JP6240339B2 - Gas analyzer and gas processing apparatus - Google Patents

Description

  Embodiments described herein relate generally to a gas analyzer and a gas processing apparatus.

  Gas analyzers are used for various applications. It is important to obtain highly accurate analysis results stably.

JP2009-85872A

  Embodiments of the present invention provide a highly accurate gas analyzer and gas processing apparatus.

According to the embodiment of the present invention, the gas analyzer includes a cell unit, a light source unit, a detection unit, and a control unit. The light source unit includes a quantum cascade laser element that emits laser light due to transition between subbands, a first adjustment unit that coarsely adjusts the wavelength of the laser light using an external resonator, and a second adjustment unit that finely adjusts the wavelength. And having. A target substance containing a fluoride gas is introduced into the cell portion . Before Symbol detector detects the laser beam emitted from the cell portion after being absorbed in the fluoride gas introduced into the cell unit. The control unit calculates the concentration of the fluoride gas based on the light intensity of the laser light detected by the detection unit. The wavelength of the laser light is swept by the first adjustment unit within a coarse adjustment wavelength region within ± 5% of the peak wavelength of the fluoride gas absorption rate, and is further swept by the second adjustment unit. It is tuned to one of the peak wavelengths in a fine tuning wavelength region of ± 10 nm, and the coarse tuning wavelength region includes at least one wavelength of 7.9 μm, 8.5 μm, and 10.8 μm.

It is a schematic diagram which illustrates the gas analyzer which concerns on 1st Embodiment. It is a schematic diagram which illustrates the gas analyzer which concerns on 1st Embodiment. It is a schematic diagram which illustrates a part of gas analyzer which concerns on 1st Embodiment. It is a schematic diagram which illustrates a part of gas analyzer which concerns on 2nd Embodiment. It is a schematic diagram which illustrates a part of gas analyzer which concerns on 2nd Embodiment. It is a schematic diagram which illustrates some gas analyzers concerning 4th Embodiment. It is a schematic diagram which illustrates the gas analyzer which concerns on 5th Embodiment. It is a mimetic diagram which illustrates a part of gas analyzer concerning an embodiment. It is a mimetic diagram which illustrates a part of gas analyzer concerning an embodiment. FIG. 10A and FIG. 10B are schematic views illustrating a part of the gas analyzer according to the embodiment. FIG. 11A to FIG. 11C are schematic views illustrating a part of the gas analyzer according to the embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
It should be noted that the disclosure is merely an example, and those skilled in the art can easily correspond to appropriate changes while maintaining the gist of the invention, and are naturally included in the scope of the present invention. In addition, the drawings may be schematically represented with respect to the width, thickness, shape, and the like of each part in comparison with actual aspects for the sake of clarity of explanation, but are merely examples, and the interpretation of the present invention is not limited. It is not limited.
In addition, in the present specification and each drawing, elements similar to those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description may be omitted as appropriate.

(First embodiment)
FIG. 1 is a schematic view illustrating a gas analyzer according to the first embodiment.
As shown in FIG. 1, the gas analyzer 110 according to the present embodiment includes a cell unit 20, a light source unit 30, a detection unit 40, and a control unit 45. In this example, a housing 10w is further provided, and the cell unit 20, the light source unit 30, and the detection unit 40 are stored in the housing 10w.

  A sample gas 50 is introduced into the cell unit 20. For example, the cell unit 20 is provided with a cell 23, and a space 23 s is partitioned by the cell 23. The sample gas 50 is introduced into the space 23s. The sample gas 50 includes, for example, industrial exhaust gas. For example, a gas used for a process (for example, an etching process) in a manufacturing process of a semiconductor device is an exhaust gas. There is a detoxification device (gas treatment unit) that excludes dangerous substances from such exhaust gas. The exhaust gas after the hazardous substance is excluded by the abatement apparatus is included in the sample gas 50.

  The sample gas 50 includes a target substance 50a. The target substance 50a contains fluoride. The target substance 50a may include a plurality of substances (such as the first substance 51 and the second substance 52). Examples of the target substance will be described later.

  In this example, the cell unit 20 includes a first reflection unit 21 and a second reflection unit 22. The first reflection unit 21 and the second reflection unit 22 are reflective to the measurement light 30L. At least a part of the space 23 s is disposed between the first reflecting part 21 and the second reflecting part 22. The sample gas 50 is introduced into a space 23 s between the first reflecting part 21 and the second reflecting part 22.

  The light source unit 30 emits measurement light 30L. The measuring light 30L is incident on the sample gas 50 introduced into the space 23s. The wavelength of the measurement light 30L is variable. For example, the measurement light 30L includes a first light L1 having a first wavelength and a second light L2 having a second wavelength. The second wavelength is different from the first wavelength. These lights are incident on the sample gas 50.

  The measurement light 30L (the first light L1 and the second light L2) is reflected by the first reflecting part 21 and the second reflecting part 22, and is between the first reflecting part 21 and the second reflecting part 22 (space 23s). ) Multiple round trips. A part of the measurement light 30 </ b> L is absorbed by the target substance 50 a included in the sample gas 50. Of the measurement light 30L, a component having a wavelength peculiar to the substance is absorbed. The degree of absorption depends on the type and concentration of the target substance 50a.

  The detection unit 40 detects the intensity of the measurement light 30L (for example, the first light L1 and the second light L2) that has passed through the space 23s into which the sample gas 50 is introduced. That is, the measurement light 30L emitted from the cell unit 20 is detected by the detection unit.

  For the detection unit 40, an element having sensitivity in the infrared region is used. For the detection unit 40, for example, a thermopile or a semiconductor element (for example, MCT (HgCdTe)) is used. In the embodiment, the detection unit 40 is optional.

  The control unit 45 measures the concentration of the target substance 50a in the sample gas 50 based on the detection result of the measurement light 30L detected by the detection unit 40. An example of the operation of the control unit 45 will be described later.

  The light source unit 30 includes a laser element unit 30 a, a first adjustment unit 61, and a second adjustment unit 62. The laser element unit 30a emits measurement light 30L. As the laser element unit 30a, for example, an external resonator (EC) type quantum cascade laser (QCL) is used. An example of the laser element unit 30a will be described later.

  The 1st adjustment part 61 adjusts the wavelength of the laser element part 30a roughly. The second adjustment unit 62 finely adjusts the wavelength of the laser element unit 30a. For example, by adjusting the wavelength by the first adjustment unit 61, the center wavelength of the measurement light 30L is adjusted in a range of, for example, plus or minus 0.5 micrometers (μm). On the other hand, by the adjustment by the second adjustment unit 62, the wavelength of the measurement light 30L is adjusted in a range of, for example, plus or minus 10 nanometers (nm) with respect to the center wavelength. Examples of these adjustment units will be described later.

Hereinafter, usage examples of the gas analyzer 110 according to the embodiment will be described.
FIG. 2 is a schematic view illustrating the gas analyzer according to the first embodiment.
As shown in FIG. 2, the gas analyzer 110 is attached to an exhaust treatment device 320 (for example, an abatement device). The exhaust treatment device 320 treats (for example, removes) the gas discharged from the industrial treatment device. Industrial processing apparatuses are, for example, etching apparatuses 411 and 412. The gas analyzer 110 and the exhaust treatment device 320 are included in the gas treatment device 310.

  Exhaust gas discharged from the etching apparatuses 411 and 412 is supplied to the exhaust processing apparatus 320. In the exhaust treatment device 320, for example, processing such as exclusion of dangerous substances is performed. The exhaust gas processed by the exhaust processing device 320 is supplied to the gas analyzer 110.

  Industrial equipment has been moving for a long time. The target substance 50a contained in the gas is detected over a long period of time during the movable time. The amount of gas discharged from the exhaust treatment device 320 and the type of gas vary. The industrial gas analyzer has a special problem of continuously measuring the target substance 50a over a long period of time. And it is required to detect stably and with high accuracy.

  In order to continuously analyze the concentration of a plurality of substances contained in the sample gas 50, it is required to quickly match the wavelength of the measurement light 30L with the absorption wavelength of each substance. The wavelength of the measurement light 30L is also required to be set with high accuracy.

  On the other hand, the gas analyzer 110 according to the present embodiment is provided with a first adjustment unit 61 that roughly adjusts the wavelength. Thereby, the wavelength of the measurement light 30L can be quickly adjusted to the target absorption wavelength. Further, a second adjustment unit 62 that finely adjusts the wavelength is provided. Thereby, the wavelength of the measurement light 30L can be adjusted with high accuracy.

  Thereby, the density | concentration of the target substance 50a in the sample gas 50 can be measured continuously and stably with high accuracy. Even when the concentration of the target substance 50a varies greatly, stable and highly accurate detection is possible.

  For example, the concentration of a plurality of substances can be quickly analyzed by adjustment by the first adjustment unit 61. Thereby, continuous highly accurate detection becomes possible. The concentration of the substance can be analyzed with high accuracy by adjustment by the second adjustment unit 62.

The target substance 50a contained in the sample gas 50 is, for example, fluoride. The target substance 50a includes, for example, at least one of CF ₄ , C ₂ F ₆ , C ₃ F ₈ , c-C ₄ F ₈ , CHF ₃ , NF ₃ and SF ₆ . Such a substance is a greenhouse gas. It is particularly desirable to continuously and stably measure such gas emissions. It is effective to apply the embodiment to such applications.

The concentration of the target substance 50a in the sample gas 50 is, for example, 500 ppm or less. In the embodiment, the concentration of the target substance 50a is detected with an accuracy of 10 ppm or less, for example. Thereby, management of global warming gas can be carried out effectively. Management of harmful gas emissions can be carried out effectively. The harmful gas is, for example, CF ⁺ , CF2 ⁺ or CF3 ⁺ .

FIG. 3 is a schematic view illustrating a part of the gas analyzer according to the first embodiment.
FIG. 3 is a schematic view illustrating a part of the light source unit 30.
As shown in FIG. 3, in this example, a diffraction grating 65 is used as the first adjustment unit 61. The light emitted from the laser element unit 30a is incident on the diffraction grating 65 (first adjusting unit 61). The diffraction grating 65 forms a resonator together with the laser element unit 30a. According to the angle of the diffraction grating 65, the resonance length of the resonator changes. Thereby, the wavelength of the measurement light 30L can be adjusted roughly.

  In this example, a temperature control unit 62 a and a power source 62 b are used as the second adjustment unit 62. The temperature control unit 62a adjusts the temperature of the laser element unit 30a. The wavelength of the light emitted from the laser element unit 30a depends on the temperature. By adjusting the temperature of the laser element portion 30a, the wavelength can be adjusted with high accuracy. On the other hand, the power source 62b supplies a current to the laser element unit 30a. The wavelength of the light emitted from the laser element unit 30a depends on the current. The wavelength can be adjusted with high accuracy by adjusting the current. Thus, as the second adjustment unit 62, the laser driving unit 62r that adjusts the temperature of the laser element unit 30a and the current flowing through the laser element unit can be used.

(Second Embodiment)
FIG. 4 is a schematic view illustrating a part of the gas analyzer according to the second embodiment.
As shown in FIG. 4, in the gas analyzer 120, the laser element unit 30a is provided with a first laser element Ls1, a second laser element Ls2, and a third laser element Ls3. The first laser element Ls1 emits the first light L1 having the first wavelength. The second laser element Ls2 emits the second light L2 having the second wavelength. The third laser element Ls3 emits the third light L3 having the third wavelength. These lights are included in the measurement light 30L.

  The first wavelength is, for example, about 7.9 μm (such as 7.9 μm plus or minus 5%). The second wavelength is, for example, about 8.5 μm (such as 8.5 μm plus or minus 5%). The third wavelength is, for example, about 10.8 μm (10.8 μm plus or minus 5%, etc.). In embodiments, these wavelengths are arbitrary. It is determined appropriately according to the target target substance 50a.

  In this example, a switching unit 66 is used as the first adjustment unit 61. The switching unit 66 switches whether the first light L1 is incident on or not incident on the space 23s. The switching unit 66 switches whether the second light L2 is incident on or not incident on the space 23s. The switching unit 66 switches whether the third light L3 is incident or not incident on the space 23s. For example, the switching unit 66 selectively emits light from each laser element. The light may be continuously emitted from the laser element, and the light blocking or transmission may be controlled by the switching unit 66. An optical switch or the like may be used as the switching unit 66. A galvanometer mirror or the like may be used as the switching unit 66.

  The wavelength of the measurement light 30 </ b> L is roughly adjusted to any one of the first wavelength, the second wavelength, and the third wavelength by the first adjustment unit 61.

  As the second adjustment unit 62, a laser driving unit 62r is used. The laser driver 62r adjusts at least one of the temperature of the first laser element Ls1 and the current flowing through the first laser element Ls1. The laser driver 62r adjusts at least one of the temperature of the second laser element Ls2 and the current flowing through the second laser element Ls2. The laser driver 62r adjusts at least one of the temperature of the third laser element Ls3 and the current flowing through the third laser element Ls3. Thereby, the wavelength of the measurement light 30L is finely adjusted.

  In this example, each of the plurality of laser elements is provided in each of the plurality of laser elements. In the embodiment, one laser driving unit may be connected to a plurality of laser elements. In this case, for example, a switch (for example, a power transistor) is provided in one laser driving unit, and the laser element that supplies current is switched.

  In this example, an optical element is provided to cause the first light L1 to the third light L3 to enter the cell unit 20 (space 23s). In this example, a first optical element M1 and a second optical element M2 are provided.

  The second optical element M2 reflects the first light L1, reflects the second light L2, and transmits the third light L3. Thereby, these lights can be incident on the space 23s through the same optical path. A third optical element M3 may be provided instead of the second optical element M2. The third optical element M3 transmits the first light L1, transmits the second light L2, and reflects the third light L3. At this time, the arrangement of the first laser element Ls1 to the third laser element Ls3 is changed according to the third optical element M3.

  Such second optical element M2 and third optical element M3 are effective, for example, when the first wavelength is relatively close to the second wavelength and the difference between these wavelengths and the third wavelength is large. That is, in this example, the absolute value of the difference between the third wavelength and the first wavelength is larger than the absolute value of the difference between the first wavelength and the second wavelength. The absolute value of the difference between the third wavelength and the second wavelength is larger than the absolute value of the difference between the first wavelength and the second wavelength.

  Furthermore, in such a wavelength relationship, transmission and non-transmission of the first light L1 and the second light L2 may be controlled using polarized light. For example, the polarization direction of the first light L1 is different from the polarization direction of the second light L2. At this time, the first optical element M1 transmits one of the first light L1 and the second light L2, and reflects the other of the first light L1 and the second light L2. That is, transmission and non-transmission change according to the polarization.

  For example, the first light L1 is p-polarized light and the second light L2 is s-polarized light. At this time, the first optical element M1 transmits p-polarized light and reflects s-polarized light. Thereby, the first light L2 and the second light L2 can be incident on the space 23s through substantially the same optical path.

  The first light L1 is s-polarized light, and the second light L2 is p-polarized light. At this time, the first optical element M1 transmits s-polarized light and reflects p-polarized light. Thereby, the first light L2 and the second light L2 can be incident on the space 23s through substantially the same optical path. High-precision measurement is possible.

  For example, the first light L1 to the third light L3 may be sequentially incident on the space 23s. For example, the first light L1 enters the space 23s in the first period. In the second period after the first period, the second light L2 enters the space 23s. In the third period after the second period, the third light L3 enters the space 23s. The relationship between the lengths of these wavelengths at this time is arbitrary. In this way, the light may be switched in a time division manner.

  Further, the order of incidence in the space 23s may be switched from light having low transmittance to light having high transmittance in accordance with the target substance 50a, for example. Thereby, the saturation in the detection part 40 can be suppressed.

  For example, the transmittance of the target substance 50a for the first wavelength is lower than the transmittance of the target substance 50a for the second wavelength, and the transmittance of the target substance 50a for the second wavelength is the transmittance of the target substance 50a for the third wavelength. Lower than. At this time, the first light L1, the second light L2, and the third light L3 are sequentially incident on the space 23s. Thereby, the saturation in the detection part 40 can be suppressed. Thereby, high accuracy is obtained in detection.

  Furthermore, when light having a high transmittance is incident on the space 23s and then incident on the space 23s having a low transmittance, a predetermined waiting time may be inserted therebetween. Thereby, the saturation in the detection part 40 can be suppressed.

  In the embodiment, two or more of the first light L1 to the third light L3 may be incident on the space 23s within the same period.

(Third embodiment)
FIG. 5 is a schematic view illustrating a part of the gas analyzer according to the second embodiment.
As shown in FIG. 5, also in the gas analyzer 130 according to the present embodiment, the light source unit 30 is provided with a laser element unit 30 a, a first adjustment unit 61, and a second adjustment unit 62. The laser element unit 30a includes a first laser element Ls1, a second laser element Ls2, and a third laser element Ls3. The first wavelength of the first light L1 emitted from the first laser element Ls1 is, for example, about 7.9 μm. The second wavelength of the second light L2 emitted from the second laser element Ls2 is, for example, about 8.5 μm. The third wavelength of the third light L3 emitted from the third laser element Ls3 is, for example, about 10.8 μm. In embodiments, these wavelengths are arbitrary. It is determined appropriately according to the target target substance 50a.

  In this example, a switching unit 66 is provided as the first adjustment unit 61. As the switching unit 66, a mirror having a variable angle is used. The change in the angle of the mirror controls the incidence of light into the space 23s. For example, the first light L1 enters the space 23s when the angle of the mirror is in the first state. When the angle of the mirror is in the second state, the second light L2 enters the space 23s. When the angle of the mirror is in the third state, the third light L3 enters the space 23s. This figure illustrates the second state. Thus, the wavelength of the measurement light 30L is roughly adjusted to the first wavelength, the second wavelength, the third wavelength, and the like by the operation of the mirror.

  As the second adjustment unit 62, a laser drive unit 62r is provided. The laser driver 62r controls at least one of the temperature and current of each of these laser elements. Thereby, the wavelength of the measurement light 30L is finely adjusted.

(Fourth embodiment)
FIG. 6 is a schematic view illustrating a part of the gas analyzer according to the fourth embodiment.
As shown in FIG. 6, also in the gas analyzer 140 according to the present embodiment, the light source unit 30 is provided with a laser element unit 30 a, a first adjustment unit 61, and a second adjustment unit 62. In this example, the laser element unit 30a includes a first laser element Ls1 and a second laser element Ls2. A third laser element Ls3 may be further provided. Also in this example, the switching unit 66 is used as the first adjustment unit 61, and the laser driving unit 62 r is used as the second adjustment unit 62.

  In this example, the angle at which the first light L1 emitted from the first laser element Ls1 enters the cell part 20 (space 23s) is the same as the angle at which the second light L2 emitted from the second laser element Ls2 is the cell part 20 (space 23s). It is different from the incident angle. Thereby, different optical path lengths are provided in the measurement light 30L.

  That is, the measurement light 30 </ b> L (the first light L <b> 1 and the second light L <b> 2, etc.) is reflected by the first reflection unit 21 and the second reflection unit 22 provided in the cell unit 20 and reaches the detection unit 40.

  At this time, since the angle of incidence on the cell unit 20 (space 23s) is different between the first light L1 and the second light L2, these lights are emitted to the outside of the cell unit 20 at different times and are detected by the detection unit. 40 is reached. For example, the first light path length from when the first light L1 is reflected by the first reflecting portion 21 and the second reflecting portion 22 to reach the detecting portion 40 is equal to the second light L2 being the first reflecting portion 21 and the second reflecting length. This is different from the second optical path length that is reflected by the reflection unit 22 and reaches the detection unit 40. Thus, the optical path length is changed according to the light.

  For example, the absorption coefficient varies depending on the type of the target substance 50a, and the amount of absorption in the space 23s varies. The amount of absorption varies depending on the concentration of the target substance 50a. On the other hand, there is a predetermined range in the dynamic range of light intensity detection in the detection unit 40. The light intensity (amount of absorption) of light incident on the detection unit 40 is set to an appropriate range. Thereby, the detection accuracy in the detection unit 40 can be maintained high.

  In the present embodiment, the amount of light absorption is adjusted by changing the optical path length according to the state of the sample gas 50, and the measurement light 30 </ b> L having an appropriate intensity is incident on the detection unit 40. Thereby, highly accurate detection becomes possible.

  For example, the optical path length when the absorption coefficient is high is made shorter than the optical path length when the absorption coefficient is low. For example, the optical path length when the concentration of the target substance 50a in the sample gas 50 is high is made shorter than the optical path length when the concentration is low.

  For example, when there is a difference in absorption rate, the following is performed. An example in which the target substance 50a includes a first substance 51 and a second substance 52 different from the first substance 51 will be described. It is assumed that the first wavelength of the first light L1 is the peak wavelength of the rescue rate (first absorption rate) of the first substance 51. The second wavelength of the second light L2 is assumed to be the peak wavelength of the absorption rate (second absorption rate) of the second substance 52. The first absorption rate is assumed to be higher than the second absorption rate. At this time, the first optical path length is made shorter than the second optical path length. For example, the incident angle of the first light L1 is made larger than the incident angle of the second light L2.

  For example, when there is a difference in density, the following is performed. Also in this case, it is assumed that the first wavelength is the peak wavelength of the first absorption rate of the first substance 51 and the second wavelength is the peak wavelength of the second absorption rate of the second substance. Then, it is assumed that the concentration of the first substance 51 in the sample gas 50 is higher than the concentration of the second substance 52 in the sample gas 50. At this time, the first optical path length is made shorter than the second optical path length.

  Thus, the optical path length is set so that appropriate detection sensitivity can be obtained according to the type or concentration of the substance. Thereby, it is possible to obtain the concentration with high accuracy for each of the plurality of substances.

(Fifth embodiment)
FIG. 7 is a schematic view illustrating a gas analyzer according to the fifth embodiment.
FIG. 7 is a graph illustrating characteristics of the gas analyzer according to this embodiment. The horizontal axis is the wavelength λ, and the vertical axis is the intensity Int of the measurement light 30L detected by the detector 40. In this example, the first substance 51 is CF ₄ and the second substance 52 is C ₂ F ₆ . In this example, the wavelength in the range of about 8.7 μm to 9.0 μm is illustrated.

  In this wavelength range, as the wavelength λ becomes longer, the light intensity Int in the first substance 51 increases. On the other hand, when the wavelength λ becomes shorter in this wavelength range, the light intensity Int in the second substance 52 decreases. The slope of the change of the light intensity Int in the first substance 51 with respect to the wavelength λ is positive. The gradient of the change of the light intensity Int with respect to the wavelength λ in the second substance 52 is negative. A wavelength at which the gradient of the change has a reverse polarity is used as the wavelength of the measurement light 30L.

  That is, when the wavelength of the measurement light 30L is increased, the absorption rate of the first substance 51 decreases and the absorption rate of the second substance 52 increases.

  Thus, at a specific wavelength (in this example, about 8.2 μm), the absorption characteristics of a plurality of substances having different directions of change intersect with the wavelength change. The center wavelength of the measurement light 30L is set to such a wavelength. Thereby, the concentration of a plurality of substances can be detected with high accuracy by changing the wavelength of the measurement light 30L and detecting the degree of absorption.

(Sixth embodiment)
The present embodiment relates to a gas processing apparatus. As illustrated in FIG. 2, the gas processing device 310 includes a gas analysis device 110 and an exhaust processing device 320. The exhaust treatment device 320 supplies the sample gas 50 to the gas analyzer 110. As the gas analyzer, any gas analyzer according to the above embodiment and a modified gas analyzer may be used. The gas processing apparatus 310 according to the present embodiment can perform highly accurate analysis and can perform highly accurate gas processing. Stable gas treatment can be carried out continuously.

Hereinafter, an example of the light source unit 30 applicable to the embodiment will be described.
FIG. 8 is a schematic view illustrating a part of the gas analyzer according to the embodiment.
As illustrated in FIG. 8, the light source unit 30 (laser element unit 30a) includes a semiconductor light emitting element 30aL and a wavelength control unit 30aC. As will be described later, the semiconductor light emitting element 30aL emits emitted light by energy relaxation of electrons in subbands of a plurality of quantum wells, for example. For example, the wavelength control unit 30aC adjusts the wavelength of the emitted light to generate the first light L1 and the second light L2.

  For example, the wavelength control unit 30aC includes a first adjustment mechanism. The first adjustment mechanism shifts the wavelength of the infrared laser light emitted from the semiconductor light emitting element 30aL into the absorption spectrum of one kind of gas among the plurality of gases included in the sample gas 50. The wavelength control unit 30aC may further include a second adjustment mechanism. For example, the second adjustment mechanism adjusts the wavelength by shifting the wavelength in the absorption spectrum of one kind of gas.

  For example, the first adjustment mechanism includes a diffraction grating 71. The diffraction grating 71 is provided so as to intersect with the optical axis 31Lx of the semiconductor light emitting element 30aL. The diffraction grating 71 forms an external resonator. The incident angle of the infrared laser light to the diffraction grating 71 is changed according to the absorption spectra of the plurality of substances contained in the sample gas 50. The incident angle is changed to, for example, angles β1 to β4. Thereby, the wavelength of infrared laser light is changed.

  For example, a stepping motor 99 and a drive control unit 98 are provided. The drive control unit 98 controls (drives) the stepping motor 99. The diffraction grating 71 is rotationally controlled by the stepping motor 99 and the drive control unit 98 around an axis that intersects the optical axis 31Lx.

  It is preferable to provide an antireflection coating film AR on the end face of the semiconductor light emitting element 30aL on the diffraction grating 71 side. A partially reflective coating film PR (Perfect Reflection) may be provided. The semiconductor light emitting element 30aL is disposed between the partial reflection coating film PR and the antireflection coating film AR. An external resonator is formed between the partially reflective coating film PR and the diffraction grating 71.

  In the embodiment, the wavelength may be further accurately adjusted by the second adjustment mechanism. For example, the drive part 30b (refer FIG. 1) can be used as a 2nd adjustment mechanism. The drive unit 30b changes at least one of the operating current value and the duty of the semiconductor light emitting element 30aL. The second control unit 90 may be used as the second adjustment mechanism. For example, the second control unit 90 changes the temperature of the semiconductor light emitting element 30aL. For example, a Peltier element or the like is used as the second control unit 90. For example, a stress generating element may be used as the second adjustment mechanism. The stress generating element changes the external resonator length. As the stress generating element, for example, a piezo element or the like can be used.

FIG. 9 is a schematic view illustrating a part of the gas analyzer according to the embodiment.
FIG. 9 shows another example of the laser element unit 30a.
In this example, a diffraction grating 71a is used as the first adjustment mechanism. The diffraction grating 71a moves in an XY plane that intersects the optical axis 31Lx of the semiconductor light emitting element 30aL at a predetermined incident angle γ. The diffraction grating 71 a is moved by, for example, the stepping motor 99 and the drive control unit 98. An external resonator (EC) is formed by the diffraction grating 71a and the partially reflective coating film PR of the semiconductor light emitting element 30aL. The measurement light 30 </ b> L emitted from the partial reflection coating film PR enters the cell unit 20.

FIG. 10A and FIG. 10B are schematic views illustrating a part of the gas analyzer according to the embodiment.
These drawings are schematic plan views showing examples of the diffraction grating 71a.
As illustrated in FIGS. 10A and 10B, the diffraction grating 71 has a plurality of regions. In a plurality of regions, the pitch of the grating is different.

  In the example shown in FIG. 10A, the pitch of the grating is different along the X direction. A plurality of regions having different pitches are provided. The resonance wavelength is region rg2> region rg1> region rg3. For example, the wavelength can be adjusted by moving in the X direction.

  In the example shown in FIG. 10B, the resonance wavelengths are region rg5> region rg6> region rg7> region rg4. For example, the diffraction grating 71a is moved along the arrow direction SD illustrated in FIG. Thereby, a wavelength can be adjusted. The cross-sectional shape of the diffraction grating 71a may be asymmetric.

FIG. 11A to FIG. 11C are schematic views illustrating a part of the gas analyzer according to the embodiment.
FIG. 11A is a schematic perspective view. FIG. 11B is a cross-sectional view taken along line A1-A2 of FIG. FIG. 11C is a schematic view illustrating the operation of the light source unit 30.
In this example, a semiconductor light emitting element 30 aL is used as the light source unit 30. A laser is used as the semiconductor light emitting element 30aL. In this example, a quantum cascade laser is used.

  As shown in FIG. 11A, the semiconductor light emitting element 30aL includes a substrate 35, a stacked body 31, a first electrode 34a, a second electrode 34b, a dielectric layer 32 (first dielectric layer), and And an insulating layer 33 (second dielectric layer).

  A substrate 35 is provided between the first electrode 34a and the second electrode 34b. The substrate 35 includes a first portion 35a, a second portion 35b, and a third portion 35c. These parts are arranged in one plane. This plane intersects (for example, parallel) with respect to the direction from the first electrode 34a to the second electrode 34b. A third portion 35c is disposed between the first portion 35a and the second portion 35b.

  The stacked body 31 is provided between the third portion 35c and the first electrode 34a. The dielectric layer 32 is provided between the first portion 35a and the first electrode 34a and between the second portion 35b and the first electrode 34a. An insulating layer 33 is provided between the dielectric layer 32 and the first electrode 34a.

  The stacked body 31 has a stripe shape. The stacked body 31 functions as a ridge waveguide RG. The two end surfaces of the ridge waveguide RG become mirror surfaces. The light 31L emitted from the stacked body 31 is emitted from the end face (light emission surface). The light 31L is an infrared laser beam. The optical axis 31Lx of the light 31L is along the extending direction of the ridge waveguide RG.

  As illustrated in FIG. 11B, the stacked body 31 includes, for example, a first cladding layer 31a, a first guide layer 31b, an active layer 31c, a second guide layer 31d, and a second cladding layer 31e. ,including. These layers are arranged in this order along the direction from the substrate 35 toward the first electrode 34a. Each of the refractive index of the first cladding layer 31a and the refractive index of the second cladding layer 31e is based on the refractive index of the first guide layer 31b, the refractive index of the active layer 31c, and the refractive index of the second guide layer 31d. Is also low. The light 31L generated in the active layer 31c is confined in the stacked body 31. The first guide layer 31b and the first cladding layer 31a may be collectively referred to as a cladding layer. The second guide layer 31d and the second cladding layer 31e may be collectively referred to as a cladding layer.

  The stacked body 31 has a first side surface 31sa and a second side surface 31sb that are perpendicular to the optical axis 31Lx. A distance 31w (width) between the first side surface 31sa and the second side surface 31sb is, for example, not less than 5 μm and not more than 20 μm. Thereby, for example, the control in the horizontal / horizontal mode is facilitated, and the output is easily improved. If the distance 31w is excessively long, a high-order mode is likely to occur in the horizontal and transverse mode, and the output is difficult to increase.

  The refractive index of the dielectric layer 32 is lower than the refractive index of the active layer 31c. Thereby, the ridge waveguide RG is formed by the dielectric layer 32 along the optical axis 31Lx.

  As shown in FIG. 11C, the active layer 31c has, for example, a cascade structure. In the cascade structure, for example, the first regions r1 and the second regions r2 are alternately stacked. The unit structure r3 includes a first region r1 and a second region r2. A plurality of unit structures r3 are provided.

  For example, a first barrier layer BL1 and a first quantum well layer WL1 are provided in the first region r1. A second barrier layer BL2 is provided in the second region r2. For example, the third barrier layer BL3 and the second quantum well layer WL2 are provided in another first region r1a. The fourth barrier layer BL4 is provided in another second region r2a.

  In the first region r1, an intersubband optical transition of the first quantum well layer WL1 occurs. Thereby, for example, light 31La having a wavelength of 3 μm or more and 18 μm or less is emitted.

  In the second region r2, the energy of carriers c1 (for example, electrons) injected from the first region r1 can be relaxed.

  In the quantum well layer (for example, the first quantum well layer WL1), the well width WLt is, for example, 5 nm or less. When the well width WLt is so narrow, the energy levels are discrete, and for example, the first subband WLa (high level Lu) and the second subband WLb (low level Ll) are generated. Carriers c1 injected from the first barrier layer BL1 are effectively confined in the first quantum well layer WL1.

  When the carrier c1 transitions from the high level Lu to the low level Ll, light 31La corresponding to the energy difference (difference between the high level Lu and the low level Ll) is emitted. That is, an optical transition occurs.

  Similarly, light 31Lb is emitted from the second quantum well layer WL2 in another first region r1a.

  In the embodiment, the quantum well layer may include a plurality of wells with overlapping wave functions. The high levels Lu of the plurality of quantum well layers may be the same. The low levels Ll of the plurality of quantum well layers may be the same as each other.

  For example, the intersubband optical transition occurs in either the conduction band or the valence band. For example, recombination of holes and electrons by a pn junction is not necessary. For example, an optical transition is caused by either the hole or electron carrier c1, and light is emitted.

  In the active layer 31c, for example, the voltage applied between the first electrode 34a and the second electrode 34b causes the carrier c1 (for example, electrons) to be quantum via the barrier layer (for example, the first barrier layer BL1). Implanted into the well layer (for example, the first quantum well layer WL1). This causes an intersubband optical transition.

  The second region r2 has, for example, a plurality of subbands. The subband is, for example, a miniband. The energy difference in the subband is small. The subband is preferably close to a continuous energy band. As a result, the energy of the carrier c1 (electrons) is relaxed.

  In the second region r2, for example, light (for example, infrared rays having a wavelength of 3 μm to 18 μm) is not substantially emitted. The carriers c1 (electrons) of the low level L1 in the first region r1 pass through the second barrier layer BL2 and are injected into the second region r2 and relaxed. The carrier c1 is injected into another first region r1a that is cascade-connected. An optical transition occurs in this first region r1a.

  In the cascade structure, an optical transition occurs in each of the plurality of unit structures r3. This makes it easy to obtain a high light output in the entire active layer 31c.

  As described above, the light source unit 30 includes the semiconductor light emitting element 30aL. The semiconductor light emitting device 30aL emits the measurement light 30L by energy relaxation of electrons in subbands of a plurality of quantum wells (for example, the first quantum well layer WL1 and the second quantum well layer WL2).

For example, GaAs is used for the quantum well layers (for example, the first quantum well layer WL1 and the second quantum well layer WL2). For example, Al _x Ga _1-x As (0 <x <1) is used for the barrier layer (for example, the first to fourth barrier layers BL1 to BL4, etc.), for example. At this time, for example, when GaAs is used as the substrate 35, good lattice matching is obtained in the quantum well layer and the barrier layer.

The first cladding layer 31a and the second cladding layer 31e include, for example, Si as an n-type impurity. The impurity concentration in these layers is, for example, 1 × 10 ¹⁸ cm ⁻³ or more and 1 × 10 ²⁰ cm ⁻³ or less (for example, about 6 × 10 ¹⁸ cm ⁻³ ). The thickness of each of these layers is, for example, not less than 0.5 μm and not more than 2 μm (for example, about 1 μm).

The first guide layer 31b and the second guide layer 31d include, for example, Si as an n-type impurity. The impurity concentration in these layers is, for example, 1 × 10 ¹⁶ cm ⁻³ or more and 1 × 10 ¹⁷ cm ⁻³ or less (for example, about 4 × 10 ¹⁶ cm ⁻³ ). The thickness of each of these layers is, for example, 2 μm or more and 5 μm or less (for example, 3.5 μm).

  The distance 31w (the width of the stacked body 31, that is, the width of the active layer 31c) is, for example, 5 μm or more and 20 μm or less (for example, about 14 μm).

  The length of the ridge waveguide RG is, for example, 1 mm or more and 5 mm or less (for example, about 3 mm). The semiconductor light emitting element 30aL operates at an operating voltage of 10 V or less, for example. The current consumption is lower than that of a carbon dioxide laser device or the like. Thereby, operation with low power consumption is possible.

  According to the embodiment, a highly accurate gas analyzer and gas processing apparatus can be provided.

  In the present specification, “vertical” and “parallel” include not only strictly vertical and strictly parallel, but also include, for example, variations in the manufacturing process, and may be substantially vertical and substantially parallel. It ’s fine.

The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, a cell unit, a light source unit, a detection unit, a control unit, a laser element unit, a laser element, a first adjustment unit, a second adjustment unit, a laser drive unit, a switching unit, an optical element and a mirror included in the gas analyzer, and With respect to the specific configuration of each element such as the exhaust treatment device included in the gas treatment device, those skilled in the art can implement the present invention in the same manner by selecting appropriately from a known range, and the same effect can be obtained. As long as it is within the scope of the present invention.
Moreover, what combined any two or more elements of each specific example in the technically possible range is also included in the scope of the present invention as long as the gist of the present invention is included.

  All gas analyzers and gas processing apparatuses that can be implemented by those skilled in the art based on the gas analyzers and gas processing apparatuses described above as embodiments of the present invention also include the gist of the present invention. As long as it belongs to the scope of the present invention.

  In the scope of the idea of the present invention, those skilled in the art can conceive various changes and modifications, and it is understood that these changes and modifications also belong to the scope of the present invention.

  For example, those in which the person skilled in the art appropriately added, deleted, or changed the design of the above-described embodiments, or those in which the process was added, omitted, or changed the conditions are also included in the gist of the present invention. As long as it is provided, it is included in the scope of the present invention.

  In addition, other functions and effects brought about by the aspects described in the present embodiment, which are apparent from the description of the present specification, or can be appropriately conceived by those skilled in the art, are naturally understood to be brought by the present invention. .

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

Claims (7)

A light source comprising: a quantum cascade laser element that emits laser light by intersubband transition; a first adjustment unit that coarsely adjusts the wavelength of the laser light using an external resonator; and a second adjustment unit that finely adjusts the wavelength And
A cell part into which a sample gas containing fluoride gas is introduced;
A detection unit for detecting the laser beam emitted from the cell unit after being absorbed by the fluoride gas introduced into the cell unit;
A control unit that calculates the concentration of the fluoride gas contained in the sample gas based on the light intensity of the laser beam detected by the detection unit;
With
The wavelength of the laser light is swept by the first adjustment unit within a coarse adjustment wavelength region within ± 5% of the peak wavelength of the fluoride gas absorption rate, and is further swept by the second adjustment unit. Tuned to one of the peak wavelengths in a fine tuning wavelength region of ± 10 nm,
The gas analysis apparatus , wherein the coarse adjustment wavelength region includes at least one wavelength of 7.9 μm, 8.5 μm, and 10.8 μm . The gas analyzer according to claim 1, wherein the light source unit emits a plurality of laser beams having different rough adjustment wavelength regions. In the coarse adjustment wavelength region corresponding to one of the peak wavelengths of the fluoride gas, a slope with respect to the wavelength of the absorptivity of the fluoride gas, and a slope with respect to a wavelength of the absorptivity of fluoride gases having different compositions The gas analyzer according to claim 1, wherein a wavelength region having a reverse polarity is included. The first adjustment unit includes a diffraction grating that forms the external resonator together with the quantum cascade laser element,
The gas analyzer according to claim 1, wherein the second adjustment unit includes a laser driving unit that adjusts a temperature or a current of the quantum cascade laser element. The fluoride _{gas, CF 4, C 2 F 6} , C 3 F 8, C 4 F 8, CHF 3, according to any one of claims 1 to 4 comprising at least one of NF ₃ and SF ₆ Gas analyzer. The gas analyzer according to claim 1, wherein a concentration of the fluoride gas in the sample gas is 500 ppm or less. A gas analyzer according to any one of claims 1 to 6 ;
An exhaust treatment device for discharging the sample gas toward the gas analyzer;
A gas processing apparatus comprising:

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