Semiconductor manufacturing method and semiconductor manufacturing device

Abstract

A semiconductor manufacturing method using a semiconductor manufacturing device (100), comprising: a configuration step, in which an anode (2) for performing an oxidation reaction is configured at one end of a substrate (1) containing aluminum oxide, and a cathode (3) for performing a reduction reaction is configured at the other end of the substrate (1); a heating step, in which the substrate (1) is heated to melt in a state where the anode (2) is in contact with one end of the substrate (1) and the cathode (3) is in contact with the other end of the substrate (1); a molten salt electrolysis step, in which a current is passed between the anode (2) and the cathode (3) during the entire period or a part of the period when at least a part of the substrate (1) is melted to perform molten salt electrolysis; and a semiconductor forming step, in which the substrate (1) is cooled after the molten salt electrolysis step to form a p-type aluminum oxide semiconductor layer and an n-type aluminum oxide semiconductor layer.

Description

Technical Field

[0001] The present invention relates to a semiconductor manufacturing method and a semiconductor manufacturing device. Background Art

[0002] In the past, in the field of semiconductors, especially in the field of power semiconductors, high power, high withstand voltage, high temperature operation and high frequency were required. Among these requirements, high withstand voltage has become a particularly important issue. Therefore, wide bandgap semiconductors with a larger bandgap than existing silicon-based semiconductors are urgently desired. In addition, in the field of primary batteries or secondary batteries, i.e. semiconductor batteries, it is also expected that semiconductor positive electrode materials and semiconductor negative electrode materials that can increase the electromotive force and storage capacity of semiconductor batteries will appear.

[0003] Here, while the band gap of silicon (Si) is 1.1 eV, the band gap of wide band gap semiconductors such as silicon carbide (SiC) is 3.3 eV and the band gap of gallium nitride (GaN) is 3.4 eV.

[0004] In recent years, the development of wide bandgap semiconductors with larger band gaps has been promoted. For example, diamond (C) with a band gap of 5.5 eV has attracted attention as a material for wide bandgap semiconductors. However, since diamond itself is not a semiconductor, ion implantation must be performed to form donor energy levels or acceptor energy levels. This ion implantation of diamond requires high temperature and high pressure, so there is a problem that it cannot be easily performed.

[0005] On the other hand, aluminum oxide has a band gap of 8.8 eV, which is attractive if it can be used as a wide-gap semiconductor material. However, it has been difficult to form donor or acceptor levels within the band gap of aluminum oxide. In particular, it is difficult to form acceptor levels that become p-type semiconductors. Therefore, although aluminum oxide can be used as an extremely excellent insulator with high reliability, it is difficult to form a p-type semiconductor using aluminum oxide and a pn junction using aluminum oxide.

[0006] Here, the present inventors have conducted detailed studies on a semiconductor layer using aluminum oxide as a base material and a method for producing the semiconductor layer as described in Patent Document 1.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1 International Publication No. 2016 / 175251 Summary of the invention

[0010] Problems to be solved by the invention

[0011] After inventing the invention described in Patent Document 1, the present inventors conducted further research and obtained the following results: that is, by applying a high voltage of about 10 to 60V between the anode and the cathode to ignite, a semiconductor layer using aluminum oxide and an element using a pn junction formed on the semiconductor layer can be manufactured.

[0012] However, the size of a semiconductor layer actually manufactured by sparking is about 1 μm (0.5 to 2 μm), which is too small to be actually used as a device.

[0013] Therefore, the present inventors use a scanning method to perform multiple sparkings to achieve enlargement of the semiconductor layer.

[0014] However, in this method, the semiconductor characteristics of the product differ at each ignition point, and the product as a whole does not have stable semiconductor characteristics.

[0015] In addition, a manual prober with a probe having a tip diameter of about 20 μm is used to realize the enlargement of the semiconductor layer. In this case, the area actually used to form the semiconductor layer is small, and the actual size is also about 5 μm. The formed semiconductor layer does not reach the size of a practical scale, and the electrical characteristics cannot be measured.

[0016] In addition, in order to measure the electrical characteristics of the semiconductor layer by using the Hall measurement method, it is necessary to form a semiconductor layer of about 20 μm or more, and to perform microfabrication on the four terminals on the semiconductor layer. Furthermore, in practical use, a semiconductor layer of more than 1 mm is required. As described above, there is a problem that it is technically difficult to achieve a large-scale semiconductor layer using aluminum oxide as a substrate.

[0017] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductor manufacturing method and a semiconductor manufacturing apparatus capable of increasing the size of a semiconductor layer using aluminum oxide as a substrate.

[0018] Technical means of solving problems

[0019] In order to solve the above-mentioned problem, a semiconductor manufacturing method according to one embodiment of the present invention is formed, and is characterized in that it includes: a configuration step, in which an anode for undergoing an oxidation reaction is configured at one end of a substrate comprising aluminum oxide, and a cathode for undergoing a reduction reaction is configured at the other end of the substrate; a heating step, in which the substrate is heated to melt while the anode is in contact with one end of the substrate and the cathode is in contact with the other end of the substrate; a molten salt electrolysis step, in which a current is passed between the anode and the cathode during the entire period or a part of the period in which at least a part of the substrate is melted to perform molten salt electrolysis; and a semiconductor formation step, in which the substrate is cooled after the molten salt electrolysis step to form a p-type aluminum oxide semiconductor layer and / or an n-type aluminum oxide semiconductor layer.

[0020] Effects of the Invention

[0021] According to the present invention, it is possible to increase the size of a semiconductor layer having aluminum oxide as a base material. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a diagram showing the arrangement structure of a semiconductor manufacturing apparatus and units in the first embodiment.

[0023] Figure 2 This is a diagram showing a semiconductor layer formed when the amount of electricity during power supply is small in Embodiment 1.

[0024] Figure 3 This is a diagram showing a semiconductor layer having a pn junction formed therein in the first embodiment.

[0025] Figure 4 This is a diagram showing a semiconductor layer formed when a large amount of electricity is applied during power supply in the first embodiment.

[0026] Figure 5 This is a diagram showing a method for forming an aluminum oxide semiconductor layer by laser irradiation in the first embodiment.

[0027] Figure 6 This is a diagram showing a state where the base material in the first embodiment is at or above the melting point of molten salt electrolysis.

[0028] Figure 7 This is a diagram showing a state near a melting point during formation of a semiconductor layer in the first embodiment.

[0029] Figure 8 This is a diagram showing a state near room temperature during formation of a semiconductor layer in the first embodiment.

[0030] Fig. 9 This is a flowchart showing the processing procedure of the semiconductor manufacturing method in the first embodiment.

[0031] Fig.10 This is a diagram showing the arrangement structure of a semiconductor manufacturing apparatus and units in the second embodiment.

[0032] Fig.11 This is a diagram showing a method for forming an aluminum oxide semiconductor layer by laser irradiation in the second embodiment.

[0033] Fig.12 This is a diagram showing the results of observing the changes in voltage and current obtained when laser irradiation is performed in Example 1 using an oscilloscope.

[0034] Fig.13 The diagram shows the results of SEM observation and EDS elemental analysis in Example 1.

[0035] Fig.14 This is a diagram showing the results of observing the changes in voltage and current obtained when laser irradiation is performed in Example 2 using an oscilloscope.

[0036] Fig.15 This is a diagram showing an image of the sample surface in Example 2 captured by an optical microscope.

[0037] Fig.16 The diagram shows the results of SEM observation and EDS elemental analysis in Example 2.

[0038] Fig.17 This is a diagram showing the results of EDS elemental analysis in Example 2.

[0039] Fig.18 It is a figure which shows Examples 1-2 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0040] [Implementation method 1]

[0041] Below, refer to Figures 1 to 8 , a semiconductor manufacturing method and a semiconductor manufacturing apparatus according to Embodiment 1 of the present invention are described. In addition, for the convenience of description, the same reference numerals are given to the same components and components having the same functions as those shown in each embodiment, and their descriptions are appropriately omitted.

[0042] [raw materials]

[0043] In the first embodiment, the substrate 1, which is a raw material for forming a semiconductor layer by a laser method, is made of aluminum oxide. The material of the substrate 1 may be a single crystal sapphire having a melting point of 2040°C, a non-crystalline (amorphous) or a polycrystalline material, in addition to the material commonly called aluminum oxide. The substrate 1 is in the form of a plate, but is not limited thereto, and may also be in the form of a rod, a wire, a powder, etc. In addition, the purity of the aluminum oxide used for the substrate 1 is as high as possible, but it may also be of a relatively low purity. For example, aluminum oxide having a purity of 99.4% or more or 4N sapphire may be used for the substrate 1.

[0044] [Semiconductor manufacturing equipment]

[0045] The semiconductor manufacturing apparatus 100 of the first embodiment is as follows Figure 1 As shown, it is composed of the following components relative to the substrate 1: a pressing plate 102 and an open pressing plate 103 with a through hole 103a, which serve as a clamp for contacting the anode 2 and the cathode 3 described later; a laser device 101; a light source for irradiating the substrate 1 with laser; a DC power supply 104 for controlling the voltage applied between the anode 2 and the cathode 3; a current limiting resistor 105 for limiting the current flowing between the anode 2 and the cathode 3; and a switch 106.

[0046] The anode 2 is disposed on one side of the substrate 1 ( Figure 1 In addition, the cathode 3 is arranged on the other side of the substrate 1 ( Figure 1 The pressing plate 102 and the perforated pressing plate 103 are plate-shaped fixtures for bringing the anode 2 and the cathode 3 into contact with the substrate 1, respectively.

[0047] [anode]

[0048] Aluminum is used, for example, in the anode 2. The shape of the anode 2 is a plate. In addition, the shape of the anode 2 may be, for example, powdered, and may be changed appropriately. The melting point of aluminum oxide is 2072°C. Therefore, if the substrate 1 melts, at least a portion of the aluminum (melting point 660°C) in contact with the substrate 1 melts. Therefore, the gap between the substrate 1 and the anode 2 is likely to disappear. As a result, the contact area between the two is increased, so that the anode polarization of the molten salt electrolysis in the substrate 1 can be reduced.

[0049] When an aluminum plate is used as the anode 2, a thin plate with a thickness of about 0.01 to 10 mm is preferably used to reduce the weight of the entire semiconductor manufacturing apparatus 100. However, in order to melt the entire anode 2 without destroying the structure, the thickness of the anode 2 is more preferably 1 mm or more.

[0050] The higher the purity of the aluminum plate used for the anode 2, the better. For example, an aluminum alloy containing other elements such as 1085 material (99.85% by mass, the remainder being Fe, Si, etc.) may be used.

[0051] In addition, the direction in which the laser is irradiated from the laser device 101 to the substrate 1 is not limited. When the laser is irradiated from the anode 2 toward the substrate 1, the laser is first irradiated to the anode 2, and after the anode 2 is destroyed or melted by the laser irradiation, the heat of the laser irradiation reaches the substrate 1. In this case, a small hole may be opened in advance in the anode 2 to directly irradiate the laser to the substrate 1.

[0052] [cathode]

[0053] In the cathode 3, for example, a platinum plate is used. In the cathode 3, oxygen (O 2 ) is reduced to oxygen ions (O 2- ) reaction. In addition, the cathode 3 can also use various materials, for example, the cathode 3 can use: platinum group metals such as rhodium, platinum group oxides such as iridium oxide, palladium oxide or ruthenium oxide, or platinum group compounds. In addition, the cathode 3 can also use: alloys containing the platinum group metals, platinum group oxides or platinum group compounds, or mixtures containing the platinum group metals, platinum group oxides or platinum group compounds. Furthermore, the cathode 3 can also use carbon.

[0054] Platinum (melting point 1768°C) is particularly excellent. The higher the purity of platinum, the better, but in the purpose of use of the cathode 3, if the platinum is commercially available with a purity (99.9%), it can fully function as the cathode 3. If the substrate 1 melts, there is a situation where a part of the platinum in contact with the substrate 1 melts. In this case, the gap between the substrate 1 and the cathode 3 is likely to disappear. As a result, the contact area between the substrate 1 and the cathode 3 is increased, so that the cathode polarization of the molten salt electrolysis in the substrate 1 can be reduced.

[0055] As with the anode 2 side, the direction in which the laser is irradiated from the laser device 101 to the substrate 1 is not limited. For example, when the laser is irradiated from the cathode 3 side toward the substrate 1, the laser is first irradiated to the cathode 3, and after the cathode 3 is destroyed or melted by the laser irradiation, the heat of the laser irradiation reaches the substrate 1. Usually, a small hole 3a is opened in advance in the cathode 3, and the laser is directly irradiated from the laser device 101 to the substrate 1 in a state where the surface of the substrate 1 is exposed.

[0056] The small holes 3a formed on the cathode 3 have the following advantages. That is, the substrate 1 is melted by laser irradiation, and a molten salt electrolysis reaction occurs. This reaction is the reduction of oxygen present on the surface of the cathode 3 to become O 2-Cathode reaction. It is believed that this cathode reaction occurs at the interface of the three phases of molten salt (alumina), cathode (platinum, solid or liquid) and oxidant (oxygen). Here, oxygen is required as a reactant at the contact point between cathode 3 and substrate 1. This oxygen can be oxygen in the air, or oxygen or oxygen mixed gas can be used. At this time, in order to smoothly carry out the molten salt electrolysis reaction, space for storing oxygen and the like in advance is required near cathode 3. Therefore, by using a cathode 3 with a small hole 3a, the space can be ensured.

[0057] Here, the melting point of platinum is 1768° C., which is lower than the melting point of aluminum oxide, 2072° C. Therefore, when the substrate 1 is melted by laser irradiation, it is considered that the portion of the cathode 3 in contact with the substrate 1 is melted even if the laser irradiation time is short. In addition, if the melting time of the cathode 3 is prolonged, there is a concern that the structure of the cathode 3 may be destroyed. Therefore, in order to prevent the structure of the cathode 3 from being destroyed, appropriate laser irradiation conditions must be set.

[0058] [Laser device]

[0059] The laser device 101 is a device for irradiating the substrate 1 with laser. The types of lasers irradiated by the laser device 101 include: disk laser (wavelength 1030nm), fiber laser (wavelength 1064nm), yttrium aluminum garnet (YAG) laser (wavelength 1064nm), excimer laser (wavelength varies depending on the type of gas in the laser medium), carbon dioxide laser (wavelength 1.6μm), semiconductor laser (wavelength varies depending on the constituent elements of the semiconductor, 375 to 2000nm, etc.). In the laser method of this embodiment, it is preferred to use any of the above lasers, and in order to perform an experiment to form an aluminum oxide semiconductor layer, it is more preferred to use a disk laser, a fiber laser, or a carbon dioxide laser.

[0060] [Method of irradiating sample with laser light]

[0061] Generally, the laser irradiation conditions of the laser device 101 can be finely adjusted. Specifically, the laser irradiation power (W), spot size (mmφ), irradiation time (ms), focus deviation (mm), etc. can be appropriately set. The wavelength of disk laser and fiber laser is about 1000nm, which is in the infrared region. Therefore, in principle, the laser should pass through the substrate 1 and cannot be processed.

[0062] However, in reality, there are irregularities or dirt on the surface of the substrate 1, so the heat of the laser is locally absorbed. By using the portion where the heat is absorbed as the starting point and transferring the heat from the starting point to the surroundings, it is possible to perform the target processing (melting of the substrate 1 in this embodiment). Here, in order to perform stable processing, it is preferable to pre-coat a very small amount of black lead powder on the surface of the substrate 1 to ensure that the heat absorption portion is reliably secured.

[0063] Usually, laser irradiation is performed multiple times on one substrate 1 using the laser device 101. The position where the laser irradiation is performed is usually planned in advance. The position where the laser irradiation is performed is aligned by fixing the substrate 1 and using a galvano scanner using a mirror, or fixing the laser device 101 and moving the substrate 1 on an XYZ stage, or both.

[0064] [Laser irradiation unit]

[0065] like Figure 1 As shown, the conductive pressing plate 102, the anode 2, the substrate 1, the cathode 3, and the conductive perforated pressing plate 103 are stacked in this order. This stacked structure is referred to as a "unit".

[0066] During laser irradiation, it is important to make the position of the small hole 3a of the cathode 3 coincide with the position of the through hole 103a of the perforated pressing plate 103. In addition, a clamp is used to apply a load to the pressing plate 102 and the perforated pressing plate 103, respectively, and the pressing plate 102 and the perforated pressing plate 103 are fixed. At this time, the pressing plate 102 and the clamp for applying a load to the pressing plate 102 must be insulated in advance by, for example, adding an insulating sheet. Similarly, the perforated pressing plate 103 and the clamp for applying a load to the perforated pressing plate 103 must be insulated in advance by, for example, adding an insulating sheet.

[0067] The DC power supply 104 is used to apply voltage to the unit. The DC power supply 104 is not only connected to the pressing plate 102 at the positive side, but also connected to the opening pressing plate 103 at the negative side. Figure 1 As shown, a current limiting resistor 105 and a switch 106 are arranged between the negative side of the DC power supply 104 and the hole pressing plate 103. The switch 106 can be turned on / off manually, but the timing of laser irradiation can also be synchronized with the on / off of the switch 106, or the switch 106 can be turned on before laser irradiation to automatically flow the current I when the molten salt electrolysis occurs by laser irradiation.

[0068] [Semiconductor manufacturing method]

[0069] Second, use Figures 1 to 9Next, a method for manufacturing a semiconductor layer using the semiconductor manufacturing apparatus 100 will be described. In addition, it is assumed that the semiconductor manufacturing apparatus 100 is operated in the ambient environment in the air at room temperature.

[0070] First, the anode 2 is arranged on the lower surface which is one main surface of the substrate 1, and the cathode 3 is arranged on the upper surface which is the other main surface of the substrate 1 facing the lower surface (arrangement step S1).

[0071] Next, while the anode 2 and the cathode 3 are in contact with the substrate 1, the substrate 1 is heated to a temperature above the melting point (2072°C) of the substrate 1 to be melted (heating step S2). Figure 5 As shown, this is performed by irradiating the substrate 1 with laser light from a laser device 101 .

[0072] The heating step S2 is described in detail below. In the heating step S2, the switch 106 is first turned on to apply a voltage between the anode 2 and the cathode 3. When the voltage is first applied between the anode 2 and the cathode 3, the current I does not flow through the substrate 1 which is an insulator.

[0073] The magnitude of the applied voltage varies depending on the constituent material of the cell or the laser irradiation conditions, and is set within a range of 1 to 60 V. In the present embodiment, in order to suppress the speed of molten salt electrolysis, a current limiting resistor 105 is arranged in series with the DC power supply 104 so that a current I exceeding a certain value does not flow. The amount of the current I flowing between the anode 2 and the cathode 3 is controlled.

[0074] Moreover, if Figure 5 As shown, laser light is emitted from the laser device 101 in a direction toward the perforated pressing plate 103. The laser light is irradiated from the laser device 101 onto the substrate 1 through the through hole 103a of the perforated pressing plate 103 and the small hole 3a of the cathode 3.

[0075] After the heating step S2, during the entire period when at least a portion of the substrate 1 is melted, as Figure 6 As shown, a current I flows between the anode 2 and the cathode 3 to perform molten salt electrolysis (molten salt electrolysis step S3). Molten salt electrolysis occurs at the interface between the substrate 1 and the anode 2 and at the interface between the substrate 1 and the cathode 3. In addition, the period during which the molten salt electrolysis step S3 is performed may also be a portion of the entire period during which at least a portion of the substrate 1 is melted.

[0076] In the molten salt electrolysis step S3, the substrate 1 is heated to a temperature above the melting point and melted. The heat is transferred from the substrate 1 to the anode 2 side and the cathode 3 side. The heat transferred from the substrate 1 to the anode 2 side melts a portion of the surface of the aluminum plate serving as the anode 2. The surface of the molten substrate 1 is in close contact with the surface of the molten anode 2. Anode reaction proceeds at this interface.

[0077] On the other hand, the heat transferred from the substrate 1 to the cathode 3 side also melts a portion of the surface of the platinum plate serving as the cathode 3. Here, the surface of the molten substrate 1 is in close contact with the surface of the molten cathode 3. By supplying oxygen in the atmosphere to the interface between the surface of the molten substrate 1 and the surface of the molten cathode 3, a cathode reaction proceeds at this interface.

[0078] After the molten salt electrolysis step S3, the substrate 1 is cooled to form the n-type semiconductor layer 12 and the p-type semiconductor layer 13 (semiconductor formation step S4). Specifically, in the semiconductor formation step S4, the laser irradiation by the laser device 101 is terminated. When the laser irradiation is terminated, the temperature of the substrate 1 decreases, and a part of the substrate 1 solidifies and changes into a solid. As a result, Figure 8 As shown, an n-type semiconductor layer 12 (n-type aluminum oxide semiconductor layer) in an oxygen-deficient or aluminum-excessive state is formed on the anode 2 side. Also, a p-type semiconductor layer 13 (p-type aluminum oxide semiconductor layer) in an oxygen-excess or aluminum-deficient state is formed on the cathode 3 side.

[0079] The thickness of the n-type semiconductor layer 12 and the p-type semiconductor layer 13 obtained by the semiconductor manufacturing method of the present embodiment can be changed according to the thickness of the substrate 1, the laser irradiation conditions, the amount of current I flowing between the anode 2 and the cathode 3 (current × time), etc. For example, when the thickness of the substrate 1 is set to 0.5 mm, the thickness of the n-type semiconductor layer 12 and the p-type semiconductor layer 13 can be formed in a wide range of 5 to 250 μm. In addition, by adjusting the electrolysis conditions during molten electrolysis, a pn junction in which the n-type semiconductor layer 12 and the p-type semiconductor layer 13 are in surface contact can be formed. However, the morphology of the liquid molten salt changes and increases as it flows. Therefore, the n-type semiconductor layer 12 and the p-type semiconductor layer 13 sometimes do not form neat layers. That is, there is also a case where a layer in which n-type semiconductor, p-type semiconductor, aluminum oxide and metal aluminum are mixed, or a layer in which any two or three of n-type semiconductor, p-type semiconductor, aluminum oxide and metal aluminum are mixed is formed.

[0080] Figure 2 to Figure 4 The diagram shows n-type semiconductor layer 12 and p-type semiconductor layer 13 formed by cooling to room temperature after molten salt electrolysis when the amount of current I flowing between anode 2 and cathode 3 is appropriately changed in Embodiment 1. Figure 2 to Figure 4 This shows a case where the morphological change due to the flow of the molten salt does not occur and the n-type semiconductor layer 12 and the p-type semiconductor layer 13 are formed in a regular layer shape. Figure 2In the case where the amount of current I is small, an n-type semiconductor layer 12 is formed on the anode 2 side. In addition, a p-type semiconductor layer 13 is formed on the cathode 3 side. In addition, an aluminum oxide layer 11 is present between the n-type semiconductor layer 12 and the p-type semiconductor layer 13. Since the aluminum oxide layer 11 is an insulator at room temperature, a semiconductor device is not realized.

[0081] Figure 3 Indicates the charge ratio of current I Figure 2 In the case where a pn junction is formed, an n-type semiconductor layer 12 is formed on the anode 2 side. In addition, a p-type semiconductor layer 13 is formed on the cathode 3 side. In addition, the n-type semiconductor layer 12 and the p-type semiconductor layer 13 are in contact at one interface to form a pn junction, thereby forming a pn diode. That is, Figure 3 Under the circumstances, a semiconductor device is realized.

[0082] In addition, Figure 3 In the figure, the reaction surface on the cathode 3 side is parallel to the reaction surface on the anode 2 side, and an ideal pn junction surface is drawn. However, in reality, the morphological changes caused by the flow of the molten salt occur, and the reaction surface on the cathode 3 side is not parallel to the reaction surface on the anode 2 side, or the cathode reaction rate and the anode reaction rate are uneven, and the ideal pn junction surface is not formed. As a result, the pn junction surface and the junction surface where pn junction cannot be formed and aluminum oxide is formed are mixed. In this case, even if the area of ​​the pn junction surface is small, the semiconductor device functions, but the device characteristics are uneven.

[0083] Figure 4 Indicates the charge ratio of current I Figure 3 The thickness of the p-type semiconductor layer 13 and the thickness of the n-type semiconductor layer 12 increase as the amount of current I increases. However, if the p-type semiconductor layer 13 and the n-type semiconductor layer 12 are mixed, a molten aluminum oxide layer 11 is formed. Molten aluminum oxide at high temperatures has ion conductivity due to ionization, but when the temperature drops to room temperature, it becomes insulating aluminum oxide, so it is different from the aluminum oxide layer 11. Figure 2 The structure is the same, and the semiconductor device is not realized.

[0084] In this embodiment, in order to obtain a pn junction diode, it is sufficient to form Figure 3 However, if it is not as shown Figure 3 Even if an ideal pn junction is not formed as in the example shown, it is difficult to manufacture a high-quality pn junction diode having stable characteristics due to the above-mentioned reasons.

[0085] The p-type semiconductor layer 13 and the n-type semiconductor layer 12 formed in this embodiment can be used as raw materials for an aluminum oxide semiconductor device and an aluminum oxide semiconductor cell.

[0086] Back to Fig. 9 , the manufacturing steps after the semiconductor forming step S4 are described. In the present embodiment, the separation step S5 is performed after the semiconductor forming step S4. In this separation step S5, first, the weight applied to the pressing plate 102 and the opening pressing plate 103 is removed, and only the n-type semiconductor layer 12 and the p-type semiconductor layer 13 sandwiched between the anode 2 and the cathode 3 are removed from the semiconductor manufacturing device 100. Next, the n-type semiconductor layer 12 and the p-type semiconductor layer 13 are cut off by, for example, cutting or sputtering. During sputtering, the p-type semiconductor layer 13 is shielded when the n-type semiconductor layer 12 is cut off, and the n-type semiconductor layer 12 is shielded when the p-type semiconductor layer 13 is cut off.

[0087] The n-type semiconductor layer 12 and the p-type semiconductor layer 13 are taken out, and the n-type semiconductor layer 12 can be used as the n-type aluminum oxide semiconductor raw material, and the p-type semiconductor layer 13 can be used as the p-type aluminum oxide semiconductor raw material. When at least two of the n-type semiconductor, the p-type semiconductor, the aluminum oxide, and the metallic aluminum are mixed in the formed substance along with the flow of the molten salt, the density (g / cm 3 ) are different from each other, and the mixed substances are aggregated. Specifically, after the formed substance is formed into a powder, the powder of each mixed substance is collected by centrifugal separation. As a result, the n-type semiconductor powder can be used for the n-type aluminum oxide semiconductor raw material, and the p-type semiconductor powder can be used for the p-type aluminum oxide semiconductor raw material.

[0088] By mixing an n-type aluminum oxide semiconductor raw material and a p-type aluminum oxide semiconductor raw material with an insulating aluminum oxide raw material, the carrier concentration of the mixed raw materials can be adjusted. Specifically, the adjustment step S6 is performed after the separation step S5. In this adjustment step S6, the n-type semiconductor layer 12 is sputtered simultaneously with the usual aluminum oxide to form a film. Alternatively, the n-type semiconductor powder collected by centrifugal separation is mixed with the usual aluminum oxide powder in an appropriate ratio to form an n-type aluminum oxide semiconductor whose carrier concentration is adjusted as a total amount. In either of the film formation by sputtering and the mixing by centrifugal separation, there is no problem even if a number of p-type semiconductors are included in the formed semiconductor layer. In addition, the p-type semiconductor layer 13 is sputtered simultaneously with the usual aluminum oxide to form a film. Alternatively, the p-type semiconductor powder collected by centrifugal separation is mixed with the usual aluminum oxide powder in an appropriate ratio to form a p-type aluminum oxide semiconductor whose carrier concentration is adjusted as a total amount. In the case of either the film formation by sputtering or the mixing by centrifugal separation, there is no problem even if a small amount of n-type semiconductor is contained in the formed semiconductor layer.

[0089] Figure 2 to Figure 4The p-type semiconductor layer 13 and the n-type semiconductor layer 12 shown in the figure are both raw materials for aluminum oxide semiconductor devices or semiconductor battery electrode materials. Figure 2 to Figure 4 The stacked structure composed of the p-type semiconductor layer 13 and the n-type semiconductor layer 12 shown in the figure can realize various semiconductor devices such as diodes, transistors and thyristors. Figure 2 to Figure 4 The p-type semiconductor layer 13 shown is used as a positive electrode material, and the n-type semiconductor layer 12 is used as a negative electrode material, so that a semiconductor secondary battery can be realized.

[0090] [Estimation of the formation process of the semiconductor layer]

[0091] Hereinafter, the mechanism of forming the n-type semiconductor layer 12 and the p-type semiconductor layer 13 will be described.

[0092] Figure 5 The figure shows the state where the substrate 1, which is an insulator, is melted by laser irradiation. The portion of the substrate 1 irradiated with laser light reaches a temperature higher than the melting point (2072°C in this case) and becomes a molten salt. As a result, if the switch 106 is closed, Figure 6 As shown, a current I caused by molten salt electrolysis flows.

[0093] When a current I is passed by molten salt electrolysis, an anode reaction represented by the following formula (1) occurs on the anode 2 side of the substrate 1. Also, a cathode reaction represented by the following formula (2) occurs on the cathode 3 side of the substrate 1.

[0094] Al→Al 3+ +3e……Formula (1)

[0095] O 2 +4e→2O 2- ……Formula (2)

[0096] 4Al+3O 2 →4Al 3+ +6O 2- ……Formula (3)

[0097] As described above, molten salt electrolysis occurs at a temperature above the melting point according to equations (1) and (2), as shown in equation (3), Al 3+ With O 2- The ions are accumulated in the substrate 1 , and form a molten ion layer serving as a basis for the n-type semiconductor layer 12 and a molten ion layer serving as a basis for the p-type semiconductor layer 13 .

[0098] When the laser irradiation is finished, the temperature drops. The temperature drop rate is not completely uniform in the molten ion layer forming the n-type semiconductor layer 12 and the molten ion layer forming the p-type semiconductor layer 13. Therefore, in each molten ion layer, solid and liquid coexist, and partially solidify to form Al 2 O 3 (a) by the remaining ionized portion of the molten state, or (b) by the solid Al 2 O 3 Although it is an insulator at room temperature, it has electronic conductivity at high temperatures close to its melting point. (c) Due to these two reasons, Figure 7 As shown, the anode reaction and the cathode reaction occur continuously. In the n-type semiconductor layer 12, O 2- Ion deficiency, Al 3+ There is an excess of ions, and the electrical balance collapses. In order to maintain electrical neutrality, a new donor energy level is formed in the n-type semiconductor layer 12. On the other hand, in the p-type semiconductor layer 13, Al 3+ Ion deficiency, O 2- The ions become excessive, and the electrical balance collapses. In order to maintain electrical neutrality, new acceptor levels are formed in the p-type semiconductor layer 13 .

[0099] It is further believed that if the temperature drops to room temperature, Figure 8 The n-type semiconductor layer 12 and the p-type semiconductor layer 13 are shown. That is, the n-type semiconductor layer 12 becomes an n-type semiconductor with oxygen deficiency or aluminum excess. On the other hand, the p-type semiconductor layer 13 becomes a p-type semiconductor with aluminum deficiency or oxygen excess. An insulating aluminum oxide layer 11 is formed in the region between these n-type semiconductor layer 12 and p-type semiconductor layer 13.

[0100] When the p-type semiconductor layer 13 and the n-type semiconductor layer 12 are in surface contact, a pn junction is formed, and a depletion layer is generated at the junction. The thickness of the depletion layer is determined by the carrier concentration of the newly generated donor level and the carrier concentration of the acceptor level. Based on the results of EDS analysis (Energy dispersive X-ray spectrometry) of the cross-section of the n-type semiconductor layer 12 and the p-type semiconductor layer 13, it is estimated that the maximum value of the carrier concentration is an extremely high concentration (10 21 ~10 23 Pieces / cm 3 ). Since the carrier concentration is extremely high, the thickness of the depletion layer is less than 1 nm, and tunnel current can flow easily. It is also believed that the electron state in the depletion layer is metallic, thereby obtaining high conductivity.

[0101] As described above, a semiconductor layer with a size of 20 μm or more can be formed. By aggregating the semiconductor layer to form a semiconductor layer with a size of 0.1 mm or more, a practical device material can be formed. In addition, by forming n-type semiconductor powder and p-type semiconductor powder and solidifying them separately, practical devices and semiconductor battery electrode materials of any size can be formed.

[0102] In addition, if Figure 1 and Figure 5 When the positive side and the negative side of the DC power supply 104 are switched, the anode 2 becomes the cathode and the cathode 3 becomes the anode. As a result, the opposite reaction to that in the first embodiment occurs, and a p-type semiconductor of aluminum oxide with excess oxygen is formed on the surface of the anode 2 by a cathode reaction, and an n-type semiconductor of aluminum oxide with deficient oxygen is formed on the surface of the cathode 3 by an anode reaction.

[0103] [Implementation method 2]

[0104] Secondly, refer to Figure 6 to Figure 11 , a semiconductor manufacturing method and a semiconductor manufacturing apparatus according to a second embodiment of the present invention are described. In addition, the state diagram of the substrate or semiconductor of the physical form 2 or the flowchart showing the processing procedure of the semiconductor manufacturing method is used again in the description of the first embodiment. Figure 6 to Figure 9 In addition, for the sake of convenience of description, components having the same functions as those described in the first embodiment are denoted by the same reference numerals, and description thereof may be omitted.

[0105] In the first embodiment, the substrate 1 is melted by laser irradiation and penetrates the substrate 1. In contrast, in the second embodiment, the substrate 1 is not penetrated by laser irradiation, but one main surface of the substrate 1 is melted into a flat shape by laser irradiation. This method is a method of generating molten salt electrolysis by passing a current between the anode 2 and the cathode 3 in contact with the melted one main surface.

[0106] [raw materials]

[0107] In Embodiment 2, as a substrate 1 of a raw material for forming a semiconductor layer by a laser method, aluminum oxide is used as in Embodiment 1. In addition, the material of the substrate 1 may be a single crystal sapphire having a melting point of 2040°C, a non-crystalline (amorphous) or a polycrystalline material, in addition to the material commonly called aluminum oxide. The substrate 1 is in the form of a plate, but is not limited thereto, and may also be in the form of a rod, a wire, a powder, etc. In addition, the purity of the aluminum oxide used for the substrate 1 is as high as possible, but it may also be of a relatively low purity. For example, aluminum oxide having a purity of 99.4% or more, or 4N sapphire may be used for the substrate 1.

[0108] [Semiconductor manufacturing equipment]

[0109] The semiconductor manufacturing apparatus 100 of the second embodiment has the following structure: Fig.10 As shown, a substrate 1 is arranged on an insulating pressing plate 112, and a plate-shaped anode 2 and a plate-shaped cathode 3 are separated and arranged thereon, and then an insulating pressing plate 113 is arranged on the anode 2, and an insulating pressing plate 114 is arranged on the cathode 3. In order to prepare for the situation where the substrate 1 is melted and penetrated by laser irradiation, a through hole 4 is opened in the central part of the pressing plate 112. Fig.10 Although not shown, the pressing plate 112, the pressing plate 113, the pressing plate 114, the anode 2 and the cathode 3 are fixed to each other so that the positional relationship does not shift. In addition, the semiconductor manufacturing apparatus 100 is composed of the following components: a laser device 101 for irradiating a laser to the substrate 1, a DC power supply 104 for applying a voltage between the anode 2 and the cathode 3, a current limiting resistor 105 and a switch 106.

[0110] The anode 2 is arranged on one end side of the upper surface of the substrate 1 ( Fig.10 In addition, the cathode 3 is arranged on the other end side of the substrate 1 ( Fig.10 The right side is in the middle). A jig for bringing the anode 2 into contact with the substrate 1 is mounted on the pressing plates 112 and 113. A jig for bringing the cathode 3 into contact with the substrate 1 is mounted on the pressing plates 112 and 114.

[0111] [anode]

[0112] An aluminum plate is used for the anode 2. In addition, the shape of the anode 2 is not limited to a plate shape, and may be, for example, a rod shape, or a shape obtained by solidifying powder into a plate shape or a rod shape. In the case of a plate shape, the thickness is preferably about 0.01 to 10 mm. In the case where the substrate 1 is melted by laser irradiation, it is considered that the portion of the anode 2 in contact with the substrate 1 is also melted. If the thickness of the anode 2 is large, the heat of the molten substrate 1 is easily dissipated to the outside through the anode 2. As a result, since the temperature rise of the contact surface of the anode 2 with the substrate 1 is suppressed, the anode 2 does not melt or is difficult to melt.

[0113] On the other hand, the thickness of the anode 2 is preferably 0.2 mm or less. If the melting time of the anode 2 is prolonged, the structure of the anode 2 is destroyed. It is necessary to set appropriate laser irradiation conditions.

[0114] The higher the purity of aluminum used for the anode 2 , the better. However, an aluminum alloy containing other elements such as 1085 material (99.85% by mass, the remainder being Fe, Si, etc.) may be used.

[0115] [cathode]

[0116] A platinum plate is used for the cathode 3. In addition, as the cathode 3, in addition to this, platinum group metals such as rhodium, platinum group oxides such as iridium oxide, palladium oxide or ruthenium oxide, or platinum group compounds can also be used. In addition, the cathode 3 can also use: an alloy containing the above-mentioned platinum group metals, platinum group oxides or platinum group compounds, or a mixture containing the above-mentioned platinum group metals, platinum group oxides or platinum group compounds. Furthermore, carbon can also be used for the cathode 3. In addition, the melting point of platinum is 1768°C. In addition, the higher the purity of platinum, the better. If it has a commercially available purity (99.9%), it can fully function as the cathode 3. The shape of the cathode 3 is not limited to a plate shape. In addition, it can also be a rod shape, or a shape in which powder is solidified into a plate shape or a rod shape. In the case of a plate shape, its thickness is preferably about 0.01 to 10 mm.

[0117] In addition, when platinum is used as the cathode 3, its melting point is lower than the melting point (2072° C.) of the substrate 1. Therefore, when the substrate 1 is melted by laser irradiation, it is considered that the portion of the cathode 3 in contact with the substrate 1 is also melted. If the melting time of the cathode 3 is prolonged, the structure of the cathode 3 is destroyed. Appropriate laser irradiation conditions must be set.

[0118] When the laser device 101 irradiates the substrate 1 with laser light, the laser light passes through between the pressing plates 113 and 114 and between the anode 2 and the cathode 3 in sequence, and irradiates the surface of the substrate 1. When viewed from the laser device 101 side, the portion of the surface of the substrate 1 irradiated with the laser light becomes the middle position between the front end 2b of the anode 2 and the front end 3b of the cathode 3.

[0119] [Laser device]

[0120] The laser device 101 is a device for irradiating the substrate 1 with laser. The types of lasers irradiated by the laser device 101 include: disk laser (wavelength 1030nm), fiber laser (wavelength 1064nm), YAG laser (wavelength 1064nm), excimer laser (wavelength varies depending on the type of gas in the laser medium), carbon dioxide laser (wavelength is 1.6μm), semiconductor laser (wavelength varies depending on the constituent elements of the semiconductor, 375 to 2000nm, etc.). In the laser method of this embodiment, it is preferred to use any of the above lasers. In order to perform the formation experiment of the aluminum oxide semiconductor layer in embodiment 2, it is more preferred to use a carbon dioxide laser.

[0121] [Method of irradiating sample with laser light]

[0122] Generally, the laser irradiation conditions can be finely adjusted by setting the laser device 101. For example, the irradiation energy (mJ), pulse width (ms), cycle (ms), irradiation time (s), focus deviation (mm), etc. can be appropriately set. The wavelength of a disk laser or a fiber laser is about 1000nm, which is located in the infrared region. Therefore, in principle, the laser should pass through the substrate 1 and cannot be processed.

[0123] However, in reality, if there are irregularities or dirt on the surface of the substrate 1, the heat of the laser is locally absorbed, and heat is transferred from this as a starting point to perform the target processing (melting of the substrate 1 in this embodiment). Here, in order to perform stable processing, it is preferable to ensure the starting point by applying a very small amount of black lead powder on the surface of the substrate 1 in advance. If it is a carbon dioxide laser, it will not penetrate the substrate 1 and easily melt into a flat shape, so there is no need to set a starting point.

[0124] Usually, laser irradiation is performed multiple times on one substrate 1 using the laser device 101. The position for laser irradiation is usually planned in advance. When aligning the position for laser irradiation, the substrate 1 is fixed and a current scanner using a mirror is used, or the laser device 101 is fixed and the substrate 1 is moved on an XYZ stage, or both of them may be used.

[0125] [Laser irradiation unit]

[0126] In implementation mode 2, if Fig.10 As shown, the pressing plate 112 and the substrate 1 are stacked in sequence, and further, the anode 2 and the pressing plate 113 are stacked in sequence on one end side of the substrate 1, and the cathode 3 and the pressing plate 114 are stacked in sequence on the other end side of the substrate 1 to form a unit.

[0127] The distance between the front end 2b of the anode 2 and the front end 3b of the cathode 3 is adjusted to 0.05 to 5mm. The reason is that if it is less than 0.05mm, the front end 2b of the anode 2 or the front end 3b of the cathode 3 is sometimes directly irradiated with laser, which is not preferred. In the case of more than 5mm, the heat generated on the substrate 1 by laser irradiation is not fully transmitted to the front end 2b of the anode 2 or the front end 3b of the cathode 3 through the substrate 1, so melting of the front end 2b of the anode 2 or the front end 3b of the cathode 3 does not occur. It is preferably adjusted to 0.15 to 0.5mm. From the laser device 101 side, it is important that the portion of the surface of the substrate 1 irradiated with the laser is the middle position between the front end 2b of the anode 2 and the front end 3b of the cathode 3.

[0128] A DC power supply 104 for applying voltage to the unit is connected to the anode 2 on the positive side and to the cathode 3 on the negative side via a current limiting resistor 105 and a switch 106. The switch 106 can be turned on / off manually, or the timing of laser irradiation can be synchronized with the on / off of the switch 106, or the switch 106 can be turned on before laser irradiation to automatically flow the current I when molten salt electrolysis is generated by laser irradiation.

[0129] [Semiconductor manufacturing method]

[0130] Second, use Fig. 9 , Fig.10 and Fig.11 Next, a method for manufacturing a semiconductor layer using the semiconductor manufacturing apparatus 100 will be described. In addition, the environment around the semiconductor manufacturing apparatus 100 is set to an environment in which operations are performed in the air at room temperature.

[0131] First, the anode 2 and the cathode 3 are arranged on one main surface of the substrate 1 (arrangement step S1 ).

[0132] Next, while the anode 2 and the cathode 3 are in contact with the substrate 1, the substrate 1 is heated to a temperature above the melting point (2072°C) of the substrate 1 to be melted (heating step S2). Fig.11 As shown, the substrate 1 is irradiated with laser light from a laser device 101 .

[0133] The heating step S2 is described in detail below. In the heating step S2, first, the switch 106 is turned on to apply a voltage between the anode 2 and the cathode 3. When the voltage is initially applied between the anode 2 and the cathode 3, no current I flows through the substrate 1 which is an insulator.

[0134] The magnitude of the applied voltage varies depending on the constituent material of the cell or the laser irradiation conditions, but is set within a range of 1 to 60 V. In the present embodiment, in order to suppress the speed of molten salt electrolysis, a current limiting resistor 105 is arranged in series with the DC power supply 104 so that a current I exceeding a certain value does not flow. The amount of the current I flowing between the anode 2 and the cathode 3 is controlled.

[0135] Then, if Fig.11 As shown, laser light is emitted from laser device 101 toward substrate 1. Laser light is irradiated from laser device 101 onto the surface of substrate 1 located at an intermediate position between the front end 2b of anode 2 and the front end 3b of cathode 3.

[0136] After the heating step S2, during the entire period when at least a portion of the substrate 1 is melted, as Figure 6As shown, a current I flows between the anode 2 and the cathode 3 to perform molten salt electrolysis (molten salt electrolysis step S3). In addition, the period for performing the molten salt electrolysis step S3 may be only a part of the entire period during which at least a part of the substrate 1 is melted.

[0137] In the molten salt electrolysis step S3, the substrate 1 is heated to a temperature above the melting point and melted. The heat is transferred from the substrate 1 to the front end 2b of the anode 2 and the front end 3b of the cathode 3. The heat transferred from the substrate 1 to the front end 2b of the anode 2 melts a portion of the surface of the front end 2b of the anode 2. The surface of the molten substrate 1 is in close contact with the surface of the front end 2b of the molten anode 2. The anode reaction is carried out at this interface.

[0138] On the other hand, the heat transmitted from the substrate 1 to the front end 3b of the cathode 3 melts a portion of the surface of the front end 3b of the cathode 3. The surface of the molten substrate 1 is in close contact with the surface of the front end 3b of the molten cathode 3. Oxygen in the atmosphere is supplied to the interface between the surface of the molten substrate 1 and the surface of the front end 3b of the molten cathode 3, and a cathode reaction proceeds at this interface.

[0139] Through the anode reaction and cathode reaction, a product 5 is formed in the substrate 1. The end 5a of the product 5 close to the anode 2 becomes a state of oxygen ion deficiency or aluminum ion excess. In addition, the end 5b of the product 5 close to the cathode 3 becomes a state of oxygen ion excess or aluminum ion deficiency. After the molten salt electrolysis step S3, the product 5 is cooled to form an n-type semiconductor layer 12 and a p-type semiconductor layer 13 (semiconductor formation step S4). Specifically, in the semiconductor formation step S4, the laser irradiation using the laser device 101 is ended. If the laser irradiation is ended, the temperature of the product 5 drops. A portion of the product 5 solidifies and changes into a solid. As a result, Figure 8 As shown, an n-type semiconductor layer 12 in an oxygen-deficient or aluminum-excessive state is formed on the anode 2 side. Also, a p-type semiconductor layer 13 in an oxygen-excessive or aluminum-deficient state is formed on the cathode 3 side.

[0140] The thickness of the n-type semiconductor layer 12 and the p-type semiconductor layer 13 obtained by the semiconductor manufacturing method of the second embodiment can be changed according to the thickness of the substrate 1, the laser irradiation conditions, the amount of current I flowing between the anode 2 and the cathode 3 (current × time), etc. For example, the thickness of the n-type semiconductor layer 12 and the p-type semiconductor layer 13 can be formed in a wide range of 1 to 100 μm. In addition, by adjusting the electrolysis conditions during melt electrolysis, a pn junction in which the n-type semiconductor layer 12 and the p-type semiconductor layer 13 are in surface contact can be formed.

[0141] In addition, if Fig.10 and Fig.11When the positive and negative sides of the DC power supply 104 are switched, the anode 2 becomes the cathode and the cathode 3 becomes the anode. As a result, a reaction opposite to that in the first embodiment occurs, and a p-type semiconductor of oxygen-excess aluminum oxide is formed on the surface of the anode 2, and an n-type semiconductor of oxygen-deficient aluminum oxide is formed on the surface of the cathode 3.

[0142] Back to Fig. 9 , the manufacturing steps after the semiconductor forming step S4 are described. In the second embodiment, the separation step S5 is also performed after the semiconductor forming step S4. In this separation step S5, first, the pressing plate 113, the pressing plate 114, the anode 2 and the cathode 3 are removed, and the substrate 1 formed with the n-type semiconductor layer 12 and the p-type semiconductor layer 13 is removed from the semiconductor manufacturing device 100. Next, the n-type semiconductor layer 12 and the p-type semiconductor layer 13 are separated by, for example, cutting or sputtering. In the case of sputtering, the p-type semiconductor layer 13 is shielded when the n-type semiconductor layer 12 is separated, and the n-type semiconductor layer 12 is shielded when the p-type semiconductor layer 13 is separated. In addition, the respective densities (g / cm 3 ) are different from each other, so it is also possible to collect a large amount of product 5 to form a powder, and then collect the powder of each monomer by centrifugal separation.

[0143] The n-type semiconductor and p-type semiconductor separated are taken out, and the n-type semiconductor can be used for the n-type aluminum oxide semiconductor raw material, and the p-type semiconductor can be used for the p-type aluminum oxide semiconductor raw material. The carrier concentration can be adjusted by mixing these aluminum oxide semiconductor raw materials with insulating aluminum oxide raw materials.

[0144] Specifically, the adjustment step S6 is performed after the separation step S5. In this adjustment step S6, the n-type aluminum oxide semiconductor layer with adjusted carrier concentration is formed by sputtering the n-type semiconductor layer 12 and the usual aluminum oxide at the same time. Alternatively, the n-type semiconductor powder collected by centrifugal separation is mixed with the usual aluminum oxide powder in an appropriate ratio to form an n-type aluminum oxide semiconductor with adjusted carrier concentration as the total amount. In the case of either the film formation by sputtering or the mixing by centrifugal separation, there is no problem even if the formed semiconductor layer contains some p-type semiconductors. In addition, the p-type semiconductor layer 13 is sputtered together with the usual aluminum oxide to form a film. Alternatively, the p-type semiconductor powder collected by centrifugal separation is mixed with the usual aluminum oxide powder in an appropriate ratio to form a p-type aluminum oxide semiconductor with adjusted carrier concentration as the total amount. In the case of either the film formation by sputtering or the mixing by centrifugal separation, there is no problem even if the formed semiconductor layer contains some n-type semiconductors.

[0145] Both the p-type semiconductor layer 13 and the n-type semiconductor layer 12 serve as raw materials for aluminum oxide semiconductor devices and semiconductor battery electrode materials. In addition, if a laminated structure is formed by combining the p-type semiconductor layer 13 and the n-type semiconductor layer 12, various semiconductor devices and semiconductor batteries such as diodes, transistors, and thyristors can be realized. In addition, in the case of n-type semiconductor powder and p-type semiconductor powder, by solidifying these powders, practical devices of any size and semiconductor battery electrode materials can be formed.

[0146] [Examples and Comparative Examples]

[0147] Below, also refer to Fig.18 Examples and comparative examples will be described.

[0148] [Example 1]

[0149] Below, refer to Figures 1 to 9 and Fig.18 , Example 1 is described. In Example 1, the substrate 1 is an aluminum plate (alumina plate) with a size of 50×50×0.5 mm and 99.6%. The anode 2 is a 5N aluminum plate with a size of 50×50×0.5 mm. The cathode 3 is a 4N platinum plate with a size of 50×50×0.1 mm, and the 4N platinum plate has 9 small holes 3a with a diameter of 1 mm in the center for passing the laser.

[0150] The pressing plate 102 on the anode 2 side is a SUS304 plate of 80×80×10 mm in size. The perforated pressing plate 103 on the cathode 3 side is a SUS304 plate of 80×80×10 mm in size, and the SUS304 plate has 9 through holes 103a of 1 mm in diameter in the center for passing laser light.

[0151] like Figure 1 As shown, the pressing plate 102, the anode 2, the substrate 1, the cathode 3, and the perforated pressing plate 103 are sequentially stacked to form a unit.

[0152] At this time, the overlapping accuracy of the 9 small holes 3a of the cathode 3 and the 9 through holes 103a of the perforated pressing plate 103 is set to within 0.1 mm so that the laser can be irradiated to the substrate 1. In addition, the pressing plate 102 and the perforated pressing plate 103 are fixed by applying a weight to each of them using, for example, a clamp.

[0153] At this time, an insulating sheet made of Teflon (registered trademark) with a thickness of 1 mm is added to the entire clamping portion of the jig to electrically insulate the pressing plate 102 and the perforated pressing plate 103. In addition, the material of the insulating sheet can be changed appropriately.

[0154] TruDisk10003 (disk laser manufactured by TRUMPF) was used as the laser device 101. PMX500-0.1A (manufactured by KIKUSUI ELECTRONICS CO., LTD.) was used as the DC power supply 104. DS-5412A (manufactured by Iwasaki Tsushinki Co., Ltd.) was used as the oscilloscope for measuring the changes in voltage and current.

[0155] First, in the first through hole 103a in 9, Figure 1 With the switch 106 closed, the laser irradiation power was 500 W, the spot size φ was 0.3 mm, the irradiation time was 500 ms, and the focus deviation was ±0 mm. It was confirmed in advance that alumina could be melted well under this laser irradiation condition.

[0156] Next, at the second through hole 103a in position 9, the DC power supply 104 is set to a constant voltage mode of 60V, such as Figure 5 As shown, after the switch 106 is turned on, laser irradiation is immediately performed under the same conditions as described above. At this time, the current limiting resistor 105 is set to 10Ω. After confirming that the current I flows during the laser irradiation time, the switch 106 is turned off. Thus, a product with a diameter of about 1.2 mm is obtained.

[0157] exist Fig.12 , the result of observing the changes in voltage and current obtained when laser irradiation is performed using an oscilloscope. The right side of the horizontal axis relative to 0.0 seconds represents the time after the start of laser irradiation, and the left side relative to 0.0 seconds represents the time before the start of laser irradiation. The left vertical axis represents voltage, and the right vertical axis represents current.

[0158] like Fig.12 As shown, before laser irradiation (left side of 0.0 second), the voltage is about 60V, but it drops sharply immediately after laser irradiation. Then, it is 0-8V until 0.5 second, but after 0.5 second, the voltage rises slightly, but after 2.2 seconds, it becomes about 0V.

[0159] On the other hand, the current peaked immediately after laser irradiation and reached 0.1 A immediately. Then, it maintained 0.1 A until 2.2 seconds. After 2.2 seconds, it dropped sharply to 0.0 A.

[0160] Based on the above, it is considered that the period from 0.0 seconds to 1.0 seconds occurs Figure 6 The anode reaction and cathode reaction shown are formed during the period from 1.0 second to 2.2 seconds. Figure 7 The p-type semiconductor layer 13 and the n-type semiconductor layer 12 are shown.

[0161] The unit is disassembled and the substrate 1 is taken out, and a scanning electron microscope (SEM) observation and EDS elemental analysis are performed on the sample formed when the second through hole 103a among the 9 locations is irradiated with a laser and a current I is passed. First, since a portion of aluminum is attached on the opposite side of the laser device 101 (the anode 2 side), it is completely removed. Next, the formed sample is taken out, and the substrate 1 is divided into two parts by hand in such a way that the cross section is roughly divided into two equal parts by the through hole 103a. The cross section of the single-side sample and the results of SEM observation and EDS elemental analysis of the cross section from the anode 2 direction are shown in FIG. Fig.13 . Fig.13 In the three figures on the upper side (first row), image 1301 is a SEM image, image 1302 is an element mapping image of Al in the same location as image 1301, and image 1303 is an element mapping image of O in the same location as image 1301.

[0162] Fig.13 In the three figures below (the second row), image 1304 is a SEM image, image 1305 is an elemental mapping image of Al in the same place as image 1304, and image 1306 is an elemental mapping image of O in the same place as image 1304. However, image 1304 in the second row was observed at a different time from the elemental mapping image, and CT (carbon tape, the adhesive of carbon tape) in all other images was not captured.

[0163] exist Fig.13 In the figure, the "B" part represents the bulk. Regarding the "a" part, although Al is strongly detected, the part where O is basically not detected can be judged as aluminum metal. Regarding the "v" part, although Al is the same as the bulk, the detection of O is less than the bulk, which can be judged as an oxygen-deficient n-type semiconductor. Regarding the "e" part, although Al is the same as the bulk, the detection of O is greater than the bulk, which can be judged as an oxygen-excess p-type semiconductor. In addition, the "CT" part represents the places where the adhesives of the carbon tape exist respectively as described above.

[0164] Based on the above, it is clear that the present method can form p-type semiconductors and n-type semiconductors. However, the positions of the n-type semiconductors in the "v" part and the p-type semiconductors in the "e" part are not regular. Figure 2 to Figure 4 The neat layers shown in the figure are inferred to be caused by the excessive energy of laser irradiation under these conditions. In order to form neat layered semiconductors, the structures of the anode and cathode, the laser irradiation conditions, the amount of current, etc. must be optimized. In addition, the n-type semiconductor is oxygen-deficient aluminum oxide, and the p-type semiconductor is oxygen-excess aluminum oxide, but it was confirmed by electron beam diffraction that these are all amorphous or amorphous containing some polycrystals.

[0165] [Example 2]

[0166] Secondly, refer to Figures 10 to 18 , Example 2 is described. In Example 2, the substrate 1 is an aluminum plate (alumina plate) with a size of 25×25×0.5 mm and 99.6%. The anode 2 is an aluminum plate with a size of 20×40×0.18 mm and 1085 material (99.85% by mass, the rest is Fe, Si, etc.). In addition, the cathode 3 is a 4N platinum strip plate with a size of 1.5×30×0.2 mm.

[0167] like Fig.10 As shown, a substrate 1 is arranged on a pressing plate 112, and one end portion ( Fig.10 On the left side of the substrate 1, the anode 2 and the pressing plate 113 are stacked in sequence. Fig.10 The cathode 3 and the pressing plate 114 are sequentially overlapped (on the right side of the anode 2). At this time, the front end 2b of the anode 2 and the front end 3b of the cathode 3 are parallel, and the interval between them is set to 0.20mm. In addition, the laser passes through the middle between the front end 2b and the front end 3b and irradiates the substrate 1.

[0168] The substrate 1 and the anode 2 are held between the pressing plates 112 and 113, and the substrate 1 and the cathode 3 are held between the pressing plates 112 and 114. At this time, the anode 2 and the cathode 3 are not in electrical contact.

[0169] The laser device 101 was a carbon dioxide laser SPL2305-E400 manufactured by Shibuya Industry Co., Ltd. The DC power supply 104 was PMX500-0.1A manufactured by Kikusui Electronics Co., Ltd. The oscilloscope used to measure the changes in voltage and current was DS-5412A (manufactured by Iwasaki Communication Equipment Co., Ltd.).

[0170] First, without installing the anode 2 and the cathode 3 on the substrate 1, the laser was irradiated to the substrate 1 to determine whether the melting morphology of the substrate 1 reached a good laser irradiation condition. As a result, under the irradiation conditions of irradiation pulse energy of 100mJ, pulse width of 0.1ms, cycle of 10ms, irradiation time of 0.5s, and focus deviation of 4.0mm, a melting mark with a diameter of about 0.7m was obtained on the surface of the substrate 1, confirming that the aluminum oxide could be melted well.

[0171] Secondly, if Fig.11As shown, an anode 2 and a cathode 3 are installed on a substrate 1, a DC power supply 104 is set to a constant voltage mode of 60V, and after turning on a switch 106, laser irradiation is immediately performed under the same conditions as described above. The current limiting resistor 105 is set to 0Ω. After confirming that the current I flows during the laser irradiation time, the switch 106 is turned off.

[0172] The oscilloscope observation results of the voltage and current at this time are shown in Fig.14 The right side of the horizontal axis relative to 0.0 seconds represents the time after the start of laser irradiation, and the left side relative to 0.0 seconds represents the time before the start of laser irradiation. The left vertical axis represents voltage. The right vertical axis represents current. In addition, Fig.14 In the measurement shown, the trigger level of the oscilloscope was set to a voltage of 58 V or less, so the trigger was performed 0.2 seconds after the laser irradiation. Therefore, the actual elapsed time from the laser irradiation is the time obtained by adding 0.2 seconds to the reading on the time axis.

[0173] like Fig.14 As shown, before laser irradiation (left side relative to 0.0 second), the voltage was maintained at about 60V, but it was slightly lowered by laser irradiation, and the unstable state was maintained for about 2 seconds. Then, it was restored to 60V.

[0174] On the other hand, the current is basically impossible to measure. As mentioned above, in the oscilloscope, the current is buried in the noise and cannot be detected. In the direct reading of the ammeter, a current of about 4 mA is measured from 0.0 seconds to 2.0 seconds, and a current of 0 mA is measured after 2 seconds. In this experiment, it is expected that a current of about 0.1 A will flow, but in fact it is about 4 mA, and the formation of semiconductors is also small.

[0175] The reason why the current is less than expected is considered to be as follows. That is, the anode 2 and the cathode 3 are large relative to the size of the molten portion of the substrate 1, and the heat capacity is also large, so the heat of the molten portion of the substrate 1 brought by laser irradiation is transmitted to the anode 2 and the cathode 3 through the front end 2b of the anode 2 and the front end 3b of the cathode 3, and it is easy to dissipate heat. Therefore, it is believed that the reason is that the temperature rises to the extent that molten salt electrolysis occurs at the front end 2b and the front end 3b is small, or the time for temperature rise is very short.

[0176] exist Fig.15, which is an image obtained by photographing the formed sample surface using an optical microscope. The blackened portion located in the center of the substrate 1 is the melted portion formed by laser irradiation. The portion surrounded by the dotted line on the left is the position of the cathode 3 plate, and the portion surrounded by the dotted line on the right is the position of the anode 2 plate. The position of the front end 3b of the cathode 3 and the position of the front end 2b of the anode 2 are shown. The interval between the front end 3b and the front end 2b is 0.2mm. The size of the melted portion is about 0.7mm above and below the figure. This is roughly the same as the case where the anode 2 and cathode 3 are not installed and the laser irradiation is performed.

[0177] In contrast, the width of the formed sample is about 0.3 mm. On the cathode 3 side (left side), the line on the molten portion side is substantially consistent with the line on the front end 3b, but on the anode 2 side (right side), the line on the right side of the molten portion extends to the right side by about 0.1 mm compared to the front end 2b.

[0178] Fig.16 is with Fig.15 Results of SEM observation and EDS element analysis of the same sample. Image 1601 is a SEM image, image 1602 is an element mapping image of Al, and image 1603 is an element mapping image of O.

[0179] according to Fig.16 , it is difficult to understand the difference in strength between Al and O, so only Fig.16 The image 1602 and the image 1603 are enlarged and shown in Fig.17 Image 1701 is an enlarged view of image 1602 , and image 1702 is an enlarged view of image 1603 .

[0180] like Fig.17 As shown, the dotted circle is marked at the same position in the image 1701 and the image 1702. If the three circles represented by "e" are compared, it can be seen that the intensity of O is slightly higher than that of Al, forming a p-type semiconductor with excess oxygen. Fig.15 and Fig.16 , a p-type semiconductor is formed along the front end 3b of the cathode 3.

[0181] On the other hand, if the three circles indicated by "v" are compared, it can be seen that the intensity of O is slightly lower than that of Al, forming an oxygen-deficient n-type semiconductor. Fig.15 and Fig.16 , an n-type semiconductor is formed between the substrate 1 and the vicinity of the front end 2b of the anode 2.

[0182] Compared with Example 1, the amount of product in Example 2 is very small. The reason is that the amount of electricity during laser irradiation is 0.1A×2.2s in Example 1, while it is 4mA×2s in Example 2, which is 1 / 27. By making the anode 2 and the cathode 3 in the form of wires instead of plates to reduce the size, etc., the amount of heat generated during laser irradiation can be reduced, and the amount of electricity in Example 2 can be increased to increase the yield of semiconductors.

[0183] In addition, the n-type semiconductor is oxygen-deficient alumina, and the p-type semiconductor is oxygen-excess alumina, but electron beam diffraction confirmed that these are amorphous or amorphous containing a small amount of crystals. Therefore, it is more accurate to say that the n-type semiconductor is "oxygen-deficient amorphous alumina" and the p-type semiconductor is "oxygen-excess amorphous alumina".

[0184] [Comparative Example 1]

[0185] Hereinafter, a description will be given of Comparative Example 1 which was conducted to analyze the results of Examples 1 and 2. Comparative Example 1 differs from Examples 1 and 2 in that the molten salt electrolysis step S3 is not conducted.

[0186] The size of the product was about the same as that of Example 1, with a diameter of 1.2 mm. The formed material was subjected to EDS elemental analysis. On the opposite side of the laser device 101 (the anode 2 side), since a portion of aluminum metal was attached, it was completely removed, and the portion considered to be the surface of the substrate 1 was subjected to EDS analysis.

[0187] As a result, Al and O were detected as elements. For reference, Al and O were also measured for a portion of the substrate 1 that was not irradiated with laser light by the laser device 101 , and there was no difference in the intensity of Al and O. That is, in Comparative Example 1, a semiconductor layer could not be formed.

[0188] [Comparative Example 2]

[0189] Next, a description will be given of Comparative Example 2. Comparative Example 2 is different from Examples 1 and 2 in that laser irradiation is not performed using the laser device 101 .

[0190] In Comparative Example 2, a 5N aluminum plate with a size of 24×24 mm and a thickness of 0.1 mm was used as the substrate 1. A 5N aluminum Al (φ76×6 mm thick) manufactured by Furuuchi Chemical was used as a target. 2 The sputtering was performed for about 40 minutes under the condition of a total pressure of 0.4 Pa, thereby providing an aluminum oxide film of about 30 nm on the aluminum plate. The sputtering apparatus used was SPC-350 manufactured by NEC Anelva.

[0191] Next, a product was formed by sparking using a probe (manufactured by Budgetsensors) in a scanning probe microscope JSPM-5200 manufactured by JEOL Ltd. The aluminum plate side was used as the anode 2, the probe side was used as the cathode 3, and the applied voltage was set to 60 V, and the voltage was applied at a scanning speed of about 10 V / s. Sparking was performed at an applied voltage of about 20 V. Thus, in Comparative Example 2, a very small product with a diameter of about 1 μm was formed.

[0192] A cross-section sample of the product was prepared using FIB (Focused Ion Beam), and TEM observation and EDS elemental analysis were performed. As a result, Al and O were detected as elements. Since there was more O and less Al on the surface side (cathode side) of the product, it was considered that a p-type semiconductor layer was formed. In addition, since there was less O and more Al on the aluminum side (anode side) of the product, it was considered that an n-type semiconductor layer was formed.

[0193] An aluminum oxide layer 11 as an insulator is present between the p-type semiconductor layer 13 and the n-type semiconductor layer 12, but a portion where the p-type semiconductor layer 13 and the n-type semiconductor layer 12 are in direct contact is considered to be a pn junction. The n-type semiconductor is oxygen-deficient amorphous aluminum oxide, and the p-type semiconductor is oxygen-excess amorphous aluminum oxide.

[0194] The results of Example 1, Example 2, Comparative Example 1 and Comparative Example 2 described above are summarized in Fig.18 In Examples 1 and 2, the target p-type semiconductor layer 13 and n-type semiconductor layer 12 can be obtained by irradiating the substrate 1 with laser light and performing molten salt electrolysis by passing electricity.

[0195] In contrast, when laser irradiation was performed using the laser device 101 but molten salt electrolysis was not performed as in Comparative Example 1, no semiconductor layer was obtained. Also, as in Comparative Example 2, although the product obtained by ignition was semiconductorized, its size was small at about 1 μm, and a large semiconductor layer could not be obtained.

[0196] 〔Summarize〕

[0197] A semiconductor manufacturing method in one embodiment of the present invention includes: a configuration step S1, configuring an anode 2 for undergoing an oxidation reaction at one end of a substrate 1 comprising aluminum oxide, and configuring a cathode 3 for undergoing a reduction reaction at the other end; a heating step S2, heating the substrate 1 to melt it in a state where the anode 2 is in contact with one end of the substrate 1 and the cathode 3 is in contact with the other end of the substrate 1; a molten salt electrolysis step S3, performing molten salt electrolysis by passing a current I between the anode 2 and the cathode 3 during the entire period or a part of the period when at least a part of the substrate 1 is melted; and a semiconductor formation step S4, cooling the substrate 1 after the molten salt electrolysis step S3 to form a p-type semiconductor layer 13 and an n-type semiconductor layer 12.

[0198] In addition, laser light is used for heating the substrate 1 in the heating step S2 , and the laser light includes at least one of a YAG laser, a disk laser, a fiber laser, an excimer laser, a carbon dioxide laser, and a semiconductor laser.

[0199] According to the above configuration, the substrate 1 can be heated efficiently.

[0200] In addition, the anode 2 contains aluminum, and the cathode 3 contains platinum.

[0201] In addition, the anode 2 contains platinum, and the cathode contains aluminum.

[0202] In addition, the base material 1 is formed of a powdery or plate-like material.

[0203] In addition, it includes: a separation step S5 of separating only the p-type semiconductor layer 13 and the n-type semiconductor layer 12 formed in the semiconductor forming step S4; and an adjustment step S6 of forming an aluminum oxide semiconductor layer with adjusted carrier concentration by sputtering the p-type semiconductor layer 13 and / or the n-type semiconductor layer 12 separated in the separation step S5 simultaneously with normal aluminum oxide.

[0204] The semiconductor manufacturing device 100 used in the semiconductor manufacturing method comprises: a pressing plate 102 and an open pressing plate 103, which are used to make the anode 2 where an oxidation reaction occurs contact with one end of the substrate 1, and to make the cathode 3 where a reduction reaction occurs contact with the other end of the substrate 1; a DC power supply 104, which is used to apply a voltage between the anode 2 and the cathode 3; and a laser device 101, which serves as a light source for irradiating the substrate 1 with laser.

[0205] In addition, the present invention is not limited to the above-described embodiments and examples, and various changes can be made within the scope of the technical scheme. Embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0206] Description of Reference Numerals

[0207] 1: Base material

[0208] 2: Anode

[0209] 2a: Small hole

[0210] 2b: Frontend

[0211] 3: Cathode

[0212] 3a: Small hole

[0213] 3b: Frontend

[0214] 4: Through hole

[0215] 5: Spawn

[0216] 5a: End

[0217] 5b: End

[0218] 11: Aluminum oxide layer

[0219] 12: n-type semiconductor layer (n-type aluminum oxide semiconductor layer)

[0220] 13: p-type semiconductor layer (p-type aluminum oxide semiconductor layer)

[0221] 100: Semiconductor manufacturing equipment

[0222] 101: Laser device (light source)

[0223] 102: Press plate

[0224] 103: Opening press plate

[0225] 103a: Through hole

[0226] 104: DC power supply

[0227] 105: Current limiting resistor

[0228] 106: Switch

[0229] 112: Press plate

[0230] 113: Press plate

[0231] 114: Press plate

[0232] S1: Configuration steps

[0233] S2: Heating step

[0234] S3: Molten Salt Electrolysis Step

[0235] S4: Semiconductor formation step

[0236] S5: Separation step

[0237] S6: Adjustment steps

Claims

1. A semiconductor manufacturing method, characterized in that: Include: a configuration step of configuring an anode for an oxidation reaction at one end of a substrate comprising aluminum oxide, and configuring a cathode for a reduction reaction at the other end of the substrate; a heating step of heating the substrate to melt the substrate in a state where the anode is in contact with one end of the substrate and the cathode is in contact with the other end of the substrate; a molten salt electrolysis step of performing molten salt electrolysis by passing a current between the anode and the cathode during the entire period or a part of the period during which at least a part of the substrate is melted; as well as The semiconductor forming step is to cool the substrate after the molten salt electrolysis step to form a p-type aluminum oxide semiconductor layer and / or an n-type aluminum oxide semiconductor layer.

2. The semiconductor manufacturing method according to claim 1, characterized in that: In the heating step, laser light is used when heating the substrate, and The laser includes at least one of yttrium aluminum garnet laser, disk laser, fiber laser, excimer laser, carbon dioxide laser and semiconductor laser.

3. The semiconductor manufacturing method according to claim 1 or 2, characterized in that: The anode comprises aluminum or an aluminum alloy, and The cathode includes platinum or a metal at least a portion of the surface of which is coated with platinum.

4. The semiconductor manufacturing method according to claim 1 or 2, characterized in that: The anode comprises platinum or a metal at least a portion of which is coated with platinum, and The cathode includes aluminum or an aluminum alloy.

5. The semiconductor manufacturing method according to claim 1 or 2, characterized in that: The substrate includes a powdery or plate-like material.

6. The semiconductor manufacturing method according to claim 1 or 2, characterized in that: Include: a separation step of separating only the p-type aluminum oxide semiconductor layer and / or the n-type aluminum oxide semiconductor layer formed in the semiconductor forming step; as well as The adjustment step is to form an aluminum oxide semiconductor layer having an adjusted carrier concentration by simultaneously sputtering the p-type aluminum oxide semiconductor layer and / or the n-type aluminum oxide semiconductor layer separated in the separation step and aluminum oxide.

7. A semiconductor manufacturing device, used in the semiconductor manufacturing method according to claim 1 or 2, characterized in that: have: A fixture for making an anode where an oxidation reaction occurs contact with one end of the substrate, and making a cathode where a reduction reaction occurs contact with the other end of the substrate; A DC power supply, used to apply a voltage between the anode and the cathode; as well as A light source irradiates the substrate with laser light.

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