JP6019417B2 - Semiconductor substrate cleaving method, solar cell cleaving method, and solar cell - Google Patents

Description

  The present invention relates to a semiconductor substrate cleaving method, a solar cell cleaving method, and a solar cell, which are cleaved by bending the semiconductor substrate.

  Conventionally, a single crystal silicon substrate obtained by thinly cutting ingot-shaped single crystal silicon has been used as a semiconductor substrate used for solar cells. Ingot-like single crystal silicon is produced by the Czochralski method (CZ method) or the floating zone melting method (FZ method), and has the same crystal orientation as the seed crystal.

  When a single crystal silicon substrate is used as a semiconductor substrate of a solar cell, the disk-shaped single crystal silicon substrate is divided into polygons to increase the light receiving area of the solar cell module (for example, patents) Reference 1). Specifically, a method of cleaving the single crystal silicon substrate by forming a plurality of divided grooves in the single crystal silicon substrate with a laser or a dicing saw and then bending the divided grooves along the divided grooves is employed.

JP-A-9-148601

  Here, since silicon has a diamond crystal structure, for example, a single crystal silicon substrate having a (100) plane has two cleavage planes, a (011) plane and a (0-1-1) plane. The single crystal silicon substrate has a property of being easily broken along a plane parallel to the cleavage plane. Therefore, when cleaving by bending along the dividing groove, the force necessary to cleave the dividing groove formed in parallel with the cleavage plane is to break the dividing groove not formed in parallel with the cleavage surface. Less than required force. That is, when some of the dividing grooves are formed in parallel with the cleavage plane, it is impossible to apply a uniform force to all of the dividing grooves.

  When such a non-uniform force is applied to the single crystal silicon substrate, there is a problem that stress concentrates on a part of the single crystal silicon substrate and the single crystal silicon substrate is cracked. Such a problem is not limited to a single crystal silicon substrate, but also applies to a III-V group compound semiconductor substrate having a zinc blende type structure such as GaAs.

  Then, this invention is made | formed in view of the subject mentioned above, and when cleaving a semiconductor substrate, the cleaving method of a semiconductor substrate which applies a uniform force to all the dividing grooves, the cleaving method of a solar cell, and a solar cell The purpose is to provide.

  According to a first aspect of the present invention, there is provided a method for cleaving a semiconductor substrate, comprising: forming a division groove having a predetermined depth on a semiconductor substrate; and bending the semiconductor substrate along the division groove. A step of cleaving the semiconductor substrate along the dividing groove, and the dividing groove is not parallel to the cleavage plane of the semiconductor substrate.

According to the method for cleaving a semiconductor substrate according to the first aspect of the present invention, by forming a dividing groove so as not to be parallel to the cleavage plane of the semiconductor substrate, and bending the semiconductor substrate along the dividing groove,
The semiconductor substrate is cleaved along the dividing groove. Therefore, since the dividing grooves are not parallel to the cleavage plane of the semiconductor substrate, a uniform force can be applied to all the dividing grooves when the semiconductor substrate is cleaved. That is, when the semiconductor substrate is cleaved, stress is not concentrated on a part of the semiconductor substrate. As a result, since the semiconductor substrate is cleaved without causing cracks, the yield in the semiconductor substrate dividing step can be improved.

  A method for cleaving a solar cell according to a second feature of the present invention includes a step of forming a photoelectric conversion part having a semiconductor pn junction or a semiconductor pin junction using a semiconductor substrate, and a predetermined pattern on the photoelectric conversion part. Forming a conductive electrode; forming a dividing groove having a predetermined depth on the photoelectric conversion unit according to the predetermined pattern; and bending the photoelectric conversion unit along the dividing groove. And the step of cleaving the photoelectric conversion unit along the dividing groove, and the dividing groove is not parallel to the cleavage plane of the semiconductor substrate.

  A solar cell according to a third aspect of the present invention includes a photoelectric conversion unit having a semiconductor pn junction or a semiconductor pin junction using a semiconductor substrate, and a collector electrode formed in a predetermined pattern on the photoelectric conversion unit. And the side surface of the photoelectric conversion part includes a cleaved surface that is cleaved by bending, and the gist is that the cleaved surface is not parallel to the cleavage plane of the semiconductor substrate.

  ADVANTAGE OF THE INVENTION According to this invention, when cleaving a semiconductor substrate, the cleaving method of the semiconductor substrate which applies uniform force to all the division | segmentation grooves, the cleaving method of a solar cell, and a solar cell can be provided.

Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.
<Configuration of solar cell module>

  A configuration of the solar cell module 100 according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view of a solar cell module 100 according to the present embodiment. FIG. 2 is an enlarged cross-sectional view of the solar cell 101 according to the present embodiment. In FIG. 2, the lower surface is shown as the light receiving surface of the solar cell 101.

  The solar cell module 100 includes a solar cell 101, a wiring material 102, a sealing material 103, a light receiving surface side protective material 104, and a back surface side protective material 105.

  As shown in FIG. 2, the solar cell 101 includes a photoelectric conversion unit 10, a light receiving surface side collector electrode 6, and a back surface side collector electrode 7.

  The photoelectric conversion unit 10 generates carriers by receiving light. The carrier refers to a pair of holes and electrons generated when light is absorbed by the photoelectric conversion unit 10. The photoelectric conversion unit 10 according to the present embodiment has a semiconductor pin junction as a basic structure. Specifically, the photoelectric conversion unit 10 includes an n-type single crystal silicon substrate 1, an i-type amorphous silicon layer 2i, a p-type amorphous silicon layer 2p, a transparent conductive film 3, and an i-type amorphous silicon layer 4i. The n-type amorphous silicon layer 4n and the transparent conductive film 5 are provided. On the light-receiving surface (lower surface) side of the n-type single crystal silicon substrate 1, an i-type amorphous silicon layer 2i, a p-type amorphous silicon layer 2p, and a transparent conductive film 3 are sequentially stacked. On the back surface (upper surface) side of the n-type single crystal silicon substrate 1, an i-type amorphous silicon layer 4i, an n-type amorphous silicon layer 4n, and a transparent conductive film 5 are sequentially stacked.

  Here, the side surface of the photoelectric conversion unit 10 according to the present embodiment includes a fractured surface that is cleaved by bending, and the fractured surface is not parallel to the cleavage plane of the n-type single crystal silicon substrate 1. Since such a fractured surface relates to a characteristic part of the present invention, a cleavage method for forming the fractured surface will be described in detail later.

  The light receiving surface side collecting electrode 6 is formed in a comb shape on the light receiving surface of the transparent conductive film 3. The back surface side collecting electrode 7 is formed in a comb shape on the back surface of the transparent conductive film 5. The light-receiving surface side collecting electrode 6 and the back surface side collecting electrode 7 collect light-generated carriers that the photoelectric conversion unit 10 generates by receiving light.

  The solar cell module 100 including the solar cell 101 configured as described above is called a HIT type solar cell module. The solar cells 101 are electrically connected to each other by the wiring material 102.

  The sealing material 103 seals a plurality of solar cells 101 that are electrically connected to each other by the wiring material 102. The sealing material 103 can be formed using a resin material such as EVA (ethylene / vinyl / acetylate) or PVB (poly / vinyl / butyral).

  The light-receiving surface side protective material 104 is configured using a member that transmits most of light having a wavelength that can be absorbed by the solar cell 101. As the light receiving surface side protective material 104, glass, plastic, or the like can be used.

The back surface side protective material 105 is a resin film such as PET (polyethylene terephthalate), a resin film on which a metal oxide vapor deposition film such as alumina is formed, a metal film such as aluminum foil, or a film in which these are laminated. .
<Method for Manufacturing Solar Cell Module 100>

  A method for manufacturing the solar cell module 100 according to the present embodiment will be described. First, an n-type single crystal silicon substrate 1 having a disk-shaped (100) plane obtained by thinly cutting an ingot-shaped n-type single crystal silicon is prepared. Here, as shown in FIG. 3, the n-type single crystal silicon substrate 1 includes a first cleavage plane ((011) plane) indicated by a reference line α and a second cleavage plane indicated by a reference line β. Surface ((0-1-1) surface). Further, the reference line α and the reference line β are orthogonal to each other.

  Next, the n-type single crystal silicon substrate 1 is anisotropically etched with an alkaline aqueous solution to form fine irregularities on the surface. Further, the surface of the n-type single crystal silicon substrate 1 is washed to remove impurities.

  Next, an i-type amorphous silicon layer 2i and a p-type amorphous silicon layer 2p are sequentially stacked on the light-receiving surface of the n-type single crystal silicon substrate 1 using a vapor phase growth method such as an RF plasma CVD method. To do. Similarly, an i-type amorphous silicon layer 4 i and an n-type amorphous silicon layer 4 n are sequentially stacked on the back surface of the n-type single crystal silicon substrate 1.

  Next, an ITO film (transparent conductive film 3) is formed on the light receiving surface of the p-type amorphous silicon layer 2p by using a magnetron sputtering method. Similarly, an ITO film (transparent conductive film 5) is formed on the back surface of the n-type amorphous silicon layer 4n. Thus, the disk-shaped photoelectric conversion unit 10 having a pin junction using the disk-shaped n-type single crystal silicon substrate 1 is formed.

Next, an epoxy thermosetting silver paste is formed in a comb shape on the light receiving surface of the ITO film (transparent conductive film 3) using a printing method such as a screen printing method or an offset printing method. As a result, the light receiving surface side collecting electrode 6 is formed on the light receiving surface of the photoelectric conversion unit 10. Similarly, an epoxy thermosetting silver paste is formed in a comb shape on the back surface of the ITO film (transparent conductive film 3). Thereby, the back surface side collector electrode 7 is formed on the back surface of the photoelectric conversion unit 10. As shown in FIG. 3, the back surface side collecting electrode 7 is formed so as not to be parallel to the reference line α and the reference line β. FIG. 3 shows the back surface side collecting electrode 7 formed on the back surface of the photoelectric conversion unit 10. The light receiving surface side collecting electrode 6 is formed on the light receiving surface of the photoelectric conversion unit 10 substantially symmetrically with the back surface side collecting electrode 7 (not shown).

  Next, the silver paste is heated under predetermined conditions to volatilize the solvent, and then further heated to perform main drying. Thus, the disk-shaped solar cell 101 is manufactured.

  Next, according to the comb-shaped pattern in which the back surface side collecting electrode 7 is formed, a dividing groove is formed on the back surface side of the photoelectric conversion unit 10, and the photoelectric conversion unit 10 is cut along the dividing groove. In the present embodiment, the photoelectric conversion unit 10 is divided into four parts by cleaving according to the comb-shaped pattern in which the back-side collecting electrode 7 is formed. The cleaving method is described later in detail because it relates to a characteristic part of the present invention.

  Next, a light receiving surface side collector electrode 6 formed on the light receiving surface of one solar cell 101 and a back surface side collector electrode 7 formed on the back surface of another adjacent solar cell 101 are tabbed ( The wiring member 102) is electrically connected.

  Next, an EVA sheet (sealing material 103), a plurality of solar cells 101 connected by tabs, an EVA sheet (sealing material 103), and a PET film (back side) on a glass substrate (light-receiving surface side protective material 104) The protective material 105) is sequentially laminated to form a laminated body.

  Next, the laminated body is temporarily pressure-bonded by thermocompression bonding in a vacuum atmosphere, and then the EVA is completely cured by heating under a predetermined condition.

Thus, the solar cell module 100 is manufactured. Note that a terminal box, an Al frame, or the like can be attached to the solar cell module 100.
<Cleaving method of solar cell 101>

  Next, the cutting method of the solar cell 101 will be described in detail with reference to the drawings. FIG. 4 shows the dividing grooves 8 formed on the back surface of the solar cell 101. FIG. 5 is an enlarged view of a portion AA in FIG. 6 is an enlarged view of the BB cross section of FIG.

  First, the dividing grooves 8 are formed by irradiating laser light from the back side of the solar cell 101 using a YAG laser or the like. As the irradiation conditions of the YAG laser, the wavelength of the second harmonic is 400 nm or more, the frequency is 1 kHz to 50 kHz, the light diameter is 20 to 200 μm, and the output is 1 to 25 W. By using such irradiation conditions, the dividing grooves 8 having a width substantially equal to the light diameter of the laser light are formed.

  Here, as shown in FIG. 4, the dividing groove 8 according to the present embodiment is formed so as not to be parallel to the reference line α and the reference line β. That is, the dividing groove 8 is not parallel to the first cleavage plane ((011) plane) and the second cleavage plane ((0-1-1) plane) of the n-type single crystal silicon substrate 1.

Specifically, as shown in FIG. 5, the dividing groove 8 a has an inclination of an angle γ (15 degrees) with respect to a reference line α ′ that is a parallel line of the reference line α, and an angle with respect to the reference line β. It has a slope of δ (75 degrees). The dividing groove 8b has an inclination of an angle φ (15 degrees) with respect to the reference line α ′ and an inclination of an angle ε (75 degrees) with respect to the reference line β. Thus, all the dividing grooves 8 have an inclination with respect to the reference line α and the reference line β. In addition, the magnitude | size of the inclination of the division | segmentation groove | channel 8 with respect to the reference line (alpha) and the reference line (beta) can be set arbitrarily. Moreover, the division | segmentation groove | channel 8 should just have inclination of arbitrary magnitude | size with respect to the reference line (alpha) and the reference line (beta), and according to the pattern of the back surface side collector electrode 7 formed on the photoelectric conversion part 10. FIG. And can be formed at any position.

  As shown in FIG. 6, the dividing groove 8 according to this embodiment has a depth d (60 μm to 80 μm) from the back surface side with respect to the thickness T (140 μm to 190 μm) of the photoelectric conversion unit 10. The depth d of the dividing groove 8 is not limited to this and can be arbitrarily set, but it is preferable that the depth d does not reach the p-type amorphous silicon layer 2p.

  Next, the photoelectric conversion unit 10 is cut along the dividing groove 8 by bending the photoelectric conversion unit 10 along the dividing groove 8.

  Specifically, as shown in FIG. 7, first, the solar cell 101 is fixed between the mounting table 20 and the press member 30, and the cleaving blade 40 is moved downward, whereby the divided groove 8 (divided groove). The photoelectric conversion unit 10 is cleaved along (except 8d and 8e). That is, the photoelectric conversion unit 10 is cleaved by bending the outer peripheral portion of the photoelectric conversion unit 10 downward. As shown in FIGS. 8A to 8C, the mounting table 20, the pressing member 30, and the cutting blade 40 have the same shape and substantially the same shape as the dividing grooves 8 (except for the dividing grooves 8d and 8e) in plan view. Dimensions. As described above, the outer peripheral portion of the solar cell 101 is cleaved and formed into a polygonal shape as shown in FIG.

  Subsequently, the photoelectric conversion unit 10 is cut along the divided grooves 8d and 8e by bending the photoelectric conversion unit 10 along the divided grooves 8d and 8e. The cleaving of the photoelectric conversion unit 10 along the dividing grooves 8d and 8e is performed by bending the photoelectric conversion unit 10, and the bending order is not limited. For example, after the photoelectric conversion unit 10 is divided into two by cleaving along the dividing groove 8d, each is cleaved along the dividing groove 8e. As a result, the solar cell 101 is divided into four as shown in FIG.

  Solar cell module 100 is manufactured by electrically connecting solar cells 101 formed in this way with tabs.

<Action and effect>
According to the solar cell cleaving method according to the present embodiment, the n-type single crystal silicon substrate 1 is parallel to the first cleavage plane ((011) plane) and the second cleavage plane ((0-1-1) plane). The dividing groove 8 is formed so as not to become. Further, the photoelectric conversion unit 10 is cut along the dividing groove 8 by bending the photoelectric conversion unit 10 along the dividing groove 8.

  Thus, since the dividing groove 8 is not parallel to the cleavage plane of the n-type single crystal silicon substrate 1, a uniform force can be applied to all the dividing grooves 8 when the photoelectric conversion unit 10 is cleaved. That is, when the photoelectric conversion unit 10 is cleaved, stress does not concentrate on a part of the n-type single crystal silicon substrate 1.

Therefore, the photoelectric conversion unit 10 can be cleaved without causing cracks in the n-type single crystal silicon substrate 1, so that the yield in the dividing step of the solar cell 101 can be improved. <Other embodiments>
Although the present invention has been described according to the above-described embodiments, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

For example, in the above embodiment, the n-type single crystal silicon substrate 1 is used, but a p-type single crystal silicon substrate can be used. In this case, i is formed on the light receiving surface side of the p-type single crystal silicon substrate.
An n-type amorphous silicon layer and an n-type amorphous silicon layer are sequentially stacked, and an i-type amorphous silicon layer and a p-type amorphous silicon layer are sequentially formed on the back side of the p-type single crystal silicon substrate. What is necessary is just to laminate.

  In the above embodiment, the n-type single crystal silicon substrate 1 is used, but a compound semiconductor substrate can be used. For example, when a GaAs substrate is used, the dividing groove 8 may be formed so as not to be parallel to the first cleavage plane ((110) plane) and the second cleavage plane ((1-10) plane) of the GaAs substrate. .

  In the above embodiment, the case where the photoelectric conversion unit 10 has a semiconductor pin junction using the n-type single crystal silicon substrate 1 has been described. However, the photoelectric conversion unit 10 has a semiconductor pn junction using a semiconductor substrate. You may have. In this case, a pn junction can be formed by doping a p-type or n-type dopant on the surface of an n-type or p-type crystalline semiconductor substrate.

In the above embodiment, the method for cleaving the solar cell 101 using the n-type single crystal silicon substrate 1 has been described, but the present invention can also be applied to semiconductor substrates other than solar cells.
Further, in the above embodiment, the light receiving surface side collecting electrode 6 and the back surface side collecting electrode 7 are formed in a comb shape, but these formation patterns can be arbitrarily designed.

  Moreover, in said embodiment, although the disk-shaped solar cell 101 was divided into four by cleaving, the shape of the solar cell 101 after the cleaving is not limited. Therefore, the formation pattern of the dividing grooves 8 is not limited to that described in the above embodiment.

  Further, in the above embodiment, the outer peripheral portion of the disk-shaped solar cell 101 is collectively cut using the cleaving device. However, it is not always necessary to cleave all at once, for example, divided grooves formed in parallel. One set can be cleaved from each other.

It is sectional drawing of a solar cell module provided with the solar cell which concerns on embodiment. It is sectional drawing of the solar cell which concerns on embodiment. It is a top view of the solar cell which concerns on embodiment. It is a figure for demonstrating the cleaving method of the solar cell which concerns on embodiment (the 1). It is an AA partial enlarged view of FIG. It is BB expanded sectional drawing of FIG. It is a side view which shows the cleaving apparatus used for the cleaving of the solar cell which concerns on embodiment. It is a figure which shows the components of the cleaving apparatus shown in FIG. It is a figure for demonstrating the cleaving method of the solar cell which concerns on embodiment (the 2). It is a figure for demonstrating the cleaving method of the solar cell which concerns on embodiment (the 3).

  1 ... n-type single crystal silicon substrate, 2i ... i-type amorphous silicon layer, 2p ... p-type amorphous silicon layer, 3 ... transparent conductive film, 4i ... i-type amorphous silicon layer, 4n ... n-type non-crystalline Crystalline silicon layer, 5 ... transparent conductive film, 6 ... light-receiving surface side collecting electrode, 7 ... back surface side collecting electrode, 8 ... divided groove, 8a ... divided groove, 8b ... divided groove, 8c ... divided groove, 8d ... Dividing groove, 8e ... dividing groove, 10 ... photoelectric conversion unit, 20 ... mounting table, 30 ... pressing member, 40 ... cleaving blade, 100 ... solar cell module, 101 ... solar cell, 102 ... wiring material, 103 ... sealing material , 104: light-receiving surface side protective material, 105 ... back surface side protective material, α ... reference line, β ... reference line, γ ... angle, δ ... angle, ε ... angle, φ ... angle

Claims (3)

Forming a photoelectric conversion portion having a semiconductor pn junction or a semiconductor pin junction on a crystalline semiconductor substrate;
A second step of forming a dividing groove having a predetermined depth in the crystalline semiconductor substrate after the first step;
After the second step, a third step of cleaving the crystalline semiconductor substrate along the dividing groove by bending the crystalline semiconductor substrate along the dividing groove;
With
The third step includes a step of cleaving the crystalline semiconductor substrate using a cleaving device including a mounting table for placing the crystalline semiconductor substrate, a press member, and a cleaving blade,
The step is a step of fixing the crystal semiconductor substrate between the mounting table and the press member, moving the cleaving blade, bending the outer peripheral portion of the crystal semiconductor substrate along the dividing groove, and cleaving the crystal semiconductor substrate. Yes,
The outer peripheral shape of the dividing groove is a polygonal shape in plan view, and all the dividing grooves are not parallel to the cleavage plane of the crystalline semiconductor substrate,
The mounting table, the pressing member, and the cutting blade of the cleaving device have substantially the same shape and the same size as the dividing groove in plan view.
A method for manufacturing a solar cell. It is a manufacturing method of the solar cell of Claim 1, Comprising:
The mounting table, the press member, and the cutting blade of the cleaving device have substantially the same shape and dimensions as a part of the dividing groove in plan view.
A method for manufacturing a solar cell. It is a manufacturing method of the solar cell of Claim 1 or 2 , Comprising:
The division groove having the predetermined depth is formed by irradiating the crystal semiconductor substrate with laser light.

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