Concentration measuring device

Abstract

Accurately measure the concentration of hydrogen peroxide gas. [Solution] The device comprises a measurement cell with a transparent window, a first sensor that measures the temperature of the gas and creates a first electrical signal, a second sensor that measures the pressure of the gas and creates a second electrical signal, a first light-receiving element that converts the amount of light having a predetermined wavelength that is incident on the gas through the transparent window into a fourth electrical signal, a second light-receiving element that receives the amount of light that has passed through the gas and exits from the transparent window and converts it into a fifth electrical signal, and a calculation unit that calculates the gas concentration based on the first electrical signal, the second electrical signal, the fourth electrical signal, and the fifth electrical signal.

Description

[Technical field]

[0001] The present invention relates to a concentration measuring device, and more particularly to a hydrogen peroxide gas concentration measuring device for accurately measuring the concentration of hydrogen peroxide gas. [Background technology]

[0002] First, the background of the use of hydrogen peroxide will be explained. Hydrogen peroxide gas is used for room temperature or low temperature sterilization in general industrial and medical fields where high temperature and high humidity heated steam sterilization cannot be used. In the sterilization field, sterilization using hydrogen peroxide gas has the advantages of being easy to handle, being easily soluble in water, and decomposing into non-toxic oxygen and water. However, hydrogen peroxide gas can corrode the object by condensing on the surface of the object. In addition, hydrogen peroxide gas is highly reactive and unstable, which can cause uneven concentration in the sterilization chamber, resulting in insufficient sterilization effects.

[0003] In the semiconductor manufacturing field, it is very important to control the concentration of oxidizers used in processes such as the formation of insulating oxide films that affect the performance of semiconductor devices during the production process. When hydrogen peroxide gas is used as an oxidizer, it has a high oxidizing power and is advantageous as an oxidizer, but because of its high reactivity, attenuation of the hydrogen peroxide gas concentration in the supply pipe from the hydrogen peroxide gas generation source to the film formation device becomes a problem. In particular, when hydrogen peroxide gas is supplied from one hydrogen peroxide generation device to multiple film formation devices in order to ensure production volume, the supply pipe lengths may differ due to physical layout constraints, and there are problems such as the hydrogen peroxide gas being decomposed before reaching the film formation device, resulting in variations in the concentration of hydrogen peroxide gas at the use point of each film formation device. For this reason, there is a demand for concentration control at the use point closest to each film formation device.

[0004] Next, we will explain the importance of concentration management. Hydrogen peroxide exists as a liquid under normal temperature and pressure conditions. To use hydrogen peroxide as a gas, it must be generated and transported under heated conditions. However, as mentioned above, hydrogen peroxide gas has high oxidizing power and high reactivity, making it unstable, and if its temperature rises too much, it will decompose, which is a problem. Therefore, when using hydrogen peroxide gas, temperature management and concentration measurement are very important.

[0005] A conventional technique for measuring hydrogen peroxide gas concentration is described below. To measure the hydrogen peroxide gas concentration in a hydrogen peroxide gas fluid having a temperature of 100-200°C and a concentration of 5,000-20,000 ppm, a measuring device is known which includes a sampling path branching off from a hydrogen peroxide gas transport pipe, a catalyst case containing a hydrogen peroxide decomposition catalyst layer which is placed immediately adjacent to the transport pipe side of the sampling path, gas temperature measuring devices disposed on the gas inlet and outlet sides of the catalyst case, and a calculation device which calculates the hydrogen peroxide gas concentration from the temperature difference between the gas inlet and outlet sides (see, for example, Patent Document 1 (pages 5-7)).

[0006] Also, in order to determine the concentration of hydrogen peroxide vapor or gas within a certain storage area, a concentration determination method is known which comprises the steps of evacuating the storage area, introducing hydrogen peroxide into the storage area to form a sample, measuring the absorbance of the sample at wavelengths between 200 nanometers and 400 nanometers, and determining the concentration of hydrogen peroxide vapor or gas in the sample from the absorbance (see, for example, Patent Document 2 (pages 3-4)).

[0007] Patent documents 1 and 2 employ a method for measuring the hydrogen peroxide gas concentration from the heat of reaction of hydrogen peroxide with a catalyst, or a method for measuring the hydrogen peroxide gas concentration from the absorbance at wavelengths between 200 nanometers and 400 nanometers. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2014-020826 A [Patent Document 2] Japanese Patent Application Publication No. 11-230899 Summary of the Invention [Problem to be solved by the invention]

[0009] However, when used for sterilization or disinfection, hydrogen peroxide gas does not disperse evenly within the treatment chamber, and the target concentration of hydrogen peroxide gas does not reach the vicinity of the object to be sterilized or disinfected, resulting in the failure to achieve the desired sterilization or disinfection effect.

[0010] In addition, concentration control of oxidizers used in processes such as the formation of insulating oxide films that affect the performance of semiconductor devices during the production process is very important. When hydrogen peroxide gas is used as an oxidizer, it has a high oxidizing power and is advantageous as an oxidizer, but its high reactivity causes a problem of attenuation in the supply pipes from the hydrogen peroxide source to the film formation equipment. In particular, when hydrogen peroxide gas is supplied from one hydrogen peroxide generation device to multiple film formation devices in order to ensure production volume, the supply pipe lengths may differ due to physical layout constraints. For this reason, there is a demand for concentration control at the use point closest to each film formation device, but there was a problem that the conventional technology could not meet this demand.

[0011] Furthermore, as mentioned above, hydrogen peroxide gas is unstable due to its high oxidizing power and high reactivity, and will decompose if its temperature rises too high. Therefore, temperature control and concentration measurement are extremely important when using hydrogen peroxide gas, but conventional technology had the problem of not being able to control the temperature and measure the concentration.

[0012] The present invention has been made in consideration of such problems, and an object of the present invention is to provide a concentration measurement device for accurately measuring hydrogen peroxide gas concentration by measuring the absorbance, temperature, and pressure of hydrogen peroxide gas. [Means for solving the problem]

[0013] A concentration measuring device according to one embodiment of the present invention includes a measurement cell through which hydrogen peroxide gas flows, a first sensor that measures the temperature of the hydrogen peroxide gas to generate a first electrical signal, a second sensor that measures the pressure of the hydrogen peroxide gas to generate a second electrical signal, a third sensor that measures the temperature of the temperature block to generate a third electrical signal, and a temperature-constant block having a heater that heats the temperature-constant block, a heat insulating material that encompasses the temperature-constant block, a light source that emits light at a wavelength for measuring the concentration of hydrogen peroxide gas, and a detector that converts the amount of light emitted by the light source into a fourth electrical signal. the first light-receiving element converting the amount of light transmitted through the hydrogen peroxide gas circulating in the measurement cell into a fifth electrical signal; a distributor branching the light emitted by the light source into light directed to the first light-receiving element and light directed to the second light-receiving element; and an embedded system provided outside the thermal insulation material, the embedded system including: a control unit controlling the heater based on the third electrical signal; and a calculation unit calculating the concentration of the hydrogen peroxide gas based on the first electrical signal, the second electrical signal, the fourth electrical signal, and the fifth electrical signal.

[0014] According to this configuration, it is possible to accurately measure the hydrogen peroxide gas concentration while maintaining a predetermined temperature.

[0015] Another aspect of the present invention is a measurement cell suitable for the concentration measuring device of one aspect of the present invention. The measurement cell of this aspect includes a first cell block that houses a measurement gas flow path for flowing hydrogen peroxide gas into the measurement cell, a first transmission window through which light enters the measurement cell, a cell spacer that determines the optical path length, and a second transmission window through which light not absorbed by the hydrogen peroxide gas that has flowed into the measurement cell exits, a second cell block that sandwiches the first transmission window, the cell spacer, and the second transmission window with the first cell block, a first O-ring disposed between the first transmission window and the second cell block, and a second O-ring disposed between the second transmission window and the first cell block.

[0016] With a measurement cell of this configuration, it is possible to prevent a decrease in the airtightness of the measurement cell due to deterioration of the measurement cell caused by temperature changes outside the measurement cell, pressure fluctuations in the measurement gas, or reactions between the measurement cell and the measurement gas, and it is possible to accurately measure the hydrogen peroxide gas concentration.

[0017] A concentration measuring device according to one embodiment of the present invention includes a measurement cell through which a gas flows and which has a transmission window, a first sensor which measures the temperature of the gas and creates a first electrical signal, a second sensor which measures the pressure of the gas and creates a second electrical signal, a first light receiving element which converts an amount of light having a predetermined wavelength which is incident on the gas through the transmission window into a fourth electrical signal, a second light receiving element which receives an amount of light which has passed through the gas and exits through the transmission window and converts it into a fifth electrical signal, and a built-in system which calculates a gas concentration according to Beer-Lambert's law based on the first electrical signal, the second electrical signal, the fourth electrical signal, and the fifth electrical signal.

[0018] According to this configuration, it is possible to accurately measure the hydrogen peroxide gas concentration. Effect of the Invention

[0019] According to the present invention, it is possible to provide a concentration measuring device and a measurement cell capable of accurately measuring hydrogen peroxide gas concentration. This enables proper concentration control for obtaining a sterilization or disinfection effect, which was not possible with conventional technology, and concentration control at the point of use immediately adjacent to each film forming device, thereby enabling strict control of the hydrogen peroxide gas concentration required for sterilization or disinfection treatment or film formation in semiconductor manufacturing processes. [Brief description of the drawings]

[0020] [Figure 1] 1 is a schematic diagram illustrating a concentration measuring device according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a front view of an insulator-covered thermostatic block according to one embodiment of the present invention (front insulation not shown). [Diagram 3]FIG. 2 is a side view of a measurement cell according to one embodiment of the present invention. [Figure 4] FIG. 1 is a schematic diagram illustrating a cross section of a conventional measurement cell. [Diagram 5] FIG. 2 is a schematic diagram illustrating a cross section of a measurement cell according to one embodiment of the present invention. [Figure 6] FIG. 2 is a schematic diagram illustrating a cross section of a measurement cell according to one embodiment of the present invention. [Figure 7] 4 is a flowchart of a process of a concentration measuring device according to an aspect of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described in detail with reference to the drawings, in which like reference numerals represent like elements, with reference to the accompanying drawings, in which: FIG.

[0022] The concentration measuring device of the present invention utilizes the property of hydrogen peroxide gas absorbing ultraviolet light and measures the concentration according to Beer's Lambert law from the rate at which hydrogen peroxide gas absorbs ultraviolet light in a measuring cell.

[0023] In particular, when measuring hydrogen peroxide gas, the temperature must be kept high (for example, between 90°C and 200°C, e.g., 120°C) to prevent the hydrogen peroxide gas from condensing, and the measurement cell is heated to a high temperature. Also, because the high-temperature measurement cell and the concentration calculation circuit formed from semiconductor components coexist inside the concentration measuring device of the present invention, it is necessary to thermally insulate the semiconductor circuit, and thermal isolation and insulation are performed for the electronic circuit. Furthermore, because the atmosphere of the measurement environment differs depending on the process and the temperature or pressure changes, pressure and temperature correction is required to display the hydrogen peroxide concentration under standard conditions, and the concentration is displayed under standard conditions.

[0024] To keep the temperature of the measurement cell constant at high temperatures, the measurement cell is covered with a thermally conductive material (such as aluminum) to form a thermostatic block, which is heated with a heater and feedback controlled by a control temperature sensor.

[0025] The thermal isolation and insulation of the electronic circuit will be explained. The ultraviolet light source, incident light detector, transmitted light detector amplifier circuit, control unit, and calculation unit are composed of semiconductor parts, and the upper limit temperature of the general-purpose parts is about 80°C. For this reason, it is necessary to transmit the light for measuring the absorption of ultraviolet light and prevent heat conduction from the temperature-controlled block, which becomes hot, and heat conduction by radiation. As a countermeasure, a heat insulating material is applied to the entire outer periphery of the temperature-controlled block except for the light transmission path, and a structure is created in which the temperature-controlled block is kept warm and heat transfer to the outside is prevented. In addition, an exhaust port is provided at the top of the housing, and an air intake port is provided at the bottom along the periphery of the insulation surrounding the temperature-controlled block to prevent air stagnation and provide a thermal insulation layer of air to block heat conduction from the high-temperature part. A ventilation fan may be provided at the exhaust port.

[0026] The concentration display under standard conditions will now be explained. In order to always display the hydrogen peroxide concentration under standard conditions even if the temperature or pressure of the hydrogen peroxide gas changes due to differences in the atmosphere of the hydrogen peroxide gas measurement environment depending on the process, a correction temperature sensor and pressure sensor are provided to measure the pressure and temperature of the hydrogen peroxide gas in the piping in the measurement gas flow path, and pressure and temperature correction is performed according to Lambert-Beer's law to always display the hydrogen peroxide concentration under standard conditions of 0°C and 1 atmosphere. The standard condition is merely one example, and the condition for comparison with the changed temperature or pressure does not necessarily have to be the standard condition; other temperatures or pressures may be used as long as they are under the same conditions and can be compared with the changed temperature or pressure.

[0027] 1 is a schematic diagram illustrating a concentration measurement device according to an embodiment of the present invention. For the purpose of explanation, the concentration measurement device 100 according to an embodiment of the present invention is located between, for example, a hydrogen peroxide gas supply device (not shown) that generates hydrogen peroxide gas and, for example, a semiconductor manufacturing device (not shown) that uses the generated hydrogen peroxide gas. The concentration measurement device 100 measures the absorbance of hydrogen peroxide gas and continuously measures the hydrogen peroxide gas concentration by applying the Beer-Lambert law to the measured absorbance.

[0028] The concentration measuring device 100 has a measurement cell 101 attached inside the concentration measuring device 100. The measurement cell 101 is used to measure the absorbance of hydrogen peroxide gas flowing inside the measurement cell 101. The concentration measuring device 100 has a measurement gas flow path 102a attached to the measurement cell 101 for allowing hydrogen peroxide gas from a hydrogen peroxide gas supply device (not shown) outside the concentration measuring device 100 to flow into the measurement cell 101. The concentration measuring device 100 also has a measurement gas flow path 102b attached to the measurement cell 101 for allowing the hydrogen peroxide gas flowing from the measurement gas flow path 102a to flow out to a semiconductor manufacturing device (not shown) outside the concentration measuring device 100. The concentration measuring device 100 has a temperature sensor 103 (also referred to as a first sensor) attached to either the measurement cell 101, the measurement gas flow path 102a, or 102b for measuring the temperature of the hydrogen peroxide gas flowing through the measurement cell 101, the measurement gas flow path 102a, and 102b. The concentration measuring device 100 has a pressure sensor 104 (also referred to as a second sensor) attached to either the measurement cell 101, the measurement gas flow path 102a, or 102b, and measures the pressure of the hydrogen peroxide gas flowing through the measurement cell 101, the measurement gas flow path 102a, and 102b.

[0029] 1, temperature sensor 103 is attached to measurement gas flow path 102a, but temperature sensor 1031, which is an alternative to temperature sensor 103, may be attached to thermostatic block 105, which will be described next. Also, pressure sensor 104 is attached to measurement gas flow path 102a in Fig. 1, but pressure sensor 1041 or pressure sensor 1042, which is an alternative to pressure sensor 104, may be attached to a pipe from a hydrogen peroxide gas supply device (not shown) to concentration measurement device 100 or to a pipe from concentration measurement device 100 to a semiconductor manufacturing device (not shown). The positions of temperature sensor 103 and pressure sensor 104 are not limited to those shown in Fig. 1.

[0030] The concentration measuring device 100 has a constant temperature block 105 that contains the measurement cell 101 and keeps the temperature of the measurement cell 101 constant inside the concentration measuring device 100. The concentration measuring device 100 has a temperature sensor 106 (also called a third sensor) that is attached to the outside of the constant temperature block 105 inside the concentration measuring device 100 and measures the temperature of the constant temperature block 105. The concentration measuring device 100 has a heater 107 (also called a warmer) that is attached to the outside of the constant temperature block 105 inside the concentration measuring device 100 and heats the hydrogen peroxide gas passing through the inside of the measurement cell 101 so as to keep the temperature constant. The positions of the temperature sensor 106 and the heater 107 are directly attached to the constant temperature block to heat the constant temperature block and measure its temperature, and may be different from the positions of the temperature sensor 106 and the heater 107 shown in FIG. 1 as long as they are directly attached to the constant temperature block to heat the constant temperature block and measure its temperature.

[0031] The concentration measuring device 100 has a heat insulating material 108 that is attached to cover the entire constant temperature block 105 including the heater 107 inside the concentration measuring device 100 and blocks heat radiation from the constant temperature block 105 and keeps the inside of the measurement cell 101 warm. The heat insulating material 108 prevents the heat of the heater 107 from being transferred to surrounding electronic circuits.

[0032] The concentration measuring device 100 has a light source lamp 109 (also called a light source) that is attached inside the concentration measuring device 100 and emits light of a wavelength required for measuring the absorbance of hydrogen peroxide gas. The concentration measuring device 100 has a transmission window 110a that is attached to the measurement cell 101 and transmits the light emitted by the light source lamp and allows it to enter the measurement cell 101. The concentration measuring device 100 also has a transmission window 110b that is attached to the measurement cell 101 and allows the light that has transmitted through the hydrogen peroxide gas to exit the measurement cell 101. Note that the transmission windows 110a and 110b are not necessarily required as long as the measurement cell 101 itself is made of a material that transmits light of a wavelength in the absorption band of hydrogen peroxide, such as glass. The concentration measuring device 100 has a light distributor 113 (also called a distributor) that is attached inside the concentration measuring device 100 and reflects part of the light emitted by the light source lamp 109 and transmits part of it. The concentration measuring device 100 has a light receiving element 111 (also referred to as a first light receiving element) that is attached inside the concentration measuring device 100 and converts the light reflected by the light distributor 113 into an electrical signal (also referred to as a fourth electrical signal), and a light receiving element 112 (also referred to as a second light receiving element) that is attached inside the concentration measuring device 100 and converts the light that has passed through the light distributor 113 and the hydrogen peroxide gas flowing in from the measurement gas flow path 102a into an electrical signal (also referred to as a fifth electrical signal).

[0033] Concentration measuring device 100 has control unit 114 that controls the temperature of constant temperature block 105 outside heat insulating material 108, and calculation unit 115 that calculates the hydrogen peroxide gas concentration. Concentration measuring device 100 has air intakes 117a and 117b that are opened in housing 116 of concentration measuring device 100 and allow outside air to flow into concentration measuring device 100. Concentration measuring device 100 has exhaust port 118 that is opened in housing 116 of concentration measuring device 100 and exhausts air from inside concentration measuring device 100. Note that exhaust port 118 may have a ventilation fan.

[0034] The cooling area 121 represents an area inside the concentration measuring device 100 where outside air flows in through the air intakes 117a and 117b and flows out through the exhaust port 118 for ventilation, and where heat from the constant temperature block 105 is insulated by the insulating material 108, resulting in a temperature lower than that of the constant temperature block 105. The heat retention area 122 represents an area inside the constant temperature block 105 that is heated by the heater 107 and is kept warm and insulated by the insulating material 108.

[0035] Arrow 131 indicates the direction of travel of light that is emitted from light source lamp 109, passes through light distributor 113, and enters hydrogen peroxide gas flowing in from measurement gas flow path 102a. Arrow 132 indicates the direction of travel of light that is emitted from light source lamp 109, reflected by light distributor 113, and enters light receiving element 111.

[0036] Arrow 141a represents the flow of hydrogen peroxide gas flowing from a hydrogen peroxide gas supply device (not shown) outside concentration measurement device 100 into the inside of concentration measurement device 100. Arrow 141b represents the flow of hydrogen peroxide gas flowing from the inside of concentration measurement device 100 to a semiconductor manufacturing device (not shown) outside concentration measurement device 100.

[0037] Next, a description will be given of calculations for determining the hydrogen peroxide gas concentration by concentration measuring apparatus 100. Hydrogen peroxide gas supplied by a hydrogen peroxide gas supply apparatus (not shown) flows into measurement cell 101 via measurement gas flow path 102a, for example, by pressurized air supply or suction. The hydrogen peroxide gas that has flowed into measurement cell 101 flows inside measurement cell 101 and is supplied to a semiconductor manufacturing apparatus (not shown) via measurement gas flow path 102b.

[0038] While hydrogen peroxide gas flows inside measurement cell 101, light (indicated by arrow 131) emitted by light source lamp 109 and transmitted through light distributor 113 enters transmission window 110a, and only the light that is absorbed by the hydrogen peroxide gas and then transmitted is received by light receiving element 112 and converted into a fifth electrical signal. The converted electrical signal is sent to calculation unit 115.

[0039] Furthermore, the light emitted by light source lamp 109 and reflected by light distributor 113 is received by light receiving element 111 and converted into a fourth electrical signal, and the converted electrical signal is transmitted to calculation unit 115. Since the amount of light from light source 109 is not always constant, the light reflected by light distributor 113 is measured by light receiving element 111, and the measurement result of the light transmitted through the optical cell is measured by light receiving element 112, and the fluctuation in the amount of light is corrected, thereby making it possible to measure the absorbance due purely to the absorption of light by hydrogen peroxide.

[0040] The temperature of the hydrogen peroxide gas is maintained at, for example, between 90° C. and 200° C., for example, at 120° C., by heater 107 so that the hydrogen peroxide gas does not decompose or condense while it flows inside measurement cell 101. Heater 107 is controlled by control unit 114 and temperature sensor 106 so that the heat-insulating cell block maintains a constant temperature, thereby maintaining a constant temperature condition.

[0041] While the hydrogen peroxide gas flows inside measurement cell 101, the temperature and pressure are accurately measured by temperature sensor 103 and pressure sensor 104, respectively, and the measured data (also referred to as a first electrical signal and a second electrical signal, respectively) are transmitted to calculation unit 115. Using the electrical signals from light receiving elements 111, 112 and the data from temperature sensor 103 and pressure sensor 104, calculation unit 115 calculates the hydrogen peroxide gas concentration according to the following formula (1). C=A / αT*log(Io / Ix)*(273+t) / 273*Po / (P+Po) (1) however, C: Desired hydrogen peroxide gas concentration, A: A constant specific to the device. α: ultraviolet absorption coefficient of hydrogen peroxide gas, T: optical path length (optical path length representing the distance that the light emitted from the light source lamp 109 passes through the hydrogen peroxide gas inside the measurement cell 101), Io: the amount of light incident on the measurement cell 101, Ix: the amount of light transmitted through the measuring cell 101; t: temperature of hydrogen peroxide gas, Po: 1 atmosphere, P: Hydrogen peroxide gas pressure Log (Io / Ix) represents absorbance. The relationship between the amount of light measured by each light receiving element and absorbance is as follows:

[0042] In order to measure the incident light and transmitted light in the Beer-Lambert law, first, a standard gas that does not contain hydrogen peroxide is passed through the measurement cell (in FIG. 1, the source of the standard gas and the switching valve for switching are not shown for the sake of simplicity of the drawing). The amount of light measured by the light-receiving element 111 for the passed standard gas is S11, and the amount of light measured by the light-receiving element 112 at the same time is S21. S11 and S21 are stored in a storage device.

[0043] Next, hydrogen peroxide gas to be measured is passed through the measurement cell. The light intensities measured by light receiving elements 111 and 112 for the passed hydrogen peroxide gas are designated as S12 and S22, respectively. Here, S21 measured when no hydrogen peroxide is present is taken as the incident light in formula (1), and then the change in S11 to S12 measured by light receiving element 111 (fluctuation in the light intensity of the light source) is corrected for S22 after the passage of hydrogen peroxide gas, thereby enabling absorbance measurement using hydrogen peroxide gas without the influence of fluctuations in the light intensity of the light source. The formula for calculating absorbance: log(Io / Ix) is as follows: log(Io / Ix)=log((S21 / (S22×S11 / S12))...(2) By substituting the absorbance calculated using equation (2) into the Beer-Lambert equation (1), it is possible to accurately measure the hydrogen peroxide gas concentration without being affected by fluctuations in the light source.

[0044] By repeating the above steps, continuous measurements are possible.

[0045] As an example, the measurement cell 101 may have a housing made of a metal material. The metal material may be, for example, stainless steel. Details of the measurement cell 101 will be described below with reference to Figs. 3 to 5. The measurement gas flow paths 102a and 102b need to be made of a material that is resistant to corrosion by highly reactive hydrogen peroxide gas and that does not easily decompose hydrogen peroxide.

[0046] The measurement gas flow paths 102a, 102b may be made of, for example, a fluororesin. The fluororesin may be, for example, a perfluoroalkoxyalkane (PFA) resin or a similar material suitable for carrying a gas whose concentration is to be measured. The measurement gas flow paths 102a and 102b may be the same or different. The measurement gas flow paths 102a, 102b may be an integrated flow path. The measurement gas flow paths 102a, 102b may be made of, for example, glass.

[0047] The temperature sensor 103 measures t in the above-described formula (1). The temperature sensors 103 and 106 may be, for example, platinum resistance temperature detectors. The temperature sensors 103 and 106 may also be, for example, copper resistance temperature detectors.

[0048] The pressure sensor 104 may be, for example, a strain gauge pressure sensor, or may be, for example, a piezoelectric pressure sensor, a silicon pressure sensor, or the like.

[0049] The heater 107 is a heater, which may be, for example, a resistive heater.

[0050] The heat insulating material 108 may be, for example, melamine. As an example, melamine is a thermosetting foam material having open or closed cells, and has excellent flame retardancy, heat resistance, and heat insulation properties. The heat insulating material 108 may be a heat insulating material having a heat resistance of 120° C. or more.

[0051] The light source lamp 109 may be, for example, an excimer lamp, or may be, for example, an LED, a mercury lamp, a deuterium lamp, a zinc lamp, a cadmium lamp, or the like suitable for emitting light of a wavelength (e.g., 200 to 400 nm, etc.) that covers the absorption band of hydrogen peroxide.

[0052] The transmissive windows 110a, 110b may be, for example, quartz glass, or may be, for example, sapphire glass or the like suitable for transmitting light of wavelengths in the absorption band of hydrogen peroxide gas.

[0053] The light receiving elements 111 and 112 may be, for example, photodiodes, or may be, for example, phototubes, photomultiplier tubes, silicon photodiodes, or the like that are sensitive to the absorption band of hydrogen peroxide.

[0054] The optical distributor 113 is, by way of example, fused silica, which may be coated, by way of example, with metal oxide, aluminum, nickel chrome, or the like, to control the transmittance and reflectance.

[0055] The control unit 114 and the calculation unit 115 may be included in an embedded system 120 including, for example, a microcontroller (MCU: Micro-Control Unit). The embedded system 120 described above is composed of, for example, a semiconductor integrated circuit including a processor and a memory, and executes a computer program including, for example, an operating system and application software stored in, for example, a memory. The processor described above may be a general-purpose processor including, for example, an MPU (Micro-Phase Processing Unit), a CPU (Central Processing Unit), and the like. The memory described above may be a storage device including, for example, a ROM (Read Only Memory), a PROM (Programmable ROM), an EPROM (Erasable Programmable ROM), an EEPROM (Electrically EPROM), a RAM (Random-Access Memory), a DRAM (Dynamic RAM), a SRAM (Static RAM), and the like.

[0056] The control unit 114 receives data (also referred to as a third electrical signal) relating to the temperature of the constant temperature block 105 measured by the temperature sensor 106. If the temperature indicated by the received data is lower than a preset temperature, the control unit 114 starts energizing the heater 107 to heat the constant temperature block 105. If the temperature indicated by the received data is higher than the preset temperature, the control unit 114 stops energizing the heater 107. The operation of the calculation unit 115 will be described in detail with reference to FIG. 7.

[0057] The housing 116 may be made of a metal material, for example, stainless steel.

[0058] The intake ports 117a and 117b can allow the outside air of the concentration measuring device 100 to flow into the inside of the concentration measuring device 100. The intake ports 117a and 117b have a position and shape suitable for allowing the outside air to flow into the inside of the concentration measuring device 100 for thermal insulation between the constant temperature block 105 and the electronic circuit including the control unit 114 and the calculation unit 115. The intake ports 117a and 117b may have various shapes, such as a slit. Note that, for example, when the exhaust port 118 has a ventilation fan, the intake ports 117a and 117b can force the outside air of the concentration measuring device 100 to flow into the inside of the concentration measuring device 100 by the ventilation fan.

[0059] Exhaust port 118 may have a ventilation fan, such as a cooler fan, suitable for drawing air outside concentration measuring device 100 into the interior of concentration measuring device 100 and drawing air inside concentration measuring device 100 out to the outside.

[0060] All of the above are for illustrative purposes and are not limiting.

[0061] Fig. 2 is a front view of a thermostatic block 105 having a measurement cell 101 inside covered with a thermal insulation material 108 according to one embodiment of the present invention, and the thermal insulation material 108 on the front side is not shown in Fig. 2. In Fig. 2, the thermostatic block 105 includes the temperature sensors 103, 106, and heater 107 described with reference to Fig. 1. The positions of the temperature sensors 103, 106, and heater 107 shown in Fig. 2 are different from the positions of the temperature sensors 103, 106, and heater 107 shown in Fig. 1, as long as the temperature sensors have their temperature-sensing parts directly attached to the surface of the thermostatic block, and the heaters have their heat-generating surfaces directly attached to the surface of the thermostatic block.

[0062] Fig. 3 is a side view of a measurement cell 101 according to one embodiment of the present invention. The measurement cell 101 is incorporated in a thermostatic block 105. In Fig. 3, the measurement cell 101 has the measurement gas flow paths 102a and 102b and the transmission window 110b described with reference to Fig. 1. The measurement cell 101 has a fixing plate 505a and fixing screws 506a and 506b, which will be described later with reference to Fig. 5.

[0063] 4 is a schematic diagram illustrating a cross section of a conventional measurement cell 400. Arrows 431 indicate the direction in which light emitted from a light source lamp (not shown) travels to enter the measurement gas flowing in from measurement gas flow passage 421.

[0064] The conventional measurement cell 400 is constructed by storing a conventional transmission window 410b, a conventional cell spacer 403 that determines the optical path length indicated by an arrow 411, and a conventional transmission window 410a, in that order, inside a receiving conventional cell block 401, and sandwiching them with a cover conventional cell block 402, and the conventional cell blocks 401 and 402 are fixed by fixing plates 405a and 405b fixed by fixing screws 406a and 406b, as illustrated in Fig. 4. The flow path of the measurement gas is sealed by disposing O-rings 404b and 404a between the conventional transmission windows 410b and 410a and the conventional cell blocks 401 and 402, respectively.

[0065] However, in the conventional measurement cell 400, the gap between the cell block and the transmission window is sealed only by an O-ring, and therefore there are problems such as the elastic deterioration of the O-rings 404a and 404b causing a loss of airtightness due to changes in the external temperature, pressure fluctuations of the measurement gas, deterioration due to reactions with the measurement gas, and the like.

[0066] The inventors of the present application have newly developed a measurement cell 101 according to one embodiment of the present invention, and have succeeded in solving the problems of the O-rings 404a and 404b losing their airtightness due to elastic deterioration. Next, the structure of the measurement cell 101 of the present invention will be described with reference to FIG. 5.

[0067] FIG. 5 is a schematic diagram illustrating a cross section of a measurement cell 101 according to one embodiment of the present invention.

[0068] The measurement cell 101 according to one embodiment of the present invention has a structure in which a transmission window 110b, a cell spacer 503 that determines the optical path length indicated by an arrow 511, and a transmission window 110a are stored in that order inside a receiving cell block 501, and are sandwiched between a cover cell block 502. The measurement cell 101 has a structure in which the flow path of the measurement gas is sealed by placing O-rings 504b and 504a between the transmission windows 110b and 110a and the cell blocks 501 and 502, respectively.

[0069] The measurement cell 101 according to one embodiment of the present invention includes the measurement gas flow path 102a and the transmission window 110a (also referred to as the first transmission window) and the transmission window 110b (also referred to as the second transmission window) described with reference to FIG. 1, and the cell block 501 (also referred to as the first cell block) and the cell block 502 (also referred to as the second cell block) described later. The measurement cell 101 includes a cell spacer 503 that determines the optical path length indicated by an arrow 511. The measurement cell 101 includes an O-ring 504a (also referred to as the first O-ring) that is disposed between the cell block 502 and the transmission window 110a, and an O-ring 504b (also referred to as the second O-ring) that is disposed between the cell block 501 and the transmission window 110b. The measurement cell 101 includes fixing plates 505a and 505b that are disposed so as to sandwich the cell block 501 and the cell block 502 and are fixed by fixing screws 506a and 506b. The measurement cell 101 has gap spacers 507a and 507b that maintain a constant distance between the fixed plate 505a and the fixed plate 505b.

[0070] Cell block 501 is a receiving cell block, and contains transmission window 110b, cell spacer 503, and transmission window 110a, in that order, inside cell block 501. Cell block 502 serves as a cover, and has a structure in which cell block 501 and cell block 502 sandwich transmission window 110a, cell spacer 503, and transmission window 110b. The flow path of the measurement gas is sealed by placing O-ring 504b between cell block 501 and transmission window 110b, and O-ring 504a between cell block 502 and transmission window 110a.

[0071] In the measurement cell 101 according to one embodiment of the present invention illustrated in FIG. 5, the circular corners of the transmission windows 110a and 110b are C-faced, the cell spacer 503 is made of an elastically deformable resin such as PTFE or PFA, and the opposing surfaces of the transmission windows 110a and 110b are also inclined along their circumferences. The fixing plates 505a and 505b are made of metal and are configured to sandwich the cell blocks 501 and 502, and are fixed by fixing screws 506a and 506b. The gap spacers 507a and 507b are made of metal and are inserted between the fixing plates 505a and 505b so that the distance between the fixing plates 505a and 505b is constant. When fixing plates 505a and 505b are fastened together, cell spacer 503 is deformed and fastened within the elastic deformation condition where cell spacer 503 does not buckle the fastening margin due to the length of gap spacers 507a and 507b and the length of cell spacer 503. By deforming and fastening cell spacer 503, it is possible to maintain the sealability between transmission windows 110a and 110b and cell spacer 503, and at the same time, to maintain a constant optical path length indicated by arrow 511 between transmission windows 110a and 110b.

[0072] With this configuration, in addition to the seal structure formed by the O-rings 504a and 504b, the cell spacer 503 can form a new seal structure at the contact surface between the transmission windows 110a and 110b and the cell spacer 503. At the same time as forming the new seal structure, it becomes possible to manage the distance between the transmission windows 110a and 110b by managing the cell spacer 503, which is very important in measuring the absorbance of the measurement gas.

[0073] The O-rings 504a and 504b are, for example, made of fluororubber, and form the seal structure of the present invention. For example, the fluororubber does not buckle and has excellent corrosion resistance.

[0074] Arrow 511 indicates the optical path length for measuring the ultraviolet light absorbance of hydrogen peroxide gas, and corresponds to T in formula (1) described with reference to FIG. 1. The optical path length is the distance between transmission windows 110a and 110b. A portion of the light transmitted through transmission window 110a is absorbed by hydrogen peroxide gas. The light not absorbed by hydrogen peroxide gas transmits through transmission window 110b. The light transmitted through transmission window 110b is received by light receiving element 112 shown in FIG. 1.

[0075] 6 is a schematic diagram illustrating another cross section of the measurement cell 101 according to one embodiment of the present invention. Light emitted by the light source lamp 109 (indicated by the arrow 131) passes through the portion indicated by the reference numeral 601.

[0076] 7 is a flowchart of the process of the concentration measuring device 100 according to one embodiment of the present invention. The process of the concentration measuring device 100 according to one embodiment of the present invention starts when the power of the concentration measuring device 100 is turned on.

[0077] 1 turns on the light source lamp 109. The embedded system 120 also starts controlling the heater based on data (third electrical signal) related to the temperature of the constant temperature block 105 measured by the temperature sensor 106. The process proceeds to step S702.

[0078] In step S702, a standard gas is caused to flow from a standard gas generation source (not shown) through a measurement gas flow path 102a into the measurement cell 101. The process proceeds to step S703.

[0079] In step S703, the light from light source lamp 109 turned on in step S701 is reflected by optical distributor 113, and the light is received by light receiving element 111 and converted into an electrical signal, which is received by calculation unit 115. The amount of light (S11) indicated by the received electrical signal is temporarily stored in a storage device within calculation unit 115, and is then used when calculating the hydrogen peroxide gas concentration within calculation unit 115 in step S710, which will be described below. The process proceeds to step S704.

[0080] In step S704, the light from light source lamp 109 turned on in step S701 passes through light distributor 113, the transmitted light is absorbed by the standard gas, and the light is received by light receiving element 112 and converted into an electrical signal which is received by calculation unit 115. As in step S703, the amount of light (S21) indicated by the received electrical signal is temporarily stored in a storage device within calculation unit 115, and is then used when calculating the hydrogen peroxide gas concentration within calculation unit 115 in step S710, which will be described below. The process then proceeds to step S705.

[0081] In step S705, the standard gas is switched to hydrogen peroxide gas by a switching valve (not shown), and hydrogen peroxide gas is caused to flow from the measurement gas flow path 102a into the measurement cell 101. The process proceeds to step S706.

[0082] In step S706, the light from light source lamp 109 turned on in step S701 is reflected by optical distributor 113, and the reflected light is received by light receiving element 111 and converted into an electrical signal (fourth electrical signal) which is received by calculation unit 115. As in steps S703 and S704, the amount of light (S12) indicated by the received electrical signal is temporarily stored in a storage device within calculation unit 115, and is then used when calculating the hydrogen peroxide gas concentration within calculation unit 115 in step S710 described below. The process then proceeds to step S707.

[0083] In step S707, the light from light source lamp 109 turned on in step S701 passes through light distributor 113, the transmitted light is absorbed by hydrogen peroxide gas, and the light is received and converted by light receiving element 112 into an electrical signal (fifth electrical signal) which is received by calculation unit 115. As in steps S703, S704, and S706, the amount of light (S22) indicated by the received electrical signal is temporarily stored in a storage device within calculation unit 115, and is then used when calculating the hydrogen peroxide gas concentration within calculation unit 115 in step S710 described below. The process then proceeds to step S708.

[0084] In step S708, calculation unit 115 receives data (first electrical signal) relating to the temperature of hydrogen peroxide gas from temperature sensor 103, which measures the temperature of the hydrogen peroxide gas in measurement cell 101. As in steps S703, S704, S706, and S707, the received data (first electrical signal) relating to temperature is temporarily stored in a storage device within calculation unit 115 shown, and is then used when calculating the hydrogen peroxide gas concentration within calculation unit 115 in step S710, which will be described below. The process proceeds to step S709.

[0085] In step S709, calculation unit 115 receives data (second electrical signal) related to the pressure of hydrogen peroxide gas from pressure sensor 104, which measures the pressure of hydrogen peroxide gas inside measurement cell 101. As in steps S703, S704, and S706 to S708, the received data related to pressure (second electrical signal) is temporarily stored in a storage device within calculation unit 115 shown, and is then used when calculating the hydrogen peroxide gas concentration in calculation unit 115 in step S710 described below. The process proceeds to step S710.

[0086] In step S710, calculation unit 115 calculates the absorbance using the light amount (S11) stored in step S703, the light amount (S21) stored in step S704, the light amount (S12) stored in step S706, the light amount (S22) stored in step S707, and equation (2) described with reference to Fig. 1. Calculation unit 115 calculates the hydrogen peroxide gas concentration using the absorbance calculated using equation (2), the data related to the temperature stored in step S708, the data related to the pressure stored in step S709, and equation (1) described with reference to Fig. 1. The process proceeds to step S711.

[0087] In step S711, the data on the hydrogen peroxide gas concentration calculated in step S710 is output to an external device of concentration measuring device 100.

[0088] Although the processing of the concentration measuring device 100 is not shown for the purpose of simplicity of the drawing, the processing from step S706 to step S711 is performed continuously. When the power supply of the concentration measuring device 100 is turned off, the processing of the concentration measuring device 100 ends.

[0089] According to this aspect, the hydrogen peroxide gas concentration can be measured continuously and accurately.

[0090] Although the present specification has been described with reference to measuring the concentration of hydrogen peroxide gas, the present invention is also applicable to measuring the concentrations of other gases.

[0091] The embodiments described herein are for illustrative purposes and the present invention is not limited to the embodiments described. [Industrial Applicability]

[0092] The concentration measuring device of the present invention can be widely used in various industries where it is necessary to measure the concentration of a gas. [Explanation of symbols]

[0093] 100 Concentration measuring device 101 Measuring cell 102a Measurement gas flow path 102b Measurement gas flow path 103 Temperature Sensor 1031 Temperature Sensor 104 Pressure Sensor 1041 Pressure Sensor 1042 Pressure Sensor 105 Thermostatic Block 106 Temperature Sensor 107 Heater 108 Insulation 109 Light source lamp 110a Transparent window 110b Transparent window 111 Photodetector 112 Photodetector 113 Optical distributor 114 Control section 115 Arithmetic section 116 Cabinet 117a Air intake 117b Air intake 118 Exhaust port 120 Embedded Systems 121 Cooling area 122 Heat retention area 131 How light travels 132 How light travels 141a Flow of hydrogen peroxide gas 141b Flow of hydrogen peroxide gas 400 Conventional Measuring Cell 401 Conventional Cell Block 402 Conventional Cell Block 403 Conventional cell spacer 404a O-ring 404b O-ring 405a Fixed plate 405b Fixed plate 406a Fixing screw 406b Fixing screw 410a Conventional transmission window 410b Conventional transmission window 411 Optical path length 421 Measurement gas flow path 431 How light travels 501 Cell Block (First Cell Block) 502 Cell Block (Second Cell Block) 503 Cell Spacer 504a O-ring 504b O-ring 505a Fixed plate 505b Fixed plate 506a Fixing screw 506b Fixing screw 507a Gap Spacer 507b Gap Spacer 511 Optical path length 601 Part through which light passes

Claims

1. A concentration measurement device for measuring the concentration of hydrogen peroxide gas, comprising: a measurement cell through which the hydrogen peroxide gas flows and which is provided with a transmission window; a first sensor for measuring a temperature of the hydrogen peroxide gas to produce a first electrical signal; a second sensor that measures the pressure of the hydrogen peroxide gas to produce a second electrical signal; A thermostatic block containing the measurement cell, a third sensor for measuring the temperature of the thermostatic block to produce a third electrical signal; and A heater for heating the measurement cell and the transmission window A thermostatic block having A heat insulating material including the thermostatic block; a light source that emits light of a wavelength for measuring the concentration of the hydrogen peroxide gas; a first light receiving element that converts the amount of light emitted by the light source into a fourth electrical signal; a second light receiving element that converts the amount of light transmitted through the hydrogen peroxide gas flowing through the measurement cell into a fifth electrical signal; a distributor that splits the light emitted by the light source into light directed toward the first light receiving element and light directed toward the second light receiving element; An embedded system provided outside the insulation, a control unit that controls the heater based on the third electrical signal so as to maintain the temperature of the hydrogen peroxide gas in the measurement cell at a predetermined temperature; a calculation unit that calculates a concentration of the hydrogen peroxide gas based on the first electrical signal, the second electrical signal, the fourth electrical signal, and the fifth electrical signal; Embedded systems, including A concentration measuring device comprising:

2. 2. The concentration measuring device according to claim 1, further comprising a housing having an intake port and an exhaust port for ventilating the inside of the concentration measuring device.

3. 2. The concentration measuring device according to claim 1, wherein the temperature is 90° C. or higher and 200° C. or lower.

4. A concentration measurement device for measuring a concentration of a gas, comprising: a measurement cell through which the gas flows and which is provided with a transmission window; a first sensor for measuring a temperature of the gas to produce a first electrical signal; a second sensor that measures the pressure of the gas to produce a second electrical signal; a first light receiving element that converts an amount of light incident on the gas through the transmission window into a fourth electrical signal; a second light receiving element that converts an amount of light that has passed through the gas and is emitted from the transmission window into a fifth electrical signal; a heater for heating the measurement cell and the transmission window to maintain the gas at a predetermined temperature; an embedded system that calculates a concentration of the gas according to the Beer-Lambert law based on the first electrical signal, the second electrical signal, the fourth electrical signal, and the fifth electrical signal; A concentration measuring device comprising:

5. 5. The concentration measuring device according to claim 4, further comprising a heat insulating material for blocking the flow of heat between a heat retaining area including the measurement cell and the heater and a cooling area adjacent to the heat retaining area.

6. Further comprising a housing; The housing and the insulating material form the heat retention region and the cooling region, 6. The concentration measuring device according to claim 5, further comprising an intake port and an exhaust port for generating the cooling region inside the housing.

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