JP3967089B2 - Substrate screening apparatus and substrate screening method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a substrate screening apparatus and a substrate screening method, and more particularly to a substrate screening apparatus and a substrate screening method for excluding a substrate that is likely to cause cracks when processing the substrate in advance. is there.
[0002]
[Prior art]
A process of forming a solar cell as a conventional technique will be described. First, by slicing a silicon single crystal in an ingot, a P-type silicon substrate 1 having a predetermined thickness of 0.3 mm is formed as shown in FIG. Next, as shown in FIG. 14, by performing appropriate etching on one surface of the silicon substrate 1, minute irregularities 21 for reducing the reflectance are formed. Thereafter, n-type impurities are diffused into the silicon substrate 1.
[0003]
Next, as shown in FIG. 15, an antireflection film 22 for reducing the reflectance is formed on the silicon substrate 1 so as to cover the unevenness 21. Next, the back electrode 24 is formed on the other surface of the silicon substrate 1, and the surface electrode 23 is formed on one surface.
[0004]
Then, a solar cell is formed by producing a module (not shown) by combining the silicon substrate 1 on which the surface electrode 22 and the back electrode 24 are formed. In this way, the solar battery cell is completed.
[0005]
[Problems to be solved by the invention]
As described above, in the manufacture of solar cells, the silicon substrate surface is subjected to a predetermined treatment such as forming an electrode or forming an antireflection film. In particular, when the electrode is formed, the silicon substrate may warp due to the difference in linear expansion coefficient between the electrode material and the silicon substrate.
[0006]
This will be described. The electrode is formed by the following three steps. That is, first, aluminum and silver electrodes are printed on the surface of a silicon substrate and dried. Next, the electrode is fired. Thereafter, the solder is dipped.
[0007]
As shown in FIG. 16, an electrode 24 made of silver 25 and aluminum 26 is formed on the back surface 1b of the silicon substrate 1 after the electrodes have been baked. On the other hand, as shown in FIG. 17, an electrode 23 made of silver 27 is formed on the surface 1 a of the silicon substrate 1.
[0008]
Here, the linear expansion coefficient of the silicon substrate 1 and the linear expansion coefficient of the electrode 24 of the aluminum 26 occupying most of the back surface of the silicon substrate 1 are different by one digit (the linear expansion coefficient of aluminum is high). Therefore, as shown in FIG. 18, when the electrode 24 is baked, the silicon substrate 1 warps so that the back surface 1b of the silicon substrate 1 becomes convex due to the bimetal effect.
[0009]
As a result, bending stress is generated in the silicon substrate 1. In the case of a silicon substrate originally having a residual stress or a silicon substrate having a defect such as a microcrack as a silicon substrate, a crack grows due to the generated bending stress, and in some cases, the silicon substrate breaks. It may be lost or chipped.
[0010]
In addition, the cracked silicon substrate is eventually removed as a defective product due to further growth of cracks in a later process.
[0011]
As a result, there is a problem that processing for such a silicon substrate is wasted.
[0012]
The present invention has been made to solve the above-described problems, and one object is to provide a substrate that may be cracked or chipped when the substrate is subjected to a predetermined treatment before the substrate is put into the production line. It is to provide a substrate screening apparatus for removing in advance, and another object is to provide a method for screening such a substrate.
[0013]
[Means for Solving the Problems]
  A substrate screening apparatus according to one aspect of the present invention eliminates in advance a substrate that may be damaged by a stress generated by a predetermined process performed on the substrate in the production line before the substrate is put into the production line. This is a substrate screening apparatus for providing a stress applying means, a vibrating means, and a detecting means. The stress applying means applies substantially the same stress to the substrate as that applied to the substrate during a predetermined process.A strain generating mold portion having a concave portion corresponding to the shape of the warp of the substrate caused by the stress applied to the substrate during a predetermined process, and a substrate pressing portion for pressing the substrate against the concave portion.. The vibrating means applies vibration to the substrate to which the stress is applied by the stress applying means. The detection means captures a sound generated by the vibration of the substrate by the vibration means, and detects whether the substrate is damaged based on the captured sound signal.
[0014]
  According to this configuration,First,By stress applying means,By pressing the substrate against the concave part, the substrate deforms along the concave part,Stress that is substantially the same as the stress generated by a given process on the substrate in the production lineButPre-attached to the boardWill be.AndA substrate to which such stress is appliedBy vibration means and detection means,A substrate with or without damage such as cracksInCan be distinguished. As a result, it is possible to eliminate a substrate that may be damaged such as a crack during a predetermined process in the production line before putting such a substrate in the production line, thereby eliminating waste in the process of the production line. be able to.
[0015]
  SpecificallyThe concave portion of the strain generating mold part is a predetermined treatment in the difference in thermal expansion coefficient between the electrode material and the silicon substrate when a heat treatment for forming the electrode is performed in the manufacture of the solar cell using the silicon substrate. With a concave profile corresponding to the shape of the silicon substrate warped with the resulting stressPreferably it is.
[0016]
  ThisIn the production of solar cells, silicon substrates that may cause damage such as cracks due to heat treatment when forming electrodes can be eliminated before putting such silicon substrates into the production line. Waste in processing can be eliminated.
[0017]
The substrate pressing portion preferably presses the substrate against the concave portion of the strain generating mold portion using the pressure of gas.
[0018]
Thereby, the whole board | substrate can be pressed on a concave part substantially uniformly.
In order to use such a gas pressure, the substrate pressing portion is opposed to the concave portion of the strain generating mold portion, and includes a pressing jig provided with a gas inlet, a pressing jig, and the strain generating mold portion. And a flexible sheet member for forming a closed space into which gas is sent to and from the holding jig.
[0019]
In this case, the pressure of the gas sent into the closed space acts on the substrate via the sheet member.
[0020]
Moreover, it is preferable that the vibration means includes means for hitting the substrate with an impulse hammer.
[0021]
As a result, the substrate can be struck with a substantially constant excitation force.
The detection means includes means for obtaining a sound pressure waveform from the captured sound signal and detecting the presence or absence of damage to the substrate based on the attenuation pattern of the sound pressure waveform in a specific frequency region caused by the crack. It is preferable.
[0022]
Thereby, when vibration for a certain time is recognized in the sound pressure waveform in the specific frequency region, it can be determined that the substrate is cracked, and such a substrate can be easily eliminated.
[0023]
Alternatively, the excitation means preferably includes means for vibrating the substrate while changing the frequency by the signal generator.
[0024]
In this case, continuous excitation can be performed while changing the frequency in one excitation, so that the substrate can be identified earlier.
[0025]
The detecting means preferably includes means for obtaining a power spectrum from the captured sound signal and detecting the presence or absence of damage to the substrate based on the level of the power spectrum in the specific frequency domain caused by the crack. .
[0026]
As a result, when the sound level is high in a frequency range above a specific frequency, it can be determined that a crack has occurred in the substrate, and such a substrate can be easily eliminated.
[0027]
  According to another aspect of the present invention, there is provided a substrate screening method that eliminates in advance a substrate that may be damaged by a stress caused by a predetermined process performed on the substrate in the production line before putting the substrate in the production line. This is a substrate screening method for providing a stress adding step, a vibrating step, and a detecting step. In the stress application process,The substrate is pressed against the concave portion corresponding to the shape of the warp of the substrate caused by the stress applied to the substrate during a predetermined treatment, and theA stress is applied to the substrate that is substantially the same as the stress experienced by the substrate during a given process. In the vibration process, vibration is applied to the substrate to which the stress is applied in the stress application process. In the detection step, a sound generated by the vibration of the substrate in the vibration step is captured, and the presence or absence of damage to the substrate is detected based on the captured sound signal.
[0028]
  According to this method,First,By the stress application process,By pressing the substrate against the concave part, the substrate deforms along the concave part,Stress that is substantially the same as the stress generated by a given process on the substrate in the production lineButPre-attached to the boardWill be.AndA substrate to which such stress is appliedBy the excitation process and detection process,A substrate with or without damage such as cracksInCan be distinguished. As a result, it is possible to eliminate a substrate that may be damaged such as a crack during a predetermined process in the production line before putting such a substrate in the production line, thereby eliminating waste in the process of the production line. be able to.
[0029]
In the stress applying step, it is preferable to apply stress to the substrate by gas pressure.
[0030]
Thereby, the whole board | substrate can be pressed on a concave part substantially uniformly, and predetermined stress can be easily added to a board | substrate.
[0031]
In the excitation process, the substrate is hit with an impulse hammer, and in the detection process, a sound pressure waveform is obtained from the captured sound signal, and the substrate is based on the attenuation pattern of the sound pressure waveform in a specific frequency domain caused by the crack. It is preferable to detect the presence or absence of damage.
[0032]
Thereby, when vibration for a certain time is recognized in the sound pressure waveform in the specific frequency region, it can be determined that the substrate is cracked, and such a substrate can be easily eliminated.
[0033]
Alternatively, in the vibration process, the substrate is vibrated while changing the frequency by a signal generator, and in the detection process, a power spectrum is obtained from the captured sound signal, and the power spectrum level in a specific frequency region caused by the crack is obtained. It is preferable to detect the presence or absence of damage to the substrate based on this.
[0034]
As a result, when the sound level is high in a frequency range above a specific frequency, it can be determined that a crack has occurred in the substrate, and such a substrate can be easily eliminated.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
A substrate screening apparatus and a screening method using the same according to Embodiment 1 of the present invention will be described. First, FIG. 1 shows a block diagram of the substrate screening apparatus. As shown in FIG. 1, the substrate screening apparatus includes a stress applying unit 13, a microcrack detecting unit 14, and a good / defective product sorting unit 15.
[0036]
The stress applying means 13 applies a predetermined stress to the unprocessed silicon substrate before being processed. The microcrack detection means 14 gives an impact to the silicon substrate after the stress is applied, and detects the presence or absence of damage to the substrate by capturing the sound generated by the silicon substrate. The non-defective product / defective product sorting means 15 sorts the silicon substrates based on the information obtained by the microcrack detection means 14.
[0037]
Next, a substrate screening method using the substrate screening apparatus will be specifically described. As shown in FIG. 2, first, a strain profile generation type 2 is prepared in advance. The silicon substrate 1 is placed on the strain profile generation mold 2.
[0038]
The strain profile generation mold 2 is provided with a concave profile portion 2a that substantially matches the shape (profile) of the silicon substrate warped with a stress caused by a predetermined process. In this case, for example, the concave profile portion 2a corresponding to the shape of the silicon substrate warped with the stress generated when the electrode described in the section of the prior art is fired is provided.
[0039]
Next, as shown in FIG. 3, for example, a polyethylene sheet 3 is covered so as to cover the strain profile generation mold 2 on which the silicon substrate is placed. Next, as shown in FIG. 4, a holding jig 4 having a recess 4a is prepared. A port 5 for feeding dry air is formed near the center of the concave portion 4a of the pressing jig 4.
[0040]
Next, as shown in FIG. 5, the holding jig 4 is placed on the strain profile generating mold 2 so that the concave portion 4a of the pressing jig 4 faces the strain profile generating mold 2 on which the silicon substrate 1 is placed. To do.
[0041]
Next, as shown in FIG. 6, the pressing jig 4 is firmly pressed against the strain profile generation mold 2, and the outer peripheral portion of the pressing jig 4 is brought into close contact with the polyethylene sheet 3. Thereby, the recessed part 4a of the pressing jig 4 becomes an airtight closed space. Dry air 7 is sent into the closed space from a pipe 6 attached to the opening 5 of the holding jig 4.
[0042]
When the dry air 7 is fed into the closed space, the silicon substrate 1 receives the pressure of the dry air through the polyethylene sheet 3 and is pressed against the strain profile generation mold 2. When the silicon substrate 1 is pressed against the strain profile generation mold 2, the silicon substrate 1 is deformed along the concave profile portion 2 a of the strain profile generation mold 2. As a result, the silicon substrate 1 is subjected to substantially the same stress as the stress corresponding to the warp of the silicon substrate when a predetermined treatment is performed.
[0043]
Thereafter, the supply of dry air is stopped, the holding jig 4 and the polyethylene sheet 3 are removed, and the silicon substrate 1 is taken out from the strain profile generation mold 2.
[0044]
In the case of a silicon substrate originally having defects such as residual stress and microcracks, the crack is grown on the silicon substrate by applying this stress. On the other hand, a silicon substrate that does not have a defect is not damaged by applying this stress.
[0045]
Next, as shown in FIG. 7, the silicon substrate 1 is placed on a substrate support jig 9. Then, the vicinity of the center of the silicon substrate 1 is hit with an impulse hammer 8 and the generated sound is captured with the microphone 10. The impulse hammer is a hammer with a built-in sensor for detecting the excitation force, and can strike the silicon substrate 1 with a constant excitation force.
[0046]
The sound pressure waveform data of the sound captured by the microphone 10 are shown in FIGS. 8 and 9, respectively. FIGS. 8A, 8C, and 8E are sound pressure waveforms in the case of a silicon substrate (OK product) in which no cracks are generated. FIGS. 8B, 8D, and 8F are It is the processing waveform which performed the filter process (3.5 KHz high pass filter) about each.
[0047]
FIGS. 9A, 9C and 9E are sound pressure waveforms in the case of a silicon substrate (NG product) in which cracks are generated. FIGS. 9B, 9D and 9F are It is the processing waveform which performed the same filter process about each.
[0048]
In particular, when FIG. 8B, FIG. 8D, and FIG. 9F are compared with FIG. 9B, FIG. 8D, and FIG. It can be seen that the amplitude after vibration is larger than that of the substrate, and the vibration continues for a certain time.
[0049]
This is because, in the case of a silicon substrate (OK product) in which cracks do not occur, the amplitude in the vicinity of the resonance frequency is large due to vibration, and the high frequency region component of 3.5 KHz or more is small. In the case of a silicon substrate (NG product) in which a high frequency band component is generated due to cracks, it is considered that the high frequency region component is relatively large. It is thought that the vibration of time is recognized.
[0050]
In this way, the detected sound pressure waveform is processed by a computer, for example, so that a silicon substrate (OK product) in which no crack is generated can be easily distinguished from a silicon substrate (NG product) in which a crack is generated. Can do.
[0051]
By this determination, a silicon substrate (NG product) in which cracks are generated can be removed in advance, and only a silicon substrate (OK product) in which cracks are not generated can be sent to the production line.
[0052]
As described above, according to the present substrate screening apparatus, the stress applying means 13 can apply in advance to the substrate substantially the same stress as that generated by a predetermined process applied to the substrate in the production line. And the board | substrate with which damages, such as a crack, have arisen with respect to the board | substrate with the vibration means 14 and the microcrack detection means 15 can be distinguished.
[0053]
As a result, for example, a substrate that may cause damage such as cracks during a predetermined process in a production line for producing solar cells can be eliminated before the substrate is put into the production line. Waste in line processing can be eliminated.
[0054]
In addition, the polyethylene sheet 3 was mentioned as an example as a sheet | seat which covers the silicon substrate 1 mounted in the distortion profile production | generation type | mold 2, and is pinched | interposed between the distortion profile production | generation type | mold 2 and the pressing jig 4. FIG. As this sheet, any sheet having flexibility and airtightness may be used. For example, a polycarbonate sheet can also be applied.
[0055]
In addition, dry air is used as an example of the gas sent into the concave portion of the holding jig 4. As this gas, in addition to dry air, for example, nitrogen (N₂An inert gas such as) may be applied.
[0056]
Embodiment 2
A substrate screening apparatus and a screening method using the same according to Embodiment 2 of the present invention will be described. Here, a case will be described in which the silicon substrate after the stress is applied by the stress applying means described above is continuously vibrated while changing the frequency.
[0057]
As shown in FIG. 10, the four corners of the silicon substrate 1 to which stress is applied are fixed on the vibration table 11 by clamps 11a. Next, the silicon substrate 1 is vibrated as indicated by an arrow 12 while changing the frequency by a signal generator (not shown) built in the vibration table 11. Sound generated by the vibration of the silicon substrate 1 is captured by the microphone 10.
[0058]
The data of the power spectrum of the sound captured by the microphone 10 are shown in FIGS. 11 and 12, respectively. The power spectrum is obtained by analyzing the frequency component of the sound pressure waveform for a certain time from the sound pressure waveform on the time axis, and converting this to the frequency axis to calculate the sound level.
[0059]
FIGS. 11A, 11B, and 11C are power spectra in the case of a silicon substrate (OK product) in which no crack is generated, and FIGS. 12A, 12B, and 12C are cracks. It is a power spectrum in the case of the silicon substrate (NG product) in which the above occurs.
[0060]
When comparing FIGS. 11A, 11B, and 11C with FIGS. 12A, 12B, and 12C, in the case of a silicon substrate (NG product) in which cracks are generated, It can be seen that the sound level is higher in the frequency range of 3.5 KHz or higher than that of the non-silicon substrate (OK product).
[0061]
This is because, as described above, in the case of a silicon substrate (NG product) in which a crack has occurred, the high frequency region component becomes relatively large due to the presence of a plurality of resonance frequencies due to the crack. Conceivable.
[0062]
In this way, the detected power spectrum data is arithmetically processed by a computer, for example, so that a silicon substrate (OK product) in which no crack is generated and a silicon substrate (NG product) in which a crack is generated are easily identified. be able to.
[0063]
By this determination, a silicon substrate (NG product) in which cracks are generated can be removed in advance, and only a silicon substrate (OK product) in which cracks are not generated can be sent to the production line.
[0064]
In particular, according to the present substrate screening apparatus, power spectrum data can be obtained by a single vibration of the silicon substrate 1 and the silicon substrate can be inspected at a higher speed than the above-described substrate screening apparatus. it can.
[0065]
In addition, in the case of a silicon substrate (NG product) in which a crack has occurred, since the high frequency region component is relatively large, by limiting the vibration to a relatively high frequency region (for example, 8 KHz or more), The excitation force can be increased. Thereby, the difference between the silicon substrate (OK product) in which no crack is generated and the silicon substrate (NG product) in which the crack is generated is enlarged and can be easily determined.
[0066]
In each of the above-described embodiments, the electrode forming process in the case of manufacturing a solar battery cell has been described as an example of the process performed on the silicon substrate. According to this substrate screening apparatus, the processing is not limited to the case where cells are manufactured in a solar battery, but a substrate that may be damaged such as cracks when the substrate is processed is put into the production line. It can be eliminated in advance, and efficient production can be achieved while eliminating waste in the production line.
[0067]
The embodiment disclosed this time is to be considered as illustrative in all points and not restrictive. The present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0068]
【The invention's effect】
  According to the substrate screening apparatus in one aspect of the present invention,First,By stress applying means,By pressing the substrate against the concave part, the substrate deforms along the concave part,Stress that is substantially the same as the stress generated by a given process on the substrate in the production lineButPre-attached to the boardWill be.AndA substrate to which such stress is appliedBy vibration means and detection means,A substrate with or without damage such as cracksInCan be distinguished. As a result, it is possible to eliminate a substrate that may be damaged such as a crack during a predetermined process in the production line before putting such a substrate in the production line, thereby eliminating waste in the process of the production line. be able to.
[0069]
  SpecificallyThe concave portion of the strain generating mold part is a predetermined treatment in the difference in thermal expansion coefficient between the electrode material and the silicon substrate when a heat treatment for forming the electrode is performed in the manufacture of the solar cell using the silicon substrate. With a concave profile corresponding to the shape of the silicon substrate warped with the resulting stressPrefer to beYes.
[0070]
The substrate pressing portion preferably presses the substrate against the concave portion of the strain generating mold portion using the pressure of the gas, whereby the entire substrate can be pressed almost uniformly against the concave portion.
[0071]
In order to use such a gas pressure, the substrate pressing portion is opposed to the concave portion of the strain generating mold portion, and includes a pressing jig provided with a gas inlet, a pressing jig, and the strain generating mold portion. And a flexible sheet member for forming a closed space into which gas is sent to and from the holding jig. The pressure of the fed gas acts on the substrate via the sheet member.
[0072]
The vibration means preferably includes a means for hitting the substrate with an impulse hammer, whereby the substrate can be hit with a substantially constant excitation force.
[0073]
The detection means includes means for obtaining a sound pressure waveform from the captured sound signal and detecting the presence or absence of damage to the substrate based on the attenuation pattern of the sound pressure waveform in a specific frequency region caused by the crack. It is preferable that it can be determined that a crack has occurred in the substrate when vibration for a certain time is observed in the sound pressure waveform in the specific frequency range, and such a substrate can be easily removed. Can do.
[0074]
Alternatively, the vibration means preferably includes means for vibrating the substrate while changing the frequency by the signal generator. In this case, continuous vibration can be performed while changing the frequency in one vibration. The substrate can be identified more quickly.
[0075]
The detection means preferably includes means for obtaining a power spectrum from the captured sound signal and detecting the presence or absence of damage to the substrate based on the level of the power spectrum in the specific frequency domain caused by the crack. Thus, when the sound level is high in a frequency range above a specific frequency, it can be determined that a crack has occurred in the substrate, and such a substrate can be easily eliminated.
[0076]
  According to the substrate screening method in another aspect of the present invention,First,By the stress application process,By pressing the substrate against the concave part, the substrate deforms along the concave part,Stress that is substantially the same as the stress generated by a given process on the substrate in the production lineButPre-attached to the boardWill be.AndA substrate to which such stress is appliedBy the excitation process and detection process,A substrate with or without damage such as cracksInCan be distinguished. As a result, it is possible to eliminate a substrate that may be damaged such as a crack during a predetermined process in the production line before putting such a substrate in the production line, thereby eliminating waste in the process of the production line. be able to.
[0077]
In the stress applying step, it is preferable to apply stress to the substrate by gas pressure, whereby the entire substrate can be pressed almost uniformly against the concave portion, and predetermined stress is easily applied to the substrate. be able to.
[0078]
In the excitation process, the substrate is hit with an impulse hammer, and in the detection process, a sound pressure waveform is obtained from the captured sound signal, and the substrate is based on the attenuation pattern of the sound pressure waveform in a specific frequency domain caused by the crack. It is preferable to detect the presence or absence of damage to the substrate, so that it is possible to determine that a crack has occurred in the substrate when vibration for a certain period of time is recognized in the sound pressure waveform in a specific frequency region. The substrate can be easily eliminated.
[0079]
Alternatively, in the vibration process, the substrate is vibrated while changing the frequency by a signal generator, and in the detection process, a power spectrum is obtained from the captured sound signal, and the power spectrum level in a specific frequency region caused by the crack is obtained. It is preferable to detect the presence or absence of damage to the substrate based on this, so that if the sound level is high in a frequency range above a specific frequency, it can be determined that the substrate is cracked, Such a substrate can be easily eliminated.
[Brief description of the drawings]
FIG. 1 is a block diagram of a substrate screening apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a perspective view showing a step for explaining the substrate screening method in the embodiment.
3 is a perspective view showing a process performed after the process shown in FIG. 2 in the embodiment. FIG.
4 is a perspective view showing a holding jig for explaining a step performed after the step shown in FIG. 3 in the embodiment. FIG.
5 is a cross-sectional view showing a step performed after the step shown in FIG. 3 in the embodiment. FIG.
6 is a cross-sectional view showing a process performed after the process shown in FIG. 5 in the same Example; FIG.
7 is a side view showing a step performed after the step shown in FIG. 6 in the same embodiment. FIG.
8 shows a sound pressure waveform obtained in the step shown in FIG. 7 in the same embodiment, and (a), (c) and (e) show the sound pressure waveforms when a crack is not generated in the silicon substrate. (B), (d), and (f) are diagrams showing sound pressure waveforms after the filter processing is performed on the sound pressure waveforms of (a), (c), and (e), respectively.
9 shows the sound pressure waveform obtained in the step shown in FIG. 7 in the same embodiment. (A), (c) and (e) show the sound pressure waveform when a crack is generated in the silicon substrate. (B), (d), and (f) are diagrams showing sound pressure waveforms after the filter processing is performed on the sound pressure waveforms of (a), (c), and (e), respectively.
FIG. 10 is a side view showing one step for explaining a screening method according to Embodiment 2 of the present invention.
11 shows a power spectrum obtained in the step shown in FIG. 10 in the embodiment, and (a), (b) and (c) show the power spectrum when no cracks are generated in the silicon substrate. It is.
12 shows a power spectrum obtained in the step shown in FIG. 10 in the embodiment, and (a), (b) and (c) show the power spectrum when a crack is generated in the silicon substrate. It is.
FIG. 13 is a cross-sectional view showing a step for explaining the method for manufacturing a solar cell.
14 is a cross-sectional view showing a step performed after the step shown in FIG.
15 is a cross-sectional view showing a step performed after the step shown in FIG. 14;
FIG. 16 is a perspective view showing a silicon substrate after electrodes are formed.
FIG. 17 is another perspective view showing the silicon substrate after electrodes are formed.
FIG. 18 is a perspective view for explaining a problem of the silicon substrate after electrodes are formed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Silicon substrate, 1a surface, 1b back surface, 2 strain profile generation type, 2a concave profile part, 3 polyethylene sheet, 4 holding jig, 4a recessed part, 5 ports, 6 piping, 7 dry air, 8 impulse hammer, 9 board support Jig, 10 microphone, 11 shaking table, 12 arrows, 13 stress applying means, 14 micro crack detecting means, 15 good / defective product sorting means, 25, 27 Ag, 26 Al.

Claims (12)

A substrate screening apparatus for preliminarily removing a substrate that may be damaged by a stress caused by a predetermined process performed on the substrate in the production line before putting it into the production line,
Stress applying means for giving the substrate substantially the same stress as that applied to the substrate during a predetermined process;
Vibration means for applying vibration to the substrate to which stress is applied by the stress applying means;
Detecting the sound generated when the substrate vibrates by the vibration means, and detecting the presence or absence of damage to the substrate based on the signal of the captured sound ,
The stress applying means is
A strain generating mold portion having a concave portion corresponding to the shape of the warp of the substrate caused by the stress received by the substrate during a predetermined treatment;
A substrate pressing portion for pressing the substrate against the concave portion;
A substrate screening apparatus. The concave portion of the strain generating mold portion is a thermal expansion coefficient between the electrode material and the silicon substrate when the heat treatment for forming the electrode is performed in the manufacture of the solar cell using the silicon substrate as the predetermined treatment. The substrate screening apparatus according to claim 1, wherein the substrate screening apparatus has a concave profile corresponding to the shape of the silicon substrate warped in accordance with the stress caused by the difference .   The substrate screening apparatus according to claim 2, wherein the substrate pressing unit presses a substrate against the concave portion of the strain generating mold unit using gas pressure. The substrate pressing portion is
A pressing jig provided with a gas inlet, facing the concave portion of the strain generating mold portion;
And a flexible sheet member that is mounted between the pressing jig and the strain generating mold portion and forms a closed space into which gas is fed between the pressing jig. 3. The substrate screening apparatus according to 3.   The said screening means is a substrate screening apparatus in any one of Claims 1-4 containing a means which taps a board | substrate with an impulse hammer.   The detection means includes means for obtaining a sound pressure waveform from a captured sound signal and detecting presence / absence of damage to the substrate based on an attenuation pattern of a sound pressure waveform in a specific frequency region caused by a crack. 5. The substrate screening apparatus according to 5.   The said screening means is a board | substrate screening apparatus in any one of Claims 1-4 containing the means to vibrate a board | substrate, changing a frequency with a signal generator.   8. The detection unit according to claim 7, further comprising a unit that obtains a power spectrum from the captured sound signal and detects whether or not the substrate is damaged based on a level of a power spectrum in a specific frequency region caused by a crack. Substrate screening device. A substrate screening method for preliminarily removing a substrate that may be damaged by a stress caused by a predetermined process performed on the substrate in the production line before putting it into the production line,
A stress applying step for applying to the substrate substantially the same stress as that applied to the substrate during a predetermined process;
An excitation process for applying vibration to the substrate to which stress is applied in the stress application process;
Detecting the sound generated when the substrate vibrates in the vibration step, and detecting the presence or absence of damage to the substrate based on the captured sound signal ,
The substrate screening method, wherein, in the stress applying step, the substrate is pressed against a concave portion corresponding to the shape of the warp of the substrate caused by the stress applied to the substrate during a predetermined process.   The substrate screening method according to claim 9, wherein stress is applied to the substrate by gas pressure in the stress applying step. In the vibration step, the substrate is hit with an impulse hammer,
The detection step obtains a sound pressure waveform from a captured sound signal, and determines whether or not the substrate is damaged based on an attenuation pattern of a sound pressure waveform in a specific frequency region caused by a crack. A method for screening a substrate as described in 1. above. In the vibration step, the substrate is vibrated while changing the frequency by a signal generator,
11. The detection step according to claim 9, wherein in the detection step, a power spectrum is obtained from a captured sound signal, and the presence or absence of damage to the substrate is detected based on a level of a power spectrum in a specific frequency region caused by a crack. Substrate screening method.

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