JP4036618B2

JP4036618B2 - Method and apparatus for measuring mixed gas

Info

Publication number: JP4036618B2
Application number: JP2001030589A
Authority: JP
Inventors: 秀彦野中; 明黒河; 哲也西口
Original assignee: Meidensha Corp; National Institute of Advanced Industrial Science and Technology AIST
Current assignee: Meidensha Corp; National Institute of Advanced Industrial Science and Technology AIST
Priority date: 2001-02-07
Filing date: 2001-02-07
Publication date: 2008-01-23
Anticipated expiration: 2021-02-07
Also published as: JP2002236083A

Description

【０００１】
【発明の属する技術分野】
本発明は、任意の気体からなる混合気体の混合比、さらにそれぞれの絶対量を測定する方法および装置に関する。
【０００２】
【従来の技術】
従来、２種類以上の気体からなる混合気体の混合比を求めるに際して、例えば、混合気体をイオン化して質量分離し、おのおののイオンの生成数を測定する方法あるいは適当な光源を用いて混合ガスによる吸収スペクトルを測定する方法などが知られている。
【０００３】
前者の代表例として四重極質量分析計がある。この方法では、四重極部に印加する電圧を固定、変化させることにより、分子の質量数に応じたスペクトルが得られ、一回の測定で全ての質量成分を検知できる。
【０００４】
【発明が解決しようとする課題】
このような混合比の測定に際して一般に用いられている測定方法は、気体分子の物理化学的特性を用いた間接的な方法で、圧力比という気体の分子数を直接反映した物理量を測定する方法ではなかった。
【０００５】
そのため、例えば上記のようにイオン化を用いて測定する方法では、気体分子の解離が避けられず、生成した気体分子のイオンの数と該気体分子数が一致しないことがある。
【０００６】
例えば、オゾン分子などが含まれる混合気体で見られる。また、一種類の気体に対して複数の質量数に信号が割れて現れたり（クラッキングパターン、例えばメタンでは質量数１２，１３，１４，１５，１６，１７に信号が現れる）、ガス種により感度が異なる、質量数が同じ気体は分離が難しい（例えば窒素と一酸化炭素）等によりガス組成を定量的に導き出すのは多くの場合困難である。
【０００７】
一方吸収スペクトルを測定した場合、用いた波長領域で全ての気体の吸収係数が有限でない限り、複数の気体の分子数比を定量的に精度良く求めることはできない。
【０００８】
本発明の目的は、上記の課題を解決した混合気体の測定方法およびその測定装置を提供することにある。
【０００９】
【課題を解決するための手段】
本発明は、混合気体に含まれるおのおのの気体の凝固点、沸点、およびそれらの間の温度における蒸気圧の概算値が既知である場合に、混合気体を全て凝縮（混合気体に含まれる全てのガスを蒸気圧が十分に低い固体状態に固化または蒸気圧が十分に低い液体状態に液化）し、その後に温度を適当な速度で上昇させることで蒸気圧温度が異なる気体毎に気化させ、このときの容器内の圧力変化から混合気体の絶対量さらには混合比を求めるようにしたものである。
【００１０】
また、本発明は、混合気体のうち凝縮温度が最低の気体を除く全ての気体を凝縮し、凝縮温度が最低の気体については混合気体の導入時の圧力上昇と容器体積との積により、または圧力と排気速度との積によりその絶対量を求め、他の気体については凝縮後に温度を上昇させることで蒸気圧温度が異なる気体毎に気化させ、このときの容器内の圧力変化から混合気体の絶対量さらには混合比を求めるようにしたものである。
【００１１】
したがって、本発明は、以下の測定方法および測定装置を特徴とする。
【００１２】
（方法の発明）
（１）蒸気圧特性が互いに異なる気体が混合した混合気体の各気体の絶対量を測定する方法であって、
予め真空に排気された容器または不活性ガスを導入した容器内に前記混合気体を導入し、容器内に導入された混合気体を冷却して凝縮させ、凝縮した液体または固体を徐々に昇温させて各気体を個別に気化させ、容器の体積を比例定数とし、各気体が個別に気化したときの容器内の圧力変化分の積によって各々の気体の絶対量を求めることを特徴とする。
【００１３】
（２）蒸気圧特性が互いに異なる気体が混合した混合気体の各気体の絶対量を測定する方法であって、
予め真空に排気された容器または不活性ガスを導入した容器内に前記混合気体を導入し、容器内に導入された混合気体のうち凝縮温度が最低の気体を除く全ての気体を冷却して凝縮させ、凝縮温度が最低の気体については混合気体導入時の圧力上昇と容器体積との積によりその絶対量を求め、他の気体については凝縮した液体または固体を徐々に昇温させて各気体を個別に気化させ、容器の体積を比例定数とし、各気体が個別に気化したときの容器内の圧力変化分の積によって各々の気体の絶対量を求めることを特徴とする。
【００１４】
（３）蒸気圧特性が互いに異なる気体が混合した混合気体の各気体の絶対量を測定する方法であって、
一定の排気速度で排気される容器内に前記混合気体を導入し、容器内に導入された混合気体を冷却して凝縮させ、凝縮した液体または固体を徐々に昇温させて各気体を個別に気化させ、前記排気速度を比例定数とし、各気体が個別に気化し始めたときから気化終了までの時間における容器内の圧力変化の積分によって各々の気体の絶対量を求めることを特徴とする。
【００１５】
（４）蒸気圧特性が互いに異なる気体が混合した混合気体の各気体の絶対量を測定する方法であって、
一定の排気速度で排気される容器内に前記混合気体を導入し、容器内に導入された混合気体のうち凝縮温度が最低の気体を除く全ての気体を冷却して凝縮させ、凝縮温度が最低の気体については混合気体導入時の圧力上昇と容器体積との積によりその絶対量を求め、他の気体については凝縮した液体または固体を徐々に昇温させて各気体を個別に気化させ、前記排気速度を比例定数とし、各気体が個別に気化し始めたときから気化終了までの時間における容器内の圧力変化の積分によって各々の気体の絶対量を求めることを特徴とする。
【００１６】
（５）上記の（１）〜（４）のいずれかに記載の混合気体の測定方法により各気体の絶対量を測定し、測定した各気体の絶対量の比から、混合気体の混合比を求めることを特徴とする。
【００１７】
（装置の発明）
（６）蒸気圧特性が互いに異なる気体が混合した混合気体の各気体の絶対量を測定する装置であって、
予め真空に排気された容器または不活性ガスを導入した容器内に前記混合気体を導入する手段と、容器内に導入された混合気体を冷却して凝縮させ、凝縮した液体または固体を徐々に昇温させて各気体を個別に気化させる温度調節手段と、容器内の圧力を測定する圧力計と、容器の体積を比例定数とし、各気体が個別に気化したときの容器内の圧力変化分の積によって各々の気体の絶対量を求める演算手段とを備えたことを特徴とする。
【００１８】
（７）蒸気圧特性が互いに異なる気体が混合した混合気体の各気体の絶対量を測定する装置であって、
予め真空に排気された容器または不活性ガスを導入した容器内に前記混合気体を導入する手段と、容器内に導入された混合気体のうち凝縮温度が最低の気体を除く全ての気体を冷却して凝縮させ、凝縮した液体または固体を徐々に昇温させて各気体を個別に気化させる温度調節手段と、容器内の圧力を測定する圧力計と、凝縮温度が最低の気体については混合気体導入時の圧力上昇と容器体積との積によりその絶対量を求め、他の気体については容器の体積を比例定数とし、各気体が個別に気化したときの容器内の圧力変化分の積によって各々の気体の絶対量を求める演算手段とを備えたことを特徴とする。
【００１９】
（８）蒸気圧特性が互いに異なる気体が混合した混合気体の各気体の絶対量を測定する装置であって、
容器内の気体を一定の排気速度で排気する真空ポンプと、容器内に前記混合気体を導入する手段と、容器内に導入された混合気体を冷却して凝縮させ、凝縮した液体または固体を徐々に昇温させて各気体を個別に気化させる温度調節手段と、容器内の圧力を測定する圧力計と、前記排気速度を比例定数とし、各気体が個別に気化し始めたときから気化終了までの時間におけるた容器内の圧力変化の積分によって各々の気体の絶対量を求める演算手段とを備えたことを特徴とする。
【００２０】
（９）蒸気圧特性が互いに異なる気体が混合した混合気体の各気体の絶対量を測定する装置であって、
容器内の気体を一定の排気速度で排気する真空ポンプと、容器内に前記混合気体を導入する手段と、容器内に導入された混合気体のうち凝縮温度が最低の気体を除く全ての気体を冷却して凝縮させ、凝縮した液体または固体を徐々に昇温させて各気体を個別に気化させる温度調節手段と、容器内の圧力を測定する圧力計と、凝縮温度が最低の気体については混合気体導入時の圧力と排気速度との積によりその絶対量を求め、他の気体については前記排気速度を比例定数とし、各気体が個別に気化し始めたときから気化終了までの時間におけるた容器内の圧力変化の積分によって各々の気体の絶対量を求める演算手段とを備えたことを特徴とする。
【００２１】
（１０）上記の（６）〜（９）のいずれかに記載の混合気体の測定装置により各気体の絶対量を測定し、測定した各気体の絶対量の比から、混合気体の混合比を求める演算手段を備えたことを特徴とする。
【００２２】
なお、前記凝縮した液体または固体の昇温は、各気体が個別に気化するのに十分な時間で昇温させる方法または装置とするのが好ましい。
【００２３】
また、前記混合気体の凝縮は、容器内のガス導入口近傍に熱伝導のよいターゲットを配置し、これを例えば冷凍機もしくは液体ヘリウム等の冷却手段で冷却することにより行うことができる。
【００２４】
また、ターゲットとしては、例えば銅などを用いることが好ましいが、室温の混合ガスが導入されてきたときにターゲットに温度上昇がなく、冷凍した温度と同じ温度に保たれる程度の冷凍手段との熱接触を保つことのできる熱伝導性があれば種々の材質のものを用いることができ、その配置も前記条件を満たしていれば導入口近傍に限るものではない。
【００２５】
また、ターゲットの形状としては、大きな表面積を確保するために、例えば円筒形とするなど、種々の形状を採用することができる。
【００２６】
【発明の実施の形態】
（実施形態１）
図１は、本発明の実施形態を示す測定装置の構成図である。この測定装置は、閉じた容器１内に混合気体を凝縮するためのターゲット２を設ける。このターゲット２は、冷却手段としての２段式冷凍機（または液体ヘリウムライン）３による冷却および昇温手段としてのヒータ４による昇温を可能にし、これら冷凍機３とヒータ４によってターゲットの温度調節手段を構成する。
【００２７】
ターゲット２は、表面積の大きい面を持つ形状（例えば円筒）にされ、また熱伝導のよい材質（例えば銅）で形成されて容器内のガス導入口近傍に配置される。測定対象となる混合気体（混合ガス）は、ターゲット２の表面を経て容器１内に導入されることで導入された混合気体のすべてが凝縮されることによりトラップされるようターゲット２の温度調整がされている。さらに、容器１内の圧力は適当な圧力計（例えばバラトロンあるいは水晶ゲージ）５によって常に計測可能にされる。
【００２８】
以上の装置による混合気体の混合比とおのおのの気体の絶対量測定には、まず、容器１内は不活性ガスで満たし、例えば適当な圧力にしたヘリウムガスで満たしておく（例えば０．１気圧）。このとき、ターゲット２は混合気体を凝縮できる温度４Ｋ程度に調節しておく。
【００２９】
なお、容器１内はヘリウムガスに代えて真空とすることでもよい。また、容器１の大きさは、混合ガスの総量を導入した時の最終的な到達圧力を見積もり、安全性および真空計の測定範囲から決定する。すなわち、多量に混合ガスを導入する場合、あるいは高圧側での圧力測定が困難な場合、あるいは混合ガスのうち高圧で満たすと危険な場合は容器１を大きくする。逆に、上記以外の場合で絶対量測定の感度を上げたい場合には容器１を小さくする。
【００３０】
次に、混合気体は配管を経由して容器１内のターゲット２面の近傍まで導入する。この導入により、冷凍機３（または液体ヘリウムライン）によりヘリウム以外の全てのガスをターゲット２上に凝縮（混合気体に含まれる全てのガスを蒸気圧が十分に低い固体状態に固化または蒸気圧が十分に低い液体状態に液化）させる。
【００３１】
その後、ヒータ４の運転によって、一定の割合（Ｋ／ｍｉｎ）でターゲット２の温度を上昇させる。ターゲット２の温度上昇（時間の経過）と共に、容器１内では図２のように初期圧力Ｐ０からの圧力上昇が見られる。図２では、混同気体の成分間で反応が起こらない場合を示し、圧力は存在気体の蒸気圧曲線に一致するはずであり、ある特定の気体Ａが完全に気化したときは圧力Ｐ１で圧力上昇が止まり、さらに昇温させると気体Ｂが気化を始め、その蒸気圧曲線に一致して圧力上昇し、圧力Ｐ２で圧力上昇が止まる。
【００３２】
このとき、到達圧力と初期圧力の差に容器の体積を掛けることで、下記の演算により気体の絶対量を求めることができる。さらに、これら絶対量から混合比を求めることができる。式中のＶは容器１の体積である。
【００３３】
【数１】
気体Ａの絶対量＝（Ｐ１−Ｐ０）×Ｖ
気体Ｂの絶対量＝（Ｐ２−Ｐ１）×Ｖ
混合比＝Ａ／Ｂ
なお、混合気体を凝縮させるのに、冷凍機もしくは液体ヘリウム等の冷却手段で冷却しておくターゲットとしては、例えば銅などを用いることが好ましいが、室温の混合ガスが導入されてきたときにターゲットに温度上昇がなく、冷凍した温度と同じ温度に保たれる程度の冷凍手段との熱接触を保つことのできる熱伝導性があれば種々の材質のものを用いることができ、その配置も前記条件を満たしていれば導入口近傍に限るものではない。また、ターゲットの形状としては、大きな表面積を確保するために、例えば円筒形とするなど、種々の形状を採用することができる。
【００３４】
また、凝縮した液体または固体の昇温は、各気体が個別に気化するのに十分な時間で昇温させるのが好ましい。
【００３５】
（実施形態２）
導入ガスが三種類以上の気体からなりその間で反応性が高い場合、あるいは導入ガスの中で圧力が高くなると爆発性を持つような気体を含んでいる場合は以下の方法で完全にそれぞれの絶対量を求めることができる。
【００３６】
この測定装置を図３に示す。同図が図１と異なる部分は、容器１には真空ポンプ６を設け、測定中には容器内を真空ポンプ６で常に排気しておく点にある。
【００３７】
以上の構成において、ターゲット２の温度を上げていくとそれぞれの気体の蒸気庄に対応する圧力Ｐの上昇の山が確認でき、それぞれの圧力上昇の山を時間積分し、それにポンプの実効排気速度Ｓ（１／時間）を掛けることにより各気体量を求めることができる。
【００３８】
図４を参照して、オゾンと酸素の混合ガスの場合の絶対量の求め方を説明する。オゾンと酸素の蒸気圧曲線は既知であり、融点はオゾンが８０Ｋ、酸素が５５Ｋ、沸点はオゾンが１６１Ｋ、酸素が９０Ｋである。図４は、この混合気体の凝縮温度を３０Ｋ、排気速度Ｓは２００リットル／秒としてターゲット温度を上昇させた場合の圧力Ｐの変化をイオンゲージで測定した結果である。
【００３９】
このときの酸素の絶対量測定は、下記に演算式を示すように、酸素が気化し始める温度（ターゲットが３０Ｋ）の時刻ｔ１から、酸素の気化が終了する温度（ターゲットが５０Ｋ）の時刻ｔ２までの圧力Ｐをそのときの排気速度Ｓを定数として積分することで求めることができる。同様に、オゾンの絶対量測定には、それが気化し始める時刻ｔ３から気化終了時刻ｔ４までの圧力Ｐの積分で求めることができる。
【００４０】
【数２】

【００４１】
本実施形態による測定方法および装置によれば、蒸気圧の高い成分から順番に圧力変化を計測しつつ排気（容器から排除）していくため、気体間で反応性が高い場合、ガス構成が複雑な場合などには実施形態１の方法に比べて優れる。
【００４２】
なお、実施形態１、２で説明したように、全てのガスをトラップできる温度に冷却することが好ましいが、トラップされる温度が最低のガスはトラップしなくても、排気していない場合にはガスを導入しているときの圧力上昇と容器体積の積により、排気している場合には導入の際の圧力と排気速度の積により、その絶対量を求めることができるので、測定対象となるガスのトラップ温度を考慮し、必要に応じて冷凍機等の冷却手段に要求される能力を下げることも可能である。
【００４３】
以上のように、本発明によれば、任意の気体からなる混合気体の各気体の絶対量および混合比を測定することが可能であり、特に反応性の高いガス、例えばオゾン、半導体酸窒化用に用いられるＮ_XＯ_YとＮＯ_X、例えばＮＯ₂とＮＯとの混合ガス、半導体エッチング用の塩素系ガスと塩素等の反応性の高いガスについては、一度凝縮することで安全に測定を行うことができる。
【００４４】
【発明の効果】
以上のとおり、本発明によれば、混合気体を全て凝縮し、その後に温度を適当な速度で上昇させることで蒸気圧温度が異なる気体毎に気化させ、このときの容器内の圧力変化から混合気体の混合比および絶対量を求めるようにしたため、任意の混合気体の混合比および絶対量を測定できる。
【００４５】
また、凝縮温度が最低のガスを除く全てのガスを凝縮とその後の気化による測定をし、凝縮温度が最低のガスについてはそのときの圧力上昇と容器体積の積や、圧力と排気速度の積によりその絶対量を求めるようにすれば、冷凍機等の冷却手段に要求される能力を下げることができる。
【００４６】
また、圧力計はダイナミックレンジが広いため（イオンゲージの場合５桁以上）混合比が桁で異なる場合でも正確に絶対量を求めることができる。さらに、気体状態のままでは不安定なとき、あるいは反応性が高いときでも、凝縮状態にすることにより安定状態にできる。また、混合気体のうち一部の成分が未知であるときでも、既知の気体の蒸気圧曲線を分離することにより、残りのガス種の決定および絶対量の決定が可能になる。
【図面の簡単な説明】
【図１】本発明の実施形態１を示す装置構成図。
【図２】混合気体間で反応がない場合の温度−圧力測定例。
【図３】本発明の実施形態２を示す装置構成図。
【図４】実施形態２における温度−圧力測定例。
【符号の説明】
１…容器
２…ターゲット
３…冷凍機
４…昇温用ヒータ
５…圧力計
６…真空ポンプ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for measuring a mixing ratio of a mixed gas composed of an arbitrary gas, and an absolute amount of each.
[0002]
[Prior art]
Conventionally, when obtaining the mixture ratio of a mixture of two or more gases, for example, the mixture gas is ionized and mass-separated, and the number of ions produced is measured or a suitable light source is used. A method for measuring an absorption spectrum is known.
[0003]
A typical example of the former is a quadrupole mass spectrometer. In this method, by fixing and changing the voltage applied to the quadrupole part, a spectrum corresponding to the mass number of the molecule can be obtained, and all mass components can be detected by a single measurement.
[0004]
[Problems to be solved by the invention]
The measurement method generally used for measuring the mixing ratio is an indirect method using the physicochemical characteristics of gas molecules, and is a method of measuring a physical quantity that directly reflects the number of gas molecules called a pressure ratio. There wasn't.
[0005]
For this reason, for example, in the method of measurement using ionization as described above, dissociation of gas molecules is unavoidable, and the number of ions of the generated gas molecules may not match the number of gas molecules.
[0006]
For example, it is found in a mixed gas containing ozone molecules. In addition, a signal appears to be broken at a plurality of mass numbers for one kind of gas (a signal appears at a cracking pattern, for example, mass numbers 12, 13, 14, 15, 16, and 17 in methane), or sensitivity depends on the gas type. However, in many cases, it is difficult to quantitatively derive the gas composition due to difficulty in separation (for example, nitrogen and carbon monoxide).
[0007]
On the other hand, when an absorption spectrum is measured, the molecular ratio of a plurality of gases cannot be determined quantitatively and accurately unless the absorption coefficients of all gases are finite in the used wavelength region.
[0008]
An object of the present invention is to provide a mixed gas measuring method and a measuring apparatus for solving the above problems.
[0009]
[Means for Solving the Problems]
The present invention condenses all of the mixed gas (all gases contained in the mixed gas) when the estimated freezing point, boiling point, and vapor pressure at the temperature between them are known. Solidify into a solid state with a sufficiently low vapor pressure or liquefy into a liquid state with a sufficiently low vapor pressure), and then raise the temperature at an appropriate rate to vaporize each gas with a different vapor pressure temperature. The absolute amount of the mixed gas and further the mixing ratio are obtained from the pressure change in the container.
[0010]
Further, the present invention condenses all gases except for the gas having the lowest condensation temperature among the mixed gases, and for the gas having the lowest condensation temperature, the product of the pressure increase at the time of introduction of the mixed gas and the container volume, or The absolute amount is obtained from the product of the pressure and the exhaust speed, and the other gases are vaporized for each gas having a different vapor pressure temperature by increasing the temperature after condensation. The absolute amount and the mixing ratio are obtained.
[0011]
Therefore, the present invention is characterized by the following measuring method and measuring apparatus.
[0012]
(Invention of method)
(1) A method for measuring an absolute amount of each gas of a mixed gas in which gases having different vapor pressure characteristics are mixed,
The mixed gas is introduced into a container that has been evacuated in advance or into which an inert gas has been introduced, the mixed gas introduced into the container is cooled and condensed, and the temperature of the condensed liquid or solid is gradually increased. Each gas is vaporized individually, the volume of the container is set as a proportional constant, and the absolute amount of each gas is obtained by the product of the pressure change in the container when each gas is vaporized individually.
[0013]
(2) A method for measuring an absolute amount of each gas of a mixed gas in which gases having different vapor pressure characteristics are mixed,
The mixed gas is introduced into a container that has been evacuated in advance or into which an inert gas has been introduced, and all of the mixed gas introduced into the container is cooled and condensed except for the gas having the lowest condensation temperature. For the gas with the lowest condensation temperature, obtain the absolute amount by the product of the pressure rise at the time of introduction of the mixed gas and the volume of the container, and for other gases, gradually raise the temperature of the condensed liquid or solid to each gas. Vaporization is performed individually, the volume of the container is set as a proportional constant, and the absolute amount of each gas is obtained by the product of the pressure change in the container when each gas is vaporized individually.
[0014]
(3) A method of measuring the absolute amount of each gas of a mixed gas in which gases having different vapor pressure characteristics are mixed,
The mixed gas is introduced into a container that is evacuated at a constant pumping speed, the mixed gas introduced into the container is cooled and condensed, and the temperature of the condensed liquid or solid is gradually raised to individually supply each gas. Vaporization is performed, the exhaust velocity is set as a proportional constant, and the absolute amount of each gas is obtained by integrating the pressure change in the container in the time from the start of vaporization of each gas to the end of vaporization.
[0015]
(4) A method for measuring an absolute amount of each gas of a mixed gas in which gases having different vapor pressure characteristics are mixed,
The mixed gas is introduced into a container that is evacuated at a constant pumping speed, and all of the mixed gas introduced into the container is cooled and condensed except for the gas having the lowest condensation temperature. For the other gases, the absolute amount is determined by the product of the pressure increase and the container volume when the mixed gas is introduced, and for other gases, the condensed liquid or solid is gradually heated to vaporize each gas individually, The exhaust velocity is set as a proportional constant, and the absolute amount of each gas is obtained by integrating the pressure change in the container in the time from the start of vaporization of each gas to the end of vaporization.
[0016]
(5) The absolute amount of each gas is measured by the method for measuring a mixed gas according to any one of ( 1) to (4 ) above, and the mixture ratio of the mixed gas is determined from the ratio of the measured absolute amount of each gas. It is characterized by seeking.
[0017]
(Invention of the device)
(6) An apparatus for measuring the absolute amount of each gas of a mixed gas in which gases having different vapor pressure characteristics are mixed,
Means for introducing the mixed gas into a container that has been evacuated in advance or a container into which an inert gas has been introduced, and the mixed gas introduced into the container is cooled and condensed to gradually raise the condensed liquid or solid. The temperature control means that vaporizes each gas individually by heating, the pressure gauge that measures the pressure in the container, and the volume of the container as a proportional constant, the amount of pressure change in the container when each gas vaporizes individually An arithmetic means for obtaining an absolute amount of each gas by a product is provided.
[0018]
(7) An apparatus for measuring the absolute amount of each gas of a mixed gas in which gases having different vapor pressure characteristics are mixed,
The means for introducing the mixed gas into a container previously evacuated to a vacuum or a container into which an inert gas has been introduced, and all the gases other than the gas having the lowest condensation temperature among the mixed gas introduced into the container are cooled. Condensate the liquid or solid that has been condensed and gradually raise the temperature to vaporize each gas individually, a pressure gauge to measure the pressure in the container, and introduce a mixed gas for the gas with the lowest condensation temperature The absolute amount is obtained from the product of the rise in pressure and the volume of the container.For other gases, the volume of the container is set as a proportional constant, and the product of the pressure change in the container when each gas is vaporized individually. And an arithmetic means for obtaining an absolute amount of gas.
[0019]
(8) An apparatus for measuring the absolute amount of each gas of a mixed gas in which gases having different vapor pressure characteristics are mixed,
A vacuum pump for exhausting the gas in the container at a constant exhaust speed, means for introducing the mixed gas into the container, cooling and condensing the mixed gas introduced into the container, and gradually condensing the condensed liquid or solid The temperature control means for vaporizing each gas individually by raising the temperature to the pressure, the pressure gauge for measuring the pressure in the container, and the exhaust speed as a proportional constant, from the time when each gas starts to vaporize until the end of vaporization And a calculating means for obtaining the absolute amount of each gas by integrating the pressure change in the container during the time.
[0020]
(9) An apparatus for measuring the absolute amount of each gas of a mixed gas in which gases having different vapor pressure characteristics are mixed,
A vacuum pump for exhausting the gas in the container at a constant exhaust speed, means for introducing the mixed gas into the container, and all gases except the gas having the lowest condensation temperature among the mixed gases introduced into the container. Cooling and condensing, gradually increasing the temperature of the condensed liquid or solid to vaporize each gas individually, a pressure gauge to measure the pressure in the container, and mixing for the gas with the lowest condensation temperature The absolute amount is obtained by the product of the pressure at the time of gas introduction and the exhaust speed, and for other gases, the exhaust speed is set as a proportional constant, and the container in the time from the start of vaporization of each gas to the end of vaporization is used. And an arithmetic means for obtaining the absolute amount of each gas by integrating the pressure change therein.
[0021]
(10) The absolute amount of each gas is measured by the mixed gas measuring device according to any one of the above ( 6) to (9), and the mixing ratio of the mixed gas is determined from the ratio of the absolute amount of each measured gas. It is characterized by comprising a calculating means for obtaining.
[0022]
The temperature of the condensed liquid or solid is preferably a method or apparatus for raising the temperature in a time sufficient for each gas to vaporize individually.
[0023]
The mixed gas can be condensed by disposing a target having good thermal conductivity near the gas inlet in the container and cooling it with a cooling means such as a refrigerator or liquid helium.
[0024]
Further, as the target, for example, copper or the like is preferably used. However, when a mixed gas at room temperature has been introduced, the target does not increase in temperature, and the refrigeration means is maintained at the same temperature as the frozen temperature. Various materials can be used as long as they have thermal conductivity capable of maintaining thermal contact, and the arrangement is not limited to the vicinity of the inlet as long as the above conditions are satisfied.
[0025]
As the shape of the target, various shapes such as a cylindrical shape can be adopted in order to ensure a large surface area.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
FIG. 1 is a configuration diagram of a measuring apparatus showing an embodiment of the present invention. This measuring apparatus is provided with a target 2 for condensing a mixed gas in a closed container 1. The target 2 can be cooled by a two-stage refrigerator (or liquid helium line) 3 as a cooling means and heated by a heater 4 as a temperature raising means, and the temperature of the target can be adjusted by the refrigerator 3 and the heater 4. Configure the means.
[0027]
The target 2 has a shape with a large surface area (for example, a cylinder), is formed of a material with good thermal conductivity (for example, copper), and is disposed in the vicinity of the gas inlet in the container. The temperature of the target 2 is adjusted so that the mixed gas (mixed gas) to be measured is trapped when all of the introduced mixed gas is condensed by being introduced into the container 1 through the surface of the target 2. Has been. Furthermore, the pressure in the container 1 can always be measured by an appropriate pressure gauge (for example, a baratron or a quartz gauge) 5.
[0028]
To measure the mixture ratio of the mixed gas and the absolute amount of each gas by the above apparatus, first, the container 1 is filled with an inert gas, for example, with helium gas at an appropriate pressure (for example, 0.1 atm). ). At this time, the target 2 is adjusted to a temperature of about 4K at which the mixed gas can be condensed.
[0029]
The container 1 may be evacuated instead of helium gas. The size of the container 1 is determined from the safety and the measurement range of the vacuum gauge by estimating the ultimate ultimate pressure when the total amount of the mixed gas is introduced. That is, the container 1 is enlarged when a large amount of mixed gas is introduced, when pressure measurement on the high pressure side is difficult, or when it is dangerous to fill the mixed gas at high pressure. Conversely, if it is desired to increase the sensitivity of the absolute amount measurement in cases other than the above, the container 1 is made smaller.
[0030]
Next, the mixed gas is introduced to the vicinity of the surface of the target 2 in the container 1 via a pipe. By this introduction, all gases other than helium are condensed on the target 2 by the refrigerator 3 (or liquid helium line) (all gases contained in the mixed gas are solidified into a solid state with a sufficiently low vapor pressure or vapor pressure is reduced). Liquefy to a sufficiently low liquid state).
[0031]
Thereafter, the temperature of the target 2 is increased at a constant rate (K / min) by the operation of the heater 4. Along with the temperature rise of the target 2 (elapse of time), a pressure rise from the initial pressure P0 is seen in the container 1 as shown in FIG. FIG. 2 shows a case in which no reaction occurs between components of the confused gas, the pressure should match the vapor pressure curve of the existing gas, and when a specific gas A is completely vaporized, the pressure rises at pressure P1. When the temperature rises further, the gas B starts to vaporize, the pressure rises in accordance with the vapor pressure curve, and the pressure rise stops at the pressure P2.
[0032]
At this time, by multiplying the difference between the ultimate pressure and the initial pressure by the volume of the container, the absolute amount of gas can be obtained by the following calculation. Furthermore, the mixing ratio can be determined from these absolute amounts. V in the formula is the volume of the container 1.
[0033]
[Expression 1]
Absolute amount of gas A = (P1-P0) × V
Absolute amount of gas B = (P2-P1) × V
Mixing ratio = A / B
In order to condense the mixed gas, it is preferable to use, for example, copper or the like as a target to be cooled by a cooling means such as a refrigerator or liquid helium, but when the mixed gas at room temperature has been introduced, the target is used. As long as there is thermal conductivity that can maintain thermal contact with the refrigeration means to such an extent that there is no temperature rise and is kept at the same temperature as the frozen temperature, various materials can be used, and the arrangement is also described above. As long as the conditions are satisfied, it is not limited to the vicinity of the inlet. As the shape of the target, various shapes such as a cylindrical shape can be adopted in order to ensure a large surface area.
[0034]
Moreover, it is preferable to raise the temperature of the condensed liquid or solid in a time sufficient for each gas to vaporize individually.
[0035]
(Embodiment 2)
If the introduced gas is composed of three or more gases and the reactivity between them is high, or if the introduced gas contains a gas that has explosive properties when the pressure increases, the absolute The amount can be determined.
[0036]
This measuring apparatus is shown in FIG. 1 is different from FIG. 1 in that a vacuum pump 6 is provided in the container 1 and the inside of the container is always evacuated by the vacuum pump 6 during measurement.
[0037]
In the above configuration, when the temperature of the target 2 is increased, a peak of the pressure P corresponding to each gas vapor can be confirmed, and each peak of the pressure increase is integrated over time, and the effective pumping speed of the pump is obtained. Each gas amount can be obtained by multiplying S (1 / time).
[0038]
With reference to FIG. 4, how to obtain the absolute amount in the case of a mixed gas of ozone and oxygen will be described. The vapor pressure curves of ozone and oxygen are known, the melting point is 80K for ozone, 55K for oxygen, the boiling point is 161K for ozone and 90K for oxygen. FIG. 4 shows the result of measuring the change in pressure P with an ion gauge when the target temperature is increased with the condensation temperature of the mixed gas being 30 K and the exhaust speed S being 200 liters / second.
[0039]
The absolute amount of oxygen at this time is measured from time t1 at which oxygen begins to vaporize (target is 30K) to time t2 at which oxygen vaporization is completed (target is 50K), as shown in the following equation. Can be obtained by integrating the exhaust velocity S at that time as a constant. Similarly, the absolute amount of ozone can be obtained by integrating the pressure P from the time t3 at which it starts to vaporize to the vaporization end time t4.
[0040]
[Expression 2]

[0041]
According to the measurement method and apparatus according to the present embodiment, exhaustion (exclusion from the container) is performed while measuring pressure changes in order from components with high vapor pressure. In such a case, the method is superior to the method of the first embodiment.
[0042]
As described in the first and second embodiments, it is preferable to cool all the gases to a temperature at which they can be trapped. However, when the trapped temperature is not trapped, it is not exhausted. Since the absolute amount can be obtained from the product of the pressure rise and the pumping speed when the gas is introduced, by the product of the pressure rise and the container volume when the gas is introduced, it becomes the object of measurement. Considering the gas trap temperature, it is possible to reduce the capacity required for the cooling means such as a refrigerator if necessary.
[0043]
As described above, according to the present invention, it is possible to measure the absolute amount and the mixing ratio of each gas of a mixed gas composed of an arbitrary gas, and particularly a highly reactive gas, for example, ozone, for semiconductor oxynitriding N _x O _y and NO _x , for example, mixed gas of NO ₂ and NO, chlorine-based gas for semiconductor etching, and highly reactive gas such as chlorine are used to measure safely by condensing once. be able to.
[0044]
【The invention's effect】
As described above, according to the present invention, all the mixed gas is condensed, and then the temperature is increased at an appropriate rate to vaporize each gas having a different vapor pressure temperature, and mixing is performed from the pressure change in the container at this time. Since the gas mixture ratio and absolute amount are obtained, the mixture ratio and absolute amount of any gas mixture can be measured.
[0045]
In addition, all gases except the gas with the lowest condensation temperature are measured by condensation and subsequent vaporization. For the gas with the lowest condensation temperature, the product of the pressure increase and the container volume at that time, or the product of the pressure and the exhaust velocity. If the absolute amount is obtained by this, the capacity required for the cooling means such as a refrigerator can be reduced.
[0046]
In addition, since the pressure gauge has a wide dynamic range (5 digits or more in the case of an ion gauge), the absolute amount can be accurately obtained even when the mixing ratio differs by a digit. Furthermore, even if it is unstable in a gaseous state or when the reactivity is high, it can be made stable by making it into a condensed state. Further, even when some components of the mixed gas are unknown, it is possible to determine the remaining gas species and the absolute amount by separating the vapor pressure curve of the known gas.
[Brief description of the drawings]
FIG. 1 is an apparatus configuration diagram showing Embodiment 1 of the present invention.
FIG. 2 shows an example of temperature-pressure measurement when there is no reaction between mixed gases.
FIG. 3 is an apparatus configuration diagram showing Embodiment 2 of the present invention.
FIG. 4 is a temperature-pressure measurement example in the second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Container 2 ... Target 3 ... Refrigerator 4 ... Heating heater 5 ... Pressure gauge 6 ... Vacuum pump

Claims

A method for measuring the absolute amount of each gas in a mixed gas in which gases having different vapor pressure characteristics are mixed,
The mixed gas is introduced into a container that has been evacuated in advance or into which an inert gas has been introduced, the mixed gas introduced into the container is cooled and condensed, and the temperature of the condensed liquid or solid is gradually increased. Each gas is vaporized individually, the volume of the container is set as a proportional constant, and the absolute amount of each gas is obtained by the product of the pressure change in the container when each gas is vaporized individually. Measuring method.

A method for measuring the absolute amount of each gas in a mixed gas in which gases having different vapor pressure characteristics are mixed,
The mixed gas is introduced into a container that has been evacuated in advance or into which an inert gas has been introduced, and all of the mixed gas introduced into the container is cooled and condensed except for the gas having the lowest condensation temperature. For the gas with the lowest condensation temperature, obtain the absolute amount by the product of the pressure rise at the time of introduction of the mixed gas and the volume of the container, and for other gases, gradually raise the temperature of the condensed liquid or solid to each gas. A method for measuring a mixed gas, characterized in that the gas is individually vaporized, the volume of the container is set as a proportional constant, and the absolute amount of each gas is obtained by a product of pressure changes in the container when each gas is vaporized individually.

A method for measuring the absolute amount of each gas in a mixed gas in which gases having different vapor pressure characteristics are mixed,
The mixed gas is introduced into a container that is evacuated at a constant pumping speed, the mixed gas introduced into the container is cooled and condensed, and the temperature of the condensed liquid or solid is gradually raised to individually supply each gas. Vaporization, the exhaust velocity is set as a proportional constant, and the absolute amount of each gas is obtained by integrating the pressure change in the container in the time from the start of vaporization to the end of vaporization. Gas measurement method.

A method for measuring the absolute amount of each gas in a mixed gas in which gases having different vapor pressure characteristics are mixed,
The mixed gas is introduced into a container that is evacuated at a constant pumping speed, and all of the mixed gas introduced into the container is cooled and condensed except for the gas having the lowest condensation temperature. For the other gases, the absolute amount is determined by the product of the pressure increase and the container volume when the mixed gas is introduced, and for other gases, the condensed liquid or solid is gradually heated to vaporize each gas individually, A method for measuring a mixed gas, characterized in that the absolute rate of each gas is obtained by integrating the change in pressure in the container in the time from the start of vaporization to the end of vaporization, with the exhaust velocity being a proportional constant. .

Mixing characterized by measuring the absolute amount of each gas by the method for measuring a mixed gas according to any one of claims 1 to 4 and obtaining the mixing ratio of the mixed gas from the ratio of the measured absolute amount of each gas Gas measurement method.

An apparatus for measuring the absolute amount of each gas of a mixed gas in which gases having different vapor pressure characteristics are mixed,
Means for introducing the mixed gas into a container that has been evacuated in advance or into which an inert gas has been introduced;
A temperature adjusting means for cooling and condensing the mixed gas introduced into the container, gradually elevating the temperature of the condensed liquid or solid, and vaporizing each gas individually;
A pressure gauge for measuring the pressure in the container;
An apparatus for measuring a mixed gas, characterized by comprising a calculation means for obtaining an absolute amount of each gas by a product of a pressure change in the container when the volume of the container is a proportional constant and each gas is vaporized individually. .

An apparatus for measuring the absolute amount of each gas of a mixed gas in which gases having different vapor pressure characteristics are mixed,
Means for introducing the mixed gas into a container that has been evacuated in advance or into which an inert gas has been introduced;
Temperature control means that cools and condenses all gases except the gas with the lowest condensation temperature among the mixed gas introduced into the container, and gradually raises the temperature of the condensed liquid or solid to vaporize each gas individually. When,
A pressure gauge for measuring the pressure in the container;
For the gas with the lowest condensation temperature, obtain the absolute amount by the product of the pressure rise at the time of introducing the gas mixture and the volume of the container. For other gases, the volume of the container is the proportional constant, and when each gas is vaporized individually An apparatus for measuring a mixed gas, comprising: an arithmetic means for obtaining an absolute amount of each gas by a product of pressure changes in the container.

An apparatus for measuring the absolute amount of each gas of a mixed gas in which gases having different vapor pressure characteristics are mixed,
A vacuum pump for exhausting the gas in the container at a constant exhaust speed;
Means for introducing the mixed gas into a container;
A temperature adjusting means for cooling and condensing the mixed gas introduced into the container, gradually elevating the temperature of the condensed liquid or solid, and vaporizing each gas individually;
A pressure gauge for measuring the pressure in the container;
Computation means for determining the absolute amount of each gas by integrating the pressure change in the container in the time from the start of vaporization individually until the end of vaporization, with the exhaust velocity as a proportional constant. A device for measuring mixed gas.

An apparatus for measuring the absolute amount of each gas of a mixed gas in which gases having different vapor pressure characteristics are mixed,
A vacuum pump for exhausting the gas in the container at a constant exhaust speed;
Means for introducing the mixed gas into a container;
Temperature control means that cools and condenses all gases except the gas with the lowest condensation temperature among the mixed gas introduced into the container, and gradually raises the temperature of the condensed liquid or solid to vaporize each gas individually. When,
A pressure gauge for measuring the pressure in the container;
For the gas with the lowest condensation temperature, the absolute amount is obtained by the product of the pressure at the time of introducing the mixed gas and the exhaust speed, and for other gases, the exhaust speed is set as a proportional constant, and each gas starts to vaporize individually. And a calculating means for calculating an absolute amount of each gas by integrating the pressure change in the container during the time from the end of vaporization to the end of vaporization.

An arithmetic unit for measuring the absolute amount of each gas by the mixed gas measuring device according to any one of claims 6 to 9 and obtaining a mixing ratio of the mixed gas from a ratio of the measured absolute amount of each gas is provided. An apparatus for measuring a mixed gas characterized by the above.