Discharge cell, ozone gas generator, and method for manufacturing discharge cell

Abstract

A discharge cell (24) for generating ozone gas by silent discharge according to the present disclosure is provided with: a pair of electrodes (31) facing each other; at least one dielectric body (32) which is disposed between the pair of electrodes (31) facing each other; a discharge gap (G) which is formed between the electrodes (31) and the dielectric body (32) or between a pair of dielectric bodies (32), and through which an oxygen gas passes; and a functional film (33) which covers the surface of the dielectric body (32) on the discharge gap (G) side and suppresses separation of the discharge cell due to silent discharge. The thickness of the functional film is 6 μm or more. At least the surface of the functional film on the discharge gap side is composed only of an amorphous component, and a crystalline component is not exposed to the discharge gap.

Description

Discharge cell, ozone gas generator, and method for manufacturing a discharge cell

[0001] The present invention relates to a discharge cell, an ozone gas generator, and a method for manufacturing a discharge cell.

[0002] Ozone gas generators, which produce ozone gas using oxygen gas as a raw material, are widely used in semiconductor manufacturing processes and other applications.

[0003] Patent Document 1 discloses an ozone gas generator having a silent discharge type discharge cell. In the discharge cell, dielectric materials are stacked on the inside of a pair of electrodes connected to a power source. When a voltage is applied to the pair of electrodes from the power source, silent discharge occurs in the discharge gap between the dielectric materials, and ozone gas is generated. Patent Document 1 improves performance by forming a functional film on the discharge gap side of the dielectric material.

[0004] Japanese Patent Publication No. 2011-051865

[0005] In the manufacturing of semiconductor devices, particularly when using ozone gas for cleaning silicon wafers, the removal of impurities from the generated ozone gas is especially important depending on the intended use.

[0006] The purpose of this disclosure is to suppress the generation of impurity particles in a discharge cell that generates ozone gas.

[0007] The discharge cell of this disclosure is a discharge cell that generates ozone gas by silent discharge, and comprises a pair of opposing electrodes, at least one dielectric disposed between the pair of opposing electrodes, a discharge void formed between the electrodes and the dielectric, or between a pair of dielectrics, through which oxygen gas passes, and a functional film that covers the surface of the dielectric facing the discharge void and suppresses the peeling of the discharge cell by silent discharge. The thickness of the functional film is 6 μm or more, and at least the surface of the functional film facing the discharge void consists only of amorphous components, with no crystalline components exposed to the discharge void.

[0008] The ozone gas generator of this disclosure comprises the above-mentioned discharge cell and an oxygen supply source that supplies oxygen with a purity of 99.9% or higher to the discharge cell.

[0009] The method for manufacturing a discharge cell according to this disclosure comprises the steps of forming a first material film on one surface of a dielectric by screen printing, and firing the first material film to form a functional film that suppresses peeling of the discharge cell due to silent discharge. At least the surface of the functional film on the discharge void side consists only of amorphous components, and the crystalline components are not exposed to the discharge void.

[0010] According to this disclosure, it is possible to suppress the inclusion of particles as impurities in the generated ozone gas.

[0011] Figure 1 is a schematic diagram illustrating the ozone gas generator of the present disclosure. Figure 2 is a schematic cross-sectional view of the ozone gas generation unit of the present disclosure, particularly its discharge cell. Figure 3 is a cross-sectional view corresponding to line III-III in Figure 2. Figure 4 is a cross-sectional view corresponding to line IV-IV in Figure 3. Figure 5 is a diagram illustrating the manufacturing method of the discharge cell of the present disclosure. Figure 6 is a schematic cross-sectional view of a modified discharge cell of the present disclosure.

[0012] The embodiments will be described below with reference to the drawings. The following description is illustrative and not limiting. Furthermore, modifications can be made as appropriate within the scope of achieving the desired effect.

[0013] (Ozone Gas Generator) Figure 1 is a schematic diagram showing the ozone gas generator (20) of the present disclosure. The ozone gas generator (20) comprises a raw material gas supply unit (21), an ozone gas generation unit (22), and an ozone gas extraction unit (23).

[0014] A raw material gas is supplied to the raw material gas supply unit (21). A supply pipe (not shown) is connected to the raw material gas supply unit (21). The raw material gas supply unit (21) is connected to a raw material gas supply source such as a gas cylinder via the supply pipe. High-purity oxygen gas (99.9% or higher) is used as the raw material gas. In the ozone gas generator (20) of this disclosure, it is preferable to add a certain amount of water (about 50 to 1000 ppm) to the raw material gas using a gas conditioner (not shown) in order to stably generate ozone gas.

[0015] The ozone gas generation unit (22) is supplied with raw material gas from the raw material gas supply unit (21). In the ozone gas generation unit (22), ozone gas is generated from oxygen gas through silent discharge. Details of the ozone gas generation unit (22) will be described later.

[0016] The ozone gas extraction unit (23) supplies the ozone gas generated in the ozone gas generation unit (22) to the outside. Extraction piping (not shown) is connected to the ozone gas extraction unit (23). The ozone gas extracted from the extraction piping is dissolved in, for example, pure water to produce ozonated water. This ozonated water is used, for example, to clean silicon wafers in semiconductor manufacturing equipment.

[0017] (Details of the ozone gas generation unit) Figure 2 is a schematic cross-sectional view of the ozone gas generation unit (22). Figure 3 is a cross-sectional view corresponding to line III-III in Figure 2, and Figure 2 is a cross-sectional view corresponding to line II-II in Figure 3. Also, Figure 4 is a cross-sectional view corresponding to line IV-IV in Figure 3. However, all are schematic diagrams, and dimensions, ratios, etc. do not necessarily correspond, nor do they necessarily reflect the actual dimensions.

[0018] As shown in Figure 2, the ozone gas generation unit (22) comprises a silent discharge type discharge cell (24) and a power supply (25) connected to the discharge cell (24). The discharge cell (24) has a high-pressure side electrode unit (30A) and a low-pressure side electrode unit (30B). Since the configuration of the high-pressure side electrode unit (30A) and the low-pressure side electrode unit (30B) is basically the same, they are sometimes collectively referred to as the electrode unit (30). The discharge cell (24) comprises at least one pair of such opposing electrode units (30).

[0019] As shown in Figures 3 and 4, the high-pressure side electrode unit (30A) and the low-pressure side electrode unit (30B) are insulated from each other by an insulating partition member (40). A discharge gap (G) through which oxygen gas flows is formed between the high-pressure side electrode unit (30A) and the low-pressure side electrode unit (30B). The high-pressure side electrode unit (30A) is the electrode unit on the high-pressure side, and the low-pressure side electrode unit (30B) is the electrode unit on the ground side (low-pressure side).

[0020] The power supply (25) is composed of a high-frequency high-voltage power supply. The high-voltage side electrode unit (30A) has a high-voltage side electrode (31A), a high-voltage side dielectric (32A), and a high-voltage side functional film (33A), which are stacked sequentially in the thickness direction. The low-voltage side electrode unit (30B) has a low-voltage side electrode (31B), a low-voltage side dielectric (32B), and a low-voltage side functional film (33B), which are stacked sequentially in the thickness direction.

[0021] The high-voltage side electrode (31A) and the low-voltage side electrode (31B) are electrically connected to the power supply (25). The high-voltage side electrode (31A) and the low-voltage side electrode (31B) are formed in the shape of a plate or a film. The high-voltage side electrode (31A) and the low-voltage side electrode (31B) are positioned opposite each other with a discharge gap (G) in between.

[0022] The high-pressure side dielectric (32A) is formed on the discharge gap (G) side surface (lower surface in Figure 2) of the high-pressure side electrode (31A). The low-pressure side dielectric (32B) is formed on the discharge gap (G) side surface (upper surface in Figure 2) of the low-pressure side electrode (31B). The high-pressure side dielectric (32A) and the low-pressure side dielectric (32B) are formed in a plate shape. The high-pressure side dielectric (32A) and the low-pressure side dielectric (32B) are made of an insulating material such as alumina. The high-pressure side dielectric (32A) may cover the high-pressure side electrode (31A). Similarly, the low-pressure side dielectric (32B) may cover the low-pressure side electrode (31B).

[0023] Furthermore, since the configurations of the high-pressure side dielectric (32A) and the low-pressure side dielectric (32B) are basically the same, they are sometimes collectively referred to as dielectric (32). Similarly, the high-pressure side electrode (31A) and the low-pressure side electrode (31B) are sometimes collectively referred to as electrode (31).

[0024] The dielectric (32) is formed in the shape of a rectangular plate. The dielectric (32) may be obtained by firing high-purity alumina. The thickness of the dielectric (32) is preferably 0.05 to 0.9 mm.

[0025] A pair of opposing side edges of the dielectric (32) (the upper and lower side edges in Figure 3) each have an opening (an inlet (51) and an outlet (52)). The lower opening in Figure 3 is the inlet (51), and the upper opening in Figure 3 is the outlet (52). The inlet (51) and outlet (52) extend along the side edges of the dielectric (32) and penetrate the dielectric (32) in the thickness direction. The inlet (51) communicates with the raw material gas supply unit (21). The outlet (52) communicates with the ozone gas extraction unit (23).

[0026] Cooling passages (45) for cooling the ozone gas generation unit (22) are formed in the other pair of side edges of the dielectric (32) (the left and right side edges in Figure 3). The cooling passages (45) penetrate the dielectric (32) in the thickness direction, and the ozone gas generation unit (22) is cooled by the flow of a coolant through them.

[0027] A partition member (40) is provided inside the dielectric (32). The partition member (40) is made of an insulating material such as a glass-based material. The partition member (40) has a rectangular frame portion (41) along the outer edge of the dielectric (32) and a plurality of ribs (42) that extend linearly across the inlet (51) and outlet (52). The plurality of ribs (42) are arranged parallel to each other along the longitudinal direction of the inlet (51) and outlet (52) so as to be equally spaced from each other.

[0028] The high-pressure side electrode unit (30A) and the low-pressure side electrode unit (30B) are joined together by the top surfaces (42A) of their opposing frame portions (41) and ribs (42) via an adhesive layer (63). This creates a discharge gap (G) between the high-pressure side electrode unit (30A) and the low-pressure side electrode unit (30B). The discharge gap (G) communicates with the inlet (51) and outlet (52). The sides of the discharge gap (G) are sealed except for the inlet (51) and outlet (52) by the ribs (42) or frame portions (41) acting as side walls.

[0029] In such a discharge void (G), oxygen gas flows in the direction of the white arrow in Figure 3. The spacing of the discharge voids (G) is preferably 60 μm or more and 100 μm or less.

[0030] The high-voltage side functional film (33A) is formed on the surface (the lower surface in FIG. 2) of the high-voltage side dielectric (32A) on the discharge gap (G) side. The low-voltage side functional film (33B) is formed on the surface (the upper surface in FIG. 2) of the low-voltage side dielectric (32B) on the discharge gap (G) side. Since the configurations of the high-voltage side functional film (33A) and the low-voltage side functional film (33B) are basically the same, they may be collectively referred to as the functional film (33). The functional film (33) is formed in a plate shape or a film shape. Further, the functional film (33) is also formed so as to cover the side surfaces of the ribs (42) or the frame portion (41) that serve as side walls of the discharge gap (G).

[0031] The functional film (33) is formed as a film in which at least the surface on the discharge gap (G) side consists only of an amorphous component. A glass component may be used as the amorphous component. For the purpose of stably generating ozone gas, the functional film (33) may contain boron, zirconium, titanium oxide, or the like. For example, SiO ２ is used as a main component (59 to 79% by mass), and TiO ２ is contained in an amount of 10 to 20% by mass, B ２ O ３ is contained in an amount of 10 to 20% by mass, and ZrO ２ may be contained in an amount of about 1% by mass.

[0032] The discharge gap (G) is formed between the lower surface of the high-voltage side functional film (33A) and the upper surface of the low-voltage side functional film (33B). In other words, the high-voltage side functional film (33A) and the low-voltage side functional film (33B) form surfaces exposed to the discharge gap (G). Oxygen gas flows into the upstream side of the discharge gap (G) (for example, the left side in FIG. 2). When a high-frequency alternating voltage is applied from a power supply (25) to the high-voltage side electrode (31A) and the low-voltage side electrode (31B), silent discharge occurs in the discharge gap (G). A large amount of electrons excited by the discharge generate oxygen radicals such as oxygen atoms, and consequently ozone gas is generated. The ozone gas generated in the discharge gap (G) flows out to the downstream side (for example, the right side in FIG. 2).

[0033] When generating ozone gas by such silent discharge, if the dielectric (32) is exposed to the discharge gap (G), this causes the generation of particles. In other words, since the dielectric (32) is made of crystalline alumina or the like, the surface is damaged by the discharge and peels off in the form of particles, which causes the generation of particles.

[0034] In contrast to the above, in the ozone gas generation unit (22) of the present embodiment, a functional film (33) is formed so as to cover the dielectric (32). The functional film (33) is formed such that at least the surface on the discharge gap (G) side is formed of a film consisting only of an amorphous component, and no crystalline component is exposed to the discharge gap (G). Accordingly, particulate peeling does not occur, and the generation of particles can be suppressed.

[0035] From the viewpoint of exerting the effect of suppressing particle generation, the functional film (33) desirably has a film thickness of 6 µm or more. Further, from the viewpoints of the ozone gas generation function and the manufacturing of the device, the film thickness of the functional film (33) is preferably 20 µm or less.

[0036] It should be noted that a configuration in which the electrode unit (30) does not include the dielectric (32) and enamel processing is performed on a metal electrode plate is also conceivable. In this case, the film thickness of the enamel processing needs to be larger than that of the functional film (33) of the present disclosure, and is, for example, approximately 300 to 1000 µm.

[0037] The dielectric strength of the dielectric (32) made of a material such as alumina is higher than that of an amorphous film such as glass. Therefore, the configuration of the present disclosure, in which the dielectric (32) is provided on the electrode (31) made of metal and the functional film (33) is provided on the surface thereof, the risk of dielectric breakdown is greatly reduced compared to a configuration in which enamel processing is performed on a metal electrode plate.

[0038] Furthermore, the discharge cell (24) is cooled using the cooling passage (45) to cope with the heat generated by the discharge. In this case, it is desirable that the discharge cell (24) has a high thermal conductivity in order to improve the cooling efficiency. The thermal conductivity of the dielectric (32) made of alumina or the like is higher than that of the amorphous film formed on the metal electrode plate by enamel processing, so the discharge cell (24) of this disclosure has better cooling efficiency than a configuration in which enamel processing is applied to the metal electrode plate. The manufacturing method of the discharge cell (24) of this disclosure will be described later.

[0039] Furthermore, in the configuration of this disclosure, which includes an electrode (31), a dielectric (32), and a functional film (33), the thickness of each layer can be reduced, and from this point of view, the cooling efficiency is superior to that of a configuration in which an enamel coating is applied to a metal electrode plate.

[0040] Furthermore, in order to improve the efficiency of ozone gas generation, it is desirable to narrow the discharge gap (G). In order to achieve a narrow discharge gap (G), it is necessary to increase the flatness of the surface of the electrode unit (30) that constitutes the discharge gap (G). In this regard, it is easier to control the flatness by printing a functional film on a dielectric sheet by screen printing. Therefore, the configuration of the present disclosure, in which a thin functional film (33) is formed on a dielectric (32), is advantageous in terms of precision control of flatness compared to the conventional configuration in which an amorphous film is formed on a metal electrode plate.

[0041] (Method for Manufacturing a Discharge Cell) Next, a method for manufacturing the discharge cell (24) of the present disclosure will be described. Figure 5 is an example of a method for manufacturing one electrode unit (30) in the discharge cell (24), and shows steps A to E individually. These figures are cross-sectional views showing the area that crosses the two ribs (42) in Figure 3.

[0042] In step A, a partition member (40) is formed on one surface of the dielectric (32). The dielectric (32) is cut from a sheet of dielectric material, with the outer shape of the discharge cell (24) and through holes corresponding to the cooling passage (45), inlet (51), and outlet (52). This one surface is the surface facing the discharge gap (G) in the discharge cell (24). Figure 5 shows the rib (42) portion of the partition member (40).

[0043] The dielectric (32) may be made of fired alumina. The thickness of the dielectric (32) is preferably 0.9 mm or less. The rib (42) is formed by forming a material film containing a glass-based material on the surface of the dielectric (32) by screen printing, firing the film, and then polishing an excess portion. The rib (42) has a rectangular cross-section having a polished top surface (42A) and side surfaces (42B).

[0044] Next, in the step B, a first material film (33C) is formed on the surface of the dielectric (32) on which the rib (42) is formed. The first material film (33C) is formed to avoid the top surface (42A) of the rib (42) and cover the surface of the dielectric (32) and the side surfaces (42B) of the rib (42). This can be achieved by screen printing. In this process, a mask having an opening at a portion where the first material film (33C) is to be formed is used.

[0045] The first material film (33C) is made of a material that, after firing, forms a film in which at least the surface on the discharge gap (G) side is composed of an amorphous component, for example, a material containing a glass component. The first material film (33C) may contain materials other than the glass component, for example, boron oxide (B ２ O ３ ) in an amount of 10 to 20% by mass, titanium oxide (TiO ２ ) in an amount of 10 to 20% by mass, and zirconium oxide (ZrO ２ ) in an amount of 0.5 to 1.5% by mass. By firing, boron oxide becomes amorphous similarly to the glass component, while titanium oxide and zirconium oxide become crystalline.

[0046] For appropriate screen printing, it is desirable that the particle size of the material has a median diameter (D50) in a range of 7 to 10 µm, for example. Further, it is desirable that the viscosity of the material paste used for screen printing is in a range of 100 to 250 Pa·s (at 25±1°C, 10 rpm).

[0047] Next, in step C, an electrode (31) is formed in a predetermined region on the other surface of the dielectric (32) (the surface opposite to the rib (42) and the first material film (33C) (the surface opposite to the discharge gap (G) in the discharge cell (24))). The electrode (31) may be formed using a metallic material such as Ag+Pd, W, Pt, or Au. CVD (chemical vapor deposition), plating, etc., can be used as the formation method.

[0048] Next, in step D, a second material film (34A) is formed on the other surface of the dielectric (32), including the area over the electrode (31). That is, the second material film (34A) is formed so as to cover the portion of the dielectric (32) that is exposed and where the electrode (31) is not formed, and the area over the electrode (31). The second material film (34A) can also be formed, for example, by screen printing.

[0049] The second material film (34A) is a film made of a material that becomes the adhesive layer (34) by firing, and is, for example, a film of a material containing a glass component. Here, both the first material film (33C) and the second material film (34A) may be made of a material containing a glass component, but it is preferable that their compositions are different. The second material film (34A) is, for example, SiO ２ The main component is (60-70% by mass), Al ２ O ３ 1 to 10% by mass, B ２ O ３ It may also contain 10 to 20% by mass of [the substance]. Using such a formulation, the inclusion of Al2O3 makes it possible to bring the coefficient of thermal expansion closer to that of the dielectric (32) made of alumina.

[0050] Next, in step E, firing is performed. At this time, the first material film (33C) and the second material film (34A) are fired simultaneously to form a functional film (33) and an adhesive layer (34), respectively. In this case, if the first material film (33C) consists only of glass components, a functional film is formed in which not only the surface on the discharge void (G) side but the entire structure consists only of amorphous components. Furthermore, if the first material film (33C) consists not only of glass components but also of boronium oxide (B) ２ O ３ ) 10-20% by mass, titanium oxide (TiO２ ) 10 to 20% by mass, zirconium oxide (ZrO ２ When it contains 0.5 to 1.5% by mass of titanium oxide (TiO), during firing, titanium oxide (TiO) becomes a crystalline component. ２ ) and zirconium oxide (ZrO ２ ) sinks into the dielectric (32) side. This is because titanium oxide (TiO ２ ) and zirconium oxide (ZrO ２ The specific gravity of the amorphous components (glass material and boronium oxide (B) ２ O ３ This is because its specific gravity is greater than that of the other components. Therefore, after firing, the amorphous components with a lower specific gravity are present on the surface, and a functional film (33) consisting only of amorphous components is formed on the surface at least on the discharge void (G) side.

[0051] Next, a pair of structures shown in E are prepared, and the same adhesive material as the second material film (34A) is screen printed onto the top surface (42A) of each rib (42) and fired. The top surfaces of the ribs (42) are then heated facing each other with this adhesive material in between, and bonded together. As a result, a discharge cell (24) consisting of a pair of electrode units (30) is formed, as shown in Figures 2 and 4. At the same time, each electrode unit (30) is bonded to other components such as cooling channel members and other discharge cells via the adhesive layer (34), creating a multi-stage structure.

[0052] As described above, the thickness of the functional film (33) is preferably 6 μm or more and 20 μm or less. Such thinness is difficult to achieve by methods such as spray coating. In contrast, in this embodiment, the above thickness can be achieved by forming the first material film (33C) using screen printing.

[0053] In the above explanation, the process of forming a first material film (33C) on one surface of the dielectric (32) (step B in Figure 5) is followed by the process of forming a second material film (34A) on the other surface (step D in Figure 5). However, this order can be reversed. In other words, the second material film (34A) may be formed first, and then the first material film (33C) may be formed.

[0054] The dielectric (32), made of alumina or the like, and the first material film (33C) or second material film (34A), made of a material containing glass components, have different coefficients of thermal expansion due to the difference in materials. Therefore, as shown in Figure 5, it is desirable to perform firing with the first material film (33C) and the second material film (34A) formed on both sides of the dielectric (32), respectively. In this way, the first material film (33C) and the second material film (34A), although their compositions are different, have similar coefficients of thermal expansion, so when fired simultaneously, both sides of the dielectric (32) expand and contract to the same extent. As a result, warping caused by the difference in the coefficients of thermal expansion of each layer can be suppressed, and firing can be performed while maintaining flatness.

[0055] However, the formation of a functional film (33) in which at least the surface on the discharge void (G) side consists only of amorphous components can be achieved by firing the dielectric (32) with the first material film (33C) formed on one side. In other words, the functional film (33) may be formed by firing after steps A and B in Figure 5, without performing steps C and D.

[0056] Even in this manner, depending on the thickness and material of the dielectric (32) and the first material film (33C), for example, if the first material film (33C) is formed thinly using screen printing as in this embodiment, it may be possible to suppress the occurrence of warping.

[0057] (Modifications concerning the discharge cell) Figure 6 is a diagram showing an ozone gas generation unit (22A) of a modification of the present disclosure, and corresponds to Figure 2. Figure 2 shows a discharge cell (24) comprising a high-pressure side electrode unit (30A) and a low-pressure side electrode unit (30B) having similar structures. Each electrode unit (30) in Figure 2 comprises an electrode (31), a dielectric (32), and a functional film (33).

[0058] In contrast, in the discharge cell (24A) of Figure 6, the high-voltage side electrode unit (30A) is the same as that in Figure 2, but the low-voltage side electrode unit (30D) does not have a dielectric and a functional film, and consists of a low-voltage side electrode (31B). The power supply (25) is connected to the discharge cell (24A) as in Figure 2.

[0059] Thus, the discharge cell (24A) may be configured to include a pair of opposing electrodes (31), a dielectric (32) placed between them, a discharge gap (G) in the dielectric (32), and a functional film (33) covering the surface of the dielectric (32) on the discharge gap (G) side.

[0060] In this modified example, the functional film (33) is formed as a film in which at least the surface on the discharge void (G) side consists only of amorphous components. As a result, even in the discharge cell (24A) of this modified example, the generation of particles when generating ozone gas can be suppressed.

[0061] Each embodiment described above may be modified in form or detail without departing from the spirit of the claims. Furthermore, the contents of each embodiment may be combined and substituted as appropriate, as long as they do not impair the functions covered by this disclosure.

[0062] According to this disclosure, it is possible to realize a discharge cell for generating ozone gas that can suppress the generation of particles, and this is useful as an ozone gas generating discharge cell and a method for manufacturing the same.

[0063] 20 Ozone gas generator 21 Raw material gas supply unit 24 Discharge cell 24A Discharge cell 31 Electrode 32 Dielectric 33 Functional film 33C First material film 34 Adhesive layer 34A Second material film 42 Rib 42A Top surface 42B Side surface G Discharge gap

Claims

1. A discharge cell for generating ozone gas by silent discharge, comprising: a pair of opposing electrodes; at least one dielectric disposed between the pair of opposing electrodes; a discharge void formed between the electrodes and the dielectric, or between a pair of the dielectrics, through which oxygen gas passes; and a functional film covering the surface of the dielectric facing the discharge void and suppressing the peeling of the discharge cell by the silent discharge, wherein the thickness of the functional film is 6 μm or more, and at least the surface of the functional film facing the discharge void consists only of amorphous components, with no crystalline components exposed to the discharge void.

2. The discharge cell according to claim 1, wherein the discharge void comprises an inlet for the oxygen gas and an outlet for the generated ozone gas, and a side wall that seals the sides except for the inlet and the outlet, and the side wall is covered with the functional film.

3. The discharge cell according to claim 1, characterized in that the thickness of the functional film is 20 μm or less.

4. The discharge cell according to claim 1, characterized in that the thickness of the dielectric is 0.9 mm or less.

5. An ozone gas generator comprising a discharge cell according to claim 1 and an oxygen supply source that supplies oxygen with a purity of 99.9% or higher to the discharge cell.

6. A method for manufacturing a discharge cell that generates ozone gas by silent discharge, comprising the steps of: forming a first material film on one surface of a dielectric by screen printing; and firing the first material film to form a functional film that suppresses peeling of the discharge cell by silent discharge, wherein at least the surface of the functional film on the discharge void side consists only of amorphous components, and the crystalline components are not exposed to the discharge void.

7. The method for manufacturing a discharge cell according to claim 6, further comprising the steps of: forming an electrode on a part of the other surface of the dielectric; and forming a second material film having a different composition from the first material film on the other surface of the dielectric, including the electrode, wherein in the step of forming the functional film, the second material film is fired simultaneously with the first material film to form an adhesive layer, and the functional film and the adhesive layer have different compositions.

8. The method for manufacturing a discharge cell according to claim 6, further comprising the step of forming a rib having a top surface and side surfaces on one surface of the dielectric before the step of forming the first material film, wherein the first material film is screen printed on one surface of the dielectric and the side surfaces of the rib, avoiding the top surface of the rib.

9. The method for manufacturing a discharge cell according to claim 6, characterized in that the functional film is formed to a thickness of 6 μm or more.

10. The method for manufacturing a discharge cell according to claim 6, characterized in that the functional film is formed to a thickness of 20 μm or less.

11. The method for manufacturing a discharge cell according to claim 6, characterized in that the thickness of the dielectric is 0.9 mm or less.

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