JP2012125788A - Laser processing method and laser processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser processing method by which a substrate without particle contamination and patterned by high-quality thin film can be attained at high yield, and to provide a laser processor.SOLUTION: The laser processor includes: a conveyance means for conveying a substrate 1 along a predetermined route; a liquid tank 20 that is arranged so that the substrate 1 may be immersed in a liquid 21 on the midway of the conveyance route for the substrate and be taken out therefrom; a laser beam irradiation device 30 that directs a laser beam to a thin film through the liquid 21 in the liquid tank 20 to pattern the thin film into a predetermined shape; and a liquid removing device 40 for removing a liquid adhered to the surface of the substrate taken out from the liquid tank 20. The laser processor is used to process the substrate having a thin film with a laser.

Description

  The present invention relates to a laser processing method and a laser processing apparatus for patterning by irradiating a laser beam onto a substrate on which a thin film is formed.

  One of the processing techniques is laser processing. Laser processing is widely used in various fields such as a solar cell manufacturing process because of its excellent processing accuracy.

  However, when laser processing is performed by irradiating the workpiece with laser light, processing residues of the workpiece are scattered and easily reattached to the surface of the workpiece.

  For this reason, a dust collection mechanism for collecting particles is provided around the laser processing unit to prevent scattering of processing residues, but since the dust collection mechanism is exhausted, a large capacity exhaust A blower was required, and there were problems such as increased equipment size and increased power consumption. In addition, when a large amount of exhaust air is exhausted from the dust collection mechanism, the temperature and humidity of the production line fluctuate, so it is necessary to reinforce the air conditioning equipment.

  Further, Patent Documents 1 and 2 disclose that by disposing a workpiece in a liquid and performing laser processing, scattering of processing residues can be prevented and particle contamination can be suppressed.

JP-A-6-142971 JP 2001-219290 A

  However, the cited documents 1 and 2 do not disclose any processing after the workpiece after laser processing is taken out from the liquid. If the droplets are attached and transported to the next process and incorporated into a final product or the like, the quality of the final product may vary or cause failure. In particular, in a substrate on which a semiconductor thin film such as a solar cell substrate is formed, the impurity concentration of the thin film varies depending on the droplets, and the performance of the final product incorporating the substrate is likely to vary.

  Therefore, an object of the present invention is to provide a laser processing method and a laser processing apparatus capable of obtaining a substrate patterned with a thin film of good quality without particle contamination with a high yield.

In achieving the above object, the laser processing method of the present invention is a laser processing method for removing a part of the thin film by irradiating the substrate on which the thin film is formed with laser light.
A laser processing step of immersing the substrate in a liquid in a liquid tank in the middle of transportation, and irradiating the thin film with laser light through the liquid to pattern the thin film into a predetermined shape;
A liquid removal step of removing the liquid from the liquid tank and removing the liquid adhering to the surface of the substrate.

  According to the laser processing method of the present invention, since the substrate is immersed in the liquid in the liquid tank in the middle of conveyance and patterned by irradiating the thin film on the surface of the substrate with the laser beam through the liquid, a processing residue is generated during laser processing. However, it does not scatter around and flows by the liquid around the substrate. For this reason, reattachment of the processing residue to the substrate surface can be prevented, and particle contamination can be suppressed. In addition, since laser processing is performed in a liquid, thermal damage to the substrate can be reduced. Then, after laser processing of the substrate in this way, the liquid adhering to the substrate surface taken out from the liquid tank is immediately removed, so fluctuations in the impurity concentration of the thin film due to droplets can be suppressed, and variations in the quality of the thin film can be suppressed. Can be suppressed. For this reason, it is possible to manufacture a substrate patterned with a thin film of good quality without particle contamination with a high yield.

  In the laser processing method of the present invention, the substrate is a flexible substrate, and the flexible substrate is pulled out from the unwinding device on which the flexible substrate is wound, and immersed in the liquid in the liquid tank. The laser processing step is performed while the flexible substrate is conveyed by a guide roll in the liquid, and then the flexible substrate is taken out of the liquid tank, the liquid removing step is performed, and the film is wound by a winding device. It is preferable. According to this aspect, laser processing can be performed by a roll-to-roll method while preventing particle contamination and contamination of the substrate by droplets.

  The laser processing method of the present invention is preferably used by circulating the liquid in the liquid tank and removing processing residues in the liquid in the course of the circulation path. According to this aspect, since the liquid in the liquid tank is circulated and used, the operating cost required for laser processing can be further reduced.

  In the laser processing method of the present invention, the processing surface of the substrate is immersed in the liquid in the liquid tank so that the processing surface of the substrate is directed downward in the vertical direction or in the horizontal direction. It is preferable to irradiate the thin film through a liquid.

  In the laser processing method of the present invention, it is preferable to perform the laser processing step while causing the liquid to flow in a direction opposite to the transport direction of the substrate. According to this aspect, the processing residue generated at the time of laser processing can be efficiently washed away with the liquid in the liquid tank, so that particle contamination can be efficiently prevented.

  In the laser processing method of the present invention, it is preferable to perform the laser processing step while flowing the liquid in a direction opposite to the moving direction of the irradiation position of the laser light. According to this aspect, the processing residue generated at the time of laser processing can be efficiently washed away with the liquid in the liquid tank, so that particle contamination can be efficiently prevented.

  In the laser processing method of the present invention, it is preferable that the liquid removing step is performed by at least one means of removing droplets by air blow, wiping with a water absorbing roll, and drying in a drying furnace.

Further, the laser processing apparatus of the present invention is a laser processing apparatus that removes a part of the thin film by irradiating the substrate on which the thin film is formed with laser light.
Transport means for transporting the substrate along a predetermined path;
A liquid tank disposed so that the substrate is immersed in a liquid and taken out in the middle of the transport path of the substrate;
A laser beam irradiation device configured to pattern the thin film into a predetermined shape by irradiating the thin film with a laser beam through the liquid in the liquid tank;
And a liquid removing device that removes the liquid adhering to the surface taken out from the liquid tank.

  According to the laser processing apparatus of the present invention, since the substrate is immersed in the liquid in the liquid tank while being transported, and laser light is irradiated onto the thin film on the surface of the substrate through the liquid and patterned, processing residues are generated during laser processing. However, it does not scatter around and is washed away by the liquid around the substrate, and reattachment to the substrate is suppressed. Then, the substrate laser-processed in this manner is taken out from the liquid tank, and the liquid adhering to the substrate surface is removed by the liquid removing device. For this reason, it is possible to manufacture a substrate patterned with a thin film of good quality without particle contamination with a high yield.

  In the laser processing apparatus of the present invention, the substrate is a flexible substrate, and a substrate unwinding device on which the flexible substrate is wound is disposed in the front stage of the liquid tank, and is disposed in the rear stage of the liquid removing device. It is preferable that a substrate winding device for winding the substrate from which the liquid has been removed is disposed, and the liquid tank is disposed with a guide roll for transporting the substrate. According to this aspect, the substrate can be laser processed by a roll-to-roll method.

  The laser processing apparatus of the present invention includes a liquid circulation means for taking out the liquid in the liquid tank and flowing it along a predetermined path, and then returning it to the liquid tank, and processing residues in the liquid in the middle of the circulation path. It is preferable to provide a processing residue removing device to be removed. According to this aspect, since the liquid in the liquid tank is circulated and used, the operating cost required for laser processing can be further reduced.

  The laser processing apparatus of the present invention is configured such that the transport unit is immersed in the liquid in the liquid tank with the processing surface of the substrate facing downward in the vertical direction or laterally in the horizontal direction, and the laser beam irradiation apparatus It is preferable that the thin film is irradiated with the laser beam from below in the vertical direction or from the side in the horizontal direction.

  The laser processing apparatus of the present invention preferably includes a flow means for causing the liquid to flow in a direction opposite to the substrate transport direction in the liquid tank.

  The laser processing apparatus of the present invention preferably includes a flow means for causing the liquid to flow in the liquid tank in a direction opposite to the moving direction of the laser light irradiation position. According to this aspect, the processing residue generated at the time of laser processing can be efficiently washed away with the liquid in the liquid tank, so that particle contamination can be efficiently prevented.

  In the laser processing apparatus of the present invention, it is preferable that the liquid removing apparatus has at least one means of an air blow, a water absorption roll, and a drying furnace.

  According to the present invention, a substrate patterned with a thin film having no particle contamination and good quality can be obtained with a high yield.

It is the schematic of 1st Embodiment of the laser processing apparatus of this invention. It is the schematic of 2nd Embodiment of the laser processing apparatus of this invention.

  The “substrate having a thin film formed on its surface (hereinafter referred to as a thin film forming substrate)” used in the present invention is not particularly limited and can be preferably used in any form. For example, from materials such as polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN), polyarylate (PAR), polyamideimide (PAI), polybenzimidazole (PBI), polysulfone (PSF), etc. An example is a solar cell forming substrate in which a thin film such as a semiconductor is formed on the surface of a flexible substrate, a glass substrate, a stainless steel substrate, or the like. As the type of substrate, a flexible substrate is preferable. By using a flexible substrate, laser processing by a roll-to-roll method is possible, and laser processing can be performed with high productivity. Hereinafter, the case where a flexible substrate is used as a substrate material will be described as an example.

(First embodiment)
A first embodiment of the laser processing apparatus of the present invention will be described with reference to FIG.

  As shown in FIG. 1, in the laser processing apparatus, a liquid tank 20 is disposed at a subsequent stage (downstream in the traveling direction of the thin film forming substrate 1) on which the thin film forming substrate 1 is wound. The thin film forming substrate 1 drawn out from the unwinding roll 10 is guided by the guide roll 11 and conveyed to the liquid tank 20.

  The liquid tank 20 is filled with a liquid 21 that has a low laser beam absorptivity, high volatility, and does not damage the thin film stack or substrate of the thin film forming substrate 1 such as corrosion, elution, or peeling. The liquid 21 is preferably water.

  A plurality of (two in this embodiment) transport rolls 22 are disposed above the liquid level of the liquid 21 in the liquid tank 20, and the thin film forming substrate 1 immersed in the liquid 21 in the liquid tank 20 is transported by the transport roll 22. , 22 are transported in a tensioned state. In this embodiment, the laser processing surface of the thin film forming substrate 1 is immersed and transported in the liquid 21 so as to be vertically downward.

  Below the liquid tank 20, a circulation path L1 is connected to the upstream side in the traveling direction of the thin film forming substrate 1 and the downstream side in the traveling direction, and the liquid 21 in the liquid tank 20 is extracted from the upstream side and returned to the downstream side. Is arranged. A processing residue removing device 23 and a liquid feed pump P1 are arranged in the circulation path L1. By operating the liquid feed pump P1, the processing residue contained in the liquid 21 is collected by the processing residue removing device 23, while the liquid 21 in the liquid tank 20 is in the direction opposite to the transport direction of the thin film forming substrate 1 (FIG. 1). In the direction of the arrow). The processing residue removal device 23 is not particularly limited as long as it can recover the processing residue contained in the liquid, and can be appropriately selected according to the type of processing residue. Examples thereof include a filtering device such as a filter, a device that collects and precipitates with a chemical, a device that draws a processing residue by applying a voltage between the electrodes and collects it, and a centrifugal separator. In the case where the processing residue has an electric charge, a device that pulls the processing residue to the electrode and collects it by applying a voltage between the electrodes is preferably used. Further, when the processing residue is heavy, a centrifugal separator or the like is preferably used.

  The laser beam irradiation device 30 is mainly composed of a laser oscillator 31, a condenser lens or mirror 32, and an XY stage 33, and is perpendicular to the laser processing surface of the thin film forming substrate 1 in the liquid 21. It arrange | positions so that a laser beam can be irradiated from the downward direction. Note that the irradiation direction of the laser light is not necessarily along the vertical direction. Examples of the laser light include a YAG laser, a second harmonic YAG laser, a third harmonic YAG laser, and an argon ion laser, and are not particularly limited.

  A liquid removing device 40 is disposed downstream of the liquid tank 20 (downstream of the thin film forming substrate 1 in the traveling direction). Although there is no limitation in particular as the liquid removal apparatus 40, a water absorption roll, an air blow apparatus, a drying furnace etc. are mentioned, These 1 type (s) or 2 or more types can be used. Examples of the water absorbing roll include those made of polyester, polyurethane, polyvinyl alcohol, polyvinyl chloride, or the like. Examples of the drying furnace include an electric drying furnace and a hot air drying furnace.

  In this embodiment, the liquid removing device 40 includes an air blow device 41, a water absorption roll 42, and a drying furnace 43. From the upstream side in the transport direction, the air blow device 41, the water absorption roll 42, and the drying furnace 43 are sequentially provided. Has been placed. The air blowing device 41 is provided with nozzles so that gas can be blown onto both surfaces of the thin film forming substrate 1. Further, the water absorbing roll 42 allows the liquid adhering to the surface of the thin film forming substrate 1 to be wiped off by the water absorbing roll 42 by allowing the thin film forming substrate 1 to pass through the gap between the backup roll 45 and the water absorbing roll 42. Has been.

  At the subsequent stage of the liquid removing device 40 (downstream in the direction of travel of the thin film forming substrate 1), the slow current forming device 51, the guide roll 52, and the winding roll 50 are arranged in this order. Is taken up by the take-up roll 50.

  Next, a laser processing method of the present invention using this laser processing apparatus will be described.

  First, the thin film forming substrate 1 is pulled out from the unwinding roll 10 at a constant speed and guided to the liquid tank 20, and the thin film forming substrate 1 is immersed in the liquid 21. Note that it is sufficient that at least the laser processed surface of the thin film forming substrate 1 is immersed in the liquid 21, and the entire thin film forming substrate 1 may not be immersed in the liquid.

  Next, the thin film forming substrate 1 immersed in the liquid 21 is transported in the liquid in a state where tension is applied by the transport roll 22. Then, the laser processing surface of the thin film forming substrate 1 is irradiated with laser light from the laser light irradiation device 30 during the conveyance, and the thin film forming substrate 1 is laser processed. The laser beam is scanned in the same direction as the flow direction of the liquid 21 in the liquid tank 20 in the direction opposite to the transport direction of the thin film forming substrate 1, and the laser beam is processed by the processing residue existing in the liquid. It is preferable for the reason that processing quality deterioration due to absorption is avoided. Without such a configuration, if the laser processing residue subsequently floats in the laser processing region, the floating processing residue hinders laser transmission and processing at a predetermined depth is prevented. This is not preferable because the quality of laser processing that cannot be performed or floating matter adheres to the thin film forming substrate by the laser and the cut portion becomes conductive.

  When laser processing is performed by irradiating the thin film forming substrate 1 with laser light, processing residues such as scraps such as the substrate and the thin film are generated, but the liquid 21 is fed in a direction opposite to the transport direction of the thin film forming substrate 1 by the liquid feed pump P1 ( Since the fluid flows in the direction of the arrow in FIG. 1, the generated processing residue is washed away by the liquid 21 and is washed away from the periphery of the thin film forming substrate 1. Then, the liquid 21 containing the processing residue is led to the processing residue removing device 23 through the circulation path L1, and after the processing residue is removed, it returns to the liquid tank 20. For this reason, there is always a liquid 21 with little foreign matter such as processing residue around the thin film forming substrate 1. Therefore, the processing residue hardly adheres to the surface of the thin film forming substrate 1 and particle contamination hardly occurs. In addition, since laser processing is performed in a liquid, the thin film is hardly overheated and the thin film is not easily damaged by heat.

  Here, when the thin film forming substrate 1 is irradiated with laser light in the liquid 21, the thin film forming substrate 1 may flutter due to water flow, and distortion may occur. The following methods (1) and (2) can be cited as countermeasures for reducing the flutter of the thin film forming substrate 1 due to water flow.

(1) The distance between the centers of adjacent transport rolls 22 is narrowed, and the thin film forming substrate 1 is pulled with a tension that does not lose the flow of the liquid 21. The center-to-center distance between the adjacent transport rolls 22 and 22 is not particularly limited because it varies depending on the material and film thickness of the thin film forming substrate 1.
(2) Laser processing of the thin film forming substrate 1 is performed on the transport roll 22. If the thin film forming substrate 1 is in contact with the transport roll 22, flapping of the thin film forming substrate 1 in the liquid 21 can be reduced. Then, an actuator is installed in the laser light irradiation device 30 and the distance between the optical head of the laser light irradiation device 30 and the transport roll 22 is kept constant, and the focal distance is controlled to be constant.

  If the thin film forming substrate 1 is immersed in a liquid for a long time, the thin film or the substrate may be adversely affected. For example, when the thin film forming substrate 1 is a solar cell substrate, the impurity concentration of the thin film fluctuates, which causes variations in battery characteristics. For this reason, it is preferable that the time for immersing the thin film forming substrate 1 in the liquid 21 is short.

  In this way, after the laser processing of the thin film forming substrate 1 is performed in the liquid 21, the thin film forming substrate 1 subjected to the laser processing is taken out from the liquid tank 20 and guided to the liquid removing device 40 and attached to the thin film forming substrate 1. The removed liquid is removed.

  In the liquid removing device 40, a gas (air, nitrogen gas, etc.) is blown from the air blowing device 41 to the thin film forming substrate 1 to remove droplets attached to the surface. Next, the thin film forming substrate 1 is passed between the backup roll 45 and the water absorbing roll 42, and the liquid adhering to the surface of the thin film forming substrate 1 is wiped with the water absorbing roll 42. And it introduce | transduces into the drying furnace 43 and performs a drying process. If the drying temperature in the drying furnace 43 exceeds the temperature at which the melting point of the flexible substrate or the chemical characteristics / structure of the formed thin film changes, the thin film formed on the substrate surface may be thermally damaged.

  As for the replacement time of the water absorption roll 42 and the drying conditions in the drying furnace, a moisture meter or the like is provided at the subsequent stage of the liquid removing device 40 to detect the water content of the thin film forming substrate 1 in-line, and according to the water content of the thin film forming substrate 1 May be adjusted.

  In this way, after the liquid removal apparatus 40 performs the removal process of the liquid adhering to the thin film forming substrate 1, the liquid removal apparatus 40 performs the slow current treatment with the slow current device 51 and winds it on the winding roll 50.

  In this embodiment, the processed surface of the thin film forming substrate 1 is immersed in the liquid 21 in the liquid tank 20 with the processing surface of the thin film forming substrate 1 facing downward in the vertical direction, and the processing surface of the thin film forming substrate 1 is irradiated from below in the vertical direction. However, the processing surface of the thin film forming substrate 1 is immersed in the liquid 21 in the liquid tank 20 with the processing surface of the thin film forming substrate 1 facing the horizontal direction, and the processing surface of the thin film forming substrate 1 is irradiated from the side of the horizontal direction. Also good. In this case, the irradiation direction of the laser light does not necessarily have to be along the horizontal direction.

(Second Embodiment)
A second embodiment of the laser processing apparatus of the present invention will be described with reference to FIG. It should be noted that substantially the same parts as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  In this embodiment, one transport roll 22a is disposed above the liquid level of the liquid 21 in the liquid tank 20a. A part of the transport roll 22a is immersed in the liquid 21, and laser processing is performed by irradiating a processing laser to a portion where the thin film forming substrate 1 is in close contact with the transport roll 22a. The liquid tank 20a has a cross-sectional shape that follows the roll surface of the transport roll 22a, and the cross-sectional area of the liquid flowing through the liquid tank 20a is constant.

  According to the laser processing apparatus of this embodiment, the back surface side of the thin film forming substrate 1 is immersed in the liquid 21 in a state of being in close contact with the transport roll 22a, so that an unnecessary surface for laser processing is not exposed to the liquid. The liquid removal process in the liquid removal apparatus 40 can be performed in a shorter time.

  Further, since the laser processing is performed in a state where the thin film forming substrate 1 is in close contact with the transport roll 22a, the fluttering of the thin film forming substrate 1 in the liquid 21 can be suppressed and laser processing can be performed with high accuracy.

1: Thin film forming substrate 10: Unwinding roll 11, 52: Guide roll 20, 20a: Liquid tank 21: Liquid 22, 22a: Transport roll 23: Processing residue removing device 30: Laser beam irradiation device 31: Laser oscillator 32: Condensing mirror 33: XY stage 40: Liquid removal device 41: Air blow device 42: Water absorption roll 43: Drying furnace 45: Backup roll 50: Winding roll 51: Slow electric device L1: Circulation path P1: Liquid feed pump

Claims (14)

In the laser processing method of removing a part of the thin film by irradiating the substrate on which the thin film is formed with laser light,
A laser processing step of immersing the substrate in a liquid in a liquid tank in the middle of transportation, and irradiating the thin film with laser light through the liquid to pattern the thin film into a predetermined shape;
A liquid removing step of removing the substrate from the liquid tank and removing the liquid adhering to the surface of the substrate.   The substrate is a flexible substrate, and the flexible substrate is pulled out from the unwinding device on which the flexible substrate is wound, immersed in the liquid in the liquid tank, and the flexible in the liquid 2. The laser according to claim 1, wherein the laser processing step is performed while the substrate is conveyed by a guide roll, and then the flexible substrate is taken out of the liquid tank, the liquid removal step is performed, and the substrate is wound by a winding device. Processing method.   The laser processing method according to claim 1 or 2, wherein the liquid in the liquid tank is used by being circulated, and processing residues in the liquid are removed in the middle of the circulation path.   The processing surface of the substrate is immersed in the liquid in the liquid tank so that the processing surface of the substrate is directed downward in the vertical direction or in the horizontal direction, and the thin film is irradiated with the laser light from the lower side in the vertical direction or from the horizontal direction through the liquid. Item 4. The laser processing method according to any one of Items 1 to 3.   The laser processing method according to claim 1, wherein the laser processing step is performed while flowing the liquid in a direction opposite to the transport direction of the substrate.   The laser processing method according to claim 1, wherein the laser processing step is performed while flowing the liquid in a direction opposite to a moving direction of the irradiation position of the laser light.   The laser processing method according to any one of claims 1 to 6, wherein the liquid removing step is performed by at least one means of removing droplets by air blow, wiping with a water absorbing roll, and drying in a drying furnace. In a laser processing apparatus for removing a part of the thin film by irradiating the substrate on which the thin film is formed with a laser beam,
Transport means for transporting the substrate along a predetermined path;
A liquid tank disposed so that the substrate is immersed in a liquid and taken out in the middle of the transport path of the substrate;
A laser beam irradiation device configured to pattern the thin film into a predetermined shape by irradiating the thin film with a laser beam through the liquid in the liquid tank;
A laser processing apparatus, comprising: a liquid removing device that removes the liquid attached to the surface taken out of the liquid tank. The substrate is a flexible substrate;
A substrate unwinding device in which a flexible substrate is wound is disposed in the previous stage of the liquid tank,
A substrate take-up device that winds up the substrate from which the liquid has been removed is disposed after the liquid removing device.
The laser processing apparatus according to claim 8, wherein a guide roll for conveying the substrate is disposed in the liquid tank.   A liquid circulating means for taking out the liquid in the liquid tank and causing it to flow along a predetermined path and then returning it to the liquid tank, and a processing residue removing device for removing processing residues in the liquid in the middle of the circulating path The laser processing apparatus of Claim 8 or 9 provided. The transport means is configured to immerse the processing surface of the substrate in the liquid in the liquid tank with the processing surface of the substrate facing vertically downward or horizontally laterally, and the laser light irradiation device causes the laser light to be vertically downward Or the laser processing apparatus as described in any one of Claims 8-10 comprised so that the said thin film may be irradiated from a horizontal direction side.
  The laser processing apparatus according to any one of claims 8 to 11, further comprising a flow unit configured to flow the liquid in the liquid tank in a direction opposite to a conveyance direction of the substrate.   The laser processing apparatus according to any one of claims 8 to 12, further comprising a flow unit configured to flow the liquid in the liquid tank in a direction opposite to a moving direction of the irradiation position of the laser light.   The laser processing apparatus according to any one of claims 8 to 13, wherein the liquid removing apparatus includes at least one means of an air blow, a water absorption roll, and a drying furnace.