TWI499065B - Method for manufacturing solar cell - Google Patents

Description

Solar cell manufacturing method

The present invention relates to a method of manufacturing a solar cell, and more particularly to a method of manufacturing an electrode of a solar cell.

A typical solar cell includes a semiconductor substrate, an anti-reflection layer, and a finger electrode pattern. Wherein the anti-reflection layer is on the semiconductor substrate, and the finger electrode pattern is on the anti-reflection layer.

In a general solar cell manufacturing method, a finger electrode pattern is first formed on a antireflection layer of a semiconductor substrate using a metal electrode material. Next, the metal electrode material of the finger electrode pattern is sintered, and the metal electrode material is cured and attached to the antireflection layer.

However, in the sintering step, the surface of the metal electrode material is oxidized to form an unnecessary oxide layer. Since the oxide layer has a high sheet resistance (Rs), the electrical conductivity of the solar cell is poor, resulting in loss of electrical energy. Therefore, there is a need for a new method of manufacturing solar cells to solve the shortcomings of conventional solar cell manufacturing methods.

The invention provides a method for manufacturing a solar cell, which solves the defect of the manufacturing method of the conventional solar cell and effectively reduces the sheet resistance value of the solar cell.

One aspect of the present invention provides a method of manufacturing a solar cell. The manufacturing method includes providing a semiconductor substrate having a light-incident surface and a backlight surface opposite to the light-incident surface, wherein the light-receiving surface has an anti-reflection layer. A metal electrode material is formed on the anti-reflection layer to form a first electrode pattern. The first electrode pattern is sintered. An oxide layer formed on the surface of the metal electrode material in the sintered first electrode pattern is removed. A plating layer is formed on the metal electrode material through which the oxide layer is removed to form a front electrode of the solar cell.

According to an embodiment of the invention, the manufacturing method further includes forming a second electrode pattern on the backlight surface of the semiconductor substrate, and sintering the second electrode pattern to form a back surface electrode of the solar cell.

According to an embodiment of the invention, the metal electrode material is formed on the antireflection layer by a screen printing method.

According to an embodiment of the invention, the first electrode pattern includes a plurality of bus electrodes and a plurality of finger electrodes.

According to an embodiment of the invention, the material of the first electrode pattern is selected from the group consisting of titanium, cobalt, tungsten, platinum, rhodium, ruthenium, molybdenum, chromium, palladium, gold, silver, aluminum, and alloys thereof.

According to an embodiment of the invention, the material of the first electrode pattern is a silver paste.

According to an embodiment of the invention, the material of the anti-reflection layer is nitrogen. 矽 (SiNx).

According to an embodiment of the invention, the oxide layer is silver oxide.

In accordance with an embodiment of the present invention, the method of removing an oxide layer includes dissolving an oxide layer using a reverse current process to expose an unoxidized metal electrode material.

According to an embodiment of the present invention, the above manufacturing method further includes removing at least one residual metal electrode material around the first electrode pattern by a reverse current process.

According to an embodiment of the invention, the material of the plating layer is the same as the first electrode pattern.

110, 120, 130, 140, 150‧ ‧ steps

210‧‧‧Semiconductor substrate

212‧‧‧Welcome

214‧‧‧ Backlit surface

220‧‧‧Anti-reflective layer

230a, 230b, 230c, 610a, 610b‧‧‧ first electrode pattern

230d‧‧‧ front electrode

231, 520a‧‧‧ oxide layer

310‧‧‧ plating bath

320‧‧‧ plating solution

330‧‧‧Electroplated metal parts

340‧‧‧to be plated

350‧‧‧DC power supply

510a, 510b‧‧‧metal electrode material layer

530a, 530b‧‧‧ plating

620a, 620b‧‧‧ Residual metal electrode material

+‧‧‧Anode

-‧‧‧cathode

1 is a flow chart showing the manufacture of a solar cell according to an embodiment of the present invention; and FIGS. 2A-2E are cross-sectional views showing the manufacture of a solar cell according to an embodiment of the present invention; A schematic diagram of an electroplating step according to an embodiment of the present invention; FIG. 4 is a schematic diagram of a reverse current step according to an embodiment of the present invention; and FIG. 5(a) is a microscopic cross-sectional image of a general electrode pattern. And FIG. 5(b) is a microscopic cross-sectional image of an electrode pattern according to an embodiment of the present invention; and FIG. 6(a) is a microscopic top view image of a general electrode pattern, and FIG. Figure (b) is a microscopic top view image of an electrode pattern in accordance with one embodiment of the present invention.

The invention will be described in detail by way of example and with reference to the accompanying drawings In the drawings, the shape or thickness of the embodiments may be expanded to simplify or facilitate the labeling, and the parts of the elements in the drawings will be described in the text. It will be appreciated that elements not shown or described may be in a variety of styles known to those skilled in the art.

The terminology used herein is for the purpose of describing particular embodiments and is not intended to The singular forms "a", "the", "the" and "the" It is to be understood that the term "comprises" and / or "comprising" when used in the specification is intended to mean the presence of the described features, integers, steps, operations, components and/or components, but does not exclude the presence or addition. One or more other features, integers, steps, operations, components, components, and/or groups thereof. Embodiments of the present invention are described herein with reference to cross-section illustrations of the schematic illustration of the preferred embodiments (and intermediate structures) of the invention. As such, it is contemplated that the shapes of the descriptions may be varied, for example, from variations in manufacturing techniques and/or tolerances. Therefore, the embodiments of the invention should not be construed as being limited to the particular shapes of the embodiments described herein. The shapes of the devices are not intended to limit the actual shape of the device and are not intended to limit the scope of the invention.

1 is a flow chart showing the manufacture of a solar cell according to an embodiment of the present invention. In Fig. 1, steps 110-150 illustrate various steps in the fabrication of a solar cell in accordance with an embodiment of the present invention.

In step 110, a semiconductor substrate is provided. The semiconductor substrate has a light-incident surface and a backlight surface opposite to the light-incident surface, wherein the light-incident surface has an anti-reflection layer. In step 120, a metal electrode material is formed on the anti-reflective layer to form a first electrode pattern. In an embodiment of the invention, the first electrode pattern includes a plurality of bus electrodes and a plurality of finger electrodes, and the material of the first electrode pattern is selected from the group consisting of titanium, cobalt, tungsten, platinum, rhodium, ruthenium, molybdenum, and chromium. , a group of palladium, gold, silver, aluminum and their alloys. In another embodiment of the invention, the material of the first electrode pattern is a silver paste, and the material of the anti-reflection layer is tantalum nitride (SiNx).

The first electrode pattern is then sintered, as described in step 130. In an embodiment of the invention, the manufacturing method further includes forming a second electrode pattern on the backlight surface of the semiconductor substrate, and sintering the second electrode pattern to form a back surface electrode of the solar cell. In another embodiment of the invention, the metal electrode material is formed in the antireflective layer by screen printing.

In step 140, an oxide layer formed on the surface of the metal electrode material in the sintered first electrode pattern is removed, wherein the oxide layer is silver oxide. In one embodiment of the invention, a method of removing an oxide layer includes dissolving an oxide layer using a reverse current process to expose an unoxidized metal electrode material. In another embodiment of the invention, at least one residual metal electrode material surrounding the first electrode pattern is more removable using a reverse current process.

In step 150, forming a plating layer on the metal of the removed oxide layer The electrode material is formed to form a front electrode of the solar cell. In an embodiment of the invention, the material of the plating layer is the same as the first electrode pattern.

2A-2E are cross-sectional views showing the manufacture of a solar cell according to an embodiment of the present invention. The 2A-2E drawings respectively incorporate the steps of steps 110-150 of FIG. 1 to represent various manufacturing stages of the solar cell.

In FIG. 2A, a semiconductor substrate 210 is provided. The semiconductor substrate 210 has a light-incident surface 212 and a backlight surface 214, wherein the light-incident surface 212 is opposite to the backlight surface 214. The anti-reflection layer 220 is located on the light-facing surface 212 of the semiconductor substrate 210. In an embodiment of the invention, the material of the anti-reflective layer 220 is tantalum nitride (SiNx).

In FIG. 2B, a metal electrode material is formed on the anti-reflection layer 220 to form a first electrode pattern 230a. The first electrode pattern 230a further passes through the anti-reflection layer 220 and is in contact with the semiconductor substrate 210. In an embodiment of the invention, the first electrode pattern 230a includes a plurality of bus electrodes and a plurality of finger electrodes, and the material of the first electrode pattern 230a is selected from the group consisting of titanium, cobalt, tungsten, platinum, rhodium, ruthenium, and molybdenum. a group of chromium, palladium, gold, silver, aluminum, and alloys thereof. In another embodiment of the invention, the material of the first electrode pattern 230a is a silver paste.

In FIG. 2C, the first electrode pattern 230a in FIG. 2B is sintered to form the first electrode pattern 230b. During the sintering process, an oxide layer 231 is formed on the surface of the metal electrode material of the first electrode pattern 230b, wherein the oxide layer 231 is silver oxide. In an embodiment of the invention, the manufacturing method further includes forming a second electrode pattern on the back of the semiconductor substrate On the glossy side, and sintering the second electrode pattern, a back electrode of the solar cell is formed. In another embodiment of the invention, the metal electrode material is formed in the antireflective layer by screen printing.

In FIG. 2D, the oxide layer 231 on the surface of the metal electrode material in FIG. 2B is removed to expose the unoxidized metal electrode material to form the first electrode pattern 230c. In one embodiment of the invention, the method of removing the oxide layer 231 includes dissolving the oxide layer 231 using a reverse current process. In another embodiment of the invention, at least one residual metal electrode material surrounding the first electrode pattern is more removable using a reverse current process.

In Fig. 2E, a plating layer is formed on the metal electrode material through which the oxide layer is removed to form the front electrode 230d of the solar cell. In an embodiment of the invention, the material of the plating layer is the same as that of the first electrode pattern 230a.

FIG. 3 is a schematic view showing a plating step according to an embodiment of the present invention. Figure 3 is a step of forming a plating layer in conjunction with step 150 of Figure 2E and Figure 1.

In the third drawing, the plating bath 310 contains a plating solution 320. Both the plated metal member 330 and the member to be plated 340 are immersed in the plating solution 320 and are located below the liquid level of the plating solution 320. In one embodiment of the present invention, the plated metal member 330 is a silver metal rod or a silver metal plate, the plate to be plated 340 includes the first electrode pattern 230c in FIG. 2D, and the plating solution 320 is a plating solution containing silver ions. .

When the plated metal member 330 and the member to be plated 340 are respectively connected to the anode (+) and the cathode (-) of the DC power source 350, the plated metal member 330 oxidizes to generate metal ions; and the plated member 340 reductively deposits the plating layer. In this embodiment, the metal ion is silver ion (Ag ⁺ ); and the plating layer is a silver metal (Ag) layer.

4 is a schematic diagram of a reverse current step according to an embodiment of the invention. Figure 4 is a step of removing the oxide layer in conjunction with step 140 of Figure 2 and Figure 140.

The composition of Figure 4 is similar to Figure 3. The plating bath 310 contains a plating solution 320. Both the plated metal member 330 and the member to be plated 340 are immersed in the plating solution 320 and are located below the liquid level of the plating solution 320. In one embodiment of the invention, the plated metal member 330 is a silver metal rod or a silver metal plate, and the plating solution 320 is a plating solution containing silver ions (Ag ⁺ ).

However, the difference between FIG. 4 and FIG. 3 is that the member to be plated 340 of FIG. 4 includes the first electrode pattern 230b of FIG. 2C, and the electrode connection of FIG. 4 is opposite to that of FIG. 3, that is, The aforementioned reverse current is generated. When the electroplated metal member 330 and the member to be plated 340 are respectively connected to the cathode (-) and the anode (+) of the DC power source 350, the oxide layer on the member to be plated 340 is dissolved in the plating solution 320; and the plated metal member 330 is The deposited metal layer will be reduced. In this embodiment, the reverse current is used to dissolve the oxide layer on the first electrode pattern while removing the residual metal electrode material around the first electrode pattern.

Fig. 5(a) is a microscopic cross-sectional image of a general electrode pattern, and Fig. 5(b) is a microscopic cross-sectional image of an electrode pattern according to an embodiment of the present invention.

As can be seen from Fig. 5(a), the general electrode pattern sequentially has a metal electrode material layer 510a, an oxide layer 520a, and a plating layer 530a. The electrode pattern of one embodiment of the present invention has a metal electrode material layer 510b and a plating layer 530b as shown in Fig. 5(b). Please refer to Table 1, because the oxide layer has The high sheet resistance (Rs) makes the current value (Isc) of the solar cell low and the sheet resistance value is high. Therefore, an embodiment of the present invention utilizes a reverse current process to remove an oxide layer on a metal electrode material layer, causing the plating layer to directly contact the metal electrode material layer to increase the current value and reduce the sheet resistance value of the electrode pattern.

In Table 1, compared with the general electrode pattern, the electrode pattern provided by one embodiment of the present invention has less change in current value after electroplating, and the sheet resistance value has a relatively significant decrease.

In an embodiment of the invention, a reverse current process can be used to remove residual metal electrode material around the first electrode pattern. Since a small amount of silver paste is sprayed on both sides of the first electrode pattern when the first electrode pattern is screen printed, the residual metal electrode material on both sides of the first electrode pattern can be dissolved by the reverse current process to The light shielding rate of the surface of the solar cell is reduced, and the photoelectric conversion efficiency of the solar cell is improved.

Fig. 6(a) is a microscopic top view image of a general electrode pattern; and Fig. 6(b) is a microscopic top view image of an electrode pattern according to an embodiment of the present invention. In Fig. 6(a), the two sides of the first electrode pattern 610a have a plurality of residual metal electrode materials 620a. In an embodiment of the invention, a reverse current process is utilized Not only the oxide layer lift current value in the first electrode pattern 610b but also the residual metal electrode material 620b on both sides of the first electrode pattern 610b can be removed, as shown in FIG. 6(b).

Comparing Fig. 6 (a) and (b), the first electrode pattern 610a of Fig. 6(a) has a plurality of residual metal electrode materials 620a on both sides; and the first electrode pattern 610b of Fig. 6(b) The residual metal electrode material 620b on the side is significantly less.

Although the embodiments of the present invention have been disclosed as above, it is not intended to limit the present invention, and any person skilled in the art can make some modifications and retouchings without departing from the spirit and scope of the present invention. The scope is defined as defined in the scope of the patent application.

110, 120, 130, 140, 150‧ ‧ steps

Claims (9)

A method of manufacturing a solar cell, comprising: providing a semiconductor substrate having a light-incident surface and a backlight surface opposite to the light-incident surface, wherein the light-incident surface has an anti-reflection layer; forming a metal electrode Material on the anti-reflective layer to form a first electrode pattern; sintering the first electrode pattern; dissolving in a reverse current process and removing one of the first electrode patterns formed on the surface of the metal electrode material An oxide layer is formed to expose the unoxidized metal electrode material; and a plating layer is formed on the metal electrode material from which the oxide layer is removed to form a front electrode of the solar cell. The manufacturing method of claim 1, further comprising forming a second electrode pattern on the backlight surface of the semiconductor substrate, and sintering the second electrode pattern to form a back surface electrode of the solar cell. The manufacturing method according to claim 1, wherein the metal electrode material is formed on the antireflection layer by a screen printing method. The manufacturing method of claim 1, wherein the first electrode pattern comprises a plurality of bus electrodes and a plurality of finger electrodes. The manufacturing method of claim 1, wherein the material of the first electrode pattern is selected from the group consisting of titanium, cobalt, tungsten, platinum, rhodium, ruthenium, molybdenum, chromium, palladium, gold, silver, aluminum, and alloys thereof. Group. The manufacturing method of claim 1, wherein the material of the first electrode pattern is a silver paste. The manufacturing method according to claim 1, wherein the oxide layer is silver oxide. The manufacturing method of claim 1, further comprising removing at least one residual metal electrode material around the first electrode pattern by the reverse current process. The manufacturing method of claim 1, wherein the material of the plating layer is the same as the first electrode pattern.