CN101251487A - Method and device for detecting F atomic concentration - Google Patents

Abstract

The invention relates to a detection method and a detection device for the F atom concentration, wherein, a titration HP absorption spectroscopy is adopted for measuring the F atom concentration; a route selection electric excited continuous wave HP laser is adopted to be a probe light source; the absorption spectrum intensity of HF molecules in a flow field is measured through an infrared window. Because the concentration of F atoms which are dissociated by a system to be detected is certain, when the flow rate of infused hydrogen is increased gradually, the concentration of HF molecules generated can be increased along with the increase of the flow rate until all the F atoms are reacted completely, and the absorption spectrum intensity A of the HF molecules can also be increased gradually to a stable vale; when A is just a maximum value, the corresponding hydrogen flow rate is equal to the F atom concentration. Moreover, the F atom concentration can be directly calculated through the absorption spectrum intensity of the HF molecules after related parameters are obtained by fitting of data which is obtained by titration processes for many times. The invention is a detection method and a detection device for the F atom concentration with simple and convenient operation, simple and compact structure, low cost, high measuring precision and good stability.

Description

The detection method of F atomic concentration and pick-up unit

Technical field

The present invention is mainly concerned with the detection range of F atom, refer in particular to a kind of detection method and pick-up unit of F atomic concentration, be particularly useful for the diagnosis of electric excitation HF/DF chemical laser, full gas phase Chemical oxygen-iodine laser and contain the F plasma etching processing siliceous semiconductor applications.

Background technology

For electric excitation HF/DF laser instrument and full gas phase Chemical oxygen-iodine laser, former suboutput of F and productive rate are the main performance index of its core devices-discharge tube, be the direct deciding factor of laser power and efficient, F atom online measuring technique is significant for improving and optimizating of laser instrument.For the semiconductor etching manufacture field, be to improve working (machining) efficiency and effect, the research of then being devoted to how efficiently produce the F atom always and improving the F atomic concentration in the plasma is starved of simply effectively and F atomic concentration measuring method accurately.

Since relate to military field, few to the open report document that F atomic concentration in HF/DF laser instrument and the full gas phase Chemical oxygen-iodine laser is measured, and containing F plasma etching processing semiconductor field, for F atom detection technique extensive studies is arranged.Basically can reduce following four class methods: actinometry method (Jenq J S et al.PlasmaSources Sci.Technol.3,154-161,1994), mass spectrometer mensuration (A.Tserepi, et al.J.Vac.Sci.Technol.A 15.6., 3120, Nov/Dec 1997), F atomic absorption spectrum mensuration (K.Sasaki, Y.Kawai, and K.Kadota.Review Of Scientific Instruments Vol.70, No.1,76-81, January 1999), titrimetry.Titrimetry is divided into a variety of specific implementations again according to titration gas, detection thing, detection mode etc., typical as: nitrine acid system (Liping Duo, Shukai Tang, Haijun Yu.CHINESEOPTICS LETTERS/Vol.4, No.3,170-172, March 10,2006), I atomic absorption spectrography (AAS) (GeraldC.Manke II, Thomas L.Henshaw, Timothy J.Madden.AIAA Journal Vol.39, No.3, March2001) or the like method.

The actinometry method is promptly utilized the corresponding relation of F atom and Ar atom particular spectral lines radiation intensity and its concentration, is calculated the method for F atomic concentration by radiation spectrum intensity and Ar concentration.F atom (703.7nm) radiation intensity I _FAnd Ar (750.4nm) radiation intensity I _ArThere is following approximation relation:

$\frac{N_F}{N_{\mathrm{Ar}}}=K\frac{I_F}{I_{\mathrm{Ar}}}$

Its advantage of actinometry method is a non-cpntact measurement.Its shortcoming has: 1. the value of coefficient of ratio K needs to obtain indirectly by theoretical calculation or with other measuring methods.2. the K value is relevant with temperature, thus be fit to the measurement of F atomic concentration in the steady-state plasma, and temperature generally all changes to some extent in the actual measurement.3. since the radiation spectral line generally a little less than, and be positioned at visible light wave range, the signal to noise ratio (S/N ratio) of signal is very low, needs signal Processing.

The mass spectrometer mensuration is determined the F atomic concentration by m/e=19 (F ion) signal intensity in the measurement mass spectrometer.The part conversion coefficient relatively is divided by by two kinds of sample measurement results and eliminates, and all the other conversion coefficients are long-pending relevant with two sample ionization cross of selection.The shortcoming of the method has: 1. need difference per sample to determine conversion coefficient, and the long-pending value of ionization cross also is more difficult to get.2. the mass spectrometer that need use belongs to exact instrument, and its price is very high, and associated operation is also complicated.3. it is more to simplify hypothesis in theory, and measuring accuracy can not get ensureing.

F atomic absorption spectrum mensuration is promptly measured F atom particular spectral lines absorption intensity and line style thereof in the plasma, more directly by calculating the method that obtains the F atomic concentration.Its advantage is that noncontact is directly measured, and shortcoming is the reason owing to spectral line wave band (far infrared, ultraviolet), and alternative probe light source is few, needs high-precision spectro-metre to come the absorbance spectrum line style in addition.

Titrimetry is promptly utilized and can be consumed the F atom with F atom rapid-action titration gas, detects the output of certain reactant or reaction product, and the flow of titration gas can be extrapolated F atom flow (concentration) when reaching extreme value by detected value.The titrimetry method is simple, and is workable, and the precision height is a detection range method very commonly used, but unique deficiency is to need to introduce the titration material, may cause interference to measuring thing.And in the titration method that is suitable for the detection of F atomic concentration, employed hydrazoic acid is at normal temperatures and pressures for having intense stimulus stink, volatile colourless toxic liquid in the nitrine acid system, when strong solution and vaporized state the heating or be impacted and can set off an explosion, so method has certain danger; Utilize HI as titration gas in the I atomic absorption spectrography (AAS), and the price of HI gas is very expensive, the commercial Application cost is too high.

Generally speaking, above-mentioned the whole bag of tricks can be walked out the few of laboratory actual input commercial Application because of cost, operability, precision or the like multiple reason.

Summary of the invention

The problem to be solved in the present invention just is: at the technical matters that prior art exists, the invention provides a kind of easy and simple to handle, simple and compact for structure, with low cost, measuring accuracy is high, the detection method and the pick-up unit of the F atomic concentration of good stability.

For solving the problems of the technologies described above, the solution that the present invention proposes is: a kind of detection method of F atomic concentration is characterized in that step is:

(1), in titration apparatus, feeds the mixed gas that contains the F atom, the both sides of titration apparatus are provided with Infrared Lens as transmission window, the probe light that the probe light source produces is after the semi-transparent semi-reflecting lens beam splitting, reflected light utilizes the infrared power detector to detect the power signal intensity of this moment as basal signal S successively by transmitting behind the Infrared Lens of two sides ₀,

(2), in titration apparatus, feed gas H ₂, contain the mixed gas and the H of F atom ₂Rapid reaction F+H takes place ₂→ HF+H;

The probe light that the probe light source produces is after the semi-transparent semi-reflecting lens beam splitting, reflected light passes through an Infrared Lens rear portion beam split by the HF molecule absorption, remaining light transmits through the another side Infrared Lens, utilizes the infrared power detector to detect the power signal intensity of this moment as actual signal S ₁, transmitted light shines directly on another infrared power detector, and the power signal intensity that detects this moment is as reference light signal S ₂

(3), by 1. obtain HF molecular absorption spectrum intensity A with following formula:

$A=\frac{S_0-S_1}{{\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="S2008100309274E00021.png"\; state="\{\{state\}\}">S</figure-callout>}}_2}$ ①；

(4), increase progressively gas H ₂The flow that injects, the value of record HF molecular absorption spectrum intensity A is with gas H ₂The data of fluctuations in discharge are finished a titration process and are obtained HF absorption spectrum intensity with injecting H ₂The curve of fluctuations in discharge, flex point place, i.e. H in this curve ₂Pairing H during with the lucky complete reaction of F atom ₂Flow H (mol/s) equals to contain the flow of F atom in the mixed gas of F atom, in conjunction with the flow velocity v (m/s) of air-flow and the sectional area S (m of passage ²), utilize following formula 2. just can obtain F atomic concentration ρ (mol/m ³):

$\mathrm{\&rho;}=\frac{H}{v\&times;\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="S2008100309274E00021.png"\; state="\{\{state\}\}">S</figure-callout>}}$ ②。

The present invention further repeatedly feeds the mixed gas that contains the F atom of variable concentrations, repetition above-mentioned steps (1), (2), (3), (4) can obtain a plurality of data points about F atomic concentration ρ and HF absorption spectrum intensity A, because 3. the relation of F atomic concentration ρ and HF absorption spectrum intensity A satisfies following formula, 3. through type can obtain the value of constant α; When actual measurement, only need in titration apparatus, to feed excessive gas H ₂, measure the value of a HF molecular absorption spectrum intensity A, 3. through type can obtain F atomic concentration ρ (mol/m again ³);

$\mathrm{\&rho;}=-\frac{1}{\mathrm{\&alpha;}}\mathrm{<figure-callout\; id="3"\; label="ln\; A"\; filenames="S2008100309274E00021.png"\; state="\{\{state\}\}">ln</figure-callout>}A$ ③

In the formula: α=S φ (υ) L, the shape of the tested gas absorption spectrum line of linear function φ (υ) expression, S represents the spectral line absorption intensity, L be the single-frequency laser bundle the length by tested gas, v is the frequency of single-frequency laser bundle.

The distance of probe light to the two infrared power detector that described probe light source produces equates.

A kind of pick-up unit of F atomic concentration, it is characterized in that: it comprises titration apparatus, the acquisition of signal acquisition system, probe light source and semi-transparent semi-reflecting lens, described titration apparatus comprises shell body, shell body is hollow form and forms gas channel, symmetria bilateralis offers two transmission windows on the shell body, the transmission window place is equiped with Infrared Lens, offer a plurality of hydrogen filling orifices on the shell body, described acquisition of signal acquisition system comprises computing machine and the first infrared power detector that links to each other with computing machine and the second infrared power detector, the probe light that the probe light source produces forms two-way light after the semi-transparent semi-reflecting lens beam splitting, by being transmitted to the first infrared power detector behind the Infrared Lens of two sides, transmitted light is directly incident on the second infrared power detector to reflected light successively.

The position corresponding with Infrared Lens offers the nitrogen filling orifice on the described transmission window, described nitrogen filling orifice is communicated with gas channel by two or more jet slits, this jet slit is parallel with minute surface, and the nitrogen filling orifice links to each other with the nitrogen air supply source by gas circuit.

The inlet end of described gas channel links to each other by gas circuit and the F atom device that dissociates, and endpiece links to each other with the decontamination tower by gas circuit.

Described probe light source adopts route selection electric excitation CW HF laser instrument.

The probe light that described probe light source produces equates to the distance of the first infrared power detector and the second infrared power detector.

Compared with prior art, advantage of the present invention just is:

1, the detection method of F atomic concentration of the present invention and pick-up unit have easy and simple to handle, simple and compact for structure, with low cost, advantages such as measuring accuracy is high, good stability;

2, the detection method of F atomic concentration of the present invention and pick-up unit are not only applicable to single measurement, also are applicable to repeatedly to measure and the online in real time measurement simple, the easily popularization of principle;

3, the detection method of F atomic concentration of the present invention and pick-up unit adopt titrimetry to measure, its principle simple, intuitive, and easy and simple to handle, data are handled easily, and measurement result is with a high credibility;

4, the detection method of F atomic concentration of the present invention and pick-up unit, probe light source spectral line and HF molecular absorption line mate fully, and the absorption spectra measurement result is very reliable, measurement result precision height;

5, the detection method of F atomic concentration of the present invention and pick-up unit, a whole set of technical scheme light path is simple, and equipment needed thereby is few, and all easy and simple to handle, and measurement environment is not had specific (special) requirements;

6, the detection method of F atomic concentration of the present invention and pick-up unit, whole cost is cheap relatively, drops into having a extensive future of practical application.

Description of drawings

Fig. 1 is the schematic flow sheet of the inventive method;

Fig. 2 is the structural representation of apparatus of the present invention;

Fig. 3 is the schematic layout pattern one of hydrogen filling orifice on the shell body among the present invention;

Fig. 4 is the schematic layout pattern two of hydrogen filling orifice on the shell body among the present invention;

Fig. 5 is the structural representation of titration apparatus among the present invention;

Fig. 6 is that HF absorption spectrum intensity is with injecting the curve synoptic diagram that hydrogen flowing quantity changes.

Marginal data

1, titration apparatus

101, shell body 102, gas channel

103, transmission window 104, Infrared Lens

105, hydrogen filling orifice 106, nitrogen filling orifice

107, nitrogen air supply source 108, hydrogen air supply source

2, acquisition of signal acquisition system

201, computing machine 202, the first infrared power detector

203, the second infrared power detector 204, data acquisition card

3, probe light source 4, semi-transparent semi-reflecting lens

5, dissociate device 501, fluorine source and assist gas air supply source of F atom

6, decontamination tower 601, mechanical pump

7, flow controller

Embodiment

Below with reference to the drawings and specific embodiments the present invention is described in further details.

As depicted in figs. 1 and 2, the detection method of a kind of F atomic concentration of the present invention the steps include:

(1), in titration apparatus, feeds the mixed gas that contains the F atom, the both sides of titration apparatus are provided with Infrared Lens as transmission window, the probe light that the probe light source produces is after the semi-transparent semi-reflecting lens beam splitting, reflected light utilizes the infrared power detector to detect the power signal intensity of this moment as basal signal S successively by transmitting behind the Infrared Lens of two sides ₀, this is because the absorption reflection of infrared window itself etc. can lose part probe light, so do not injecting H ₂Space-time is surveyed once;

(2), in titration apparatus, feed gas H ₂, contain the mixed gas and the H of F atom ₂Rapid reaction F+H takes place ₂→ HF+H;

When the F atomic current through H ₂During filling orifice, with the hydrogen generation rapid reaction of injecting, the HF molecule major part of generation is in vibrational energy level, but through the very short time (less than 10 ^-5S) after, the HF molecule will all be returned to ground state basically.Make the appropriate distance of maintenance between infrared window and the hydrogen filling orifice, when making air-flow arrive infrared window, the HF molecule all is in ground state basically, adopts route selection electric excitation HF laser instrument as the probe light source then, measures the absorption spectrum intensity of HF molecule in the flow field by infrared window.The probe light that the probe light source produces is after the semi-transparent semi-reflecting lens beam splitting, reflected light passes through an Infrared Lens rear portion beam split by the HF molecule absorption, remaining light transmits through the another side Infrared Lens, utilizes the infrared power detector to detect the power signal intensity of this moment as actual signal S ₁, transmitted light is directly incident on another infrared power detector, and the power signal intensity that detects this moment is as reference light signal S ₂

(3), by 1. obtain HF molecular absorption spectrum intensity A with following formula:

$A=\frac{S_0-S_1}{{\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="S2008100309274E00021.png"\; state="\{\{state\}\}">S</figure-callout>}}_2}$ ①；

(4), increase progressively gas H ₂The flow that injects, the value of record HF molecular absorption spectrum intensity A is with gas H ₂The data of fluctuations in discharge are finished a titration process and are obtained HF absorption spectrum intensity with injecting H ₂The curve of fluctuations in discharge, flex point place, i.e. H in this curve ₂Pairing H during with the lucky complete reaction of F atom ₂Flow H (mol/s) equals to contain the flow of F atom in the mixed gas of F atom, in conjunction with the flow velocity v (m/s) of air-flow and the sectional area S (m of passage ²), utilize following formula 2. just can obtain F atomic concentration ρ (mol/m ³):

$\mathrm{\&rho;}=\frac{H}{v\&times;\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="S2008100309274E00021.png"\; state="\{\{state\}\}">S</figure-callout>}}$ ②。

In the practical application, less if required F atomic concentration is measured number of times, can directly use above-mentioned titrimetry to finish measurement.As if needing repeatedly or the online in real time measurement,,, need obtain calibration curve about HF molecular absorption spectrum intensity and F atomic concentration for making the actual measurement simple and fast because the required measuring process of titrimetry is more.

By Beer～Lambert law, frequency is that the single-frequency laser bundle of v is that L, concentration are the tested gas of ρ (molar percentage) by length, and 4. tested gas satisfy following expression to the absorption spectrum intensity of laser:

$A={\left(\frac{I_t}{I_0}\right)}_{\mathrm{\&upsi;}}=\exp [-\mathrm{S\&rho;\&phi;}\left(\mathrm{\&upsi;}\right)L]$ ④

Wherein: I ₀With I be respectively incident laser and transmission laser intensity; The shape of the tested gas absorption spectrum line of linear function φ (υ) expression, S represents the spectral line absorption intensity.The value of supposing S, φ (υ) and L is constant substantially in measuring process, makes α=S φ (υ) L, following relational expression is then arranged 3.:

$\mathrm{\&rho;}=-\frac{1}{\mathrm{\&alpha;}}\mathrm{<figure-callout\; id="3"\; label="ln\; A"\; filenames="S2008100309274E00021.png"\; state="\{\{state\}\}">ln</figure-callout>}A$ ③

Even measure the value of constant α, just can directly calculate F atomic concentration ρ by the A value by test.

Therefore, in another embodiment, change condition of work, the F atomic concentration is changed, can repeatedly feed the mixed gas that contains the F atom of variable concentrations, repeat above-mentioned steps (1), (2), (3), (4) and can obtain a plurality of data points about F atomic concentration ρ and HF absorption spectrum intensity A, owing to 3. the relation of F atomic concentration ρ and HF absorption spectrum intensity A satisfies following formula, by the data processing software through type 3. match can obtain the value of constant α; When actual measurement, only need in titration apparatus, to feed excessive gas H ₂, measure the value of a HF molecular absorption spectrum intensity A, directly 3. through type can obtain F atomic concentration ρ (mol/m again ³), reach the purpose that online in real time is measured;

$\mathrm{\&rho;}=-\frac{1}{\mathrm{\&alpha;}}\mathrm{<figure-callout\; id="3"\; label="ln\; A"\; filenames="S2008100309274E00021.png"\; state="\{\{state\}\}">ln</figure-callout>}A$ ③

In the formula: α=S φ (υ) L, the shape of the tested gas absorption spectrum line of linear function φ (υ) expression, S represents the spectral line absorption intensity, L be the single-frequency laser bundle the length by tested gas, v is the frequency of single-frequency laser bundle.

Wherein, the distance of probe light to two an infrared power detector of probe light source generation is equated.

As Fig. 2, Fig. 3, Fig. 4 and shown in Figure 5, the pick-up unit of a kind of F atomic concentration of the present invention, it comprises titration apparatus 1, acquisition of signal acquisition system 2, probe light source 3 and semi-transparent semi-reflecting lens 4, titration apparatus 1 comprises shell body 101, shell body 101 is hollow form and forms gas channel 102, symmetria bilateralis offers two transmission windows 103 on the shell body 101, transmission window 103 places are equiped with Infrared Lens 104, offer a plurality of hydrogen filling orifices 105 on the shell body 101, hydrogen filling orifice 105 links to each other with hydrogen air supply source 108 by pipeline; Acquisition of signal acquisition system 2 comprises computing machine 201 and the first infrared power detector 202 and the second infrared power detector 203 that link to each other with computing machine 201 by data acquisition card 204, the probe light that probe light source 3 produces forms two-way light after the semi-transparent semi-reflecting lens beam splitting, by being transmitted to the first infrared power detector 202 behind the two sides Infrared Lens 104, transmitted light is directly incident on the second infrared power detector 203 to reflected light successively.The probe light that probe light source 3 produces equates to the distance of the first infrared power detector 202 and the second infrared power detector 203.Probe light source 3 adopts route selection electric excitation CW HF laser instrument.In the specific embodiment, the route selection electric excitation CW HF laser instrument (Wang Hongyan that probe light source 3 can select for use directional energy research institute of the National University of Defense technology to make, the research of the infrared multiband chemical laser of electric excitation continuous wave, National University of Defense Technology's doctorate paper).Regulate the angle of grating, (wavelength is respectively 2.6397 μ m, 2.6727 μ m, 2.7074 μ m, 2.7440 μ m) selects the spectral line output that power is bigger from four spectral lines such as P1 (4), P1 (5), P1 (6), P1 (7), and output power is about 1 watt.The first infrared power detector 202 and the second infrared power detector 203 are all selected the vulcanized lead power detector of Beijing Saifan Photoelectric Instrument Co., Ltd for use, and model is 7ID4321.The first infrared power detector 202 links to each other with computing machine 201 by data acquisition card 204 with the second infrared power detector 203, and data acquisition card 204 is selected the A/D data collecting card of NI company for use.

The gas that contains the F atom (is called for short the fluorine source, as NF ₃, SF ₆, CF ₄, F ₂Deng) with complementary gas (as He, Ar, N ₂, O ₂, C ₂H ₆Deng) provide by fluorine source and assist gas air supply source 601, feeding the F atom by gas circuit dissociates in the device 6, by discharge, microwave, burning, radio frequency or the like mode, produce the mixed airflow (be grouped into by multiple one-tenth, state is in the mixture between plasma state and the gas) that contains the F atom.With combination S F commonly used in the electric excitation HF/DF chemical laser ₆(fluorine source), He and O ₂(complementary gas) is example, in discharge tube, and fluorine source SF ₆Be dissociated into F atom and many sulfur fluorides SFi

(i≤5); He gas is used as thinning agent, and plays the effect that reduces the discharge tube starting voltage, keeps discharge; O ₂In order to react away SF ₆The solid-state S simple substance that produces in the dissociation process, and pass through displacement reaction: SF _i+ O ₂→ SF _I-2O ₂+ 2F (i=2 ..., 6), the productive rate of increase F atom.

The mixed airflow that contains the F atom flow in the titration apparatus 2 under the effect that mechanical pump is bled.Electric excitation HF/DF laser instrument itself possesses H in the relevant position ₂Injection device is so only need infrared window in the titration apparatus 2.For the titration apparatus 2 of full gas phase Chemical oxygen-iodine laser and semiconductor etching device, then infrared window and H ₂Filling orifice all needs.Referring to Fig. 3 and shown in Figure 4, according to the difference (being generally rectangular channel or circular hole passage) of gas channel 102 shapes, H ₂The distribution mode of filling orifice also can have dual mode, and rectangular channel generally adopts two rows hydrogen filling orifice 105 to inject, and the general hydrogen filling orifice 105 that is circular layout that adopts of circular hole passage injects.The design of pore opening, spacing, distributing position all has only a purpose, even hydrogen fully contacts with the F atom.So require generally that bore dia is little, spacing is little, be evenly distributed, hydrogen flow rate is very fast, and hydrogen can be joined in pipeline center's (line) position.

The main element of transmission window 103 place's Infrared Lens 104 is infrared (cover 2.5～3.8 mu m wavebands) eyeglass thoroughly; what generally select for use is the CaF2 eyeglass that is of a size of Φ 35 * 2.5 (mm); for avoiding containing of the corrosion of F atomic mixed gas stream, need contact top blast protection gas to eyeglass.In specific embodiment, protection gas is selected N for use ₂Position corresponding with Infrared Lens 104 on the transmission window 103 offers nitrogen filling orifice 106, nitrogen filling orifice 106 is communicated with gas channel 102 by two or more jet slits, this jet slit is parallel with minute surface, and nitrogen filling orifice 106 links to each other with nitrogen air supply source 107 by gas circuit.The air blowing mode for the minute surface parallel ring around being blown into, protection gas preferably can cover the surface of contact of minute surface and F atom air-flow.Saturating infrared eyeglass in the present embodiment; be blown into protection gas by the six roads slit parallel with eyeglass, the direct joint of part uses air seal glue to seal with O type seal with elastometic washer, the place of being threadedly engaged with; the lens protection lid adopts elastomeric material with the contact portion of minute surface, with screw pressing sealing.According to the concrete condition of system airflow path 10 2 to be measured, the infrared window matrix of design and system engages to be measured is installed in two lens carrier and eyeglass on the matrix then, constitutes a complete infrared window.

In the present embodiment, the inlet end of gas channel 102 links to each other by gas circuit and the F atom device 5 that dissociates, and endpiece links to each other with decontamination tower 6 by gas circuit.Like this, air-flow directly enters decontamination tower 6 behind titration apparatus 2, is extracted out by mechanical pump 601 then to be drained in the atmosphere.The medical soda lime of filling in the decontamination tower 601, in order in and waste gas in acidity and corrosive gas, to prevent to the corrosion of pumping fluid and the pollution of atmosphere.

In the present embodiment, fluorine source and assist gas air supply source 601, hydrogen air supply source 108, nitrogen air supply source 107 are sent into flow controller 7 and are carried out gas flow control, and then be passed in each device by airflow line by the gas cylinder air feed after the decompressor decompression.The D08-3D/2M type Flow Measurement Display Meter that flow controller 7 can adopt the Beijing Qixing Huachuang Electronics Co., Ltd to produce.

For the electric excitation HF chemical laser of selecting for use in the present embodiment, titration gas H ₂Itself be working gas, and generally all be the excessive state that is in during operate as normal, directly by laser instrument H ₂Gas channels originally injects; And utilize the concentration change of absorption spectroscopy detection reaction product HF, so the measuring process operate as normal of interference laser not; Can reach the purpose and the effect of noncontact on-line measurement after the employing demarcation scheme.For electric excitation DF chemical laser, full gas phase Chemical oxygen-iodine laser, siliceous semiconductor etching process equipment field only need distribute the part sample, also can reach the purpose and the effect of noncontact on-line measurement.

Claims (10)

1. the detection method of a F atomic concentration is characterized in that step is:

(1), in titration apparatus, feeds the mixed gas that contains the F atom, the both sides of titration apparatus are provided with Infrared Lens as transmission window, the probe light that the probe light source produces is after the semi-transparent semi-reflecting lens beam splitting, reflected light utilizes the infrared power detector to detect the power signal intensity of this moment as basal signal S successively by transmitting behind the Infrared Lens of two sides ₀

(2), in titration apparatus, feed gas H ₂, contain the mixed gas and the H of F atom ₂Rapid reaction F+H takes place ₂→ HF+H;

The probe light that the probe light source produces is after the semi-transparent semi-reflecting lens beam splitting, reflected light passes through an Infrared Lens rear portion beam split by the HF molecule absorption, remaining light transmits through the another side Infrared Lens, utilizes the infrared power detector to detect the power signal intensity of this moment as actual signal S ₁Transmitted light is directly incident on another infrared power detector, and the power signal intensity that detects this moment is as reference light signal S ₂

(3), by 1. obtain HF molecular absorption spectrum intensity A with following formula:

$A=\frac{S_0-S_1}{S_2}$ ①；

(4), increase progressively gas H ₂The flow that injects, the value of record HF molecular absorption spectrum intensity A is with gas H ₂The data of fluctuations in discharge are finished a titration process and are obtained HF absorption spectrum intensity with injecting H ₂The curve of fluctuations in discharge, flex point place, i.e. H in this curve ₂Pairing H during with the lucky complete reaction of F atom ₂Flow H (mol/s) equals to contain the flow of F atom in the mixed gas of F atom, in conjunction with the flow velocity v (m/s) of air-flow and the sectional area S (m of passage ²), utilize following formula 2. just can obtain F atomic concentration ρ (mol/m ³):

$\mathrm{\&rho;}=\frac{H}{v\&times;S}$ ②；

2. the detection method of F atomic concentration according to claim 1, it is characterized in that: the mixed gas that contains the F atom that repeatedly feeds variable concentrations, repetition above-mentioned steps (1), (2), (3), (4) can obtain a plurality of data points about F atomic concentration ρ and HF absorption spectrum intensity A, because 3. the relation of F atomic concentration ρ and HF absorption spectrum intensity A satisfies following formula, 3. through type can obtain the value of constant α; When actual measurement, only need in titration apparatus, to feed excessive gas H ₂, measure the value of a HF molecular absorption spectrum intensity A, 3. through type can obtain F atomic concentration ρ (mol/m again ³);

$\mathrm{\&rho;}=-\frac{1}{\mathrm{\&alpha;}}\ln A$ ③

In the formula: α=S φ (υ) L, the shape of the tested gas absorption spectrum line of linear function φ (υ) expression, S represents the spectral line absorption intensity, L be the single-frequency laser bundle the length by tested gas, v is the frequency of single-frequency laser bundle.

3. the detection method of F atomic concentration according to claim 1 and 2 is characterized in that: the distance of probe light to the two infrared power detector that described probe light source produces equates.

4. the pick-up unit of a F atomic concentration, it is characterized in that: it comprises titration apparatus (1), acquisition of signal acquisition system (2), probe light source (3) and semi-transparent semi-reflecting lens (4), described titration apparatus (1) comprises shell body (101), shell body (101) is hollow form and forms gas channel (102), shell body (101) is gone up symmetria bilateralis and is offered two transmission windows (103), transmission window (103) locates to be equiped with Infrared Lens (104), offer a plurality of hydrogen filling orifices (105) on the shell body (101), hydrogen filling orifice (105) links to each other with hydrogen air supply source (108) by pipeline; Described acquisition of signal acquisition system (2) comprises computing machine (201) and the first infrared power detector (202) that links to each other with computing machine (201) and the second infrared power detector (203), the probe light that probe light source (3) produces forms two-way light after the semi-transparent semi-reflecting lens beam splitting, by being transmitted to the first infrared power detector (202) behind the two sides Infrared Lens (104), transmitted light is directly incident on the second infrared power detector (203) to reflected light successively.

5. the pick-up unit of F atomic concentration according to claim 4, it is characterized in that: described transmission window (103) is gone up the position corresponding with Infrared Lens (104) and is offered nitrogen filling orifice (106), described nitrogen filling orifice (106) is communicated with gas channel (102) by two or more jet slits, this jet slit is parallel with minute surface, and nitrogen filling orifice (106) links to each other with nitrogen air supply source (107) by gas circuit.

6. according to the pick-up unit of claim 4 or 5 described F atomic concentrations, it is characterized in that: the inlet end of described gas channel (102) links to each other by gas circuit and the F atom device (5) that dissociates, and endpiece links to each other with decontamination tower (6) by gas circuit.

7. according to the pick-up unit of claim 4 or 5 described F atomic concentrations, it is characterized in that: described probe light source (3) adopts route selection electric excitation CW HF laser instrument.

8. the pick-up unit of F atomic concentration according to claim 6 is characterized in that: described probe light source (3) adopts route selection electric excitation CW HF laser instrument.

9. according to the pick-up unit of claim 4 or 5 described F atomic concentrations, it is characterized in that: the probe light that described probe light source (3) produces equates to the distance of the first infrared power detector (202) and the second infrared power detector (203).

10. the pick-up unit of F atomic concentration according to claim 8 is characterized in that: the probe light that described probe light source (3) produces equates to the distance of the first infrared power detector (202) and the second infrared power detector (203).

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