MEASUREMENT STATION AND METHOD FOR MEASURING PARTICLE CONTAMINATION IN A TRANSPORT ENCLOSURE FOR ATMOSPHERIC TRANSPORT AND STORAGE OF SEMICONDUCTOR WAFERS - Patent application

Abstract

A measurement station (1) for measuring particle contamination in a transport enclosure for atmospheric transport and storage of semiconductor wafers comprises a particle counter (5) and an interface (6) configured to be coupled to a shell (2) of the transport enclosure in place of a door (3), the interface (6) comprising a sampling orifice (7) fluidly connected to the particle counter (5). The measurement station (1) further comprises a clean gas injection device (15) comprising an injection line (16) having an injection nozzle (17) configured to be fluidly connected to a ventilation port (4) of the transport enclosure, the injection line (16) being configured to be fluidly connected to the ventilation port (4) of the transport enclosure coupled to the interface (6), and injecting clean gas into the transport enclosure from outside the transport enclosure through the ventilation port (4) of the transport enclosure.

Description

[Technical Field]

[0001] The present invention relates to a measurement station for measuring particle contamination in a transport enclosure for atmospheric transport and storage of semiconductor wafers, and also to a corresponding method for measuring particle contamination. [Background technology]

[0002] In the semiconductor manufacturing industry, transport enclosures, particularly standardized Front Opening Unified Pod (FOUP) wafer transport and storage enclosures, are used to transport silicon wafers from one tool to another or to store wafers between two manufacturing stages.

[0003] These transport enclosures are made of materials such as polycarbonate, which can sometimes accumulate contaminants, especially organic, amine, or acid contaminants. Silicon wafers are kept in these sealed enclosures for long periods of time. Therefore, it is essential to control contamination, especially particulate contamination, within these enclosures.

[0004] Patent Document 1 discloses a measurement device that includes a particle detector and an interface configured to be coupled to the shell of a transport housing instead of a door in order to determine whether the housing needs cleaning. In this device, an interface measurement head that includes a sampling orifice connected to the particle detector and an injection nozzle injects purge gas from inside the housing onto the wall of the shell, and peels off, samples, and counts particles that have adhered to the wall. This device makes it possible to determine the level of contamination on the internal surfaces of a transport enclosure, the walls of which may shed particles onto substrates contained within the transport enclosure when the transport enclosure is handled. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] WO2014 / 083151A1 Summary of the Invention [Problem to be solved by the invention]

[0006] However, it has become important to monitor other elements of the transport enclosure. Originally, the vents in the transfer enclosures fitted with particle filters were only required to balance the pressure inside and outside the enclosure, specifically to prevent air movement, such as air entering the enclosure from the cleanroom when the door was opened, but also to avoid pressure drops inside the enclosure that could create mechanical stresses that could become a source of contamination.

[0007] However, today these vents are used as inlet orifices for nitrogen or ultra-dry air to be injected into the enclosure to purge the interior and limit the presence of gaseous contaminants (airborne molecular contaminants, AMC), thereby ensuring acceptable production yields. Some of these vents are even more complex, with numerous additional elements in addition to filters, such as check valves and diffusers, which can generate particles that can clog the filters or cause leaks themselves.

[0008] As a result, if the vent filter is faulty or inadequate, the purge gas injected into the enclosure increases the risk of immediate contamination of the silicon wafers inside the enclosure.With the widespread practice of purging transfer enclosures through vents, particle filters are becoming a major source of contamination risk in transfer enclosures. However, existing solutions for monitoring particle contamination within transport enclosures are not suitable for determining contamination levels within ventilation filters.

[0009] Indeed, the use of ultra-clean water to loosen particles and then counting them in a liquid particle counter to determine concentration does not allow for fast testing, especially for monitoring particle concentration on filters. Even in the method described in Patent Document 1, in which clean air is injected into the transport housing to loosen the particles and then the particles are counted, it is not possible to specifically monitor the filter inside the housing.

[0010] Another measurement method involves using a test silicon wafer that has already been measured for particles using a particle measurement device specifically designed for wafers. The measured test wafer is placed in a transport enclosure, which is then connected to a purge station and a purge gas is injected through a port in the enclosure. The test silicon wafer is then removed from the enclosure, and the particle count on the wafer is performed using the measurement device, and the results are compared to the initial measurement. This measurement method is relatively time-consuming and costly, and is not efficient enough for automated production control. Furthermore, on-wafer particle measurement equipment is not always available due to the priority given to qualification testing of process equipment during production.

[0011] It is therefore one of the objects of the present invention to provide a station and a corresponding measurement method that allows the level of particle contamination of a particle filter in a ventilation opening of an atmospheric conveying enclosure to be measured in real time directly in the manufacturing plant. [Means for solving the problem]

[0012] To this end, the present invention relates to a measurement station for measuring particle contamination within a transport enclosure, in particular a FOUP enclosure, for atmospheric transport and storage of semiconductor wafers. The transport enclosure comprises a shell and a removable door by which the shell can be closed, the shell having at least one ventilation opening, for example 1 to 4 ventilation openings, equipped with a particle filter. The measurement station includes a particle counter and an interface configured to be coupled to the shell in place of the door, the interface including a sampling orifice fluidly connected to the particle counter.

[0013] The measurement station further includes a clean gas injection device having at least one injection line including at least one injection nozzle configured to be fluidly connected to a ventilation port of the transport housing, for injecting clean gas into the transport housing from outside the transport housing.

[0014] By injecting clean gas into the vents, production risk conditions can be simulated when purging the vent(s) in the transfer enclosure. If the particle filters in the vents cause particle contamination issues, this can be detected by measuring particles collected from a sampling orifice inside the transfer enclosure with a particle counter. The test conditions are the same as production conditions. Real-time particle measurement also makes it possible to maintain production rates.

[0015] The measuring station may also have one or more of the features described below, either individually or in combination. The sampling orifice is, for example, located in a measurement head that protrudes from the base of the interface. The measurement station may include a vacuum pump located downstream of the particle counter in a gas pumping direction. The particle counter is, for example, an aerosol particle counter. The particle counter is, for example, an optical type. The pumping flow rate of the vacuum pump is, for example, 30 liters / minute (1.8 m 3 / h or 0.0005m 3 / s).

[0016] To couple the transport housing to the measurement station and remove the door of the transport housing, the measurement station can include a chamber that houses the interface and has a lateral access, and a load port located below the access, which is coupled to the shell and door of the transport housing and allows the door of the transport housing to be moved into the chamber, thereby communicating the interior of the shell of the transport housing with the interior of the chamber.

[0017] The clean gas injection device may, for example, include injection nozzles in the same number as the number of ventilation openings in the transport housing. In another example, the clean gas injection device may include at least one plug configured to block the ventilation openings, such that all ventilation openings are configured to engage with injection nozzles or plugs. Alternatively, some ventilation openings may be left open. At least one injection nozzle is provided with a sealing device that provides an airtight connection with the ventilation opening, for example. The clean gas injection device may optionally include an actuator configured to press an injection nozzle or plug against the respective vent opening.

[0018] The clean gas injection device may include at least one pressure sensor configured to measure the pressure in the injection line. The clean gas injection device includes at least one flow control device, and is configured to control, for example, 30 liters per minute (0.0005 m 3 / sec) to 100 liters / minute (0.00167m 3 / sec), e.g., an average of 50 liters / minute (0.00083 m 3 / sec), up to 100 liters / minute (0.00167m 3 Different gas flows up to 1 / sec can be controlled. For example, there is one pressure sensor and one flow control device for each infusion line.

[0019] The present invention also relates to a method for measuring particle contamination in a transport enclosure for atmospheric transport and storage of semiconductor wafers, the method being carried out in the measurement station described above and comprising injecting clean gas into the transport enclosure from outside the transport enclosure through at least one ventilation opening in the transport enclosure, and counting particles in a gas sample taken through a sampling orifice in the interface during injection.

[0020] The measurement method of the present invention may also have one or more of the following characteristics, either individually or in combination: According to one embodiment of the present invention, the flow rate of the clean gas injected by the at least one injection nozzle is greater than the flow rate of the sample gas. For example, the flow rate of the clean gas injected into at least one injection nozzle is 6 liters / minute (0.0001 m 3 / sec), e.g. 30 liters / min (1.8m 3 / hour or 0.0005m 3 / sec), e.g. 50 liters / min (3m 3 / hour or 0.000833333m 3 / sec), e.g. 80 liters / min (4.8m 3 / hour or 0.00133333m 3 / second). Injecting clean gas at a flow rate higher than that of the sample gas and higher than that typically used to purge the transport enclosure under production conditions subjects the transport enclosure to slightly greater stress than during a purge operation, which makes it easier to remove particles from the particle filter and count them.

[0021] The clean gas is, for example, nitrogen or compressed air of ISO 8573-1 quality class 1 / 1 / 1. Table 1 shows the relationship between class and number of solid particles.

[0022] [Table 1]

[0023] According to one embodiment of the present invention, to measure particle contamination in a transport enclosure with multiple vents, clean gas is injected into all vents of the transport enclosure simultaneously, and the number of particles is counted during this injection, which allows the overall cleanliness level of the particle filters in the transport enclosure to be determined.

[0024] According to another embodiment of the invention, particle contamination in a transport enclosure with multiple vents is measured by injecting clean gas into the vents sequentially, either port by port, or grouping two or more ports together, and counting the number of particles at each injection. This sequencing makes it easier to identify problematic filters.

[0025] According to one embodiment of the present invention, by measuring the pressure in the injection line via a pressure sensor during injection of clean gas and comparing that pressure with a reference value obtained, for example, in an injection line without a fault, faults in vents, particularly those with abnormally high particle counts, are identified, and in particular whether this is due to a fault in the particle filter. A difference between the measured pressure and the reference value may indicate a malfunction in the vent. If the measured pressure is lower than the reference value, it may indicate a damaged particle filter in the vent or a leaking part of the clean gas injection device. If the measured pressure is higher than the reference value, it may indicate a malfunction in the valve in the vent. Other advantages and features of the present invention are contained in the description of non-limiting embodiments of the invention and in the accompanying drawings. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a perspective view of a particulate contamination measurement station coupled to a transport enclosure according to one embodiment of the present invention; [Figure 2] 2 is an enlarged view of the shell of the transport housing coupled to the measurement station of FIG. 1; [Figure 3] 2 is a schematic diagram of the components of the clean gas injection device and transfer housing (bottom view) of the measurement station of FIG. 1; [Figure 4] 1A and 1B are diagrams illustrating an example of a ventilation opening in a transport housing according to an embodiment of the present invention, showing the ventilation opening in an assembled state and in an exploded state. [Figure 5a] 1 is a schematic diagram of a measurement station and transport enclosure according to an embodiment of the present invention; [Figure 5b]5b is a view similar to FIG. 5a showing the load port of the measurement station coupled to the door of the transport enclosure; [Figure 5c] FIG. 5b is a view similar to FIG. 5b, showing the load port door and the housing door moved away from the access to the measurement station chamber. [Figure 5d] FIG. 5c is a view similar to FIG. 5c showing an interface coupled to the shell of the transport enclosure. [Figure 6] 1 is a graph of the pressure in the injection line measured as a function of time during injection of clean gas according to an embodiment of the present invention, showing the pressure in the injection line with a fault (solid line) and the pressure in the injection line without a fault (dashed line) of a clean gas injection device. DETAILED DESCRIPTION OF THE INVENTION

[0027] Embodiments of the present invention will now be described with reference to the drawings, in which identical elements are designated by the same reference numerals. The following embodiments are illustrative. Although one or more embodiments are referred to in this specification, this does not necessarily mean that each reference numeral refers to the same embodiment, or that each feature applies only to one embodiment. Individual features of different embodiments may be combined or interchanged to form other embodiments.

[0028] FIG. 1 shows a measurement station 1 for measuring particle contamination within a FOUP (Front Opening Unified Pod) wafer transport and storage enclosure. The transport enclosure has a sealed internal air or nitrogen atmosphere at atmospheric pressure, i.e., a pressure environment that is approximately the same as, but independent of, the operating environment of a clean room.

[0029] As shown in Figures 2 and 5a, each transport enclosure comprises a shell 2 and a removable door 3 that can close the shell 2, and the door 3 is dimensioned to allow wafers to be inserted and removed from the transport enclosure. The shell 2 and the door 3 are made of a material such as polycarbonate. The inner side walls, bottom wall and door 3 of the transport housing are provided with slots for holding wafers. The enclosure is relatively sealed, but only to the extent that a small leak occurs through a gasket located between the shell 2 and the door 3 .

[0030] 3 and 4, the shell 2 in the FOUP transport enclosure has at least one vent 4, for example, 1 to 4 vents 4, each vent 4 being fitted with a particle filter 4a to prevent particles from entering the transport enclosure. These vents 4 are located at the base of the shell 2 and, among other things, can balance the pressure inside and outside the transport enclosure to prevent air movement when the door of the transport enclosure is opened.

[0031] Each ventilation opening 4 may be formed by only one orifice with one particle filter 4a, allowing gas to flow in and out of the housing simultaneously and indiscriminately through each ventilation opening 4. Another example of a ventilation opening 4 may include one inlet / outlet check valve 4b located in each orifice upstream or downstream of the particle filter 4a. The outlet check valve of the inlet / outlet check valve 4b opens when the gas pressure inside the transport housing becomes excessively high relative to the external atmospheric pressure, and the inlet check valve opens when negative pressure is created inside the housing. The ventilation opening 4 may also include other elements, such as a gasket, a support element 4c, a diffuser 4d, or a grommet 4e.

[0032] As shown in Figure 5a, the measurement station 1 includes a particle counter 5 and an interface 6. The interface 6 is configured to be coupled to the shell 2 of a transport housing coupled to the measurement station 1 instead of the door 3. The interface 6 comprises a sampling orifice 7 which is fluidly connected via a sampling line to the particle counter 5. The sampling orifice 7 is, for example, located in a measurement head 8 which protrudes from the base of the interface 6, in which case the substrate is removed from the transport housing before the measurement is performed. The measurement station 1 may also comprise a vacuum pump 19 arranged downstream of the particle counter 5 in the gas pumping direction.

[0033] A gas sample is drawn from the measurement volume of the shell 2 connected to the interface 6 through a sampling orifice 7. The amount of particles contained in the drawn gas sample is measured by a particle counter 5. The particle counter 5 is, for example, an aerosol particle counter and provides quantitative information about the suspended particles in the gas environment. The particle counter 5 is, for example, optical, for example based on laser technology. The pumping speed of the vacuum pump 19 is, for example, 30 liters / min (1.8 m 3 / hour or 0.0005m 3 / second).

[0034] The measuring station 1 comprises a chamber 9 with a specially controlled environment for coupling the transport housing to the measuring station 1 and removing the door 3, in which the interface 6 is located. This chamber 9 is, for example, a clean room at atmospheric pressure. This chamber is, for example, ISO 3 certified according to the ISO 146644-1 "Minienvironment" standard. For this purpose, the chamber 9 can be equipped with a laminar flow filter unit 10.

[0035] According to an exemplary embodiment of the present invention, chamber 9 has a side access 11 and a load port 12 below side access 11. Load port 12 is coupled to transport housing shell 2 and door 3 such that transport housing door 3 can be moved into chamber 9 to place the interior of shell 2 in communication with the interior of chamber 9. For this purpose, the loading port 12 is provided with a platform 13 for receiving and positioning the transport housing, which may be equipped with a presence sensor configured to verify whether the model of the transport housing is compatible with the measuring station 1 that receives the housing. Furthermore, the platform 13 of the loading port 12 comprises fixing means for clamping the shell 2 and then translating said shell (see arrow D1 in FIG. 5 a) relative to the access 11 of the chamber 9 for coupling with said shell 2. According to another example (not shown), the loading port 12 comprises moving means configured to move the fixing means from said loading port 12 towards the housing.

[0036] The load port 12 also includes a load port door 14, which is approximately the same size as the door 3 of the transport enclosure. The load port door 14 closes the access 11 to the chamber 9 when the transport enclosure is not present. The load port door 14 also includes a bolt actuation means for locking and unlocking the locking member of the door 3. The locking member of the door 3 is well known and is, for example, a latch attached to the door 3. This locking member is actuated by a radial or lateral slide and engages with the shell 2 of the transport housing when the transport housing is closed. When the locking member is released, the bolt actuation means reversibly secures the transport housing door 3 to the load port door 14. The door 3 and the load port door 14 can then be moved as a single unit from the front region of the access 11 into the chamber 9 via the actuation mechanism of the load port door 14.

[0037] The interface 6 can then be coupled to the shell 2 in place of the door 3, placing the sampling orifice 7 connected to the particle counter 5 in fluid communication with the interior volume of the shell 2. The shell 2 and the interface 6 thus form a single "transport enclosure." The measuring station 1 also comprises a clean gas injection device 15 with at least one injection line 16 . The injection line 16 includes at least one injection nozzle 17 configured to be fluidly connected to a ventilation port 4 of the transport housing coupled to the interface 6, and injects clean gas into the transport housing from outside the transport housing through the ventilation port 4 of the transport housing.

[0038] The injection nozzle 17 protrudes from the platform 13 at a position on the platform 13, for example, so that the injection nozzle 17 is positioned opposite the ventilation opening 4 of the transport housing after the shell 2 is fixed to the interface 6. The injection nozzle 17 is designed to engage with the opening of the ventilation opening 4 of the transport housing, for example. The clean gas injection device 15 includes injection nozzles 17, the number of which is equal to the number of ventilation openings 4 on the transport housing, for example.

[0039] According to another example, the clean gas injection device 15 comprises at least one plug configured to close the vent openings 4, for example, all the vent openings 4 are engaged with one injection nozzle 17 or one plug. Alternatively, some of the ventilation openings 4 may be left open. The injection nozzle 17 is for example provided with a respective sealing device providing an airtight connection with the ventilation opening 4. This sealing device is made of an elastic material, for example silicone. The sealing device may be, for example, a suction cup, a ring gasket, a lip seal, or a bellows that surrounds the orifice of the injection nozzle 17 . Alternatively, the sealing device may be made of a rigid material such as PEEK, and the seal may be achieved by compressing the sealing device.

[0040] The clean gas injection device 15 may optionally comprise multiple injection nozzles 17 or one actuator configured to press one or more plugs against each vent 4 . An injection line 16 connecting an injection nozzle 17 is connected to a gas source (also called a "facility") 18, such as a gas outlet available on-site. The injection line 16 may also be fitted with a particle filter 20 (see FIG. 3) for filtering contaminant particles from the injected clean gas. The clean gas may be, for example, nitrogen, pure dry air, or ultra-dry air. The injection flow rate of the clean gas into each injection nozzle 17 is, for example, 6 liters / minute (=0.0001 m 3 / sec) ~ 30 liters / minute (= 1.8m 3 / hour or 0.0005m 3 / second).

[0041] The clean gas injection device 15 may also comprise at least one pressure sensor 21 configured to measure the pressure in the injection line 16 (see FIG. 3 ), thereby enabling a fault in the vent 4, for example a fault in the particle filter 4a, to be identified by measuring the pressure in the injection line 16 and comparing it with a reference value. The clean gas injection device 15 includes at least one flow rate control device 22 (see FIG. 3) and is capable of controlling and injecting different gas flows into one injection line 16. For example, 30 liters / minute (=0.0005 m 3 / sec) ~ 100 liters / minute (=0.00167m 3 / sec), for example, an average of 50 liters / minute (=0.00083m 3 / sec), up to 100 liters / minute (=0.00167m 3 It is possible to inject gas flows in the range of 1 / sec.

[0042] For example, one pressure sensor 21 and one flow control device 22 are provided for each injection line 16. The pressure sensor 21 is arranged downstream of the flow control device 22 and the particle filter 20 in the flow direction of the clean gas in the injection line 16. Advantageously, the pressure sensor is arranged as close as possible to the ventilation opening 4 in order to improve the measurement sensitivity (see FIG. 3).

[0043] The control means of the transport enclosure model, the bolt drive means, the drive mechanism of the load port door 14 and the clean gas injection device 15 may be controlled by a processing device 23 (eg a computer or controller) of the measurement station 1 . This processing unit 23 may be connected to a user interface 24, which may comprise, for example, a screen and a keyboard, as shown in FIG.

[0044] The measuring station 1 comprises, for example, an electrical cabinet 25 for powering and housing some or all of the electrical components of the station. The electrical cabinet 25 is advantageously positioned laterally offset from the chamber 9 so as to be away from the laminar flow of filtered air, thereby preventing contamination of the chamber 9 by the various components housed in the electrical cabinet 25.

[0045] The method for measuring particle contamination of a transport enclosure for atmospheric transport and storage of semiconductor wafers, which is carried out at the measurement station 1, includes the steps described below. First, when the measuring station 1 is in the idle position, as shown in FIG. 5 a, the interface 6 is located in the chamber 9 and its access 11 is closed by the load port door 14 . Next, an operator or robot places the transport housing on the platform 13 of the loading port 12, which positions and checks the transport housing model, clamps the shell 2 of the transport housing, and moves this shell 2 towards the access 11 of the chamber 9, as shown by arrow D1 in Figure 5a.

[0046] Next, the bolt actuation means of the load port door 14 releases the locking member of the door 3 and rigidly connects the door 3 to the load port door 14, as shown in FIG. 5b. Door 3 and load port door 14 are then moved away from access 11 and into chamber 9, as indicated by arrow D2 in FIG. 5b, so that the interior volume of shell 2 communicates with the interior volume of chamber 9.

[0047] Next, as shown by arrow D3 in Fig. 5c, the interface 6 moves towards the shell 2, and as shown in Fig. 5d, the interface 6 is coupled to the shell 2 instead of the door 3. In this coupled state, the measurement head 8 is fixed within the measurement volume defined by the interface 6 and the coupled shell 2. Next, clean gas is injected into the transport housing from outside the transport housing through the ventilation port 4 of the transport housing, and during this injection, particles in a gas sample collected from the sampling orifice 7 of the interface 6 are counted (in real time / simultaneously). A sample of this gas is drawn through the sampling line and taken from the measurement volume, and the amount of particles contained in the sample of gas is continuously measured by the particle counter 5.

[0048] Injecting clean gas into vent 4 simulates the manufacturing risk conditions associated with purging the transport enclosure through this vent 4. If the particle filter 4a of this ventilation opening 4 causes a problem of particle contamination, this problem can be detected by measuring with a particle counter 5 using particles collected from inside the transport enclosure. The test conditions are the same as production conditions. Real-time particle counting also allows production rates to be maintained.

[0049] According to one embodiment of the present invention, the flow rate of the clean gas injected by the at least one injection nozzle 17 is greater than the flow rate of the sample gas. For example, the flow rate of the clean gas injected into at least one injection nozzle 17 is 6 liters / minute (=0.0001 m 3 / sec), for example, 30 liters / minute (=1.8m 3 / hour, or 0.0005m 3 / sec), e.g., 50 liters / minute (=3m 3 / hour, or 0.000833333m 3 / sec), e.g., 80 liters / minute (=4.8m 3 / hour, or 0.00133333m 3 / second). When the clean gas is injected at a flow rate higher than that of the sample gas and higher than that typically used to purge the transport enclosure under production conditions, the transport enclosure is subjected to slightly greater stress than during a purge operation. This makes it easier to separate and count particles from the particle filter 4a. The injection time of the clean gas is, for example, one minute for each injection nozzle 17 .

[0050] According to one embodiment of the present invention, clean gas is injected simultaneously into all ventilation openings 4 of the transport enclosure and the particle count is measured during this injection. In this way, the overall cleanliness level of the particle filters 4a in the transport enclosure can be determined.

[0051] According to another embodiment of the invention, clean gas is injected into the vents 4 sequentially, either port by port, or two or more ports simultaneously, and the particle count is counted after each injection. This sequencing allows problematic vents 4 to be identified.

[0052] According to one embodiment of the present invention, a fault in one vent 4, in particular one vent 4 with an abnormally high particle count, is identified and, in particular, it is determined whether this fault is due to a fault in the particle filter 4 a by measuring the pressure in the injection line 16 via the pressure sensor 21 during injection of clean gas and comparing this measured pressure with a reference value obtained with a fault-free injection line 16, determined, for example, during adjustment or by calculation.

[0053] A difference between the measured pressure and the reference value may indicate a malfunction of the vent 4. If the measured pressure is lower than the reference value, for example less than 20% of the reference value, this may indicate damage to the particle filter 4a of the vent 4 or a leak in an element of the clean gas injection device 15. If the measured pressure is higher than the reference value, this may indicate a malfunction of the valve 4b of the vent 4. In fact, when clean gas is injected into the vent 4 through the injection nozzle 17, the particle filter 4a "throttles" the flow of clean gas, resulting in an increase in the stable pressure during steady injection. If the particle filter 4a is damaged, misplaced or missing, this pressure will stabilize at a lower value.

[0054] This is illustrated in the graph of Figure 6, which shows the pressure measured as a function of time from the start of injection t0 in an injection line 16 with a fault (solid line) and an injection line 16 without a fault (dashed line). The graph shows that the pressure measured in the injection line 16 is significantly lower than the baseline value for a non-faulty injection line 16, at least 20% lower, and in this case almost 50% lower, which may indicate a fault in the particle filter 4a of the vent 4. Once the contamination measurement is complete, the interface 6 is removed from the shell 2, the transport enclosure is closed, released and sent for cleaning or depending on its cleanliness the wafer transport or storage operation continues. [Explanation of symbols]

[0055] 1 Measuring Station 2 shells 3 Removable Doors 4 Ventilation vents 4a Particle filter 5 Particle Counter 6 Interface 7 Sampling Orifice 9 Chamber 13 Platform 14 Loading port door 15 Clean gas injection device 16 Infusion Line 17 Injection nozzle 21 Pressure Sensor

Claims

1. A measuring station (1) for measuring particle contamination in a transport enclosure for atmospheric transport and storage of semiconductor wafers, comprising: The transport housing comprises a shell (2) and a removable door (3) by which the shell (2) can be closed, the shell (2) having at least one ventilation opening (4) equipped with a particle filter (4a), the measuring station (1) comprising a particle counter (5) and an interface (6) configured to be coupled to the shell (2) in place of the door (3); the interface (6) comprises a sampling orifice (7) fluidly connected to the particle counter (5); The measuring station (1) further comprises a clean gas injection device (15) having at least one injection line (16), the injection line (16) having at least one injection nozzle (17) configured to be fluidly connected to the ventilation port (4) of the transport housing coupled to the interface (6), and configured to inject clean gas into the transport housing from outside the transport housing through the at least one ventilation port (4) of the transport housing.

2. 2. The measuring station for measuring particle contamination in a transport enclosure according to claim 1, characterized in that the clean gas injection device (15) comprises at least one pressure sensor (21) configured to measure the pressure in the injection line (16).

3. 3. A method for measuring particle contamination of a transport enclosure for atmospheric transport and storage of semiconductor wafers, carried out in the measuring station (1) according to claim 1 or 2, comprising: A method for measuring particle contamination in a transport housing, comprising: injecting clean gas into the transport housing from outside the transport housing through at least one ventilation opening (4) in the transport housing; and counting the particles in a sample of the gas taken through the sampling orifice (7) of the interface (6) during the injection of the clean gas.

4. 4. The method for measuring particle contamination of a transport enclosure according to claim 3, characterized in that the flow rate of the clean gas injected by the at least one injection nozzle (17) is greater than the flow rate of the sample gas.

5. The flow rate of the clean gas injected into at least one of the injection nozzles (17) is 0.0001 m ３ 5. The method of claim 4, wherein the particle contamination of a transport enclosure is greater than 1 / s.

6. 4. The method for measuring particle contamination of a transport enclosure according to claim 3, wherein the clean gas is nitrogen or pure dry air.

7. The method for measuring particle contamination of a transport enclosure according to claim 3, characterized in that the transport enclosure has a plurality of ventilation openings (4), the clean gas is injected into all of the plurality of ventilation openings (4) of the transport enclosure simultaneously, and the number of particles is counted during the injection of the clean gas.

8. The method for measuring particle contamination of a transport enclosure according to claim 3, characterized in that the transport enclosure has a plurality of ventilation openings (4), the clean gas is injected into the plurality of ventilation openings (4) in turn, and the number of particles is counted during the injection of the clean gas.

9. 4. The method for measuring particle contamination in a transport enclosure according to claim 3, characterized in that a fault in the ventilation opening (4) is identified by measuring the pressure in the inlet line (16) and comparing the pressure with a reference value.

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