JP2015199117A - Laser processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems, for example, in a processing device using line beam laser in which laser beam is transmitted by an optical fiber and generated by an optical system, a waveguide and a homogenizer are needed for making the line beam uniform, therefore results in complication of a structure and high cost, and in light focus using a high magnification object lens, length of the line beam is limited.SOLUTION: Clads of terminal end parts of optical fibers 3 of plural laser sources 2 are subjected to etching, for making intervals of cores narrow, and line beam is made uniform, by expansion of laser beam by an NA of the beam passing the optical fibers 3 and light focus of a cylindrical lens, so that long line beam is made and it is possible to radiate a wide range, in a laser processing device.

Description

  The present invention relates to a laser processing apparatus that performs processing to change the shape and material of an object using a laser by a long line beam generating optical system as a light source.

There has been proposed a laser processing apparatus that performs processing to change the shape and material of an object using a laser as a light source (see, for example, Patent Documents 1 to 16).
Many laser processing apparatuses using various lasers have been announced and put into practical use. Laser thermal processing includes metal drilling, cutting, welding, quenching, and surface processing by ablation. Recently, various laser thermal processing and non-thermal processing are also used in semiconductor processes. It has been.

  The spot of the laser beam applied to the workpiece is often a focused circular spot in the case of welding or cutting. The surface treatment process may be a line beam or a surface beam.

  For example, there is annealing of a silicon substrate. For example, there is an apparatus in which an excimer laser (XeCl) having a wavelength of 308 nanometers is used to divide a die with respect to a large area of a silicon film and anneal by irradiation or scanning of a line beam.

  There is a method in which a line beam is generated using a green laser having a wavelength of 1064 nanometers of an Nd: YAG laser, that is, a wavelength of 532 nanometers, and the beam or workpiece is moved and annealed.

  An optical transmission fiber (hereinafter referred to as an optical fiber) is aligned with a plurality of diode lasers (hereinafter referred to as laser diodes or LDs), a line beam is generated, and the laser is irradiated by moving the beam or moving the workpiece. There is a method of annealing. In this case, an apparatus has been devised that scans and processes a line beam having a limited length a plurality of times.

JP 2003-287703 A JP 2003-86505 A JP 2003-109912 A JP-A-9-129573 Japanese Patent Laid-Open No. 2006-135251 Japanese Patent Laid-Open No. 2007-088050 Japanese Patent Laid-Open No. 2007-251196 International Publication Number W2007 / 114031 JP 2008-85236 A JP 2009-16376 A JP 2009-49030 A JP 2009-206386 A JP 2009-260133 A Japanese Patent Laid-Open No. 2010-103177 Japanese Unexamined Patent Publication No. 2011-71351 JP 2013-233556 A

  There are annealing apparatuses using surface irradiation with an excimer laser or Nd: YAG laser, or line beam or spot irradiation, but there are examples in which a fly-eye lens, a waveguide or a light guide plate is used as means for making the laser beam uniform. This complicates the optical transmission method and the optical system, and the laser energy is greatly attenuated by the optical system, so that a laser light source with higher energy is required. Further, the laser oscillator itself is large and running cost is high.

  There is an example in which a plurality of LDs and a plurality of long optical fibers are used. The larger the number of optical transmission systems, the more difficult it becomes to connect to an optical system inside the machining head, for example, a waveguide.

  As an example, when a plurality of LDs are used as laser light sources, there is a device in which a driver controls the current of each LD using a laser power sensor inside an optical head. It is difficult to accurately feed back laser power to each LD.

  A line beam generating optical system using a laser light source using a plurality of LDs needs to incorporate sensors such as many fiber couplings, homogenizers, autofocus, auto power control, etc. The optical head is complicated, large, and heavy. Become. Therefore, it is not suitable for a movable head type device.

  As an example, an optical system using an LD that generates a line beam with a longitudinal direction of several hundred microns and a width of several microns as a laser light source is assumed to have a focal length of several millimeters and a focal depth of several microns. Ultra-high accuracy is required, and autofocus is also required.

  As an example, there is an apparatus for branching an optical fiber into a plurality of lines and arranging them in a line. However, it is difficult to obtain a uniform ultra-fine line beam only by general optical fiber alignment, and a linear mark remains as a result of the process.

  An apparatus using a line laser beam has been devised for zone control by welding and combining a plurality of optical fibers. By combining optical fibers, the core diameter increases and the energy per unit area of the laser decreases. Considering the coupling loss of the optical fiber, the loss increases, so the number of combine is limited.

  When trying to obtain a line beam using an array of a plurality of optical fibers, it has been particularly difficult to make the beam uniform in the longitudinal direction. The reason is that when the ratio of the core diameter of the optical fiber to the cladding diameter of the laser is large, for example, the core diameter of the optical fiber is 10 microns and the cladding diameter is 125 microns. In some cases, the core diameter is 20 microns and the cladding diameter is 400 microns. When the laser beam emitted from the core is dotted and has a large interval, when trying to make uniform using a fly-eye lens or a waveguide, the optical system becomes complicated.

  When a cylindrical high magnification objective lens having a magnification of 20 to 100 is used to generate an ultrafine line beam, the length of the laser beam is limited due to the restriction of the aperture diameter and the lens diameter.

  In the above example, a method for generating a long laser beam is not shown. At present, when processing a large area such as a roll or a sheet material, it is necessary to perform a plurality of scanning operations or step operations including overlapping using a line beam.

Means to solve the problem

  The laser processing apparatus of the present invention is a laser apparatus that processes a workpiece by irradiating the workpiece with a long laser beam. As an example of applying this laser processing apparatus to an annealing process, a case where a blue LD having a wavelength of 445 nanometers is employed as a laser light source will be described. As shown in FIG. 7 of Patent Document 16, the peak of the absorption rate curve (50) of amorphous silicon is around 450 nanometers, and the center wavelength (54) of the blue LD employed in the present invention is 445 nanometers. The center wavelength (53) of the laser has the same or close absorption characteristics. At the center wavelength (55) of the green laser, it has lower absorption characteristics than both.

  The blue LD has a wider spectrum than the excimer laser and the Nd: YAG laser, so there is less concern about interference in the optical system. It is difficult to obtain a wavelength of 445 nanometers with a laser light source other than a blue LD. Therefore, it can be said that the blue LD is the optimum laser light source for annealing the silicon-based material.

  The blue LD adopted this time uses 21 LD fiber modules manufactured by Nichia Corporation, NUB206E (engineering sample, optical output 1.3 W) with optical fibers connected. If it is used at a maximum output of 1 watt per unit, it is possible to obtain 21 W with a margin even if the loss is taken into consideration. The wavelength of the blue LD is 445 to 450 nanometers, which is optimal for annealing amorphous silicon.

  An optical fiber connected to a plurality of blue LDs, that is, a clad of a pigtail fiber, is etched to adjust a gap between the cores, and is aligned and fixed as a fiber array. In this case, since the number and length of the optical fibers are not limited, a flexible design is possible as compared with the conventional apparatus, and a reduction in size and weight can be obtained.

  Laser light emitted from the fiber array is diffused by the NA of the light passing through the fiber. If light is collected only in one direction by a first-stage convex cylindrical lens arranged along the fiber alignment axis, a circular beam becomes an elliptical beam. The elliptical beams emitted by the adjacent optical fibers at equal intervals overlap, and the laser light emitted from the entire fiber array becomes a line beam.

  The degree of overlap of the elliptical beam is adjusted by the spread angle of the laser due to the NA of the light passing through the fiber, the focal length of the fiber array and the convex cylindrical lens, and the distance between the fiber array and the lens.

  The laser beam condensed by the second-stage concave cylindrical lens is diffused close to parallel light. A third convex convex cylindrical lens is used for focusing and condensing on the workpiece.

  A blue LD power source is networked by using a plurality of commercially available multi-channel power supply devices such as PW8-3AQP (4 channels) manufactured by TEXIO or similar multi-channel power sources. It is possible to easily control a large number of blue DL currents simultaneously by USB communication or RS232C communication. It is also easy to monitor the current of each LD.

If a single blue LD or optical transmission system is damaged, it is easy to identify the damaged part by monitoring the light exit from the fiber array or leakage light from the optical fiber.

  The monitoring and feedback of the blue LD power enables the LD laser monitoring and high-speed feedback control by detecting the leakage light of the optical fiber with a sensor. Some processes do not require feedback.

  The optical head of the present invention can generate a line beam by using an etched optical fiber array and a long cylindrical lens, and does not require electrical wiring such as a sensor in the head, and is small and lightweight. Therefore, it is highly scalable as a long line beam generating head. It can also be mounted on movable heads and gantry types.

  The blue LD of optical fiber coupling has no regular replacement member and is easy to maintain. As described above, by solving the above-described example, a laser processing apparatus for annealing having a small size, low running cost, low surface roughness, and stable performance can be realized.

  As an example of the laser processing apparatus of the present invention, an example in which a plurality of LDs having a wavelength of 800 to 900 nanometers are employed as a laser light source will be described. For this reason, there are a wide variety of LDs with wavelengths in this range from low output to high output, and they can be used as heat treatment and laser excitation sources. It is possible to perform the process at a high speed as a laser light source for surface treatment of sheet, roll-shaped resin or metal, or heat treatment by a line beam by an optical fiber having an etched cladding.

  As an example of the laser processing apparatus of the present invention, an example in which a plurality of purple light LDs having a wavelength of 400 nanometers are employed as a laser light source is shown. The reason is that purple light LD has a low output of several hundred milliwatts at present, but there is a possibility of a high output of 10 watts in the future, and annealing is performed by a line beam using an optical fiber with a clad etched. It is possible to perform the process at high speed as a laser light source for surface treatment of coatings and coatings.

  As an example of the laser processing apparatus of the present invention, an example in which a plurality of ultraviolet light LDs having a wavelength of 300 nanometers are employed as a laser light source is shown. The reason for this is that ultraviolet light LD has a low output of milliwatts, but there is a possibility of higher output of watts in the future. As a laser light source for coating surface treatment, the process can be performed at high speed.

As an example of the laser processing apparatus of the present invention, an example in which a plurality of infrared optical fiber lasers having a wavelength of 1000 nanometers are employed as a laser light source is shown. Fiber lasers are of high quality, and laser light can be obtained from wattage to high output of kilowatts. As an example, it is possible to perform surface processing by heat ablation and heat treatment at high speed by a line beam by a fiber array in which a clad having a core diameter of 20 microns and a clad diameter of 400 microns is etched.

  As an example of the laser processing apparatus and annealing apparatus of the present invention, an example in which a plurality of solid-state lasers having a wavelength of 1064 nanometers and Nd: YAG lasers are employed as a laser light source will be described. For this reason, the solid-state laser can obtain a high-quality laser beam from W to KW class, and can be transmitted through an optical fiber. Also, it is possible to easily obtain CW or pulsed light. The optical fiber with the clad etched enables high-speed ablation processing and heat treatment processing using a long line beam.

Effect of the invention

  According to the laser processing apparatus and the laser annealing apparatus using the long line beam generating optical system of the present invention, compared with the conventional apparatus, the optical head is small in length from a submillimeter to a metric class practically unlimited. A line beam becomes possible, and the number of laser scans can be reduced or reduced to one, so that the processing time can be shortened. The device is also small and inexpensive.

It is a perspective view of a long line beam generating optical system, and a block diagram of a laser power source and a control system. It is the schematic of the side surface of a long line beam generation optical system. It is a longitudinal direction sectional view of an optical fiber etched uniformly. FIG. 3 is a longitudinal sectional view of an optical fiber partially etched into a taper shape. It is the schematic of the attachment side of an optical fiber. It is the schematic of the laser emission side of an optical fiber. It is a figure of the fiber array before the etching of an optical fiber (core diameter 40 microns / cladding diameter 125 microns). It is a figure of the fiber array after the etching of an optical fiber (core diameter 40 microns / cladding diameter 60 microns). It is a figure of the rectangular fiber array before the etching of an optical fiber. It is a figure of the rectangular fiber array before the etching of an optical fiber. , It is explanatory drawing of the process of etching the clad of an optical fiber uniformly. , It is explanatory drawing of the process which etches the cladding of an optical fiber in a part taper shape.

Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an implementation bear) will be described with reference to the drawings.
An embodiment (perspective view, laser light source, control system block diagram) of a long line beam generating optical system of the present invention is shown in FIG. The voltage and current set by the laser power supply unit 1 are applied to the laser light source 2 through the feeder line 24. The laser generated by the laser light source 2 is transmitted to the line beam generating optical system 26 through the optical fiber 3.

  When the optical fiber 3 is not etched, it is difficult to arrange the tips of the optical fibers 3 in parallel because the tip diameter and the original diameter of the optical fiber 3 are different. In order to solve this problem, the optical fiber 3 is three-dimensionally arranged in the line beam generating optical system 26 as shown in FIGS. In this case, the mounting position and distance are adjusted in consideration of the thickness of the buffer 28 and the jacket 27 of the optical fiber 3.

  FIG. 5 shows a three-dimensional structure of the optical fiber 3 on the fiber side. FIG. 6 shows the alignment state of the tips of the optical fibers 3. Prior to performing the etching process, the coating or jacket 27 of the optical fiber 3 and the protective film or buffer 28 of the optical fiber 3 are peeled off. The cladding at the tip of the optical fiber 3 is etched by the process shown in FIGS. 9A, 9B, 10A, and 10B. The optical fibers 5 that have been uniformly etched are aligned and fixed with a fixture and an optical adhesive to form a fiber array 6. Thereafter, the tip of the optical fiber 3 is polished and cleaned. Thereby, the space | interval of the core 18 becomes narrower than the fiber array which is not etched, and the energy per unit area increases.

  FIG. 7A shows an optical fiber array 6 having a core diameter of 40 microns and a cladding diameter of 125 microns. The optical fiber shown in this example is generally used well. However, when arrayed in an array, a special optical system is required to generate a uniform line beam when the cores 18 are spaced apart as shown in FIG.

  FIG. 7-2 shows an optical fiber array 6 etched with a core diameter of 40 microns and a cladding diameter of 125 microns to 60 microns. When FIG. 7-1 before etching of the optical fiber 3 is compared with FIG. 7-2 after etching of the optical fiber, the concentration of laser light is clearly obtained.

FIG. 8A shows a state before etching the rectangular optical fiber cladding 17-1, and FIG. Various combinations of aspect ratios of the rectangular fiber cladding 17-1 and the rectangular fiber core 18-1 are conceivable. In the case of a rectangular optical fiber, it is necessary to make the cladding diameter as small as possible while maintaining the strength.

FIG. 2 shows an outline of an optical path with a side view of the line beam generating optical system 26 for generating a long line beam. Since the laser light 10 emitted from each optical fiber of the fiber array 6 is diffused by the NA of the light, it overlaps with the laser light emitted from the adjacent optical fiber. The smaller the space between the cores 17, the larger the area.
The laser beam 10 emitted from the optical fiber is condensed by the convex cylindrical lens 7 so that the beam width in the direction perpendicular to the fiber alignment direction becomes small. The laser beam 10 in the direction perpendicular to the focused beam is made substantially parallel light by the concave cylindrical lens 8, the focus adjustment 11 is performed by the objective convex cylindrical lens 9, and the line beam 10-1 is irradiated onto the workpiece 12. .

  The workpiece 13 is moved 13 at a predetermined process parameter speed. The laser light passing through each optical fiber 3 is slightly leaked and becomes an electric signal by each fiber power sensor 14 and is converted into a signal by a fiber power signal converter 15 to be a signal 22, which is monitored by a control unit 16 and laser Feedback is made to the laser power supply unit 1 via the power setting signal line 23. Stable laser power is obtained by the feedback control. The laser power for each portion of the line beam 10-1 is measured by the power meter head 14-1, and is connected to the control unit 16 from the power meter signal converter 15-1 for display.

  As one of the methods for etching the optical fiber cladding, a chemical etching process is shown in FIGS. 9-1, 9-2, 10-1, and 10-2. The tip of the optical fiber is immersed in an etching solution 20 using hydrogen fluoride or the like, and the pulling control 21 is performed by setting the etching rate and time, and the desired diameter of the cladding 5 is obtained. FIG. 3 shows that the optical fiber 5 uniformly etched can be obtained by performing etching for a certain period of time as shown in FIGS.

  FIG. 4 shows an optical fiber 5-1 that has been gradually pulled up as shown in FIGS. 10-1 and 10-2, subjected to pull-up control 21-1, and partially etched into a tapered shape.

  The optical fiber 5-1 that has been partially etched into a tapered shape is superior in strength to the optical fiber 5 that is uniformly etched, but the etching process is complicated. As an example of a combination of both, an optical fiber having a uniform tapered portion and a part of the tip as shown in FIG. 4 can be considered. Which one is adopted is selected depending on the diameter of the optical fiber to be adopted and the structure of the optical system.

  From the above, in this embodiment, the laser processing apparatus using the long line beam generating optical system has a practically unlimited length from the submillimeter to the meter class with a small optical head as compared with the conventional apparatus. A long line beam is possible, and the number of laser scans can be reduced or reduced to one, so that the processing time can be shortened. The device is also small and inexpensive.

  The present invention is not limited to the above-described embodiment, and various other configurations can be taken without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Laser power supply unit, 2 Laser light source, 3 Optical fiber, 4 Optical fiber fixing device, 5 Uniformly etched optical fiber, 5-1 Optical fiber partially etched into taper shape, 6 Fiber array, 7 Convex cylindrical lens , 8 concave cylindrical lens, 9 convex cylindrical lens for objective, 10 laser beam, 10-1 line beam, 11 focus adjustment, 12 workpiece, 13 movement of workpiece, 14 fiber power sensor, 14-1 power meter Head, 15 Fiber power signal converter, 15-1 Power meter signal converter, 16 Control unit, 17 core, 17-1 Rectangular fiber core, 18 cladding, 18-1 Rectangular fiber cladding, 19 Etch resistant container , 20 Etching solution, 21 Pull up for a short time, 21-1 Pull up Control, 22 Fiber power sensor signal line, 22-1 Power meter signal line, 23 Laser power setting signal line, 24 Feed line, 25 Laser power supply and control system,
26 Line beam generation optics, 27 jacket, 28 buffer

Claims (4)

  A plurality of diode lasers emitting infrared light having an average output of 20 milliwatts or more, diode lasers emitting visible light, or diode lasers emitting ultraviolet light are used as light sources, and the core diameter of each optical transmission fiber is from 10 microns to 1 The ratio of the core diameter to the cladding diameter is set to a value between 1 and 1.05 or more and 1 to 2.5 or less, and the cladding of each optical transmission fiber is etched and etched. By arranging the optical transmission fibers in the three-dimensional space in parallel, the optical transmission fibers are arranged in parallel, the outgoing light surfaces of the terminal ends are aligned flush, and the intervals between the cores are narrowed and fixed. Uniformity is improved only by the spread of the laser beam due to the NA of the light passing through the optical transmission fiber without using the waveguide and the condensing property of the cylindrical lens in one direction. Laser processing apparatus using a helical lens of 0.7 millimeters condenses on the workpiece long line beam generating optics.   A plurality of fiber lasers that emit infrared light having an average output of 20 milliwatts or more, fiber lasers that emit visible light, or fiber lasers that emit ultraviolet light are used as light sources, and the core diameter of each optical transmission fiber is from 10 microns to 1 The ratio of the core diameter to the cladding diameter is set to a value between 1 and 1.05 or more and 1 to 2.5 or less, and the cladding of each optical transmission fiber is etched and etched. By arranging the optical transmission fibers in the three-dimensional space in parallel, the optical transmission fibers are arranged in parallel, the outgoing light surfaces of the terminal ends are aligned flush, and the intervals between the cores are narrowed and fixed. Uniformity is improved only by the spread of the laser beam due to the NA of the light passing through the optical transmission fiber without using the waveguide and the condensing property of the cylindrical lens in one direction. Laser processing apparatus using a long line beam generating optical system of 0.7 millimeters condenses on the workpiece by the lens.   A plurality of solid-state lasers that emit infrared light, visible light, or ultraviolet light having an average output of 20 milliwatts or more are used as light sources, and the core diameter of each optical transmission fiber is 10 microns to 1 millimeter. The ratio is set to a value between 1 and 1.05 or more and 1 to 2.5 or less, and the cladding of each optical transmission fiber termination is etched, and the optical transmission fiber of the unetched portion is arranged in three dimensions. By aligning the optical transmission fibers in parallel, aligning the outgoing light surface of the terminal end to be flush with each other and fixing the intervals between the cores, the light passing through the optical transmission fiber without using a homogenizer or a waveguide can be obtained. A length of 0.7 mm or more that improves the uniformity by only spreading the laser beam due to NA and condensing in one direction of the cylindrical lens, and condensing it on the workpiece with the cylindrical lens. Laser processing apparatus using a line beam generating optics.     4. The apparatus of claim 1, claim 2 and claim 3, wherein the core of each optical transmission fiber is rectangular, the diagonal length of each optical transmission fiber core is 10 microns to 1 millimeter, The ratio of the angular length and the cladding diameter is set to a value between 1 and 1.05 and 1 to 2.5 and the cladding of each optical transmission fiber is etched, and the optical transmission fiber in the unetched portion By arranging the optical transmission fibers in parallel, the optical transmission fibers are arranged in parallel, the outgoing light surface of the terminal end is aligned and the intervals between the cores are narrowed and fixed, and the light is transmitted without using a homogenizer or a waveguide. Longer than 0.7mm that improves the uniformity only by the spread of the laser beam due to the NA of the light passing through the transmission fiber and the condensing property of the cylindrical lens in one direction, and condenses it on the workpiece with the cylindrical lens Laser processing device using the in-beam generating optical system.

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