TWI475711B - Wet-etching machine for solar cell manufacturing process - Google Patents

Description

Solar cell manufacturing program with wet etching machine

The present invention relates to a wet etching machine for a solar cell manufacturing process, and more particularly to a wet etching machine for a solar cell manufacturing process capable of reducing the frequency of replacing an etching solution.

Wet etching is a commonly used etching technique. It is a chemical etching of a wafer by using an acid mixed solution such as a hydrofluoric acid (HF) mixed solution, which has the advantages of simple process, low etching cost, and yield (Throughput High and reliable. In order to extend the service life of the etching solution, a wet etching machine (Wet Station) used in a solar cell manufacturing process usually uses a wet etching circulation tank system having a program tank and a buffer tank structure.

Figure 1 shows a schematic of a wet etching machine for a conventional solar cell manufacturing process. As shown in FIG. 1, the solar cell manufacturing program wet etching machine 100 includes a program tank 110 and a buffer tank 120. The program slot 110 includes a processing tank 111 and an overflow tank 112. When the solar cell manufacturing process is operated by the wet etching machine 100, the twinned substrate 10 is placed in the processing bath 111, and the etching liquid etches the twinned substrate 10, thereby causing a decrease in the acid concentration of the etching liquid. At this time, the etchant in the buffer tank 120 is extracted by a pump 131, and after being pressurized by the pump 131, the etchant is supplied to the processing tank 111 of the program tank 110 to maintain the concentration of the processing tank 111. The treatment tank 111 is placed inside the overflow tank 112, and the wall surface of the overflow tank 112 is higher than the wall surface of the treatment tank 111, and overflows when the etching liquid in the treatment tank 111 is excessive (overflow S as shown in Fig. 1). The tank 111 flows into the overflow tank 112 and finally flows from the overflow tank 112 to the buffer tank 120.

When the concentration of the acid solution in the buffer tank 120 does not reach a predetermined value, the etching liquid must be replaced. When the etching solution is replaced, the solar cell manufacturing process is sometimes stopped by the wet etching machine 100, the acid solution in the buffer tank 120 is discharged by the pump 132, and the pump 133 is turned on to supply the new etching liquid into the buffer tank 120.

Generally, the etching solution in the buffer tank 120 uses nitric acid (HNO ₃ ) and hydrofluoric acid (HF), and the initial concentration is set to a concentration of HNO ₃ = 70% and HF = 49%, respectively; the initial specific gravity is HNO3 = 1.41, HF, respectively. =1.17. The amount of water (H ₂ O-Di) added to the buffer tank 120 is 175.27 L, the amount of HNO ₃ is 204.26 L, and the amount of HF is 100.47 L. Therefore, in the initial state, the concentration of each acid of the etching solution of the buffer tank 120 is HNO ₃ , respectively. = 420 g / L, HF = 120 g / L. 2A and 2B are graphs showing the relationship between the yield and the concentration of the etchant in the buffer tank, respectively, according to the prior art. As shown in Figs. 2A and 2B, when the yield is 400,000 sheets, the etching liquid must be replaced.

An object of an embodiment of the present invention is to provide a wet etching machine for a solar cell manufacturing program capable of reducing the frequency of replacing an etching solution.

According to an embodiment of the invention, a wet etching machine for a solar cell manufacturing process includes a program tank, a buffer tank, a first automatic pump, a second automatic pump, and a controller. The program slot stores an etchant for etching a plurality of twin substrates. The buffer tank stores an etchant, wherein the etchant in the buffer tank is pumped into the program tank by a pump and receives excess etchant in the program tank. The first automatic pump is connected to the buffer tank for discharging the etching liquid in the buffer tank. The second automatic pump is connected to the buffer tank for adding a new etching solution into the buffer tank. The controller is coupled to the first automatic pump and the second automatic pump for controlling the first automatic pump and the second automatic pump to control the flow rate of the new etching liquid added to the buffer tank; and the etching for discharging the buffer tank The flow rate of the liquid.

In one embodiment, the flow rate of the new etchant added to the buffer tank is substantially equal to the flow rate of the etchant that drains the buffer tank.

In an embodiment, the controller further stores a preset process parameter, and calculates a current process parameter of the wet etching machine for the solar cell manufacturing process. When the current process parameter is equal to or greater than the preset process parameter, during a predetermined circulation period. Inside, the first automatic pump and the second automatic pump are opened to a predetermined opening size.

In one embodiment, the solar cell manufacturing process further includes a flow meter connected to the first automatic pump for measuring the flow rate of the etchant discharged by the first automatic pump in the buffer tank. Preferably, the controller further receives the flow rate of the etchant discharged by the first automatic pump measured by the flow meter, and turns off the first automatic when the flow rate of the etchant discharged by the first automatic pump is greater than a preset value. Pump and second automatic pump.

In an embodiment, the controller further zeros the current process parameters and re-statistics the current process parameters.

According to an embodiment of the present invention, in the operation of the wet etching machine for the solar cell manufacturing process, a new etching liquid is added to the buffer tank and the flow rate of the old etching liquid is discharged, thereby reducing the wetness of the solar cell manufacturing process. The frequency of the etcher shutdown increases the utilization rate of the wet etching machine for the solar cell manufacturing process, thereby increasing the productivity and reducing the manufacturing cost. .

Other objects and advantages of the present invention will become apparent from the technical features disclosed herein. The above and other objects, features, and advantages of the invention will be apparent from

3 is a schematic view showing a wet etching machine for a solar cell manufacturing process according to an embodiment of the present invention. As shown in FIG. 3, in accordance with an embodiment of the present invention, a wet etching machine 200 for a solar cell manufacturing process includes a program slot 210 and a buffer tank 220. The program slot 210 includes a processing tank 211 and an overflow tank 212. When the solar cell manufacturing process is performed by the wet etching machine 200, the twinned substrate 10 is placed in the processing bath 211 to etch the twinned substrate 10. When the concentration of the etching liquid in the processing tank 211 is insufficient, the etching liquid in the buffer tank 220 is extracted by a pump 231 and supplied to the processing tank 211 to maintain the etching liquid concentration of the processing tank 211. The treatment tank 211 is placed inside the overflow tank 212, and the wall surface of the overflow tank 212 is higher than the wall surface of the treatment tank 211. When the etching liquid of the treatment tank 111 generates the overflow S, the overflow S can be caused to flow to the overflow tank 212. Then, it flows from the overflow tank 212 to the buffer tank 220.

In the present embodiment, the solar cell manufacturing program wet etching machine 200 further includes a first automatic pump 241, a second automatic pump 242, and a controller 240. The first automatic pump 241 is in communication with the buffer tank 220 to discharge the etching liquid in the buffer tank 220. The second automatic pump 242 is in communication with the buffer tank 220 to add a new etching liquid into the buffer tank 220. The controller 240 is coupled to the first automatic pump 241 and the second automatic pump 242 for controlling the opening size and the circulation period of the automatic pumps 241 and 242, and further controlling the flow rate of the etching liquid added to the buffer tank 220, and The flow rate of the etching liquid discharged from the buffer tank 220. Preferably, the flow rate of the etching liquid added to the buffer tank 220 is made substantially equal to the flow rate of the etching liquid discharged from the buffer tank 220.

4 is a schematic view showing a wet etching machine for a solar cell manufacturing process according to an embodiment of the present invention. The wet etching machine 200a for the solar cell manufacturing process of the embodiment of the present invention is similar to the wet etching machine 200 for the solar cell manufacturing process of the embodiment of Fig. 3. Therefore, the same elements are denoted by the same reference numerals, and the related description will be omitted. Only the differences between the two embodiments will be explained. In the present embodiment, the solar cell manufacturing process further includes a flow meter 244 using the wet etching machine 200a. The flow meter 244 is connected to the first automatic pump 241 for measuring the discharge amount Qs of the etchant discharged from the first automatic pump 241 in the buffer tank 220. The flow meter 244 is also coupled to the controller 240 and transmits the measured discharge amount Qs to the controller 240. When the controller 240 determines that the discharge amount Qs measured by the flow meter 244 is greater than a predetermined value, the first automatic pump 241 and the second automatic pump 242 are turned off, so that the automatic pumps 241 and 242 stop adding to the buffer tank 220 or Drain the etchant.

In the embodiment of FIG. 3, although the controller 240 can infer the addition amount and the discharge amount of the etching liquid of the buffer tank 220 according to the opening size and the circulation period of the automatic pumps 241 and 242, the flow accuracy of the method is less accurate. . In the embodiment of FIG. 4, a flow meter 244 is additionally provided, which can accurately calculate the addition amount and the discharge amount of the etching liquid of the buffer tank 220. In an embodiment, a flow meter (not shown) may be further added to connect the flow meter to the second automatic pump 242 for measuring the flow rate through the second automatic pump 242.

Finally, when the concentration of the acid solution in the buffer tank 220 does not reach a predetermined value, the acid solution in the buffer tank 220 can be discharged by the pump 232 to feed the new etching liquid into the buffer tank 220.

6 is a flow chart showing an automatic acid removal method of a controller for a wet etching machine for a solar cell manufacturing process according to an embodiment of the present invention. As shown in FIG. 6, in an embodiment, the automatic acid removal method of the controller 240 includes the following steps.

Step S02: Store a preset process parameter in the controller 240. The preset process parameter may be a preset operation time of the wet etching machine for the solar cell manufacturing process or a preset number of processed wafers (wafer).

Step S04: Counting the current process parameters of the wet etching machine for the solar cell manufacturing process, that is, counting the current operating time or the number of processed wafers of the wet etching machine for the solar cell manufacturing process.

Step S06: Comparing the preset process parameters with the current process parameters. When the current process parameters are equal to or greater than the preset process parameters, the first automatic pump 241 and the second automatic pump 242 are opened to a predetermined schedule during a predetermined circulation period. The opening is sized to add and discharge an etchant to the buffer tank 220, and then the next step is performed. When the current process parameter is less than the preset process parameter, step S04 is performed to continuously calculate the current process parameters of the wet etching machine for the solar cell manufacturing process.

Step S08: receiving the flow rate of the etching liquid passing through the first automatic pump 241 or the second automatic pump 242 measured by a flow meter, and the flow rate of the etching liquid passing through the first automatic pump 241 and the second automatic pump 242, When the value is greater than a predetermined value, the first automatic pump 241 and the second automatic pump 242 are turned off.

Step S10: After zeroing the foregoing current process parameters, step S04 is performed, and the current process parameters are again re-stated.

5A and 5B are graphs showing the relationship between the yield and the concentration of the etchant in the buffer tank, respectively, in accordance with an embodiment of the present invention. More specifically, the etching solution in the buffer tank 220 uses nitric acid (HNO ₃ ) and hydrofluoric acid (HF), and the initial concentration is set to a concentration of HNO ₃ = 70% and HF = 49%, respectively; the initial specific gravity is HNO3, respectively. = 1.41, HF = 1.17. In the initial state, the amount of water (H ₂ O-Di) in the buffer tank 220 is 175.27 L, the amount of HNO ₃ is 204.26 L, and the amount of HF is 100.47 L. The inventor conducts a test experiment, automatically discharges the etching liquid in the 10L buffer tank 220 every day, and adds 10L of new etching liquid to the buffer tank 220. The variation result of the concentration of nitric acid and hydrofluoric acid in the buffer tank 220 is as shown in FIG. 5A. And the curve shown in 5B. Referring to FIGS. 5A and 5B, according to an embodiment of the present invention, when the yield is 400,000 pieces, the concentration of nitric acid (HNO ₃ ) and hydrofluoric acid (HF) in the buffer tank 220 is maintained above a certain value. It is only necessary to replace the etching liquid in the buffer tank 220 when the output is 800,000 pieces. Therefore, the service life of the etching liquid in the buffer tank 220 is prolonged, and the timing of replacing the etching liquid is reduced.

According to an embodiment of the present invention, in the operation of the wet etching machine for the solar cell manufacturing process, a new etching liquid is added to the buffer tank and the flow rate of the old etching liquid is discharged, thereby reducing the solar cell manufacturing procedure. The frequency of the wet etching machine shutdown increases the utilization rate of the wet etching machine for the solar cell manufacturing process, thereby increasing the production capacity and reducing the manufacturing cost.

While the present invention has been described in its preferred embodiments, the present invention is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application. In addition, any of the objects or advantages or features of the present invention are not required to be achieved by any embodiment or application of the invention. In addition, the abstract sections and headings are only used to assist in the search of patent documents and are not intended to limit the scope of the invention.

10. . . Twin crystal substrate

100. . . Solar cell manufacturing program with wet etching machine

110. . . Program slot

111. . . Processing tank

112. . . Overflow trough

120. . . Buffer tank

131~133. . . Pump

200. . . Solar cell manufacturing program with wet etching machine

200a. . . Solar cell manufacturing program with wet etching machine

210. . . Program slot

211. . . Processing tank

212. . . Overflow trough

220. . . Buffer tank

231~232. . . Pump

240. . . Controller

241. . . First automatic pump

242. . . Second automatic pump

244. . . Flow meter

Figure 1 shows a schematic of a wet etching machine for a conventional solar cell manufacturing process.

2A and 2B are graphs showing the relationship between the yield and the concentration of the etchant in the buffer tank, respectively, according to the prior art.

3 is a schematic view showing a wet etching machine for a solar cell manufacturing process according to an embodiment of the present invention.

4 is a schematic view showing a wet etching machine for a solar cell manufacturing process according to an embodiment of the present invention.

5A and 5B are graphs showing the relationship between the yield and the concentration of the etchant in the buffer tank, respectively, in accordance with an embodiment of the present invention.

6 is a flow chart showing an automatic acid removal method of a controller for a wet etching machine for a solar cell manufacturing process according to an embodiment of the present invention.

200. . . Solar cell manufacturing program with wet etching machine

210. . . Program slot

211. . . Processing tank

212. . . Overflow trough

220. . . Buffer tank

231~232. . . Pump

240. . . Controller

241. . . First automatic pump

242. . . Second automatic pump

Claims (9)

A solar cell manufacturing program using a wet etching machine, comprising: a program tank, storing an etching liquid for etching a plurality of twin crystal substrates; and a buffer tank storing the etching liquid, wherein the buffering liquid The etchant is pumped into the program tank by a pump, and receives the etchant in the program tank; a first automatic pump is connected to the buffer tank for discharging the etchant in the buffer tank; a second automatic pump connected to the buffer tank for adding a new etching liquid into the buffer tank; and a controller coupled to the first automatic pump and the second automatic pump for controlling the first An automatic pump and the second automatic pump for controlling a flow rate of the new etching liquid added to the buffer tank; and a flow rate of the etching liquid discharged from the buffer tank, wherein the program tank comprises: a processing tank for Receiving the etching liquid from the buffer tank; and an overflow tank for receiving the excess etching liquid of the processing tank and communicating with the buffer tank to flow the excess etching liquid to the buffer tank. The solar cell manufacturing process as described in claim 1 is wet. The etching machine, wherein the etching solution of the buffer tank comprises a nitric acid and a hydrofluoric acid, the initial concentrations of the nitric acid and the hydrofluoric acid are 70% and 49%, respectively; the initial specific gravity of the nitric acid and the hydrofluoric acid are respectively 1.41 and 1.17, and in the initial state, the buffer tank contains 175.27 L of water, 204.26 L of the nitric acid, and 100.47 L of the hydrofluoric acid, and the flow rate of the new etching solution added to the buffer tank; The flow rate of the etching liquid discharged from the buffer tank was 10 L. A wet etching machine for a solar cell manufacturing process according to claim 1, wherein a flow rate of the new etching liquid added to the buffer tank is substantially equal to a flow rate of the etching liquid that discharges the buffer tank. The wet etching machine for manufacturing a solar cell according to claim 1, wherein the controller further stores a preset process parameter, and the solar cell manufacturing program uses the current process parameters of the wet etching machine. When the current process parameter is equal to or greater than the preset process parameter, the first automatic pump and the second automatic pump are opened to a predetermined opening size during a predetermined circulation period. The wet etching machine for solar cell manufacturing process according to claim 4, further comprising a flow meter connected to the first automatic pump for measuring the discharge of the buffer tank by the first automatic pump The flow rate of the etchant. A wet etching machine for manufacturing a solar cell according to claim 5, wherein the controller further receives the first measured by the flow meter. The flow rate of the etchant discharged from the automatic pump turns off the first automatic pump and the second automatic pump when the flow rate of the etchant discharged by the first automatic pump is greater than a predetermined value. The wet etching machine for solar cell manufacturing process according to claim 6, wherein the controller further resets the current process parameter to zero and re-counts the current process parameter again. The wet etching machine for solar cell manufacturing process according to claim 7, wherein the preset process parameter and the current process parameter comprise an operation time of the wet etching machine for the solar cell manufacturing program and a Process at least one of the number of slices. The wet etching machine for manufacturing a solar cell according to claim 8 , wherein the etchant of the buffer tank comprises a nitric acid and a hydrofluoric acid, and an initial concentration of the nitric acid and the hydrofluoric acid is 70% respectively. And 49%; the initial specific gravity of the nitric acid and the hydrofluoric acid are 1.41 and 1.17, respectively, and in the initial state, the buffer tank comprises 175.27 L of water, 204.26 L of the nitric acid, and 100.47 L of the hydrofluoric acid, and The flow rate of the new etching liquid added to the buffer tank; and the flow rate of the etching liquid discharged from the buffer tank is 10L.