JPH0665192B2 - Electronic temperature measuring device - Google Patents
Electronic temperature measuring deviceInfo
- Publication number
- JPH0665192B2 JPH0665192B2 JP62251201A JP25120187A JPH0665192B2 JP H0665192 B2 JPH0665192 B2 JP H0665192B2 JP 62251201 A JP62251201 A JP 62251201A JP 25120187 A JP25120187 A JP 25120187A JP H0665192 B2 JPH0665192 B2 JP H0665192B2
- Authority
- JP
- Japan
- Prior art keywords
- probe
- current
- electron
- voltage
- circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Plasma Technology (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明はプラズマ中の電子温度を測定する装置に係わ
り、特に、プラズマ中にプローブを挿入して電子温度を
高信頼、高速かつ広範囲に測定する装置に関する。Description: TECHNICAL FIELD The present invention relates to an apparatus for measuring electron temperature in plasma, and in particular, a probe is inserted into plasma to measure the electron temperature with high reliability, at high speed, and in a wide range. Related to the device.
（従来技術および問題点） プラズマ中の荷電粒子の速度分布がマックスウェル分布
に従う場合のプローブ電圧電流特性が、第２図に示され
ており、更に対数電流値に対するプローブ特性が第３図
に示されている。プローブ電流値が零となる浮動電位Vf
よりも低い電圧領域が正イオン電流飽和領域となり、浮
動電位Vfと第３図における変曲点である空間電位との間
が電子電流反発領域となり、空間電位よりも高い電圧領
域が電子電圧領域となる。電子電流反発領域において
は、プローブ電流は次式で表される。(Prior Art and Problems) FIG. 2 shows the probe voltage-current characteristic when the velocity distribution of charged particles in plasma follows the Maxwell distribution, and FIG. 3 shows the probe characteristic with respect to the logarithmic current value. Has been done. Floating potential Vf at which the probe current value becomes zero
A voltage region lower than that is a positive ion current saturation region, an electron current repulsion region is between the floating potential Vf and a space potential which is an inflection point in FIG. 3, and a voltage region higher than the space potential is an electron voltage region. Become. In the electron current repulsion region, the probe current is expressed by the following equation.
ip＝J exp〔−ｅ（Vs−Vp）／k Te〕 ……（１） ここで、ipはプローブ電流、Vpはプローブ電圧、Vsは空
間電位、ｅは電子の電荷、ｋはボルツマン定数、Teは電
子温度、そしてＪは電子密度、電子の電荷および質量、
プローブ電極の形状、電子温度等によって決まる物理量
である。ip = J exp [−e (Vs−Vp) / k Te] (1) where ip is the probe current, Vp is the probe voltage, Vs is the space potential, e is the electron charge, k is the Boltzmann constant, Te is electron temperature, and J is electron density, electron charge and mass,
It is a physical quantity determined by the shape of the probe electrode, electron temperature, and the like.
（１）式より、電子温度Teに関し、次式を得る。From the equation (1), the following equation is obtained for the electron temperature Te.
ここで、ΔVpはプローブ電圧の変化分、Δlog ipはプロ
ーブ電圧をΔVpだけ変化させたときのプローブ電流変化
分の対数値である。 Here, ΔVp is the change amount of the probe voltage, and Δlog ip is the logarithmic value of the change amount of the probe current when the probe voltage is changed by ΔVp.
このため、電子温度を得るために従来は、１）プローブ
電圧に対するプローブ電流の対数特性を測定し、その傾
斜から求める。２）プローブ電圧に交流電圧ΔVpを重畳
し、このとき流れるプローブ電流の変化分を検波し、そ
の対数値を交流電圧の比から求める。などの方法が採ら
れてきた。しかし、１）の方法は、測定時間や人的判断
を必要とし、また、２）の方法は、検波回路の時定数に
応じた遅れを生じるため、応答性が悪く、更に、電子電
流反発領域を逸脱する可能性を有するため測定方法自体
の信頼性が乏しいこと、などの問題を有していた。ま
た、上記２つの方法とも、その適用範囲は低温プラズマ
に限定され、測定温度範囲が狭いという共通の問題があ
った。Therefore, in order to obtain the electron temperature, conventionally, 1) the logarithmic characteristic of the probe current with respect to the probe voltage is measured, and the logarithmic characteristic is obtained. 2) Superimpose the AC voltage ΔVp on the probe voltage, detect the change in the probe current that flows at this time, and obtain the logarithmic value from the AC voltage ratio. Etc. have been adopted. However, the method 1) requires measurement time and human judgment, and the method 2) causes a delay according to the time constant of the detection circuit, resulting in poor responsiveness and further the electron current repulsion region. Therefore, there is a problem that the reliability of the measurement method itself is poor due to the possibility of deviating from the above. Further, both of the above methods have a common problem that the applicable range is limited to low temperature plasma and the measurement temperature range is narrow.
（発明が解決しようとする問題点） 一般に、プローブ電圧電流特性は正イオン電流飽和領
域、電子電流反発領域および電子電流飽和領域の３つの
区間に大別できる。このうち（１）式が成り立つのは電
子電流反発領域であって、これ以外の区間において、
（２）式に基づき計測された電子温度は誤った結果を示
す。(Problems to be Solved by the Invention) In general, the probe voltage-current characteristics can be roughly classified into three sections of a positive ion current saturation region, an electron current repulsion region and an electron current saturation region. Of these, the formula (1) is satisfied in the electron current repulsion region, and in the other sections,
The electron temperature measured based on the equation (2) shows an incorrect result.
本発明の目的は、プローブ電圧の変化範囲を電子電流反
発領域に限定するもので、しかもプローブ電圧を微少時
間だけ変化させ、これに対応するプローブ電流の変化分
を抽出することにより、高信頼、高速かつ広範囲の電子
温度を測定することのできる装置を提供することにあ
る。An object of the present invention is to limit the change range of the probe voltage to the electron current repulsion region, and further change the probe voltage only for a minute time, and extract the change amount of the probe current corresponding to this, to obtain high reliability, An object of the present invention is to provide a device capable of measuring electron temperature in a wide range at high speed.
（問題を解決するための手段） 上述した問題点は、浮動電圧を予め測定し、この測定値
を基準としてプローブ電圧を発生することにより解決さ
れる。具体的には、浮動電位検出手段、任意可変振幅パ
ルス発生手段、前記浮動電位検出信号と前記パルス電圧
の加算回路、この加算回路の出力電圧をプローブに印加
したときに流れるプローブ電流の検出回路、この電流検
出信号と前記パルス電圧に関する演算処理回路を備える
本発明の電子温度測定装置によって解決される。(Means for Solving the Problem) The above-mentioned problems are solved by measuring the floating voltage in advance and generating the probe voltage based on this measured value. Specifically, a floating potential detecting means, an arbitrary variable amplitude pulse generating means, an adding circuit of the floating potential detecting signal and the pulse voltage, a detection circuit of a probe current flowing when the output voltage of the adding circuit is applied to the probe, This is solved by the electronic temperature measuring device of the present invention, which is provided with an arithmetic processing circuit for the current detection signal and the pulse voltage.
（作用および発明の効果） 実験室プラズマやプラズマプロセッシング用などの工業
用プラズマではガスの種類や圧力、放電条件等によっ
て、その状態が著しく変化する。これらプラズマの状態
変化はプローブ特性に反映し、電子電流反発領域の移
動、電子温度変化、電子密度変化等となって現れる。(Functions and Effects of the Invention) In laboratory plasma and industrial plasma for plasma processing, the state thereof remarkably changes depending on the type of gas, pressure, discharge conditions, and the like. These changes in the state of the plasma are reflected in the probe characteristics and appear as movement of the repulsion region of electron current, changes in electron temperature, changes in electron density, and the like.
本発明においては、正イオン電子電流飽和領域と電子電
流反発領域の境界となる浮動電位を検出し、これより、
電子電流反発領域において、プローブ電圧を電子温度の
範囲に応じて微少時間変化させて、プローブ電流を検出
し、演算処理して電子温度を得るもので、測定法自体の
信頼性が高く、高速性に富み、高温プラズマへの適用性
を有する汎用性の高い電子温度測定装置が開発できた。In the present invention, the floating potential at the boundary between the positive ion electron current saturation region and the electron current repulsion region is detected, and from this,
In the electron current repulsion region, the probe voltage is changed for a minute time according to the electron temperature range, the probe current is detected, and the electron temperature is obtained by arithmetic processing. The measurement method itself has high reliability and high speed. It was possible to develop a versatile electron temperature measuring device that is highly versatile and has applicability to high-temperature plasma.
（実施例） 以下に、本発明の一実施例である第１図のブロック図お
よび第２図および第３図のプローブ特性を参照しつつ詳
細に説明する。(Embodiment) Hereinafter, one embodiment of the present invention will be described in detail with reference to the block diagram of FIG. 1 and the probe characteristics of FIG. 2 and FIG.
プラズマ中に浮動電位検出用プローブP1とプローブ電流
検出用プローブP2を挿入し、第２図および第３図に示さ
れる様にプラズマ電流ipが零となるアノードＡを基準と
するプローブP1のプラズマの浮動電位Vfを浮動電位検出
回路１により検出する。パルス発生回路２は互いに電圧
が異なり、かつ電子電流反発領域を越えない値の二つの
パルス電圧Vp1およびVp2を順次発生す栄。この発生され
たパルス電圧Vp1およびVp2は前記検出された浮動電位Vf
と加算回路３において加算された後、プローブP2に印加
される。印加電圧Vf＋Vp1およびVf＋Vp2にそれぞれ応じ
て生じたプローブ電流ip1およびip2は電流検出回路４に
おいて検出される。演算回路５は上記第（２）式に基づ
いて、得られたプローブ電流ip1およびip2の値の差の対
数値Δlog ipと、二つのパルス電圧Vp1およびVp2の値の
差ΔVpとを求め、さらに両者の比を求め、電子温度に対
応した出力を発生する。As shown in FIGS. 2 and 3, the floating potential detecting probe P 1 and the probe current detecting probe P 2 are inserted into the plasma, and the probe P 1 is based on the anode A at which the plasma current ip becomes zero. The floating potential Vf of the plasma is detected by the floating potential detection circuit 1. The pulse generating circuit 2 sequentially generates two pulse voltages Vp 1 and Vp 2 having different voltages and having a value not exceeding the electron current repulsion region. The generated pulse voltages Vp 1 and Vp 2 are the detected floating potential Vf.
Is added in the adding circuit 3 and then applied to the probe P 2 . The probe currents ip 1 and ip 2 generated according to the applied voltages Vf + Vp 1 and Vf + Vp 2 are detected by the current detection circuit 4. The arithmetic circuit 5 calculates the logarithmic value Δlog ip of the difference between the values of the probe currents ip 1 and ip 2 and the difference ΔVp between the values of the two pulse voltages Vp 1 and Vp 2 based on the equation (2). Then, the ratio between the two is calculated to generate an output corresponding to the electron temperature.
なお、浮動電圧ばかりでなく、空間電位をも予め検出し
て、パルス電圧値がこれを越えない値にし、プローブ電
圧が確実に電子電流反発領域内に位置するようにしても
よい。It should be noted that not only the floating voltage but also the space potential may be detected in advance so that the pulse voltage value does not exceed this value, and the probe voltage may be reliably positioned within the electron current repulsion region.
第１図は、本発明に基づく電子温度測定装置の回路を示
すブロック図、 第２図は、プローブ（VP−iP）特性を示すグラフ、 第３図は、プローブ（VP−log iP）特性を示すグラフ。 （符号の説明） P1、P2……プローブ電極、 Ａ……アノード、 Te……電子温度、 １……浮動電位検出回路、 ２……パルス電圧回路、 ３……加算回路、 ４……電流検出回路、 ５……演算回路。FIG. 1 is a block diagram showing a circuit of an electronic temperature measuring device according to the present invention, FIG. 2 is a graph showing probe (V P −i P ) characteristics, and FIG. 3 is a probe (V P −log i). P ) Graph showing characteristics. (Explanation of symbols) P 1 , P 2 ... probe electrode, A ... anode, Te ... electron temperature, 1 ... floating potential detection circuit, 2 ... pulse voltage circuit, 3 ... addition circuit, 4 ... Current detection circuit, 5 ... Operation circuit.
Claims (1)
生手段、前記浮動電位検出手段により検出された浮動電
位信号と前記パルス電圧の加算回路、この加算回路の出
力電圧をプローブに印加したときに流れるプローブ電流
の検出回路、この電流検出信号と前記パルス電圧に関す
る演算処理回路を備える電子温度測定装置。1. A floating potential detecting means, a variable amplitude pulse voltage generating means, an adding circuit of the floating potential signal detected by the floating potential detecting means and the pulse voltage, and when an output voltage of the adding circuit is applied to a probe. An electronic temperature measuring device comprising a detection circuit for a flowing probe current and an arithmetic processing circuit for the current detection signal and the pulse voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62251201A JPH0665192B2 (en) | 1987-10-05 | 1987-10-05 | Electronic temperature measuring device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62251201A JPH0665192B2 (en) | 1987-10-05 | 1987-10-05 | Electronic temperature measuring device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0195497A JPH0195497A (en) | 1989-04-13 |
| JPH0665192B2 true JPH0665192B2 (en) | 1994-08-22 |
Family
ID=17219191
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62251201A Expired - Fee Related JPH0665192B2 (en) | 1987-10-05 | 1987-10-05 | Electronic temperature measuring device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0665192B2 (en) |
-
1987
- 1987-10-05 JP JP62251201A patent/JPH0665192B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0195497A (en) | 1989-04-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |