Station and method for measuring molecular contamination in air

Abstract

A solution is proposed for reducing or avoiding false positives and improving the reliability of contamination detection in measurement stations for molecular contamination in the air. A measuring station and a measuring method for airborne molecular contamination. The present invention relates to a measuring station (1) for airborne molecular contamination, said measuring station comprising: - at least one gas analyzer (3) configured to measure the concentration of at least one pollutant; - a plurality of air inlets (5) configured to be in fluid communication with the gas analyzer (3) and configured to be connected to a respective plurality of sampling lines (7); a plurality of first controllable shut-off valves (11) interposed between the plurality of air inlets (5) and the gas analyzer (3); a control unit (15) configured to control the opening and closing of the first controllable shut-off valve (11) to fluidly connect the gas analyzer (3) to at least one sampling line (7); The control unit (15) is configured to command verification of the accuracy of the gas analyzer (3) when the gas analyzer (3) detects a pollutant concentration greater than a predetermined threshold.

Description

[Technical Field]

[0001] The present invention relates to a measurement station for measuring airborne molecular contamination, particularly for monitoring molecular contamination in the atmosphere of a clean room, such as a clean room in a semiconductor manufacturing facility. The present invention also relates to a method for detecting airborne molecular contamination using such a measurement station. [Background technology]

[0002] In the semiconductor manufacturing industry, substrates such as semiconductor wafers or photomasks must be protected from airborne molecular contamination (AMC) to prevent it from damaging the chips or electronic circuits on the substrate. For this reason, wafers are placed in transport and storage boxes so that they can be transported from one piece of equipment to another or stored between two manufacturing steps. Furthermore, the transport boxes and equipment are placed in clean rooms where contamination levels are controlled and temperature, humidity, and pressure are maintained at precise and stable levels.

[0003] In cleanrooms, the gaseous components in the air can have a variety of origins and properties, including acids, bases, alcohols, condensable elements, doping elements, etc. These molecules can originate from the air in the semiconductor fabrication facility or from the outgassing of wafers after fabrication operations.

[0004] Gas analyzers installed in cleanrooms allow real-time assessment of the concentration of gaseous substances in the air, especially humidity, at very low levels, sometimes on the order of ppm or even below ppb.

[0005] These gas analyzers measure the ambient gas atmosphere, so a gas analyzer must be installed in each test zone of the clean room.

[0006] To reduce the risk of substrate contamination, the number of gas species measured and the number of test zones must be increased, but rapidly increasing the number of analyzers per zone and the number of zones tested makes this solution very costly.

[0007] To reduce costs, a measurement unit combining different analyzers has been proposed, which has multiple inlet ports, each corresponding to a specific test zone in the clean room via a sampling line.

[0008] However, due to the different lengths of the sampling lines and the potentially very low concentrations of contaminants, erroneous measurements can occur, especially false positives. Such false positives can lead to the shutdown of semiconductor production or operator intervention in the zone where the contamination was detected, which can be very costly. Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, there is a need to find solutions to reduce or avoid false positives and improve the reliability of contamination detection.

[0010] One of the objects of the present invention is to propose a measuring station and a measuring method which at least partially overcomes one of the above-mentioned drawbacks.

[0011] The subject of the present invention is therefore a measuring station for molecular contamination in the air, said measuring station comprising: - at least one gas analyzer configured to measure the concentration of at least one contaminant; - a plurality of air inlets configured to be in fluid communication with the gas analyzer and configured to be connected to one or more sampling lines; a plurality of first controllable shut-off valves interposed between the plurality of air inlets and the gas analyzer; a control unit configured to control the opening and closing of the first controllable shut-off valve to fluidly connect the gas analyzer to at least one sampling line; The control unit is configured to command a verification of the accuracy of the gas analyzer when a concentration of a contaminant greater than a predetermined threshold is detected by the gas analyzer.

[0012] When contaminant concentrations greater than a predetermined threshold are measured, verification of analyzer accuracy can limit cases of false contamination detection and simplify cleanroom contamination management.

[0013] According to another aspect of the invention, the measuring station also comprises a reservoir containing a reference fluid having a predetermined concentration of one or more pollutants to be monitored, and an additional valve arranged between the reservoir and the gas analyzer, and the control unit is configured to control the opening of the additional valve and to command the measurement of the concentration of one or more pollutants in the reservoir during verification of the accuracy of the gas analyzer.

[0014] Verification of accuracy can be performed by injecting a clean fluid or gas (containing no contaminants) or a reference fluid or gas (which may contain one or more compounds) with a controlled (known) concentration of one or more contaminants. The reference fluid or gas is supplied through a permeation tube, with or without heating. The measurement station can also include means for diluting the reference fluid or gas, configured to obtain a reference fluid or gas containing a different respective concentration of one or more contaminants than the reference gas in reservoir 17.

[0015] According to another aspect of the invention, the measuring station also comprises: - a first reservoir containing a fluid having a predetermined concentration of one or more contaminants to be monitored, and a first additional valve associated with a first mass flow meter for controlling the establishment of fluid communication between said first reservoir and said gas analyzer; a second reservoir containing a fluid that does not contain the contaminant to be monitored, and a second additional valve associated with a second mass flow meter for controlling the establishment of fluid communication between the second reservoir and the gas analyzer, wherein the control unit is configured, during verification of the accuracy of the gas analyzer, to control the opening of one of the first or second additional valves and instruct the gas analyzer to measure the concentration of the contaminant in one of the first or second reservoirs, to control the closing of one of the first or second additional valves and control the opening of the other of the first or second additional valves and instruct the gas analyzer to measure the concentration of the contaminant in the other of the first or second reservoirs, to compare the measured value with a predetermined contaminant concentration, and to verify whether the difference between the measured value and the predetermined contaminant concentration is less than a predetermined maximum difference.

[0016] According to another aspect of the invention, the control unit can be configured to command a measurement of the concentration in the first reservoir prior to a measurement of the concentration in the second reservoir. Other concentrations can be achieved in the two reservoirs by diluting the contaminant in the first reservoir with gas in the second reservoir. Mass flow meters associated with the first and second reservoirs can be used to achieve the desired dilution.

[0017] According to another aspect of the invention, the control unit is configured to generate and / or transmit a warning signal when a concentration of a contaminant greater than a predetermined threshold is detected by the gas analyzer, thereby verifying the accuracy of the gas analyzer, the warning signal being transmitted to a remote server, for example a client server.

[0018] According to another aspect of the present invention, the measurement station may include a plurality of gas analyzers arranged in parallel, and a plurality of second controllable shut-off valves interposed between the plurality of air inlets and each of the plurality of gas analyzers to control the establishment of fluid communication between the gas analyzers and the air inlet.

[0019] According to another aspect of the present invention, the control unit is configured to control the opening and closing of the first and second controllable shut-off valves so as to establish fluid communication between the sampling line and the gas analyzer sequentially and / or simultaneously according to a predetermined order.

[0020] According to another aspect of the invention, the control unit is configured to command verification of the accuracy of a particular gas analyzer only when a concentration of a contaminant greater than a predetermined threshold is detected by that gas analyzer.

[0021] According to another aspect of the invention, the control unit (15) is configured to generate and / or transmit a warning signal when a concentration of a contaminant greater than a predetermined threshold is detected and an accuracy verification is initiated, the warning signal being transmitted to a remote server, for example a client server.

[0022] According to another aspect of the invention, the air inlet comprises means for adjusting the air flow rate so that the transport rate through the different sampling lines to which the air inlet is connected is the same regardless of their length and / or their diameter.

[0023] According to another aspect of the invention, the means for adjusting the air flow rate is a valve with a micro-leak, i.e. a valve that allows for precise regulation of the flow rate.

[0024] According to another aspect of the present invention, if, during accuracy verification of the gas analyzer, the difference between the measured concentration value and a predetermined concentration is greater than a predetermined maximum difference, the control unit is configured to command a recalibration of the gas analyzer.

[0025] The present invention also relates to a method for detecting molecular contamination in air using a measurement station comprising a gas analyzer and a plurality of air inlets configured to be in fluid communication with the gas analyzer and configured to be connected to one or more sampling lines, the method comprising: - establishing sequential fluid communication between the sampling lines associated with the air inlets and the gas analyzers, and then measuring concentrations of one or more contaminants to be monitored in the sampling lines, wherein the sampling lines are sequentially placed in fluid communication with the gas analyzers to measure contaminant concentrations in different sampling lines; - verifying the accuracy of the gas analyzer if the contaminant concentration measurement exceeds a predefined threshold.

[0026] According to another aspect of the invention, once the accuracy of the gas analyzer is verified, an alert signal is generated from the measurement station or transmitted to a remote server.

[0027] According to another aspect of the invention, the measurement station includes a plurality of gas analyzers capable of measuring a contaminant or a set of contaminants, the gas analyzers being positioned in simultaneous fluid communication with the sampling line.

[0028] According to another aspect of the invention, the step of verifying the accuracy of the gas analyzer includes establishing fluid communication between the gas analyzer and a first reservoir containing a fluid having a predetermined concentration of a contaminant to be monitored and measuring the concentration using the gas analyzer, and then establishing fluid communication between the gas analyzer and a second reservoir containing a fluid without the contaminant to be monitored and measuring the concentration using the gas analyzer.

[0029] Other characteristics and advantages of the invention will appear more clearly on reading the following description, given by way of illustrative and non-limiting example, and the accompanying drawings, in which: [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 2 is a diagram of a measurement station and associated sampling lines according to a first embodiment. [Figure 2] FIG. 10 is a diagram of a measurement station and associated sampling lines according to a second embodiment. [Figure 3] FIG. 10 is a diagram of a measurement station and associated sampling lines according to a third embodiment. [Figure 4a] FIG. 2 is a diagram of a reservoir associated with the spectrometer according to the first embodiment. [Figure 4b] FIG. 10 is a diagram of a reservoir associated with a spectrometer according to a second embodiment. [Figure 5] FIG. 1 is a flow diagram illustrating steps in a method for detecting molecular contamination in air using a measurement station. DETAILED DESCRIPTION OF THE INVENTION

[0031] In these figures, identical components are labeled with the same reference numerals.

[0032] The following embodiments are illustrative. Although the specification refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment or that a feature applies to a single embodiment. Individual features of different embodiments may be combined or interchanged to provide other embodiments.

[0033] The present invention relates to a measuring station for measuring molecular contamination in air. FIG. 1 is a diagram of such a measuring station 1. The measuring station 1 comprises a plurality of gas analyzers 3 (three in this embodiment). Each analyzer 3 can be configured to measure the concentration of a predetermined contaminant or a set of predetermined contaminants. The measuring station 1 also comprises a plurality of air inlets 5, four in this case, configured to be in fluid communication with the gas analyzers 3. The fluid communication between the air inlets 5 and the gas analyzers 3 is achieved, for example, by ducts. The air inlets 5 are configured to be connected to one or more sampling lines 7, in particular one sampling line 7 per air inlet 5 in the embodiment of FIG. 1 (although one air inlet 5 may also be connected to multiple sampling lines 7). The ends of the sampling lines opposite the air inlets 5 constitute sampling points 9. The sampling points 9 are distributed, for example, in different zones of a clean room.

[0034] In order to limit the influence of the length of the sampling lines 7 on the measurements by the analyzer 3, the air inlets 5 can be equipped with means for adjusting the air flow rate. These means for adjusting the air flow rate are configured so that the transport volume through the different sampling lines 7 is the same regardless of their length. These means for adjusting the air flow rate are, for example, valves with micro-leakage, which make it possible to ensure the same flow rate for all sampling lines regardless of their length and / or diameter.

[0035] The measurement station 1 also includes a plurality of first controllable shutoff valves 11 interposed between the plurality of air inlets 5 and the gas analyzers 3, respectively, to allow or prevent fluid communication between the air inlets 5 and the gas analyzers 3. The first controllable shutoff valves 11 can be realized by a multiplexing valve that allows or prevents fluid communication between one or more air inlets 5 and one or more gas analyzers 3. The measurement station 1 also includes a conditioning pump 13 configured to draw air from the sampling line 7 to the gas analyzers 3. The conditioning pump 13 is connected to the air inlets 5, for example, via a duct. Alternatively, the conditioning pump 13 can be located downstream of the first controllable shutoff valve 11, as shown in FIG. 2. In this embodiment, at least one controllable shutoff valve 11 may need to be open to ensure proper operation of the conditioning pump 13. As a further alternative, to select the analyzers 3 connected to the air inlets 5, a plurality of second controllable shutoff valves 11' can be located at the inlets of the analyzers 3, as shown in FIG. 3. These second controllable shut-off valves 11' can also be used when the conditioning pump 13 is arranged as in the embodiment of Figure 1. The analyzer 3 may also be equipped with its own suction means, such as an internal sampling pump, in which case the use of the conditioning pump 13 is not necessary.

[0036] The measurement station 1 also includes a control unit 15. The control unit 15 may comprise, for example, a microcontroller or microprocessor. The control unit 15 is configured to control the opening and closing of the first shut-off valve 11 and / or the second shut-off valve 11' to establish or not establish fluid communication between the gas analyzer 3 and the sampling line 7, allowing air from different sampling points 9 to be analyzed. The sampling lines 7 may be arranged to be in fluid communication with one another in a predetermined order. A particular sampling line 7 may also be arranged to be in fluid communication with the gas analyzer 3 simultaneously, in order to simultaneously analyze air from multiple sampling points 9.

[0037] The control unit 15 is also connected to the conditioning pump 13 and the analyzer 3. The control unit 15 is also configured to command a verification of the accuracy of the gas analyzer 3 when a concentration of a pollutant higher than a predetermined threshold is detected by the gas analyzer 3 to avoid false detection of the pollutant.

[0038] For this purpose, as shown in FIG. 4a, the measuring station 1 includes a first reservoir 17 associated with the analyzer 3, a first additional valve 21 and a first flow meter 24 located between the first reservoir 17 and the analyzer 3 (the first additional valve 21 and the first flow meter 24 can be combined into a single device corresponding to a mass flow controller), a second reservoir 19 associated with the analyzer 3, and a second additional valve 23 and a second flow meter 26 located between the second reservoir 19 and the analyzer 3 (the second additional valve 23 and the second flow meter 26 can be combined into a single device corresponding to a mass flow controller). The first reservoir 17 and the second reservoir 19 are, for example, cylinders of pressurized gas. According to an alternative embodiment shown in FIG. 4b, the reservoirs 17 and 19 are not fluidly connected to a pipe equipped with a shut-off valve 11 to avoid contamination of the sampling line by contaminants contained in the first reservoir 17.

[0039] The first reservoir 17 contains a fluid having a first predetermined concentration of one or more contaminants to be monitored, e.g., benzene, which may be between 1 and 100 ppb. The second reservoir 19 contains a fluid having a second predetermined concentration of the contaminants to be monitored; in particular, this second predetermined concentration may be zero, so that the fluid in the second reservoir 19 contains no contaminants, e.g., clean air. The contents of the second reservoir 19 can then be used to dilute the contaminants contained in the first reservoir 17, resulting in more than two different predetermined concentrations using only two reservoirs. It is also possible to use multiple reservoirs containing different predetermined concentrations of contaminants.

[0040] In practice, a first reservoir 17 and a second reservoir 19 are associated with each analyzer 3. More than two reservoirs 17, 19 can be associated with one analyzer 3, with different reservoirs 17, 19 having different predetermined concentrations.

[0041] Alternatively, the measuring station 1 may comprise a single reservoir 17 containing a reference fluid having predetermined concentrations of one or more pollutants to be monitored and an additional valve 21 arranged between the reservoir 17 and the gas analyzer 3, the control unit 15 being configured to control the opening of the additional valve 21 and to command the measurement of the concentrations of the one or more pollutants in the reservoir 17 during verification of the accuracy of the analyzer 3. The measuring station 1 may also comprise means for diluting the reference fluid or gas, configured to obtain a reference fluid or gas containing respective concentrations of the one or more pollutants different from those of the reference gas in the reservoir 17.

[0042] Verification of accuracy can be accomplished by injection of a clean fluid or gas (containing no contaminants) or a reference fluid or gas (which may contain one or more compounds) with a controlled (known) concentration of one or more contaminants. The reference fluid or gas can also be delivered through a permeation tube, with or without heating.

[0043] Thus, when a concentration above a predetermined threshold is detected by the analyzer 3, the control unit 15 commands a verification of the accuracy of the analyzer 3. In practice, this automatic verification can be performed for a specific analyzer 3. Furthermore, before starting the verification of the accuracy of the analyzer 3, the concentration measurement can be repeated to verify that the predetermined threshold has been exceeded.

[0044] This verification involves, as a first step, measuring the concentration of the fluid contained in the first reservoir 17 by the analyzer 3 by opening the first additional valve 21 and closing the other valves 11 and 23 located on the duct connected to the analyzer 3, and, as a second step, measuring the concentration of the fluid contained in the second reservoir 19 by opening the second additional valve 23 and closing the other valves 11 and 21 located on the duct connected to the analyzer 3. The control unit 15 is also configured to compare the value measured by the analyzer 3 with a predetermined concentration. If the difference between the measured value and the predetermined concentration is smaller than a predefined maximum difference, the analyzer 3 is considered reliable, i.e., its accuracy is verified and the detection of the contaminant is confirmed. The predefined maximum difference can be selected by the user and entered via an interface linked to the control unit 15, for example, a touchscreen or an operating button. The second reservoir can also be used to dilute the concentration of the first reservoir (for example, the second reservoir is used to dilute the first reservoir when the second reservoir is clean air). The two additional valves 21 and 23 can be opened simultaneously to provide different concentrations. Different predetermined concentrations can then be sent sequentially to the analyzer 3 to verify its accuracy.

[0045] The control unit 15 is then configured to issue an alert signal, such as a visual and / or audible signal, or to transmit an alert signal, for example to a remote server.

[0046] Additionally, a first warning signal may be issued prior to verification of the analyzer 3 to indicate that a concentration of a contaminant greater than a predetermined threshold has been detected by the analyzer 3 and verification of the analyzer 3 is initiated.

[0047] In contrast, if, during accuracy verification of the analyzer 3, the measured value differs from the predetermined concentration by more than a predefined maximum difference, the analyzer 3 is deemed unreliable and the detection of contaminants is not confirmed. The control unit 15 is then configured to initiate a recalibration of the analyzer 3. Alternatively, the control unit 15 can issue a warning signal to indicate the verification result and allow the operator to decide what action to take. Furthermore, as a second step, a contaminant-free fluid in the second reservoir 19 can be measured to ensure that it does not distort subsequent measurements made by the analyzer 3. In fact, the use of contaminant-free gas makes it possible to purge the analyzer 3 and even the ducts adjacent to the analyzer 3.

[0048] The invention also relates to a method for detecting molecular contamination in air using a measuring station 1 such as described above.

[0049] A flow diagram of the steps of this method is shown in Figure 5. The order of the steps or sub-steps may differ from the order presented, and certain steps or sub-steps may occur simultaneously.

[0050] The first step 101 concerns the establishment of fluid communication between one or more sampling lines 7 associated with different air inlets 5 and one or more analyzers 3. The fluid communication is established by the control unit 15 by controlling the opening and closing of different valves 11, 11' of the measuring station 1.

[0051] The second step 102 involves measuring, by an analyzer or analyzers 3, the concentration of one or more contaminants to be monitored in a sampling line or sampling lines 7 in fluid communication with the analyzer or analyzers 3. When multiple analyzers 3 are used, each analyzer 3 may be configured to measure the concentration of a different contaminant or set of contaminants than the other analyzers 3.

[0052] A third step 103 concerns the comparison of the concentration values ​​of the pollutants measured by the analyzer 3 with predefined thresholds set by the user. Different thresholds can be defined, associated with different actions or different warnings, to allow a better assessment of the magnitude of the contamination.

[0053] Steps 101 to 103 are repeated in a predefined order to sequentially place different air inlets 5 (and therefore different sampling lines 7) in fluid communication with one or more analyzers 3, allowing multiple air inlets 5 to be simultaneously in fluid communication with one or more analyzers 3. The concentration of the contaminant is measured and compared with a predefined threshold for each configuration of valves 11, 11' before moving on to the next configuration of valves 11, 11'.

[0054] If the measured concentration of the contaminant exceeds a predefined threshold, the control unit 15 initiates a procedure to verify the accuracy of the analyzer 3 , corresponding to step 104 .

[0055] This step 104 comprises a first sub-step 1041 relating to the closing of the valves 11, 11' of the ducts connected to the analyzer 3 whose accuracy is to be verified and to the opening of a first additional valve 21 associated with this analyzer 3. A second sub-step 1042 relates to the measurement of the concentration of the contaminant in the first reservoir 17 by the analyzer 3. A third sub-step 1043 relates to the closing of the first additional valve 21 and the opening of the second additional valve 23. A fourth sub-step 1044 relates to the measurement of the concentration of the contaminant in the second reservoir 19 by the analyzer 3 or in a mixture between the first reservoir 17 and the second reservoir 19 at a predefined dilution ratio. A fifth substep 1045 concerns the comparison of the value measured by the analyzer 3 with the expected contaminant concentration in the first reservoir 17 and the second reservoir 19, or in a mixture of gases from the two reservoirs 17 and 19 (a predefined dilution of the concentration in the first reservoir 17 with the second reservoir 19), and comparing these differences with a predetermined maximum tolerance. If the difference is lower than the maximum tolerance, the measurement by the analyzer 3 is considered reliable, the contaminant concentration value measured in step 102 and greater than a predetermined threshold is confirmed, and the method proceeds to step 105, where an alarm can be issued indicating this contaminant concentration.

[0056] To confirm the initial measurement, one or more new measurements can be made of the sampling lines 7 where concentrations above a predetermined threshold were measured. These new measurements can also be made in zones adjacent to the zone where contamination was detected. If contamination is detected simultaneously in several analyzed sampling lines 7, a new measurement can be made in one of these sampling lines 7 to improve the determination of the extent of the contamination zone area.

[0057] Alternatively, it is possible to start by measuring the concentration of the contaminant in the second reservoir 19 (or a mixture of the two reservoirs 17, 19) and then measure the concentration in the first reservoir 17. Multiple reservoirs 17 containing different contaminants or different concentrations of contaminants can also be used.

[0058] If the difference between the measured value and the predefined concentration is greater than the maximum allowable difference, the measurement by the analyzer 3 is considered unreliable and the method proceeds to step 106, where recalibration of the analyzer 3 is required and a warning may be issued indicating that the analyzer 3 is unreliable.

[0059] By verifying the accuracy of the analyzer 3 when the analyzer 3 measures a contaminant concentration greater than a predetermined threshold, it is not necessary to verify the accuracy every time the analyzer 3 measures, and it is possible to reduce the number of false positives. Specifically, a measurement takes several minutes, for example, 5 minutes, but accuracy verification may take several tens of minutes, for example, 20 minutes. When contamination is detected, an operator usually intervenes to analyze the cause of the contamination and improve the contamination, so cleanroom contamination control is not as constrained (due to the reduction in the number of false positives). [Explanation of symbols]

[0060] 1 Measuring Station 3 Gas analyzers, analyzers 5 Air inlet 7 Sampling Line 9 Sampling Points 11 First controllable shutoff valve 11' Second controllable shut-off valve 13 Conditioning Pump 15 Control Unit 17 First Reservoir 19 Second reservoir 21 First additional valve 23 Second additional valve 24 1st flow meter 26 2nd flow meter

Claims

1. A measuring station (1) for measuring molecular contamination in air, said measuring station (1) comprising: at least one gas analyzer (3) configured to measure the concentration of at least one pollutant; a plurality of air inlets (5) configured to be in fluid communication with said gas analyzer (3) and configured to be connected to one or more sampling lines (7); a plurality of first controllable shut-off valves (11) interposed between said plurality of air inlets (5) and said gas analyzer (3); a control unit (15) configured to control the opening and closing of said first controllable shut-off valve (11) to place said gas analyzer (3) in fluid communication with at least one sampling line (7); The measuring station (1) is characterized in that the control unit (15) is configured to command a verification of the accuracy of the gas analyzer (3) when the gas analyzer (3) detects a concentration of a pollutant greater than a predetermined threshold.

2. 2. The measuring station (1) according to claim 1, further comprising a reservoir (17) containing a reference fluid having a predetermined concentration of one or more pollutants to be monitored, and an additional valve (21) arranged between the reservoir (17) and the gas analyzer (3), wherein the control unit (15) is configured to control the opening of the additional valve (21) and to command the measurement of the concentration of one or more pollutants in the reservoir (17) during verification of the accuracy of the gas analyzer (3).

3. The system also includes a first reservoir (17) containing a fluid having a predetermined concentration of one or more contaminants to be monitored, a first additional valve (21) associated with a first mass flow meter (24) for controlling the establishment of fluid communication between the first reservoir (17) and the gas analyzer (3), a second reservoir (19) containing a fluid not containing the contaminants to be monitored, and a second additional valve (23) associated with a second mass flow meter (26) for controlling the establishment of fluid communication between the second reservoir (19) and the gas analyzer (3), and the control unit (15) controls the operation of one of the first or second additional valves (21, 23) during verification of the accuracy of the gas analyzer (3).

3. The measuring station (1) according to claim 1 or 2, characterized in that it is configured to control the opening of one of the first or second additional valves (21, 23), command the gas analyzer (3) to measure the concentration of the pollutant in one of the first or second reservoirs (17, 19), control the closing of one of the first or second additional valves (21, 23), control the opening of the other of the first or second additional valves (21, 23), command the gas analyzer (3) to measure the concentration of the pollutant in the other of the first or second reservoirs (17, 19), compare the measured value with a predetermined pollutant concentration, and verify whether the difference between the measured value and the predetermined pollutant concentration is less than a predetermined maximum difference.

4. 4. The measuring station (1) according to claim 3, characterized in that the control unit (15) is configured to command the measurement of the concentration in the first reservoir (17) prior to the measurement of the concentration in the second reservoir (19).

5. 3. The measuring station (1) according to claim 1 or 2, characterized in that the control unit (15) is configured to issue a warning signal if a concentration of a pollutant greater than a predetermined threshold is detected by the gas analyzer (3), thereby verifying the accuracy of the gas analyzer (3).

6. 3. The measuring station (1) according to claim 1 or 2, characterized in that it comprises a plurality of gas analyzers (3) arranged in parallel, and a plurality of second controllable shut-off valves (11') interposed between the plurality of air inlets (5) and each of the plurality of gas analyzers (3) so as to control the establishment of fluid communication between the gas analyzers (3) and the air inlets (5).

7. 7. The measuring station (1) according to claim 6, wherein the control unit (15) is configured to control the opening and closing of the first and second controllable shut-off valves (11, 11') so as to establish fluid communication between the sampling line (7) and the gas analyzer (3) sequentially and / or simultaneously according to a predetermined order.

8. 7. The measuring station (1) of claim 6, wherein the control unit (15) is configured to command verification of the accuracy of a particular gas analyzer (3) only for that particular gas analyzer (3) if a pollutant concentration greater than a predetermined threshold is detected by that gas analyzer (3).

9. 3. The measuring station (1) according to claim 1 or 2, characterized in that the control unit (15) is configured to issue a warning signal when a concentration of a pollutant greater than a predetermined threshold is detected and a verification of accuracy is initiated.

10. 3. The measuring station (1) according to claim 1 or 2, characterized in that the air inlet (5) comprises means for adjusting the air flow rate so that the conveyance through the different sampling lines (7) to which the air inlet (5) is connected is the same regardless of their length and / or their diameter.

11. 11. Measuring station (1) according to claim 10, characterized in that the means for regulating the air flow rate are valves with micro-leakage.

12. 3. The measuring station (1) according to claim 1 or 2, characterized in that the control unit (15) is configured to command a recalibration of the gas analyzer (3) if the difference between the measured concentration value and the predetermined concentration is greater than a predetermined maximum difference.

13. 1. A method for detecting molecular contamination in air using a measurement station (1) comprising a gas analyzer (3) and a plurality of air inlets (5) configured to be in fluid communication with the gas analyzer (3) and to be connected to one or more sampling lines (7), the method comprising: - establishing a sequential fluid communication between the sampling line (7) associated with the air inlet (5) and the gas analyzer (3) and measuring the concentration of one or more pollutants to be monitored in the sampling line (7); - verifying the accuracy of said gas analyzer (3) if the measured concentration of said pollutant exceeds a predefined threshold.

14. 14. The method for detecting molecular contamination in air according to claim 13, characterized in that, once the accuracy of the gas analyzer (3) is verified, an alarm signal is generated and / or transmitted to a remote server.

15. 15. The method for detecting molecular contamination in air according to claim 13 or 14, characterized in that the measuring station (1) comprises a plurality of gas analyzers (3) associated with a contaminant or a set of contaminants, the gas analyzers (3) being arranged in simultaneous fluid communication with the sampling line (7).

16. 15. The method for detecting molecular contamination in air according to claim 13 or 14, characterized in that the step of verifying the accuracy of the gas analyzer (3) comprises establishing fluid communication between the gas analyzer (3) and a first reservoir (17) containing a fluid having a predetermined concentration of the contaminant to be monitored and measuring the concentration using the gas analyzer (3), and then establishing fluid communication between the gas analyzer (3) and a second reservoir (19) containing a fluid not containing the contaminant to be monitored and measuring the concentration using the gas analyzer (3).

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