JP2013065496A - Method for manufacturing silicon secondary battery amorphous electrode by high-frequency atmospheric pressure plasma cvd - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-speed and low-cost method for forming a film of amorphous (non-crystal) silicon carbide for an anode and a film of amorphous silicon nitride for a cathode for a solid electrolyte type secondary battery such that silicon compounds are adopted for the anode and cathode.SOLUTION: Adopted as a method for forming, at a high speed, a film of amorphous(non-crystal) SiC for an anode, and a film of amorphous(non-crystal) SiNfor a cathode on a substrate 6 having electrode leads of metal is a high-frequency(UHF band>300 MHz) film formation method by means of an atmospheric pressure plasma CVD(chemical vapor deposition). According to the method, an RF power source 10 of e.g. 550 MHz(UHF band) higher than a power source frequency generally used for plasma excitation is used to generate stable glow plasma 4, whereby high-density reaction species are produced and used. In this way, it becomes possible to generate high-density plasma in a small gap between the electrode 3 and the substrate 7 and thus, high-speed film formation can be achieved.

Description

The present invention relates to a high-frequency atmospheric pressure plasma chemical vapor deposition CVD method for a silicon compound electrode as a positive electrode and a negative electrode in a solid-state secondary battery that employs a silicon compound in a positive electrode and a negative electrode and a non-aqueous electrolyte between both electrodes. (Hereinafter abbreviated as CPD method).

In recent years, with the widespread use of portable devices such as personal computers and mobile phones, and automobiles and smart grids, the demand for secondary batteries serving as power sources for such devices has increased rapidly, and typical examples of such secondary batteries. Is a lithium battery using lithium (Li) as a negative electrode and carbon fluoride as a positive electrode. By interposing a nonaqueous electrolyte between the positive electrode and the negative electrode, it becomes possible to prevent extraction of metallic lithium. For this reason, lithium batteries are widely used. However, lithium is rare and expensive, and when it is discarded, lithium flows out, which is not preferable in the environment.

On the other hand, when silicon (Si), which is originally a semiconductor, is used as an electrode material, it is cheaper than lithium and silicon does not cause environmental problems such as outflow of metallic lithium. Attempts have been made to employ silicon as a material for electrodes of secondary batteries. According to Patent No. 4658192 of Patent Document 1, a secondary battery using silicon (silicon) has characteristics of silicon as compared with a lithium ion battery. If utilized, there is a possibility that durability can be realized with a large capacity. Instead of metal such as lithium used as an electrode of a secondary battery, silicon is used, silicon carbide is used for the positive electrode, silicon nitride is used for the negative electrode, and the electrolyte is used. Ion exchange resin was incorporated.

However, according to Japanese Patent No. 4658192 of Patent Document 1, after the positive electrode current collector layer is formed by metal sputtering on the substrate, the positive electrode layer is formed by vacuum deposition of silicon carbide on the positive electrode current collector layer, and then the positive electrode layer is not coated by coating. Since the negative electrode layer was formed by vacuum deposition of silicon nitride on the non-aqueous electrolyte layer after forming the water electrolyte layer, it was difficult to produce a strong amorphous (amorphous) electrode by vacuum deposition, and film formation It took time and money.

Conventional physical vapor deposition PVD includes vacuum vapor deposition, sputtering, ion plating, and other techniques, and the desired thin film can be obtained by controlling the degree of vacuum, substrate temperature, target composition, and power. Is an embodiment of the physical vapor deposition method, and in order to heat and deposit the metal to be deposited on the substrate surface in a decompressed space, approximately 10 ⁻³ to 10 ⁻⁵ Pa (Pascal = N / m ² ) It is housed in a bell jar that can be evacuated to a level of pressure, and the evaporation source is placed on a plate-like metal plate boat with a high melting point such as Mo. An electric current is applied and heated to 1000 ° C. or more, and the sample placed on top is melted and evaporated. Sputtering is also an aspect of physical vapor deposition, and it is possible to obtain a film of a high melting point material at a low temperature, to form a uniform film over a large area, to cope with an alloy composition, and to be fast and easy to control. It is widely used, and in rare cases, a rare gas such as argon is glow-discharged in a vacuum of about 10 ⁻⁰ to 10 ⁻² Pa, and the generated ions are accelerated in an electric field to collide with the target metal. Metal atoms are attached to the target substrate.

Chemical vapor deposition (CVD) is a film formation technique that is widely used in semiconductor manufacturing processes. In contact between a metal salt vaporized at a low temperature and a solid heated to a high temperature, thermal decomposition reaction, hydrogen reduction reaction, and high temperature disproportionation In this method, the target metal or metal compound is precipitated by reaction or the like. In order to easily and smoothly promote charge / discharge accompanied by generation of silicon ions (Si ⁺ and Si ⁻ ), it is preferable that each of the compounds has an amorphous state, that is, an amorphous structure instead of a crystal structure. Conventionally, a method of laminating both the negative electrode and the negative electrode by vacuum deposition has been adopted.

Plasma CVD (plasma-enhanced chemical vapor deposition, PECVD) is a type of chemical vapor deposition (CVD) that uses plasma and is one of the deposition methods for forming thin films of various materials. In order to activate the chemical reaction, the raw material gas is turned into plasma by applying a high frequency or the like, which is widely used for manufacturing semiconductor devices. It has many main advantages of chemical vapor deposition, such as a high deposition rate, a large processing area, and uniform film formation even on uneven surfaces. Furthermore, with the aid of plasma, a denser thin film can be formed even at low temperatures compared to thermal CVD, etc., and thermal damage and interdiffusion between layers can be suppressed. Can be obtained, and a thin film can be formed using raw materials having different thermal decomposition temperatures. In this plasma CVD, direct current (DC), high frequency (RF), microwaves, etc. are supplied to bring the source gas into a plasma state. As a result, the atoms and molecules of the source gas are excited and become chemically active. Plasma CVD has the following classification according to the excitation method. Conventional high-frequency plasma CVD is the most common plasma CVD because it can form an insulating thin film by using discharge at a high frequency of (13.56) MHz. Plasma CVD is generally operated by reducing the pressure inside the reaction chamber with a vacuum pump. In addition to oil rotary pumps and dry pumps, turbo molecular pumps and mechanical booster pumps may be used in combination. .

The atmospheric pressure plasma chemical vapor deposition CVD method (hereinafter abbreviated as CPD method) has a higher plasma density than vacuum plasma CVD, and has the advantage that a high-quality film can be formed at a lower temperature. Those operating at atmospheric pressure (normal pressure) are called atmospheric pressure plasma CVD. This plasma CPD method has been widely used especially for the formation of thin film silicon films, and is used in the manufacture of thin film transistor elements (TFTs) for flat displays such as liquid crystals and thin film silicon solar cells. It is also used for forming an interlayer insulating film. The atmospheric pressure plasma CVD method generates a stable glow plasma under atmospheric pressure with a high frequency of 150 MHz (VHF band), which is about an order of magnitude higher than the power supply frequency (13.56 MHz) generally used for plasma excitation. The film forming method utilizes reactive species generated at high density. By using this high-frequency power of 150 MHz, it is possible to generate high-density plasma in the small electrode of 0.1 to 1 mm and the gap between the substrates. The difference between atmospheric pressure VHF plasma and general low-pressure plasma is that the partial pressure of the source gas in the plasma can be increased, the collision frequency of atoms and molecules in the plasma is high, and the kinetic energy of charged particles is reduced. High temperature (including rotational temperature and vibration temperature) and efficient physical and chemical energy supply to the film growth surface. Therefore, if atmospheric pressure VHF plasma is used, high-speed film formation is possible in principle, ion damage of the film is reduced, and chemical reaction on the film growth surface is promoted even when the substrate temperature is low, High quality thin film formation can be expected. There are two types of electrodes that enable high-efficiency supply of reactive gases, stable control of atmospheric pressure plasma, and input of high power, such as a high-speed rotating electrode and a porous carbon electrode. The essential difference between these electrodes is It is a gas supply method to plasma. In the case of the high-speed rotating electrode in FIG. 2, the reaction gas in the atmosphere can be efficiently supplied to the electrode-substrate gap by rotating the cylindrical electrode at a high speed. On the other hand, in the case of the porous carbon electrode of FIG. 1, various high-purity process gases can be directly supplied into the plasma through the electrode.

Silicon carbide (SiC) has excellent physical properties such as about three times the band gap, about ten times the dielectric breakdown electric field strength, and about three times the thermal conductivity compared to Si. For example, if SiC is applied to a power semiconductor device, it is possible to reduce the heat loss during power conversion to about 1/100 or less that of a Si device as well as downsizing. Furthermore, the maximum operating temperature, which is about 150 ° C for Si, can be raised to 400-500 ° C.

Silicon nitride (SiNx) thin film has excellent properties such as high dielectric constant, high density, and high resistance to hydrofluoric acid etching, and is widely used as a mask material in thin film transistor (TFT) and oxide film formation. Yes. One of the typical methods for producing this SiNx thin film is the plasma CVD method using low-pressure plasma. However, since the absolute amount of reaction gas is small in the low-pressure process and a dramatic improvement in film formation speed cannot be expected, atmospheric pressure can be expected. We are developing technology for forming high-quality SiNx thin films on low-temperature substrates at high speed by using plasma CVD (CPD). SiHx and NH3 are used as source gases to form SiNx thin films, and the influence of deposition parameters such as source gas concentration (NH3 / SiH4 ratio), hydrogen concentration, input power, and substrate temperature on the film structure is being investigated.

According to Japanese Patent Laid-Open No. 2001-348665 of Patent Document 2, the present invention relates to an amorphous SiC thin film formed on a substrate by a high-speed film forming method using atmospheric pressure plasma CVD. Not only crystalline SiC but also amorphous Si _1-x C _x (a-Si _1-x C _x ) thin films can be controlled freely by their deposition parameters, so optoelectronic devices, solar cells, and light-emitting diodes Attempts have been made to apply to the above. Up to now, a-Si _1-x C _x thin film has been formed by RF sputtering method, plasma CVD method under reduced pressure, etc., but the film formation rate is slow, and the film formation rate is significantly increased. Amorphous SiC fabricated on a substrate by atmospheric pressure plasma CVD capable of forming a film at a speed 10 times or more higher than a film forming speed by a conventional film forming method such as an RF sputtering method or a plasma CVD method under reduced pressure. A thin film can be manufactured. This amorphous SiC thin film can also be provided as a semiconductor material for solar cells, light emitting diodes, and power devices. In order to solve the above-mentioned problems, a sample stage having a heating means and a cylindrical rotating electrode are disposed in an airtight chamber, and a predetermined gap is provided between the rotating electrode and the substrate is placed on the sample stage. The raw material gas of 0.1 to 10 atm including at least the carrier gas composed of the Si supply reaction gas, the C supply reaction gas, and the inert gas (Ar, He) introduced into the hermetic chamber is rotated at a high speed. Involved on the surface of the rotating electrode to form a gas flow across the gap, and a high-frequency voltage is applied to the rotating electrode to generate plasma in the gap to generate high-density radicals based on the reaction gas, which rotates with the sample stage. Amorphous Si by atmospheric pressure plasma CVD, characterized in that a SiC thin film is formed on a heated substrate by radical reaction while moving relative to the electrode In order to form an amorphous SiC thin film having excellent physical and electrical characteristics by forming a C thin film, it is necessary to optimally set various parameters. The frequency of the high frequency power supplied to the rotating electrode was 50 to 300 MHz. Here, normally, the hermetic chamber formed of a conductor is electrically grounded and has an earth potential, and plasma is generated and maintained in the gap between the rotating electrode and the substrate because of the difference in dielectric constant. Because of concentration. Further, the temperature of the substrate is set in the range of 300 to 500 ° C., and the film formation rate is set in the range of 15 to 40 nm / s. Then, the as a source gas, it is preferable formed by using a mixture of CH ₄ and SiH ₄ and H ₂ in the He, CH ₄ against further the He: 0.5 to 2 vol%, SiH _4: 0. It is better to use a mixture of 01 to 0.1% by volume and H ₂ : 0.5 to 2% by volume. FIG. 2 is a simplified explanatory view of a film forming apparatus according to the present invention, in which reference numeral 12 denotes a rotating electrode, 6 denotes a substrate, and 7 denotes a sample stage.
The hermetic chamber is a stainless steel container in which a sample stage holding a rotating electrode and a substrate is disposed. The rotating electrode is a cylindrical shape made of aluminum alloy having a diameter of 300 mm and a length of 100 mm, the surface of which is subjected to alumina spraying, and is rotated through a magnet coupling by a high-speed rotating motor 5 installed outside. The substrate is fixed on the sample stage by a vacuum chuck, and a film forming gap is formed between the substrate and the rotating electrode. The sample stage can be heated up to 600 ° C. in an atmospheric pressure He atmosphere by a built-in heater. The film formation gap is controlled by moving the stage up and down, and a thin film having an area corresponding to the moving distance can be formed by moving the stage in the front-rear direction. The power supply frequency is 150 MHz, and electric power is supplied to the electrode part via the impedance matching unit, and plasma is generated in the gap between the electrode and the substrate. By using 150 MHz as the power supply frequency, the vibration amplitude of charged particles is smaller than that of 13.56 MHz, which is mainly used in the conventional plasma CVD method. It can be decomposed and activated. Particles generated during film formation are discharged out of the film formation gap by a high-speed gas flow accompanying electrode rotation, but these particles can be efficiently recovered by circulation of process gas through a filter. .
As a result of observation of the prepared thin film with a transmission electron microscope, a broad halo pattern is observed from the transmission electron beam diffraction image, and no conspicuous contrast is seen from the bright field image. Therefore, the structure of the thin film may be amorphous. It could be confirmed. Since the cylindrical rotating electrode is used, the atmospheric pressure plasma generated between the electrode and the substrate spreads in the circumferential direction of the electrode around the position where the gap is the smallest. The magnitude of the plasma spread (plasma length) is about 20 to 30 mm, and varies depending on the film forming conditions (input power, reaction gas concentration, etc.). Therefore, the film formation speed is obtained from the time obtained by dividing the plasma length by the substrate scanning speed and the film thickness.

FIG. 3 shows the dependency of the CPD method on the input power density of the a-Si _1-x C _x deposition rate. When the input power density is 500 J / l or less, it is considered that the source gas (CH ₄ , SiH ₄ ) cannot be sufficiently decomposed and activated. When the input power density is 500 J / l or more, the deposition rate tends to decrease as the input power density increases. This is because the growth mechanism of the a-Si _1-x C _x thin film changes due to changes in the state and density of various radicals in the plasma, the temperature of the substrate surface, etc., as the input power density increases. This is considered to indicate that the structure of the Si _1-x C _x thin film has changed. According to the present invention, it is possible to realize the formation of a stoichiometric (Si: C = 1: 1) amorphous SiC thin film free from defects such as segregation and pinholes by setting film forming conditions optimally. The film was formed by high-speed film formation that was 10 times or more faster than the film formation speed of the film formation method.

In conventional plasma CVD (PECVD), the process temperature needed to be raised to around 400 ° C for high-quality film formation, so high-quality film formation at temperatures below 200 ° C was achieved, and high quality at low process temperatures. The purpose is high-speed CPD deposition of SiC and Si ₃ N ₄ electrodes, which enables uniform deposition of Si3N4.

Solid electrolyte secondary battery in which the positive electrode is silicon carbide having the chemical formula of SiC, the negative electrode is silicon nitride having the chemical formula of Si ₃ N ₄ , and a nonaqueous electrolyte is employed between the positive electrode and the negative electrode In order to manufacture the film by the CPD method, a process for forming amorphous (amorphous) SiC at the anode and amorphous (amorphous) Si ₃ N ₄ at the cathode at a high speed on the electrode lead metal base As described above, an amorphous silicon compound electrode of a silicon secondary battery can be formed by a high-frequency atmospheric pressure plasma chemical vapor deposition CVD method (hereinafter abbreviated as CPD method).

In order to enable the formation of amorphous silicon compound electrodes for silicon secondary batteries, the conventional power supply frequency of 13.56 MHz (RF band) used for plasma excitation, which is conventionally used, is an order of magnitude higher than the conventional 150 MHz (VHF band). ) Using a high-frequency 550 MHz (UHF band), generating stable glow plasma, and using a deposition method that uses reactive species generated at high density, It is possible to generate a high-density plasma in the gap.

In order to generate, for example, 550 MHz as a reference wave at a high frequency, the present inventor invented US patent 6952074 of Patent Document 3 as an ultra-small crystal resonator. The key points for successfully oscillating a directional high-frequency elastic wave at a single wavelength are the phenomenon of bending and dynamic pressure to form a groove-shaped concave-convex lens-shaped crystal object. This is due to the discovery of a design method that simultaneously processes the convex lens shape on the front surface and the concave lens shape on the back surface. In other words, we proposed a design method in which the central axis that is the convex lens-shaped machining axis and the central axis that is the concave lens-shaped machining axis can be formed simultaneously. As a result, the two central axes coincide completely naturally. In addition, a design method was proposed in which the optical axis of the crystal or the optical axis of rotation and the two central axes coincide completely. As a result, the vibration part of a single-sided grooved type having a two-stage shape is an extremely small concave-convex lens shape. A crystal unit with perfectly matched axes was completed. The crystal unit that has been successfully developed based on this design method is a very small concave-convex lens-shaped vibrating part with a convex lens shape on one side and a concave lens shape on the other side in a two-stage groove-type crystal base material. Have This vibration part vibrates in a thickness-shear vibration mode on the basis of appropriately designed upper and lower vapor deposition electrodes, and there is no spurious mode near the main vibration and an AT cut with a high Q value. A crystal oscillator can generate 550 MHz, for example, as a reference wave.
A sample crystal blank having a thickness of 90 μm, a vertical width of 3.58 mm, a horizontal width of 3.58 mm and a material of AT-cut was used. At the center of the quartz blank, first, a chemical etching process was performed using a hydrofluoric acid on a large area of a decagonal shape having a diameter of 1.6 mm and a depth of 57.0 μm, and a one-step shaped grooved A type quartz blank is processed. In the central part of the grooved type that is a 10-step shape in this one-step shape, a second chemical etching process is performed using hydrofluoric acid as the second processing step, and the diameter is 0.59 mm. Thus, a two-stage shape portion having a depth of 15.0 μm was formed. The single-sided grooved-type quartz blank with a two-stage shape, which was obtained by performing two chemical etching processes using hydrofluoric acid, was the first vibration with a circular area of 0.59 mm in a small area. When the portion is chemically etched, and then the second processing step is followed by a chemical etching process to produce a 10 mm square groove with a large area of 1.6 mm, the crystal anisotropy occurs, Since the crystal direction of the crystal is generated in the vibrating portion, it cannot be used as a crystal resonator at all. A single-sided grooved-type crystal resonator having a two-stage shape could be completed by a chemical etching processing method that is not normally considered. A quartz blank is sandwiched between the upper and lower polishing machines by applying a certain pressure, and polishing is performed using a dual-face polishing machine. As the polishing agent, when cerium oxide is used, the pressure distribution of the concave-shaped quartz blank sandwiched between the dual-face polishing machines is in order to sandwich the concave-shaped quartz blank by applying pressure between the upper and lower polishing discs. As indicated by the arrows, the frame portion receives pressure from both the upper and lower sides, but the opposite side of the vibration portion is hollow, and therefore receives pressure only from below. As a result, it bends upward with the centers of the decagonal groove portion and the circular vibration portion as vertices. Thus, the pressure is maximized at both ends, with the central portion being the minimum, by the amount of deflection that has escaped upward. Further, the polishing amount between the two parts changes with curvature like a part of the spherical surface. The polishing amount is proportional to the pressure. Therefore, it was clarified that the single-sided grooved-type quartz blank having a two-stage shape after processing protruded with the central portion of the vibration portion as a maximum and became a bulging convex lens shape. As a result, a plano-convex lens shape was completed.

In order to assemble a silicon secondary battery, a silicon carbide positive electrode having a chemical formula of SiC and a negative electrode of Si ₃ N ₄ silicon nitride formed on a lead metal were manufactured, and then a nonaqueous electrolyte was applied to each electrode. By applying and bonding, the silicon secondary battery can be quickly assembled and manufactured.

In conventional plasma CVD, the process temperature must be raised to around 400 ° C for high-quality film formation, but high-quality film formation at temperatures below 200 ° C has been achieved, and high quality and uniformity at low process temperatures. Capable of forming SiC and Si3N4 electrodes can be formed at high speed. In order to assemble a silicon secondary battery, a silicon carbide positive electrode having a chemical formula of SiC and a negative electrode of Si ₃ N ₄ silicon nitride formed on a lead metal were manufactured, and then a nonaqueous electrolyte was applied to each electrode. The silicon secondary battery can be rapidly manufactured by applying, bonding and bonding.

In order to form a sample 5 of a silicon compound comprising amorphous (amorphous) silicon carbide SiC as an anode and amorphous (amorphous) silicon nitride Si ₃ N ₄ as a cathode on a lead metal 6, A process gas 1 of SiH ₄ or methane CH ₄ and an inert carrier gas 8 are supplied to a confidential container 2, and a mixed gas flow 9 from the porous electrode 3 is generally plasma by an atmospheric pressure plasma chemical vapor deposition CVD method (CPD method). A stable glow using a high frequency power supply 10 of 550 MHz (UHF band) higher than the conventional 150 MHz (VHF band), which is one digit higher than the power supply frequency of 13.56 MHz (RF band) used for excitation. Plasma 4 is generated, and high-density plasma 4 is generated in a small gap of 0.1 to 1 mm between the temperature-controlled stage 1 and the porous electrode 3 and the substrate 7. In the porous carbon electrode of FIG. 1, various high-purity process gases can be directly supplied into the plasma through the electrode. There are two types of electrodes (high-speed rotating electrode and porous carbon electrode in FIG. 1) in order to enable high-efficiency supply of reactive gas, stable control of atmospheric pressure plasma, and input of high power. The difference between these electrodes is the gas supply method to the plasma. In the case of the high-speed rotating electrode shown in FIG. 2, by rotating the cylindrical electrode at a high speed, the reaction gas in the atmosphere is efficiently transferred to the gap between the electrode and the substrate. Can be supplied. Under the atmospheric pressure of the reaction gas, a strong electric field is locally formed between the two electrodes to generate plasma, and the object to be processed is irradiated with active species generated by the plasma. In the atmospheric pressure plasma processing apparatus that performs the process, the insulator causes a strong electric field to be formed at a specific position on the voltage application electrode side portion, thereby tilting the direction of the strong electric field with respect to the conveyance direction of the workpiece. Protrusions are provided. In the film formation method of the CPD method, a power supply in the UHF band (UHF band> 300 MHz) higher than the high frequency in the VHF band, which is one digit higher than the RF band of the power supply frequency used for conventional plasma excitation, is used. Since it is used, the silicon compound electrode of the silicon secondary battery can be quickly generated.

Conventional plasma CVD (PECVD) required the process temperature to be raised to around 400 ° C for high-quality film formation, but the CPD method shown in FIG. The film 5 can be realized by using the reaction gas 1 (silane SiH ₄ , methane CH ₄ ), and high quality silicon carbide SiC can be formed to meet the demand for low temperature in the CVD apparatus. Items such as film thickness, film stress, composition ratio, etch resistance, etc., formed using the PECVD apparatus shown in FIG. 1 were measured. In order to investigate the effect of heat, annealing (annealing) was performed at 600 ° C and compared with the sample before annealing. As a result, the deposition rate was 56 nm / s, and the film thickness was reduced by 20 nm in the sample after annealing. . It was also confirmed that the film stress transitioned from the compression region to the tensile region by annealing. When the composition was determined by EPMA, it was found that the ratio of Si to C decreased as the low-frequency LF component decreased, and increased as the LF component increased. The amount of C affected the film stress. I guess that. It was found that even an amorphous SiC film deposited at a low temperature using the high frequency (UHF band> 300 MHz) CPD method shown in FIG. 1 has sufficient etch resistance without losing chemical stability.

The high-speed continuous deposition PECVD apparatus of Si ₃ N ₄ thick film shown in FIG. 2 of the present invention is magnetically enhanced inductively coupled to the plasma source for controlling the film stress and controlling the film thickness uniformity. Coupled Plasma) can be used to handle up to large 8-inch wafers. As shown in FIG. 3, according to the CPD method of the present invention, the power supply frequency of 13.56 MHz (RF band) that is generally used for plasma excitation of the reaction gas 1 (SiH ₄ , ammonia NH ₃ ) is 150 times higher than that of the conventional 150 The high-frequency film-forming speed of MHz (VHF band) was about 6 times higher, but in the present invention, a higher 550 MHz (UHF band) power supply 10 is used, so the high-frequency (UHF band> 300 MHz) CPD method is used. As a result, a high-density plasma 4 can be generated in the gap between the electrode 3 and the substrate 7, and the film forming speed of the conventional RF band power supply is about 10 times faster than that. According to a drift-diffusion model calculation that can also be applied to plasma CVD, in the case of this reactive mixed gas, an amorphous Si ₃ N ₄ film can be optimally produced when the ammonia concentration is about 5 percent. Furthermore, in order to assemble a silicon secondary battery, a silicon carbide positive electrode having a chemical formula of SiC and a silicon nitride negative electrode having a chemical formula of Si ₃ N ₄ were formed on a lead metal. Thereafter, the silicon secondary battery can be rapidly manufactured by applying a nonaqueous electrolyte to each electrode and bonding them together. The production of large-capacity silicon secondary batteries has the advantage that they can be easily stacked in series because the current collecting leads of the approximately 4-volt unit batteries are metal foil plates.

With the widespread use of portable devices such as personal computers and mobile phones, and automobiles and smart grids, the demand for secondary batteries, which are the power sources of such devices, is rapidly increasing. Typical examples of such secondary batteries are lithium ( Although the lithium battery has Li) as a negative electrode and carbon fluoride or the like as a positive electrode, lithium is rare and expensive. When discarded, lithium flows out, which is not preferable in terms of environment. On the other hand, when silicon (Si), which is originally a semiconductor, is used as an electrode material, it is cheaper than lithium and silicon does not cause environmental problems such as outflow of metallic lithium. Attempts have been made to adopt silicon as a material for secondary battery electrodes, and secondary batteries using silicon electrodes have the potential to achieve high capacity and durability when utilizing the characteristics of silicon compared to lithium ion batteries. In this case, silicon carbide was used for the positive electrode, silicon nitride was used for the negative electrode, and an ion exchange resin was used for the electrolyte. The CPD method of the present invention generates a high-density plasma 4 because it uses a 550 MHz (UHF band) power supply 10 that is 40 times higher than the power supply frequency 13 MHz (RF band) generally used for plasma excitation. As a result, the film formation speed of the conventional RF band power supply is about 10 times faster. Further, in order to assemble a silicon secondary battery, after manufacturing a SiC positive electrode and a Si ₃ N ₄ negative electrode formed on a lead metal, a non-aqueous electrolyte is applied to each electrode, and the silicon secondary battery is laminated. A secondary battery can be manufactured quickly. For production of a large-capacity silicon secondary battery, the current collecting lead of the unit battery is a metal foil plate and can be easily stacked in series.

When a fine gas flow is used between the micro discharge electrodes, atmospheric pressure glow plasma can be stably generated. However, since the plasma exists between the micro electrodes of about 1 mm or less, applications using this are limited. In order to solve this problem, a method of extracting a plasma flow to the outside of the electrode by using an electrode having a circular opening and setting discharge conditions was examined. The phenomenon between the electrodes where power is injected and the region where the power is drawn out is deeply related to each other. Need to be established. In addition, it was shown that the micron-order plasma can efficiently inject energy with a higher power supply frequency, so that atmospheric pressure microplasma can be generated by high-frequency power and the plasma with high energy density can be extended outside the discharge electrode. Developments are also underway for the generation and use of different forms of electrical discharges obtained by controlling the hole diameter of electrodes for other industrial micromachining and surface treatment applications.

In the mass production process by the CPD method such as the latest advanced semiconductor devices (SiC, Si ₃ N ₄ ), in order to achieve high performance, a finer structure with better coverage, lower temperature and higher quality insulation film In order to provide a technique for forming the electrode (SiC, Si ₃ N ₄ ) at a lower cost, a highly productive process is essential. In order to overcome these problems, by developing a new film forming technique, it is possible to realize a process for forming an insulating film having a good coverage and a relatively high temperature at a relatively low temperature. A new high-frequency (UHF band> 300 MHz) CPD deposition system and process have been developed to obtain higher film thickness uniformity and higher composition controllability than conventional low-pressure CVD technology. Metal films and low-temperature silicon nitride films have been developed. Processes for such as have been developed. This technology is expected to solve many of the problems of next-generation memories and devices (SiC, Si ₃ N ₄ ). In the manufacturing process of SiC devices that are promising candidates for power devices, mass-production type high temperature (up to 800 ° C.) annealing equipment is required.

DESCRIPTION OF SYMBOLS 1 Reaction gas 2 Sealed container 3 Electrode 4 Plasma 5 Silicon compound film 6 Last power metal plate 7 Temperature control stage 8 Carrier gas 9 Process gas 10 High frequency power supply 11 Temperature control power supply 12 Rotating electrode

Claims (3)

Manufacture a silicon secondary battery that employs a non-aqueous electrolyte between the positive electrode and the negative electrode, with the positive electrode made of silicon carbide having the chemical formula of SiC and the negative electrode made of silicon nitride having the chemical formula of Si ₃ N ₄ In order to achieve this, a high-frequency (UHF) method is used to form amorphous (amorphous) SiC on the anode and amorphous (amorphous) Si ₃ N ₄ on the cathode at a high speed on the electrode lead metal base. A silicon compound characterized in that an amorphous silicon compound electrode of a silicon secondary battery can be formed by an atmospheric pressure plasma chemical vapor deposition CVD method (hereinafter abbreviated as a CPD method) using a band> 300 MHz) Electrode manufacturing method and manufacturing apparatus. In claim 1, in order to make it possible to form a CPD film of an amorphous silicon compound electrode of a silicon secondary battery, the conventional power supply frequency of 13.56 MHz (RF band) used for plasma excitation, which has been conventionally used, is an order of magnitude higher Using a UHF band of 300 MHz or higher, which is higher than the 150 MHz (VHF band) high frequency, a stable glow plasma is generated, and a deposition method using reactive species generated at high density is adopted. The silicon compound electrode film-forming method and film-forming apparatus are capable of generating high-density plasma in a small gap between electrode substrates. 2. A silicon carbide positive electrode having a chemical formula of SiC, formed by using a high frequency CPD method on the surface of a lead metal plate in claim 2 to assemble a silicon secondary battery, and Si _{3. A} method for manufacturing a silicon secondary battery, comprising manufacturing a negative electrode of ₃ N ₄ and then applying and bonding a nonaqueous electrolyte to each electrode.