Concentration measuring device

Abstract

A concentration measurement device 20, for measuring the concentration of a gas flowing through a confluence block 14 to which a plurality of gas supply lines are connected, is provided with a light source 40 for generating light which is made incident on a flow channel formed in the confluence block, a photodetector 44 for receiving light exciting from the flow channel, and a computation control circuit 46 for determining the concentration of a gas flowing through the flow channel on the basis of the output of the photodetector, translucent incidence windows 26, 23 for causing light from the light source to be incident on the flow channel, and / or translucent emission windows 28, 23 for emitting light transmitted through the flow channel being sealed and fixed to the confluence block 14.

Description

Technical Field

[0001] The present invention relates to a concentration measuring device, and more particularly to a concentration measuring device that detects the concentration of a gas based on the absorbance of light transmitted through the gas.

Background Art

[0002] A gas supply system used in a semiconductor manufacturing apparatus is configured to supply various types of gases to a process chamber by switching through a flow rate controller provided for each gas type. The types of gases used in semiconductor manufacturing tend to increase year by year, and the number of gas supply lines and the number of fluid control devices used have also increased.

[0003] As a means for forming a plurality of gas supply lines, an integrated gas supply system IGS (registered trademark) developed by the applicant of the present application is widely used. In the integrated gas supply system, each gas supply line is formed by arranging and fixing a flow path block (joint block), an on-off valve, a fluid controller, etc. on a base plate.

[0004] In addition, in the integrated gas supply system, a configuration in which the outlet side of each supply line is connected to a common manifold block (confluence block) is known (for example, Patent Document 1). The outlet of the manifold block connected to each line is connected to a process chamber via a flow path, and any gas can be supplied by controlling the on-off valve provided in each supply line.

[0005] On the other hand, a concentration measuring device (in-line type concentration measuring device) configured to measure the gas concentration incorporated in a gas supply line is known. Patent Document 2 discloses a concentration measuring device that irradiates light of a predetermined wavelength from a light source through a light incident window to a measurement cell incorporated as a part of a flow path, and measures the absorbance from the transmitted light that has passed through the measurement cell. From the measured absorbance, the concentration of the fluid can be obtained according to the Lambert-Beer law or the like.

Prior Art Documents

Patent Document

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] Conventional in-line type concentration measurement devices were separately arranged downstream of the integrated gas supply system, more specifically, in the middle of the flow path between the integrated gas supply system and the process chamber. For example, a reflection type concentration measurement device using a vertical measurement cell (a type in which the flow path in the measurement cell is orthogonal to the line flow path) described in Patent Document 2 has a relatively compact design, and since the mounting part of the optical system is concentrated at the upper end of the measurement cell, it is relatively easy to install even in the middle of the flow path.

[0008] However, although conventional concentration measurement devices have been miniaturized, it is necessary to secure space for installation. Therefore, for recent semiconductor manufacturing devices to which various devices are connected and there is almost no surplus space around them, there has been a demand for an in-line type concentration measurement device that can be incorporated into the gas supply system and appropriately measure the gas concentration without requiring as much installation space as possible.

[0009] The present invention has been made in view of the above problems, and its main object is to provide a concentration measurement device incorporated into a gas supply system in a compact manner.

Means for Solving the Problems

[0010] The concentration measurement device according to an embodiment of the present invention is a concentration measurement device configured to measure the concentration of a gas flowing through a confluence block to which a plurality of gas supply lines are connected, and includes a light source that emits light to be incident on a flow path formed in the confluence block, a photodetector that receives the light emitted from the flow path, and an arithmetic control circuit that obtains the concentration of the gas flowing through the flow path based on the output of the photodetector. At least one of a translucent incident window for making the light from the light source incident on the flow path and a translucent emission window for emitting the light that has passed through the flow path is sealed and fixed to the confluence block.

[0011] In one embodiment, the confluence block has a plurality of sub-flow paths to which the plurality of gas supply lines are respectively connected, and a main flow path to which the plurality of sub-flow paths are connected, and the incident window and the emission window are sealed and fixed to both ends of the main flow path.

[0012] In one embodiment, the incident window is sealed and fixed to the confluence block by a first sealing member having a collimator, the light source and the first sealing member are connected by an optical transmission path member, the emission window is sealed and fixed to the confluence block by a second sealing member, and the photodetector and the second sealing member are connected by an optical transmission path member.

[0013] In one embodiment, the incident window is sealed and fixed to the confluence block by a first sealing member having the light source and a collimator, and the emission window is sealed and fixed to the confluence block by a second sealing member having the photodetector.

[0014] In one embodiment, the confluence block has a plurality of sub-flow paths to which the plurality of gas supply lines are respectively connected, and a main flow path to which the plurality of sub-flow paths are connected, the incident window is a common window member that also serves as the emission window, the common window member is sealed and fixed to one end of the main flow path, and a reflecting member that reflects the light incident on the flow path is fixed to the main flow path.

[0015] In one embodiment, an optical transmission path member for connecting the common window member and the light source, and an optical transmission path member for connecting the common window member and the photodetector are provided separately.

[0016] In one embodiment, the confluence block has a plurality of sub-channels to which the plurality of gas supply lines are respectively connected, and a main channel to which the plurality of sub-channels are connected. The incident window is a common window member that also serves as the exit window. The common window member is fixed so as to seal the measurement hole portion, and a reflecting member that reflects light incident on the measurement hole portion is arranged so as to face the common window member.

[0017] In one embodiment, it has a support member that is connected to a sealing member for sealing and fixing the common window member and extends along the measurement hole portion, and the reflecting member is supported by the support member.

[0018] In one embodiment, the main channel is formed by a through hole extending along the longitudinal direction of the confluence block, and each of the plurality of sub-channels extends in a direction intersecting the main channel and is formed by a hole provided so as to reach the main channel from the surface of the confluence block.

[0019] In one embodiment, the confluence block is a flow path block fixed on the base plate on the outlet side of an integrated unit formed on the base plate, where the plurality of gas supply lines are located.

Advantages of the Invention

[0020] According to the embodiment of the present invention, a concentration measurement device incorporated into a gas supply system in a compact manner is provided.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

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Figure 4

Figure 5

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Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. Also, in the actual use of the device, the direction of arrangement can be appropriately set, such as reversing the up and down or changing the up and down direction to the horizontal direction.

[0023] FIG. 1 shows a gas supply system 1 incorporating a concentration measuring device according to an embodiment of the present invention. The gas supply system 1 is configured to supply gas from a gas supply source 3 to a process chamber 7 of a semiconductor manufacturing apparatus via an integrated unit 10 provided with a plurality of gas supply lines 5. A vacuum pump 9 is connected to the process chamber 7, and gas can be supplied while the process chamber 7 and the flow path are evacuated.

[0024] The integrated unit 10 has a configuration in which a plurality of supply lines 5 are formed on a base plate. Each supply line 5 is formed in an arbitrary manner by fixing a flow path block (joint block), an on-off valve, a filter, a flow rate control device, etc. on the base plate with screws or the like and interconnecting them via, for example, a metal gasket. The integrated unit 10 can individually control the gas flow rate using the flow rate control devices 12 provided in each supply line 5. Note that in FIG. 1, for simplicity, only the flow rate control device 12, the on-off valves before and after it, and the outlet on-off valve after confluence are shown, but it goes without saying that various other elements such as bypass flow paths may be provided as necessary.

[0025] In the gas supply system 1, each supply line 5 provided in the integrated unit 10 is connected to a confluence block 14 disposed on the outlet side of the integrated unit 10. The confluence block 14 is a manifold block having a plurality of sub-flow paths to which each supply line 5 is connected and one main flow path to which the plurality of sub-flow paths are commonly connected, and is a flow path block fixed on the base plate on the outlet side of the integrated unit 10. The outlet of the confluence block 14 is connected to the process chamber 7, and any gas can be supplied from each supply line via the confluence block 14. Note that a plurality of confluence blocks 14 may be provided in the integrated unit 10, and in this case, a part of the supply line is connected to each confluence block.

[0026] The concentration measurement device 20 according to an embodiment of the present invention is composed of a gas unit 22 formed using the above-described confluence block 14 and an electrical unit 24 optically or electrically connected to the gas unit 22, and is configured to measure the concentration of the gas flowing through the confluence block 14.

[0027] Since the gas unit 22 constituting the concentration measurement device 20 may become high temperature depending on the temperature of the gas (for example, 100°C to 150°C), it is preferably formed using an optical system having high temperature resistance. On the other hand, the electrical unit 24 is typically provided in a room temperature environment separated from the gas unit 22 and is less affected by temperature. Hereinafter, the concentration measurement devices according to Embodiments 1 to 5 will be specifically described.

[0028] (Embodiment 1) FIG. 2 is a perspective view showing the confluence block 14 in which the gas unit 22 constituting the concentration measurement device 20 of Embodiment 1 is formed, and FIGS. 3(a) and (b) are longitudinal sectional views and side views showing the gas unit 22 provided in the confluence block 14.

[0029] As shown in FIG. 2, the confluence block 14 used in the present embodiment is fixed on a base plate 16 provided with an integrated unit, and has a main flow path L1 formed by an elongated through hole extending along the longitudinal direction D1 of the confluence block 14. A plurality of sub-flow paths L2 are connected to the main flow path L1. Each of the sub-flow paths L2 is formed by a hole provided so as to reach the main flow path from the upper surface of the confluence block 14, and extends in a direction (here, a perpendicular direction) intersecting the main flow path L1.

[0030] The through holes and holes forming the main flow path L1 and the sub-flow paths L2 can be easily formed in the confluence block 14 by drilling. The confluence block 14 may be made of, for example, stainless steel (particularly SUS316L), like other flow path blocks constituting the integrated unit.

[0031] At the opening on the inlet side of the sub-channel L2 formed on the upper surface of the confluence block 14, each supply line provided in the integrated unit (more specifically, the outlet of the on-off valve provided at the final stage of each line) is connected. In this configuration, the gases GasA, GasB, and GasC flowing through an arbitrary supply line of the integrated unit can be flowed into the main channel L1 via the sub-channel L2 of the confluence block 14. In the embodiments shown in FIGS. 2 and 3, as the confluence block 14, a triple block to which three supply lines are connected is used, but it is not limited thereto, and a block to which an arbitrary number of gas supply lines are connected can be used.

[0032] Further, an outlet block 14A in which an L-shaped outflow channel L3 communicating with the main channel L1 is formed is fixed to the confluence block 14. Further, a channel for connecting the outflow channel L3 of the outlet block 14A and the main channel L1 is formed in the confluence block 14. The outlet block 14A is firmly fixed to the confluence block 14 by screwing via a gasket, and gas can flow out from the main channel L1 through the outflow channel L3.

[0033] The opening of the outflow channel L3 formed on the upper surface of the outlet block 14A is connected to an on-off valve (shut-off valve) (not shown). By using the shut-off valve, the stop of the gas flow from the integrated unit can be performed more reliably. Further, the outflow channel of the shut-off valve is connected to a channel block provided with a tubular joint serving as a gas outlet, and when the shut-off valve is open, gas is supplied to the downstream channel and the process chamber via the tubular joint.

[0034] Note that, as long as the confluence block 14 has a plurality of sub-channels L2 and a main channel L1 and is fixed to the base plate 16, various types other than the mode shown in FIG. 2 can be used. FIGS. 4(a) and (b) show confluence blocks 14 of other modes. The confluence block 14 shown in FIGS. 4(a) and (b) is configured by using an outlet block 14B having a joint portion 14b on the side surface and an L-shaped outflow channel L3 that communicates the joint portion 14b with the upper surface opening. Different from the outflow channel L3 of the outlet block 14A shown in FIG. 2, the outflow channel L3 of the outlet block 14B does not directly communicate with the main channel L1.

[0035] In the confluence block 14 shown in FIGS. 4(a) and (b), the upper surface opening of the outlet sub-channel L2’ (one of the sub-channels) and the upper surface opening of the outlet block 14B are connected to a shut-off valve 18 arranged so as to straddle both of them. In this configuration, the outlet sub-channel L2’ that communicates with the main channel L1 is used to flow the gas from the main channel L1 through the shut-off valve 18 into the outflow channel L3 of the outlet block 14B. Then, gas can be supplied from the side surface joint portion 14b of the outlet block 14B to the process chamber through a channel.

[0036] As described above, various types of confluence blocks 14 can be used. Hereinafter, an example of forming the gas unit 22 using the confluence block 14 shown in FIG. 2 will be described. However, it goes without saying that in the confluence block 14 of other modes, the gas unit 22 can be formed in the same manner as the embodiment described below.

[0037] FIGS. 3(a) and (b) show the configuration of the gas unit 22 of the concentration measuring device 20 of the present embodiment. As shown in FIG. 3(a), the gas unit 22 has a light-transmissive incident window 26 and a light-transmissive exit window 28 arranged at the end of the main channel L1 of the confluence block 14. The incident window 26 and the exit window 28 are sealed and fixed to both ends of the confluence block 14 using sealing members 27 and 29.

[0038] In this embodiment, the main flow path L1 is formed by sealing both ends of a through hole formed to extend along the longitudinal direction of the confluence block 14 with sealing members 27 and 29 (here, blind joints), respectively. And by using this sealing member, the optical system of the gas unit 22 that constitutes the concentration measuring device 20 is arranged.

[0039] The sealing member 27 (hereinafter sometimes referred to as the first sealing member) for fixing the incident window 26 is provided with a collimator. Also, the sealing member 29 (hereinafter sometimes referred to as the second sealing member) for fixing the exit window 28 is provided with a condenser lens. The incident window 26 and the exit window 28 are arranged to face each other with the main flow path L1 interposed therebetween, and the light incident from the incident window 26 and traveling straight through the main flow path L1 can be made to exit from the exit window 28. The main flow path L1 of the confluence block 14 is used as the optical path of the measurement light.

[0040] The first sealing member 27 for fixing the incident window 26 is provided with an optical transmission path member connected to the collimator, specifically, an optical fiber 30. The optical fiber 30 is used to transmit measurement light (here, ultraviolet light) from the electric unit 24 to the gas unit 22. The transmitted light is converted into parallel light by the collimator and then incident on the main flow path L1 through the incident window 26.

[0041] Also, the second sealing member 29 for fixing the exit window 28 is provided with an optical fiber 31 for receiving the light condensed by the condenser lens. The optical fiber 31 is used to transmit the light that has passed through the main flow path L1 of the gas unit 22 to the electric unit 24.

[0042] Note that in this specification, light includes not only visible light rays but also at least infrared rays and ultraviolet rays, and can include electromagnetic waves of any wavelength. Also, the light transmissivity means that the internal transmittance with respect to the light incident on the main flow path L1 is sufficiently high to enable concentration measurement.

[0043] The incident window 26 and the exit window 28 are formed, for example, of circular sapphire plates with a thickness of 0.5 mm to 2 mm and a diameter of 5 mm to 30 mm. As the incident window 26 and the exit window 28, sapphire having resistance and high transmittance to the detection light used for concentration measurement of ultraviolet light or the like and being mechanically and chemically stable is preferably used, but other stable materials such as quartz glass can also be used.

[0044] In order to more reliably seal and fix the incident window 26 and the exit window 28 to the main flow path L1, a metal gasket (for example, made of SUS316L) may be disposed between the incident window 26 and the exit window 28 and the first and second sealing members 27, 29. The metal gasket may be provided with an annular convex portion that is crushed to improve the sealing performance. The sealing performance can be ensured by replacing the metal gasket with a new one when replacing the incident window 26 and the exit window 28.

[0045] As shown in Fig. 3(a), a diameter-expanded portion may be formed at the end of the main flow path L1 at the attachment portions of the incident window 26 and the exit window 28 in the confluence block 14. By supporting the peripheral portions of the incident window 26 and the exit window 28 on the bottom surface (support surface) of this diameter-expanded portion, the incident window 26 and the exit window 28 can be sealed and fixed stably with high sealing performance. A fitting recess having a shape adapted to the incident window 26 and the exit window 28 may be formed on the support surface of the diameter-expanded portion. Also, the above-described metal gasket with an annular convex portion may be disposed between the support surface of the diameter-expanded portion and the incident window 26 and the exit window 28 to improve the sealing performance and maintainability.

[0046] Examples of the blind joints used as the first and second sealing members 27 and 29 may be metal plugs having male threads coated with a sealing material on their circumferential surfaces. By screwing these plugs into the female threads formed at both ends of the confluence block 14, the incident window 26 and the exit window 28 can be sealed and fixed while being pressed against the support surface. However, the first and second sealing members 27 and 29 may be of any form as long as they can fix the incident window 26 and the exit window 28 while properly sealing the main flow path L1. For example, they may be caulked and fixed.

[0047] The gas unit 22 configured as described above can receive incident light from the electrically separated unit 24 and send the light after passing through the main flow path L1 to the electrical unit 24. Since the gas unit 22 is formed using the confluence block 14 of the integrated unit, it can be compactly incorporated into the gas supply system with a relatively simple configuration, reducing the installation space for the gas unit that was required conventionally. Also, as the electrical unit 24, it is possible to use the units that have been conventionally used, enabling cost reduction.

[0048] FIG. 5 shows the configuration of the electrical unit 24 used in this embodiment. As shown in FIG. 5, the electrical unit 24 includes a light source 40 that emits light for entering the confluence block 14 (see FIG. 3), a photodetector 44 that receives the light emitted from the confluence block 14, and an arithmetic control circuit 46 that obtains the concentration of the gas by calculation based on the detection signal output by the photodetector 44 (a detection signal corresponding to the intensity of the received light). The electrical unit 24 is also provided with a reference photodetector 48 that receives the reference light from the light source 40. In this embodiment, the electrical unit 24 is optically connected to the gas unit 22 by optical fibers 30 and 31.

[0049] The light source 40 includes two light-emitting elements (here, LEDs) 41 and 42 that emit ultraviolet light with different wavelengths. Different-frequency drive currents are passed through the light-emitting elements 41 and 42 using an oscillation circuit, and by performing frequency analysis (for example, fast Fourier transform or wavelet transform), the intensity of light corresponding to each wavelength component can be measured from the detection signal detected by the photodetector 44.

[0050] As the light-emitting elements 41 and 42, light-emitting elements other than LEDs, for example, LDs (laser diodes), can also be used. Further, instead of using a combined light of multiple different wavelengths as the light source, a single-wavelength light source can be utilized. In this case, the optical combiner and the frequency analysis circuit can be omitted. Three or more light-emitting elements may be provided, or it may be configured to generate incident light using only an arbitrarily selected light-emitting element among those provided. A temperature-measuring resistor may be attached to the light source 40. Furthermore, the light emitted by the light-emitting element is not limited to ultraviolet light and may be visible light or infrared light. The wavelength of the light may be appropriately selected based on the light absorption characteristics of the gas to be measured. In this embodiment, ultraviolet light is used to measure the concentration of an organometallic gas (for example, trimethylgallium (TMGa) or trimethylaluminum (TMAl)) that absorbs ultraviolet light.

[0051] The light source 40 and the reference photodetector 48 are attached to the beam splitter 49. The beam splitter 49 functions to make a part of the light from the light source 40 incident on the reference photodetector 48 and guide the remaining light to the gas unit 22 through the optical fiber 30. As the light-receiving elements constituting the photodetector 44 and the reference photodetector 48, photodiodes or phototransistors are preferably used.

[0052] The arithmetic control circuit 46 is composed of, for example, a processor, a memory, etc. provided on a circuit board, includes a computer program that executes a predetermined arithmetic operation based on an input signal, and can be realized by a combination of hardware and software. In the illustrated embodiment, the arithmetic control circuit 46 is built in the electric unit 24, but a part (such as a CPU) or all of its components may be provided outside the electric unit 24.

[0053] In the concentration measuring device 20 described above, the light with wavelength λ that has passed through the main flow path L1 of the confluence block 14 is absorbed by the gas present in the main flow path L1 according to the concentration of the gas. Then, the arithmetic control circuit 46 can measure the absorbance Aλ at the wavelength λ by performing frequency analysis on the detection signal from the photodetector 44. Further, based on the Lambert-Beer's law shown in the following formula (1), the molar concentration C M can be calculated from the absorbance Aλ. Aλ = -log 10 (I / I0) = α’LC M ···(1)

[0054] In the above formula (1), I0 is the intensity of the incident light incident on the main flow path L1, I is the intensity of the light that has passed through the gas in the main flow path L1, α’ is the molar absorption coefficient (m 2 / mol), L is the optical path length (m) of the main flow path L1, and C M is the molar concentration (mol / m 3 ). The molar absorption coefficient α’ is a coefficient determined by the substance. I / I0 is generally called the transmittance. When the transmittance I / I0 is 100%, the absorbance Aλ becomes 0, and when the transmittance I / I0 is 0%, the absorbance Aλ becomes infinite.

[0055] Regarding the incident light intensity I0 in the above formula, when there is no light-absorbing gas in the main flow path L1 (for example, when the gas that does not absorb ultraviolet light is filled or when it is evacuated), the intensity of the light detected by the photodetector 44 may be regarded as the incident light intensity I0. Further, as shown in FIG. 3, the optical path length L of the main flow path L1 is the distance from the surface on the gas side of the incident window 26 to the surface on the gas side of the emission window 28, and this distance is known in advance.

[0056] As described above, the concentration measuring device 20 of the present embodiment can obtain the concentration of the gas based on the absorbance of the light that has passed through the main flow path L1. However, the concentration measuring device 20 may be configured to obtain the concentration of the gas in consideration of the pressure and temperature of the gas flowing through the main flow path L1 of the confluence block 14. Hereinafter, a mode of obtaining the concentration of the measurement gas (that is, the gas to be measured) contained in the mixed gas in consideration of the pressure and temperature will be described.

[0057] As described above, the Lambert-Beer's formula (1) holds, but the molar concentration C M refers to the amount of substance of the gas per unit volume, so C M can be expressed as C = n / V. Here, n is the amount of substance (mol) of the gas, that is, the number of moles, and V is the volume (m 3 ).

[0058] Since the measurement target is a gas, from the ideal gas law PV = nRT, the molar concentration C M = n / V = P / RT is derived. Substituting this into the Lambert-Beer's formula and applying -ln(I / I0) = ln(I0 / I), the following formula (2) is obtained. ln(I0 / I) = αL(P / RT) ···(2)

[0059] In formula (2), R is the gas constant = 0.0623 (Torr·m 3is in units of / K / mol, P is pressure (Torr), and T is temperature (K). Further, the molar extinction coefficient α in Equation (2) is the molar extinction coefficient with respect to the natural logarithm of the transmittance, and satisfies the relationship α’ = 0.434α with respect to α’ in Equation (1).

[0060] Here, the pressure that the pressure sensor can detect is the total pressure Pt (Torr) of the mixed gas including the measurement gas and the carrier gas. On the other hand, the gas related to absorption is only the measurement gas, and the pressure P in the above Equation (2) corresponds to the partial pressure Pa of the measurement gas. Therefore, when expressing Equation (2) using the equation Pa = Pt·Cv, which represents the partial pressure Pa of the measurement gas in terms of the measurement gas concentration Cv (volume %) in the whole gas and the total pressure Pt, the relationship between the concentration (volume %) of acetone and the absorbance considering pressure and temperature is the absorbance coefficient α a of the measurement gas, and can be expressed by the following Equation (3). ln(I0 / I) = α a L(Pt·Cv / RT) ···(3)

[0061] Further, when Equation (3) is transformed, the following Equation (4) is obtained. Cv = (RT / α a LPt)·ln(I0 / I) ···(4)

[0062] Therefore, according to Equation (4), based on each measured value (gas temperature T, total pressure Pt, and transmitted light intensity I), it is possible to obtain the measurement gas concentration (volume %) at the measurement light wavelength by calculation. In this way, the concentration of the absorbing gas in the mixed gas can be obtained considering the gas temperature and gas pressure. Note that the absorbance coefficient α a can be obtained in advance from the measured values (T, Pt, I) when a measurement gas with a known concentration (for example, 100% concentration) is passed, according to Equation (3) or (4). The absorbance coefficient α a thus obtained is stored in the memory, and when performing the concentration calculation of the measurement gas with an unknown concentration based on Equation (4), the absorbance coefficient α a can be read from the memory and used.

[0063] A temperature sensor for measuring the gas temperature T flowing through the main flow path L1 may be separately attached to the confluence block 14, or, when the flow rate control device 12 provided in the integrated unit has a temperature sensor, the output of this temperature sensor may be used as the gas temperature T. Also, a pressure sensor for measuring the total pressure Pt may be separately attached to the confluence block 14, or, when the flow rate control device 12 has a pressure sensor on the downstream side, it is also possible to measure the total pressure Pt using this pressure sensor.

[0064] (Embodiment 2) FIGS. 6(a) and (b) are a longitudinal sectional view and a side view showing the gas unit 22a included in the concentration measuring device of Embodiment 2. Also in this embodiment, the gas unit 22a is configured using a confluence block 14 (see FIGS. 2 and 4) fixed to the integrated unit. Hereinafter, for components similar to those in Embodiment 1, the same reference numerals may be given and detailed description may be omitted.

[0065] In the gas unit 22a of this embodiment, a sealing member 27a incorporating an LED that is also used as a light source and a sealing member 29a incorporating a photodiode that is also used as a photodetector are provided at both ends of the confluence block 14. The sealing member 27a is used to seal and fix the incident window 26, and the sealing member 29a is used to seal and fix the exit window 28.

[0066] Thus, since the gas unit 22a of this embodiment is configured to include a light source and a photodetector, it is not necessary to provide a light source and a photodetector in the electrical unit connected to the gas unit 22a. In this embodiment, the electrical unit may be provided with an arithmetic control circuit 46 similar to that in Embodiment 1.

[0067] In the concentration measuring device of the present embodiment, the gas unit 22a receives, from the arithmetic control circuit provided in the electric unit, a signal for controlling the light emission of the LED built in the sealing member 27a via the wiring cable 32, and makes the measurement light enter the main flow path L1 through the incident window 26. Further, the light that has passed through the main flow path L1 is received by the photodiode of the sealing member 29a through the exit window 28. Then, it is converted into an electric signal by the photodiode and sent to the arithmetic control circuit of the electric unit via the wiring cable 33. The arithmetic control circuit can obtain, by arithmetic operation, the concentration of the gas flowing through the main flow path L1 based on the received electric signal, in the same manner as in the first embodiment.

[0068] The concentration measuring device of the second embodiment configured as described above can also be compactly incorporated into the gas supply system with a relatively simple configuration, and can reduce the installation space of the gas unit that was necessary in the past.

[0069] (Embodiment 3) FIGS. 7(a) and (b) are a longitudinal sectional view and a side view showing the gas unit 22b included in the concentration measuring device of the third embodiment. Also in this embodiment, the gas unit 22b is configured using the confluence block 14 (see FIGS. 2 and 4) fixed to the integrated unit. Hereinafter, for the components similar to those in the first embodiment, the same reference numerals may be given and detailed description may be omitted.

[0070] In the gas unit 22b of the present embodiment, a common window member 23 that also serves as an incident window and an exit window is sealed and fixed by a sealing member 27b at one end of the confluence block 14. Further, a reflection member 25 is sealed and fixed by a sealing member 29b at the other end of the confluence block 14. The reflection surface of the reflection member 25 is provided perpendicular to the traveling direction of the incident light or the central axis of the flow path, and can reflect the light that has traveled straight through the main flow path L1 in the same direction.

[0071] The reflecting member 25 may be, for example, a sapphire plate (the emission window 28 in Embodiments 1 and 2) with an aluminum layer formed as a reflection layer on the back surface by sputtering. Further, the reflecting member 25 may include a dielectric multilayer film as the reflection layer. By using the dielectric multilayer film, light in a specific wavelength range (for example, near ultraviolet light) can be selectively reflected. The dielectric multilayer film is composed of a laminate of a plurality of optical films with different refractive indices (a laminate of a high refractive index thin film and a low refractive index thin film). By appropriately selecting the thickness and refractive index of each layer, light of a specific wavelength can be reflected or transmitted.

[0072] In addition, since the dielectric multilayer film can reflect light at an arbitrary ratio, for example, when the incident light is reflected by the reflecting member 25, not all of the incident light is reflected 100%, but a part (for example, 10%) is transmitted. Thus, the transmitted light can be received by a photodetector or the like installed outside the reflecting member 25, and the transmitted light can also be used as reference light.

[0073] The gas unit 22b of the present embodiment is optically connected to the same electric unit 24 as in Embodiment 1. However, since the incident and emission of light are performed at one end of the confluence block 14, both the incident optical fiber 30 and the emission optical fiber 31 are connected to the sealing member 27b.

[0074] In the concentration measuring device of the present embodiment, the light from the light source 40 provided in the electric unit 24 is guided by the optical fiber 30 to the common window member 23 of the main flow path L1 and is incident on the main flow path L1 from the common window member 23. Further, the light that has passed through the main flow path L1 and is reflected by the reflecting member 25 is emitted from the common window member 23 and is guided by the optical fiber 31 to the photodetector 44 of the electric unit.

[0075] Thus, by separately providing the optical fiber 30 for guiding light to the main flow path L1 and the optical fiber 31 for guiding the light emitted from the main flow path L1, the influence of stray light can be reduced. However, in another aspect, a single optical transmission path member that serves both for incident light and emitted light, such as an optical fiber bundle, may be used to connect the light source and the measurement light detector to the measurement cell.

[0076] The configuration of the reflection type concentration measuring device is described, for example, in Patent Document 2. In the present embodiment, various aspects described in Patent Document 2 can be applied to the design of the optical system.

[0077] The concentration measuring device of Embodiment 3 configured as described above can also be compactly incorporated into the gas supply system with a relatively simple configuration, reducing the installation space for the gas unit that was conventionally required.

[0078] Also, in the present embodiment, the optical path length L of the main flow path L1 is defined as twice the distance from the surface on the gas contact side of the incident window 26 to the surface on the gas contact side of the reflecting member 25. Therefore, although having the same dimensions, an optical path length twice as long can be obtained. As a result, the measurement accuracy can be improved despite the miniaturization. Further, in the concentration measuring device of Embodiment 3, since light is incident and emitted only on one side of the confluence block 14, the number of components can be reduced.

[0079] (Embodiment 4) FIGS. 8(a) and (b) are a top view and a cross-sectional view from the side showing the gas unit 22c included in the concentration measuring device of Embodiment 4. The gas unit 22c of the present embodiment is also configured using the confluence block 14 fixed to the integrated unit. Hereinafter, the same reference numerals may be given to the same components as those in Embodiment 3, and detailed description thereof may be omitted.

[0080] Unlike those in the first to third embodiments, the gas unit 22c in this embodiment is configured to cause light to enter in the same direction as the sub-channel L2 instead of the main channel L1 and measure the intensity of the transmitted light. The gas unit 22c utilizes one of the sub-channels L2 for the arrangement of the optical system, and arranges the optical system for concentration measurement on the upper surface of the confluence block 14. Also, similar to the third embodiment, the gas unit 22c constitutes a reflection-type concentration measurement device. Hereinafter, in order to distinguish the sub-channel L2 where the optical system is arranged from the sub-channel L2 connected to the gas supply line, it may be referred to as a measurement hole portion. The measurement hole portion is typically a hole extending in a direction parallel to the sub-channel L2.

[0081] The gas unit 22c has a collimator 50 provided on the upper surface of the confluence block 14 and a window pressing member 52 for sealing and fixing the common window member 23, and the collimator 50 and the window pressing member 52 function as a sealing member 27b. The collimator 50 is provided with a collimator lens 50a, and can make the light from the optical fiber 30 into parallel light and then enter the measurement hole portion along the direction of the sub-channel L2 through the common window member 23. The collimator 50 and the window pressing member 52 can be fixed to the confluence block 14 by inserting bolts into bolt holes 55.

[0082] Also, on the lower surface side of the confluence block, a reflecting member 25 is provided so as to face the common window member 23. The reflecting member 25 is sealed and fixed by a sealing member 29b. The light reflected by the reflecting member 25 returns to the measurement hole portion, enters the collimator 50 through the common window member 23, and then is transmitted to the photodetector of the electric unit via the optical fiber 31. Also in this embodiment, the gas concentration can be obtained by calculation based on the output of the photodetector. Note that the optical path length L in this embodiment is obtained as twice the distance between the common window member 23 and the reflecting member 25 in the vertical direction.

[0083] In this embodiment, since the main flow path L1 is not used as an optical path, it is not necessary to arrange optical systems at both ends of the main flow path L1. Therefore, as shown in FIGS. 8(a) and (b), the main flow path L1 is formed by sealing, with a sealing member 54, a long hole that extends to the innermost sub-flow path L2 instead of a through hole. Further, in another aspect, a joint member may be provided instead of the sealing member 54, and this may be used as a gas outlet, and a configuration may be adopted in which gas is flowed downstream.

[0084] (Embodiment 5) FIGS. 9(a) and (b) are cross-sectional views from the side and cross-sectional views from the end face showing the gas unit 22d included in the concentration measuring device of Embodiment 5. The gas unit 22d of this embodiment is also configured using a confluence block 14 fixed to an integrated unit. Hereinafter, for the same components as in Embodiments 3 and 4, the same reference numerals may be given and detailed descriptions may be omitted.

[0085] As shown in FIGS. 9(a) and (b), the gas unit 22d constitutes a reflection-type concentration measuring device that reciprocates light along the direction of the sub-flow path L2, similar to Embodiment 4. However, instead of sealing and fixing a reflecting member to the lower surface side of the confluence block 14 as in Embodiment 4, a support member 58 connected to the sealing member 27b of the common window member 23 provided on the upper surface of the confluence block 14 is used to support the reflecting member 25.

[0086] In the gas unit 22d, the sealing member 27b is composed of a collimator 50 and a window receiving member 56. The support member 58 extends from the window receiving member 56 and can be inserted from above along the measurement hole portion with the reflecting member 25 attached.

[0087] According to the above configuration, without particularly processing the confluence block 14, one of the sub-flow paths L2 can be used to dispose the reflecting member 25 below the flow path from above the confluence block 14. In this embodiment, in addition to the collimator 50 and the common window member 23, even the reflecting member 25 can be integrated, which is highly convenient.

[0088] The support member 58 preferably has a length reaching the main flow path L1 in order to perform good gas concentration measurement. The support member 58 is not limited to the plate-like shape shown in the figure, and may be a cylindrical shape with one side cut, or may be composed of two bars. The support member 58 can have any form as long as it does not cross the optical path of the measurement light and does not inhibit the gas from reaching the optical path.

[0089] As described above, the concentration measurement devices according to Embodiments 1 to 5 have been described. However, any of the concentration measurement devices can be compactly incorporated into the gas supply system by using the confluence block, and the concentrations of various gases flowing through the confluence block can be appropriately measured. Note that the present invention is not construed as being limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention.

Industrial Applicability

[0090] The concentration measurement device according to the embodiment of the present invention is preferably used to measure the concentration of a gas incorporated into a gas supply system.

Explanation of Signs

[0091] 1 Gas supply system 3 Gas supply source 5 Supply line 7 Process chamber 9 Vacuum pump 10 Integrated unit 12 Flow rate control device 14 Confluence block 16 Base plate 20 Concentration measurement device 22 Gas unit 23 Common window member 24 Electric unit 25 Reflective member 26 Incident window 27 Sealing member 28 Exit window 29 Sealing member 30, 31 Optical fiber 32 and 33 wiring cables 40 light source 44 photodetector 46 arithmetic control circuit 48 reference photodetector

Claims

Claim 1: A concentration measuring device configured to measure the concentration of a gas flowing through a confluence block to which a plurality of gas supply lines are connected, a light source that emits light to be incident on a flow path formed in the confluence block, a photodetector that receives the light emitted from the flow path, and an arithmetic control circuit that obtains the concentration of the gas flowing through the flow path based on the output of the photodetector and comprising, with respect to the confluence block, at least one of a translucent incident window for causing the light from the light source to be incident on the flow path and a translucent emission window for emitting the light that has passed through the flow path is sealed and fixed, the confluence block is a flow path block fixed on a base plate on the outlet side of an integrated unit in which the plurality of gas supply lines are formed on the base plate, and is also a manifold block having a plurality of sub-flow paths to which the plurality of gas supply lines are respectively connected and a main flow path to which the plurality of sub-flow paths are commonly connected, the main flow path is formed using a through hole extending along the longitudinal direction of the confluence block, and each of the plurality of sub-flow paths is provided so as to extend from the surface of the confluence block to the main flow path in a direction intersecting the main flow path, each of the inlet-side openings of the plurality of sub-flow paths formed on the upper surface of the confluence block is connected to each of the plurality of gas supply lines provided in the integrated unit, a concentration measuring device in which the incident window and the emission window are sealed and fixed to both ends of the main flow path.

2. The incident window is sealed and fixed to the confluence block by a first sealing member having a collimator, and the light source and the first sealing member are connected by an optical transmission path member, The emission window is sealed and fixed to the confluence block by a second sealing member, and the photodetector and the second sealing member are connected by an optical transmission path member. The concentration measuring device according to claim 1.

3. The incident window is sealed and fixed to the confluence block by a first sealing member having the light source and a collimator, The emission window is sealed and fixed to the confluence block by a second sealing member having the photodetector. The concentration measuring device according to claim 1.

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