with a side length of about 2.4 mm. The outermost side has the maximum energy density, and the energy density is distributed on the parabola inside the beam (at and near the axis). You can see that you have it. It can be seen that this laser beam is leveled to a maximum / minimum ratio of 1.8 times. It can be seen that the laser beam shaping system 5 of the present invention can be shaped with little energy loss even when used in combination with a physical beam shaping means of shielding the beam. In the present invention, the energy density distribution of the irradiated laser beam is preferably set within the range of 8 to 16 J / cm2 (maximum / minimum ratio is 2.0 times or less). It is preferable to set within the range of ~ 16 jZcn ^ (the ratio of maximum value Z minimum value is 1.5 times or less), and set within the range of 1 3 to 16 jZcmS (maximum value minimum ratio) Is preferably about 1.3 times or less). If the energy density of the irradiated laser beam is less than 8 j / cm2, it is difficult to evaporate and remove the conductive film almost completely without any residue, especially when processing a low-resistance electrode with a thick film. . When the energy density is greater than 16 j Z cm2, it is not preferable because the dissipated conductive film is reattached to the glass substrate, and electrical insulation between the electrodes cannot be ensured. The cross-sectional shape of the laser beam shown in FIG. 6 and FIG. 7 is a substantially square shape with a side of about 2.2 mm. This beam is formed by a ί Θ lens and has a side of several 10 to several 1 0 0 μπι It is narrowed down to. FIG. 8 (b) shows the energy density distribution of the laser beam without using the laser beam shaping system 5 according to the present invention. The cross-sectional energy density of the laser beam emitted from the laser oscillator has a Gaussian distribution. When this laser beam is irradiated as it is, as shown in the lower part of Fig. 8 (b), the removal of the conductive film proceeds at the center part between the electrodes 10 and 10, but the film removal ability at the extreme part is small. It is difficult to ensure electrical insulation. The wavelength of the laser beam used is preferably such that the absorption coefficient at the wavelength of the conductive film to be patterned is larger than the absorption coefficient of the glass substrate. The wavelength range of the oscillation laser is 3 5 0 nn! The time is selected in the range of ~ 200 nm. Examples of the substrate material that can be used in the laser processing of the present invention include glass and ceramics. As the glass, amorphous glass such as aluminoborosilicate glass, aluminosilicate glass, alkali-free glass, soda lime silicate glass, or crystallized glass can be used. Hereinafter, the present invention will be described in detail by way of examples. Example 1 An Nd_Y AG laser (wavelength: 1064 nm, laser beam diameter: 5 mni) was used as the laser oscillator, and the laser beam emitted from the laser oscillator was guided to the laser single beam shaping system shown in Fig. 2. In other words, two cylindrical lenses with a focal length of f = 1.8.9 5 mm were arranged orthogonally to form one lens group, and these two lens groups were spaced apart (distance Lmm) in the beam axis direction. The two cylindrical lenses constituting one lens group were fixed in close contact with each other, and the separation distance L was set to 24.9 mm. The laser beam emitted from this laser beam shaping system is passed through the reflecting mirror and ί Θ lens to the glass substrate (weight composition: Si 026 2.0%, A 12033.2%, ZrO20. 4% , N a202. 1%, K2010. 1%, MgO 6.8%, C a O 3.4%, SrO 1 1.8%, B a O 0.2%) 200 nm thick conductive film (resistance: 50 Ω / square) coated by a chemical vapor deposition method). By moving the reflecting mirror with a galvanometer, a laser beam with an average energy density of 10 J / cm2 with a square of 50 μm on each side is moved on the tin oxide film on the glass substrate while moving the irradiation position. A part to be an insulating part between the electrodes was formed. Thereafter, the laser beam position was shifted by about 300 m and the same processing operation was performed to form and process a striped electrode having an electrode width of 300 μπι and an interelectrode distance of 50 / m. As shown in Fig. 6, the energy density distribution of this laser beam has an outer ring-shaped convex shape at the outer edge of the beam, which is leveled near the center, and is measured by a beam profiler. The maximum value was 16 j / cm2, the minimum value was 8 JZCH12, and the ratio was 2.0. When the electrical insulation state of the portion where the tin oxide film was removed by evaporation by laser beam irradiation (interelectrode insulation) was measured with a commercially available resistivity meter as the interelectrode resistance value, the resistance was 10 Ω or more. In addition, when the interelectrode insulating part was observed with an optical microscope, no foreign matter that was thought to be the residue of the conductive film was observed. The above insulation resistance value is a value that sufficiently satisfies the insulation resistance value required as a row electrode or a column electrode of a substrate with a transparent electrode used in a plasma display or a liquid crystal display device. Example 2 By changing the separation distance and focal length of the cylindrical lens, the average energy density as shown in Fig. 7 is leveled in a convex shape, and the outer edge has an outer ring-shaped convex shape. 14 As in Example 1, except that a laser beam of j / cm2 (minimum value of 1 3 JZ cm2, maximum value of 16 JZ cm2 and the ratio is 1.2 to 3 times) was irradiated. Electrode processing was performed. When the electrical insulation state of the part where the tin oxide film was removed by evaporation by laser beam irradiation (interelectrode insulating part) was measured with a commercially available resistivity meter as the interelectrode resistance value, the resistance was 1 Ω or more. It was. Further, when the interelectrode insulating portion was observed with an optical microscope, no foreign matter that was considered to be the residue of the conductive film was observed. Example 3 By changing the separation distance, focal length, and laser oscillation power of the cylindrical lens, the center of the laser beam as shown in the energy density distribution diagram of Fig. 7 is leveled in a convex shape, and the outer ring-shaped convex shape is formed on the outer edge. As in Example 1, except that an average energy density of 19 jZcm2 (minimum value 1 Ί / cm2, maximum value 2 2 j / cm2 and the ratio is 1.3 times) was irradiated. Electrode processing was performed. When the electrical insulation state of the inter-electrode insulation part was measured with a commercially available tester as the inter-electrode resistance value, the resistance was around 1 ΟΩ. When the interelectrode insulating portion was observed with an optical microscope, some foreign matters considered to be the residual conductive film were observed. Comparative Example 1 Changing the laser oscillation power, the average energy density with the center of the beam leveled in a convex shape as shown in the energy density distribution diagram in Fig. 7 and the outer ring shaped convex shape on the outer edge 6 Electrode processing was performed in the same way as in Example 1 except that a beam of J / cm2 (minimum value 5 j / cm2, maximum value 7 J, cm2 and the ratio was 1.4 times) was irradiated. When the electrical insulation state of the interelectrode insulating portion was measured with a commercially available tester as the interelectrode resistance value, it was several tens of Ω to 10 Ω Ω When the interelectrode insulating portion was observed with an optical microscope, the conductive film Comparative Example 2 Electrode processing was performed in the same manner as in Example 1 except that the laser beam shaping system of the cylindrical lens was not used. Gaussian density distribution The average energy density was 10 j Z cn ^ (the maximum value was 2 3 j Z cm ^ and the minimum value was 3 J cm2, the ratio was 7.7 times). When the interelectrode insulating portion was observed with an optical microscope, the electrode end portion (edge portion) was not patterned in a straight line. From the above experimental results, it was found that the irradiation energy density of the laser beam and the electrical insulation between the adjacent electrodes after patterning were as follows. In order to eliminate the residual (incomplete removal) of the conductive film and ensure electrical insulation between the electrodes, it is recommended that the irradiated beam has an energy density of 8 J / cm2 or higher. Also, in order to ensure electrical insulation (resistance value of 10 Ω or more), there is an upper limit for the energy density distribution of the laser beam, which must be 16 j Z cn ^. If this value is exceeded, it will be difficult to obtain a resistance of 1 Ο Μ Ω or more with good reproducibility. The reason for this is not clear, but it is presumed that tin oxide evaporated and removed by laser beam irradiation reattaches to the glass surface, and that the glass surface is altered and deteriorated by irradiation with a strong laser beam. Furthermore, by making the cross-sectional shape of the irradiated laser beam rectangular and leveling the energy density distribution in the cross-sectional direction of the laser beam, there is no residual of the conductive film over the entire width direction of the interelectrode insulating part, and The end of the electrode can be patterned in a straight line (no jagged irregularities). According to claim 1 of the present invention, since the laser beam having a circular cross section emitted from the laser oscillator is shaped into a substantially rectangular shape by optical means, a part of the laser beam is not interrupted by shaping. Thereby, the energy of the laser beam can be efficiently irradiated onto the conductive film. In addition, since the beam shape to be checked against the conductive film is substantially rectangular, when the striped electrode is formed by sequentially shifting the laser irradiation point on the straight line, the beam does not leak in the irradiation region. It is possible to ensure the electrical insulation between them. Claim 2 is composed of an optical system in which a plurality of cylindrical lenses arranged at positions orthogonal to each other are separated by two in the axial direction of the laser beam. The optical system for shaping the cross-sectional circular beam into a rectangle can be reduced. Claim 3, the energy density distribution in the cross section direction of the laser beam irradiated on the conductive film, the maximum value of the energy was leveled so as not to exceed _twice the minimum value of the energy is irradiated in a bi chromatography beam In addition to the effect of claim 1 or 2, the occurrence of electrical insulation failure due to incomplete removal of the conductive film is suppressed, and the electrode is processed reliably. be able to. According to claim 4, the wavelength of the laser beam irradiated on the conductive film is set to 3500 nm to 200 nm, and the energy density is distributed within the range of 8 to 16 Jcm2. In addition to the effects of claims 1 to 3, it is possible to reliably ensure electrical insulation without deteriorating the surface of the glass as the substrate. According to the seventh aspect, since the optical means configured by the optical lens group for converting the cross-sectional shape of the laser beam into a substantially rectangular shape is provided between the laser oscillator and the workpiece, the laser oscillator Part of the emitted laser beam is not physically shielded. For this reason, laser energy can be used effectively, and a laser oscillator with a smaller output can be employed. According to claim 8, in addition to the effect of claim 7, the deformation of the laser beam is made into a lens group in which a plurality of cylindrical lenses are arranged in a direction orthogonal to each other, and this is arranged in the axial direction of the laser beam. Since it is composed of an optical system separated by one set, the beam can be shaped with a small component configuration. According to claim 10, since the beam scanning system having the reflection mirror and the f 0 lens is provided in the beam path between the optical means and the workpiece, the beam scanning system has the same location on the workpiece. A beam of the same shape and size can be irradiated. Industrial Applicability While irradiating a conductive film on a substrate with a laser beam emitted from a laser oscillator, the conductive film is turned into a predetermined shape electrode by relatively moving the laser beam and the substrate. In the laser processing method, the cross-sectional shape of the laser beam applied to the conductive film is shaped into a substantially rectangular shape by an optical means including an optical lens group. Since the laser beam having a circular cross section emitted from the laser oscillator is shaped into a substantially rectangular shape by optical means, a part of the laser beam is not blocked by the shaping. Thereby, the energy of the laser beam can be efficiently applied to the conductive film.

Claims

1. A conductive film on a substrate is irradiated with a laser beam emitted from a laser oscillator, and the conductive film is laser-processed into an electrode having a predetermined shape by relatively moving the laser beam and the substrate. In the method, a laser processing method characterized in that a cross-sectional shape of a laser beam applied to the conductive film is shaped into a substantially rectangular shape by an optical means including an optical lens group.

Second base

2. The optical means is composed of an optical system in which two lens groups in which a plurality of cylindrical lenses are arranged in a direction orthogonal to each other are set as a set and spaced apart in the beam axis direction of the laser beam. The laser processing method according to claim 1.

Surrounding

3. The laser processing method according to claim 1 or 2, wherein the maximum value of the energy density in the cross-sectional direction of the laser beam to be irradiated is leveled so as not to exceed twice the minimum value.

4. The wavelength of the laser beam to be irradiated is 3 5 0 η π! The laser processing method according to any one of claims 1 to 3, wherein the energy density is shaped so as to be distributed within a range of 8 to 16 J Z cms at ˜20 00 nm.

5. The laser processing method according to any one of claims 1 to 4, wherein the conductive film is a conductive film in which a tin oxide film is laminated and coated on a silicon dioxide film.

6. The laser processing method according to any one of claims 1 to 4, wherein the conductive film is a three-layer conductive film of a tin oxide film, a silicon dioxide film, and a tin oxide film.

7. In a laser processing apparatus that performs processing by irradiating a workpiece with a laser beam emitted from a laser oscillator, the cross-sectional shape of the laser beam is approximately between the laser oscillator and the workpiece. A laser processing apparatus comprising optical means including an optical lens group for shaping into a rectangle.

8. The optical means is composed of an optical system in which a lens group in which a plurality of cylindrical lenses are arranged in a direction orthogonal to each other is arranged in a pair apart from each other in the beam axis direction of the laser beam. The laser processing apparatus according to claim 7.

9. When the focal length of the cylindrical lens is f mm, the radius of curvature of the cylindrical lens is r mm, the distance between one lens group and the other lens group is L mm, and the laser beam diameter is d mm, 9. The laser processing apparatus according to claim 8, wherein the following relationship is satisfied.

f <L≤ 2 f

0.5 d <r≤ 6 d

10. The laser processing apparatus according to claim 7, wherein a laser beam staging system including a reflection mirror and an fΘ lens is provided between the optical means and the workpiece. .