Concentration measurement device, concentration measurement method, starting material vaporization system, and concentration measurement method for starting material vaporization system

Abstract

A concentration measurement device (5) for measuring the concentration of a starting material gas that is included in a mixed gas (MG), the concentration measurement device (5) comprising: a partial pressure sensor (51) that detects the partial pressure of the starting material gas included in the mixed gas (MG), and outputs a partial pressure signal (Pv) indicating said partial pressure; a total pressure sensor (52) that detects the total pressure, which is the pressure of the mixed gas (MG), and outputs a total pressure signal (Pt) indicating said total pressure; a delay filter (53) that performs processing to delay the response speed of the total pressure signal (Pt), and outputs a delayed total pressure signal (Pt'), which is the total pressure signal after said processing; and a calculation unit (54) that calculates the concentration of the starting material gas included in the mixed gas (MG) on the basis of the partial pressure signal (Pv) and the delayed total pressure signal (Pt').

Description

Concentration measuring device, concentration measuring method, raw material vaporization system, and concentration measuring method in raw material vaporization system

[0001] The present invention relates to a concentration measuring device, a concentration measuring method, a raw material vaporization system, and a concentration measuring method in a raw material vaporization system.

[0002] Conventionally, concentration measuring devices that measure the concentration of a component to be measured contained in a gas have been provided, and calculate the concentration based on the partial pressure of the component to be measured contained in the gas and the total pressure of the gas.

[0003] For example, Patent Document 1 discloses a concentration measuring device for a raw material vaporization system. Here, the raw material vaporization system refers to a system that introduces a carrier gas into a liquid or solid raw material contained in a tank, vaporizes the raw material, and supplies a mixed gas containing the resulting raw material gas and the carrier gas.

[0004] The concentration measuring device in this type of raw material vaporization system measures the concentration of the raw material gas by calculating the ratio of the partial pressure, which is the pressure of the raw material gas, to the total pressure, which is the pressure inside the tank. Conventionally, this concentration measuring device has used, for example, a non-dispersive infrared absorption sensor (hereinafter referred to as an "NDIR sensor") as the partial pressure sensor that measures the partial pressure, and a capacitance diaphragm vacuum gauge (hereinafter referred to as a "CDG") as the total pressure sensor that measures the total pressure.

[0005] In general, in order to obtain a sufficient signal-to-noise ratio, partial pressure sensors often perform processing such as moving averaging on the detected partial pressure and output a partial pressure signal indicating the partial pressure. Furthermore, NDIR sensors, which are often used as partial pressure sensors, undergo processing such as chopping, so the response speed of the partial pressure signal output by the NDIR is limited by the chopping frequency. As a result, the partial pressure signal output by the partial pressure sensor changes with a delay relative to pressure changes in the concentration measuring device.

[0006] On the other hand, total pressure sensors generally have a much better S / N ratio than partial pressure sensors, so they do not typically perform processing to obtain a sufficient S / N ratio, such as moving averaging, and even if they do, they generally only perform processing that provides a response that is much faster than that of partial pressure sensors. Therefore, since total pressure sensors do not perform processing such as moving averaging, the total pressure signal output by a total pressure sensor changes more quickly with pressure changes in the concentration measuring device than the partial pressure signal output by a partial pressure sensor. As a result, a difference in response speed occurs between the partial pressure signal output by a partial pressure sensor and the total pressure signal output by a total pressure sensor.

[0007] Examples of pressure changes in this concentration measuring device include pressure rises and falls. Specifically, a pressure rise occurs in the concentration measuring device when, for example, the supply of carrier gas is started upstream of the concentration measuring device, and a pressure fall occurs in the concentration measuring device when, for example, the supply of carrier gas is stopped. Furthermore, a pressure rise occurs in the concentration measuring device when, for example, a chamber provided downstream of the concentration measuring device is opened to the atmosphere, and a pressure fall occurs in the concentration measuring device when, for example, the chamber is evacuated. When a pressure change such as a pressure rise or fall occurs in the concentration measuring device, the partial pressure signal changes later than the pressure change compared to the total pressure signal. Therefore, a difference occurs between the response speed of the partial pressure signal and the response speed of the total pressure signal, making it impossible to accurately measure the concentration of the source gas during pressure changes such as a pressure rise or fall.

[0008] Japanese Patent Application Laid-Open No. 2022-38365

[0009] The present invention has been made to solve the above problems, and its main objective is to accurately measure the concentration of the component to be measured contained in the gas when the pressure of the concentration measuring device changes, such as when the pressure rises or falls.

[0010] That is, the concentration measuring device according to the present invention is a concentration measuring device for measuring the concentration of a target component contained in a gas, and is characterized by comprising: a partial pressure sensor that detects the partial pressure of the target component contained in the gas and outputs a partial pressure signal indicative of the partial pressure; a total pressure sensor that detects the total pressure, i.e., the pressure of the gas, and outputs a total pressure signal indicative of the total pressure; a lag filter that processes the total pressure signal to delay the response speed and outputs a delayed total pressure signal, which is the processed total pressure signal; and a calculation unit that calculates the concentration of the target component contained in the gas based on the partial pressure signal and the delayed total pressure signal. With this configuration, the lag filter processes the total pressure signal to delay the response speed and outputs a delayed total pressure signal, which is the processed total pressure signal, thereby reducing the difference in response speed between the partial pressure signal and the delayed total pressure signal. As a result, the concentration of the target component contained in the gas can be accurately measured when the pressure in the concentration measuring device changes, such as when the pressure rises or falls.

[0011] Here, it is desirable that the lag filter be one that performs a moving average of the total pressure signal, so that noise in the total pressure signal can be removed by performing a moving average of the total pressure signal.

[0012] Furthermore, the partial pressure signal is preferably output as a moving average of the detected partial pressure, and the lag filter is preferably set so that the moving average interval of the total pressure signal is within a range of -37.5% to 37.5% of the moving average interval of the detected partial pressure. In this case, both the delayed total pressure signal and the partial pressure signal are output as moving averages, and the moving average interval of the total pressure signal is set so that it is within a range of -37.5% to 37.5% of the moving average interval of the detected partial pressure. Therefore, the difference between the response speed of the partial pressure signal and the response speed of the delayed total pressure signal is further reduced, allowing for more accurate measurement of the concentration of the component to be measured.

[0013] Furthermore, the partial pressure sensor may be an NDIR sensor, which can measure substances that absorb infrared rays with high sensitivity and can measure partial pressure using a measuring device that is simple in structure and inexpensive.

[0014] Furthermore, the total pressure sensor may use a CDG. A total pressure sensor using a CDG can measure total pressure with high sensitivity even when the total pressure value is small. However, a CDG has a faster response speed than an NDIR sensor and requires almost no processing such as moving average to improve the S / N ratio, resulting in a difference in response speed between the total pressure signal and the partial pressure signal. As a countermeasure, a delay filter processes the total pressure signal output by the CDG to delay the response speed, thereby reducing the difference in response speed.

[0015] The concentration measuring device preferably further includes a display control unit that outputs the concentration calculated by the calculation unit, so that the calculated concentration is output by the display control unit, allowing the user to confirm whether the concentration measuring device is accurately measuring the concentration.

[0016] The raw material vaporization system may be a raw material vaporization system that introduces a carrier gas into a liquid or solid raw material contained in a tank to vaporize it, and supplies a mixed gas containing the resulting raw material gas and the carrier gas. The raw material vaporization system may include a concentration measuring device that includes a partial pressure sensor that detects the partial pressure of the raw material gas and outputs a partial pressure signal indicating the partial pressure; a total pressure sensor that detects the total pressure in the tank and outputs a total pressure signal indicating the total pressure; a delay filter that processes the response speed of the total pressure signal and outputs a delayed total pressure signal that is the processed total pressure signal; and a calculation unit that calculates the concentration of the raw material gas based on the partial pressure signal and the delayed total pressure signal. In this raw material vaporization system, the delay filter outputs a delayed total pressure signal, thereby reducing the difference between the response speed of the partial pressure signal and the response speed of the delayed total pressure signal. Therefore, the raw material gas concentration can be accurately measured during pressure changes, such as a rise or fall in the pressure of the concentration measuring device. As a result, feedback control based on the measured raw material gas concentration can be stably performed, thereby stably controlling the raw material gas concentration in the raw material vaporization system.

[0017] A concentration measurement method for measuring the concentration of a component contained in a gas includes detecting a partial pressure of the component contained in the gas and outputting the partial pressure as a partial pressure signal, detecting a total pressure, which is the pressure of the gas, and outputting the total pressure as a total pressure signal, processing the total pressure signal to delay the response speed, outputting a delayed total pressure signal, which is the total pressure signal after the processing, and calculating the concentration of the component contained in the gas based on the partial pressure signal and the delayed total pressure signal. This concentration measurement method reduces the difference between the response speed of the partial pressure signal and the response speed of the delayed total pressure signal, thereby enabling more accurate measurement of the concentration of a component contained in the gas when the pressure changes.

[0018] Furthermore, it is desirable that the concentration measurement method be used in a raw material vaporization system that introduces a carrier gas into a liquid or solid raw material contained in a tank to vaporize it, and supplies a mixed gas containing the resulting raw material gas and the carrier gas, and that the concentration of the raw material gas be measured. This concentration measurement method performs processing to delay the response speed of the total pressure signal and outputs a delayed total pressure signal, which is the total pressure signal after the processing, thereby reducing the difference in response speed between the partial pressure signal and the delayed total pressure signal. As a result, in the raw material vaporization system, the concentration of the raw material gas can be measured more accurately when the concentration measuring device experiences pressure changes, such as a rise or fall in pressure.

[0019] According to the present invention as described above, the concentration of a measurement target component contained in a gas can be accurately measured when the pressure of the concentration measuring device changes, such as when the pressure rises or falls.

[0020] 1 is a schematic diagram of an entire raw material vaporization system according to one embodiment of the present invention; FIG. 2 is a schematic diagram of a concentration measurement device according to the same embodiment; FIG. 3 is a graph of (a) pressure indication value (b) concentration calculation value according to the same embodiment; and FIG. 4 is a graph of (a) pressure indication value (b) concentration calculation value according to a conventional example.

[0021] A raw material vaporization system according to one embodiment of the present invention will be described below with reference to the drawings. Note that, for ease of understanding, all of the drawings shown below are drawn in a schematic manner, with appropriate omissions or exaggerations. Identical components are designated by the same reference numerals, and their description will be omitted where appropriate.

[0022] 1. System Configuration The source material vaporization system 100 of this embodiment is used, for example, in a semiconductor manufacturing process, and supplies a source gas such as isopropyl alcohol (IPA) at a predetermined concentration to a drying processing chamber of a wafer cleaning apparatus. Alternatively, the source material vaporization system 100 may supply a source gas at a predetermined concentration to a processing chamber of a semiconductor processing apparatus such as a CVD film formation apparatus or an MOCVD film formation apparatus.

[0023] This raw material vaporization system 100 introduces a carrier gas into a liquid or solid raw material, vaporizes it, and supplies the resulting mixed gas containing the raw material gas and the carrier gas. Note that, although an example using a liquid raw material will be described below, the same applies to a solid raw material.

[0024] Specifically, as shown in FIG. 1, the raw material vaporization system 100 includes a tank 2 that stores a liquid raw material LM, an inlet pipe 3 that introduces a carrier gas CG into the tank 2 to create bubbles, an outlet pipe 4 that discharges a mixed gas MG containing the carrier gas CG and a raw material gas formed by vaporizing the raw material LM from the tank 2, and a concentration measuring device 5 that measures the concentration of the raw material gas contained in the mixed gas MG.

[0025] The tank 2 is a sealed container made of, for example, stainless steel that contains the liquid raw material LM, and is heated to a constant temperature by a heating mechanism such as an external heater.

[0026] A supply source (not shown) of a carrier gas such as nitrogen or hydrogen is connected to the upstream side of the inlet pipe 3. The downstream side of the inlet pipe 3 is inserted into the tank 2. The downstream opening of the inlet pipe 3 is provided at a position lower than the liquid level of the liquid raw material LM contained in the tank 2, and the raw material LM is bubbled by the carrier gas CG introduced into the tank 2 from the inlet pipe 3. The inlet pipe 3 is also provided with a mass flow controller 6 that controls the flow rate of the raw material vaporization system 100. Specifically, the mass flow controller 6 controls the flow rate Q of the carrier gas CG supplied into the tank 2. ｃ and a CG mass flow controller 61 that controls the flow rate Q of the dilution gas DG that dilutes the mixed gas MG. ｄ and a DG mass flow controller 62 for controlling the

[0027] The upstream opening of the outlet pipe 4 is connected to an upper space (gas phase) formed in the tank 2 when the liquid raw material LM is contained therein. The downstream side of the outlet pipe 4 is connected to a chamber 200 of the semiconductor processing apparatus. Furthermore, a concentration measuring device 5 for measuring the concentration of the raw material gas contained in the mixed gas MG is provided downstream of the outlet pipe 4 and before reaching the chamber 200. The raw material gas concentration C measured by the concentration measuring device 5 is ｖ is sent to the MFC control unit 7 and the display control unit 8. The MFC control unit 7 ｖ and the target concentration C of the source gas Ｔ The display control unit 8 compares the measured concentration C of the source gas with the measured concentration C of the source gas and controls the mass flow controller 6. ｖ The measured concentration C of the raw material gas is output on a screen such as a display 81. ｖ A bypass pipe BP that bypasses the tank 2 is connected to the inlet pipe 3 and the outlet pipe 4, and the inlet pipe 3, the outlet pipe 4, and the bypass pipe BP are provided with flow path switching valves V1 to V3 that switch the flow path of the carrier gas CG between the tank 2 and the bypass pipe BP.

[0028] <2. Concentration Measuring Device> Next, the concentration measuring device 5 of this embodiment will be described.

[0029] As shown in FIG. 1, the concentration measuring device 5 includes a partial pressure sensor 51 for measuring the partial pressure of the raw material gas, a total pressure sensor 52 for measuring the total pressure of the mixed gas MG, and a total pressure signal P ｔ The delayed total pressure signal P ｔ a delay filter 53 that outputs a concentration C ｖ and a calculation unit 54 for calculating the

[0030] The partial pressure sensor 51 detects the partial pressure of the raw material gas and outputs a partial pressure signal P ｖSpecifically, the partial pressure sensor 51 is, for example, an NDIR sensor, and in order to obtain a sufficient S / N ratio, the detected partial pressure is subjected to processing such as moving average, and a partial pressure signal P indicating the partial pressure after the processing is output. ｖ As a result, the divided voltage signal P ｖ changes later than the pressure change when the pressure of the concentration measuring device 5 rises or falls, for example, when the chamber 200 is evacuated or when the supply of carrier gas starts. In this embodiment, the speed of evacuating the chamber 200 is 7.5 kPa / sec, but this is not limited to this.

[0031] The total pressure sensor 52 detects the pressure of the mixed gas MG and outputs a total pressure signal P ｔ Specifically, the total pressure sensor 52 is, for example, a CDG, and outputs a total pressure signal P ｔ is the voltage division signal P ｖ It changes without delay in response to the pressure change compared to the

[0032] The delay filter 53 receives the total pressure signal P ｔ The delayed total pressure signal P ｔ Specifically, the delay filter 53 outputs the total pressure signal P ｔ After that, the delay filter 53 performs a moving average process on the delayed total pressure signal P ｔ The delayed total pressure signal P ｔ ' indicates the total pressure signal P ｔ The change lags behind the pressure change.

[0033] The calculation unit 54 calculates the divided voltage signal P ｖ and delayed total pressure signal P ｔ Based on this, the concentration C of the source gas contained in the mixed gas MG ｖ Specifically, the calculation unit 54 calculates the delayed total pressure signal Pｔ ' to the voltage division signal P ｖ The concentration C of the source gas is the ratio of ｖ Thereafter, the calculation unit 54 calculates the calculated concentration C of the source gas. ｖ to the MFC control unit 7 and the display control unit 8.

[0034] Next, a comparison between the concentration measuring device 5 of this embodiment and a conventional concentration measuring device will be described with reference to FIGS.

[0035] In the concentration measuring device 5 of this embodiment, the delay filter 53 is ｔ Delayed total pressure signal P ｔ The delay filter 53 outputs the total pressure signal P ｔ The moving average interval of the detected partial pressure is set to be within the range of -37.5% to 37.5% of the moving average interval of the detected partial pressure. In other words, when the moving average interval of the detected partial pressure is set to, for example, 3.2 seconds, the total pressure signal P ｔ The moving average interval of the total pressure signal P is set to be within the range of ±1.2 seconds of the moving average interval of the detected partial pressure. ｔ It is desirable that the moving average interval of the detected partial pressure is within the range of -25% to 25% of the moving average interval of the detected partial pressure. In other words, when the moving average interval of the detected partial pressure is set to 3.2 seconds, the total pressure signal P ｔ The moving average interval of the total pressure signal P is preferably set to be within the range of ±0.8 seconds of the moving average interval of the detected partial pressure. ｔ The moving average interval of the delayed total pressure signal P ｔ Response speed of voltage division signal P ｖ 3, when the pressure on the downstream side of the concentration measuring device 5 drops, for example, when the chamber 200 is evacuated, no overshoot occurs. Note that the overshoot here is the difference between the response speed of the measured concentration C of the source gas output by the display control unit 8 and the response speed of the source gas. ｖ This means that the measured concentration C ｖThe sudden change in the concentration of the steady-state source gas C ｖ Compared with the apparent source gas concentration C ｖ However, this refers to a change of ±10% or more within 3 seconds, for example, but is not limited to this.

[0036] On the other hand, the conventional concentration measuring device does not have the delay filter 53, so as shown in FIG. ｖ Response speed and delay of total pressure signal P ｔ As a result, as shown in Figure 4, in the conventional concentration measuring device, an overshoot occurs when the pressure on the downstream side of the concentration measuring device drops, for example.

[0037] <Effects of this embodiment> According to the concentration measuring device 5 of this embodiment, the delay filter 53 ｔ For example, a moving average of the total pressure signal P ｔ The delayed total pressure signal P ｔ ', so the divided voltage signal P ｖ Response speed and delay of total pressure signal P ｔ As a result, when the pressure of the concentration measuring device 5 changes, such as when the pressure rises or falls, the difference in the response speed between the concentration C ｖ can be accurately measured.

[0038] The delay filter 53 also detects the total pressure signal P ｔ The moving average section of the total pressure signal P is set to be within the range of -37.5% to 37.5% of the moving average section of the detected partial pressure. ｔ The moving average interval of the delayed total pressure signal P ｔ Response speed of voltage division signal P ｖ Therefore, when the pressure on the downstream side of the concentration measuring device 5 drops, for example, when the chamber 200 is evacuated, the concentration C ｖAs a result, when the pressure on the downstream side of the concentration measuring device 5 drops, the concentration C ｖ This allows the source gas vaporization system 100 to measure the source gas concentration C ｖ Since the feedback control by the MFC control unit 7 can be stably performed based on the measured concentration C of the raw material gas, ｖ can be stably controlled.

[0039] Furthermore, the delay filter 53 in this embodiment is ｖ Response speed and delay of total pressure signal P ｔ The purpose of the lag filter 53 is to reduce the difference in response speed between the lag filter 53 and the response speed of the concentration measuring device 5'. Therefore, although the lag filter 53 has the effect of suppressing overshoot that occurs when the pressure on the downstream side of the concentration measuring device 5 drops, the effect of the lag filter 53 is not limited to this. Specifically, the lag filter 53 can suppress the output of a value lower than the actual measured value when the pressure on the upstream side of the concentration measuring device 5 rises, for example, when the supply of carrier gas starts.

[0040] Other Modified Embodiments The present invention is not limited to the above-described embodiments.

[0041] In this embodiment, the delay filter 53 is a filter for detecting the total pressure signal P ｔ However, the process of slowing down the response speed of the total pressure signal is not limited to the moving average. For example, the process of slowing down the response speed of the total pressure signal P ｔ The total pressure signal P to be output in the future ｔ Alternatively, a Kalman filter or the like may be used to predict the above.

[0042] Furthermore, although the lag filter 53 in this embodiment continuously performs processing to delay the response speed of the total pressure signal, it may alternatively perform processing to delay the response speed of the total pressure signal in a switchable manner. For example, a determination unit may be further provided that determines a pressure change, such as a rise or fall, in the concentration measuring device 5, and the determination unit determines whether to perform processing to delay the response speed of the total pressure signal. Specifically, if the determination unit determines that a pressure change, such as a rise or fall, in the concentration measuring device 5 is occurring, the lag filter 53 performs processing to delay the response speed of the total pressure signal. On the other hand, if the determination unit determines that such a change is not occurring, the lag filter 53 does not perform processing to delay the response speed of the total pressure signal. As a result, the lag filter 53 can switch between processing to delay the response speed of the total pressure signal depending on the determination of the determination unit, thereby limiting the period in which processing to delay the response speed of the total pressure signal is performed.

[0043] Furthermore, in this embodiment, the MFC control unit 7 and the display control unit 8 are not included in the concentration measuring device 5, but the MFC control unit 7 and the display control unit 8 may also be included in the concentration measuring device 5.

[0044] Furthermore, although the partial pressure sensor in this embodiment uses NDIR, the partial pressure sensor may use an infrared laser absorption method instead of NDIR, or may use a Fourier transform infrared spectroscopy (FTIR) method. Also, the wavelength of the partial pressure sensor is not limited to the infrared region.

[0045] Furthermore, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications are possible without departing from the spirit of the present invention.

[0046] According to the present invention, the concentration of a measurement target component contained in a gas can be accurately measured when the pressure of the concentration measuring device changes, such as when the pressure rises or falls.

[0047] REFERENCE SIGNS LIST 100: Raw material vaporization system 2: Tank 3: Inlet pipe 4: Outlet pipe 5: Concentration measuring device 51: Partial pressure sensor 52: Total pressure sensor 53: Delay filter 54: Calculation unit

Claims

1. A concentration measurement device for measuring a concentration of a measurement target component contained in a gas, comprising: a partial pressure sensor that detects a partial pressure of the measurement target component contained in the gas and outputs a partial pressure signal indicating the partial pressure; a total pressure sensor that detects a total pressure, which is the pressure of the gas, and outputs a total pressure signal indicative of the total pressure; a delay filter that performs processing to delay a response speed of the total pressure signal and outputs a delayed total pressure signal that is the total pressure signal after the processing; a calculation unit that calculates the concentration of the component to be measured contained in the gas based on the partial pressure signal and the delayed total pressure signal.

2. 2. The concentration measuring device according to claim 1, wherein the lag filter performs a moving average of the total pressure signal.

3. The partial pressure signal is outputted by taking a moving average of the detected partial pressure, 3. The concentration measuring device according to claim 2, wherein the lag filter is set so that the moving average section of the total pressure signal is within a range of -37.5% to 37.5% of the moving average section of the detected partial pressure.

4. 3. The concentration measuring device according to claim 1, wherein the partial pressure sensor is a non-dispersive infrared absorption sensor.

5. 3. The concentration measuring device according to claim 1, wherein the total pressure sensor uses a capacitance type diaphragm vacuum gauge.

6. The concentration measuring device according to claim 1 , further comprising a display control unit that outputs the concentration calculated by the calculation unit.

7. 1. A concentration measuring device used in a raw material vaporization system that introduces a carrier gas into a liquid or solid raw material contained in a tank to vaporize the raw material, and supplies a mixed gas containing the raw material gas and the carrier gas thus generated, a partial pressure sensor that detects a partial pressure, which is the pressure of the source gas, and outputs a partial pressure signal indicative of the partial pressure; a total pressure sensor that detects a total pressure within the tank and outputs a total pressure signal indicative of the total pressure; a delay filter that performs processing to delay a response speed of the total pressure signal and outputs a delayed total pressure signal that is the total pressure signal after the processing; a calculation unit that calculates the concentration of the source gas based on the partial pressure signal and the delayed total pressure signal.

8. A method for measuring a concentration of a component contained in a gas, comprising the steps of: Detecting a partial pressure of a component contained in the gas and outputting the partial pressure as a partial pressure signal; Detecting a total pressure, which is the pressure of the gas, and outputting the total pressure as a total pressure signal; A process is performed to delay the response speed of the total pressure signal, and a delayed total pressure signal is output as the total pressure signal after the process; A concentration measuring method for calculating the concentration of a component contained in the gas based on the partial pressure signal and the delayed total pressure signal.

9. 9. The concentration measurement method according to claim 8, which is used in a raw material vaporization system that introduces a carrier gas into a liquid or solid raw material contained in a tank to vaporize it, and supplies a mixed gas containing the resulting raw material gas and the carrier gas, and measures the concentration of the raw material gas.