Cleanliness monitor and method for monitoring cleanliness of a vacuum chamber

Abstract

A cleanliness monitor, an evaluation system, and a method. The cleanliness monitor can include a first vacuum chamber, a second vacuum chamber, a molecular collector, a release unit, a mass spectrometer, a manipulator configurable to move the molecular collector from a first position to a second position, and an analyzer. The mass spectrometer can have a line of sight to an interior space of the second vacuum chamber. The mass spectrometer can be configured to monitor the interior space of the second vacuum chamber and generate a detection signal indicative of contents of the interior space of the second vacuum chamber. A first subset of the detection signal can be indicative of a presence of at least a subset of the released organic molecules. The analyzer can be configured to determine a cleanliness of at least one of (a) the first vacuum chamber and (b) a vacuum chamber under test based on the detection signal. The vacuum chamber under test is fluidically coupled to the first vacuum chamber.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to US 16 / 879,105, filed May 20, 2020. The disclosure of that application is hereby incorporated herein by reference in its entirety and for all purposes. Background Technology

[0003] Molecular contamination is a fundamental problem in semiconductor manufacturing, especially in tools that include vacuum chambers, such as scanning electron microscopes.

[0004] Organic molecules may originate from organic components inside the vacuum chamber, as well as from wafers previously inserted into the vacuum chamber.

[0005] These organic molecules adsorb onto the surface of the wafer being inspected and can form small islands covering a portion of the surface.

[0006] These islands can cause chip failure.

[0007] The cleanliness level of the vacuum chamber may vary over time due to maintenance activities and the level of gas release from the wafer being inspected.

[0008] There is an increasing need for a cleanliness monitor and a method for monitoring the cleanliness of vacuum chambers. Summary of the Invention

[0009] As shown in this application, a cleanliness monitor, an evaluation system, and a method are provided.

[0010] According to some embodiments, a cleanliness monitor includes: a first vacuum chamber, a second vacuum chamber, a mass spectrometer, a molecular collector, a release unit, a manipulator, and an analyzer. The molecular collector may be configured to collect organic molecules present in the first vacuum chamber during an accumulation cycle and when located in a first position within the first vacuum chamber to provide accumulated organic molecules. The release unit may be configured to trigger the release of at least a subset of the accumulated organic molecules toward the mass spectrometer during a release cycle and when the collector is located in a second position within the second vacuum chamber to provide released organic molecules. The manipulator may be configured to move the molecular collector from the first position to the second position. The mass spectrometer may have a line of sight to the interior space of the second vacuum chamber and may be configured to monitor the interior space of the second vacuum chamber and generate a detection signal indicating the contents of the interior space of the second vacuum chamber, wherein a first subset of the detection signal indicates the presence of released organic molecules. The analyzer may be configured to determine, based on the detection signal, the cleanliness of (a) the first vacuum chamber and (b) at least one of a test vacuum chamber fluidly coupled to the first vacuum chamber. Attached Figure Description

[0011] The subject matter regarded as the embodiments of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. The embodiments of the present disclosure, however, can be best understood from the following description in conjunction with the accompanying drawings taken into consideration together with the

[0012] Figure 1 An example of a cleanliness monitor is shown;

[0013] Figure 2 An example of a cleanliness monitor is shown;

[0014] Figure 3 An example of an evaluation system is shown;

[0015] Figure 4 An example of an evaluation system is shown; and

[0016] Figure 5 An example of a method is shown. DETAILED DESCRIPTION

[0017] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. However, it will be understood by those skilled in the art that the present embodiments of the present disclosure can be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the current embodiments of the present disclosure.

[0018] The subject matter regarded as the embodiments of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. The embodiments of the present disclosure, however, can be best understood from the following description in conjunction with the accompanying drawings taken into consideration together with the

[0019] It will be understood that the elements shown in the figures are not necessarily to scale, for illustrative clarity and simplicity. For example, the dimensions of some of the elements shown in the figures can be exaggerated relative to other elements for clarity. Also, where considered appropriate, reference numerals can be repeated among the figures to indicate corresponding or analogous elements.

[0020] Because most of the illustrated embodiments of the present disclosure can be implemented using electronic components and circuits known to those skilled in the art, in order to understand and appreciate the basic concepts of the present embodiments and in order not to obscure or distract from the teachings of the present embodiments, details will not be explained to a degree that is considered necessary beyond that shown, as above.

[0021] Any reference in this specification to a method should be regarded as referring mutatis mutandis to a system capable of performing the method.

[0022] Any reference in this specification to a system should be regarded as referring mutatis mutandis to a method performable by the system.

[0023] Any reference in this specification to the term "comprising" or "having" should be regarded as referring mutatis mutandis to "consisting of" or "consisting essentially of". For example, a method comprising certain steps can comprise additional steps, can be limited to certain steps, or can comprise additional steps respectively that do not materially affect the basic nature and novel characteristics of the method.

[0024] The phrases "within the vacuum chamber" and "within the inner space of the vacuum chamber" are used in an interchangeable manner.

[0025] A cleanliness monitor can be provided. The cleanliness monitor can comprise a first vacuum chamber, a second vacuum chamber, a molecule collector, a release unit, a manipulator, a mass spectrometer, and an analyzer.

[0026] The molecule collector can be configured to accumulate organic molecules present in the first vacuum chamber during an accumulation period and when located in a first position within the first vacuum chamber. The organic molecules accumulated by the molecule collector are referred to as accumulated organic molecules.

[0027] The first vacuum chamber can be fluidically coupled to a vacuum chamber under test of an evaluation system.

[0028] The evaluation system can be an inspection system, a metrology system, an review system, etc. The organic molecules in the first vacuum chamber can be emitted from the vacuum chamber under test. The vacuum chamber under test is tested in the sense that the cleanliness of the vacuum chamber under test is tested by the cleanliness monitor.

[0029] The release unit can be configured to cause release of at least a subset of the accumulated organic molecules towards the mass spectrometer during a release period and when the collector is located in a second position within the second vacuum chamber. The at least a subset of the accumulated organic molecules are referred to as released organic molecules.

[0030] The manipulator can be configured to move the molecule collector between the first position and the second position.

[0031] The mass spectrometer can have a line of sight to the inner space of the second vacuum chamber. The mass spectrometer can be configured to monitor the inner space of the second vacuum chamber and to generate a detection signal indicative of the content of the inner space of the second vacuum chamber. A first subset of the detection signal can be indicative of the presence of at least a subset of the accumulated organic molecules.

[0032] The analyzer can be configured to determine the cleanliness of the first vacuum chamber based on the detection signal. Alternatively or additionally, the analyzer can be configured to determine the cleanliness of the vacuum chamber under test based on the detection signal.

[0033] The volume of the interior space of the first vacuum chamber can be greater than the volume of the interior space of the second vacuum chamber. For example, the volume of the interior space of the first vacuum chamber can be at least 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 (and even more) times greater than the volume of the interior space of the second vacuum chamber.

[0034] The smaller volume of the interior space of the second vacuum chamber increases the sensitivity of the mass spectrometer because the concentration of the accumulated organic molecules in the interior space of the second vacuum chamber exceeds the concentration of the accumulated organic molecules in the interior space of the first vacuum chamber.

[0035] Performing the release of the accumulated organic molecules in the second vacuum chamber and not in the first vacuum chamber thereby increases the cleanliness of the first vacuum chamber. The increase in the cleanliness of the first vacuum chamber can be more pronounced when the second vacuum chamber is isolated from the first vacuum chamber or at least substantially isolated from the first vacuum chamber.

[0036] The separation between the first vacuum chamber and the second vacuum chamber during the release period also allows more time and / or more resources to be allocated to the release period because the release process does not contaminate the first vacuum chamber.

[0037] The separation between the first vacuum chamber and the second vacuum chamber during the release period can be achieved by using a molecular collector and a manipulator. This can simplify the system comprising the monitoring system and reduce the cost of manufacturing the system.

[0038] The manipulator can comprise a moving mechanism and a bellow.

[0039] The moving mechanism can be configured to move the molecular collector between the first position and the second position.

[0040] The moving mechanism can be mechanically coupled between the molecular collector and the first vacuum chamber.

[0041] The moving mechanism can be any mechanical mechanism capable of moving the molecular collector between the first position and the second position. The moving mechanism can perform linear movement, non-linear movement, etc. The moving mechanism can be a piston; a rotary unit; any combination of one or more motors, one or more gears, one or more joints, etc.

[0042] The bellow can be configured to isolate the moving mechanism from the interior space of the first vacuum chamber at least during movement between the first position and the second position. The isolation can prevent the interior space of the first vacuum chamber from being contaminated by the moving mechanism.

[0043] The cleanliness monitor can comprise a flow control unit, which can be configured to influence the propagation of at least a subset of the aggregated molecules during the release period.

[0044] After the release period, the molecule collector can be moved within the interior space of the first vacuum chamber in order to perform a further aggregation of organic molecules.

[0045] Since the first vacuum chamber is separated from the second vacuum chamber, and since the pressure level within the second vacuum chamber can deviate from the pressure level of the first vacuum chamber at least during the release period, it is necessary to equalize the pressure level of the second vacuum chamber with the pressure level of the first vacuum chamber before moving the molecule collector back into the first molecule collector.

[0046] The flow control unit can be configured to compare the pressure within the interior space of the second vacuum chamber with the pressure within the interior space of the first vacuum chamber after the end of the release period.

[0047] The flow control unit can comprise a turbomolecular pump and a valve. The valve can be configured to be closed during the monitoring period. The valve can be configured to fluidically couple the interior space of the second vacuum chamber to the turbomolecular pump during at least a portion of the release period. Any other combination of flow control can be used.

[0048] The cleanliness monitor can comprise a first opening, which can be shared by the first vacuum chamber and the second vacuum chamber. The manipulator can be configured to move the molecule collector through the first opening while moving the molecule collector between the first position and the second position.

[0049] The cleanliness monitor can comprise a second opening, which can be shared by the first vacuum chamber and the vacuum chamber under test.

[0050] The release unit can comprise a heating element, which is thermally coupled to the molecule collector.

[0051] Figure 1 An example of a cleanliness monitor 200 is shown.

[0052] The cleanliness monitor 200 can be used as a stand-alone unit for monitoring and measuring the cleanliness of equipment operating within a vacuum chamber under test.

[0053] The cleanliness monitor 200 can comprise a first vacuum chamber 201, which can be fluidically coupled to a vacuum chamber under test 301.

[0054] Modules (e.g., metrology modules, inspection modules, defect review, etc.) can be permanently or temporarily located within a vacuum chamber under test. The modules can be scanning electron microscopes, transmission electron microscopes, critical dimension scanning electron microscopes, defect review scanning electron microscopes, ion mills, charged particle imagers, etc.

[0055] The cleanliness monitor 200 can further comprise a second vacuum chamber 202, a molecule collector 207, a release unit, a manipulator 222, a mass spectrometer 21 and an analyzer 223.

[0056] The second vacuum chamber 202 can be mechanically coupled to the first vacuum chamber 201.

[0057] The release unit can comprise a heater 208 and a flow control unit 221.

[0058] The flow control unit 221 can comprise a vacuum transducer 203, a pumping line 212, a turbo molecular pump 204, a roughing pump 206 and a valve 205.

[0059] Figure 1 The molecule collector 207 is shown at a first position within an inner space of the first vacuum chamber 201.

[0060] The molecule collector 207 can be moved by the manipulator 222. The manipulator 222 can comprise a moving mechanism, such as a pneumatic cylinder 210 controlled by a mechanical valve 211. The mechanical valve 211 can be controlled by a control signal from a controller 225.

[0061] The controller 225 can belong to the cleanliness monitor or can belong to the module.

[0062] A bellows 209 is mounted between the molecule collector 207 and a flange 213. The flange 213 is mounted inside the first vacuum chamber 201. The flange 213 is an example of a mechanical element mechanically coupling the bellows 209 to the first vacuum chamber 201.

[0063] The bellows 209 is configured to isolate the inner space of the first vacuum chamber 201 and the molecule collector 207 from the manipulator 222.

[0064] In Figure 1 the heater 208 is mechanically and thermally coupled to the molecule collector 207.

[0065] The molecule collector 207, when located in the inner space of the first vacuum chamber 201, is configured to accumulate organic molecules in the inner space of the first vacuum chamber 201. The organic molecules can originate from a vacuum chamber under test fluidically coupled to the first vacuum chamber.

[0066] The duration of the aggregation period can depend on the attachment period of the organic molecules. The attachment period can be measured or estimated. Different organic molecules can exhibit different attachment periods.

[0067] The duration of the aggregation period can be determined based on one or more attachment periods of the one or more organic molecules.

[0068] For example, the duration of the aggregation period can be set based on an average attachment period of the one or more organic molecules.

[0069] For example, the duration of the aggregation period can be set based on a weighted sum of one or more aggregation periods of the one or more organic molecules.

[0070] For example, the duration of the aggregation period can be set based on an average attachment period of the one or more organic molecules.

[0071] For example, the aggregation period can range between half an hour and a month, less than an hour, more than a month, etc.

[0072] At the end of the aggregation period, the controller can control the gas cylinder 210 to move the molecule collector 207 to a second position within the interior space of the second vacuum chamber 202.

[0073] Figure 2 The molecule collector 207 is shown positioned at the second position within the interior space of the second vacuum chamber 202. The molecule collector 207 and the manipulator 222 separate the interior space of the first vacuum chamber from the interior space of the second vacuum chamber.

[0074] When the molecule collector 207 is positioned within the interior space of the second vacuum chamber 202, the release unit can perform a release process for releasing the aggregated organic molecules from the molecule collector 207. The released organic molecules are referred to as released organic molecules.

[0075] The release process of the aggregated organic molecules from the surface of the molecule collector 207 can include at least one of (a) heating the molecule collector 207 using the heater 208 and (b) measuring the released molecules by the mass spectrometer.

[0076] The released organic molecules can be evacuated from the second vacuum chamber 202 after the measurement. It can be beneficial to release all of the aggregated organic molecules from the molecule collector 207.

[0077] The duration of the release period can be significantly shorter than the aggregation period and can depend on the surface temperature of the molecule collector 207, the concentration of the aggregated organic molecules on the surface, the volume of the second vacuum chamber in the release position, and the distance between the molecule collector 207 and the mass spectrometer 21.

[0078] During the release period, the pressure in the second vacuum chamber 202 can increase. The pressure in the second vacuum chamber 202 can be measured by the vacuum transducer 203. At the end of the measurement period, the released organic molecules can be evacuated.

[0079] The evacuation of the released organic molecules can be done before comparing the pressure level in the first vacuum chamber with the pressure level in the second vacuum chamber.

[0080] The evacuation of the released organic molecules can be performed in parallel with comparing the pressure level in the first vacuum chamber with the pressure level in the second vacuum chamber.

[0081] The comparison of the pressure levels and / or the evacuation of the released organic molecules can be performed by the flow control unit 221.

[0082] The valve 205 of the flow control unit 221 can fluidly couple the turbo molecular pump 204 of the flow control unit 221 with the second vacuum chamber 202. The turbo molecular pump 204 can be configured to increase the vacuum level in the second vacuum chamber 202.

[0083] After the pressure in the second vacuum chamber is equal to the pressure within the first vacuum chamber, the pressure in the second vacuum chamber should be maintained, for example, by closing the pumping line 212 with the valve 205. In addition, the molecular collector 207 can be cooled by the cooling unit located within the space defined by the bellows 209. The molecular collector 207 can be moved to the first position after cooling the molecular collector 207.

[0084] The cleanliness monitor 200 can exhibit a high sensitivity to organic molecules and can achieve a high purity of molecular contamination because the released organic molecules are removed from the second vacuum chamber.

[0085] Figure 3 and Figure 4 An example of an evaluation system 300 comprising a vacuum chamber under test 301 and a cleanliness monitor 200 is shown.

[0086] A module, such as but not limited to an evaluation module (not shown), can be located within the vacuum chamber under test 301.

[0087] The first vacuum chamber 201 of the cleanliness monitor 200 is fluidly coupled to the vacuum chamber under test 301 via a second opening denoted 302. Figure 3 The first vacuum chamber 201 and the vacuum chamber under test 301 can be fluidly coupled to each other in any other way.

[0088] In Figure 3 The molecular collector 207 is in its first position.

[0089] In Figure 4In some embodiments, the molecular collector is in its second position.

[0090] Figure 3 and Figure 4 It is also shown that the plasma source 310 is configured to clean the vacuum chamber under test 301.

[0091] Figure 4 It is shown that the manipulator 222 is configured to isolate the mass spectrometer 21 from the plasma and to increase the lifetime of the mass spectrometer 21.

[0092] Figure 5 The method 500 is shown in accordance with embodiments of the present disclosure.

[0093] The method 500 can start with the step 510 of accumulating organic molecules present in a first vacuum chamber by a molecular collector to provide accumulated organic molecules.

[0094] The accumulation of the organic molecules can be performed during an accumulation period and when the molecular collector is located at a first position within the first vacuum chamber. The first vacuum chamber can be fluidically coupled to a vacuum chamber under test and to a second vacuum chamber. The accumulation results in accumulated organic molecules.

[0095] The step 510 can be followed by the step 520 of moving the molecular collector from the first position to a second position within the second vacuum chamber.

[0096] The step 520 can be followed by the steps 530 and 540.

[0097] The step 530 can comprise inducing a release of at least a subset of the accumulated organic molecules by a release unit and during a release period to provide released organic molecules. The released organic molecules can be directed towards a mass spectrometer.

[0098] The step 540 can comprise monitoring, by the mass spectrometer, an inner space of the second vacuum chamber and generating, by the mass spectrometer, a detection signal indicative of contents of the inner space of the second vacuum chamber.

[0099] A first subset of the detection signal can be indicative of a presence of the released organic molecules.

[0100] The steps 530 and 540 can be followed by the steps 550 and 560.

[0101] The step 550 can comprise evacuating any released organic molecules from the second vacuum chamber.

[0102] The step 560 can comprise determining, by the analyzer and based on the detection signal, a cleanliness of at least one of (a) the first vacuum chamber and (b) a vacuum chamber under test fluidically coupled to the first vacuum chamber.

[0103] Step 560 can include comparing the detection signals obtained during the accumulation period to the detection signals obtained during the release period. The comparison can include comparing spectral elements representative of components of the same atomic mass.

[0104] The comparison can include comparing only spectral components having certain atomic masses, such as atomic masses of the organic molecules or atomic masses of molecules resulting from fragmentation of the organic molecules during the mass spectrometer process.

[0105] Step 560 can include determining the cleanliness of the vacuum chamber under test based on the cleanliness of the first vacuum chamber. The relationship between the cleanliness of the first vacuum chamber and the cleanliness of the vacuum chamber under test can be calculated or tested in any manner.

[0106] For example, the relationship can be determined based on the manner in which the cleanliness of the first vacuum chamber and the cleanliness of the vacuum chamber under test are fluidly coupled to one another.

[0107] For example, the cleanliness of the first vacuum chamber can be measured multiple times and independently of the measurement of the cleanliness of the vacuum chamber under test to provide multiple cleanliness results for both vacuum chambers. The relationship can be calculated based on the multiple cleanliness results for both vacuum chambers. Non-limiting examples of calculations can include a correlation, a matching algorithm, etc.

[0108] Note that the method 50 can be repeated multiple times in a periodic or non-periodic manner.

[0109] In the foregoing specification, embodiments of the disclosure have been described with reference to specific examples thereof. It will, however, be evident that various modifications and changes can be made thereto without departing from the broader spirit and scope of embodiments of the disclosure as set forth in the appended claims.

[0110] Also in the description, where a term is used in the singular, plural forms can be included in the term unless explicitly stated otherwise. Also, the terms "front," "back," "top," "bottom," "over," "under," and the like in the description are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable with respect to the embodiments described herein, and that for purposes of description here, a structure described as being positioned or arranged in an orientation is positioned or arranged in that orientation unless otherwise stated.

[0111] Any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as "associated with" each other such that the desired functionality is achieved, irrespective of architectures or intermediate components. Likewise, any two components so associated can also be viewed as being "operably connected," or "operably coupled," to each other to achieve the desired functionality.

[0112] In addition, those skilled in the art will recognize that the boundaries between these operations are merely illustrative. The multiple operations can be combined into a single operation, a single operation can be distributed in additional operations and operations can be executed at least partially overlapping in time. Moreover, alternative embodiments can include multiple instances of a particular operation, and the order of operations can be altered in various other embodiments.

[0113] However, other modifications, changes and substitutes are possible. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive sense.

[0114] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. Further, as used herein, the term "and / or" comprises any and all combinations of one or more of the associated listed items. Yet further, the use of any of the verbiage "comprising", "comprise", "having", "including", "includes" or "with" is used herein to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. In the claims, the article "a" is intended in the alternative (that is "or" as it is used in the common and dictionary sense) not in the alternative of "only one of individually following the additional limitations in the claims. The terms "first", "second" and other such numerical terms refer to different or additional ones of the elements to which they refer, not to an order or priority. Accordingly, these terms are used herein for the sole purpose of distinguishing different spatial, temporal or other relationships between different recited elements. The phrase "one or more of the following" or similar phrases means that at least one, but there can be one, two, three, or more, of the recited items can be employed. The phrase "one or more of the following exemplary aspects" as used herein does not mean that the feature of the one or more following aspects is necessarily included in some but not necessarily all embodiments of the disclosure. The mere fact that subsequent claims depend on a previous claim, does not place any restrictions on the embodiments of the previous claim. The term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations.

[0115] While certain features of the embodiments of the disclosure have been illustrated and described, modifications, substitutions, changes, and equivalents can occur to those skilled in the art. Accordingly, it is intended that the claims be construed to embrace any such modifications, substitutions, changes, and equivalents.

Claims

1. A cleanliness monitor, comprising: a first vacuum chamber; a second vacuum chamber; a mass spectrometer having a line of sight to an interior space of the second vacuum chamber; a molecule collector configured to, during an aggregation period and while positioned in a first position within the first vacuum chamber, aggregate organic molecules present in the first vacuum chamber to provide aggregated organic molecules; a release unit configured to, during a release period and while the molecule collector is positioned in a second position within the second vacuum chamber, initiate release of at least a subset of the aggregated organic molecules toward the mass spectrometer to provide released organic molecules; a manipulator configured to move the molecule collector from the first position to the second position; and wherein the mass spectrometer is configured to monitor the interior space of the second vacuum chamber and generate a detection signal indicative of contents of the interior space of the second vacuum chamber; wherein a first subset of the detection signal is indicative of a presence of the released organic molecules; and an analyzer configured to determine, based on the detection signal, the cleanliness of at least one of (a) the first vacuum chamber and (b) a vacuum chamber under test fluidically coupled to the first vacuum chamber.

2. The cleanliness monitor of claim 1, wherein a volume of an interior space of the first vacuum chamber is greater than a volume of the interior space of the second vacuum chamber.

3. The cleanliness monitor of claim 1, wherein a volume of an interior space of the first vacuum chamber is at least ten times greater than a volume of the interior space of the second vacuum chamber.

4. The cleanliness monitor of claim 1, comprising a sealing unit configured to separate the first vacuum chamber from the second vacuum chamber when the molecule collector is located within the second vacuum chamber.

5. The cleanliness monitor of claim 1, wherein the manipulator is configured to separate the first vacuum chamber from the second vacuum chamber when the molecule collector is located within the second vacuum chamber.

6. The cleanliness monitor of claim 1, wherein the manipulator comprises: (a) a movement mechanism mechanically coupled between the molecule collector and an interior space of the first vacuum chamber; and (b) a bellows configured to isolate the movement mechanism from the interior space of the first vacuum chamber at least during movement between the first position and the second position.

7. The cleanliness monitor of claim 1, comprising a flow control unit configured to (i) influence propagation of the released organic molecules during the release period and (ii) compare a pressure within the interior space of the second vacuum chamber to a pressure within the interior space of the first vacuum chamber after an end of the release period.

8. The cleanliness monitor of claim 1, wherein the release unit comprises a flow control unit, the flow control unit comprising a turbomolecular pump and a valve; wherein the valve is configured to be closed during a monitoring period; wherein the valve is configured to fluidly couple the interior space of the second vacuum chamber to the turbomolecular pump during at least a portion of the release period.

9. The cleanliness monitor of claim 1, comprising an opening shared by the first vacuum chamber and the second vacuum chamber; wherein the manipulator is configured to move the molecule collector through the opening while moving the molecule collector from the first position to the second position.

10. The cleanliness monitor of any one of claims 1 to 9, wherein the release unit comprises a heating element, the heating element being thermally coupled to the molecule collector.

11. The cleanliness monitor of claim 1, wherein the accumulation period is longer than the release period.

12. A method for cleanliness determination, the method comprising: accumulating, by a molecule collector, organic molecules present in a first vacuum chamber to provide accumulated organic molecules when the molecule collector is at a first position within the first vacuum chamber; wherein the first vacuum chamber is fluidly coupled to a second vacuum chamber; moving the molecule collector from the first position to a second position within the second vacuum chamber; initiating, by a release unit and during a release period, a release of at least a subset of the accumulated organic molecules to provide released organic molecules; monitoring, by a mass spectrometer, an interior space of the second vacuum chamber; generating, by the mass spectrometer, a detection signal indicative of contents of the interior space of the second vacuum chamber; wherein a first subset of the detection signal is indicative of a presence of the released organic molecules; and determining, by an analyzer and based on the detection signal, a cleanliness of at least one of the first vacuum chamber and a vacuum chamber under test.

13. The method of claim 12, wherein a volume of an interior space of the first vacuum chamber is greater than a volume of the interior space of the second vacuum chamber.

14. An evaluation system, comprising: a vacuum chamber under test; an evaluation module configured to evaluate a target located in the vacuum chamber under test; and a cleanliness monitor configured to monitor a cleanliness of at least one of the vacuum chamber under test and a first vacuum chamber of the cleanliness monitor; wherein the cleanliness monitor further comprises: a second vacuum chamber; a mass spectrometer; a molecule collector configured to accumulate, during an accumulation period and when located at a first position within the first vacuum chamber, organic molecules present in the first vacuum chamber to provide accumulated organic molecules; a release unit configured to initiate, during a release period and when the molecule collector is located at a second position within the second vacuum chamber, a release of at least a subset of the accumulated organic molecules towards the mass spectrometer to provide released organic molecules; a manipulator configured to move the molecule collector from the first position to the second position; and wherein the mass spectrometer has a line of sight to an interior space of the second vacuum chamber; wherein the mass spectrometer is configured to monitor the interior space of the second vacuum chamber and generate a detection signal indicative of contents of the interior space of the second vacuum chamber; wherein a first subset of the detection signal is indicative of a presence of the released organic molecules; and an analyzer configured to determine, based on the detection signal, the cleanliness of at least one of (a) the first vacuum chamber and (b) the tested vacuum chamber fluidically coupled to the first vacuum chamber.

15. The evaluation system of claim 14, wherein a volume of an interior space of the first vacuum chamber is greater than a volume of the interior space of the second vacuum chamber.

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