Method, system, and non-transitory computer readable medium for reducing a temperature difference between a sample and a chuck of an electron beam tool

Abstract

A method, non-transitory computer-readable medium, and system for reducing the temperature difference between a sample and a chuck of an electron beam tool. The method may include: determining a target temperature for a sample located at a loading port of the electron beam tool; setting the temperature of the sample at the loading port to the target temperature; moving the sample from the loading port to a chuck located within a vacuum chamber, the chuck being one of multiple samples; and positioning the sample on the chuck, wherein when the sample is positioned on the chuck, the temperature of the sample is substantially equal to the temperature of the chuck.

Description

[Technical Field]

[0001] This application claims priority to U.S. Application No. 16 / 995,058, filed August 17, 2020. The disclosure of that application is incorporated herein by reference in its entirety for all purposes.

[0002] This invention relates to reducing the temperature difference between the sample and the suction cup of the electron beam tool. [Previous Technology]

[0003] A scanning electron microscope is a high-resolution tool used to evaluate samples such as semiconductor wafers.

[0004] There are different types of scanning electron microscopes, including inspection scanning electron microscopes for examining suspected defects and critical size scanning electron microscopes for measuring the critical size of the microstructure of a sample.

[0005] In each scanning electron microscope, the sample is evaluated while it is positioned within the vacuum chamber of the scanning electron microscope.

[0006] The sample is supported by a suction cup. The suction cup is moved by a mechanical stage. The mechanical stage includes an engine and other components that can be heated during movement, thereby heating the suction cup.

[0007] Scanning electron microscopes should exhibit nanometer-level resolution. This nanometer-level resolution is achieved by scanning a sample area with an electron beam having an extremely small cross-section. Multiple areas of the sample can be scanned, typically one area after another.

[0008] The sample region is expected to include nanoscale features of interest. For example, the nanoscale features of interest may suffer from suspected defects. Alternatively or concurrently, the nanoscale features of interest may be features that are to be measured.

[0009] Before scanning the area, the mechanical stage can move the sample so that the area is within the field of view of the electron beam.

[0010] The electron beam should be positioned very precisely in order to scan nanoscale features of interest.

[0011] Due to the heating of the suction cup, there may be a significant temperature difference between the suction cup and the sample, which may cause the sample to deform slightly when it is positioned on the suction cup.

[0012] Deformation of the sample may introduce intolerable positional errors.

[0013] There is an increasing need to effectively reduce the significant temperature difference between the suction cup and the sample. [Summary of the Invention]

[0014] Methods for reducing the temperature difference between the suction cup and the sample, non-transitory computer-readable media, and detection systems may be provided.

Implementation Method

[0015] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present disclosure.

[0016] However, those skilled in the art will understand that this embodiment of the present disclosure can be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been detailed so as not to obscure this embodiment of the present disclosure.

[0017] The subject matter considered as embodiments of this disclosure is particularly pointed out and clearly claimed in the concluding section of this specification. However, embodiments of the organization and operation methods of this disclosure, as well as the objects, features, and advantages thereof, can be best understood by referring to the following detailed description when interpreted in conjunction with the accompanying drawings.

[0018] It should be understood that, for the purposes of simplicity and clarity of illustration, the elements shown in the accompanying drawings are not necessarily drawn to scale. For example, for clarity, the dimensions of some elements may be enlarged relative to other elements. Furthermore, reference numerals may be repeated between drawings where deemed appropriate to indicate corresponding or similar elements.

[0019] Because the embodiments shown in this disclosure can be implemented in most cases using electronic components and circuits known to those skilled in the art, the details will not be explained to a greater extent than that shown above as necessary in order to understand and appreciate the underlying concepts of this disclosure and in order not to obscure or distract from the teachings of this disclosure.

[0020] Any reference to the methods in this specification should be modified as necessary to apply to systems capable of performing the methods and should be modified as necessary to apply to non-transient computer-readable media storing instructions for performing the methods.

[0021] Any reference to the system in this specification should be modified as necessary to apply to methods that can be performed by said system and should be modified as necessary to apply to non-transitory computer-readable media that store instructions to be performed by said system.

[0022] Any reference in this specification to non-transitory computer-readable media should be adapted as necessary to the methods that may be applied when executing instructions stored in the computer-readable media, and should be adapted as necessary to a system configured to execute instructions stored in the computer-readable media.

[0023] The term "and / or" means additionally or alternatively.

[0024] The term "electron beam tool" refers to a tool that can generate one or more electron beams and scan a sample (or a region of the sample) with one or more electron beams. A scanning electron microscope is a non-limiting example of an electron beam tool.

[0025] Figure 1 illustrates a method 100 for reducing the temperature difference between the sample and the suction cup of the electron beam tool.

[0026] Method 100 may begin with step 110, wherein the target temperature of the sample located at the loading port of the electron beam tool is determined.

[0027] The phrase "sample located at the loading port" may include a sample located within the loading port, a sample supported by the loading port, a sample positioned on the loading port, a sample in a sample holder located within the loading port, a sample in a sample holder supported by the loading port, a sample in a sample holder positioned on the loading port, etc.

[0028] Step 110 may include step 112 of monitoring the temperature of the suction cup.

[0029] The temperature of the suction cup can change over time. On one hand, the movement of the mechanical stage can heat the suction cup. On the other hand, the temperature of the suction cup can decrease between two movements.

[0030] Monitoring should track temperature changes or at least the temperature during a relevant time window. The relevant time window can be before each sample is fed into the suction cup.

[0031] Monitoring may include measuring the temperature at one or more locations of the suction cup. Monitoring may include measuring the temperature at one or more locations thermally coupled to the suction cup or at any location having a known temperature relationship with the suction cup. Temperature measurements may be performed in a continuous or discontinuous manner, etc.

[0032] Temperature can be monitored, for example, before one or more samples are sent to the suction cup. Monitoring can occur multiple times before the sample is sent to the suction cup, such that the temperature of the sample can be set to the target temperature before the sample is sent.

[0033] The temperature of the suction cup can be estimated without monitoring the temperature. For example, the estimation of the suction cup temperature can be based on an analogy to the temperature or on any other estimate of the expected temperature change of the suction cup attributable to movement.

[0034] Step 110 may also include step 116. Step 112 may be followed by step 116, in which the target temperature is determined based on the result of step 112.

[0035] Step 116 can also respond to changes in sample temperature during the movement of the sample from the loading port to the suction cup. Temperature changes can be monitored, estimated, or calculated in any other way. The sample temperature is expected to decrease during the transfer of the sample from the sample holder to the suction cup.

[0036] Step 110 may also include step 114, wherein the temperature change of the sample is monitored during the movement of the sample from the loading port to the suction cup. This may include providing temperature measurements from different locations along the sample path.

[0037] When step 114 is executed, step 116 also responds to the result of step 114.

[0038] Step 110 can be followed by step 120, in which the temperature of the sample located at the loading port is set to the target temperature.

[0039] Setting the temperature of multiple samples (when the samples are in the loading port) prevents bottlenecks or any delays caused by setting the sample temperature only when the sample is moved to the wafer chamber.

[0040] By eliminating the delay in continuously feeding single samples into the suction cup, step 120 increases the system's output.

[0041] Step 120 may include flowing a gas with a controlled temperature toward the sample in the sample holder.

[0042] When positioned at the loading port, the sample can be located within a sample holder. The sample holder can be a box, a front-opening standard chamber (FOUP), etc.

[0043] Step 120 may include supplying gas at a controlled temperature to one or more gas distributors of the sample holder. The gas distributor may include a gas conduit and inlet and multiple outlets located at different heights and / or at different locations along the width of the gas distributor. The inlet may be selectively closed by the value of any other airflow control element.

[0044] Step 120 may include supplying gas with a controlled temperature to one or more gas dispensers located outside the sample holder, such as those located in the sample transfer unit.

[0045] Step 120 may be followed by step 130, in which the sample (from multiple samples) is moved from the loading port to the suction cup. The suction cup is located inside the vacuum chamber. The sample is taken from the sample holder.

[0046] The movement of the sample may include (a) moving the sample to the loading lock (e.g., by means of an automated material handling system, such as a robot arm of a sample transfer unit), and (b) moving the sample from the loading lock to the vacuum chamber.

[0047] Step 130 can be followed by step 140, wherein the sample is positioned on the suction cup, and when positioned on the suction cup, the temperature of the sample is substantially equal to the temperature of the suction cup.

[0048] Step 140 may be followed by evaluating the sample during the evaluation period. The evaluation may include at least one of examining the sample, measuring the sample dimensions (such as critical dimensions), etc. The temperature of the suction cup may be monitored at at least some points during the evaluation period.

[0049] The temperature of the sample can be considered substantially equal to the temperature of the suction cup when the temperature difference between the sample temperature and the suction cup temperature is: (a) below a temperature threshold, for example, below 0.5 degrees Celsius; and additionally or alternatively, (b) a value that causes sample deformation below a sample deformation threshold (e.g., below 100 nanometers). Values ​​other than 0.5 degrees Celsius and 100 nanometers can be provided.

[0050] Steps 110, 120, 130, and 140 can be repeated multiple times. During each repetition, one or more samples are moved from the loading port to the suction cup. For example, if each repetition of steps 110, 120, 130, and 140 is associated with a single sample, then multiple repetitions are performed on multiple samples in the loading port.

[0051] After the evaluation of the sample is completed, the sample can be returned to the loading port.

[0052] A system may be provided for reducing the temperature difference between the sample and the chuck of the electron beam tool. The system may be an electron beam tool, the system may be included in the electron beam tool, or the system may have at least one unit added to the electron beam tool.

[0053] Figures 2 and 3 show examples of the electron beam tool 10.

[0054] In Figures 2 and 3, it is assumed that the system is included in the electron beam tool 10.

[0055] The electron beam tool 10 includes a loading port 12, a sample transfer unit 13, a loading lock 14, a moving mechanism that may include an automated material handling system 18, a suction cup 20, a mechanical stage 22, a vacuum chamber 24, an electron beam column 26, a controller 28, a processor 30, one or more temperature control units 32, one or more temperature sensors 34, and a monitor 36.

[0056] Samples 40(1) to 40(N) can be held in sample holder 42. N is an integer greater than one. A single sample is represented as 42(n), where n is in the range of 1 to N.

[0057] The sample holder 42 can be positioned at the loading port 12. The loading port 12, or sample holder 42, is connected to the sample transfer unit 13 via the door 13(1) of the sample transfer unit 13.

[0058] The door 13(1) can be closed to limit the internal space 13(2) of the sample transfer unit.

[0059] The sample rack 42 may include a housing, which may include a sample rack door 42(1) that can be positioned in front of the door 13(1).

[0060] The housing can provide a closed environment that can be exposed to the door 13(1) when the sample rack door 42(1) is opened.

[0061] A sample can be taken from the sample rack 42 or returned to the sample rack 42 via the door 13 (1) and the sample rack door 42 (1).

[0062] The sample temperature in the sample holder 42 can be set by setting the temperature in at least a portion of the sample transfer unit 13, in particular by guiding a gas with a controlled temperature through the door 13 (1) and then through the sample holder door 42 (1).

[0063] In Figure 2, one or more temperature control units 32 are positioned outside the sample holder 42 and inside the sample transfer unit 13, facing the door 13 (1).

[0064] Figure 2 also shows a side view of a temperature control unit, which includes a gas distributor, such as a tube 33 having a plurality of holes 33(1) to 33(K) that can be positioned to face samples 40(1) to 42(N). N can be equal to K. K can be less than N. For example, K can be half of N. K can be greater than N. Gas can be fed to the tube 33 by an external gas supply unit 35. The holes can form columns, can be used in a two-dimensional array, can be located at different heights and positioned at different width coordinates of the tube.

[0065] The automatic material handling system 18 can be configured to move the sample 40(n) from the sample holder 42 to the loading lock 14.

[0066] Loading lock 14 is configured to receive a sample, introduce a desired vacuum level within loading lock 14, and subsequently expose sample 40(n) to vacuum chamber 24.

[0067] A robotic arm or other mechanical unit (not shown) can move the sample from the loading lock 14 to the suction cup 20. The suction cup 20 is supported by the mechanical stage 22, moved within the vacuum chamber by the mechanical stage 22, and heated by the mechanical stage 22.

[0068] In FIG2, one or more temperature sensors 34 are shown as a single temperature sensor thermally coupled to the suction cup 20 and configured to measure the temperature of the suction cup 20.

[0069] The temperature of the suction cup can be estimated based on measurements obtained from one or more sensors located at one or more locations.

[0070] It should be noted that one or more temperature sensors 34 can measure the temperature of at least one of the mechanical stage 22 of loading port 12, loading lock 14, sample 40(n), sample holder 42, etc.

[0071] Temperature measurements from any temperature sensor can be fed to monitor 36. Monitor 36 can determine the temperature of the suction cup and send temperature information about the suction cup temperature to controller 28.

[0072] Based on temperature information, the controller 28 can determine the target temperature of the sample in the sample holder.

[0073] It should be noted that the controller 28 and the monitor 36 may be combined, or the temperature monitoring task may be performed at least partially by the controller 28.

[0074] The temperature is set such that the temperature of the suture (when the sample 40(n) is positioned on the suture) is substantially equal to the temperature of the sample 40(n) (when positioned on the suture). The temperature of the suture should be substantially equal to the target temperature of the sample minus the temperature change introduced by the movement of the sample 40(n) from the sample holder to the suture.

[0075] The suction cup can be hotter than the sample in the sample holder (when no temperature setting is applied within the sample holder 42). Temperature setting typically involves heating the sample in the sample holder.

[0076] Nevertheless, the temperature of the suction cup changes and may decrease during certain time windows, typically after the mechanical stage stops moving. In such cases, the target temperature of the sample can be lower.

[0077] In Figure 3, one or more temperature control units 32 are included in the sample holder.

[0078] Figure 3 also shows a gas distributor, such as tube 33, which has a plurality of holes 33(1) to 33(K) included in the sample holder. The tube can be fed by an external gas supply unit 35 located outside the sample holder.

[0079] In FIG3, one or more temperature sensors 34 are shown as including (a) a temperature sensor that is thermally coupled to the suction cup 20 and configured to measure the temperature of the suction cup 20, and (b) another temperature sensor that is configured to sense the temperature of the sample in the sample holder.

[0080] In the foregoing description, embodiments of the present disclosure have been described with reference to specific examples of embodiments thereof. However, it will be apparent that various modifications and variations may be made therein without departing from the broad spirit and scope of the embodiments of the present disclosure as set forth in the appended claims.

[0081] Furthermore, the terms "in front of," "behind," "top," "bottom," "above," "below," etc. (if any) used in the specification and claims are for descriptive purposes and are not necessarily used to describe permanent relative positions. It should be understood that, where appropriate, such terms may be used interchangeably so that embodiments of this disclosure described herein can, for example, operate in other orientations different from those shown or otherwise described herein.

[0082] The connections discussed herein can be any type of connection suitable for transmitting signals from or to a corresponding node, unit, or device, for example, via an intermediate means. Therefore, unless otherwise implied or stated, a connection can be, for example, a direct connection or an indirect connection. Connections can be shown or described with respect to a single connection, multiple connections, unidirectional connections, or bidirectional connections. However, different embodiments can vary the implementation of the connection. For example, separate unidirectional connections can be used instead of bidirectional connections, and vice versa. Furthermore, multiple connections can be replaced by a single connection that transmits multiple signals in series or in a time-division multiplexing manner. Similarly, a single connection carrying multiple signals can be separated into multiple different connections carrying subsets of those signals. Therefore, there are multiple options for transmitting signals.

[0083] Any arrangement of components to achieve the same function is effectively "associated" to achieve the desired function. Therefore, regardless of the construction or intermediate components, any two components combined herein to achieve a specific function can be considered as "associated" with each other to achieve the desired function. Similarly, any two components associated in this way can also be considered as "operably connected" or "operably coupled" to each other to achieve the desired function.

[0084] Furthermore, those skilled in the art will recognize that the boundaries between the operations described above are merely illustrative. Multiple operations may be combined into a single operation, a single operation may be assigned to additional operations, and operations may be performed with at least partial overlap in time. Additionally, alternative embodiments may include multiple instances of a particular operation, and the order of operations may be varied in various other embodiments.

[0085] Furthermore, for example, in one embodiment, the illustrated example may be implemented in the form of a circuit system located on a single integrated circuit or within the same device. Alternatively, the example may be implemented in the form of any number of separate integrated circuits or separate devices interconnected to each other in a suitable manner.

[0086] However, other modifications, variations, and substitutions are also possible. Therefore, the specification and drawings should be viewed in an illustrative rather than restrictive sense.

[0087] In the claims, any reference numerals placed between parentheses should not be construed as limiting the scope of the claim. The word "comprising" does not exclude the presence of elements or steps other than those listed in the claims. Furthermore, as used herein, the terms "a" or "an" are defined as one or more. Moreover, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an," introductory phrases such as "at least one" and "one or more" used in the claims should not be construed as implying that the introduction of another claim element by the indefinite article "a" or "an" limits any particular claim containing such claim elements incorporated into embodiments of this disclosure to contain only one such element. This also applies to the use of definite articles. Unless otherwise stated, terms such as "first" and "second" are used to arbitrarily distinguish elements described by such terms. Therefore, these terms are not necessarily intended to indicate temporal or other priority of such elements. The fact that certain measures are recorded in different requests does not indicate that combinations of these measures cannot be used advantageously.

[0088] Although certain features of embodiments of this disclosure have been shown and described herein, many modifications, substitutions, variations, and equivalents will now come to the attention of those skilled in the art. Therefore, it should be understood that the appended claims are intended to cover all such modifications and variations that fall within the true spirit of the embodiments of this disclosure. [Simplified Explanation of the Diagram]

[0090] The subject matter considered as embodiments of this disclosure is particularly pointed out and clearly claimed in the concluding section of this specification. However, embodiments of the organization and operation methods of this disclosure, as well as the objects, features, and advantages thereof, can be best understood by referring to the following detailed description when interpreted in conjunction with the accompanying drawings, wherein:

[0091] Figure 1 shows an example of the method;

[0092] Figure 2 shows an example of an electron beam system; and

[0093] Figure 3 shows an example of an electron beam system. [Biomaterial Storage]

[0094] Domestic storage information (please note in order of storage institution, date, and number): None. International storage information (please note in order of storage country, institution, date, and number): None.

Claims

1. A method for reducing a temperature difference between a sample and a suction cup of an electron beam tool, the method comprising the steps of: using a first temperature sensor to monitor a temperature of the suction cup, the first temperature sensor being thermally coupled to the suction cup and configured to sense the temperature of the suction cup; determining a target temperature of the sample located in a sample holder at a loading port of the electron beam tool; setting a temperature of the sample located at the loading port to the target temperature by infusing a gas having a controlled temperature into the sample holder; using a second temperature sensor to monitor the temperature of the sample, the second temperature sensor being configured to sense the temperature of the sample in the sample holder; moving the sample from the loading port to the suction cup, the suction cup being located within a vacuum chamber; and positioning the sample on the suction cup, wherein when the sample is positioned on the suction cup, the temperature of the sample is substantially equal to a temperature of the suction cup.

2. The method of claim 1, wherein the target temperature is determined based on the temperature of the suction cup and based on a temperature change of the sample during a movement of the sample from the loading port to the suction cup.

3. The method of claim 2, wherein moving the sample from the loading port to the suction cup includes the step of: monitoring the temperature change of the sample during the movement of the sample from the loading port to the suction cup.

4. The method of claim 1, wherein the sample is a first sample, and wherein the method further comprises the steps of: moving a second sample from the loading port to the suction cup; and positioning the second sample on the suction cup, wherein when the second sample is positioned on the suction cup, a temperature of the second sample is substantially equal to a temperature of the suction cup.

5. The method of claim 4, wherein moving the second sample from the loading port to the suction cup includes the step of determining the target temperature after moving the first sample and before moving the second sample.

6. The method of claim 1, wherein when the sample is positioned at the loading port, the sample is located within the sample holder, and wherein setting the temperature includes the step of: supplying the gas having the controlled temperature to one or more gas dispensers of the sample holder.

7. The method as described in claim 6, wherein the one or more gas distributors include an inlet and multiple outlets located at different heights.

8. The method of claim 1, wherein when the sample is positioned at the loading port, the sample is located within the sample holder, and wherein setting the temperature includes the step of supplying the gas having the controlled temperature to one or more gas dispensers positioned outside the sample holder.

9. A system for reducing a temperature difference between a sample and a suction cup of an electron beam tool, the system comprising: A temperature sensor thermally coupled to the suction cup and configured to sense a temperature of the suction cup; A controller configured to determine a target temperature of the sample located at a loading port of the electron beam tool; one or more temperature control units configured to set a temperature of the sample located at the loading port to the target temperature by flowing gas having a controlled temperature into a sample holder; a moving mechanism configured to: move the sample from the loading port to the suction cup located in a vacuum chamber; and position the sample on the suction cup, wherein when the sample is positioned on the suction cup, the temperature of the sample is substantially equal to a temperature of the suction cup.

10. The system as claimed in claim 9 further includes a monitor configured to monitor the temperature of the suction cup.

11. The system of claim 9, wherein the controller is configured to determine the target temperature based on the temperature of the suction cup and based on a temperature change of the sample during a movement of the sample from the loading port to the suction cup.

12. The system of claim 9, wherein when the sample is positioned at the loading port, the sample is located within the sample holder, and wherein the one or more temperature control units include one or more gas distributors of the sample holder.

13. The system of claim 9, wherein when the sample is positioned at the loading port, the sample is located within the sample holder, and wherein the one or more temperature control units include one or more gas distributors located outside the sample holder.

14. A non-transitory computer-readable medium storing instructions for: using a first temperature sensor to monitor a temperature of a suction cup, the first temperature sensor being thermally coupled to the suction cup and configured to sense the temperature of the suction cup; using a second temperature sensor to determine a target temperature of a sample located in a sample holder at a loading port of an electron beam tool, the second temperature sensor being configured to sense the temperature of the sample in the sample holder; setting a temperature of the sample located at the loading port to the target temperature by infusing a gas having a controlled temperature into a sample holder; moving the sample from the loading port to a suction cup located within a vacuum chamber; and positioning the sample on the suction cup, wherein when the sample is positioned on the suction cup, a temperature of the sample is substantially equal to a temperature of the suction cup.

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