JP2006216762A - Semiconductor element, its manufacturing method and inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor element inspection method which is capable of actualizing and analyzing the short circuit part of a semiconductor element, and to provide a method of manufacturing the semiconductor elements with higher yield. <P>SOLUTION: The semiconductor element is composed of a first electrode layer, a semiconductor layer, and a second electrode layer successively laminated in this sequence on a substrate. A metal oxide is electrochemically and selectively separated out in a water solution only at the short circuit part of the semiconductor layer, and then the metal oxide is substantially removed. Or, the metal oxide is separated out only at the short circuit of the semiconductor layer, then a second electrode is deposited, and a part of the second electrode deposited on the metal oxide is removed together with most of the metal oxide. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor element, particularly a photovoltaic element such as a solar cell or a photosensor, and a method for forming and inspecting the semiconductor element, and in particular, by electrochemically depositing a metal oxide from an aqueous solution on a short-circuit portion of a semiconductor layer. The present invention relates to a method for inspecting a semiconductor element that makes a short-circuited portion of a semiconductor element apparent and enables analysis of the short-circuited part, and a technique for increasing the yield in the manufacture of semiconductor elements by removing the influence of the short-circuited part.

  Conventionally, photovoltaic devices using non-single-crystal silicon-based semiconductors are generally well known. As a typical example, a non-single crystal semiconductor film such as amorphous silicon having a pin or nip junction parallel to the film surface is deposited on a stainless steel substrate by a sputtering method such as ZnO and Ag. Is deposited using a plasma CVD method or the like, and a light incident side electrode made of a light-transmitting conductive oxide, typically ITO or SnO2, is laminated, or a light incident side electrode such as SnO2 on a glass substrate. Then, a non-single-crystal semiconductor film is deposited, and a back reflective layer made of ZnO, Ag, or the like is deposited. In particular, these non-single-crystal silicon photovoltaic elements can be made very thin compared to single-crystal photovoltaic elements, so the material cost is low and they are expected to be further developed as power solar cells in the future. Has been.

  Photovoltaic elements are devices that convert incident light energy into electrical energy. Among them, solar cells convert sunlight into electrical energy, and are characterized by efficiently converting light in a wide wavelength range. It is an electromotive force element. One of the most important characteristics required for solar cells is high conversion efficiency. In order to achieve this purpose, it is necessary to absorb light without waste over a wide wavelength range. As one of the methods, it is known to have a stacked structure in which a plurality of photovoltaic elements having semiconductor layers having different band gaps as photoactive layers are stacked. This laminated photovoltaic element (hereinafter referred to as a laminated photovoltaic element) has a photovoltaic element with a relatively large band gap on the light incident side to absorb light having a short wavelength with a large energy. A photovoltaic device having a relatively small band gap is disposed below, and long-wavelength light having a low energy transmitted through the upper device is absorbed to efficiently absorb and use light in a wide wavelength range. The important point here is that each element receives light in a wavelength region suitable for the light absorption characteristics of the photovoltaic elements provided on the light incident side and the photovoltaic elements provided below the photovoltaic elements. It is necessary to introduce. This is because each photovoltaic device has a different wavelength range in which incident light can be used depending on the band gap of the semiconductor used in the photoactive layer. That is, photons having energy smaller than the band gap are not absorbed by the semiconductor and cannot be used. Photons with energy larger than the band gap are absorbed, but energy exceeding the band gap is lost and cannot be used. In a stacked photovoltaic device, the light incident side device can absorb more light in the short wavelength region, and the photovoltaic device below it can selectively absorb only light in the long wavelength region more selectively. Conversion efficiency is improved. As one means for solving this problem, a method is known in which a transparent conductive interface layer made of a metal oxide is provided between two photovoltaic elements and used as a selective reflection layer. For example, Patent Document 1 discloses a method in which a conductive layer that reflects light having a short wavelength and transmits light having a long wavelength is provided between elements. Patent Document 2 discloses a method in which light scatterers are provided between stacked photovoltaic layers, and these light scatterers increase the degree of scattering of incident light as it goes deeper into the apparatus. ing.

  As described above, the non-single-crystal silicon semiconductor layer as described above is an ultra-thin film having a thickness of 100 nm to several μm, and when cracks or cracks occur due to thermal stress in the semiconductor formation process or external stress in the processing process, etc. The 1st electrode layer and the 2nd electrode layer may be in a short circuit state. In addition, when fine dust adheres to the substrate deposition surface in the semiconductor layer forming process, the fine dust adhering portion becomes a pinhole or the like where the semiconductor layer is not formed, and the first electrode layer and the second electrode layer may be short-circuited. . When there are many short-circuit portions in the photovoltaic element, there arises a problem that the photovoltaic power cannot be extracted effectively. Conventionally, various countermeasures (optimization and cleaning of the semiconductor formation process) have been taken to deal with this problem. However, if the photovoltaic device is enlarged, a short circuit will occur probabilistically. This is a factor that decreases the yield in mass production of power elements. In order to solve this problem, there is a method of selectively etching a short-circuited surface electrode and removing the short-circuited portion by immersing the device in an electrolytic solution and energizing the short-circuited portion after forming the photovoltaic device. It is described in Patent Document 3.

However, even if the selective etching is performed, the short-circuit state of the photovoltaic element cannot be completely repaired, and there is also a photovoltaic element in which the short-circuited portion remains, and the yield in manufacturing the element is not necessarily perfect. I could n’t go up to the level. By pursuing the cause of the short circuit of the photovoltaic element and taking measures against it, the yield in the production of the element can be increased. Actually, since the short circuit portion is not visible, the cause of the short circuit portion is not clear. If the short-circuited portion can be realized or visualized, the cause of the short-circuit can be pursued. Until now, there are various methods for revealing and detecting defects such as a short-circuit portion of a semiconductor element, which are disclosed in Patent Document 4 and the like. The main items are listed below.
(1) Liquid crystal method: A liquid crystal that undergoes phase transition at a constant temperature is used, and a liquid crystal formed as a sensor on a semiconductor is phase-transformed by heat generation due to a short-circuit current. High sensitivity with a small short-circuit current, but voltage must be continuously applied during inspection. The resolution is several tens of μm.
(2) Fluorinert method, alcohol method: Using a low-boiling point fluorinate or low-melting alcohol as a semiconductor, the florinate or alcohol is vaporized by heat generation due to a short-circuit current to generate bubbles. Special equipment is required and the resolution is limited to the size of the bubble and is a few hundred μm.
(3) Infrared camera method: An infrared camera captures infrared rays generated by heat generated by a short-circuit current. Since it is infrared rays due to heat generation, it is difficult to provide contrast, and the resolution is several hundred μm to several mm, which is not suitable for microanalysis. In addition, current must continue to flow during the inspection, and the short-circuited portion may be altered by heat generated by the current.
(4) Copper decoration method: Copper is electrochemically deposited on the defect by a short-circuit current. The resolution is from several μm to several tens of μm.
(5) Electrodeposition method: An electrodeposition paint which is an insulating polymer compound is electrodeposited by a short circuit current.

  The principle of copper decoration is as follows. A semiconductor element is placed on an anode electrode, a cathode electrode serving as a counter electrode is placed at a distance of about 5 mm, and immersed in an electrolytic solution containing copper ions. In the case where a short-circuit portion exists in the semiconductor element, the current flows intensively there, and copper is deposited. This copper decorating enlarges the short-circuited portion, which was not visible at all, to a size of about several μm to 1 mm, so that visual confirmation is possible. However, with copper decoration, it can be said that it is an optimal method for inspecting the number of short-circuited parts. However, when copper is removed with a cloth or the like in order to analyze the structure of the copper-deposited part (short-circuited part), the deposited copper Because it is soft and fragile, it disappears without a trace. Therefore, there is a problem that it becomes impossible to specify where the decorated part is.

In the electrodeposition method, as disclosed in Patent Document 5, the semiconductor element is immersed in an electrodeposition paint, and an appropriate voltage is applied to the semiconductor element to apply only the low resistance portion of the semiconductor element. By depositing the electrodeposition paint, the electric resistance of the low resistance portion becomes sufficiently high. Therefore, the electrodeposition method is effective not only as a defect inspection method for semiconductor elements such as photovoltaic elements but also as a method for removing a short circuit. However, in order to analyze the structure of the part where the electrodeposition paint is attached (short-circuit part), the electrodeposition paint is polished and removed, and there is a risk that the short-circuit part will be destroyed together with the electrodeposition paint. . In addition, since the electrodeposition method requires an applied voltage of 2 V or more due to its principle, when a voltage is applied in the forward direction in a photovoltaic element, only the low resistance portion of the element can be selectively electrodeposited. There was a problem that it would be difficult.
JP-A-63-77167 Japanese Patent No. 3203106 Japanese Patent Publication No. 1-286371 JP 07-270369 A JP 06-14648 Patent Publication 2000-133829

  For detection of short-circuit defects in semiconductor devices such as photovoltaic devices, it is desirable to have the same resolution as the liquid crystal method, copper decoration method, and electrodeposition method. That is, it is required that the manifestation result does not change with time, and that the structure analysis of the short-circuited portion is possible even after the manifestation result is removed.

  Further, there is a demand for a method of selectively insulating only a short-circuit portion of a semiconductor element such as a photovoltaic element and sufficiently extracting the performance of the element.

  Furthermore, in a stacked photovoltaic element that is used as a selective reflection layer by providing an interface layer made of a transparent conductive layer between two photovoltaic elements, if there is a short-circuited portion in one of the photovoltaic elements In some cases, a short-circuit current diffuses inside the interface layer, which is a transparent conductive layer, and excellent device characteristics cannot be obtained. In order to avoid the influence of the short-circuit current, it is conceivable that the interface layer is provided and then immersed in the electrolytic solution, and the interface layer in the short-circuit portion is removed by etching. However, if the interface layer is thick, the etching time is Longer and less productive. In addition, the effect of etching also appears on the part that is not short-circuited, and the original purpose of effectively using light cannot be achieved.

  An object of the present invention is to provide a method for inspecting a semiconductor element that can clearly detect a short-circuit portion, for example, an abnormal object that causes a short-circuit current. Furthermore, the present invention provides a new method for increasing the yield of semiconductor elements by effectively removing the short-circuit portion and making it non-conductive. Another object of the present invention is to provide a method for expressing high conversion efficiency in a stacked semiconductor element provided with an interface layer without being affected by a short circuit portion of the semiconductor layer.

  The semiconductor inspection method of the present invention is a method for inspecting a semiconductor element in which at least a semiconductor layer is laminated on a substrate, and selectively deposits a metal oxide from an aqueous solution only on a short-circuit portion of the semiconductor layer. A method for inspecting a semiconductor device, comprising: a step of removing the metal oxide; and a step of substantially removing the metal oxide.

  The semiconductor element and the method for forming the same according to the present invention are a semiconductor element in which at least a first electrode layer, a semiconductor layer, and a second electrode layer are laminated in this order on a substrate, and the periphery of the short-circuit portion of the semiconductor layer A ring-shaped metal oxide electrochemically deposited from an aqueous solution is deposited on the outer surface of the ring-shaped metal oxide; a second electrode is deposited on the outside of the ring-shaped metal oxide in contact with the ring-shaped metal oxide; A semiconductor element in which the second electrode does not exist on the semiconductor layer surrounded by the oxide, and a method for forming the semiconductor element.

  Alternatively, a semiconductor element in which at least a first electrode layer, a first semiconductor layer, a transparent conductive interface layer, a second semiconductor layer, and a second electrode layer are sequentially stacked in this order on a substrate, the first semiconductor An annular metal oxide electrochemically deposited from an aqueous solution is deposited around the short-circuit portion of the layer, and the interface layer is not deposited on the semiconductor layer in the portion surrounded by the annular metal oxide A semiconductor element and a method for forming the same.

  By using the present invention, it is possible to detect a short-circuit defect portion of a semiconductor element, particularly a photovoltaic element, by an inexpensive and simple method of selectively depositing a metal oxide electrochemically only on the short-circuit portion of the semiconductor element. It becomes possible. Furthermore, it is possible to realize a photovoltaic device in which the upper electrode in the short-circuit portion is removed, and it is possible to improve the yield in the production of the photovoltaic device. In addition, it is possible to draw out high performance of a stacked photovoltaic element having a transparent conductive layer as an optical confinement layer as an interface layer.

  Patent Document 6 discloses that a metal oxide is deposited on a semiconductor layer from an aqueous solution by electrochemical means. If this technique is used, the metal oxide can be uniformly deposited on the semiconductor layer. However, at the initial stage of deposition, the deposition is limited only to the portion where the most current flows in the semiconductor layer. The present inventors have found that by adjusting the deposition conditions such as the voltage condition, it is possible to selectively deposit the metal oxide only in the short-circuit portion (FIG. 1 (a) and FIG. 2 ( a)). Furthermore, metal oxides such as zinc oxide have higher adhesion to the semiconductor layer than copper and are harder, so when a physical impact is applied, the portion in contact with the surrounding semiconductor layer is left in a ring shape, which is large. The portion is broken and substantially removed (FIG. 1B). That is, only the cyclic metal oxide centering on the short-circuited portion remains (FIG. 2D). According to the analysis by the present inventors, there were convex abnormal objects and concave abnormal objects at the center of the annular zinc oxide, that is, the center of the short-circuited portion. Such abnormal growth is considered to be the cause of the short circuit.

  A second electrode is formed on the semiconductor layer on which the metal oxide is deposited at the short-circuit portion by using a sputtering method or the like (FIG. 3A). Even if an attempt is made to form the second electrode with copper deposited on the short-circuited portion by the copper decoration method, the copper is easily removed, so only when the second electrode is deposited with copper deposited on the short-circuited portion. In some cases, the deposited copper is removed, the short-circuit portion is exposed, and the second electrode is deposited thereon. In the present invention, after the second electrode is formed on the deposited metal oxide, the second electrode can be removed together with the metal oxide by physical impact (FIG. 3B). That is, the second electrode at the short-circuit portion is removed, the short-circuit path is made nonconductive, and a semiconductor element that is not affected by the short-circuit current is completed. Furthermore, in the deposited metal oxide, the portion in contact with the semiconductor surface on the outer periphery of the deposited metal oxide remains in a ring shape with the short-circuit portion as the center. When this annular metal oxide has a higher resistance than the second electrode, diffusion of the short circuit current is suppressed, and a semiconductor element having a larger short circuit resistance can be obtained. On the other hand, in the semiconductor element obtained by the conventional short-circuit recovery method by selective etching of the second electrode, a short-circuit current slightly flows through the second electrode around the short-circuit portion. Although the thickness gradually decreases, it may remain without being completely removed. Therefore, the operation of the element may be affected by the flow of a short-circuit current. When the semiconductor element manufactured in the present invention is used, the second electrode is removed up to a certain range centered on the short-circuited portion, and the normal second electrode exists in the portion outside the certain range. It does not affect the electrical characteristics of the semiconductor element such as the conversion efficiency of the photovoltaic element.

  In the present invention, if necessary, an interface layer may be further formed on the semiconductor layer in which the metal oxide is deposited on the short-circuited portion (FIG. 4A). After forming the interface layer, the interface layer is removed together with the metal oxide by physical impact (FIG. 4B). Further, a semiconductor layer is formed thereon, and the second electrode is stacked, thereby completing a stacked photovoltaic element that uses the interface layer as a selective reflection layer. Since the interface layer is removed together with the metal oxide, the short-circuit current of the semiconductor layer in which the metal oxide is deposited in the short-circuit portion does not diffuse inside the interface layer. That is, a photovoltaic element having a voltage-current curve (FIG. 5 (a)) in which the short-circuit portion is made non-conductive with certainty and is not affected by the short-circuit current is realized. Here, when the interface layer in the short circuit portion is not removed, the effect of the short circuit current appears on the dark current and the photocurrent of the photovoltaic element (the portion 501 in FIG. 5B). Realization of the electromotive force element becomes difficult.

  Physical impact to remove metal oxides deposited on the short-circuited part is mechanical friction using cloth, brush, brush, etc., impact caused by fluid consisting of fluid, gas, powder, etc., adhesive tape Such as mechanical pulling such as peeling due to. Alternatively, the metal oxide may be destroyed in advance by pressing a pressure roller or the like against the semiconductor surface, and then removed by mechanical friction or impact by fluid. Further, when the semiconductor element has flexibility, it is also effective as a method for removing the metal oxide to give a warp or bend the semiconductor by combining rollers.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 6 is an example of a configuration diagram of an experimental apparatus for performing an electrodeposition process according to the present invention. Here, a semiconductor element is inspected and a semiconductor element is manufactured using this experimental apparatus.

[Configuration of experimental equipment]
In the experimental apparatus of FIG. 6, an electrodeposition bath 601 is held in a beaker 606, and a cathode 602 that is a cathode (−electrode) and an anode 603 that is an anode (+ electrode) are both immersed in the electrodeposition bath 601. The electrodeposited film is formed on the cathode 602 side. The beaker 606 is placed on the heating and stirring table 607, and the electrodeposition bath 601 is heated and kept warm by the heating and stirring table 607 in the range from room temperature to about 100 ° C. A magnetic stirrer 608 coated with Teflon (registered trademark) is placed on the bottom of the beaker 606, and the magnetic stirrer 608 stirs the electrodeposition bath 601 with the rotating magnetic field generated by the heating stirrer 607. The cathode 602 is an electrode through which current flows from the electrodeposition bath 601, and the reduction reaction proceeds mainly electrochemically. The anode 603 is an electrode from which current flows toward the electrodeposition bath 601, and the oxidation reaction proceeds mainly electrochemically. The distance between the anode and cathode electrodes is set to 0.5 cm to 7 cm. The power source 609 is connected to the cathode 602 on the negative side of the output terminal and connected to the anode 603 on the positive side of the output terminal, and uses a potentiostat for voltage control of the output or a galvanostat for current control. The anode (counter electrode) used in the present invention is the same as the metal constituting the deposited metal oxide or insoluble.

  The experimental apparatus having the above configuration is operated as follows to perform the electrodeposition process. An electrodeposition bath 601 of necessary components is prepared and filled in a beaker 606, and heating and stirring are caused. The cathode 602 and the anode 603 are set in the electrodeposition bath 601. When the temperature becomes constant, current or voltage is applied to the electrodes to start metal oxide electrodeposition. In order to accurately control the current value, it is preferable to mask the opposite side of the anode facing surface of the cathode 602 serving as a film formation substrate with a masking tape. After the electrodeposition is completed, the cathode 202 which is a film formation substrate is removed, washed with pure water, and dried in air or an oven. The surface of the sample thus obtained is observed with an electron microscope (SEM).

[Electrodeposition bath]
The electrodeposition bath used in the present invention can replenish nitrate ions, zinc ions, indium ions, and the like from different substances in addition to zinc nitrate or indium nitrate dissolved in water. Nitrate ions are not indispensable, and those containing carboxylate ions such as acetate ions, oxalate ions and formate ions are also possible. Nitrate ions are easy to use because of their good oxidation characteristics. Basically, it is important that the electrodeposition bath contains the metal to be deposited as a metal oxide as ions or complex ions. The deposition of zinc oxide needs to contain zinc ions or zinc complex ions, and the deposition of indium oxide needs to contain indium ions or indium complex ions. The concentration of the electrodeposition bath is such that it has a concentration that can contain a sufficient amount of metal ions or metal complex ions to precipitate, conversely, the concentration is excessively increased, the pH is inadvertently lowered, or Determined by taking into consideration that the anode and cathode will not be eroded due to excessive increase. Usually, the concentration is set in the range of 0.0001 mol / L to 0.5 mol / L. In a stable electrodeposition region, a small change in concentration does not significantly change the characteristics of the film to be electrodeposited. Additives can be added to the electrodeposition bath. For example, since saccharides have the effect of preventing abnormal growth, they are extremely preferable for stable metal oxide precipitation. Examples of the saccharide include sucrose, glucose, and dextrin. The addition amount of these additives is preferably 0.1 mg / L or more. The temperature of the electrodeposition bath varies depending on the substance contained in the electrodeposition bath and the metal oxide to be deposited. For example, 60 to 95 ° C is preferable for zinc oxide electrodeposited from zinc nitrate, and 25 to 60 ° C is preferable for indium oxide electrodeposited from indium nitrate, and zinc oxide electrodeposited from zinc acetate. In this case, the temperature is preferably 80 ° C. to 100 ° C. In general, it is preferable that the temperature of the zinc oxide electrodeposited from the zinc carboxylate is high.

[Metal oxide]
Examples of the metal oxide used in the present invention include zinc oxide (ZnO), indium oxide, and ITO (In2O3 + SnO2). The deposited portion is desirably 1 μm to 1 mm in size, and particularly preferably 1 μm to 100 μm. If the deposited portion is smaller than 1 μm, it is difficult to visually confirm the short-circuited portion. In addition, if the deposited portion is larger than 100 μm, it will affect the detection of the short-circuited portion, such as crushing in the middle of work or concealing other short-circuited portions due to large fragments. The size of the deposited portion of the metal oxide or the thickness of the metal oxide is substantially determined by the current density and the deposition time. The current necessary for the electrodeposition reaction is 0.1 to 100 mA / cm ² in terms of current density, but the current density and the deposition time are adjusted so that the metal oxide is selectively deposited only at the short-circuit portion. In order to adjust the current density, the voltage is changed, but if the semiconductor installed at the cathode has a diode characteristic like a photovoltaic element and the diode current flows in the forward direction, it is selectively applied only to the short-circuited part. In order to deposit the metal oxide, the voltage needs to be limited to a certain level.

〔semiconductor〕
The semiconductor used in the present invention serves as a cathode in an electrochemical deposition process and as a substrate for a film formed thereon. To fulfill these roles, it has chemical resistance such as insolubility and ionization in the electrodeposition bath, a high hydrogen overvoltage, a potential at which electrodeposition can be performed on the solution, and electrodeposition It is necessary to be able to pass a current that exchanges possible charges. As those satisfying these conditions, there are III-V group semiconductors such as InP and GaN, II-VI group semiconductors such as ZnS, and IV group semiconductors such as Si and Ge. In these, a dopant that controls p-type or n-type conductivity may be introduced. The crystallinity can be crystalline, polycrystalline, microcrystalline, amorphous, or a mixture thereof.

  The semiconductor may have a thickness that allows itself to stand alone, or may be formed as a thin film on an insulating substrate such as glass or a conductive substrate such as stainless steel (SUS). Examples of the former include InP, GaN, Si, and Ge mentioned above. These may be single crystals, but may be polycrystalline. Examples of the latter using an insulating substrate include amorphous, microcrystalline, or polycrystalline Si, SiGe, SiC formed on glass or ceramic. Examples of the latter using a conductive substrate include amorphous or microcrystalline or polycrystalline Si formed on a metal such as SUS, Al, Cu, Fe, Cr, or a PET film with a metal coating, Examples include SiGe and SiC thin film semiconductors. In the present invention, since the metal oxide is selectively deposited only on the short-circuit portion on the semiconductor, it is desirable that the amount of current flowing greatly differs between the short-circuit portion and the non-short-circuit portion in the semiconductor.

  Examples of the semiconductor element include a pin junction, a pn junction, a Schottky junction, and a heterojunction formed by stacking a p-type semiconductor, an i-type semiconductor, and an n-type semiconductor, and at least one of them. The above is laminated. As the semiconductor material, amorphous silicon, microcrystalline silicon, polycrystalline silicon, or an alloy thereof is used. In order to form these semiconductor layers, a high frequency (RF) CVD method, a very high frequency (VHF) CVD method, a microwave CVD method, and a heat ray (CAT) CVD method can be reduced in cost, and the area can be increased. It is preferred because it is easy. In a semiconductor element formed by stacking two or more junctions, a metal oxide such as ZnO or ITO may be used for the interface layer as the selective reflection layer. For example, a double-type laminated photovoltaic element of microcrystalline silicon and amorphous silicon using a ZnO interface layer or the like can be used.

  Next, examples of the present invention will be described.

Example 1
As an example of the present invention, a pin junction type microcrystalline silicon single cell as shown in FIG. 7 was attached to the cathode 602, and a short circuit portion was detected.
(1) First, a substrate 701 (width 356 mm × length 60 m) made of stainless steel 430 on a roll was subjected to cleaning with a surfactant and water, and dried to remove dirt and foreign matters on the surface.
(2) A first electrode 702 was deposited on the substrate 701 by a known roll-to-roll type sputtering apparatus using a back reflective layer Ag 702a having a thickness of 800 nm and a transparent conductive layer ZnO 702b having a thickness of 2 μm.
(3) Further, an n-type layer 703a made of an n-type amorphous silicon film, an i-type layer 703b made of an i-type microcrystalline silicon film, on the back reflective layer 702 by a roll-to-roll type plasma CVD apparatus, A p-type layer 703c made of a p-type microcrystalline silicon film was stacked to form a semiconductor layer 703.
(4) The stainless steel substrate on which the semiconductor layer 703 was formed was cut out in a size of 5 cm × 8 cm, and ZnO was deposited using an electrodeposition bath placed in a beaker. A 0.2 mol / l zinc nitrate aqueous solution was prepared for the electrodeposition bath, and 10 mg / l of dextrin was mixed and maintained at 80 ° C. for use. The voltage was 1.3V is applied, the current density of 4mA / cm ² (current 90mA area 22.6cm ^2), 10 min selectively precipitate the ZnO on the short-circuit path of the semiconductor layer.
(5) Thereafter, the surface of the semiconductor layer was lightly wiped with a dry cloth to remove the deposited ZnO, and then the removed ZnO was blown off by blowing compressed air. A sample was cut at an arbitrary place with a diameter of 7 mm, and SEM observation was performed.

  The observed SEM image is shown in FIG. ZnO was deposited only in the short-circuit portion (FIG. 2 (a)). Approximately 10 to 200 μm of ZnO was precipitated. An enlarged image of the deposited ZnO is shown in FIG. An enlarged image from the side is shown in FIG. ZnO was deposited in a dome shape, and its height was about the radius of the dome seen from above. It can also be seen that a slightly thinner ZnO grows in an annular shape around the dome. The cracks in the photograph are caused by bending the sample to make an angle during SEM observation. FIG. 2D shows a state where ZnO is removed. Since the thin annular ZnO around the dome remains, it can be seen that this is the place where the dome-shaped ZnO was deposited at the short-circuit portion. It can be seen that a convex protrusion remains in the center of the annular ZnO. It was derived from the above inspection that this protrusion is the cause of the short-circuit portion.

(Example 2)
In Example 1, the steps (1) to (4) were performed, and ZnO was deposited on the short-circuit path of the semiconductor layer, and a transparent conductive layer was further deposited as the second electrode. A power element can be formed.

(1) to (4) Same as Example 1.
(5) Twenty-five second electrodes 704 made of ITO (In ² O 3 + SnO 2) having a thickness of 80 nm and an area of 0.25 cm ² are formed on the semiconductor layer 703 by a batch type sputtering apparatus.
(6) Further, an Au grid electrode 705 having a thickness of 300 nm and a thickness of 50 μm is formed on the second electrode 704 by a batch type electron beam evaporation apparatus.
(7) Thereafter, the surface of the second electrode is gently wiped with a dry cloth, so that ZnO deposited on the short-circuited portion and ITO deposited thereon are removed.
(8) Connect the positive electrode and the grid electrode 705, connect the negative electrode to the substrate 701, measure the voltage-current characteristics in the dark state, and obtain the short-circuit resistance RshDark from the slope near the origin.

(Comparative Example 1)
In the first embodiment, the steps (1) to (3) are performed, and the steps (5), (6), and (8) of the second embodiment are performed without depositing ZnO on the short-circuit path. .

(Comparative Example 2)
The same process as that of Example 2 is performed except that the process (7) is not performed.

  In the photovoltaic device produced in this example, RshDark is considerably large because ZnO deposited on the short-circuited portion and ITO deposited thereon are removed. Even when compared with the photovoltaic elements produced in Comparative Example 1 and Comparative Example 2, there is a marked difference.

(Example 3)
After carrying out the steps (1) to (3) in Example 1, ZnO is deposited on the short-circuit path of the semiconductor layer by using a roll-to-roll type electrodeposition apparatus, and further, By depositing a transparent conductive layer as two electrodes and further forming a semiconductor layer, a more efficient photovoltaic element (FIG. 7) can be formed.

(1) to (3) Same as Example 1.
(4) ZnO is deposited on the semiconductor layer 803 on the short-circuit path of the semiconductor layer using a known roll-to-roll type electrodeposition apparatus.
(5) Further, an interfacial layer 804 made of ITO having a thickness of 600 nm is formed thereon by a roll-to-roll type sputtering apparatus.
(6) After the interface layer 804 is formed, friction is applied to the surface with a synthetic resin brush, and the ITO formed thereon is removed together with ZnO deposited on the short-circuited portion.
(7) Further, an n-type layer 805a made of an n-type amorphous silicon film and an i-type film are formed by an apparatus similar to the roll-to-roll type plasma CVD apparatus used in step (3) of Example 1. An i-type layer 805b made of an amorphous silicon film and a p-type layer 805c made of a p-type microcrystalline silicon film are stacked to form a semiconductor layer 805.
(8) On the semiconductor layer 805, 25 second electrodes 806 made of ITO having a thickness of 80 nm and an area of 0.25 cm ² are formed by a batch type sputtering apparatus.
(9) Further, an Au grid electrode 807 having a thickness of 300 nm and a thickness of 50 μm is formed on the second electrode 806 by a batch type electron beam evaporation apparatus.
(10) Connect the positive electrode and the grid electrode 807, connect the negative electrode to the substrate 801, measure the voltage-current characteristics in the dark state, and obtain the conversion efficiency and short-circuit resistance RshDark of the photovoltaic element.

(Comparative Example 3)
ZnO is not deposited on the short-circuited part in step (4), and step (6) is omitted. Otherwise, a photovoltaic element is formed in the same manner as in Example 3, and the conversion efficiency and RshDark are measured.

(Comparative Example 4)
A photovoltaic element is formed in the same manner as in Example 3 except that the step (6) is not performed, and the conversion efficiency and RshDark are measured.

  The voltage-current curve of the photovoltaic element obtained in Comparative Example 3 or Comparative Example 4 has a shape as shown in FIG. 5B, where the dark current is large and RshDark is low. Further, the conversion efficiency is influenced by this, and the effect of inserting an interface layer that performs selective reflection cannot be obtained. The voltage-current curve of the photovoltaic element that can be produced in this example has a shape as shown in FIG. 5A, and high conversion efficiency is obtained.

It is a cross-sectional schematic diagram of the inspection method of the semiconductor element concerning this invention. It is a SEM photograph which shows the test result of the semiconductor element which is one Example of this invention. (A) The surface of the microcrystalline silicon photovoltaic device in which zinc oxide is deposited on the short-circuited portion, (b) an enlarged image of zinc oxide deposited on the short-circuited portion, (c) from the side of the zinc oxide deposited on the short-circuited portion Enlarged image, (d) State where deposited zinc oxide is removed It is a cross-sectional schematic diagram which shows the structure of the photovoltaic element concerning this invention. It is a cross-sectional schematic diagram which shows the structure of the photovoltaic element which has an interface layer concerning this invention. It is a voltage-current curve of the photovoltaic device concerning this invention. It is a block diagram of the manufacturing apparatus which performs the electrodeposition process which shows embodiment. It is a section schematic diagram showing layer composition of a photovoltaic device concerning the present invention. It is a section schematic diagram showing layer composition of a photovoltaic device which has an interface layer concerning the present invention.

Explanation of symbols

101, 301, 401 Substrate 102, 302 Semiconductor layer 103, 303, 403 Short circuit path 104, 304, 404 Metal oxide 104, 305, 408 Second electrode 105, 306, 406 Trace of metal oxide taken 402 First semiconductor Layer 407 Second semiconductor layer 405 Interface layer 601 Electrodeposition bath (aqueous solution)
602 Cathode as negative electrode (-electrode) 603 Anode as positive electrode (positive electrode) 604, 605 Clip 606 Beaker 607 Heating and stirring device 608 Magnetic stirrer 609 Power supply 701, 801 SUS substrate 702, 802 First electrode 702a, 802a Back surface reflection Layer 702b, 802b transparent conductive layer 703 semiconductor layer 803 first semiconductor layer 703a, 803a, 805a n-type amorphous silicon layer 703b, 803b i-type microcrystalline silicon layer 805b i-type amorphous silicon layer 703c, 803c, 805c p Type microcrystalline silicon layer 804 interface layer 805 second semiconductor layer 704,806 second electrode 705,807 grid electrode

Claims (5)

  A method for inspecting a semiconductor device in which at least a semiconductor layer is laminated on a substrate, the step of selectively depositing a metal oxide from an aqueous solution only on a short-circuit portion of the semiconductor layer, and the metal oxide And a step of substantially removing the semiconductor element.   A semiconductor element in which at least a first electrode layer, a semiconductor layer, and a second electrode layer are laminated in this order on a substrate, and an annular metal oxide electrochemically deposited from an aqueous solution around a short-circuit portion of the semiconductor layer A second electrode is deposited on the outer side of the annular metal oxide so as to be in contact with the annular metal oxide, and on the portion of the semiconductor layer surrounded by the annular metal oxide. Is a semiconductor device, wherein the second electrode is not present.   A semiconductor element in which at least a first electrode layer, a first semiconductor layer, a transparent conductive interface layer, a second semiconductor layer, and a second electrode layer are sequentially stacked on a substrate in this order, A ring-shaped metal oxide electrochemically deposited from an aqueous solution is deposited around the short-circuit portion, and the interface layer is not deposited on the semiconductor layer in the portion surrounded by the ring-shaped metal oxide. A featured semiconductor element.   A method for forming a semiconductor device comprising a step of laminating at least a first electrode layer, a semiconductor layer, and a second electrode layer in this order on a substrate, wherein a metal oxide is selectively formed from an aqueous solution only at a short-circuit portion of the semiconductor layer. Depositing a second electrode on the semiconductor layer and the metal oxide layer, and substantially removing the metal oxide and depositing the second electrode on the metal oxide. And a step of removing the electrode.   A method of forming a semiconductor element, comprising: laminating at least a first electrode layer, a first semiconductor layer, a transparent conductive interface layer, a second semiconductor layer, and a second electrode layer in this order on a substrate, A step of selectively depositing a metal oxide from an aqueous solution selectively only on a short-circuit portion of one semiconductor layer; and depositing the interface layer on the first semiconductor layer and the metal oxide; And a step of removing the interface layer deposited on the metal oxide.

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