JP2014186898A - Method of manufacturing discharge element and discharge element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a discharge element in which adjustment of electrode spacing is not required, and production cost of ozone never increase and to provide a discharge element.SOLUTION: A discharge element 1 includes a pair of discharge electrodes 3A, 3B facing each other via a discharge gap 12 and an insulating substrate 2 supporting the pair of discharge electrodes 3A, 3B. A method of manufacturing the discharge element 1 includes a gap formation step for forming a through hole 12, to be used as a discharge gap, in an electrode plate 51 and bringing the pair of discharge electrodes into a state connected each other partially, a bonding step for bonding one side of the electrode plate 51 provided with the through hole 12 to the insulating substrate 2, and a dicing step for dividing the electrode plate 51 bonded to the insulating substrate 2, and generating a discharge element 1 in a state where the pair of discharge electrodes 3A, 3B are separated.

Description

  The present invention relates to a method for manufacturing a discharge element that generates plasma by discharge under atmospheric pressure, and a discharge element.

  Conventionally, in order to perform sterilization, sterilization, deodorization, and the like using ozone, an ozone generator that generates ozone by discharging at atmospheric pressure has been used. As this type of ozone generator, there is a dielectric barrier type (see, for example, Patent Document 1).

  Dielectric barrier ozone generators are opposed to each other at regular intervals in a space, and an alternating high voltage is applied between a pair of electrodes provided with a dielectric on the surface to generate plasma. By this plasma, oxygen in the air is decomposed and combined to generate ozone.

Japanese Patent No. 4320637

  The conventional dielectric barrier ozone generator is adjusted by moving the electrodes so that the distance between the electrodes is constant. However, it is necessary to adjust the distance between the electrodes to a minute value such as 0.03 mm, and there is a problem that adjustment is difficult and the distance varies. Increasing the distance between the electrodes reduces the influence of variations in the distance, but it is necessary to increase the discharge start voltage. In order to increase the discharge starting voltage, the scale of the driving power source for the ozone generator must be increased, which increases the cost of the power source. Therefore, the production cost of ozone increases.

  Accordingly, an object of the present invention is to provide a discharge element manufacturing method and a discharge element that do not require adjustment of the electrode interval and do not increase the cost of generating ozone.

  The present invention is a method for manufacturing a discharge element, comprising a pair of discharge electrodes opposed via a discharge gap, and an insulating substrate supporting the pair of discharge electrodes. This manufacturing process includes a gap forming process, a bonding process, and a dicing process. In the gap forming step, a through hole used as a discharge gap is formed in the electrode plate, and the pair of discharge electrodes are partially connected to each other. In the joining step, one surface of the electrode plate provided with the through hole is joined to the insulating substrate. In the dicing step, the electrode plate bonded to the insulating substrate is divided to generate a discharge element in which the pair of discharge electrodes are separated.

  In this invention, a through-hole is provided in the electrode plate, and this is used as a discharge gap. Further, after the electrode plate having the discharge gap formed is joined to the insulating substrate, the pair of discharge electrodes are separated. Since it is divided into states, the discharge gap does not change before and after the division of the electrode plate. Therefore, in the gap forming step, by providing a discharge gap having a desired interval in the electrode plate, adjustment of the electrode interval is not necessary in the manufacturing process. Thereby, the scale of the drive power supply of an ozone generator can be made small, and generation costs of ozone, such as the expense of a power supply and power consumption, can be controlled.

  In the above invention, a cavity forming step is provided before the gap forming step. In the cavity forming step, a cavity is provided on one surface of the electrode plate.

  In the present invention, after forming the cavity in the electrode plate, the discharge gap is formed in the cavity, thereby reducing the thickness of the electrode plate in the portion where the discharge gap is formed. Can be shortened.

  In the above invention, a film forming step is provided between the gap forming step and the bonding step. In the film forming step, the electrode plate is covered with a thermal oxide film.

  In the present invention, after the step of coating the pair of discharge electrodes with the thermal oxide film, the pair of discharge electrodes with the thermal oxide film is attached to an insulating substrate having a low temperature resistance. As a result, the thermal oxide film can be formed dense and free of voids without adversely affecting the insulating substrate.

  In the above invention, an opening forming step and a metal electrode forming step are provided between the bonding step and the dicing step. In the opening forming step, a plurality of openings through which the electrode plate is exposed are formed in the vicinity of the discharge gap of the electrode plate. In the metal electrode formation step, metal electrodes are formed in the plurality of openings.

  In the present invention, before the electrode plate bonded to the insulating substrate is divided, the openings and the metal electrodes are collectively formed for the plurality of discharge elements. Thus, the discharge element can be manufactured efficiently.

  The discharge element of the present invention includes an insulating substrate, a discharge electrode portion opposed via a discharge gap, and a pair of discharge electrodes each having a bonding portion bonded to the insulating substrate. Separated from the insulating substrate.

  In this invention, by separating the discharge electrode portion from the surface of the insulating substrate, the upper surface, the lower surface, and the opposite side surfaces of the pair of discharge electrodes can be used for discharge. Thereby, plasma can be generated effectively and the amount of ozone generated can be increased. In addition, foreign matters generated during discharge can be dropped into the cavity without remaining in the discharge gap. Thereby, generation | occurrence | production of the malfunction which a pair of discharge electrode short-circuits with a foreign material can be avoided.

  A discharge element according to the present invention includes an insulating substrate, a discharge electrode portion opposed via a discharge gap, and a pair of discharge electrodes each having a bonding portion bonded to the insulating substrate. A through hole provided in the plate is preferable.

  In the present invention, since the discharge gap is formed by a through-hole, a discharge gap with higher accuracy than the conventional discharge gap forming method can be realized.

  According to the present invention, it is not necessary to adjust the distance between the electrodes, and the generation cost of ozone can be suppressed.

FIG. 1A is a top view showing the structure of the discharge element according to the embodiment of the present invention. FIG. 1B is a cross-sectional view of the ozone generator shown in FIG. It is a flowchart which shows the manufacturing method of the discharge element which concerns on embodiment of this invention. It is a top view of the electrode plate. FIG. 4A is a cross-sectional view taken along the line BB of the electrode plate having a cavity formed therein. FIG. 4B is a cross-sectional view taken along line BB of the electrode plate having a discharge gap. FIG. 4C is a BB cross-sectional view of the electrode plate covered with the thermal oxide film. FIG. 5 is a top view of the electrode plate covered with the thermal oxide film shown in FIG. FIG. 6A is a cross-sectional view of an insulating substrate coated with frit glass. FIG. 6B is a CC cross-sectional view of the insulating substrate to which the electrode plate covered with the thermal oxide film is attached. FIG. 6C is a cross-sectional view taken along the line CC of the insulating substrate in which frit glass is baked and the electrode plate is bonded. FIG. 6D is a cross-sectional view taken along the line C-C of the electrode plate that has been half-cut. FIG. 7A is a CC cross-sectional view of an electrode plate on which metal electrodes are formed. FIG. 7B is a CC cross-sectional view of the discharge element that has been subjected to the full cut process.

  FIG. 1A is a top view showing the structure of the discharge element according to the embodiment of the present invention. FIG. 1B is a cross-sectional view of the ozone generator shown in FIG. 1, FIG. 2 to FIG. 7 show each part at a ratio different from the actual dimensional ratio in order to clarify the relationship between the parts.

  The discharge element 1 includes an insulating substrate 2 and a pair of discharge electrodes 3A and 3B. The discharge element 1 has a small size, for example, 2.0 mm × 2.5 mm × 900 μm.

  The insulating substrate 2 supports a pair of discharge electrodes 3A and 3B. The insulating substrate 2 is made of glass and has a thickness of 600 μm as an example. When glass is used as the insulating substrate 2, a material having a linear expansion coefficient close to that of silicon, which is a material of the discharge electrodes 3A and 3B, is preferable, such as Tempax Float (registered trademark). Further, the insulating substrate 2 may be formed of a material such as ceramics that is less likely to deteriorate when an AC high voltage is applied than a silicon thermal oxide film 4 that is an insulating film that covers the discharge electrodes 3A and 3B, as will be described later. Is possible.

  The discharge electrodes 3A and 3B are made of single crystal silicon and have a thickness of 300 μm as an example. The discharge electrodes 3A and 3B include joint portions 31A and 31B and discharge electrode portions 32A and 32B, respectively. The discharge electrodes 3 </ b> A and 3 </ b> B are joined to the insulating substrate 2 at joints 31 </ b> A and 31 </ b> B, respectively. The discharge electrode portions 32A and 32B are formed in a comb shape and face each other with the discharge gap 12 interposed therebetween. The discharge electrode portions 32A and 32B have a thickness of 30 μm. The interval of the discharge gap 12 is 20 μm. Further, the discharge electrode portions 32 </ b> A and 32 </ b> B are opposed to the insulating substrate 2 through the space (cavity) 11. As an example, the cavity 11 has a depth of 270 μm and a width of 1 mm.

  The discharge electrodes 3A and 3B are covered with a silicon thermal oxide film 4 which is an insulating film except for a part of the end portions. In the discharge electrodes 3A and 3B, metal electrodes 5A and 5B for voltage application are formed in the openings at the ends not covered with the silicon thermal oxide film 4. The metal electrodes 5A and 5B are made of Au, Pt, or Ti.

When ozone (O ₃ ) is generated in the discharge element 1, an external power source 7 is connected to the metal electrodes 5A and 5B formed on the discharge electrodes 3A and 3B as shown in FIG. Apply high voltage. When the AC high voltage applied from the external power supply 7 is gradually increased to reach the discharge start voltage, discharge is started on the surfaces of the discharge electrode 3A and the discharge electrode 3B in the discharge gap 12, and plasma 200 is generated. By this plasma 200, oxygen in the air is decomposed and combined to generate ozone. According to Paschen's law, the discharge start voltage is the lowest in the vicinity of 20 μm at atmospheric pressure. In the discharge element 1, since the interval between the discharge gaps 12 is set to 20 μm as described above, discharge can be started at 2 kVp-p or less to generate plasma.

  Next, the manufacturing method of the discharge element of this invention is demonstrated based on FIGS. FIG. 2 is a flowchart showing a method for manufacturing a discharge element according to an embodiment of the present invention. FIG. 3 is a top view of the electrode plate. FIG. 4A is a cross-sectional view taken along the line BB of the electrode plate having a cavity formed therein. FIG. 4B is a cross-sectional view taken along line BB of the electrode plate having a discharge gap. FIG. 4C is a BB cross-sectional view of the electrode plate covered with the thermal oxide film. FIG. 5 is a top view of the electrode plate covered with the thermal oxide film shown in FIG. FIG. 6A is a cross-sectional view of an insulating substrate coated with frit glass. FIG. 6B is a CC cross-sectional view of the insulating substrate to which the electrode plate covered with the thermal oxide film is attached. FIG. 6C is a cross-sectional view taken along the line CC of the insulating substrate in which frit glass is baked and the electrode plate is bonded. FIG. 6D is a cross-sectional view taken along the line C-C of the electrode plate that has been half-cut. FIG. 7A is a CC cross-sectional view of an electrode plate on which metal electrodes are formed. FIG. 7B is a CC cross-sectional view of the discharge element that has been subjected to the full cut process.

  In the present invention, the discharge electrode 3A and the discharge electrode 3B are prepared from the electrode plate 51. First, the electrode 3A and the discharge electrode 3B are partially connected to each other. The discharge gap 12 is provided in the plate body 51. Then, after the electrode plate 51 is bonded to the insulating substrate 2, the electrode plate 51 is divided together with the insulating substrate 2 so that the discharge electrode 3A and the discharge electrode 3B are separated. According to such a manufacturing method, the interval of the discharge gap 12 does not change and is always constant, so that adjustment of the electrode interval is not necessary.

  Hereafter, the manufacturing method of the discharge element of this invention is demonstrated concretely.

(1) Cavity Formation Step First, an electrode plate 51 as shown in FIG. 3 is prepared. The electrode plate 51 is made of single crystal silicon and has a thickness of 300 μm. The electrode plate 51 is sized so that m × n (m and n are natural numbers) cells 3 are obtained after the vertical and horizontal directions are divided. The cell 3 is separated into a discharge electrode 3A and a discharge electrode 3B in a process described later. Around each cell 3, margins 52T and 52Y that are cut during dicing are provided. The margin 52T is a margin in the vertical direction in FIG. 3, and is provided at each first interval. The margin 52Y is a margin in the horizontal direction in FIG. 3, and is provided at every second interval.

  As shown in FIG. 4A, cavities 11 that are a plurality of recesses are provided at regular intervals on one surface (lower surface in the drawing) 51U of the electrode plate 51 (S1). FIG. 4A shows an example in which m × n cavities 11 are provided on one surface 51U of the electrode plate 51 at regular intervals. The cavity 11 is formed on one surface 51U of the electrode plate 51 by dry etching using a photoresist as a mask. The depth of the cavity 11 is 270 μm as described above.

(2) Discharge gap forming step As shown in FIGS. 4B and 5, meander-like through holes are provided in the plurality of cavities 11 (S2). This meander-shaped through hole is the discharge gap 12. The discharge gap 12 is formed by dry etching from the other surface (upper surface in FIG. 4B) 51H of the electrode plate 51 using a photoresist as a mask. By forming the meander-shaped through hole in this manner, the discharge electrode 3A and the discharge electrode 3B have a comb shape. The interval between the comb-like portions of the discharge electrode 3A and the discharge electrode 3B is 20 μm. As shown in FIG. 5, after the discharge gap 12 is formed, in each cell 3 of the electrode plate 51, the discharge electrode 3 </ b> A and the discharge electrode 3 </ b> B are opposed to each other through the discharge gap 12. Further, the discharge electrode 3A and the discharge electrode 3B are partially connected to each other by two cutting edges 52Y. Further, in the adjacent cell 3, the discharge electrode 3B and the discharge electrode 3A are connected by a margin 52T.

(3) Thermal oxide film forming step After cleaning the electrode plate 51 provided with the plurality of discharge gaps 12, the surface thereof is thermally oxidized (S3). Thermal oxidation of the single crystal silicon that is the electrode plate 51 is performed by steam oxidation at a steam temperature of 1100 ° C. and a heat treatment time of 40 hours. As a result, the electrode plate 51 is covered with the silicon thermal oxide film 4 as shown in FIGS.

(4) Frit glass application process As shown to FIG. 6 (A), frit glass 2F is apply | coated to one surface of the glass-made insulating substrates 2G, and it pre-sinters (S4). As is well known, the frit glass is powdery glass, and in this embodiment, the frit glass is used as an adhesive for bonding the electrode plate 51 to the insulating substrate 2.

(5) Joining Step As shown in FIGS. 6A and 6B, an electrode substrate in which an insulating substrate 2G preliminarily sintered with frit glass 2F is coated with a silicon thermal oxide film 4 in step S3. One surface 51U of the body 51 is bonded in a vacuum chamber. Then, the frit glass 2F is sintered. Thereby, as shown in FIG. 6C, the electrode plate 51 covered with the silicon thermal oxide film 4 is bonded to the insulating substrate 2G, and the frit glass 2F is integrated with the insulating substrate 2G (S5). Hereinafter, the integrated frit glass 2F and the insulating substrate 2G are referred to as an insulating substrate 2.

(6) Opening Forming Step As shown in FIG. 6 (D), in the electrode plate 51, a width wider than the cutting margin 52T along the cutting margin 52T that is an intermediate portion of the cavity 11 adjacent to the left and right. Dicing (half-cut process) is performed. That is, the portion of the silicon thermal oxide film 4 where the metal electrode 5 is to be formed is removed to form a plurality (m + 1) of openings (recesses) 3H from which the electrode plate 51 is exposed (S6).

(7) Metal Electrode Forming Step As shown in FIG. 7A, in the electrode plate 51, vapor deposition using a metal mask in the opening 3H from which the silicon thermal oxide film 4 has been removed in the dicing (half cut) step. A metal electrode (either Au / Pt / Ti) 5 is formed by a method or the like (S7).

  The single crystal silicon used for the electrode plate 51 is n-type silicon having a resistivity of 0.1 Ωcm or less in order to reduce the contact resistance with the metal electrode 5.

(8) Dicing process (full cut)
As shown in FIG. 7B, dicing (full cut processing) is performed on the electrode plate 51 to divide it along a cutting margin 52T and a cutting margin 52Y (not shown), and a plurality (m × n). The discharge element 1 is generated (S8). As described above, by cutting the cutting margin 52Y, the discharge electrodes 3A and 3B facing each other through the discharge gap 12 are separated, and isolation between the electrodes can be ensured.

  By manufacturing the discharge element 1 by the manufacturing method as described above, the through hole formed by etching becomes the discharge gap 12, the interval of the discharge gap 12 does not change, and is always constant, and the interval adjustment of the electrodes can be adjusted. It is unnecessary. That is, in this embodiment, since a through-hole is provided in the single crystal silicon electrode plate and the through-hole is used as a discharge gap, the interval between the discharge electrodes is determined by the processing accuracy of the through-hole. This processing accuracy is much higher than the accuracy of adjusting the interval between the discharge electrodes in the conventional ozone generator. Therefore, variation in the gap of the discharge gap is suppressed.

  In addition, since the discharge gap 12 is formed using a semiconductor process, a minute gap can be formed with high accuracy, and discharge can be started at a low voltage to generate plasma.

  Further, in the present invention, the discharge electrodes 3A and 3B with the silicon thermal oxide film are subjected to temperature resistance after the step of coating the discharge electrode 3A and the discharge electrode 3B with the silicon thermal oxide film 4 at a high temperature. Affixed to the low insulating substrate 2G. Thereby, the silicon thermal oxide film 4 can be formed densely and without voids without adversely affecting the insulating substrate 2G. Thereby, the discharge element 1 having high reliability and excellent characteristics can be manufactured.

  Moreover, since the discharge element 1 has a simple configuration as described above and the manufacturing process is also simple, mass production is possible.

  In the present invention, after forming the cavity 11 in the electrode plate 51 as described above, the discharge gap 12 is formed in the cavity 11 to thereby form the thickness of the portion of the electrode plate 51 where the discharge gap 12 is formed. Therefore, the formation time of the discharge gap 12 can be shortened.

  In the discharge element 1, the discharge electrode portion 32 </ b> A of the discharge electrode 3 </ b> A and the discharge electrode portion 32 </ b> B of the discharge electrode 3 </ b> B that face each other via the discharge gap 12 are separated from the surface of the insulating substrate 2. ing. Thereby, since the upper surface, the lower surface, and the opposite side surfaces of the discharge electrode 3A and the discharge electrode 3B can be used for discharge, plasma can be generated effectively and the amount of ozone generated can be increased. Further, in the discharge element 1, in addition to the above structure, the width of the cavity 11 is larger than the width of the discharge gap 12 as described above. Thereby, since the foreign material generated at the time of discharge does not remain in the discharge gap 12 and falls into the cavity 11, it is possible to avoid the occurrence of a short circuit between the discharge electrode 3A and the discharge electrode 3B due to the foreign material.

  In the present invention, before the electrode plate 51 bonded to the insulating substrate 2 is divided, the openings 3H and the metal electrodes 5A and 5B are collectively formed for the plurality of discharge elements 1. As compared with the case where the electrode is formed after dividing, the discharge element can be manufactured more efficiently.

  In addition, by forming the metal electrodes 5A and 5B on the electrode plate 51, after the electrode plate 51 is divided, it becomes easy to apply an alternating high voltage to the discharge electrodes 3A and 3B, and plasma is efficiently generated. Can be generated.

  In addition to the method of using frit glass, the electrode plate 51 is bonded and bonded to the insulating substrate 2 by anodic bonding, bonding by direct bonding, bonding by an adhesive, and the like. Any method may be used as long as the positional deviation between the electrode 3A and the discharge electrode 3B does not occur.

DESCRIPTION OF SYMBOLS 1 ... Discharge element 2, 2G ... Insulating substrate 2F ... Frit glass 3 ... Cell 3A, 3B ... Discharge electrode 3H ... Opening 4 ... Silicon thermal oxide film 5A, 5B ... Metal electrode 7 ... External power supply 11 ... Cavity 12 ... Discharge Gap (through hole)
31A, 31B ... Joints 32A, 32B ... Discharge electrode part 51 ... Electrode plate 200 ... Plasma

Claims (6)

A pair of discharge electrodes opposed via a discharge gap;
An insulating substrate supporting the pair of discharge electrodes;
A method of manufacturing a discharge element comprising:
Forming a through-hole to be used as the discharge gap in the electrode plate, and forming the pair of discharge electrodes in a partially connected state; and
A bonding step of bonding one surface of the electrode plate provided with the through hole to an insulating substrate;
A dicing step of dividing the electrode plate bonded to the insulating substrate to generate a discharge element in which the pair of discharge electrodes are separated; and
A method for producing a discharge element, comprising: Before the gap forming step,
The manufacturing method of the discharge element of Claim 1 provided with the cavity formation process which provides a cavity in one surface of the electrode plate body. Between the gap forming step and the joining step,
The manufacturing method of the discharge element of Claim 1 or 2 provided with the film | membrane formation process which coat | covers the said plate for electrodes with a thermal oxide film. Between the joining step and the dicing step,
An opening forming step of forming a plurality of openings in which the electrode plate is exposed from the thermal oxide film between the discharge gaps of the electrode plate;
A metal electrode forming step of forming a metal electrode in the plurality of openings;
The manufacturing method of the discharge element in any one of Claims 1 thru | or 3 provided with these. An insulating substrate;
A pair of discharge electrodes each having a discharge electrode portion opposed via a discharge gap, and a bonding portion bonded to the insulating substrate;
With
The discharge element is characterized in that the discharge electrode portion is separated from the insulating substrate. An insulating substrate;
A pair of discharge electrodes each having a discharge electrode portion opposed via a discharge gap, and a bonding portion bonded to the insulating substrate;
With
The discharge element, wherein the discharge gap is a through hole provided in an electrode plate.

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