JP5610912B2 - Laser processing apparatus and laser processing method - Google Patents

Description

  The present invention relates to a method of LED (Laser Edge Deletion) in a manufacturing process of a thin film solar cell, and a processing apparatus therefor.

  Thin-film solar cells, which are the mainstream today, are produced by depositing a transparent conductive film, a silicon-based power generation layer (absorption layer), and a back electrode film on a substrate. As shown in FIG. 2, these laminated films 7, 8, and 9 are sealed by laminating a laminate film 11 from the back side, but are positioned on the outer peripheral edge of the substrate 10 prior to the laminating process. It is necessary to remove the laminated films 7, 8, and 9 (for example, refer to the following patent document).

The removal process of this laminated film performed by laser scribing is an LED. In the LED, normally, solid-state lasers such as Nd: YAG, Nd: YVO ₄ , Yb: Glass, and Yb: YAG are used. This type of solid-state laser light has a wavelength in the range of 1030 nm to 1100 nm, and is suitable for removing a TCO (Transparent Conductive Oxide) film used as a transparent conductive film.

  However, on the other hand, it is not suitable for removing the silicon film that is the power generation layer. This is because the absorption wavelength band of amorphous silicon (a-Si) is 300 nm to 700 nm, and the absorption wavelength band of microcrystalline silicon (μc-Si) is 500 nm to 900 nm, both of which hardly absorb the solid laser light.

  Therefore, the laminated film cannot be removed sufficiently, and the appearance may be clearly disturbed in the finish.

  Although it is conceivable to significantly increase the output of the solid-state laser in order to ensure the removal of the laminated film, it is not preferable because it increases the cost.

JP 2010-074071 A

  The main object of the present invention is to reliably remove the laminated film and make the finish beautiful in an LED of a thin film solar cell.

In the present invention, a multi-layered thin-film solar in which a power generation layer including a transparent conductive film, amorphous silicon, and crystalline silicon (a concept encompassing single crystal silicon, polycrystalline silicon, and microcrystalline silicon) and a back electrode film are stacked. Irradiating a transparent conductive film with a first laser beam belonging to a wavelength band that is absorbed by the transparent conductive film in an LED that processes the battery to remove the transparent conductive film, the power generation layer, and the back electrode film The power generation layer and the back electrode film are removed by irradiating the power generation layer with a second laser light having a wavelength shorter than that of the first laser light belonging to the wavelength band absorbed by the power generation layer. It was decided to remove. The second laser beam is irradiated after being formed into a projection size suitable for a processing width which is a width of a region where the transparent conductive film, the power generation layer and the back electrode film are to be removed, while the first laser beam is irradiated. Irradiates the region of the processing width through a galvano scanner capable of swinging and moving the laser optical axis after narrowing the projection shape to be narrower than the processing width.

  The laser processing apparatus for carrying out the LED according to the present invention includes a laser light source that outputs a first laser beam that belongs to a wavelength band that is absorbed by the transparent conductive film and that can remove the transparent conductive film, and a power generation layer absorbs the laser light source. A laser light source that outputs a second laser light having a shorter wavelength than the first laser light that belongs to the wavelength band and can remove the power generation layer, a support that supports the thin-film solar cell, the first laser light, and An optical system for guiding the second laser beam and irradiating the thin film solar cell supported by the support.

  The first laser beam is preferably a laser beam having a wavelength of 980 nm or more, with emphasis on the removal of the transparent conductive film.

  The second laser beam is preferably a laser beam having a wavelength of 900 nm or less, with emphasis on removal of the power generation layer. At this time, a laser beam belonging to a wavelength band absorbed by crystalline silicon may be adopted as the second laser beam, and the amorphous silicon co-generation layer may be removed by irradiating the crystalline silicon with this.

  When the thin-film solar cell is formed by laminating a transparent conductive film, a power generation layer, and a back electrode film in this order on a transparent substrate, the second laser beam is transmitted from the transparent substrate side to the transparent substrate. And transmitting the transparent conductive film to irradiate the power generation layer, and transmitting the first laser light from the transparent substrate side through the transparent substrate to irradiate the transparent conductive film.

  First, the power generation layer is irradiated with the second laser light to remove the power generation layer and the back electrode film, and then the first laser light is applied to the transparent conductive film where the power generation layer and the back electrode film are removed. If the transparent conductive film is removed by irradiation, the power generation layer, the back electrode film, and the transparent conductive film can be sufficiently removed to realize processing with little residue.

  ADVANTAGE OF THE INVENTION According to this invention, in LED of a thin film solar cell, it becomes possible to remove a laminated film reliably and to make a finish beautiful.

The perspective view which shows schematic structure of the laser processing apparatus of one Embodiment of this invention. The perspective view which shows the thin film solar cell used as the object of the process by the laser processing apparatus. The sectional side view which shows the thin film solar cell used as the object of the process by the laser processing apparatus. The perspective view which shows schematic structure of the modification of this invention. The perspective view which shows schematic structure of the reference example relevant to this invention.

  An embodiment of the present invention will be described with reference to the drawings. The laser processing apparatus of this embodiment is located at the outer peripheral edge of a substrate 10 with respect to a multi-layered thin film solar cell in which a transparent conductive film 7, a power generation layer 8, and a back electrode film 9 are stacked on a substrate 10. In other words, the LED for removing the laminated films 7, 8, 9 in the band-like region facing the four sides of the substrate 10 is implemented.

  FIG. 3 illustrates the structure of a multi-layered thin film solar cell. This thin-film solar cell includes a glass substrate 10 as a transparent substrate 10, a TCO film 7 as a transparent conductive film, and amorphous silicon (p-type a-Si, intrinsic a-Si, n-type a-Si) 81 as a power generation layer 8. And a microcrystalline silicon (p-type μc-Si, intrinsic μc-Si, n-type μc-Si) 82 and a metal film 9 as a back electrode film are formed and laminated in this order.

  As shown in FIG. 1, the laser processing apparatus of this embodiment includes a laser light source 1 that outputs a first laser beam, a laser light source 3 that outputs a second laser beam, and a support 5 that supports a thin-film solar cell. And optical systems 2 and 4 for directing the first laser beam and the second laser beam to irradiate the thin film solar cell supported by the support 5. Incidentally, the conveyance direction of the substrate 10 supported by the support 5 or the movement direction of the processing nozzles 21 and 41 with respect to the substrate 10 is indicated by white arrows in the figure.

The first laser light belongs to a wavelength band of 980 nm or more and can remove the TCO film 7. The light source 1 is a solid-state laser (disk laser or fiber laser) such as Nd: YAG (wavelength 1064 nm), Nd: YVO ₄ (wavelength 1064 nm), Yb: Glass (wavelength 1030 to 1100 nm), Yb: YAG (wavelength 1030 nm). May be included). Many of these solid-state laser light sources 1 are distributed in the market, and it is easy to ensure a high output necessary and sufficient for scribing the TCO film 7.

  In turn, the second laser light belongs to a wavelength band of 900 nm or less shorter than the first laser light, and the power generation layer 8 of the silicon film including the amorphous silicon 81 and the microcrystalline silicon 82 can be removed. Examples of the light source 3 include various semiconductor lasers (diode lasers) or the second harmonics of the above-described solid-state laser having a wavelength of 1000 nm or more. In the present embodiment, a semiconductor laser having a wavelength of 800 nm is employed as the second laser light. Incidentally, it does not prevent the excitation light source of the solid-state laser that becomes the first laser light from being used as the light source 3 of the second laser light.

  The optical systems 2 and 4 are provided with processing nozzles 21 and 41 for emitting laser light toward the thin films 7, 8 and 9 of the substrate 10 to be processed, and laser light output by the laser light sources 1 and 3, And various optical elements (optical fibers, mirrors, lenses, etc.) 22 and 42 leading to 41. In the present embodiment, the processing nozzle 21 that emits the first laser light and the processing nozzle 42 that emits the second laser light are separated, and the irradiation position of the first laser light and the second laser light are further separated. Is spaced apart from the irradiation position.

  The processing nozzle 21 is provided with a galvano scanner capable of swinging the laser optical axis for the purpose of removing the TCO film 7 with near-infrared laser light whose power density is increased by reducing the projection shape to a small diameter. The TCO film 7 at the outer peripheral edge can be removed in a strip shape.

  The processing nozzle 41 emits a semiconductor laser beam whose projection shape is an elongated square (about 1 cm × 150 μm). The laser light is shaped into a projection size suitable for the processing width of the outer peripheral edge of the substrate 10 (width for removing the silicon film of the power generation layer 8) using optical elements such as various lenses and mirrors. Layer 8 is irradiated. On the processing nozzle 41 side, a galvano scanner is not necessary.

  The optical systems 22 and 42 are typically optical fibers that connect the laser light sources 1 and 3 and the processing nozzles 21 and 41. Of course, what optical elements are arranged on the optical path from the laser light sources 1 and 3 to the processing nozzles 21 and 41 is arbitrary, and is not limited uniquely.

  During the LED processing, the substrate 10 is displaced relative to the processing nozzles 21 and 41. For this purpose, for example, an XY stage capable of moving the substrate 10 in a plane (in both X and Y directions) is adopted as the support 5. However, a movable mechanism other than the XY stage may be mounted on the support 5, or the support 5 is fixed and the machining nozzles 21 and 41 are moved relative to the support 5 instead. It doesn't matter.

  As shown in FIG. 1, each processing nozzle 21, 41 has a laser beam upward from below the substrate 10 that is supported with the surface on which the laminated films 7, 8, 9 are formed facing upward. Fire. However, conversely, the substrate 10 is supported with the surface on which the laminated films 7, 8, 9 are formed facing down, and the processing nozzles 21, 41 are disposed above the substrate 10. It is also conceivable to take a mode in which laser light is emitted downward.

  The second laser light emitted from the processing nozzle 41 passes through the glass substrate 10 and the TCO film 7 and is applied to the power generation layer 8. In particular, in the present embodiment, a multi-layered solar cell in which microcrystalline silicon 82 is stacked on amorphous silicon 81 is a processing target, and the focal point of the second laser light is brought close to the layer of microcrystalline silicon 82. I have to. The absorption band of microcrystalline silicon 82 is 500 nm to 900 nm, the absorption band of amorphous silicon 81 is 300 nm to 700 nm, and the wavelength of the second laser beam is not in the absorption band of amorphous silicon 81. However, by absorbing the second laser light into the microcrystalline silicon 82, the amorphous silicon 81, the microcrystalline silicon 82, and the metal film 9 can be blown off and removed by a thermal phenomenon.

  According to the present embodiment, the laser light source 1 that outputs the first laser light that belongs to the wavelength band that the transparent conductive film 7 absorbs and can remove the transparent conductive film 7, and the wavelength band that the power generation layer 8 absorbs. A laser light source 2 that outputs a second laser beam having a shorter wavelength than the first laser beam capable of removing the power generation layer 8, a support 5 that supports the thin-film solar cell, the first laser beam, and the A laser processing apparatus including optical systems 2 and 4 for guiding the second laser light and irradiating the thin film solar cell supported by the support 5 is configured, and the second laser light is applied to the power generation layer 8. This is removed by irradiating the transparent conductive film 7 with the first laser beam, so that the layered film 7, 8, 9 is irradiated with the solid laser beam. Compared to the laminated film 7, 8, 9 can be removed sufficiently, the finish is The Li. Furthermore, tact-up can be realized as compared with the conventional method, and it is effective in reducing power consumption.

  Since the first laser beam is a laser beam having a wavelength of 980 nm or more, it is easy to increase the output, and the transparent conductive film 7 can be effectively removed. Further, such first laser light is unlikely to adversely affect the power generation layer 8.

  Since the second laser beam is a laser beam having a wavelength of 900 nm or less, the power generation layer 8 and the back electrode film 9 can be effectively removed.

  Since the second laser beam is a laser beam belonging to a wavelength band that is absorbed by the crystalline silicon 82, it is more advantageous in terms of cost than using a laser (such as a green laser) having a wavelength band that is absorbed well by the amorphous silicon 81. It becomes.

  The thin-film solar cell is formed by laminating a transparent conductive film 7, a power generation layer 8, and a back electrode film 9 in this order on a transparent substrate 10, and the optical systems 2 and 4 transmit the second laser beam to the second laser beam. The transparent substrate 10 and the transparent conductive film 7 are transmitted from the transparent substrate 10 side to irradiate the power generation layer 8, and the first laser light is transmitted from the transparent substrate 10 side through the transparent substrate 10. Since the transparent conductive film 7 is irradiated, residues and redeposits on the substrate 10 can be reduced.

  The optical systems 2 and 4 first irradiate the power generation layer 8 with the second laser light to remove the power generation layer 8 and the back electrode film 9, and then apply the first laser light to the power generation layer 8 and the back surface. Since the transparent conductive film 7 is removed by irradiating the transparent conductive film 7 where the electrode film 9 has been removed, only the first transparent conductive film 7 exposed by removing the power generation layer 8 is exposed. It is possible to remove the laser beam without fail without irradiating it with laser light.

  The present invention is not limited to the embodiment described in detail above. In the above-described embodiment, the first laser light and the second laser light are emitted from the separate processing nozzles 21 and 41 and are irradiated to different irradiation positions on the substrate 10. In other words, the first laser beam is irradiated on the region of the substrate 10 where the power generation layer 8 and the metal film 9 have already been removed by the irradiation of the second laser beam. On the other hand, as shown in FIG. 4, the irradiation position of the first laser beam on the substrate 10 and the irradiation position of the second laser beam on the substrate 10 may be overlapped.

  Alternatively, as shown in FIG. 5, it may be possible to partially share the optical system 6 that guides the first laser beam and the optical system that guides the second laser beam. That is, a single processing nozzle 61 is used, and the first laser is incident on the optical path from the laser light sources 1 and 2 to the processing nozzle 61 (by entering the same optical fiber 62 connected to the processing nozzle 61). The light and the second laser light may be superimposed. Thereby, the irradiation position of the first laser beam on the substrate 10 and the irradiation position of the second laser beam on the substrate 10 inevitably overlap each other. The processing nozzle 61 is also provided with a galvano scanner so that the overlapped laser light can scan a band-like region where the laminated films 7, 8, and 9 on the substrate 10 are to be removed.

  Other specific configurations of each part can be variously modified without departing from the spirit of the present invention.

  The present invention can be used as a processing apparatus for performing laser scribing or ablation of a thin film in a manufacturing process of a solar cell panel.

DESCRIPTION OF SYMBOLS 1 ... First laser light source 2, 4, 6 ... Optical system 3 ... Second laser light source 5 ... Support 7 ... Transparent conductive film 8 ... Power generation layer 9 ... Back electrode film 10 ... Substrate

Claims (7)

To remove the transparent conductive film, power generation layer, and back electrode film from a multi-layered thin film solar cell in which a transparent conductive film, a power generation layer containing amorphous silicon and crystalline silicon, and a back electrode film are stacked The laser processing apparatus of
A laser light source that outputs a first laser beam that belongs to a wavelength band that is absorbed by the transparent conductive film and that can remove the transparent conductive film, and a first laser beam that belongs to the wavelength band that is absorbed by the power generation layer and can remove the power generation layer A laser light source that outputs a second laser beam having a shorter wavelength than
A support for supporting the thin film solar cell;
An optical system for directing the first laser beam and the second laser beam to irradiate the thin film solar cell supported by the support , and
While the second laser beam is irradiated after being formed into a projection size suitable for a processing width which is a width of a region where the transparent conductive film, the power generation layer and the back electrode film should be removed,
The first laser beam is irradiated so as to scan the region of the processing width through a galvano scanner capable of swinging and moving the laser optical axis after narrowing the projection shape to be narrower than the processing width. Processing equipment. The laser processing apparatus according to claim 1, wherein the first laser beam is a laser beam having a wavelength of 980 nm or more. The laser processing apparatus according to claim 1, wherein the second laser light is a laser light having a wavelength of 900 nm or less. The laser processing apparatus according to claim 3, wherein the second laser beam is a laser beam belonging to a wavelength band absorbed by crystalline silicon. The thin film solar cell is obtained by laminating a transparent conductive film, a power generation layer, and a back electrode film in this order on a transparent substrate,
The optical system transmits the second laser light from the transparent substrate side through the transparent substrate and the transparent conductive film and irradiates the power generation layer, and the first laser light from the transparent substrate side. The laser processing apparatus according to claim 1, wherein the transparent conductive film is irradiated through the transparent substrate. The optical system first irradiates the power generation layer with the second laser light to remove the power generation layer and the back electrode film, and then removes the power generation layer and the back electrode film from the first laser light. The laser processing apparatus according to claim 1, wherein the transparent conductive film is removed by irradiating the transparent conductive film. A laser that performs processing to remove a transparent conductive film, a power generation layer, and a back electrode film on a multi-layer thin film solar cell in which a transparent conductive film, a power generation layer containing amorphous silicon and crystalline silicon, and a back electrode film are stacked A processing method,
While removing the transparent conductive film by irradiating the transparent conductive film with the first laser beam belonging to the wavelength band absorbed by the transparent conductive film,
The power generation layer and the back electrode film are removed by irradiating the power generation layer with a second laser light having a wavelength shorter than that of the first laser light belonging to the wavelength band absorbed by the power generation layer,
While the second laser beam is irradiated after being formed into a projection size suitable for a processing width which is a width of a region where the transparent conductive film, the power generation layer and the back electrode film should be removed,
The first laser beam is irradiated so as to scan the region of the processing width through a galvano scanner capable of swinging the laser optical axis after narrowing the projection shape to be narrower than the processing width. A laser processing method characterized by the above.

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