TWI477342B - Laser scribing method - Google Patents

Description

Laser cutting method

The present invention is a laser cutting method, and more particularly to a method for cutting a structure of a thin film photoelectric conversion element to remove respective film layer structures of a thin film photoelectric conversion element to form an insulating trench.

Solar energy is an energy source that never runs out and is non-polluting. It has always been the focus of attention when solving the problems of pollution and shortage faced by petrochemical energy. Among them, the solar cell can directly convert solar energy into electric energy, which has become a very important research topic at present. The solar cell utilizes the photoelectric effect to output voltage and current. It does not generate greenhouse gases such as carbon dioxide during power generation, and does not pollute the environment. It is a renewable and environmentally friendly power generation method.

At present, in the solar cell market, batteries using single crystal germanium and polycrystalline germanium account for more than 90%. However, these solar cells require the use of tantalum wafers having a thickness of about 150 to 350 micrometers as a material, which is costly. Furthermore, since the raw materials of solar cells are made of high-quality twin crystal ingots, they have become increasingly insufficient in recent years due to the obvious growth in usage. Therefore, the development of thin film solar cells has become a new development direction. Moreover, the thin film solar cell has the advantages of low cost, easy large-area production, and simple modular process.

In the prior art, a general thin film solar cell is at least made of a transparent substrate. A (transparent substrate), a front electrode layer, an absorber layer, and a back electrode layer are sequentially stacked. However, conventional solar cell cutting is performed by scribing, polishing, and The process of washing and drying needs to be processed again. The process is very cumbersome and time-consuming. In view of this, the laser scribing method can be used to cut or partition the surface of the solar cell, which can effectively improve the old and cumbersome processing. Process.

At present, some related patents have disclosed related technologies for laser cutting of thin film solar cells. For example, Japanese Patent No. 3,815,875 discloses the use of laser light to cut a semiconductor layer to form a separation trench; U.S. Patent No. 6,858,461 discloses the use of a laser cutting method. In addition to a portion of the metal electrode layer and the photoelectric conversion layer, at least one trench is formed; US Pat. No. 7,750,233 discloses the manner in which the laser beam sequence is adjusted to obtain a separation trench.

However, when cutting the insulating trench by laser cutting, the process of cutting the insulating trench is different according to the nature of each film, and processing is performed according to a laser of a specific wavelength to form an insulating trench. Laser cutting is performed at a high temperature, and it is easy to cause conductive particles in the back electrode layer or melt and accumulate inside the trench due to thermal effects when the film layer is cut, causing short circuit of the front and back electrode layers; or amorphous 光 of the light absorbing layer Recrystallization occurs at the sidewall of the trench at a high temperature to form a low-resistance microcrystalline germanium, which increases the leakage current, thereby affecting the process yield and the efficiency of the solar cell.

The embodiment of the present invention is directed to a laser cutting method capable of removing each film layer structure of a thin film photoelectric conversion element to form an insulating trench and removing conductive particles remaining in the insulating trench to reduce short circuit or The leakage current situation occurs, and the laser cutting method proposed by the present invention can overcome the conventional technique and cannot break the thickness of the light absorbing layer. If it is larger than 1.5 μm, it cannot be processed.

The present invention discloses a laser cutting method for cutting a thin film photoelectric conversion element, wherein the thin film photoelectric conversion element is formed by at least a substrate, a front electrode layer, a light absorbing layer and a back electrode layer being sequentially stacked from bottom to top. The shot cutting method comprises the steps of: irradiating a first laser beam having a first wire diameter onto a first region of the thin film photoelectric conversion element to remove the back electrode layer and the light absorbing layer in the first region. Next, the second laser beam having the second wire diameter is irradiated to the second region in the first region, and the front electrode layer in the second region is removed, wherein the wavelength of the second laser beam is greater than the first laser The wavelength of the beam, and the second line diameter is smaller than the first line diameter. The third laser beam having the third wire diameter is irradiated to the second region, wherein the wavelength of the third laser beam is smaller than the wavelength of the second laser beam, and the third wire diameter is greater than the second wire diameter.

Further, the third laser beam can remove a plurality of residual particles in the second region.

Further, the plurality of residual particles may be conductive elements included in the front electrode layer and the back electrode layer.

Further, the conductive element may include molybdenum (Mo), aluminum (Al), silver (Ag), platinum (Pt), zinc (Zn), tin (Sn), tin dioxide (SnO 2 ), indium tin oxide (ITO). Zinc oxide (ZnO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO) or indium zinc oxide (IZO).

Further, the material of the substrate may include soda glass, potassium glass, aluminum magnesium glass, lead glass, borosilicate glass or quartz glass.

Further, the material of the front electrode layer may include tin oxide (SnO 2 ), indium tin oxide (ITO), zinc oxide (ZnO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO) or indium zinc oxide (IZO). .

Further, the material of the back electrode layer may include molybdenum (Mo), aluminum (Al), silver (Ag), platinum (Pt), zinc (Zn), tin (Sn), titanium (Ti), nickel (Ni), Zinc oxide or tin oxide.

Further, the material of the light absorbing layer may include amorphous germanium (a-Si), microcrystalline germanium (μc-Si), amorphous germanium (a-SiGe), microcrystalline germanium (μc-SiGe), germanium Cadmium (CdTe), indium copper selenide (CuInSe2), copper indium gallium selenide (CIGS), indium phosphide (InP), gallium arsenide (GaAs), mercury cadmium telluride (HgCdTe) or indium gallium Arsenic (InGaAs).

Further, the thickness of the light absorbing layer may be greater than 1.5 μm.

S1~S3‧‧‧ Process steps

1‧‧‧Substrate

2‧‧‧ front electrode layer

3‧‧‧Light absorbing layer

4‧‧‧Back electrode layer

L1‧‧‧first laser beam

L2‧‧‧second laser beam

L3‧‧‧third laser beam

Ld1‧‧‧ first line diameter

Ld2‧‧‧ second line diameter

Ld3‧‧‧ third line diameter

A1‧‧‧ first area

A2‧‧‧Second area

90‧‧‧Residual particles

The above and other features and advantages of the present invention will become more apparent from the detailed description of the exemplary embodiments of the invention. 2 is a schematic view showing the steps of the laser cutting method of the present invention; and FIG. 3 is an SEM image of a preferred embodiment of the laser cutting method of the present invention.

The technical features, contents, and advantages of the present invention, as well as the advantages thereof, can be understood by the present inventors, and the present invention will be described in detail with reference to the accompanying drawings. The subject matter is only for the purpose of illustration and description. It is not intended to be a true proportion and precise configuration after the implementation of the present invention. Therefore, the scope and configuration relationship of the attached drawings should not be interpreted or limited. First described.

Please refer to FIG. 1 , which is a flow chart of the laser cutting method of the present invention. The steps of the cutting method are as follows. In step S1, a first laser beam having a first wire diameter is irradiated onto the first region of the thin film photoelectric conversion element to remove the back electrode layer and the light absorbing layer in the first region. Next, in step S2, the second laser beam having the second wire diameter is irradiated to the second region in the first region, and the front electrode layer in the second region is removed, wherein the wavelength of the second laser beam is greater than The wavelength of a laser beam, and the second line diameter is smaller than the first line diameter.

In step S3, a third laser beam having a third wire diameter is irradiated to the second region to remove residual particles remaining in the second region, wherein the wavelength of the third laser beam is smaller than that of the second laser beam. The wavelength, and the third line diameter is greater than the second line diameter.

Please refer to FIG. 2, which is a schematic diagram of the steps of the laser cutting method of the present invention. As can be seen from FIG. 2(A), the thin film photoelectric conversion element is formed by stacking at least the substrate 1, the front electrode layer 2, the light absorbing layer 3, and the back electrode layer 4 in sequence, wherein the material of the substrate 1 contains soda glass. Various transparent optical glasses such as potassium glass, aluminum-magnesium glass, lead glass, borosilicate glass or quartz glass; the material of the front electrode layer 2 includes tin dioxide (SnO2), indium tin oxide (ITO), and zinc oxide (ZnO). a variety of conductive and transparent metal oxides such as aluminum zinc oxide (AZO), gallium zinc oxide (GZO) or indium zinc oxide (IZO); the material of the light absorbing layer 3 comprises amorphous germanium (a-Si) , microcrystalline germanium (μc-Si), amorphous germanium (a-SiGe), microcrystalline germanium (μc-SiGe), cadmium telluride (CdTe), indium copper selenide (CuInSe2), copper indium gallium selenide (CIGS, copper indium gallium selenide), indium phosphide (InP), gallium arsenide (GaAs), mercury cadmium telluride (HgCdTe) or indium gallium arsenide (InGaAs) and other sulfhydryl groups, compounds and organic groups with photoelectric effect And other materials; the material of the back electrode layer 4 includes molybdenum (Mo), aluminum (Al), silver (Ag), platinum (Pt), zinc (Zn), tin (Sn), titanium (Ti), nickel (Ni) Various conductive elements such as zinc oxide or tin oxide Compounds thereof.

As can be seen from Fig. 2 (B1), in the region where the thin film photoelectric conversion element is to be cut out of the insulating trench, the laser light emitting head is placed under the substrate 1 after being positioned by a precise positioning mechanism (not shown). The substrate 1 is made of a transparent optical glass material, and the laser beam can be directly focused upward from the bottom of the substrate 1 to be focused on the target region. According to the properties of the respective layers, a laser of a specific wavelength is selected for processing. The first laser beam L1 having the first wire diameter Ld1 is irradiated to the first region A1 in the thin film photoelectric conversion element to decompose, vaporize or burst the material in the focus region by the high power of the laser to remove The film structure material of the light absorbing layer 3 and the back electrode layer 4 in the first region A1.

As can be seen from Fig. 2 (B2), the film structure material of the light absorbing layer 3 and the back electrode layer 4 in the first region A1 has been removed by the first laser beam L1, but the first region A1 is The blasting residual particles or vaporized decomposition gas of the light absorbing layer 3 and the back electrode layer 4, which are removed by the power of the first laser beam L1, can be vacuum-extracted and discharged by a dust suction device (not shown). Maintain operator industrial safety.

As can be seen from Fig. 2 (C1), the second laser beam L2 having the second wire diameter Ld2 is irradiated to the second region A2, while the second region A2 is located within the range of the first region A1, and is directed to the front electrode layer. 2 performing material removal, wherein the wavelength of the second laser beam L2 is greater than the wavelength of the first laser beam L1, and the second wire diameter Ld2 is smaller than the first wire diameter Ld1.

As can be seen from Fig. 2 (C2), although the structural material of the front electrode layer 2 in the second region A2 has been removed by the high temperature generated by the second laser beam L2, it still remains at the edge of the insulating trench. It is found that the conductive elements in the front electrode layer 2 or the back electrode layer 4 are present in the residual particle 90 state or there is a conductive element fused to the wall edge of the insulating trench, thereby causing a short circuit of the front and back electrode layers, wherein the conductive element Containing molybdenum (Mo), aluminum (Al), silver (Ag), platinum (Pt), zinc (Zn), tin (Sn), titanium (Ti), nickel (Ni), two Tin oxide (SnO 2 ), indium tin oxide (ITO), zinc oxide (ZnO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO) or indium zinc oxide (IZO), etc., front electrode layer 2 or back electrode layer 4 The material type included in it.

As can be seen from Fig. 2 (D1), the inventive innovation utilizes a third laser beam L3 having a third wire diameter Ld3 to illuminate the second region A2, and the third wire diameter Ld3 is greater than the second wire diameter Ld2 to cover the front. The second region A2 in the electrode layer 2 is irradiated by the third laser beam L3 to remove residual particles 90 of the conductive element which causes short-circuiting of the front and back electrode layers.

As can be seen from Fig. 2 (D2), the innovation of the present invention utilizes three laser beams to remove the film structure of the thin film photoelectric conversion element to form an insulating trench and to remove residual residues in the insulating trench. The residual particles 90 of the conductive element are used to reduce the occurrence of short circuit or leakage current.

(B1) and (B2) in FIG. 2 are explanatory diagrams of step S1 in FIG. 1; (C1) and (C2) are explanatory diagrams of step S2 in FIG. 1; (D1) and (D2) It is a schematic diagram of the step S3 in Fig. 1; the technical features of the laser cutting method of the present invention are explained in detail by the drawings.

Please refer to FIG. 3, which is a Scanning Electron Microscopy (SEM) image of a preferred embodiment of the laser cutting method of the present invention. According to the steps of the laser cutting method of the present invention, the thin film photoelectric conversion element scribing cutting experiment is performed, and the edge of the insulating trench is observed through SEM, and the section of the insulating trench is found to be straight, and then analyzed by X-ray energy spectrum dispersion. The elemental analysis (Energy Dispersive Spectrometry of X-ray, EDS) was carried out, and it was found from the measurement points in the insulating trench that no residual particles were present.

Furthermore, the laser cutting method proposed by the present invention can overcome the problem that the conventional technique cannot break through the thickness of the light absorbing layer of more than 1.5 μm and cannot be processed.

Looking at the above, it can be seen that the present invention has achieved the desired effect under the prior art, and is not familiar to those skilled in the art. Moreover, the present invention has not been disclosed before the application, and it has Progressive and practical, it has already met the requirements for patent application, and has filed a patent application according to law. You are requested to approve the application for this invention patent to encourage creation.

The embodiments described above are merely illustrative of the technical spirit and the features of the present invention, and the objects of the present invention can be understood by those skilled in the art, and the scope of the present invention cannot be limited thereto. That is, the equivalent variations or modifications made by the spirit of the present invention should still be included in the scope of the present invention.

1‧‧‧Substrate

2‧‧‧ front electrode layer

3‧‧‧Light absorbing layer

4‧‧‧Back electrode layer

L1‧‧‧first laser beam

L2‧‧‧second laser beam

L3‧‧‧third laser beam

Ld1‧‧‧ first line diameter

Ld2‧‧‧ second line diameter

Ld3‧‧‧ third line diameter

A1‧‧‧ first area

A2‧‧‧Second area

90‧‧‧Residual particles

Claims (8)

A laser cutting method for cutting a thin film photoelectric conversion element, wherein the thin film photoelectric conversion element is formed by at least a substrate, a front electrode layer, a light absorbing layer and a back electrode layer being sequentially stacked from bottom to top. The laser cutting method comprises the steps of: irradiating a first laser beam having a first wire diameter onto a first region of the thin film photoelectric conversion element to remove the back electrode in the first region; a layer and the light absorbing layer; irradiating a second laser beam having a second wire diameter to a second region in the first region, and removing the front electrode layer in the second region, wherein the The wavelength of the second laser beam is greater than the wavelength of the first laser beam, and the second line diameter is smaller than the first line diameter; and a third laser beam having a third line diameter is irradiated to the first a second region, and the third laser beam removes a plurality of residual particles in the second region, wherein a wavelength of the third laser beam is smaller than a wavelength of the second laser beam, and the third line is Greater than the second wire diameter. The laser cutting method according to claim 1, wherein the plurality of residual particles are a conductive element included in the front electrode layer and the back electrode layer. The laser cutting method according to claim 2, wherein the conductive element comprises molybdenum (Mo), aluminum (Al), silver (Ag), platinum (Pt), zinc (Zn), tin (Sn) Titanium (Ti), nickel (Ni), tin dioxide (SnO2), indium tin oxide (ITO), zinc oxide (ZnO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO) or indium zinc oxide (IZO) ). The laser cutting method according to claim 1, wherein the substrate material The system consists of soda glass, potassium glass, aluminum-magnesium glass, lead glass, borosilicate glass or quartz glass. The laser cutting method according to claim 1, wherein the material of the front electrode layer comprises tin dioxide (SnO 2 ), indium tin oxide (ITO), zinc oxide (ZnO), and aluminum zinc oxide (AZO). , gallium zinc oxide (GZO) or indium zinc oxide (IZO). The laser cutting method according to claim 1, wherein the material of the back electrode layer comprises molybdenum (Mo), aluminum (Al), silver (Ag), platinum (Pt), zinc (Zn), tin. (Sn), titanium (Ti), nickel (Ni), zinc oxide or tin oxide. The laser cutting method according to claim 1, wherein the material of the light absorbing layer comprises amorphous germanium (a-Si), microcrystalline germanium (μc-Si), amorphous germanium (a-SiGe). ), microcrystalline germanium (μc-SiGe), cadmium telluride (CdTe), indium copper selenide (CuInSe2), copper indium gallium selenide (CIGS), indium phosphide (InP), arsenic Gallium (GaAs), mercury cadmium telluride (HgCdTe) or indium gallium arsenide (InGaAs). The laser cutting method according to claim 1, wherein the light absorbing layer has a thickness greater than 1.5 μm.