JP5664738B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a method for manufacturing a semiconductor device such as a solar battery cell.

  At present, cost reduction is an important issue for methods used in manufacturing semiconductor devices such as consumer solar cells and power devices such as diodes and transistors. Therefore, when slicing a substrate from a crystal ingot, a slicing method using a multi-wire saw is generally employed, and semiconductor devices such as solar cells are manufactured using the substrate thus obtained. The details are as follows, for example in the case of a photovoltaic cell.

First, a p-type silicon substrate obtained by slicing a single crystal silicon ingot pulled up by the Czochralski (CZ) method or a polycrystalline silicon ingot produced by a cast method by a multi-wire method is prepared. Next, after removing slicing damage on the surface with an alkaline solution, fine unevenness (texture) having a height of about 1 to 20 μm is formed on the surface (light receiving surface), and n-type is formed on the substrate surface (light receiving surface) by a thermal diffusion method. Forming a diffusion layer. Next, the vicinity of the substrate end surface is etched by a method such as a dry or wet etching method or a laser ablation method to perform junction separation. Subsequently, a TiO ₂ or SiN film is deposited on the light receiving surface with a film thickness of, for example, about 70 to 100 nm to form an antireflection film. Next, a back electrode is formed by printing and baking a material mainly composed of aluminum over the entire back surface using a screen printing method. On the other hand, the light-receiving surface electrode is formed by printing and baking a material containing silver as a main component, for example, in a comb-teeth shape having a width of about 100 to 200 μm.
In addition, the following are mentioned as prior art documents relevant to the present invention.

JP-A-5-211128

  Conventionally, when a substrate is obtained by a slicing method such as a multi-wire saw, there is a problem that at least the wire thickness of the multi-wire saw is lost as kerf loss (cutting allowance loss). In addition, as the required substrate thickness is reduced, the ratio of kerf loss to the semiconductor material ingot increases, and the mechanical strength of the obtained substrate decreases, resulting in a decrease in yield in the manufacturing process.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a semiconductor device with high productivity without reducing kerf loss due to slicing of a semiconductor substrate and reducing the mechanical strength of the substrate. And

  As a result of intensive studies to achieve the above object, the present inventors have implanted hydrogen ions or rare gas ions to a predetermined depth of a semiconductor substrate to form an ion implanted layer, and heat-treated the substrate to produce the ion implanted layer. To obtain a separation substrate having a cross section (separation surface) substantially parallel to the substrate surface (main surface), and then heat-treating the separation substrate in the presence of a dopant of a different conductivity type. By forming a dopant diffusion layer in which the dopant is diffused on the surface (surface that becomes the light receiving surface), and then forming an electrode that is electrically connected to the dopant diffusion layer on the surface of the separation substrate (light receiving surface), It has been found that kerf loss due to slicing of a semiconductor substrate can be reduced, and a semiconductor device can be manufactured with high productivity without reducing the mechanical strength of the substrate. In particular, since the separation heat treatment for obtaining the separation substrate and the diffusion heat treatment for forming the dopant diffusion layer are simultaneously performed in a single heat treatment, the number of processed substrates can be reduced, so that the semiconductor is more economical and more productive. The present inventors have found that a device can be manufactured and have made the present invention.

That is, the present invention provides the following semiconductor device manufacturing method.
Claim 1:
A step of forming an ion implantation layer by implanting hydrogen ions or rare gas ions from a surface of the original substrate, which is a semiconductor substrate having a thickness of 100 to 400 μm, which has been planarized, to a predetermined depth from the surface of the original substrate. ,
Thereafter, the original substrate is heat-treated in the presence of a dopant having a conductivity type different from that of the original substrate to separate the original substrate in the ion-implanted layer and to have two separated substrates having a cross section substantially parallel to the original substrate surface. with obtaining, the step of the two separate substrates each of the original substrate surface or rear surface is a surface of the dopant forming dopant diffusion layer is diffused, and the dopant diffusion layer electrically to said separating substrate surface The manufacturing method of the semiconductor device characterized by including the process of forming the electrode to connect electrically.
Claim 2:
Further, after the step of forming the ion-implanted layer, before the step of obtaining the two separated substrates by the heat treatment, a texture composed of fine irregularities having a height of 1 to 20 μm is formed on the front and back surfaces of the original substrate. The method for manufacturing a semiconductor device according to claim 1, further comprising a step.
Claim 3:
3. The method of manufacturing a semiconductor device according to claim 2, wherein the thickness of the original substrate is the sum of the thicknesses of the two separation substrates plus the substrate thickness lost due to the texture formation. .
Claim 4:
The method of manufacturing a semiconductor device according to claim 1, wherein the semiconductor device is a solar battery cell.
Claim 5:
The method for manufacturing a semiconductor device according to claim 4, wherein the diffusion heat treatment temperature is 800 to 1100 ° C.
Claim 6:
Further, after the formation of the dopant diffusion layer, the method includes a step of etching at least a cross section of the separation substrate. The etching removes the dopant diffusion layer formed on the cross section of the separation substrate and removes damage on the cross section. The method for manufacturing a semiconductor device according to claim 1.
Claim 7:
The semiconductor device manufacturing method according to claim 1, wherein the semiconductor device is a power device.
Claim 8:
The method of manufacturing a semiconductor device according to claim 7, wherein the diffusion heat treatment temperature is 800 to 1350 ° C.

  According to the semiconductor device manufacturing method of the present invention, by obtaining a semiconductor substrate by an ion implantation separation method, crystal kerf loss can be reduced as compared with the conventional slicing method, and the mechanical strength of the substrate is increased until the separation heat treatment is completed. Yield can be improved. In particular, since the dopant diffusion heat treatment and the substrate separation heat treatment are performed simultaneously in a single heat treatment, the number of substrates to be processed can be reduced, which is more economical and can improve productivity.

It is the schematic which shows an example of the manufacturing method of a photovoltaic cell as an example of the semiconductor device which concerns on this invention. (A) is a substrate, (b) is an ion-implanted state, (c) is a textured state, (d) is a state in which the substrate is separated and a diffusion layer is formed, and (e) is a joint-separated and separated state The surface damage is removed by etching, (f) shows a state where a surface protective film (antireflection film) is formed, and (g) shows a state where a light receiving surface and a back electrode are formed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

  In FIG. 1, the example of the manufacturing method of a photovoltaic cell is shown as an example of the manufacturing method of the semiconductor device of this invention. As shown in FIG. 1A, a semiconductor crystal or the like is used as the semiconductor substrate (original substrate) 1 used in the present invention. When the semiconductor crystal is silicon, the Czochralski (CZ) method or Either a single crystal produced by the float zone (FZ) method may be used, but the single crystal by the CZ method is more suitable from the viewpoint of cost. The conductivity type may be n-type or p-type.

  The crystal plane orientation of the single crystal is preferably (100) when anisotropic etching with an alkaline solution is used when forming a texture to be described later, but other crystals are used when physical grinding is performed using a grinder or the like. It does not matter in the plane orientation. The substrate specific resistance is preferably, for example, 0.1 to 20 Ω · cm, and in particular, 0.5 to 2 Ω · cm is suitable for producing a high-performance solar cell.

  When using a semiconductor single crystal, the semiconductor base substrate 1 is produced from a semiconductor crystal ingot such as silicon (FIG. 1A). The semiconductor base substrate may be manufactured by any method such as a slicing method using a multi-wire saw or the like, an ion implantation using a hydrogen ion or rare gas ion implantation apparatus, and an ion implantation separation method using a separation heat treatment. For the production of the semiconductor base substrate by the ion implantation separation method, for example, a method disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 5-211128: a method for producing a thin semiconductor film) may be used. Specifically, hydrogen ions or rare gas ions are implanted to a predetermined depth of a semiconductor ingot such as silicon to form an ion implantation layer, and this is heat-treated, so that the implanted hydrogen ions and the like aggregate to form microbubbles. The semiconductor ingot is divided in the ion implantation layer by the pressure action of the microbubbles and the rearrangement action of the semiconductor crystal, and an original substrate having a predetermined thickness can be obtained.

In this case, the ion species to be ion-implanted may be hydrogen ions or rare gas ions such as helium, neon, krypton, and xenon, which may be used alone or in combination of two or more. When the type of semiconductor to be ion-implanted is silicon and the ion species to be implanted is hydrogen ions, the implantation temperature is 20 to 450 ° C., and the ion implantation dose is 1 × 10 ¹⁶ to 1 × 10 ¹⁸ ions · cm ⁻² . It is preferable. Moreover, it is desirable to perform the heat treatment at 500 ° C. or higher. When the implanted ions are hydrogen ions, by heating at a temperature of 500 ° C. or higher, as described above, the implanted hydrogen ions are aggregated to generate microbubbles, and the semiconductor ingot is divided.

  In the present invention, as will be described later, the semiconductor original substrate obtained by the above method is further subjected to ion implantation and separation heat treatment to separate the semiconductor original substrate into at least two substrates. For this reason, it is desirable that the original substrate surface (main surface) serving as the ion implantation surface is not damaged by mechanical grinding such as slicing so that the ion implantation depth at this time is constant. Therefore, when the original substrate is manufactured using the slicing method, it is better to flatten the surface (main surface) by etching away the damaged portion (damage layer) after slicing with an acid or an alkali solution. On the other hand, when using the ion implantation separation method, if the first ion implantation surface to the ingot is flattened by etching or polishing, the flatness of the separation surface of the original substrate obtained after separation is high, and the damage of the separation surface is high. Therefore, no special planarization process is necessary for further ion implantation separation. Therefore, as a method for manufacturing the original substrate, the ion implantation separation method is preferable because it can further reduce the semiconductor crystal loss and simplify the process, but any method may be used.

  The thickness of the original substrate obtained at this time is equal to or greater than the total thickness of the semiconductor substrate of the finally obtained solar battery cell, for example, when separated into two, it is preferably equal to or greater than the total thickness of two. Usually, it is preferable that it is 100-400 micrometers. Specifically, for example, when two solar cells having a final semiconductor substrate thickness of 100 μm are manufactured, the substrate thickness is lost by about 10 to 20 μm due to texture formation to be described later. The thickness may be about 210 to 220 μm.

Next, hydrogen ions or the same rare gas ions as described above are implanted to a predetermined depth of the original substrate using a hydrogen ion or rare gas ion implantation apparatus to form the ion implantation layer 2 (FIG. 1B). In the ion implantation, when the type of semiconductor to be ion-implanted is silicon and the ion species to be implanted is hydrogen ion, the implantation temperature is preferably 20 to 450 ° C., and the implantation dose is 1 × 10 ¹⁶ to 1 × 10 ¹⁸ ions · cm. ^-2 is preferred. If the injection dose is too small, separation may not be performed by the separation heat treatment, and if it is too large, cost may be wasted. The depth of the ion implantation layer from the original substrate surface (main surface) is preferably about the same as the thickness of the finally required semiconductor substrate (separation substrate). For example, when the original substrate is 210 to 220 μm thick, By implanting ions from the surface (main surface) to a depth of 105 to 110 μm, two separation substrates having substantially the same thickness can be obtained, but the thickness of the finally obtained semiconductor substrate (separation substrate) is: It may be the same or not necessarily the same.

  After that, an uneven shape called texture is formed on the front and back surfaces of the original substrate (the surface that becomes the light receiving surface of the separation substrate) (FIG. 1C). The reason for forming the texture 3 is that when the solar battery cell is formed, in order to reduce the reflectance in the visible light region, it is necessary to perform reflection at least twice as much as possible on the light receiving surface. The texture can be formed, for example, by immersing the original substrate in an aqueous solution obtained by adding isopropyl alcohol to sodium hydroxide having a concentration of 1 to 5 mass% and performing wet etching to form a random texture on both surfaces. The size of each mountain is preferably about 1 to 20 μm. Other typical surface uneven structures include V-grooves and U-grooves. These can also be formed by using a grinder. In order to create a random concavo-convex structure, acid etching, reactive ion etching, or the like can be used as an alternative method. In addition, although the example which forms a texture after ion implantation was shown in FIG. 1, you may ion-implant after forming a texture.

  A diffusing agent containing a dopant is applied to the front and back surfaces of the original substrate that has been ion-implanted and textured. A dopant having a conductivity type different from that of the substrate is used. For example, when the substrate to be used is p-type, an n-type diffusion layer can be formed on the original substrate surface (main surface) if a diffusing agent containing phosphorus or the like is used. When the substrate to be used is n-type, a p-type diffusion layer can be formed by using a diffusing agent containing boron or the like. The method for applying the diffusing agent may be any method such as spin coating, spray coating, or dipping.

  Next, separation heat treatment is performed to separate the original substrate at the ion-implanted depth to obtain an isolated substrate having a cross section substantially parallel to the original substrate surface (main surface). In this case, when the ions implanted into the original substrate are hydrogen ions, by heating to 500 ° C. or higher, the hydrogen ions aggregate to generate microbubbles, and the original substrate is separated. As a method for carrying out the separation heat treatment, it can be carried out by grooving a boat, placing it in a heat treatment furnace (core tube), and processing with a predetermined thermal profile. At this time, materials such as quartz and silicon carbide (SiC) can be used for the boat and the core tube used. Quartz is preferable in terms of purity and cost.

Thereafter, diffusion heat treatment is performed using a heat treatment furnace (core tube) similar to the above to form a dopant diffusion layer on the substrate surface (light receiving surface). The thermal profile of the diffusion heat treatment varies depending on the type and concentration of dopant contained in the diffusing agent used, other components such as silica and silicate, the amount of diffusing agent applied to the substrate, and the like. For example, when using a diffusing agent containing phosphorus, it can be carried out by treating at 800 to 1100 ° C., preferably 800 to 1050 ° C., particularly 850 to 950 ° C. for about 10 to 120 minutes, particularly about 15 to 60 minutes. In the case of a diffusing agent containing boron, the treatment is preferably performed at 800 to 1100 ° C., preferably 850 to 1100 ° C., particularly 900 to 1000 ° C. for 10 to 120 minutes, particularly 15 to 60 minutes.
In addition, when manufacturing a power device, the diffusion heat treatment temperature of phosphorus is preferably 800 to 1350 ° C., more preferably 800 to 1100 ° C., further preferably 800 to 1050 ° C., particularly preferably 850 to 950 ° C. The diffusion heat treatment temperature is preferably 800 to 1350 ° C, more preferably 800 to 1100 ° C, still more preferably 850 to 1100 ° C, and particularly preferably 900 to 1000 ° C. Other conditions are the same as above.

  Various types of gases can be used as the process gas during the diffusion heat treatment, but when considering the purity and cost, for example, an inert gas such as argon or nitrogen and oxygen can be used. The flow rate of the process gas varies depending on the capacity of the heat treatment furnace to be used. For example, when a furnace tube having an inner diameter of 150 to 350 mm and a length of about 1500 to 3500 mm is used, argon and nitrogen are used in an amount of 5 to 40 L / min and oxygen is used. The flow rate may be about 0.025 to 0.2 L / min.

  The separation heat treatment and the diffusion heat treatment may be performed separately, but in the present invention, it is preferable to perform them simultaneously in one heat treatment profile. That is, in the present invention, a heat treatment is performed on the original substrate on which the ion implantation is performed and the diffusing agent is applied, so that the original substrate is separated into two separation substrates 1 ′ having the separation surface 4; Diffusion heat treatment for forming the dopant diffusion layer 5 on the front and back surfaces (light receiving surfaces of the separated substrates) can be performed simultaneously by one heat treatment (FIG. 1D). As the processing conditions such as the thermal profile of the separation heat treatment / diffusion heat treatment, the above-described diffusion heat treatment conditions can be employed.

  In addition, when forming a diffusion layer by the vapor phase diffusion method using phosphorus oxychloride, diborane, etc., it is not necessary to apply a diffusing agent in advance. In the case of performing the vapor phase diffusion method, a gas containing a dopant component such as phosphorus oxychloride or diborane may be flowed at the time of the diffusion heat treatment (separation heat treatment / diffusion heat treatment). The separation substrate obtained at this point basically has a texture and a dopant diffusion layer formed on the light receiving surface (front surface) side, and a non-light receiving surface (back surface) side as a separation surface.

  Subsequently, for example, the junction separation process can be performed here. Junction separation means that a positive electrode and a negative electrode of a solar battery cell are short-circuited by being connected by a high-concentration dopant diffusion layer of the same conductivity type, and the diffusion layer is partially removed in order to prevent deterioration of characteristics. Thus, the positive electrode and the negative electrode are structured not to be connected by the same conductivity type dopant diffusion layer. As a bonding separation method, any method such as a method of etching a substrate such as dry etching or wet etching, a physical grinding method using a grinding machine, or an ablation method using a laser beam may be used. The junction separation is not necessarily performed after the diffusion heat treatment, and may be performed after the formation of a surface protective film described later.

  In order to obtain a more efficient solar cell, the junction separation is performed by removing the dopant diffusion layer formed on the separation surface of the separation substrate after the separation heat treatment, for example, by wet etching the entire back surface, and at the separation surface. A method that can simultaneously remove the remaining damaged portion (damage layer) is desirable (FIG. 1E). FIG. 1E shows an example in which the etching junction separation of the substrate end face (side face) and the separation face damage layer are simultaneously removed by etching. In the figure, 6 is an etching surface.

  A dopant glass layer (phosphorus glass layer in the case of phosphorus, boron glass layer in the case of boron) is formed on the surface of the substrate subjected to the diffusion heat treatment, and serves as a surface recombination center. The dopant glass layer is removed. Depending on the diffusing agent used, hydrogen fluoride alone may not be removed, so that general cleaning of the semiconductor may be continued. General cleaning includes cleaning using ammonia and aqueous hydrogen peroxide, cleaning using hydrochloric acid and aqueous hydrogen peroxide, and the like.

  Next, a surface protective film (antireflection film) 7 is formed on the diffusion layer 5 formed on the surface (light receiving surface) of the separation substrate (FIG. 1 (f)). The film types include silicon oxide film, silicon nitride film, aluminum oxide, titanium dioxide film, zinc oxide film, tin oxide film, etc., but the appropriate film type varies depending on the conductivity type of the diffusion layer, and it is highly functional. In order to function as an antireflection film, the order of film formation and the film thickness are different. For example, by forming a silicon nitride film on the phosphorus diffusion layer using a direct plasma CVD apparatus having a frequency of 250 kHz, a surface protective film and antireflection film can be obtained. The film thickness of the silicon nitride film at this time is suitably 70 to 100 nm because it also serves as an antireflection film. In addition to the above, the formation method includes a remote plasma CVD method, a coating method, a vacuum deposition method, and the like. From an economical viewpoint, it is preferable to form the silicon nitride film by the plasma CVD method. Furthermore, if a film having a refractive index between 1 and 2, such as a magnesium difluoride film, is formed on the antireflection film so that the total reflectance is minimized, the reflectance is further reduced, and the generated current is reduced. Density increases.

  Next, a light receiving surface electrode 8 and a back surface electrode 9 can be formed by applying an electrode paste containing silver or aluminum on the light receiving surface and the back surface using a screen printer or the like and baking it with a predetermined thermal profile (FIG. 1 ( g)). Electrode formation includes a vacuum deposition method, a sputtering method, and the like, and is possible without using only the screen printing method. At this time, the electrode pattern formed on the light receiving surface side is generally a structure composed of finger electrodes composed of a plurality of substantially parallel thin wire electrodes and several relatively thick bus bar electrodes substantially orthogonal thereto, The finger electrodes preferably have a width of about 100 to 200 μm and the interval of about 1.5 to 2.5 mm, and the bus bar electrodes preferably have a width of about 1 to 3 mm and about 1 to 4 with respect to the substrate.

  As described above, the method for manufacturing a semiconductor device according to the present invention has been described by taking a solar cell as an example. However, the present invention is not limited to this, and the present invention is not limited to this. Can be applied.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not restrict | limited to the following Example.

[Example 1]
A single crystal silicon ingot having a phosphorus-doped n-type, a specific resistance of 1 to 2 Ω · cm, and a plane orientation (100) is pulled up by CZ method and cylindrically ground so that the diameter becomes 201 mmφ. The ingot surface was etched by several μm using a mixed acid solution of hydrofluoric acid and nitric acid.
Next, a silicon ingot having a length of 30 cm was prepared, and sliced using a multi-wire saw so that the substrate thickness after slicing was 225 μm. At this time, the kerf thickness per slice in the slicing process was 175 μm, and the kerf ratio was 43.8%.

Subsequently, mixed acid etching and hydrogen ion implantation were performed under the following conditions. First, etching with a mixed acid of hydrofluoric acid and nitric acid was performed to obtain a substrate thickness of 215 μm. Subsequently, hydrogen ions were implanted so that the average implantation depth of hydrogen ions was 107.5 μm and the implantation dose at the average implantation depth of hydrogen ions was 8 × 10 ¹⁶ cm ⁻² .

  Next, it was immersed in a 40% by mass sodium hydroxide aqueous solution, the damaged layer was removed by etching, and a random texture was formed on both sides by a wet etching method in which it was immersed in an aqueous solution in which isopropyl alcohol was added to 1-5% by mass sodium hydroxide. The substrate thickness after texture formation was 200 μm.

  A coating agent containing boron was spin-coated on both surfaces of the substrate and baked at 80 ° C. for 3 minutes. This was grooved in a quartz boat, inserted into a diffusion furnace heated to 600 ° C., heated and held at 990 ° C. for 20 minutes, thereby performing separation heat treatment and diffusion heat treatment at the same time. The substrates were separated without problems on the hydrogen ion implantation surface, and each of the two separated substrates had a thickness of 100 μm.

The two separated substrates thus obtained were subjected to junction separation by etching the entire back surface with a mixed acid solution of hydrogen fluoride and nitric acid by several μm using a wet etching junction separation apparatus.
Next, after removing the boron glass layer formed on the surface side (light-receiving surface side) with hydrofluoric acid, it is washed with a mixed solution of ammonia and hydrogen peroxide solution, and a mixed solution of hydrochloric acid and hydrogen peroxide solution and dried. It was.

Thereafter, using a direct plasma CVD apparatus having a frequency of 250 kHz, silicon nitride films having a thickness of about 100 nm were formed on both surfaces of the substrate in an atmosphere at 450 ° C.
Finally, using a screen printer, the electrode paste containing silver is printed on both sides of the substrate, dried, and fired at 800 ° C. with a firing profile having a peak for 10 seconds. Formed.

[Comparative Example 1]
A single crystal silicon ingot having a phosphorus-doped n-type, a specific resistance of 1 to 2 Ω · cm, and a plane orientation (100) is pulled up by CZ method and cylindrically ground so that the diameter becomes 201 mmφ. The ingot surface was etched by several μm using a mixed acid solution of hydrofluoric acid and nitric acid.
Next, a silicon ingot having a length of 30 cm was prepared and sliced using a multi-wire saw so that the substrate thickness after slicing was 115 μm. At this time, the kerf thickness per slice in the slicing process was 175 μm, and the kerf ratio was 60.3%.

  Next, it was immersed in a 40% by mass sodium hydroxide aqueous solution, the damaged layer was removed by etching, and a random texture was formed on both sides by a wet etching method in which it was immersed in an aqueous solution in which isopropyl alcohol was added to 1-5% by mass sodium hydroxide. The substrate thickness after texture formation was 100 μm.

  A coating agent containing boron was spin-coated on the light-receiving surface side of the substrate and baked at 80 ° C. for 3 minutes. This was grooved in a quartz boat, inserted into a diffusion furnace heated to 600 ° C., heated and held at 990 ° C. for 20 minutes to perform diffusion heat treatment.

The entire surface of the back surface of the substrate was etched by several μm with a mixed acid solution of hydrogen fluoride and nitric acid, using a wet etching bonding / separation device, to perform bonding separation.
Next, after removing the boron glass layer formed on the surface side (light-receiving surface side) with hydrofluoric acid, it is washed with a mixed solution of ammonia and hydrogen peroxide solution, and a mixed solution of hydrochloric acid and hydrogen peroxide solution and dried. It was.

Thereafter, using a direct plasma CVD apparatus having a frequency of 250 kHz, silicon nitride films having a thickness of about 100 nm were formed on both surfaces of the substrate in an atmosphere at 450 ° C.
Finally, using a screen printer, the electrode paste containing silver is printed on both sides of the substrate, dried, and fired at 800 ° C. with a firing profile having a peak for 10 seconds. Formed.

Evaluation of Solar Cell Characteristics A solar cell of 156.5 mm square produced in Example 1 and Comparative Example 1 was solar simulator (light intensity: 1 kW / m ² , spectrum: AM1.5 global in an atmosphere at 25 ° C. The current-voltage characteristics were measured under
Table 1 shows the number of substrates after slicing, the number of solar cells, and the processing yield after slicing obtained in Example 1 and Comparative Example 1. Table 2 shows the average values of various characteristics of the solar cells obtained in Example 1 and Comparative Example 1.

※１：実施例１は、スライス法及びイオン注入分離法により基板を作製したため、
「スライス後加工歩留り＝得られた太陽電池セル枚数÷（スライス後基板枚数×２）」とした。
※２：比較例１は、スライス法のみで基板を作製したので、
「スライス後加工歩留り＝得られた太陽電池セル枚数÷スライス後基板枚数」とした。
スライス後基板枚数に対する太陽電池セル枚数の減少分は、上記太陽電池セル製造工程におけるワレ不良による。

* 1: In Example 1, since the substrate was fabricated by the slice method and the ion implantation separation method,
“Processing yield after slicing = number of obtained solar cells ÷ (number of substrates after slicing × 2)”.
* 2: In Comparative Example 1, the substrate was produced only by the slicing method.
“Processing yield after slicing = number of solar cells obtained ÷ number of substrates after slicing”.
The decrease in the number of solar cells relative to the number of substrates after slicing is due to cracking defects in the solar cell manufacturing process.

  From Table 1, it can be seen that the crystal loss was reduced in Example 1 compared with Comparative Example 1, and the productivity and yield were improved.

  From Table 2, it can be seen that in Example 1, a photoelectric conversion efficiency equal to or higher than that in Comparative Example 1 was obtained.

1 Semiconductor substrate (original substrate)
1 'Semiconductor substrate (separation substrate)
2 Ion implantation layer 3 Texture 4 Separation surface 5 Dopant diffusion layer 6 Etching surface 7 Antireflection film 8 Light receiving surface (front surface) electrode 9 Non-light receiving surface (back surface) electrode

Claims (8)

A step of forming an ion implantation layer by implanting hydrogen ions or rare gas ions from a surface of the original substrate, which is a semiconductor substrate having a thickness of 100 to 400 μm, which has been planarized, to a predetermined depth from the surface of the original substrate. ,
Thereafter, the original substrate is heat-treated in the presence of a dopant having a conductivity type different from that of the original substrate to separate the original substrate in the ion-implanted layer and to have two separated substrates having a cross section substantially parallel to the original substrate surface. with obtaining, the step of the two separate substrates each of the original substrate surface or rear surface is a surface of the dopant forming dopant diffusion layer is diffused, and the dopant diffusion layer electrically to said separating substrate surface The manufacturing method of the semiconductor device characterized by including the process of forming the electrode to connect electrically.   Further, after the step of forming the ion-implanted layer, before the step of obtaining the two separated substrates by the heat treatment, a texture composed of fine irregularities having a height of 1 to 20 μm is formed on the front and back surfaces of the original substrate. The method for manufacturing a semiconductor device according to claim 1, further comprising a step. 3. The method of manufacturing a semiconductor device according to claim 2, wherein the thickness of the original substrate is the sum of the thicknesses of the two separation substrates plus the substrate thickness lost due to the texture formation. .   The method of manufacturing a semiconductor device according to claim 1, wherein the semiconductor device is a solar battery cell.   The method for manufacturing a semiconductor device according to claim 4, wherein the diffusion heat treatment temperature is 800 to 1100 ° C.   Further, after the formation of the dopant diffusion layer, the method includes a step of etching at least a cross section of the separation substrate. The etching removes the dopant diffusion layer formed on the cross section of the separation substrate and removes damage on the cross section. The method for manufacturing a semiconductor device according to claim 1.   The semiconductor device manufacturing method according to claim 1, wherein the semiconductor device is a power device.   The method of manufacturing a semiconductor device according to claim 7, wherein the diffusion heat treatment temperature is 800 to 1350 ° C.

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