JP4181783B2 - Ozone gas concentration measurement method - Google Patents
Ozone gas concentration measurement method Download PDFInfo
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- JP4181783B2 JP4181783B2 JP2002062781A JP2002062781A JP4181783B2 JP 4181783 B2 JP4181783 B2 JP 4181783B2 JP 2002062781 A JP2002062781 A JP 2002062781A JP 2002062781 A JP2002062781 A JP 2002062781A JP 4181783 B2 JP4181783 B2 JP 4181783B2
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- ozone gas
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Description
【０００１】
【発明の属する技術分野】
本発明は、オゾンガス濃度の測定方法に関し、特に、発生したオゾンを濃縮して得られる高濃度オゾンガスの濃度測定方法に関する。
【０００２】
【従来の技術】
オゾンガスは強い酸化力を有しており、半導体製造分野等では、酸化膜形成等の用途が見込まれるが、従来、純酸素ガスを原料として高能力のオゾン発生器を使用しても、１０vol ％程度の濃度のオゾンガスしか生成できなかった。そこで、近年、オゾン発生器で発生したオゾンガスを濃縮し、高濃度のオゾンガスに形成する技術が種々提案されている。
【０００３】
しかし、酸化膜形成等の作業では、供給するオゾンガス濃度は形成される酸化膜の膜厚や性質に大きく影響することから、供給されるオゾンガス濃度を知ることは重要な要請となっている。
【０００４】
【発明が解決しようとする課題】
ところが、従来、濃縮された高濃度オゾンガスの濃度を測定するものは確立しておらず、実際に供給されるオゾンの濃度を正確に知ることはできなった。
【０００５】
本発明は、このような点に着目して、供給されるオゾンガス源に貯留されているオゾンガスの濃度を測定する方法を提供することを目的とする。
【０００６】
【課題を解決するための手段】
上述の目的を達成するために、請求項１に記載した発明は、オゾンガス源に貯留されているオゾンガスをその濃度を１２ vol ％以上の高濃度状態で分解容器内に１３ . ３ kPa 以下の圧力で封入し、封入されたオゾンガスを分解容器内で強制分解させることで封入オゾンガスの全量を瞬時に酸素へと分解させ、分解後の上昇圧力と上昇温度から封入オゾンガスの濃度を検知するように構成したものである。
【０００７】
請求項２に記載した発明は、封入されたオゾンガスを分解容器内で強制分解させる際に分解容器内に火花を発生させて強制着火するようにしたものである。
【０００８】
【発明の作用】
本発明は、分解容器内に大気圧未満の圧力で封入されたオゾンガスを強制分解させて、封入オゾンガスの全量を酸素に分解させ、分解後の上昇圧力と上昇温度から封入されたオゾンガスの濃度を知るようにしていることから、１００vol ％のオゾンが全量酸素ガスに分解すると体積が１.５倍、つまり圧力が１.５倍となることから、その圧力上昇率を知ることで、元のオゾンガス濃度を知ることができることになる。また、その際、検出した温度に基づき圧力を温度補正することでより正確なオゾンガス濃度を検出することができることになる。
【０００９】
【発明の実施の形態】
図は本発明方法を適用するオゾン濃度測定システムの一例を示すガス略流れ図である。
このオゾン濃度測定システムは、オゾンガス源から供給されるオゾンガスの濃度を検出するもので、空気分離装置や酸素ガス貯蔵容器等の酸素ガス源(１)から導出された酸素ガスをオゾン発生器(２)に通して発生させたオゾンガスを吸着式のオゾン濃縮装置(３)に導入して濃縮し、このオゾン濃縮装置(３)から取り出したオゾンガスを分解容器(４)内に導入後封止し、分解容器(４)内で導入されたオゾンガスに直流電気火花を発生させて、導入されたオゾンガスを瞬時に酸素に強制分解させ、分解操作前後での圧力差から導入されたオゾンガスの濃度を検出するものである。この場合、オゾン濃縮装置(３)がオゾンガス源となる。
【００１０】
図中符号(５)は直流電気火花を発生させる着火エネルギー付与回路、(６)は吸着式オゾン濃縮装置(３)にオゾンガスを吸着させる際に吸着されなかった酸素ガス等を導出する導出ライン、(７)は吸着式オゾン濃縮装置(３)からオゾンガスを離脱させる際に使用する減圧ライン、(８)は減圧ライン(７)に配置した吸引ポンプ、(10)は吸着式オゾン濃縮装置(３)の内圧を検出する圧力計、(11)は分解容器(４)の内圧を検出する圧力計、(12)は分解容器(４)の内部温度を検出する温度センサーである。
【００１１】
導入されたオゾンガスを強制分解させると、温度一定の定容下では、
２Ｏ3 →３Ｏ2
となることから、１００％オゾンガスの場合には、１.５倍の圧力上昇を伴なうことから、オゾンガスを導入した際の分解容器(４)内の圧力をＰ1、強制分解操作後の容器内圧力をＰ2とした場合、温度が一定であれば、その導入されたオゾンガス濃度(ｘvol％)は、
ｘ(vol％)＝{(Ｐ2−Ｐ1)／(１.５Ｐ1−Ｐ1)}×１００
で求めることができる。
【００１２】
なお、分解させるとその分解熱でガス温度が上昇することから、温度が落ち着いてから圧力測定することになるが、高圧封入したオゾンガスを分解させるとその温度上昇が大きく、冷却して元の温度まで低下するのに時間がかかることになる。このため、分解容器(４)にオゾンガスの圧力をできるだけ低圧にして封入する。
【００１３】
ちなみに、オゾン濃度が６０ vol％の場合、封入圧力が絶対圧で４kPa(３０Torr)であると、温度上昇は１〜２℃程度であるが、封入圧力が絶対圧で６６.５kPａ(５００Torr)であると、３０℃程度の温度上昇となる。したがって、封入圧力を絶対圧で１３.３kPa(１００Torr)程度以下にすることにより、温度上昇を６℃以下に抑えることができ、元の温度に戻すまでの冷却時間を短縮することができることになる。また、検出温度から分解後の圧力を補正することもできる。さらに、オゾン濃度が８０ vol％の場合には、２kPa(１５Torr)でも急激に分解反応することを確かめている。
【００１４】
上述のオゾン濃度測定システムでは、分解容器(４)内に付与する着火エネルギーとして、直流電気火花を使用したが、交流電気火花やニクロム線加熱等の電気エネルギーを使用しても良い。さらに、上述のオゾン濃度測定システムでは、発生させたオゾンガスを濃縮する装置としてオゾンを選択吸着する吸着剤を使用して吸着する吸着式オゾン濃縮装置を使用したが、液化による液化方式で濃縮するようにしても良い。さらに、このオゾン濃度測定方式は、測定するオゾンガスとしてオゾン発生器(２)で発生したオゾンガスや、オゾン貯蔵容器に貯蔵されているオゾンガスの濃度を測定することもできる。この場合、オゾン発生器(２)やオゾン貯蔵容器がオゾンガス源となる。
【００１５】
［実験例］
オゾン発生器(２)で発生させた５vol ％のオゾンガスを吸着式オゾン濃縮装置(３)に大気圧、−９０℃でオゾンガスを飽和吸着させ、その後、６.６５kPa(５０Torr)まで減圧して、オゾン濃縮操作を行った。その後、略６.６５kPa(Torr)を保ちながら−７０℃まで昇温させてオゾンガスを吸着剤から脱着させ、脱着した高濃度オゾンガスを分解容器(４)に約５.３２kPa(４０Torr)で回収し、密閉静置させた。ついで着火エネルギー付与回路(５)のコンデンサに蓄えた電荷を７kVに昇圧して放電させることで、分解容器(４)内に直流火花を発生させ、分解容器(４)内に回収したオゾンガスを強制着火させて、全量を酸素ガスへ分解させた。
【００１６】
その結果は以下のとおりであった。
【表１】
【発明の効果】
本発明では、測定対象となるオゾンガスを分解容器内に封入し、分解容器内に着火エネルギーを作用させて分解容器内に封入されているオゾンガスの全量を酸素ガスに瞬時に分解させ、分解後の圧力と封入圧力との圧力差から、導入されたオゾンガスの濃度を検出するように構成しているので、測定対象となっているオゾンガスの濃度を、効率よく正確に検出することができる。また、その際、検出した温度に基づき圧力を温度補正することでより正確なオゾンガスの濃度を検出することができることになる。
【００１８】
さらに、分解容器への封入圧力を大気圧未満の圧力にしているので、オゾンガスの分解後での上昇温度幅を小さくすることができ、分解容器が元の温度に戻る間での時間をより短時間にすることができ、濃度測定に要する作業時間を短時間にすることができる。
【図面の簡単な説明】
【図１】オゾン濃度測定システムの一例を示すガス略流れ図である。
【符号の説明】
４…分解容器。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for measuring ozone gas concentration, and more particularly, to a method for measuring the concentration of high-concentration ozone gas obtained by concentrating generated ozone.
[0002]
[Prior art]
Ozone gas has a strong oxidizing power. In the semiconductor manufacturing field, etc., it is expected to be used for oxide film formation. Conventionally, even if a high-capacity ozone generator is used as a raw material, pure oxygen gas is 10 vol%. Only ozone gas with a moderate concentration could be produced. Therefore, in recent years, various techniques for concentrating ozone gas generated by an ozone generator to form high-concentration ozone gas have been proposed.
[0003]
However, in operations such as oxide film formation, it is important to know the ozone gas concentration to be supplied because the ozone gas concentration to be supplied greatly affects the thickness and properties of the oxide film to be formed.
[0004]
[Problems to be solved by the invention]
However, there has been no established method for measuring the concentration of concentrated high-concentration ozone gas, and it has been impossible to accurately know the concentration of ozone actually supplied.
[0005]
This invention pays attention to such a point, and it aims at providing the method of measuring the density | concentration of the ozone gas stored in the ozone gas source supplied.
[0006]
[Means for Solving the Problems]
To achieve the above object, the present invention is 13 ozone gas reserved in the ozone gas source its concentration in the decomposition vessel at high concentration of more than 12 vol%. 3 kPa below the pressure according to
[0007]
According to the second aspect of the present invention, when the enclosed ozone gas is forcibly decomposed in the decomposition container, a spark is generated in the decomposition container to forcibly ignite .
[0008]
[Effects of the Invention]
The present invention forcibly decomposes ozone gas enclosed in a decomposition vessel at a pressure lower than atmospheric pressure, decomposes the entire amount of the enclosed ozone gas into oxygen, and determines the concentration of the ozone gas enclosed from the increased pressure and temperature after decomposition. As we know, when 100 vol% of ozone is decomposed into oxygen gas, the volume is 1.5 times, that is, the pressure is 1.5 times. By knowing the pressure increase rate, the original ozone gas You will know the concentration. At that time, more accurate ozone gas concentration can be detected by correcting the pressure based on the detected temperature.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The figure is a schematic gas flow diagram showing an example of an ozone concentration measuring system to which the method of the present invention is applied.
This ozone concentration measuring system detects the concentration of ozone gas supplied from an ozone gas source. Oxygen gas derived from an oxygen gas source (1) such as an air separation device or an oxygen gas storage container is converted into an ozone generator (2 ) Is introduced into the adsorption-type ozone concentrator (3) and concentrated, and the ozone gas taken out from the ozone concentrator (3) is introduced into the decomposition vessel (4) and sealed. A direct current spark is generated in the ozone gas introduced in the decomposition vessel (4), the introduced ozone gas is instantaneously forcedly decomposed into oxygen, and the concentration of the introduced ozone gas is detected from the pressure difference before and after the decomposition operation. Is. In this case, the ozone concentrator (3) serves as an ozone gas source.
[0010]
In the figure, reference numeral (5) is an ignition energy applying circuit for generating a DC electric spark, and (6) is a lead-out line for deriving oxygen gas that has not been adsorbed when adsorbing ozone gas to the adsorption ozone concentrator (3). (7) is a decompression line used to desorb ozone gas from the adsorption ozone concentrator (3), (8) is a suction pump disposed in the decompression line (7), and (10) is an adsorption ozone concentrator (3 ) Is a pressure gauge for detecting the internal pressure of the decomposition vessel (4), and (12) is a temperature sensor for detecting the internal temperature of the decomposition vessel (4).
[0011]
When the introduced ozone gas is forcibly decomposed, under a constant volume at a constant temperature,
2O 3 → 3O 2
Therefore, in the case of 100% ozone gas, the pressure rises by a factor of 1.5. Therefore, when the ozone gas is introduced, the pressure in the decomposition vessel (4) is P 1 , after the forced decomposition operation. If the container pressure was P 2, when the temperature is constant, the introduced ozone gas concentration (xVOL%) is
x (vol%) = {(P 2 −P 1 ) / (1.5P 1 −P 1 )} × 100
Can be obtained.
[0012]
Since the gas temperature rises due to the heat of decomposition when decomposed, the pressure will be measured after the temperature has settled down.However, when ozone gas enclosed in high pressure is decomposed, the temperature rises greatly, and the original temperature is reduced by cooling. It will take time to decrease. For this reason, the ozone gas is sealed in the decomposition vessel (4) at as low a pressure as possible.
[0013]
By the way, when the ozone concentration is 60 vol%, if the enclosed pressure is 4 kPa (30 Torr) in absolute pressure, the temperature rise is about 1 to 2 ° C, but the enclosed pressure is 66.5 kPa (500 Torr) in absolute pressure. If it exists, the temperature rises by about 30 ° C. Therefore, by setting the sealed pressure to 13.3 kPa (100 Torr) or less in absolute pressure, the temperature rise can be suppressed to 6 ° C. or less, and the cooling time to return to the original temperature can be shortened. . Moreover, the pressure after decomposition | disassembly can also be correct | amended from detected temperature. Furthermore, when the ozone concentration is 80 vol%, it has been confirmed that a rapid decomposition reaction occurs even at 2 kPa (15 Torr).
[0014]
In the above ozone concentration measurement system, a direct current electric spark is used as the ignition energy applied to the decomposition vessel (4). However, an electric energy such as an alternating current spark or nichrome wire heating may be used. Furthermore, in the above-mentioned ozone concentration measurement system, an adsorption type ozone concentrating device that adsorbs using an adsorbent that selectively adsorbs ozone is used as a device for concentrating the generated ozone gas, but it is concentrated by a liquefaction method by liquefaction. Anyway. Furthermore, this ozone concentration measurement method can also measure the concentration of ozone gas generated by the ozone generator (2) as the ozone gas to be measured or the concentration of ozone gas stored in the ozone storage container. In this case, the ozone generator (2) and the ozone storage container serve as the ozone gas source.
[0015]
[Experimental example]
5 vol% ozone gas generated by the ozone generator (2) is adsorbed to the adsorption-type ozone concentrator (3) at atmospheric pressure and −90 ° C. by saturated adsorption, and then reduced to 6.65 kPa (50 Torr), Ozone concentration operation was performed. Thereafter, the temperature is raised to −70 ° C. while maintaining approximately 6.65 kPa (Torr), the ozone gas is desorbed from the adsorbent, and the desorbed high-concentration ozone gas is collected in the decomposition vessel (4) at about 5.32 kPa (40 Torr). And allowed to stand still. Next, by boosting the charge stored in the capacitor of the ignition energy application circuit (5) to 7 kV and discharging it, a direct current spark is generated in the decomposition vessel (4), and the ozone gas collected in the decomposition vessel (4) is forced. The whole amount was decomposed into oxygen gas by ignition.
[0016]
The results were as follows.
[Table 1]
【The invention's effect】
In the present invention, the ozone gas to be measured is enclosed in a decomposition container, and the ignition energy is allowed to act in the decomposition container to instantaneously decompose the total amount of ozone gas enclosed in the decomposition container into oxygen gas. Since the concentration of the introduced ozone gas is detected from the pressure difference between the pressure and the sealed pressure, the concentration of the ozone gas to be measured can be detected efficiently and accurately. At that time, the temperature of the pressure is corrected based on the detected temperature, whereby a more accurate ozone gas concentration can be detected.
[0018]
Furthermore, since the pressure enclosed in the decomposition vessel is set to a pressure lower than atmospheric pressure, the temperature rise after ozone gas decomposition can be reduced, and the time required for the decomposition vessel to return to the original temperature can be shortened. The working time required for concentration measurement can be shortened.
[Brief description of the drawings]
FIG. 1 is a schematic gas flow diagram showing an example of an ozone concentration measurement system.
[Explanation of symbols]
4 ... Decomposition container.
Claims (2)
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002062781A JP4181783B2 (en) | 2002-03-08 | 2002-03-08 | Ozone gas concentration measurement method |
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|---|---|---|---|
| JP2002062781A JP4181783B2 (en) | 2002-03-08 | 2002-03-08 | Ozone gas concentration measurement method |
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| JP2003262627A JP2003262627A (en) | 2003-09-19 |
| JP4181783B2 true JP4181783B2 (en) | 2008-11-19 |
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| JP4609206B2 (en) * | 2005-07-04 | 2011-01-12 | 住友化学株式会社 | Steam self-decomposition propagation evaluation apparatus and evaluation method |
| JP5184392B2 (en) * | 2008-01-23 | 2013-04-17 | 大陽日酸株式会社 | Indirect measurement method of ozone concentration |
| JP5272516B2 (en) * | 2008-05-23 | 2013-08-28 | 株式会社明電舎 | Process control method and process control system |
| JP5239053B2 (en) * | 2008-05-23 | 2013-07-17 | 株式会社明電舎 | Method and apparatus for measuring ozone concentration |
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