Method and device for maintaining constant temperature of objective lens in charged particle beam system

Abstract

The present application relates to the technical field of electromagnetic coils, and discloses a method and device for maintaining a constant temperature of an objective lens in a charged particle beam system. The method comprises: determining the maximum ampere-turns required for the coil of the objective lens to generate a magnetic field and determining the total heating power of the objective lens according to the maximum ampere-turns; obtaining the number of coil turns and the resistance value corresponding to each coil of the coarse adjustment coil, the fine adjustment coil, and the power compensation coil; and coordinating the current values ​​corresponding to each coil of the coarse adjustment coil, the fine adjustment coil, and the power compensation coil according to the target ampere-turns, the total heating power, the number of coil turns and the resistance value corresponding to each coil, so as to maintain a constant temperature of the objective lens. By using the scheme of the present application, the power can be kept constant under different working conditions to maintain a constant temperature of the objective lens.

Description

Technical Field

[0001] The present application generally relates to the field of electromagnetic coil technology. More specifically, the present application relates to a method for maintaining a constant temperature of an objective lens in a charged particle beam system, a constant temperature objective lens, a charged particle beam system, an apparatus, and a computer-readable storage medium. Background Art

[0002] In a charged particle beam system, the objective lens coil will generate a lot of heat under the stimulation of electric current. When the operating conditions are different, the current value applied to the coil will also be different, which will cause the total power value of the objective lens coil to be in a changing state, and then the coil will generate different heat. The thermal instability of the entire system will cause the device parameters of the objective lens to drift in temperature. Temperature drift makes it impossible to control the performance of the device in a stable state, which will affect the beam spot size and resolution of the charged particle beam, thereby affecting the stability and accuracy of the entire charged particle beam system. For example, the temperature drift caused by the heating of the objective lens in a scanning electron microscope will affect the resolution of the final generated image.

[0003] At present, cooling is usually achieved by adding cooling pipes to the heating parts such as the objective lens coil or by winding the heat exchange pipe and passing a flowing heat exchange medium. This type of cooling method can effectively curb the temperature rise of the system caused by the heating of the objective lens coil. However, in the charged particle beam system, the power of the objective lens coil is not constant. When the coil power changes, the existing cooling method cannot ensure the constant temperature after heat exchange, and the existing cooling method has a certain hysteresis.

[0004] In view of this, there is an urgent need to provide a solution for maintaining a constant temperature of an objective lens in a charged particle beam system, so as to maintain a constant power under different working conditions and thus maintain a constant temperature of the objective lens. Summary of the invention

[0005] In order to at least solve one or more of the technical problems mentioned above, the present application proposes a solution for maintaining a constant temperature of an objective lens in a charged particle beam system in multiple aspects.

[0006] In a first aspect, the present application provides a method for maintaining a constant temperature of an objective lens in a charged particle beam system, wherein the objective lens comprises a coarse adjustment coil, a fine adjustment coil and a power compensation coil, wherein the power compensation coil has an opposite magnetic field to the coarse adjustment coil and the fine adjustment coil, and the method comprises: determining a maximum ampere-turn required for the coil of the objective lens to generate a magnetic field and determining a total heating power of the objective lens based on the maximum ampere-turn; obtaining the number of coil turns and the resistance value corresponding to each coil of the coarse adjustment coil, the fine adjustment coil and the power compensation coil; and coordinating the current value corresponding to each coil of the coarse adjustment coil, the fine adjustment coil and the power compensation coil based on the target ampere-turn, the total heating power, the number of coil turns and the resistance value corresponding to each coil, so as to maintain a constant temperature of the objective lens.

[0007] In some embodiments, the power compensation coil and the coarse adjustment coil and the fine adjustment coil have opposite magnetic fields by: setting the winding direction of the power compensation coil opposite to the winding direction of the coarse adjustment coil and the fine adjustment coil; or the direction of the current passed through the power compensation coil opposite to the direction of the current passed through the coarse adjustment coil and the fine adjustment coil.

[0008] In other embodiments, the current value corresponding to each coil of the coarse adjustment coil, the fine adjustment coil and the power compensation coil is set with a maximum excitation value.

[0009] In some other embodiments, the total heating power of the objective lens is determined by the following operations: obtaining the maximum excitation value of the current value corresponding to each of the coarse adjustment coil and the fine adjustment coil according to the maximum ampere-turns; and calculating the total heating power of the objective lens based on the maximum excitation value of the corresponding current value and the resistance value corresponding to each of the coarse adjustment coil and the fine adjustment coil.

[0010] In some other embodiments, coordinating the current values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil according to the target ampere-turns, the total heat generation power, the coil turns and the resistance value corresponding to each coil includes: coordinating the current values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil according to the following formula:

[0011]

[0012] in, represents the target ampere-turns, represents the total heating power of the objective lens, , and respectively represent the current values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil, , and Respectively represent the number of coil turns corresponding to each coil of the coarse adjustment coil, the fine adjustment coil and the power compensation coil; , and Respectively represent the resistance values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil.

[0013] In some other embodiments, the resistance values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil are calculated based on the coil lengths and wire cross-sectional areas corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil.

[0014] In a second aspect, the present application provides a constant temperature objective lens, comprising at least: a coarse adjustment coil, a fine adjustment coil and a power compensation coil, wherein the power compensation coil has an opposite magnetic field to the coarse adjustment coil and the fine adjustment coil, wherein the coarse adjustment coil, the fine adjustment coil and the power compensation coil cooperate under one or more embodiments of the aforementioned first aspect to keep the constant temperature objective lens at a constant temperature.

[0015] In a third aspect, the present application provides a charged particle beam system, comprising: the constant temperature objective lens described in the aforementioned second aspect.

[0016] In a fourth aspect, the present application provides a device for maintaining a constant temperature of an objective lens in a charged particle beam system, comprising: a processor; and a memory on which computer instructions for maintaining a constant temperature of an objective lens in the charged particle beam system are stored, and when the computer instructions are executed by the processor, the device implements one or more embodiments of the aforementioned first aspect.

[0017] In a fifth aspect, the present application provides a computer-readable storage medium having stored thereon computer program instructions for maintaining a constant temperature of an objective lens in a charged particle beam system, wherein when the computer program instructions are executed by one or more processors, one or more embodiments of the aforementioned first aspect are implemented.

[0018] Through the scheme for maintaining the constant temperature of the objective lens in the charged particle beam system provided above, the embodiment of the present application adds a power compensation coil having an opposite magnetic field to the coarse adjustment coil and the fine adjustment coil, and coordinates the current values ​​corresponding to the coarse adjustment coil, the fine adjustment coil, and the power compensation coil at different target ampere-turns according to the total heating power determined by the maximum ampere-turns. That is, through the coordinated action of the coarse adjustment coil, the fine adjustment coil, and the power compensation coil, the current values ​​of the three coils are coordinated to achieve constant power of the objective lens coil, thereby achieving constant temperature of the objective lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] By reading the detailed description below with reference to the accompanying drawings, the above and other purposes, features and advantages of the exemplary embodiments of the present application will become easy to understand. In the accompanying drawings, several embodiments of the present application are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0020] Figure 1 is an exemplary flow chart showing a method for maintaining a constant temperature of an objective lens in a charged particle beam system according to an embodiment of the present application;

[0021] Figure 2 is an exemplary schematic diagram showing a constant temperature objective lens according to an embodiment of the present application;

[0022] Figure 3 is an exemplary structural block diagram showing a charged particle beam system according to an embodiment of the present application;

[0023] Figure 4 Detailed description is a block diagram showing an exemplary structure of a device for maintaining a constant temperature of an objective lens in a charged particle beam system according to an embodiment of the present application. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0025] It should be understood that the terms "include" and "comprising" used in the specification of the present application indicate the presence of described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0026] It should also be understood that the terms used in this specification of the application are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in the specification of the application, the singular forms of "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise. It should also be further understood that the term "and / or" used in the specification of the application refers to any combination of one or more of the associated listed items and all possible combinations, including these combinations.

[0027] As used in this specification, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if the described condition or event is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce the described condition or event is detected" or "in response to detecting the described condition or event", depending on the context.

[0028] Figure 1 FIG. 1 is an exemplary flow chart showing a method 100 for maintaining a constant temperature of an objective lens in a charged particle beam system according to an embodiment of the present application. Figure 1 As shown in, the method 100 includes: step S101: determining the maximum ampere-turns required for the coil of the objective lens to generate a magnetic field and determining the total heating power of the objective lens according to the maximum ampere-turns; step S102: obtaining the number of coil turns and the resistance value corresponding to each coil of the coarse adjustment coil, the fine adjustment coil and the power compensation coil; step S103: coordinating the current value corresponding to each coil of the coarse adjustment coil, the fine adjustment coil and the power compensation coil according to the target ampere-turns, the total heating power, the number of coil turns and the resistance value corresponding to each coil, so as to keep the objective lens at a constant temperature.

[0029] In some embodiments, the objective lens includes a coarse adjustment coil, a fine adjustment coil, and a power compensation coil. In some implementation scenarios, the coarse adjustment coil, the fine adjustment coil, and the power compensation coil can be wound by an objective lens wire frame. The power compensation coil has an opposite magnetic field to the coarse adjustment coil and the fine adjustment coil.

[0030] In some implementation scenarios, the power compensation coil and the coarse adjustment coil and the fine adjustment coil may have opposite magnetic fields by: setting the winding direction of the power compensation coil to be opposite to the winding direction of the coarse adjustment coil and the fine adjustment coil; or the current direction passed into the power compensation coil to be opposite to the current direction of the coarse adjustment coil and the fine adjustment coil. That is, the power compensation coil and the coarse adjustment coil and the fine adjustment coil may have opposite magnetic fields by setting the winding direction of the power compensation coil or the current direction passed into the power compensation coil to be opposite to the coarse adjustment coil and the fine adjustment coil.

[0031] First, at step S101, the maximum ampere-turns required for the coil of the objective lens to generate a magnetic field are determined, and the total heating power of the objective lens is determined based on the maximum ampere-turns. That is, it is necessary to determine the maximum usable power of the coil, and use this power as a constant value of the objective lens coil power. In some embodiments, the maximum excitation value of the current value corresponding to each of the coarse adjustment coil and the fine adjustment coil can be obtained based on the maximum ampere-turns; and the total heating power of the objective lens can be calculated based on the maximum excitation value of the corresponding current value and the resistance value corresponding to each of the coarse adjustment coil and the fine adjustment coil. In other embodiments, the current value corresponding to each coil of the coarse adjustment coil, the fine adjustment coil and the power compensation coil is set with a maximum excitation value. Preferably, the maximum excitation value is 1A.

[0032] Next, at step S102, the number of coil turns and resistance values ​​corresponding to each of the coarse adjustment coil, the fine adjustment coil, and the power compensation coil are obtained. In some embodiments, the resistance values ​​corresponding to each of the coarse adjustment coil, the fine adjustment coil, and the power compensation coil are calculated based on the coil lengths and wire cross-sectional areas corresponding to each of the coarse adjustment coil, the fine adjustment coil, and the power compensation coil. Among them, after the number of coil turns of the three coils is determined, the winding length of each coil can be calculated based on the number of coil turns and the circumference of each turn. In addition, based on the winding wire used for each coil, the wire diameter can be obtained, and then the wire cross-sectional area can be obtained based on the wire diameter. Thus, the resistance value R corresponding to each of the coarse adjustment coil, the fine adjustment coil, and the power compensation coil can be calculated based on R=ρ×L / S, where ρ represents the resistivity, L represents the coil length, and S represents the wire cross-sectional area.

[0033] Based on the maximum ampere-turns, the current values ​​corresponding to the coarse adjustment coil and the fine adjustment coil are the maximum excitation values ​​(for example, 1A), and the resistance values ​​corresponding to the coarse adjustment coil and the fine adjustment coil are obtained. Calculate the total heating power C of the objective lens. In this formula, , They represent the maximum excitation value 1A of the current value corresponding to the coarse adjustment coil and the fine adjustment coil respectively. , They respectively represent the resistance values ​​corresponding to the coarse adjustment coil and the fine adjustment coil.

[0034] It can be understood that the coarse adjustment coil and the fine adjustment coil of the present application are both used to adjust the focus, the coarse adjustment changes are larger, and the fine adjustment changes are smaller. When the objective lens coil is in the use state of the maximum ampere-turns, the power compensation coil of the objective lens is not excited, and only the coarse adjustment coil and the fine adjustment coil are in the working state. When the target ampere-turns of the objective lens coil are lower than the maximum ampere-turns, the power compensation coil is excited, and it starts to work in coordination with the coarse adjustment and fine adjustment coils. In this scenario, since the winding direction of the power compensation coil is opposite to the direction of the coarse adjustment and fine adjustment coils, the power compensation coil will generate a magnetic field in the opposite direction of the coarse adjustment and fine adjustment coils after being excited, thereby generating a part of the opposite magnetic field to offset a part of the magnetic field generated by the coarse adjustment and fine adjustment coils, so that the total ampere-turns (i.e., the current ampere multiplied by the number of coil turns) will be reduced, and the total magnetic field meets the detection requirements. At this time, the heating power of the objective lens coil is still provided by the coarse adjustment coil, the fine adjustment coil and the power compensation coil. Based on this, with the coordinated work of the coarse adjustment coil, fine adjustment coil and power compensation coil, it is possible to reduce the total ampere-turns of the objective lens coil, while meeting the turns requirement of the objective lens coil and keeping the total heating power of the objective lens coil in a constant state.

[0035] Specifically, at step S103, the current values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil are coordinated according to the target ampere-turns, the total heating power, the coil turns and the resistance value corresponding to each coil to maintain a constant temperature of the objective lens.

[0036] In some embodiments, the current values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil are coordinated by the following formula:

[0037]

[0038] in, C Indicates the total heating power, represents the target ampere-turns, , and They represent the current values ​​corresponding to the coarse adjustment coil, fine adjustment coil and power compensation coil respectively. , and They represent the number of coil turns corresponding to the coarse adjustment coil, fine adjustment coil and power compensation coil, respectively. , and They represent the resistance values ​​of the coarse adjustment coil, fine adjustment coil and power compensation coil respectively. That is, at different target ampere-turns AT Under this condition, the current values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil are calculated by combining the above formula (1) and formula (2) so as to make the total heating power C of the objective lens constant, thereby maintaining a constant temperature of the objective lens.

[0039] In combination with the above description, it can be known that the embodiment of the present application adds a power compensation coil with an opposite magnetic field to the coarse adjustment coil and the fine adjustment coil, determines the total heating power of the objective lens according to the maximum ampere-turns, and coordinates the current values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil according to the total heating power, the target ampere-turns and the winding conditions of each coil (such as the number of coil turns and the resistance value), so as to achieve constant power of the objective lens coil under different operating conditions, so as to keep the objective lens at a constant temperature. Based on this, the temperature drift problem caused by the change of the temperature of the objective lens can be reduced, thereby effectively improving the accuracy of the charged particle beam system.

[0040] Figure 2 2 is an exemplary schematic diagram showing a constant temperature objective lens 200 according to an embodiment of the present application. Figure 2As shown in , the constant temperature objective lens 200 may include a coarse adjustment coil 201, a fine adjustment coil 202, and a power compensation coil 203. The coarse adjustment coil 201, the fine adjustment coil 202, and the power compensation coil 203 are wound via an objective lens wire frame 204, and the power compensation coil 203 has an opposite magnetic field to the coarse adjustment coil 201 and the fine adjustment coil 202. In some embodiments, the coarse adjustment coil 201, the fine adjustment coil 202, and the power compensation coil 203 are all made of copper, and the models (such as wire diameters) are the same. In the implementation scenario, the coarse adjustment coil, the fine adjustment coil, and the power compensation coil work together under the above method of the embodiment of the present application to keep the constant temperature objective lens constant.

[0041] The figure shows that the winding direction of the power compensation coil 203 is opposite to the winding direction of the coarse adjustment coil 201 and the fine adjustment coil 202. For example, the power compensation coil 203 is wound in the instantaneous clockwise direction (as shown by arrow A in the figure), and the coarse adjustment coil 201 and the fine adjustment coil 202 are wound in the counterclockwise direction (as shown by arrow B in the figure). As known from the foregoing, when the power compensation coil 203 is excited, a magnetic field opposite to the coarse adjustment coil and the fine adjustment coil is generated to cooperate with the coarse adjustment coil and the fine adjustment coil.

[0042] In other embodiments, the winding direction of the power compensation coil 203 may be the same as that of the coarse adjustment coil 201 and the fine adjustment coil 202, and when the power compensation coil 203 is excited, a current opposite to that of the coarse adjustment coil 201 and the fine adjustment coil 202 may be passed. This may also enable the power compensation coil 203 to generate a magnetic field opposite to that of the coarse adjustment coil and the fine adjustment coil after being excited, so as to work in coordination with the coarse adjustment coil and the fine adjustment coil. Specifically, the total heating power may be determined based on the maximum ampere-turns, and then the current values ​​of the coarse adjustment coil, the fine adjustment coil and the power compensation coil may be coordinated by combining the above formula (1) and formula (2) to maintain a constant temperature of the objective lens.

[0043] Figure 3 FIG. 3 is a block diagram showing an exemplary structure of a charged particle beam system 300 according to an embodiment of the present application. Figure 3 As shown in the figure, the charged particle beam system 300 may include at least the constant temperature objective lens 200 of the embodiment of the present application. It should be understood that what is shown in the figure is only exemplary. In addition to the constant temperature objective lens, the charged particle beam system 300 may also include conventional structures such as a particle beam source, a deflection device, etc., which are not described in detail in this application.

[0044] As can be seen from the foregoing, the constant temperature objective lens 200 may include a coarse adjustment coil, a fine adjustment coil and a power compensation coil, and the power compensation coil has an opposite magnetic field to the coarse adjustment coil and the fine adjustment coil. For more details about the constant temperature objective lens 200, please refer to the above Figure 2 The description made will not be repeated in this application.

[0045] It can be understood that when the charged particle beam system is working, the heat generated by the objective lens is basically caused by the Joule heat generated after the current is passed through the objective lens coil. After the current is passed through, the objective lens coil can be used as an electromagnetic lens to generate a magnetic field to focus the charged particle beam passing through. According to the different particle beam focusing requirements of the charged particle beam system, the current excitation passed through the objective lens coil will change, which will also cause the heat generated by the objective lens coil to fluctuate greatly. The power compensation coil in the objective lens coil of the embodiment of the present application is opposite to the winding direction of the coarse adjustment and fine adjustment coils or the current passed through is opposite, so that the power compensation coil generates a magnetic field opposite to the coarse adjustment and fine adjustment coils. Based on the above formula (1) and formula (2), by coordinating the current values ​​of the three coils of the coarse adjustment coil, the fine adjustment coil and the power compensation coil, the heat generated by the coil is kept constant under different ampere-turn requirements, so as to keep the objective lens constant temperature and improve the accuracy of the charged particle beam system.

[0046] The method for maintaining a constant temperature of an objective lens in a charged particle beam system according to an embodiment of the present application will be described below by taking the ampere-turns of an objective lens coil of 1000-2000 AT as an example.

[0047] According to the previous text, we first determine the maximum ampere-turns required for the objective lens coil to generate a magnetic field. Taking the ampere-turns of 1000-2000AT as an example, when the ampere-turns are 2000, it is the maximum ampere-turns required for the objective lens coil to generate a magnetic field, that is, the maximum power used. In this scenario, the current values ​​of the coarse adjustment coil and the fine adjustment coil are the largest. Considering that the subsequent objective lens is more flexible in actual use, the ratio of the number of turns of the coarse adjustment coil and the fine adjustment coil is designed as 9:1, and the maximum current excitation value of the coil is designed to be 1A. It can be obtained that the number of turns N0 of the coarse adjustment coil and the number of turns N1 of the fine adjustment coil are N0=1800 and N1=200 respectively. Next, the coil length can be determined according to the number of turns of each coil, and the winding length of each coil is calculated in combination with the circumference of each turn. In addition, the wire cross-sectional area can be obtained according to the winding wire used for each coil, and then the resistance value R0 of the coarse adjustment coil and the resistance value R1 of the fine adjustment coil are calculated by R=ρ×L / S to be R0=16.998Ω and R1=1.889Ω respectively.

[0048] That is to say, when the maximum effective ampere-turns is 2000 ampere-turns, the objective lens reaches the maximum load, the current values ​​corresponding to the coarse adjustment coil and the fine adjustment coil are both 1A, and the current value of the power compensation coil is 0A. In this scenario (that is, the effective scenario is the maximum load), through The total heating power C of the objective lens is obtained. For example, the total heating power C of the objective lens can be calculated to be 18.887W.

[0049] When the ampere-turns is 1000, it is the minimum operating condition. In this scenario, the power compensation coil has the maximum power. As an example, assume that the number of turns N2 of the power compensation coil is set to N2=600, and the wire used by the power compensation coil is the same as the wire used by the coarse adjustment coil and the fine adjustment coil. Similarly, the resistance value of the power compensation coil can be obtained as R2=5.6636Ω. In this scenario (i.e., the effective ampere-turns are low load), the current values ​​of the three coils, the coarse adjustment coil, the fine adjustment coil and the power compensation coil, are coordinated by combining the above formulas (1) and (2) to maintain the constant temperature of the objective lens.

[0050] Table 1 below shows the current values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil respectively after coordination using the solution of the embodiment of the present application under different ampere-turns.

[0051] Table 1 Current values ​​of each coil after coordination at different ampere-turns

[0052]

[0053] As shown in Table 1, through the solution of the embodiment of the present application, the corresponding current excitation values ​​of the three coils, namely the coarse adjustment coil, the fine adjustment coil and the power compensation coil, can be calculated under each ampere-turn requirement, so as to achieve constant power of the objective lens under different operating conditions, thereby achieving constant temperature of the objective lens. Based on this, the temperature drift caused by the change of the objective lens temperature can be reduced, thereby effectively improving the accuracy of the charged particle beam system.

[0054] Figure 4 4 is an exemplary structural block diagram showing a device 400 for maintaining a constant temperature of an objective lens in a charged particle beam system according to an embodiment of the present application. Figure 4 As shown in , the device 400 of the present application may include a processor 401 and a memory 402, wherein the processor 401 and the memory 402 communicate with each other via a bus. The memory 402 stores program instructions for maintaining a constant temperature of an objective lens in a charged particle beam system. When the program instructions are executed by the processor 401, the method steps described in the above text in combination with the accompanying drawings are implemented: determining the maximum ampere-turns required for the coil of the objective lens to generate a magnetic field and determining the total heating power of the objective lens according to the maximum ampere-turns; obtaining the number of coil turns and resistance value corresponding to each coil of the coarse adjustment coil, the fine adjustment coil and the power compensation coil; and coordinating the current value corresponding to each coil of the coarse adjustment coil, the fine adjustment coil and the power compensation coil according to the target ampere-turns, the total heating power, the number of coil turns and resistance value corresponding to each coil, so as to maintain the constant temperature of the objective lens.

[0055] According to the above description in combination with the accompanying drawings, those skilled in the art can also understand that the embodiments of the present application can also be implemented by a software program. Therefore, the present application also provides a computer-readable storage medium. The computer-readable storage medium stores thereon computer-readable instructions for maintaining a constant temperature of an objective lens in a charged particle beam system. When the computer-readable instructions are executed by one or more processors, the present application in combination with the accompanying drawings can be implemented. Figure 1 A method for maintaining a constant temperature of an objective lens in a charged particle beam system is described.

[0056] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0057] It should be noted that although the operations of the method of the present application are described in a specific order in the accompanying drawings, this does not require or imply that the operations must be performed in this specific order, or that all the operations shown must be performed to achieve the desired results. On the contrary, the steps depicted in the flow chart can be performed in a different order. Additionally or alternatively, some steps can be omitted, multiple steps can be combined into one step, and / or one step can be decomposed into multiple steps.

[0058] It should be understood that when the terms "first", "second", "third" and "fourth" are used in the claims, the specification and the drawings of the present application, they are only used to distinguish different objects, rather than to describe a specific order. The terms "include" and "comprise" used in the specification of the present application indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections.

[0059] It should also be understood that the terms used in this specification of the application are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in the specification of the application, the singular forms of "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise. It should also be further understood that the term "and / or" used in the specification of the application refers to any combination of one or more of the associated listed items and all possible combinations, including these combinations.

[0060] Although the implementation methods of this application are as above, the contents are only examples adopted to facilitate the understanding of this application, and are not intended to limit the scope and application scenarios of this application. Any technician in the technical field described in this application can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in this application, but the scope of patent protection of this application shall still be based on the scope defined in the attached claims.

Claims

1. A method for maintaining a constant temperature of an objective lens in a charged particle beam system, characterized in that: The objective lens comprises a coarse adjustment coil, a fine adjustment coil and a power compensation coil, the power compensation coil has an opposite magnetic field to the coarse adjustment coil and the fine adjustment coil, and the method comprises: Determining the maximum ampere-turns required for the coil of the objective lens to generate a magnetic field and determining the total heating power of the objective lens according to the maximum ampere-turns; Obtaining the number of coil turns and resistance values ​​corresponding to each of the coarse adjustment coil, the fine adjustment coil and the power compensation coil; and, Coordinate the current values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil according to the target ampere-turns, the total heating power, the coil turns and the resistance value corresponding to each coil to maintain the constant temperature of the objective lens, The current values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil are set to a maximum excitation value, and the total heating power of the objective lens is determined by the following operations: Acquire the maximum excitation value of the current value corresponding to each of the coarse adjustment coil and the fine adjustment coil according to the maximum ampere-turns; and The total heating power of the objective lens is calculated based on the maximum excitation value of the respective corresponding current values ​​and the respective corresponding resistance values ​​of the coarse adjustment coil and the fine adjustment coil; Wherein, coordinating the current values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil according to the target ampere-turns, the total heating power, the coil turns and the resistance value corresponding to each coil includes: coordinating the current values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil according to the following formula: in, represents the target ampere-turns, represents the total heating power of the objective lens, , and respectively represent the current values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil, , and Respectively represent the number of coil turns corresponding to each coil of the coarse adjustment coil, the fine adjustment coil and the power compensation coil; , and Respectively represent the resistance values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil.

2. The method according to claim 1, characterized in that The power compensation coil, the coarse adjustment coil, and the fine adjustment coil have opposite magnetic fields through the following operations: The winding direction of the power compensation coil is set to be opposite to the winding direction of the coarse adjustment coil and the fine adjustment coil; or, The direction of the current flowing into the power compensation coil is opposite to the direction of the current flowing into the coarse adjustment coil and the fine adjustment coil.

3. The method according to claim 1, characterized in that The resistance values ​​corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil are calculated based on the coil lengths and wire cross-sectional areas corresponding to the coarse adjustment coil, the fine adjustment coil and the power compensation coil.

4. A constant temperature objective lens, characterized in that: At least: A coarse adjustment coil, a fine adjustment coil and a power compensation coil, wherein the power compensation coil has an opposite magnetic field to the coarse adjustment coil and the fine adjustment coil, wherein the coarse adjustment coil, the fine adjustment coil and the power compensation coil cooperate under the method according to any one of claims 1-3 to keep the constant temperature of the constant temperature objective lens.

5. A charged particle beam system, characterized in that: include: The thermostatic objective lens according to claim 4.

6. A device for maintaining a constant temperature of an objective lens in a charged particle beam system, characterized in that: include: processor; as well as, A memory storing computer instructions for maintaining a constant temperature of an objective lens in a charged particle beam system, wherein when the computer instructions are executed by a processor, the device implements the method according to any one of claims 1 to 3.

7. A computer-readable storage medium, characterized in that: Computer program instructions for maintaining a constant temperature of an objective lens in a charged particle beam system are stored thereon, and when the computer program instructions are executed by one or more processors, the method according to any one of claims 1-3 is implemented.

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