Station and method for measuring airborne molecular contaminants

Abstract

The invention relates to a station (1, 1') for measuring molecular pollutants borne by air, comprising at least one gas analyzer (2) and a regulating pump (3), characterized in that it also comprises a sequencing unit (4), the sequencing unit comprising a sequencing program, the sequencing program defining the order of measurements to be performed for at least two sampling lines (L1-L16), the sequencing unit (4) being configured to control the connection of the sampling line (L1-L16) to be measured, whose measurement is programmed to follow the measurement of the sampling line (L1-L16) being measured, to the regulating pump (3), and at the same time to control the connection of the sampling line (L1-L16) being measured to the at least one gas analyzer (2). The invention also relates to a method for measuring molecular pollutants borne by air by means of such a station.

Description

Technical Field

[0001] The present invention relates to a station for measuring molecular contaminants borne by air, in particular for monitoring the concentration of molecular contaminants in the atmosphere of a clean room, such as a clean room in a semiconductor manufacturing plant. The present invention also relates to a method for measuring molecular contaminants borne by air by means of such a station. Background Art

[0002] In the semiconductor manufacturing industry, substrates such as semiconductor wafers or photomasks must be protected from airborne molecular contaminants (AMCs) in order to prevent such contaminants from damaging the electronic circuitry of the chip or substrate. To this end, the substrates are contained in atmospheric transport and storage boxes, which allow the substrates to be transported from one piece of equipment to another, or to be stored between two manufacturing steps. Furthermore, the transport boxes and equipment are arranged in clean rooms, where the level of particles is minimized and the temperature, humidity and pressure are maintained at precise levels.

[0003] In a cleanroom, airborne gaseous species may have different origins and be of different types, such as encountering acids, bases, condensable elements, doping elements, etc. These molecules may originate from the air in a semiconductor manufacturing plant or may be specifically released by semiconductor wafers that have undergone previous manufacturing operations.

[0004] Gas analyzers in cleanrooms allow real-time assessment of the concentration of airborne gaseous substances, in particular humidity and certain acids. The measured concentrations are sometimes very low, for example in the order of ppm or ppb. Since these gas analyzers measure the gas atmosphere around them, they need to be set up in each test area of ​​the cleanroom.

[0005] To reduce the risk of contaminating the substrate, it is necessary to increase the number of gaseous substances measured and increase the number of test areas. However, increasing the number of analyzers per area and increasing these test areas means that this solution quickly becomes very expensive.

[0006] In order to reduce costs, measurement units have been proposed that combine different analyzers. This unit has a number of input ports, each directed to a specific test area of ​​the cleanroom. Since cleanrooms can be very large and the number of test areas is also increasing, a large number of sampling lines are used, the length of which usually extends for the most part to several tens of meters. This long path taken by the gas to reach the measurement unit of the analyzer is very time-consuming, which means that the information is delayed. In fact, the entire volume contained in the sampling line needs to be "replaced" at least once with the gas to be measured, and this gas can also easily adhere to the walls of the line by adsorption, especially for the gaseous substances to be measured, which are called polar substances. Therefore, for each change of the test area, it is difficult to obtain a measurement value that actually represents the concentration of the gaseous substance in the test area without waiting for a long time.

[0007] One solution involves simultaneous suction in all sampling lines. All sampling lines are thus conditioned by common degassing, while the measurement of the gas concentration is carried out in one line. Gas is thus constantly suctioned in all sampling lines, which in particular allows good degassing of the sampling lines.

[0008] However, due to the large number of lines to be sampled simultaneously, this solution results in a significant reduction in the pumping rate in each line. The response time in the sampling line in which the measurement is made is prolonged compared to a solution in which the entire pumping rate is dedicated to sampling one line to be measured. In addition, the sampling lines are not all of equal length. Some lines may be short, while others may be long. Therefore, the pumping rate may show large differences between the lines. It may even happen that the difference in length between two lines is so great that a suitable pumping rate in one line is equivalent to a practically zero pumping rate in the other line.

[0009] One solution might involve increasing the pumping capacity for simultaneous sampling. However, this would incur relatively high costs. Summary of the invention

[0010] An object of the present invention is to propose a measuring station that at least partially solves the above-mentioned drawbacks.

[0011] To this end, the object of the present invention is a station for measuring molecular pollutants transmitted by the air, which includes at least one gas analyzer and a regulating pump, characterized in that it also includes a sequencing unit, which includes a sequencing program, which defines the order of measurements to be performed for at least two sampling lines, and the sequencing unit is configured to control the connection of the sampling line to be measured, for example a single sampling line - the measurement of which is programmed to follow (after) the measurement of the sampling line being measured - to the regulating pump, and at the same time control the connection of the sampling line being measured to the at least one gas analyzer.

[0012] The sampling line can thus be conditioned under optimal and fast pumping conditions.

[0013] In fact, the measurement time is reduced because the adjustment of the sampling line is performed during the hidden time.

[0014] Furthermore, the regulation can be performed using maximum pumping, independent of the number of sampling lines. Thus, the number of sampling lines can be increased without changing the pumping performance for regulation. Thus, the gas sucked out before the measuring line allows the sampling line to be degassed. Thus, the measurement can be more precise, in particular when significant changes in concentration occur between two areas to be tested successively and when sufficient degassing time is required to obtain a measurement that is actually representative of the concentration in the test area.

[0015] Thus, the concentrations of different airborne gaseous substances at different locations of the clean room can be measured using the same set of gas analyzers, wherein a measuring station is directed to an input port in each test area of ​​the clean room, thereby limiting costs.

[0016] According to a first embodiment, the measuring station comprises:

[0017] - A sampling electric valve on each sampling pipeline, which can be controlled by a sequencing unit;

[0018] - first and second regulating electric valves controllable by a sequencing unit, which are arranged as branches of the input of the regulating pump;

[0019] - A first and a second measuring electric valve which can be controlled by a sequencing unit, which are arranged as branches of the input end of the at least one gas analyzer, the first regulating electric valve and the first measuring electric valve being connected to the sampling electric valves of the sampling pipeline of the first series, and the second regulating electric valve and the second measuring electric valve being connected to the sampling electric valves of the sampling pipeline of the second series.

[0020] Such a measuring station comprises, for example, at least five sampling motor valves.

[0021] The first series of sampling lines may include the same number of sampling lines as the second series.

[0022] The sequencing program defines, for example, a sequence of measurements to be performed which causes the measurements to be performed to be performed alternately in the series of sampling lines. This solution allows limiting the number of valves used, thus allowing simplifying the equipment and controlling costs.

[0023] According to a second embodiment, the measuring station comprises:

[0024] a first regulating electric valve, which can be controlled by the sequencing unit and is arranged at the input of the regulating pump;

[0025] a first measuring electric valve, which can be controlled by a sequencing unit and is arranged at the input of the at least one gas analyzer, the first measuring electric valve and the first regulating electric valve being connected to the sampling line;

[0026] at least one second regulating electric valve, which can be controlled by the sequencing unit and is arranged as a branch from the first regulating electric valve and the input of the regulating pump;

[0027] - at least one second measuring electric valve controllable by a sequencing unit, said at least one second measuring electric valve being arranged as a branch of the first measuring electric valve and the input of said at least one gas analyzer, said at least one second measuring electric valve and said at least one second regulating electric valve being connected to at least one corresponding sampling line.

[0028] The measuring station comprises, for example, less than four second regulating electric valves and less than four second measuring electric valves.

[0029] Another object of the invention is a method for measuring airborne molecular pollutants with the aid of a measuring station as described above, characterized in that a sampling line, for example a single sampling line, is regulated, the measurement of which is programmed to follow the measurement of a sampling line being measured, while measurements are carried out in the sampling line using at least one gas analyzer.

[0030] According to one embodiment of the method for measuring by means of the measuring station according to the first embodiment, the measurements to be performed are performed alternately in each of two series of sampling lines, a first series of sampling lines being connected to a first regulating electric valve and a first measuring electric valve, and a second series of sampling lines being connected to a second regulating electric valve and a second measuring electric valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Other characteristics and advantages of the invention will become apparent from the following description provided by way of non-limiting example with reference to the accompanying drawings, in which:

[0032] Figure 1A schematic diagram showing a first embodiment of a station for measuring airborne molecular contaminants;

[0033] Figure 2 Shown is the use of Figure 1 Schematic diagram of a method for measuring molecular pollutants borne by air using a measuring station;

[0034] Figure 3 A schematic diagram showing a second embodiment of a station for measuring airborne molecular contaminants;

[0035] Figure 4 Shown is the use of Figure 3 Schematic diagram of the method for measuring airborne molecular pollutants using a measuring station.

[0036] In all of the drawings, the same elements are provided with the same reference numerals. DETAILED DESCRIPTION

[0037] The following embodiments are all examples. Even if the description refers to one or more embodiments, this does not necessarily mean that each reference refers to the same embodiment, or that these features apply to only one embodiment. Simple features of various embodiments may also be combined to provide other embodiments.

[0038] Figure 1 Elements of a station 1 for measuring airborne molecular contaminants are shown, the station 1 being particularly useful for monitoring the concentration of molecular contaminants in the atmosphere of a clean room, such as a clean room in a semiconductor manufacturing plant.

[0039] The measuring station 1 comprises at least one gas analyzer 2 , a regulating pump 3 and a sequencing unit 4 .

[0040] According to one embodiment, the gas analyzer 2 comprises a small sampling pump. The gas analyzer 2 allows real-time measurement of the concentration of at least one gaseous substance, i.e., a measurement time of less than a few seconds, and even less than a few minutes for low concentrations below ppm or ppb. The measured gaseous substance is, for example, an acid, such as hydrofluoric acid HF or hydrochloric acid HCl, or a solvent, such as PGMEA (propylene glycol methyl ether). According to another embodiment, the gaseous substance is ammonia NH3. The gas analyzer 2 can be adapted to measure different gaseous substances or a group of different gaseous substances.

[0041] The regulating pump 3 includes, for example, a small-capacity vacuum pump, such as a small multi-stage vacuum pump.

[0042] The sequencing unit 4 is, for example, a computer.

[0043] The sequencing unit 4 comprises a sequencing program which defines, for at least two of the sampling lines L1 - L16 , the order in which measurements are to be performed.

[0044] The sampling lines L1-L16 comprise, for example, flexible tubes made of a material that limits the adhesion of gaseous substances to the walls, such as perfluoroalkoxy (also known as PFA) or polytetrafluoroethylene (also known as PTFE). The sampling lines L1-L16 connect the measuring station 1 to a specific test area of ​​the clean room. The length of the sampling lines L1-L16 can vary between the various test areas to be reached and can be several tens of meters in length, for example between 40 and 200 meters in length.

[0045] The sequencing program defines the order in which the measurements are to be performed, ie the order in which the concentration measurements of the gaseous substances have to be carried out in the sampling lines L1 - L16 connected to the measuring station 1 .

[0046] The sequencing unit 4 is also configured to control the connection of the sampling lines L1 - L16 to be measured, for example a single sampling line, to the regulating pump 3 , while it controls the connection of the sampling lines L1 - L16 being measured to the at least one gas analyzer 2 .

[0047] Therefore, a distinction should be made between sampling lines “being measured” and sampling lines “to be measured.” The sampling lines “to be measured” among the sampling lines L1 - L16 are lines programmed to be measured after the sampling lines L1 - L16 being measured.

[0048] To this end, according to Figure 1 In the first embodiment shown, the measuring station 1 comprises:

[0049] - a sampling electric valve 5 on each sampling line L1 - L16 , which can be controlled by a sequencing unit 4 ;

[0050] - a first and a second regulating electric valve 6a, 6b controllable by the sequencing unit 4, arranged as a branch of the input 7 of the regulating pump 3; and

[0051] A first and a second measuring electric valve 8 a , 8 b which can be controlled by the sequencing unit 4 and are arranged as branches of the input 9 of the at least one gas analyzer 2 .

[0052] A plurality of gas analyzers 2 for measuring the concentration of different gases or different groups of gaseous substances can be connected to the input 9, thereby sampling simultaneously from the same sampling line.

[0053] The first regulating electric valve 6a and the first measuring electric valve 8a are connected to the sampling electric valves 5 of the sampling lines L1, L3, L5, L7, L9, L11, L13, L15 of the first series S1. The first series S1 of sampling lines comprises at least one sampling line.

[0054] The second regulating electric valve 6b and the second measuring electric valve 8b are connected to the sampling electric valves 5 of the sampling lines L2, L4, L6, L8, L10, L12, L14, L16 of the second series S2. The sampling lines of the second series S2 include at least one sampling line.

[0055] For example, there are at least five sampling lines L1-L16, for example sixteen sampling lines L1-L16, each having a sampling electric valve 5. The first series S1 of sampling lines for example comprises the same number of sampling lines as the second series S2 (eight in this example).

[0056] The sequencer defines, for example, the order of the measurements to be performed, which causes the measurements to be performed to be performed alternately in the sampling lines of each series S1 , S2. This solution allows limiting the number of valves used, thus simplifying the equipment and controlling costs.

[0057] During operation, the sampling lines L1-L16 are regulated, for example, a single sampling line, the measurement of which is programmed to follow the measurement of the sampling line L1-L16 being measured, while measurements are made in the sampling lines L1-L16 using at least one gas analyzer 2. For example, measurements are made alternately in each of the sampling lines of the two series S1, S2.

[0058] For example, by defining a sequencing procedure of measurements of the concentration of the gaseous substance that must be performed in the sampling line L5 of the first series S1 and subsequently in the sampling line L4 of the second series S2, the sampling line L4 of the second series S2 is adjusted while measurements are performed in the sampling line L5 using the at least one gas analyzer 2.

[0059] To this end, the sequencing unit 4 controls the connection of the sampling line L4 to the regulating pump 3 by opening the sampling electric valve 5 and the second regulating electric valve 6 b of the sampling line L4 and closing the first regulating electric valve 6 a of the sampling electric valve 5 connected to the first series S1 .

[0060] At the same time, the sequencing unit 4 controls the connection between the sampling line L5 and the at least one gas analyzer 2 by opening the sampling electric valve 5 and the first measuring electric valve 8a of the sampling line L5 and closing the second measuring electric valve 8b of the sampling electric valve 5 connected to the second series S2 ( Figure 2 Step 101).

[0061] Then, after taking a measurement in the sampling line L5, the sequencing unit 4 controls the connection of the sampling line L4 with the at least one gas analyzer 2 by opening the sampling electric valve 5 and the second measuring electric valve 8b of the sampling line L4, and closing the first measuring electric valve 8a of the sampling electric valve 5 connected to the first series S1.

[0062] At the same time, the sequencing unit 4 controls the connection of the sampling pipeline of the first series S1 to the regulating pump 3, for which the concentration of the gaseous substance must be continuously measured ( Figure 2 Step 102).

[0063] Thus, the operations can be continued until all the measurements defined in the sequencer are performed in order. These operations can be repeated as a loop.

[0064] Thus, the concentrations of different airborne gaseous substances in different locations of the clean room can be measured using the same set of gas analyzers 2, wherein a measuring station 1 is directed to an input port in each test area of ​​the clean room, thereby limiting costs.

[0065] The sampling line can thus be conditioned under optimal and fast pumping conditions.

[0066] In fact, the measuring time is reduced since the conditioning of the sampling lines is performed simultaneously.

[0067] Furthermore, the regulation can be performed using maximum pumping, independent of the number of sampling lines. Thus, the number of sampling lines can be increased without changing the pumping performance for regulation. Thus, the gas sucked out before the measuring line allows the sampling line to be degassed. Thus, the measurement can be more precise, in particular when significant changes in concentration occur between two areas to be tested successively and when sufficient degassing time is required to obtain a measurement that is actually representative of the concentration in the test area.

[0068] Figure 3 A second embodiment of a measuring station 1 ′ is shown.

[0069] In this embodiment, the measuring station 1' comprises:

[0070] a first regulating electric valve 11 , which can be controlled by the sequencing unit 4 and is arranged at the input 7 of the regulating pump 3 ;

[0071] a first measuring electric valve 12 , which can be controlled by the sequencing unit 4 and is arranged at the input 9 of the at least one gas analyzer 2 ;

[0072] at least one second regulating electric valve 13 a , 13 b , which can be controlled by the sequencing unit 4 and is arranged as a branch from the first regulating electric valve 11 and the input 7 of the regulating pump 3 ; and

[0073] At least one second measuring electric valve 14 a , 14 b , which can be controlled by the sequencing unit 4 and is arranged as a branch from the first measuring electric valve 12 and the input 9 of the at least one gas analyzer 2 .

[0074] The first measuring electric valve 12 and the first regulating electric valve 11 are connected to the sampling line L1 .

[0075] The at least one second measuring electric valve 14 a , 14 b and the at least one second regulating electric valve 13 a , 13 b are connected to at least one sampling line L2 , L3 .

[0076] The example shown has three sampling lines L1-L3, i.e., two second regulating electric valves 13a, 13b are arranged as branches of the first regulating electric valve 11 and the input end 7 of the regulating pump 3, and two second measuring electric valves 14a, 14b are arranged as branches of the first measuring electric valve 12 and the input end 9 of the at least one gas analyzer 2.

[0077] The two second measuring electric valves 14 a , 14 b and the two second regulating electric valves 13 a , 13 b are connected to two corresponding sampling pipelines L2 , L3 .

[0078] For example, it is envisaged that the measuring station 1 ' according to this second embodiment comprises less than four second regulating electric valves and less than four second measuring electric valves, wherein the measuring station 1 is connected to a maximum of five sampling lines L1-L5. In practice, the number of electric valves required, beyond five, considerably increases the cost of the measuring station 1 '.

[0079] During operation, a sampling line, for example a single sampling line, whose measurement is programmed to follow the measurement of the sampling line being measured, is regulated while measurements are performed in the sampling line using the at least one gas analyzer 2 .

[0080] For example, by defining a sequencing procedure of the measurement of the concentration of the gaseous substance that must be performed in the sampling line L2 and subsequently the measurement in the sampling line L3 , the sampling line L3 is regulated while the measurement is performed in the sampling line L2 using the at least one gas analyzer 2 .

[0081] To this end, the sequencing unit 4 controls the connection between the sampling line L3 and the regulating pump 3 by opening the second sampling electric valve 13 b of the sampling line L3 and closing the second measuring electric valve 14 b of the sampling line L3 .

[0082] At the same time, the sequencing unit 4 controls the connection between the sampling line L2 and the at least one gas analyzer 2 by opening the second measuring electric valve 14a of the sampling line L2 and closing the second sampling electric valve 13a ( Figure 4 Step 101).

[0083] Then, after measuring in the sampling line L2, the sequencing unit 4 controls the connection between the sampling line L3 and the at least one gas analyzer 2 by opening the second measuring electric valve 14b of the sampling line L3 and closing the second measuring electric valve 13b of the sampling line L3 and the second measuring electric valve 14a of the sampling line L2.

[0084] At the same time, the sequencing unit 4 controls the connection between the sampling line and the regulating pump 3, for which the concentration of the gaseous substance must be continuously measured ( Figure 4 Step 102).

[0085] Thus, the operations can be continued until all the measurements defined in the sequencer are performed in order. These operations can be repeated as a loop.

Claims

1. A measuring station (1, 1') for measuring airborne molecular pollutants, comprising at least one gas analyzer (2) and a regulating pump (3), characterized in that: It also comprises a sequencing unit (4), the sequencing unit comprising a sequencing program, the sequencing program defining the order of measurements to be performed for at least two sampling lines (L1-L16), the sequencing unit (4) being configured to control the connection of the sampling line (L1-L16) to be measured, whose measurement is programmed to follow the measurement of the sampling line (L1-L16) being measured, to the regulating pump (3), and at the same time to control the connection of the sampling line (L1-L16) being measured to the at least one gas analyzer (2), the regulating pump (3) being configured to suck out gas in the sampling line before the sampling line is measured to allow the sampling line to be degassed, Wherein, the measuring station further comprises: - a sampling electric valve (5) on each sampling line (L1-L16), the sampling electric valve being controllable by the sequencing unit (4); - a first and a second regulating electric valve (6a, 6b), which can be controlled by the sequencing unit (4) and are arranged as branches of the input (7) of the regulating pump (3); - a first and a second measuring electric valve (8a, 8b), which can be controlled by the sequencing unit (4) and are arranged as branches of the input terminal (9) of the at least one gas analyzer (2), the first regulating electric valve (6a) and the first measuring electric valve (8a) being connected to the sampling electric valves (5) of the sampling lines (L1, L3, L5, L7, L9, L11, L13, L15) of a first series (S1), the second regulating electric valve (6b) and the second measuring electric valve (8b) being connected to the sampling electric valves (5) of the sampling lines (L2, L4, L6, L8, L10, L12, L14, L16) of a second series (S2), The sequencing program is designed so that the measurements to be performed are performed alternately in the sampling lines of each series (S1, S2).

2. The measuring station (1) according to the preceding claim, characterized in that The sequencing unit (4) is configured to control the connection of a single sampling line (L1-L16) to be measured, whose measurement is programmed to follow the measurement of the sampling line (L1-L16) being measured, to the regulating pump (3), and simultaneously to control the connection of the sampling line (L1-L16) being measured to the at least one gas analyzer (2).

3. The measuring station (1) according to claim 1, characterized in that It comprises at least five sampling electric valves (5).

4. The measuring station (1) according to any one of claims 1 or 3, characterized in that The first series (S1) of sampling lines comprises the same number of sampling lines as the second series (S2).

5. Method (100) for measuring airborne molecular pollutants by means of a measuring station (1, 1') according to any one of the preceding claims, characterized in that A sampling line (L1-L16) to be measured is regulated, wherein the measurement of the sampling line to be measured is programmed to be performed after the measurement of the sampling line (L1-L16) being measured, the sampling line to be measured (L1-L16) is connected to a regulating pump (3), and at the same time, at least one gas analyzer (2) is used to perform measurement in the sampling line (L1-L16) being measured.

6. The measuring method (100) according to the preceding claim, characterized in that The measurements to be performed are carried out alternately in each of the two series (S1, S2) of sampling lines, the sampling lines (L1, L3, L5, L7, L9, L11, L13, L15) of the first series (S1) being connected to a first regulating electric valve (6a) and a first measuring electric valve (8a), and the sampling lines (L2, L4, L6, L8, L10, L12, L14, L16) of the second series (S2) being connected to a second regulating electric valve (6b) and a second measuring electric valve (8b).

7. The measuring method (100) according to any one of claims 5 or 6, characterized in that: The sampling line (L1-L16) which is regulated and in which measurements are simultaneously performed using at least one gas analyzer (2) is a single line.

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