TWI382558B - Method of fabricating a solar cell - Google Patents

Description

Solar cell panel manufacturing method

The present invention relates to a method of fabricating a solar cell panel, and more particularly to a method of fabricating a back electrode of a solar cell panel.

At present, the fabrication of a solar cell is generally performed as shown in US Pat. No. 6,982,218, the process of which is to deposit a passivation layer on the back surface of a semiconductor wafer (ie, the backlight surface), and then form a passivation layer. An aluminum metal layer is on the passivation layer, and finally the laser beam of the laser sintering technique is used to irradiate the metal layer through a grid having a predetermined pattern (such as a line, a linear or a dot pattern), so that the metal layer is heated and melted. The eutectic structure is formed by the passivation layer and the wafer to form the back electrode of the desired pattern, and at the same time, the passivation of the back side of the wafer is completed, thereby reducing the rate of the backside composite carrier.

However, the cost of obtaining a laser sintering apparatus and using a laser sintering apparatus for sintering is quite expensive, and the use of a laser beam for laser sintering of a metal layer also has a risk of causing damage to the wafer. In this way, if a different technical method can be provided, the cost of acquisition can be reduced, and the original effect of using the laser sintering technology can be maintained, which has become an issue that the industry is eager to improve.

In view of the above, an object of the present invention is to provide a method for fabricating a solar cell panel, which can replace the laser sintering technology, can greatly reduce the manufacturing cost, achieve the passivation treatment on the back side of the wafer, and maintain the original laser sintering technology. Reduce the back composite carrier rate and enhance the long-band frequency response.

Another object of the present invention is to provide a method of fabricating a solar cell panel that reduces the risk of damage to the wafer.

According to the above object of the present invention, a method for fabricating a solar cell panel is provided, wherein the step includes providing a semiconductor wafer substrate, and an emitter layer and an anti-reflection layer are sequentially disposed on a light-incident surface of the semiconductor wafer substrate. And an oxide layer on the backlight surface, and then coating an etchant on the oxide layer according to a predetermined pattern, so that the etchant on the oxide layer generates a recess deep into the backlight surface of the semiconductor wafer substrate, and then, Forming a metal layer on the oxide layer, in particular filling the recessed portion with the metal layer, and heating the unfinished solar cell panel to a first temperature, so that the metal layer in the recess portion is co-produced with the semiconductor wafer substrate The crystal structure becomes a back electrode.

The structure of one of the first features described herein below in the present specification covers or lies above a second feature, which may include embodiments in which the first and second features are in direct contact, but may also include An embodiment in which additional features are interposed between the first and second features means that the first and second features are not in direct contact.

The invention is a manufacturing method of a solar cell panel. The following is a manufacturing step of providing an embodiment to further clarify the technical features of the present invention:

Step (201) provides a semiconductor wafer substrate 11 (ie, a P-type layer or an N-type layer), and two corresponding surfaces of the semiconductor wafer substrate 11 respectively have a light-incident surface 111 for facing external light, and a The semiconductor wafer substrate 11 can be a single crystal monocrystalline or multicrystalline wafer facing away from the backlight surface 112 of the mating surface 111.

Step (202) forming a first oxide layer 121 and a second oxide layer 122 on the light-incident surface 111 and the backlight surface 112 of the semiconductor wafer substrate 11, wherein the formation of the second oxide layer 122 can be regarded as a passivation layer. The backlight surface 112 of the semiconductor wafer substrate 11 is made to have an effect of achieving passivation. The formation of such an oxide layer can be formed by wet oxidation (Wet Oxidation), dry oxidation (Dryt Oxidation), and plasma enhanced chemical vapor deposition (PECVD).

Step (203) removes the first oxide layer 121 on the light-incident surface 111 of the semiconductor wafer substrate 11 by wet chemical technique (Wet-Chemical).

Step (204) performs a diffusion process on the light-incident surface 111 of the semiconductor wafer substrate 11, wherein an emitter layer 13 (ie, a P-type layer or an N-type opposite to the semiconductor wafer substrate 11) is formed. a layer, for example, a nitride layer (N+layer) on the light-incident surface 111 of the semiconductor wafer substrate 11, and then removing the emitter layer 13 by a Phospho-Silicate Glass etching (PGE) technique. One layer of Phospho-Silicate Glass (PSG).

Step (205) forming an anti-reflection layer 14 on the emitter layer 13, wherein the anti-reflection layer 14, for example, may be formed on the emitter layer 13 by Plasma Enhanced Chemical Vapor Deposition (PECVD), and anti-reflection The material of layer 14 can be, for example, a nitride or an oxide.

Step (206) applying an etchant 15 to the second oxide layer 122 through a grid having a predetermined pattern, so that the etchant 15 is etched toward the light-emitting surface 111 of the semiconductor wafer substrate 11 along the contour of the predetermined pattern. Until the one or more recesses (or holes) 151 are formed on the second oxide layer 122, the recesses 151 pass through the second oxide layer 122 to expose the backlight surface 112 of the semiconductor wafer substrate 11, wherein the etching The composition of the glue 15 is ammonium hydrogen fluoride (Ammonium hydrogen difluoride) and formic acid (Formic acid), and the etching paste 15 can be etched according to the time range of the oxide layer material and thickness (for example, 20 to 60 seconds), and the grid is Anti-erosion material.

Of course, after the recessed portion 151 is formed, the recessed portion 151 of the unfinished solar cell panel 10 and the remaining compound on the adjacent position can be cleaned by DI water.

Step (207) prints a silver paste onto the anti-reflection layer 14 according to another predetermined pattern by using a screen printing method, and passes the unfinished solar cell panel 10 through a rapid sintering furnace for a temperature (about 700 to 900 degrees). The sintering process is heated by acceptance so that another predetermined pattern of silver paste can penetrate the anti-reflection layer 14 and form a eutectic structure with the light-facing surface 111 of the semiconductor wafer substrate 11 to form an alloy 161 of silver telluride. It becomes the front electrode 16 of the solar cell panel 10.

Step (208) forming a metal layer 17 on the second oxide layer 122 by sputtering, evaporation, or deposition, and the metal layer 17 is covered or entirely over a large area. The metal oxide layer 17 is filled with the recessed portion 151, and the metal layer 17 may be, for example, a metal containing aluminum, titanium or copper.

Step (209), the unfinished solar cell panel 10 is subjected to annealing/tempering or rapid thermal processing (RTP), and heated by another temperature (about 350 to 400 degrees). The metal layer 17 in the depressed portion 151 is caused to have a eutectic structure with the semiconductor wafer substrate 11, and an alloy 171 of a germanide metal is formed to form a back surface electrode of the solar cell panel 10.

Step (210) performs edge isolation processing on the emitter layer 13 to insulate the emitter layer 13 from the outside.

In this way, the solar cell panel 10 can complete the back electrode without using high-cost laser sintering technology, and can still achieve passivation on the back side of the wafer, and can reduce the effect of the back composite carrier rate and enhance the length. Band frequency response.

It is worth mentioning that the process of sintering the silver paste on the anti-reflective layer 14 in step (207) may also be followed by drying the silver paste, and then co-operating with the unfinished solar panel 10 at step (209). Heat up.

Although the present invention has been described above in terms of a preferred embodiment, it is not intended to limit the scope of the present invention, and it is possible to make various changes without departing from the spirit and scope of the invention. The scope of protection of the present invention is therefore defined by the scope of the appended claims.

10. . . Solar panel

11. . . Semiconductor wafer substrate

111. . . Bright side

112. . . Back surface

121. . . First oxide layer

122. . . Second oxide layer

13. . . Emitter layer

14. . . Antireflection layer

15. . . Etching glue

151. . . Depression

16. . . Front electrode

161, 171. . . alloy

17. . . Metal layer

step. . . 201-210

The above and other objects, features, advantages and embodiments of the present invention will become more apparent and understood.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart showing a preferred embodiment of the present invention.

2A-21 is a schematic structural view showing the flow shown in FIG. 1.

step. . . 201-210

Claims (10)

A method for fabricating a solar cell panel, comprising: providing a semiconductor wafer substrate, wherein the semiconductor wafer substrate has a light-incident surface and a backlight surface, the emitter surface sequentially having an emitter layer and an anti-reflection a layer having an oxide layer on the backlight surface; coating an etchant on the oxide layer, the etchant etching the oxide layer in a time range of 20 to 60 seconds to generate a depressed portion on the oxide layer Wherein the etching paste comprises ammonium hydrogen fluoride and formic acid; forming a metal layer on the oxide layer, and the metal layer fills the depressed portion; and heating the solar cell panel to make the metal layer and the semiconductor crystal in the depressed portion The circular substrate produces a eutectic structure that forms a back electrode. The manufacturing method of claim 1, wherein the oxide layer is a passivation layer. The manufacturing method of claim 1, wherein the step of providing the semiconductor wafer substrate comprises the steps of: forming an oxide layer on the light-emitting surface of the semiconductor wafer substrate and the backlight surface, respectively. Removing the oxide layer of the semiconductor wafer substrate on the light-facing surface by a wet chemical process; forming a surface of the emitter on the light-emitting surface of the semiconductor wafer substrate by using a diffusion process; and utilizing an electricity Slurry-assisted chemical deposition to form the anti-reflective layer On the emitter layer. The production method according to claim 3, wherein the oxide layer is formed by a wet oxidation, a dry oxidation or a plasma-assisted chemical deposition. The manufacturing method of claim 1, wherein the step of coating the etchant on the oxide layer further comprises applying a etchant to the oxide layer in combination with a grid having a predetermined pattern. The recess portion is deep to the backlight surface of the semiconductor wafer substrate, and the backlight surface of the semiconductor wafer substrate is exposed. The manufacturing method of claim 1, wherein the metal layer is formed on the oxide layer by sputtering, evaporation or deposition. The manufacturing method of claim 6, wherein the metal layer is completely covered on the oxide layer. The production method of claim 7, wherein the metal layer contains aluminum, titanium or copper. The manufacturing method according to claim 1, wherein in the step of heating the solar cell panel, the solar cell panel is annealed by a first temperature range. The manufacturing method of claim 9, wherein the step of coating the etchant on the oxide layer and the step of forming the metal layer on the oxide layer further comprises: printing by screen printing a silver paste to the anti-reflective layer; the solar cell panel is heated by a rapid sintering furnace for a second temperature range, wherein the second temperature is higher than the first temperature; and the silver paste penetrates the anti-reflection And forming a eutectic structure with the semiconductor wafer substrate to form a front electrode of the solar cell panel.