Charged Particle Gun and Charged Particle Beam System

Abstract

The present invention provides an electron gun (901) and a length-measuring SEM (900) capable of suppressing non-uniform temperature distribution in an extraction electrode. The electron gun (901) includes: a charged particle source (1); an extraction electrode (3) that extracts charged particles from the charged particle source (1), allows a part of the charged particles to pass through, and shields another part of the charged particles; and an auxiliary structure (5) that contacts the extraction electrode (3). The length-measuring SEM (900) includes the above-described electron gun (901) and a computer system (920) that controls the electron gun (901).

Description

Technical Field

[0001] The present disclosure relates to a charged particle gun and a charged particle beam system. Background Art

[0002] Currently, in the semiconductor inspection device market, the observation area of wafers is increasing. Particularly in EUV lithography using extreme ultraviolet light, observation of the entire surface of the wafer is necessary. Therefore, at the current device throughput, inspection of defects and dimensions takes several days to several tens of days. Thus, in semiconductor inspection devices, in addition to improving the throughput of the inspection device, the ability to operate stably for a long time, that is, the ability to perform inspections and measurements continuously with high precision for a long time, has become an important indicator for determining the value of the device.

[0003] Here, as an element supporting the long-term stable operation of the device, stable charged particle emission can be cited. When the charged particle emission shows unstable behavior, the observation result changes and the inspection result becomes unstable. Therefore, in order to continuously perform high-precision inspections for a long time, it is necessary to keep the quality of the specimen observation result constant at all times. To achieve this purpose, a charged particle gun capable of stably providing charged particle emission for a long time is required.

[0004] As an example of a technique for improving the stability of such charged particle emission, there is the technique described in Patent Document 1. In Patent Document 1, the operating stability of the charged particle gun is improved by aligning the central axes of the extraction electrode and the suppressor with the central axis of the needle electrode. An electric field is symmetrically applied to the needle electrode about the central axis to achieve stable charged particle emission.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2002-216686 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] However, in the prior art, there is a problem of generating a non-uniform temperature distribution in the extraction electrode.

[0010] In order to increase the throughput of the device, it is effective to increase the amount of charged particles released from the charged particle source and observe the specimen at high speed. However, when increasing the amount of charged particles released from the charged particle source, heat generation and thermal expansion of the extraction electrode occur, which may hinder the stable operation of the charged particle gun.

[0011] More than 99% of the charged particles released from the charged particle source collide with the extraction electrode, and thus a current caused by the inflow and outflow of electrons is generated in the extraction electrode. For the extraction electrode, a voltage of several kV is always applied in order to extract charged particles from the charged particle source. Therefore, power is generated by the applied voltage and the current generated by the charged particles, causing heat generation inside the extraction electrode.

[0012] Here, regarding the power W generated by charged particle irradiation, the applied voltage is set as V, the current generated by the charged particles is set as I, and it is obtained by the following formula.

[0013] W = V × I... Equation (1)

[0014] As an example, when a current of 500 μA is generated in an extraction electrode to which a voltage of 3 kV is applied, the power generated in the extraction electrode is 1.5 W, and the temperature rise caused by heat generation exceeds 100°C.

[0015] The main shape of the extraction electrode is a cup-shaped structure as shown in Patent Document 1, and charged particles collide with the surface arranged perpendicular to the optical axis to generate heat. The thermal conductivity of the heat conduction of the extraction electrode is small, and the inside of the charged particle gun is in a vacuum state, so it becomes a heat-insulated state and the amount of heat radiation is small. Therefore, the heat generated in the extraction electrode cannot escape, and heat accumulates in the part where charged particles are irradiated (charged particle irradiation part), and only the temperature of the charged particle irradiation part becomes high. Therefore, under the operating conditions of the charged particle gun in high-throughput observation, the temperature of the charged particle irradiation part becomes high, and a temperature gradient is generated where the temperature becomes lower as the distance from the charged particle irradiation part increases. As a result, a non-uniform temperature distribution inside the extraction electrode is generated.

[0016] In Patent Document 1, the extraction electrode is connected to the extraction electrode base by screws. In such a structure, since the heat conduction around the screws is small, a temperature difference is generated between the extraction electrode and the extraction electrode base. Therefore, in the structure shown in Patent Document 1, local thermal expansion caused by non-uniform temperature distribution is also generated.

[0017] In Patent Document 1, it is described that the central axis of the extraction electrode is continuously aligned with the central axis of the needle electrode. However, in the case of increasing the release amount of charged particles in order to achieve high throughput, due to non-uniform thermal expansion inside the extraction electrode, it is difficult to continuously align the respective central axes. As a result, it is difficult to operate the charged particle gun stably, machine time is lost, and maintenance work for aligning the central axis of the charged particle source with the central axis of the extraction electrode needs to be performed frequently.

[0018] The present disclosure has been completed to solve such problems, and an object thereof is to provide a charged particle gun and a charged particle beam system capable of suppressing non-uniform temperature distribution in the extraction electrode.

[0019] Means for Solving the Problem

[0020] An example of the charged particle gun of the present disclosure includes:

[0021] A charged particle source;

[0022] An extraction electrode that extracts charged particles from the charged particle source, allows a part of the charged particles to pass through, and shields another part of the charged particles; and

[0023] A heat transfer structure that contacts the extraction electrode.

[0024] Moreover, an example of the charged particle beam system of the present disclosure includes:

[0025] The above-mentioned charged particle gun;

[0026] A computer system that controls the charged particle gun.

[0027] Advantageous Effects of the Invention

[0028] The charged particle gun and the charged particle beam system of the present disclosure equalize the temperature of the extraction electrode by increasing the heat conduction of the charged particle irradiation portion of the extraction electrode. As a result, thermal expansion of the extraction electrode is suppressed or equalized, so that the amount of charged particles released from the charged particle source remains fixed or the variation becomes smaller. Consequently, even when the amount of charged particles is large, the charged particle gun and the charged particle beam system operate stably for a long time, thus improving productivity and maintainability.

[0029] In this way, it is possible to increase the amount of charged particles released from the charged particle gun, improve the throughput of the charged particle gun and the charged particle beam system, and perform high-precision operations (such as high-precision inspections and measurements) for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Structural examples of the electron guns of Examples 1, 4, and 9.

[0031] Figure 2 Examples of the heat generation conditions of a charged particle gun having a conventional structure as a comparative example.

[0032] Figure 3 Comparison results of the temporal change in the release amount of charged particles.

[0033] Figure 4 Structural examples of the electron guns of Example 2.

[0034] Figure 5 Structural examples of the electron guns of Example 3.

[0035] Figure 6 Structural examples of the electron guns of Example 5.

[0036] Figure 7 It is a structural example of the electron gun in Examples 6 to 8.

[0037] Figure 8 It is a structural example of the electron gun in Example 10.

[0038] Figure 9 It is a structural example of the charged particle beam system in Example 1. Detailed implementation mode

[0039] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, elements having the same function are sometimes denoted by the same reference numerals or corresponding reference numerals. In addition, in the drawings used in the following embodiments, even in the top view, in order to easily observe the drawings, hatching may sometimes be marked. In addition, the drawings show embodiments in accordance with the principles of the present disclosure, but these are for understanding the present disclosure and are by no means used to limitatively interpret the present disclosure. The description in this specification is merely a typical example and does not limit the scope of patent protection or application examples of the present disclosure in any sense.

[0040] In the following embodiments, a detailed description is given for those skilled in the art to implement the present disclosure. However, it should be understood that other installations or methods are also possible, and structural or constructional changes and replacement of various elements can be made without departing from the scope and spirit of the technical idea of the present disclosure. Therefore, the following description should not be construed as being limited thereto.

[0041] In addition, in the description of the following embodiments, an example is shown in which the charged particle gun (electron gun unit) of the present disclosure is applied to a charged particle beam system (pattern measurement system) composed of a scanning electron microscope (SEM: Scanning Electron Microscope) using an electron beam and a computer system. However, this embodiment should not be limitatively interpreted. For example, the present disclosure can also be applied to a wafer defect inspection system, a device using a charged particle beam such as an ion beam, a general observation device, etc.

[0042] Example 1

[0043] As an example of the charged particle beam system of the present disclosure, taking a critical-dimension scanning electron microscope (CD-SEM), which is used for measuring the dimensions of gates and contact holes in semiconductor devices, as an example, Figure 9 the structure and principle of the CD-SEM 900 of the present disclosure will be described.

[0044] Figure 9Fig. 0 shows a structural example of the charged particle beam system of Example 1. In this example, the charged particle beam system is configured as a length measuring SEM900. The length measuring SEM900 includes an electron gun 901 (charged particle gun). In addition, in this embodiment, electrons are used as an example of charged particles, but it can also be applied to charged particle guns that emit other charged particles.

[0045] Electrons are released as charged particles from the electron gun 901 held in a housing 924 maintained at a high vacuum. The released electrons are accelerated by a primary electron acceleration electrode 926 to which a high voltage is applied by a high voltage power supply 925. The electron beam 906 (charged particle beam) is converged by an electron lens 927 for convergence. Thereafter, the beam current amount of the electron beam 906 is adjusted by an aperture 928. Thereafter, the electron beam 906 is deflected by a scanning coil 929, and two-dimensionally scanned on a wafer 905 (semiconductor wafer) as a specimen.

[0046] An electron objective lens 930 is disposed directly above the wafer 905. The electron beam 906 is converged by the electron objective lens 930, focused, and incident on the wafer 905. Secondary electrons 931 generated as a result of the incidence of primary electrons (electron beam 906) are detected by a secondary electron detector 932. The amount of the detected secondary electrons reflects the shape of the specimen surface, so the shape of the surface can be imaged based on the information of the secondary electrons.

[0047] The wafer 905 is held on an electrostatic chuck 907 while ensuring a certain flatness and fixed on an X-Y stage 904. In addition, Figure 9 it is described in a cross-sectional view of the housing and its internal structure as viewed from the side. The wafer 905 can move freely in both the X direction and the Y direction, and any position within the wafer surface can be measured. In addition, the X-Y stage 904 includes a wafer transfer lifting mechanism 933. An elastomer capable of moving up and down is assembled in the wafer transfer lifting mechanism 933. Using this elastomer, the wafer 905 can be loaded and unloaded with respect to the electrostatic chuck 907. Through the coordinated operation of the wafer transfer lifting mechanism 933 and the transfer robot 934, the wafer 905 can be transferred between the loading chamber 935 (preliminary evacuation chamber).

[0048] The following describes the operation when the wafer 905 to be measured is transferred to the electrostatic chuck 907. First, the wafer 905 set in the wafer cassette 936 is carried into the loading chamber 935 by a transfer robot 938 of a microenvironment 937 (minienvironment). In the loading chamber 935, evacuation and atmospheric opening can be performed by a vacuum exhaust system (not shown). By opening and closing a valve (not shown) and the operation of the transfer robot 934, the wafer 905 is transferred onto the electrostatic chuck 907 while maintaining the vacuum degree inside the housing 924 at a level that is practically acceptable.

[0049] A surface potentiometer 939 is mounted on the housing 924. The surface potentiometer 939 is fixed by adjusting the position in the height direction in such a manner that the distance from the probe tip to the electrostatic chuck 907 or the wafer 905 is appropriate, and can measure the surface potential of the electrostatic chuck 907 or the wafer 905 in a non-contact manner.

[0050] The length-measuring SEM 900 may also include a computer system 920 for controlling the electron gun 901. Each component of the above-described length-measuring SEM 900 can be implemented using a general-purpose computer. Each component can also be implemented as a function of a program executed on a computer. In Figure 9 the example, the structure of the control system is implemented by the computer system 920. The computer system 920 includes at least a processor such as a CPU (Central Processing Unit), a storage unit such as a memory, and a storage device such as a hard disk (including an image storage unit).

[0051] Moreover, for example, the computer system 920 can be configured as a multi-processor system. Also, the control of each component of the electro-optical system within the housing 924 can be implemented by the main processor. Additionally, the control related to the X-Y stage 904, transfer robots 934, 938, and the surface potentiometer 939 can be implemented by a sub-processor. Additionally, the image processing for generating an SEM image based on the signal detected by the secondary electron detector 932 can be implemented by a sub-processor.

[0052] In addition, the computer system 920 has an input device for user input of instructions, etc., and a display device for displaying a GUI screen for inputting these and SEM images, etc. The input device can be used by the user to input data and instructions, and is, for example, a mouse, keyboard, voice input device, etc. The display device is, for example, a display unit. Such an input / output device (user interface) can also be a touch panel capable of performing data input and display.

[0053] Figure 1 Indicates Figure 9 a structural example of the electron gun 901. The electron gun 901 includes an extraction electrode 3. The extraction electrode 3 includes a cylindrical first part 3a and a conical or planar second part 3b (planar in this example). In addition, the electron gun 901 includes an auxiliary structure 5. The extraction electrode 3 and the auxiliary structure 5 are arranged to be rotationally symmetric or substantially rotationally symmetric about the central axis A.

[0054] The auxiliary structure 5 is in contact with the extraction electrode 3. In Figure 1In the example, the auxiliary structure 5 is arranged so as to cover the extraction electrode 3. In the present embodiment, the auxiliary structure 5 is composed of a single auxiliary component. Further, in the present embodiment, the auxiliary structure 5 is in contact with the first portion 3a and the second portion 3b of the extraction electrode 3.

[0055] Further, in the present embodiment, the auxiliary structure 5 is arranged outside the extraction electrode 3. "Outside the extraction electrode 3" means, for example, a region or position on the side opposite to the charged particle source 1 with respect to the extraction electrode 3 (that is, the charged particle source 1 is arranged inside the extraction electrode 3). Thus, charged particles do not collide with the auxiliary structure 5, so that the cause of the operation of the charged particle gun becoming unstable can be reduced. Further, heat generation of the auxiliary structure 5 can also be suppressed.

[0056] The electron gun 901 includes a charged particle source 1 that releases charged particles (electrons in this example). Further, although not shown in Figure 1 , the electron gun 901 has a mechanism for aligning the central axis of the charged particle source 1 with the central axis of the extraction electrode 3 in the direction of the voltage application unit shown in Figure 1 . The charged particle source 1 is held by a charged particle source holding member 7.

[0057] The extraction electrode 3 has a passing portion 3c through which a part of the charged particles passes. The passing portion 3c is, for example, a circular opening. A part of the charged particle beam 2 released from the charged particle source 1 passes through the passing portion 3c, but the remaining part collides with the extraction electrode 3. That is, the extraction electrode 3 extracts charged particles from the charged particle source 1, allows a part of the charged particles to pass through, and shields the other part of the charged particles.

[0058] Since a high voltage is applied to the extraction electrode 3, current is generated by the collision of the charged particle beam 2 and heat is generated. In the conventional structure, the heat transfer path of the generated heat is only the heat conduction path 4 that transfers inside the extraction electrode 3, but in the present embodiment, there is newly a heat transfer path 6 that transfers inside the auxiliary structure 5 through contact with the outer surface of the extraction electrode 3. Therefore, the thermal conductivity of the heat transfer becomes larger, and a local temperature rise of the extraction electrode 3 is suppressed. Thus, the auxiliary structure 5 functions as a heat transfer structure.

[0059] Therefore, thermal expansion of the extraction electrode 3 is suppressed, and the central axis of the extraction electrode 3 and the central axis of the charged particle source 1 do not change from the state after the initial adjustment and remain aligned. Thereby, the charged particle source 1 can stably release the charged particle beam 2.

[0060] The auxiliary structure 5 has an opening 5c through which a part of the charged particles pass. The opening 5c is, for example, a circular opening. When observed from the optical axis direction, the opening 5c includes the entirety of the passing portion 3c of the extraction electrode 3. For example, by forming both the passing portion 3c and the opening 5c into a circular shape, making the diameter of the opening 5c larger than the diameter of the passing portion 3c, and concentrically arranging the passing portion 3c and the opening 5c, such a structure is achieved. In this way, the charged particles do not collide with the auxiliary structure 5, so the reasons for the unstable operation of the charged particle gun can be reduced. In addition, the heat generation of the auxiliary structure 5 can also be suppressed.

[0061] In Figure 2 , as a comparative example, an example of the heat generation state of a charged particle gun having a conventional structure is shown. Figure 2 (a) of Figure 2 shows the heat generation state, and Figure 1 (b) of

[0062] In Figure 2 (a) of Figure 2 , the relationship between the power generated by the extraction electrode 3 and the temperature is shown. In Figure 2 (a) of Figure 2 , the horizontal axis represents the power and the vertical axis represents the temperature. The power is obtained by the above formula (1). In

[0063] According to Figure 2 (a) of

[0064] In Figure 2 (b) of

[0065] Figure 3 Shows the comparison results of the change over time of the release amount of charged particles. Figure 3 (a) of is the result of a structure without the auxiliary structure 5 as a comparative example (e.g., Figure 2 the structure shown), Figure 3 (b) of is the result of a structure with the auxiliary structure 5 (e.g., the structure of Example 1).

[0066] The solid line represents the current amount released from the electron source, and the dashed line represents the power calculated according to Equation (1). Electrons are released by applying a voltage to the electron source, and the change over time of the current amount released from the electron source is measured.

[0067] In Figure 3 the case shown in (a) (without the auxiliary structure 5), it can be seen that if the power is increased, the current amount decreases at the time point when the power becomes less than 1 W, showing unstable behavior. In Figure 3 in (a), the current amount becomes smaller, which is presumably because the extraction electrode 3 undergoes thermal expansion, thereby changing the positional relationship between the charged particle source 1 and the extraction electrode 3.

[0068] In contrast, in Figure 3 the case shown in (b) (with the auxiliary structure 5), the power is increased to a high power of about 6.5 W after about 0.5 days, but it can be seen that even if this high power is maintained, the current remains stable for a long time. It can be seen that at such a high power, in the structure without the auxiliary structure 5, a temperature difference of more than 200 °C is generated in the extraction electrode 3, and the current becomes unstable, but in the structure with the auxiliary structure 5, stable release of charged particles can be provided.

[0069] In addition, in Figure 3 (b) only shows the data up to the fifth day, but the inventors have confirmed that even if the operation continues for more than 1 year in this state, the power does not change. Based on these results, it can be said that the electron gun 901 of Example 1 contributes to the long-term stable operation of the charged particle beam system in a device for high-throughput observation conditions that require a large amount of charged particles.

[0070] Therefore, according to the electron gun 901 and the length-measuring SEM 900 of the present embodiment, an uneven temperature distribution in the extraction electrode can be suppressed. Especially in Figure 1 the example of, the auxiliary structure 5 is in contact with both the first part 3a and the second part 3b of the extraction electrode 3, so the heat conduction from the second part 3b near the front end to the first part 3a on the root side is promoted, further equalizing the temperature distribution. In this way, it is possible to achieve both high throughput of the device by increasing the release amount of charged particles and long-term stable operation based on stable release of charged particles.

[0071] Example 2

[0072] Example 2 is an example in which a part of the structure around the extraction electrode 3 is changed in Example 1. Hereinafter, the differences from Example 1 will be described.

[0073] Figure 4 Fig. shows a structural example of the electron gun of Example 2. The electron gun includes a conductive member 20 for applying a voltage to the extraction electrode 3. The conductive member 20 is, for example, called a voltage introduction electrode. The extraction electrode 3 is fixed to the conductive member 20 by a screw 21. The heat generated by the extraction electrode 3 is conducted to the conductive member 20 through the screw 21 as shown by the heat transfer path 22 in the screw 21.

[0074] However, the contact area between the screw 21 and the conductive member 20 is small and the thermal conductivity is low. Therefore, by bringing the auxiliary structure 5 into contact with the extraction electrode 3 and the conductive member 20 to further increase the contact area, the thermal conductivity can be significantly improved, and the temperature rise of the extraction electrode 3 can be more effectively suppressed. By suppressing the temperature rise of the extraction electrode 3, thermal expansion is suppressed, and stable electron emission is obtained from the charged particle source 1.

[0075] Here, the screw 21 is a fixing member for fixing the extraction electrode 3 and the conductive member 20 to each other, but it may be configured to function as an adjustment mechanism for adjusting the positional relationship between the extraction electrode 3 and the conductive member 20. For example, as Figure 4 shown, in a state where the extraction electrode 3 and the conductive member 20 are in contact with each other and the central axis A3 of the extraction electrode 3, the central axis A20 of the conductive member 20, and the central axis A1 of the charged particle source 1 are aligned, the screw 21 adjusts and fixes the positional relationship between the extraction electrode 3 and the conductive member 20. In this way, the positional relationship between the extraction electrode 3 and the conductive member 20 can be easily adjusted.

[0076] In addition, the auxiliary structure 5 is arranged so as to cover the extraction electrode 3. Therefore, the relative position between the charged particle source 1 and the extraction electrode 3 can be adjusted first, and then the auxiliary structure 5 can be installed. Therefore, the installation of the auxiliary structure 5 does not affect the matching of the central axis of the charged particle source 1 and the central axis of the extraction electrode 3.

[0077] The orientation of the arrangement of the screw 21 can be arbitrarily changed, and the extraction electrode 3 can be fixed to the conductive member 20 from any direction. In Figure 4 , the screw 21 is inserted from the outside toward the inside in the radial direction of the optical axis, but the screw 21 can also be inserted into the extraction electrode 3 in the optical axis direction, for example, from the side opposite to the charged particle source 1 toward the direction of the charged particle source 1.

[0078] Example 3

[0079] Example 3: The structure of the auxiliary structure 5 is changed in Example 1 and is composed of multiple components. Hereinafter, the differences from Example 1 will be described.

[0080] Figure 5 Structural examples of the electron gun of two types of Example 3 are shown. Figure 5 In (a) of Figure 5 and any of the electron guns in (b) of Figure 5 in (a) of Figure 5 and any of the structures in (b) of

[0081] In Figure 5 the example of (a), the auxiliary structure is divided into multiple components, and includes a first auxiliary component 33 and a second auxiliary component 34. The first auxiliary component 33 and the second auxiliary component 34 are fixed in contact with each other. The first auxiliary component 33 is in contact with the plate-shaped extraction electrode 31, and the second auxiliary component 34 is in contact with the conductive component 32. Through these auxiliary components, the heat generated by the plate-shaped extraction electrode 31 is efficiently conducted to the conductive component 32. The first auxiliary component 33 and the second auxiliary component 34 can be fixed by, for example, screws, welding, etc.

[0082] Here, in Figure 5 the example shown in (a) of

[0083] In Figure 5 the shape of the plate-shaped extraction electrode 31 and the conductive component 32 in (a) of

[0084] In Figure 5 (b) of

[0085] In addition, in Figure 5 the example of (a) andFigure 5 In (b) thereof, the conductive member 32 has a rod shape, but the shape and the number are not limited to those shown in the figure. For example, the conductive member 32 may have a cylindrical shape or a prismatic shape, and may be any number as long as the number is one or more.

[0086] In addition, the number of auxiliary members constituting the auxiliary structure is not limited. In addition, it is not necessary for the materials of the respective auxiliary members to be the same.

[0087] Example 4

[0088] Example 4 is an example in which the material of the auxiliary structure 5 is specified in Example 1. Hereinafter, the differences from Example 1 will be described.

[0089] In Example 4, as Figure 1 shown, the auxiliary structure 5 includes a material having a thermal conductivity of 10 W / mK or more. For example, the entire auxiliary structure 5 is made of such a material. As the material of the lead-out electrode 3, SUS or titanium is generally widely used. Therefore, the auxiliary structure 5 preferably includes such a material having a high thermal conductivity. In particular, materials having high thermal conductivity such as copper, silver, aluminum, and gold are effective.

[0090] Example 4 can be similarly applied to the auxiliary structure 5 in Example 2, and can also be similarly applied to the first auxiliary member 33 and the second auxiliary member 34 in Example 3.

[0091] Example 5

[0092] Example 5 is an example in which fins are provided on the auxiliary structure 5 in Example 1. Hereinafter, the differences from Example 1 will be described.

[0093] Figure 6 The structural example of the electron gun showing Example 5 is shown. In the present embodiment, the surface area of the auxiliary structure is increased, and the heat radiation efficiency is improved. More specifically, the auxiliary structure 41 includes a heat sink 41a. Through the heat sink 41a, the efficiency of heat radiation is improved. As the shape of the heat sink 41a, a disc shape is preferred in consideration of workability, but it does not need to be a disc shape. It may be a polygonal shape or a protrusion shape.

[0094] As the surface area of the heat sink 41a, it is preferably set to 420 mm 2 or more. In the Figure 6 example, there is one heat sink 41a, but two or more heat sinks may be provided. The auxiliary structure may also be configured such that the fins are independent members, and the fins can be detached from the auxiliary structure main body.

[0095] In addition, in the present embodiment, the auxiliary structure 41 includes a heat sink 41a. However, instead of or in addition to this, the extraction electrode 3 may include a heat sink. Further, in the case where the electron gun includes a conductive member (e.g., Figure 4 the conductive member 20, etc.), the conductive member may also include a heat sink.

[0096] Embodiment 6

[0097] Embodiment 6 is an example in which a specific structure is provided on the surface of the auxiliary structure 5 in Embodiment 1. Hereinafter, the differences from Embodiment 1 will be described.

[0098] Figure 7 (a) to (c) of Figure 7 show structural examples of the electron gun of Embodiment 6. As shown in

[0099] (b) of Figure 7 , in the auxiliary structure 5, a heat conduction layer 51 containing a material having a heat conductivity of 10 W / mK or more is formed on at least a part of the surface in contact with the extraction electrode 3 and the conductive member 20.

[0100] In addition, as shown in

[0101] (c) of

[0102] , the screw 21 includes a heat conduction layer 51. The heat conduction layer 51 is provided, for example, on the surface of the screw 21. As a more specific example, it is provided on the entire radially outer surface of the screw head. Thus, in the present embodiment, the screw 21 includes a heat transfer structure. The screw 21 is arranged such that the heat conduction layer 51 is in contact with both the extraction electrode 3 and the conductive member 20.

[0103] Thus, by providing the heat conduction layer 51 having a particularly high heat conductivity on the surface of the auxiliary structure 5 and also providing the heat conduction layer 51 on the surface of the screw 21, the efficiency of heat conduction can be further improved, and the heat generated by the extraction electrode can be conducted more effectively. The heat conduction layer 51 can be made of, for example, metal. The heat conduction layer 51 preferably contains a material having a heat conductivity of 10 W / mK or more. Examples of such materials include metals having a large heat conductivity such as indium, silver, molybdenum, hafnium, aluminum, nickel, tungsten, gold, and copper. The film formation method and thickness of the heat conduction layer 51 shown in Embodiment 6 are not limited. Examples of the film formation method include sputtering, vacuum evaporation, plating, etc. In particular, the heat conduction layer 51 is preferably made of a material having a higher heat conductivity than the other parts (i.e., the parts other than the heat conduction layer 51 in the auxiliary structure 5 and the parts other than the heat conduction layer 51 in the screw 21). As such a material, copper is preferred.In addition, the heat-conducting layer 51 of the auxiliary structure 5 is preferably formed over the entire surface in contact with the lead-out electrode 3 and the conductive member 20, but may also be formed over at least a part of such a surface. Similarly, the heat-conducting layer 51 of the screw 21 is preferably formed over the entire surface in contact with the lead-out electrode 3 and the conductive member 20, but may also be formed over at least a part of such a surface.

[0104] As a modification of Example 6, the heat-conducting layer 51 of the auxiliary structure 5 may also be formed only on the surface in contact with either the lead-out electrode 3 or the conductive member 20. In addition, either the heat-conducting layer 51 of the auxiliary structure 5 or the heat-conducting layer 51 of the screw 21 may be omitted.

[0105] The heat-conducting layer 51 used in Example 6 can also be utilized when the auxiliary structure is divided into a plurality of components. In such a case, the heat-conducting layer 51 may also be provided on the contact surface between the auxiliary components. Thus, the efficiency of heat conduction between the auxiliary components is improved. In addition, in such a structure, the materials of the heat-conducting layers 51 of the respective auxiliary components do not need to be the same.

[0106] Example 7

[0107] Example 7 is an example in which a specific structure is provided on the surface of the auxiliary structure 5 in Example 1. Hereinafter, the differences from Example 1 will be described.

[0108] Figure 7 of (a) and Figure 7 of (d) show structural examples of the electron gun of Example 7. A metal layer 52 is provided on the outer surface of the auxiliary structure 5 (particularly the surface not in contact with the lead-out electrode 3). The metal layer 52 is made of a material different from the part other than the metal layer 52 in the auxiliary structure 5.

[0109] As a specific example, the metal layer 52 can be configured to include a metal having an emissivity of 0.1 or more. Thus, in addition to the heat conduction inside the auxiliary structure 5, the heat of the lead-out electrode 3 can be dissipated by the heat radiation of the metal layer 52, and the temperature rise of the lead-out electrode 3 can be suppressed to a smaller extent. As the material of the metal layer 52, a metal having a large emissivity is preferred, for example, nickel, stainless steel, chromium, brass, etc. are preferred.

[0110] In Example 7, the auxiliary structure 5 may also be divided into a plurality of auxiliary components. In this case, the materials of the metal layer 52 do not need to be the same in all the auxiliary components.

[0111] Example 7 may also be implemented in combination with Example 6. In this case, the materials of the heat-conducting layer 51 and the metal layer 52 do not need to be the same.

[0112] If Example 7 is combined with Example 5, the efficiency of heat radiation can be further improved.

[0113] In addition, the metal layer 52 is preferably formed on the entire outer surface of the auxiliary structure 5 (specifically, the entire surface that does not contact the lead-out electrode 3), but may also be formed on at least a part of the outer surface.

[0114] Example 8

[0115] Example 8 is an example in which the material of the auxiliary structure main body is defined in Example 6 or 7. Hereinafter, the differences from Examples 6 and 7 will be described.

[0116] As Figure 7 (Examples 6 and 7) As shown, when the heat conductive layer 51 or the metal layer 52 is provided on the surface of the auxiliary structure (the auxiliary structure 5 or the screw 21), as the material of the other parts in the auxiliary structure, a material with a small specific heat and a small density (that is, a material with a small heat capacity) is preferably used. For example, the auxiliary structure preferably contains a material with a specific heat of 0.6 J / kgK or less and a specific gravity of 5 g / cm 3 or less. The entire auxiliary structure may also be made of such a material.

[0117] As a representative material, titanium can be cited. Since titanium has a small heat capacity, its temperature rises rapidly, but due to its low thermal conductivity, it has the characteristic that the parts far from the heat source are difficult to heat up. Therefore, in a material with a small heat capacity such as titanium, by forming a heat conductive layer 51 or a metal layer 52 that conducts heat on its surface, heat can be uniformly transferred to the entire auxiliary structure. As a result, the temperature of the entire auxiliary structure rises in a short time, and thus the heat conduction performance as a heat transfer structure becomes good.

[0118] Example 9

[0119] Example 9 is an example in which the surface treatment is performed on the auxiliary structure 5 in Example 1. Hereinafter, the differences from Example 1 will be described.

[0120] As Figure 1 shown, in Example 9, in order to increase the emissivity, the surface treatment was performed on the auxiliary structure 5. The surface treatment is a treatment for reducing the surface roughness, for example, mirror finishing. In particular, if mirror finishing is performed, the emissivity becomes large, and thus the heat radiation becomes large. When the surface of the electrode is rough, there is a possibility of discharge of the charged particle gun, but the discharge can be suppressed by the surface treatment, and thus the operation is more stable.

[0121] Example 10

[0122] Example 10 is an example in which an electrode for adjusting the amount of charged particles is additionally provided in Example 1. Hereinafter, the differences from Example 1 will be described.

[0123] Figure 8Fig. 0 shows a structural example of the electron gun of Embodiment 10. The electron gun includes an electrode 61 (adjustment electrode) for adjusting the amount of charged particles. The electrode 61 for adjusting the amount of charged particles has a function of adjusting the electric field strength at the front end of the charged particle source 1 or a function of adjusting the amount of charged particles released from the charged particle source 1. For example, the electrode 61 for adjusting the amount of charged particles can adjust the amount of charged particles released from the charged particle source 1 by adjusting the electric field strength around the front end of the charged particle source 1. The electrode 61 for adjusting the amount of charged particles can also be referred to as a suppressor, for example.

[0124] Although not particularly shown in Figure 8 the electron gun has a mechanism for adjusting the positions of the charged particle source 1 and the extraction electrode 3 in the direction of the voltage application unit. In addition, the electron gun also has a mechanism for adjusting the position of the electrode 61 for adjusting the amount of charged particles. Such a structure can be combined with any one of Embodiments 1 to 9.

[0125] According to Embodiment 10, the intensity of the charged particle beam can be adjusted more appropriately.

[0126] As described above, in the description of Embodiments 1 to 10, combinations of specific embodiments have been described, but each embodiment can be implemented in any combination.

[0127] Symbol Explanation

[0128] 1 Charged particle source

[0129] 2 Charged particle beam

[0130] 3 Extraction electrode

[0131] 3a First part

[0132] 3b Second part

[0133] 3c Passage part

[0134] 4 Heat conduction path

[0135] 5 Auxiliary structure (heat transfer structure)

[0136] 5c Opening

[0137] 6 Heat transfer path

[0138] 8 Temperature measurement part

[0139] 9 Charged particle irradiation part

[0140] 20 Conductive member

[0141] 21 Screw (heat transfer structure)

[0142] 22 Heat transfer path

[0143] 31 Plate-shaped lead-out electrode (lead-out electrode),

[0144] 32 Conductive component,

[0145] 33 First auxiliary component (heat transfer structure),

[0146] 34 Second auxiliary component (heat transfer structure),

[0147] 35 Heat conduction terminal (heat transfer structure),

[0148] 51 Heat conduction layer,

[0149] 52 Metal layer,

[0150] 41 Auxiliary structure (heat transfer structure),

[0151] 41a Heat sink,

[0152] 61 Electrode for adjusting the amount of charged particles (adjusting electrode),

[0153] 900 Length measurement SEM (charged particle beam system),

[0154] 901 Electron gun (charged particle gun),

[0155] 920 Computer system,

[0156] A, A1, A3, A20 Central axes.

Claims

1. A charged particle gun, characterized in that, Comprising: A charged particle source; An extraction electrode that extracts charged particles from the charged particle source and allows a part of the charged particles to pass through while shielding another part of the charged particles; and A continuous heat transfer structure, which is a continuous heat transfer structure different from the extraction electrode, is outside the extraction electrode, and contacts at least two surfaces of the extraction electrode including a plane perpendicular to the traveling direction of the charged particles extracted from the charged particle source and a plane parallel to the traveling direction with respect to the traveling direction of the charged particles.

2. The charged particle gun according to claim 1, wherein The extraction electrode has a passing portion through which the part of the charged particles passes, The heat transfer structure contacts the surface of the extraction electrode on the side opposite to the charged particle source, The heat transfer structure has an opening portion that includes the entire passing portion when viewed from the optical axis direction.

3. The charged particle gun according to claim 1 or 2, wherein The charged particle gun further comprises: A conductive member for applying a voltage to the extraction electrode; and An adjustment mechanism for adjusting the positional relationship between the extraction electrode and the conductive member, The adjustment mechanism adjusts and fixes the positional relationship between the extraction electrode and the conductive member in a state where the extraction electrode and the conductive member are in contact with each other and the central axis of the extraction electrode, the central axis of the conductive member, and the central axis of the charged particle source are aligned.

4. The charged particle gun according to claim 1, wherein The extraction electrode or the heat transfer structure has fins on its outer periphery.

5. The charged particle gun according to claim 1, wherein The heat transfer structure uses gold, silver, copper, or aluminum as the base material.

6. The charged particle gun according to claim 1, wherein In the heat transfer structure, the contact surface with the extraction electrode includes indium, silver, molybdenum, hafnium, aluminum, nickel, tungsten, gold, or copper.

7. The charged particle gun according to claim 1, wherein In the heat transfer structure, at least a part of the surface that does not contact the extraction electrode includes a metal with an emissivity of 0.1 or more.

8. The charged particle gun according to claim 1 or 2, wherein The heat transfer structure uses a material with a specific heat of 0.6 J / kgK or less and a specific gravity of 5 g / cm 3 or less as the base material, The heat transfer structure is covered with a material having a thermal conductivity of 10 W / mK or more.

9. The charged particle gun according to claim 1, wherein The charged particle gun further comprises: A conductive member for applying a voltage to the extraction electrode; and A fixing member for fixing the extraction electrode and the conductive member to each other, The fixing member includes the heat transfer structure, The heat transfer structure contacts the extraction electrode and includes a metal with a thermal conductivity of 10 W / mK or more.

10. The charged particle gun according to claim 1, wherein The charged particle gun further comprises an adjustment electrode, The adjustment electrode can adjust the amount of charged particles released from the charged particle source by adjusting the electric field strength around the front end of the charged particle source.

11. The charged particle gun according to claim 1, wherein The charged particle gun further includes a conductive member for applying a voltage to the extraction electrode, and the heat transfer structure is also in contact with the conductive member in a plane parallel to the optical axis direction.

12. The charged particle gun according to claim 1, wherein: the heat transfer structure is a heat transfer structure body obtained by combining a plurality of components.

13. The charged particle gun according to claim 1, wherein: a surface treatment is performed on the heat transfer structure.

14. A charged particle beam system, characterized in that, Comprising: the charged particle gun according to claim 1; and a computer system for controlling the charged particle gun.

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