JP2013018036A - Laser processing method and laser processing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent damage on a transparent conductive film or the like by carrying out processing of cutting and removing a back surface electrode film and a photoelectric conversion layer without trouble in a manufacturing process of a solar cell or an electroluminescence device.SOLUTION: A first irradiation process, in which a laser beam 43 irradiates the back surface electrode film 3 on an uppermost layer and at least the back surface electrode film 3 is cut, and a second irradiation process, in which a laser beam 44 irradiates a periphery of a part which is irradiated with the laser beam 43 in the first irradiation process and the photoelectric conversion layer 2 remaining below the back surface electrode film 3 is cut, are separately carried out. The laser beam 43 applied in the first irradiation process and the laser beam 44 applied in the second irradiation process are preferably different from each other in wavelength, output, pulse width, and beam profile.

Description

  The present invention relates to a laser processing method and a laser processing machine for performing a process of removing a plurality of stacked layers of different materials.

  For example, a solar cell currently in practical use is configured by forming a laminated film, that is, a first electrode film, a power generation layer (photoelectric conversion layer, light absorption layer), and a second electrode film on a substrate. The In the case of an organic solar cell using an organic compound for the power generation layer, a transparent conductive film, an organic semiconductor film, and a back electrode film (typically a metal film) are stacked in this order on the substrate.

  Such a laminated structure is the same in electroluminescence devices such as displays and surface-emitting illumination (including organic light-emitting diodes (OLED) and light-emitting polymers (LEP)). That is, a transparent conductive film, a light emitting layer (photoelectric conversion layer), and a back electrode film are stacked on the substrate in this order.

  A general procedure for manufacturing a thin film solar cell will be outlined with reference to the following patent documents. First, a transparent conductive film as a first electrode film is formed on a transparent substrate, and a separation groove for dividing the transparent conductive film into cell units is formed (P1 processing). Subsequently, a photoelectric conversion layer is formed on the transparent conductive film, and a separation groove is formed in the photoelectric conversion layer (P2 processing). The constituent material of the photoelectric conversion layer enters the separation groove previously formed in the transparent conductive film. Further, a back electrode film as a second electrode film is formed on the photoelectric conversion layer, and the back electrode film is removed together with the photoelectric conversion layer to form a separation groove (P3 processing). The constituent material of the back electrode film enters the separation groove previously formed in the photoelectric conversion layer. Through the above, a structure in which a plurality of cells functioning as photovoltaic elements are connected in series is completed.

  In P3 processing in the manufacture of silicon-based solar cells, a laser electrode having a wavelength that can be absorbed by a semiconductor film that is a photoelectric conversion layer is transmitted from the substrate side through the substrate and irradiated to the semiconductor film. Of course, the semiconductor film can be blown away.

  On the other hand, in the production of organic solar cells, organic electroluminescent devices, etc., it is difficult to perform P3 processing using the above-described method. Therefore, it is necessary to irradiate the laser beam from the back electrode film side to cut and remove the back electrode film and the photoelectric conversion layer.

  However, the metal film serving as the back electrode film has a higher processing threshold than the other layers. In other words, the metal film cannot be sufficiently removed unless laser light having stronger energy is irradiated. In the manufacture of organic solar cells and organic electroluminescence devices, when a metal film and a photoelectric conversion layer are removed all at once by irradiating a laser beam with strong energy onto the metal film, not only the photoelectric conversion layer but also the layer below it. There is a tendency that even a transparent conductive film layer is damaged and the performance of the product is deteriorated. Therefore, in the past, many thought that it was unrealistic to perform P3 processing using a laser processing machine.

Japanese Patent No. 4563491

  The present invention is intended to solve the problem in the case where the laser processing threshold of the uppermost layer is high when performing processing for removing a plurality of layers of different layers from each other.

  The present invention is a laser processing method for performing a process of removing a plurality of laminated layers made of different materials, and irradiating a laser beam toward the uppermost layer of the plurality of layers, at least the most. A first irradiation step for removing the upper layer, and a second irradiation for removing the layer remaining below the uppermost layer by irradiating the laser beam in the vicinity of the portion irradiated with the laser beam in the first irradiation step. The laser processing method including the process was carried out. In short, the laser light is intentionally divided into a plurality of times and a plurality of layers are removed.

  In the laser beam irradiated in the first irradiation step and the laser beam irradiated in the second irradiation step, the wavelength, output, pulse width, repetition frequency, beam profile (projection shape of the laser beam, and / Or change at least one of energy density distribution in the projected shape) or processing speed (irradiation time of the laser beam to the processing site or relative movement speed of the processing nozzle that emits the laser light with respect to the processing object). be able to.

  The uppermost layer is, for example, a metal film. As already described, the metal film has a high laser processing threshold.

  If the object to be processed is a solar cell or an electroluminescence device, the layer existing below the uppermost electrode film is a photoelectric conversion layer.

  The present invention is particularly suitable for the production of organic solar cells or organic electroluminescent devices. That is, if the method of the present invention is adopted, P3 processing for removing both the back electrode film (metal film) which is the uppermost layer and the organic thin film semiconductor or the light emitting layer existing below the back electrode film can be easily performed.

  According to the present invention, it is possible to solve the problem in the case where the laser processing threshold value of the uppermost layer is high when performing the processing for removing the plurality of stacked layers of different materials.

The figure which shows the procedure of the manufacturing method of the thin film solar cell of one Embodiment of this invention. The figure which shows the procedure of the manufacturing method of the thin film solar cell of the embodiment. The figure which shows the procedure of the manufacturing method of the thin film solar cell of the embodiment. The figure which shows the procedure of the manufacturing method of the thin film solar cell of the embodiment. The figure which shows the procedure of the manufacturing method of the thin film solar cell of the embodiment. The figure which shows the procedure of the manufacturing method of the thin film solar cell of the embodiment. The figure which shows the procedure of the manufacturing method of the thin film solar cell of the embodiment. The figure which shows the structure of the battery completed with the manufacturing method of the thin film solar cell of the embodiment. The figure which shows the laser beam irradiation means of the laser processing machine for enforcing the manufacturing method of the thin film solar cell of the embodiment. The figure which shows the laser beam irradiation means of the laser processing machine for enforcing the manufacturing method of the thin film solar cell of the embodiment. The perspective view which shows the schematic structure of the whole laser beam machine for enforcing the manufacturing method of the thin film solar cell of the embodiment.

An embodiment of the present invention will be described with reference to the drawings. The laser processing method of this embodiment is intended for the production of organic solar cells or organic electroluminescence devices. The manufacturing method of the solar cell of this embodiment shown in FIGS. 1 to 7 includes the following steps.
(A) Film formation of the first electrode film (b) Separation groove formation of the first electrode film (P1 processing)
(C) Film formation of photoelectric conversion layer (d) Separation groove formation of photoelectric conversion layer (P2 processing)
(E) Formation of second electrode film (f) Separation groove formation of photoelectric conversion layer and second electrode film (P3 processing)
As shown in FIG. 1, in the film forming step (a), a transparent conductive film 1 as a first electrode film is deposited on a transparent substrate base material 0 by a CVD method or the like. The transparent conductive film is, for example, an ITO film or a TCO film such as ZnO. However, if a glass substrate on which the transparent conductive film 1 has been formed in advance for production of solar cells or the like can be obtained, the film forming step (a) can be omitted.

  As shown in FIG. 2, in the laser processing step (b), a plurality of separation grooves 11 that divide the transparent conductive film 1 into cells are cut and formed by irradiating a laser beam 41. The laser light 41 may be transmitted through the substrate 0 from the substrate 0 side as shown on the left side in the drawing and irradiate the transparent conductive film 1, or the substrate 0 from the film surface side as shown on the right side in the drawing. The transparent conductive film 1 may be directly irradiated without transmitting the light.

  The laser light 41 is, for example, a near infrared laser with a wavelength of 1064 nm, a green laser with a wavelength of 532 nm, or an ultraviolet laser with a wavelength of 355 nm. The pulse width of the laser beam 41 is not particularly limited, and may be a picosecond laser or a nanosecond laser.

  As shown in FIG. 3, in the film forming step (c), the photoelectric conversion layer 2 is formed on the transparent conductive film 1 by a vapor deposition method, a CVD method, a coating method, or the like. At this time, the constituent material of the photoelectric conversion layer 2 enters the separation groove 11 previously formed in the transparent conductive film 1. When the product to be manufactured is an organic solar cell or an organic electroluminescence device, the photoelectric conversion layer 2 includes an organic compound semiconductor or a light emitting diode element.

  As shown in FIG. 4, in the laser processing step (d), a plurality of separation grooves 21 that divide the photoelectric conversion layer 2 into cells are cut and formed by irradiating the laser beam 42. The laser light 42 is transmitted through the substrate 0 from the substrate 0 side and applied to the transparent conductive film 1. The laser light 41 may be applied to the photoelectric conversion layer 2 through the substrate 0 and the transparent conductive film 1 from the substrate 0 side as shown on the left side of the figure, or as shown on the right side of the figure. The photoelectric conversion layer 2 may be directly irradiated without passing through the substrate 0 from the surface side.

  The laser beam 42 may be the same as the laser beam 41 in the laser processing step (b).

  As shown in FIG. 5, in the film forming step (e), an opaque back electrode film 3 as a second electrode film is deposited on the photoelectric conversion layer 2 by a sputtering method or the like. At this time, the constituent material of the back electrode film 3 enters the separation groove 21 previously formed in the photoelectric conversion layer 2. The back electrode film 3 is made of, for example, Mo, Ag, Al, Cu, or other metal.

  Thus, as shown in FIGS. 6 and 7, in the laser processing step (f), a plurality of separations that irradiate the laser beams 43 and 44 and divide the back electrode film 3 and the photoelectric conversion layer 2 into cell units. The groove 31 is formed by cutting. In the present embodiment, when the separation groove 31 is formed, the laminated films 3 and 2 are irradiated with the laser beams 43 and 44 in a plurality of times. In the illustrated example, the laser beams 43 and 44 are irradiated twice.

  In the first irradiation step shown in FIG. 6 in the laser processing step (f), the laser beam 43 is not transmitted through the substrate 0, but from the film surface side on which the laminated films 3, 2, 1 are formed. The back electrode film 3 is irradiated to cut off at least the back electrode film 3 corresponding to the uppermost layer. In the first irradiation step, only the back electrode film 3 may be removed, or not only the back electrode film 3 but also the photoelectric conversion layer 2 located therebelow may be partially removed as illustrated. Good.

  In the second irradiation step shown in FIG. 7, the laser beam 44 is irradiated with the laser beam 43 in the first irradiation step from the film surface side on which the laminated films 3, 2, and 1 are also formed. Irradiation is performed in the vicinity of the portion, and the photoelectric conversion layer 2 remaining below the back electrode film 3 is cut and removed.

  The laser beam 44 irradiated in the first irradiation step and the laser beam 43 irradiated in the second irradiation step have at least one of the wavelength, output, pulse width, repetition frequency, beam profile, or processing speed. Make it different.

  For example, the laser beam 43 reliably removes the back electrode film 3 as a laser having a wavelength of 532 nm, and the laser beam 44 damages the transparent conductive film 1 and the substrate base material 0 while removing the photoelectric conversion layer 2 as a laser having a wavelength of 1064 nm. Avoid giving.

  Alternatively, the output or energy density of the laser beam 43 is set large enough to remove the back electrode film 3, while the output or energy density of the laser beam 44 is set smaller than the laser beam 43. Also good. When the outputs of the lasers 43 and 44 are changed between the first irradiation process and the second irradiation process, the wavelengths of the lasers 43 and 44 may be the same. It is also conceivable to change the pulse width between the laser beam 43 and the laser beam 44.

  Through the above steps (a) to (f), a path for electric charge is completed as shown by an arrow in FIG. 8, and a structure of a solar cell or an electroluminescence device in which a plurality of cells are connected in series is completed.

  The laser beam machine for carrying out the first irradiation step and the second irradiation step included in the laser processing method of the present embodiment has separation grooves 31 that divide the back electrode film 3 and the photoelectric conversion layer 2 into cell units. Laser light irradiation means for irradiating laser beams 43 and 44 for formation from the side of the laminated films 3, 2, 1 is provided.

  The laser beam irradiation means is directed to an optical system for propagating a laser oscillated by a laser oscillator, and a laser beam supplied via the optical system toward the laminated films 3, 2, 1 formed on the processing surface of the substrate 0. A processing nozzle 53 that emits laser light 43 and 44 is combined. The optical system can be configured using any optical element such as an optical fiber 54, a mirror, and a lens. The processing nozzle 53 is for lowering the laser beam downward from above the substrate 0 with respect to the substrate 0 with the film surface facing up.

  The processing nozzle 53 is provided so as to be capable of relative displacement with respect to the substrate 0. Typically, the separation grooves 11, 21, 31 formed in the thin films 1, 2, 3 can reciprocate in the extending Y-axis direction and are orthogonal to the Y-axis direction (photovoltaic elements or light emitting devices). The processing nozzle 53 is supported by a linear motor carriage or the like that can move by pitch feeding in the direction in which cells functioning as a body are arranged, the direction in which the cells are separated and the separation grooves 11, 21, and 31 are arranged. However, instead of moving the processing nozzle 53 in the X-axis direction and / or Y-axis direction with respect to the stationary substrate 0, the substrate 0 itself is moved in the X-axis direction and / or Y-axis direction with respect to the processing nozzle 53. It is also possible to make it.

  If the laser beam 43 irradiated in the first irradiation step and the laser beam 44 irradiated in the second irradiation step are emitted from the same processing nozzle 53, the processing nozzle 53 is moved in the Y-axis direction. By running or scanning (scanning) once from one end side to the other end side of the substrate 0 along the line, it is possible to complete the laser processing step (f) and complete the separation groove 31.

  FIG. 9 or FIG. 10 shows an internal configuration example of the processing nozzle 53. The processing nozzle 53 includes therein a spectroscopic unit 531 that splits a laser beam supplied to the processing nozzle 53 by an optical system such as an optical fiber 54 into a laser beam 43 and a laser beam 44.

  The spectroscopic means 531 of the processing nozzle 53 shown in FIG. 9 is coated so that one surface 532 is a dichroic mirror and the other surface 533 is a total reflection mirror. As is well known, the dichroic mirror 532 reflects light of a specific wavelength and transmits light of other wavelengths.

  An optical system such as an optical fiber 54 connected to the processing nozzle 53 propagates the superimposed light, which is a superposition of a plurality of laser beams 43 and 44 having different wavelengths, to the processing nozzle 53. The superimposed light that has reached the processing nozzle 53 strikes one surface 532 of the spectroscopic means 531, reflects the laser light 43 (or laser light 44) having a specific wavelength, and reflects the laser light 44 (or laser light having other wavelengths). Light 43) is incident. The laser beam 43 (or laser beam 44) incident on the spectroscopic means 531 is reflected by the other surface 533 of the spectroscopic means 531 and then reaches the one surface 532 again to be emitted to the outside.

  In turn, the spectroscopic means 531 of the processing nozzle 53 shown in FIG. 10 has a coating in which one surface 532 is a mirror that reflects a part of light (for example, a semi-reflective mirror) and the other surface 533 is a total reflection mirror. It is given.

  Unlike the example shown in FIG. 9, the optical system such as the optical fiber 54 connected to the processing nozzle 53 propagates a laser beam having a unique wavelength to the processing nozzle 53. The laser light that has reached the processing nozzle 53 strikes one surface 532 of the spectroscopic means 531, reflects a part of the laser light 43, and makes the remainder enter. The laser light incident on the spectroscopic means 531 is reflected by the other surface 533 of the spectroscopic means 531 and then reaches the one surface 532 again. A part of the laser light 44 is emitted from one surface 532 to the outside, and the rest is reflected into the spectroscopic means 531. Thereafter, on one surface 532, emission of part of the laser light and reflection of the remaining laser light are repeated. Compared with the laser beam 43 first reflected on the one surface 532, the output of the laser beam 44 emitted from the one surface 532 later is attenuated. When one surface 532 is a semi-reflective mirror, the output of the laser beam 44 is half of the output of the laser beam 43.

  In any case, the optical path is changed between the laser beam 43 and the laser beam 44 due to the action of the spectroscopic means 531, and the light is emitted from the processing nozzle 53 toward the processing surface of the substrate 0 in a state of being split. The optical paths of both laser beams 43 and 44 are separated along the Y-axis direction in which the separation groove 31 extends, but are not biased in the X-axis direction orthogonal to the Y-axis direction. A condensing lens (not shown) for condensing the laser beam 43 and focusing the laser beam 43 on the laser emission port of the processing nozzle 53 or near the emission port, and condensing the laser beam 44. It is desirable to dispose a condenser lens (not shown) that focuses the photoelectric conversion layer 2.

  If the machining nozzle 53 is moved or scanned relative to the substrate 0 along the Y-axis direction, as shown in FIG. 9 or FIG. 10 (the direction of running or scanning of the machining nozzle 53 is illustrated. After the laser beam 43 emitted from the machining nozzle 53 is irradiated onto the back electrode film 3, the laser beam 44 emitted from the machining nozzle 53 was once irradiated with the laser beam 43). As a result, the back electrode film 3 and the photoelectric conversion layer 2 are sequentially removed by both laser beams 43 and 44, and the separation groove 31 extending in the Y-axis direction is cut. Since one separation groove 31 is formed by one traveling or scanning of the processing nozzle 53, the tact time is greatly reduced.

  Incidentally, the optical system and the processing nozzle 53 constituting the laser beam irradiation means described above, an optical system for performing the step (b) (irradiating the laser beam 41 to form a separation groove in the transparent conductive film 1) and It may be shared with the processing nozzle 51. In this case, the step (b) and the step (f) can be performed by the same laser beam irradiation means.

  In addition, the optical system and the processing nozzle 53 constituting the laser beam irradiation means described above perform the step (d) (the optical system for irradiating the laser beam 42 to form the separation groove 21 in the photoelectric conversion layer 2). In addition, the processing nozzle 52 may be shared. Then, it becomes possible to implement a process (d) and a process (f) by the same laser beam irradiation means.

  The laser beam irradiation means for carrying out the step (b), the laser beam irradiation means for carrying out the step (d), and the laser beam irradiation means for carrying out the step (f) are a single laser processing machine. It is allowed to be implemented.

  For the convenience of partitioning a large number of cells by the separation grooves 11, 21, 31, as shown in FIG. 11, it is desirable that a plurality of processing nozzles 51, 52, 53 be arranged in the X-axis direction.

  In the laser processing method according to this embodiment, in order to perform the processing (f) of removing the plurality of stacked layers 3 and 2 having different materials from each other, the laser processing method is directed toward the uppermost layer 3 of the plurality of layers 3 and 2. A first irradiation step of irradiating at least the uppermost layer 3 by irradiating the laser beam 43, and a portion of the first irradiation step irradiated with the laser beam 43 in the vicinity of the portion irradiated with the laser beam 43 to irradiate the laser beam 44. And the second irradiation step of removing the layer 2 remaining below the first layer. That is, the laser beams 43 and 44 are irradiated in a plurality of times, and the plurality of layers 3 and 2 are removed.

  According to the present embodiment, the back electrode film 3 having a high processing threshold and the processing threshold while suppressing or avoiding damage to other layers below the photoelectric conversion layer 2, that is, the transparent conductive film 1 and the substrate base material 0. Therefore, it is possible to cut and remove the photoelectric conversion layer 2 having a low thickness, and to minimize the thermal influence on the product performance. Furthermore, the groove width (inner dimension in the X-axis direction) of the groove 31 formed by laser processing (f) can be reduced and the groove 31 can be thinned.

  The present invention is not limited to the embodiments described in detail above. In the above embodiment, in the laser processing (f), the wavelength or output of the laser beam 43 and the wavelength or output of the laser beam 44 are different from each other. This does not prevent the pulse width and the beam profile from being matched. For example, even if the wavelengths of both laser beams 43 and 44 are both 532 nm and the output, pulse width, and beam profile are equal to each other, laser processing (f) can be carried out successfully.

  In the above embodiment, in the laser processing (f), the laser beams 43 and 44 are divided into two times for convenience, and the layers 3 and 2 to be processed are irradiated. However, the laser light is irradiated three times or more. It may be. Also in this case, the wavelength, output, pulse width, or beam profile can be changed among the laser light irradiated for the first time, the laser light irradiated for the second time, the laser light irradiated for the third time, and so on.

The wavelengths, pulse widths, and the like of the laser beams 41, 42, 43, and 44 used in each of the laser processing step (b), the laser processing step (d), and the laser processing step (f) are not limited to those in the above embodiment. It may be a pulse laser or a continuous wave laser The materials of the first electrode film 1, the photoelectric conversion layer 2, and the second electrode film 3 are not limited to those in the above embodiment. In the above embodiment, the production of an organic solar cell and an organic electroluminescence device was considered, but the production method and laser processing machine according to the present invention can naturally be applied to various other products. For example, the present invention is applied to the manufacture of a silicon-based solar cell in which the photoelectric conversion layer 2 includes amorphous silicon and / or crystalline silicon (which is a concept encompassing single crystal silicon, polycrystalline silicon, and microcrystalline silicon). be able to. The present invention is suitable for processing (groove cutting or drilling) for removing these layers in a workpiece in which the uppermost layer is a metal film having a high processing threshold and a layer having a low processing threshold exists below the uppermost layer. It is.

  A separate intermediate layer may be laid between the first electrode film 1 and the photoelectric conversion layer 2 or between the photoelectric conversion layer 2 and the second electrode film 3.

  In addition, the specific configuration of each part, the procedure of processes, and the like can be variously modified without departing from the spirit of the present invention.

  The present invention can be applied to the production of organic solar cells, organic electroluminescent devices, and the like.

2 ... photoelectric conversion layer 3 ... second electrode film (back electrode film, metal film)
31 ... Separation groove 43 ... Laser light irradiated in the first irradiation step 44 ... Laser light irradiated in the second irradiation step

Claims (8)

A laser processing method for performing a process of removing a plurality of laminated layers having different materials from each other,
A first irradiation step of irradiating a laser beam toward the uppermost layer of the plurality of layers to remove at least the uppermost layer;
A second irradiation step of irradiating the vicinity of the portion irradiated with the laser beam in the first irradiation step and removing a layer remaining below the uppermost layer. The laser beam irradiated in the first irradiation step and the laser beam irradiated in the second irradiation step are in phase in at least one of wavelength, output, pulse width, repetition frequency, beam profile, or processing speed. The laser processing method according to claim 1, which is different. The laser processing method according to claim 1, wherein the uppermost layer is a metal film. The laser processing method according to claim 1, wherein the layer existing below the uppermost layer is a photoelectric conversion layer. 5. The laser according to claim 4, wherein the object to be processed is a silicon-based solar cell, an organic-based solar cell or an organic electroluminescence device, and both the metal film as the uppermost layer and the photoelectric conversion layer existing below the uppermost layer are removed. Processing method. It is used for carrying out the laser processing method according to claim 1, 2, 3, 4 or 5,
Laser light irradiation means for irradiating a laser beam toward the uppermost layer in the first irradiation step, and a position irradiated with the laser light in the first irradiation step in the second irradiation step A laser processing machine comprising a laser beam irradiation means for irradiating a laser beam in the vicinity. The laser beam irradiated in the first irradiation step and the laser beam irradiated in the second irradiation step are different from each other in at least one of a wavelength, an output, a pulse width, and a beam profile. The laser processing machine described. The laser processing machine according to claim 6 or 7, wherein the uppermost layer is a metal film.

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