Centering mechanism and scanning electron microscope having the same

Abstract

The application relates to a centering mechanism and a scanning electron microscope provided with the same, which is used for centering and calibrating an electron beam in the scanning electron microscope, and comprises an electron gun cavity and a mounting cavity. A first through hole is formed in the electron gun cavity, a first boss is arranged on the side of the electron gun cavity facing the mounting cavity, and the first boss is annular. A mounting groove is formed in the side of the mounting cavity facing the electron gun cavity, a distance is arranged between the outer side wall of the first boss and the inner side wall of the mounting groove, a mounting hole suitable for mounting a component aligned with the electron beam is formed in the groove bottom of the mounting groove, a first adjusting piece is movably arranged on the side wall of the mounting cavity where the mounting groove is formed, and the first adjusting piece penetrates the side wall of the mounting cavity. A plurality of first adjusting pieces are arranged in a spaced distribution along the circumference of the mounting groove. The centering and adjusting of the electron beam are realized, the scanning electron microscope reaches the best state, and the influence of the optical axis deviation on the resolution and the key parameter indexes of the machine table is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductors, and in particular to a centering mechanism and a scanning electron microscope having the same. BACKGROUND

[0002] With the development of semiconductor technology and the progress of process technology, integrated circuit line width is increasingly developed to be fine, and higher and more difficult requirements are put forward for the production process technology of the circuit. Not only sub-micron lines are etched, but also line defects are controlled within a certain range to ensure the function and yield of the chip. Research shows that when the size of the defect is more than one-third of the feature line width, it becomes a fatal defect that will cause device failure. As the size of the device is continuously reduced, the size of the fatal defect also becomes smaller and smaller, and the detection of defects becomes more difficult. Optical detection equipment cannot meet the needs, and electron beam detection equipment overcomes the limitation of optical wavelength, improves the resolution to the nanometer field, and can detect extremely small defects.

[0003] The core of the electron beam detection equipment is a scanning electron microscope. In the scanning electron microscope, the centering of the electron beam directly affects the performance of the electron microscope, and the ideal working state cannot be achieved. SUMMARY

[0004] Therefore, the present application provides a centering mechanism and a scanning electron microscope having the same, which realizes the centering adjustment of the electron beam. Thus, the optimal state of the scanning electron microscope is achieved, and the influence of the optical axis deviation on the resolution and key parameter indicators of the machine is reduced.

[0005] According to an aspect of the present application, a centering mechanism is provided for installation in a scanning electron microscope to center and calibrate an electron beam in the scanning electron microscope. The centering mechanism includes an electron gun cavity and a mounting cavity connected in sequence and detachably.

[0006] A first through hole is formed in the electron gun cavity, and a first boss is arranged on the side of the electron gun cavity facing the mounting cavity. The first boss has an annular structure arranged around the first through hole.

[0007] A mounting groove is formed in the side of the mounting cavity facing the electron gun cavity. The first boss is placed inside the mounting groove, and a distance is provided between the outer side wall of the first boss and the inner side wall of the mounting groove.

[0008] A mounting hole suitable for mounting a component aligned with the electron beam is formed in the groove bottom of the mounting groove, and the mounting hole penetrates the mounting cavity.

[0009] A first adjusting member is movably arranged on the side wall of the installation cavity at the position where the installation groove is arranged, the first adjusting member is arranged through the side wall of the installation cavity, and the first adjusting member is used for pushing the first boss to move in the installation groove.

[0010] A plurality of first adjusting members are arranged in a circumferential direction of the installation groove.

[0011] In a possible implementation, the first boss comprises a bevel part, a side wall of the bevel part is arranged in a bevel shape, the bevel part is arranged adjacent to a groove bottom of the installation groove, and a distance between the bevel part and an inner side wall of the installation groove gradually decreases in a first direction.

[0012] The first direction is a direction in which the electron gun cavity points to the installation cavity.

[0013] The plurality of first adjusting members are all in abutment with the bevel part.

[0014] In a possible implementation, the first adjusting member is in a rod shape, and an outer thread is arranged on a rod body of the first adjusting member.

[0015] The side wall of the installation cavity at the position where the installation groove is arranged is provided with a first inner thread hole, the number of the first inner thread holes is the same as the number of the first adjusting members, and the first adjusting members are threadedly connected with the first inner thread holes one by one.

[0016] In a possible implementation, the first boss further comprises a connecting part, the connecting part is arranged in an annular shape, the connecting part is arranged in a circumferential direction of the first through hole, and an outer chamfer is arranged on a bottom end face of the connecting part.

[0017] The bevel part is fixed on one side of the bottom end face of the connecting part, and a top end face of the bevel part is matched with the bottom end face of the connecting part.

[0018] The bottom of the connecting part is a side of the connecting part adjacent to the groove bottom of the installation groove.

[0019] In a possible implementation, a first sealing ring is further included.

[0020] A first sealing groove is arranged at the groove bottom of the installation groove, the first sealing groove is arranged in an annular shape, the first sealing groove is arranged opposite to the first boss, and the first sealing groove is arranged in a circumferential direction of the first through hole.

[0021] The first sealing ring is arranged in the first sealing groove, and is used for sealing the electron gun cavity and the installation cavity.

[0022] In a possible implementation, a gap is arranged between the side of the first boss facing the bottom of the mounting groove and the bottom of the mounting groove.

[0023] The first sealing ring is in abutment with the first boss.

[0024] In a possible implementation, an objective lens cavity is detachably mounted on the side of the mounting cavity away from the electron gun cavity;

[0025] A second through hole coaxially arranged with the first through hole is arranged on the objective lens cavity, and a placement groove is arranged on the end of the objective lens cavity facing the mounting cavity;

[0026] A second boss is arranged on the side of the mounting cavity facing the placement groove, the second boss is placed in the placement groove, and a distance is arranged between the outer side wall of the second boss and the inner side wall of the placement groove.

[0027] A second adjusting member is movably mounted on the side wall of the placement groove of the objective lens cavity, a plurality of second adjusting members are arranged, and the plurality of second adjusting members are distributed along the circumference of the placement groove;

[0028] The plurality of second adjusting members are arranged through the side wall of the placement groove, and are used to push the second boss to move in the placement groove.

[0029] In a possible implementation, a second sealing ring is further included.

[0030] A second sealing groove is arranged at the bottom of the placement groove, the second sealing groove is arranged in a ring shape, the second sealing groove is arranged opposite to the second boss, and the second sealing groove is arranged circumferentially around the second through hole;

[0031] The second sealing ring is mounted in the second sealing groove, and is used to seal the mounting cavity and the objective lens cavity.

[0032] In a possible implementation, the mounting hole includes a first mounting hole, a second mounting hole, and a third mounting hole;

[0033] The first mounting hole, the second mounting hole, and the third mounting hole are arranged in sequence along the circumferential direction of the mounting cavity.

[0034] The aperture of the first mounting hole and the aperture of the third mounting hole are both larger than the aperture of the second mounting hole.

[0035] The first mounting hole, the second mounting hole, and the third mounting hole are coaxially arranged.

[0036] In a possible implementation, a gap is arranged between the side of the first boss facing the groove bottom of the mounting groove and the groove bottom of the mounting groove.

[0037] The first sealing ring is in abutment with the first boss.

[0038] According to another aspect of the present application, a scanning electron microscope is provided, comprising the centering mechanism of any one of the above.

[0039] The centering mechanism of the embodiment of the present application is divided into an electron gun cavity and a mounting cavity, wherein the mounting cavity is detachably mounted at the bottom of the electron gun cavity, and the mounting cavity is provided with a mounting hole for mounting a detector. After the electron gun cavity and the mounting cavity are assembled, at this time, the first boss at the bottom of the electron gun cavity is located in the mounting groove. When the part mounted on the mounting hole and aligned with the electron beam is centered with the electron beam, the plurality of first adjusting members on the mounting cavity are adjusted, and the length of the first adjusting member extending into the mounting groove changes, so that the movement of the first adjusting member pushes the first boss to move in the mounting groove, thereby driving the entire electron gun cavity to move and adjust. Since the first adjusting member is arranged in multiple directions along the circumference of the mounting groove, the position of the electron gun cavity can be adjusted in each direction until the part mounted on the mounting hole and aligned with the electron beam is centered with the electron beam. In summary, the centering mechanism of the embodiment of the present application adjusts the first adjusting member to drive the electron gun cavity to fine-tune in the mounting groove, so that the electric field center of the part mounted on the mounting hole and aligned with the electron beam coincides with the center of the electron beam, thereby realizing the centering adjustment of the electron beam. Thus, the best state of the scanning electron microscope is achieved, and the influence of the optical axis deviation on the resolution and the key parameter index of the machine is reduced.

[0040] Other features and aspects of the present application will become apparent from the following detailed description of exemplary embodiments with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0041] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the present application and serve to explain the principles of the present application.

[0042] Figure 1 A main structure diagram of the centering mechanism of the embodiment of the present application is shown;

[0043] Figure 2 A sectional view of the centering mechanism of the embodiment of the present application is shown;

[0044] Figure 3 A partial enlarged view of an installation diagram of the electron gun cavity and the mounting cavity of the centering mechanism of the embodiment of the present application is shown;

[0045] Figure 4A partial enlarged view of an installation view of the installation cavity and the objective lens cavity of the centering mechanism of the embodiment of the present application is shown. DETAILED DESCRIPTION

[0046] Various exemplary embodiments, features and aspects of the present application will be described in detail below with reference to the accompanying drawings. The same reference numbers in the drawings represent the same elements or similar elements. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0047] It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like indicate relative or positional relationships based on the orientation or position shown in the drawings, and are used only for convenience of description or simplification of description, and do not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be construed as limiting the present application.

[0048] In addition, the terms "first", "second", are used only for descriptive purposes and should not be construed as indicating or implying relative importance or an indicated number of technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0049] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations.

[0050] In addition, in order to better illustrate the present application, numerous specific details are given in the following detailed description. Those skilled in the art will understand that the present application can also be implemented without some of the specific details. In some examples, methods, means, elements and circuits well known to those skilled in the art are not described in detail in order to highlight the main idea of the present application.

[0051] Figure 1 A main structure view of the centering mechanism of the embodiment of the present application is shown. Figure 2 A sectional view of the centering mechanism of the embodiment of the present application is shown. Figure 3 A partial enlarged view of an installation view of the electron gun cavity 100 and the installation cavity 200 of the centering mechanism of the embodiment of the present application is shown. Figure 4 A partial enlarged view of an installation view of the installation cavity 200 and the objective lens cavity 600 of the centering mechanism of the embodiment of the present application is shown. As shown in the figure, the installation cavity 200 and the objective lens cavity 600 are arranged in parallel.Figure 1 、 Figure 2 、 Figure 3 or Figure 4 As shown in the figure, the centering mechanism is used for installing in a scanning electron microscope, and the centering mechanism is used for centering calibration of an electron beam in the scanning electron microscope, and the centering mechanism comprises: an electron gun cavity 100 and a mounting cavity 200 which are sequentially detachably connected. The electron gun cavity 100 is provided with a first through hole, and the side of the electron gun cavity 100 facing the mounting cavity 200 is provided with a first boss 110, and the first boss 110 is in an annular structure arranged around the first through hole. The side of the mounting cavity 200 facing the electron gun cavity 100 is provided with a mounting groove, and the first boss 110 is placed in the mounting groove, and a distance is provided between the outer side wall of the first boss 110 and the inner side wall of the mounting groove. The bottom of the mounting groove is provided with a mounting hole for mounting a component aligned with the electron beam, and the mounting hole penetrates through the mounting cavity 200. The side wall of the mounting cavity 200 at the position where the mounting groove is arranged is movably provided with a first adjusting piece 300, the first adjusting piece 300 penetrates through the side wall of the mounting cavity 200, the first adjusting piece 300 is used for pushing the first boss 110 to move in the mounting groove, and a plurality of first adjusting pieces 300 are provided, and the plurality of first adjusting pieces 300 are distributed along the circumference of the mounting groove.

[0052] The centering mechanism of the embodiment of the present application is divided into two parts of the electron gun cavity 100 and the mounting cavity 200, wherein the mounting cavity 200 is detachably mounted at the bottom of the electron gun cavity 100, and the mounting cavity 200 is provided with a mounting hole for mounting a detector 400. After the electron gun cavity 100 and the mounting cavity 200 are assembled, at this time, the first boss 110 at the bottom of the electron gun cavity 100 is located in the mounting groove. When the component mounted on the mounting hole and aligned with the electron beam is centered with the electron beam, the plurality of first adjusting pieces 300 on the mounting cavity 200 are adjusted, and the length of the first adjusting piece 300 extending into the mounting groove changes, so that the movement of the first adjusting piece 300 pushes the first boss 110 to move in the mounting groove, thereby driving the entire electron gun cavity 100 to move and adjust. Since a plurality of first adjusting pieces 300 are arranged along the circumference of the mounting groove, the first adjusting piece 300 can adjust the position of the electron gun cavity 100 in each direction until the component mounted on the mounting hole of the mounting cavity 200 and aligned with the electron beam is centered with the electron beam. In summary, the centering mechanism of the embodiment of the present application adjusts the first adjusting piece 300 to drive the electron gun cavity 100 to fine-tune in the mounting groove, so that the electric field center of the component mounted on the mounting hole and aligned with the electron beam coincides with the center of the electron beam, thereby realizing the centering adjustment of the electron beam, and thus achieving the best state of the scanning electron microscope and reducing the influence of the optical axis deviation on the resolution and key parameter indicators of the machine.

[0053] It should be pointed out here that the electron beam alignment component installed on the mounting hole is coaxially arranged with the mounting hole. The electron beam alignment component installed on the mounting hole can be an anastigmat in the scanning electron microscope, or can be the detector 400. In the embodiments of the present application, the detector 400 is taken as an example for description.

[0054] That is, the centering mechanism of the embodiments of the present application can be used to center and calibrate the optical axis center of the electron beam in the scanning electron microscope and the center of the anastigmat, and can also be used to center and calibrate the optical axis center of the electron beam in the scanning electron microscope and the center of the detector 400. It should be pointed out here that in a possible implementation, the electron gun cavity 100 is cylindrical, and the axis of the first through hole is coaxially arranged with the axis of the electron gun cavity 100. Thus, the centering of the electron beam installed on the mounting hole is further facilitated, and the structure of the embodiments of the present application is optimized.

[0055] It should be pointed out here that in a possible implementation, the mounting cavity 200 is cylindrical, and after the mounting cavity 200 and the electron gun cavity 100 are assembled, the outer side wall of the mounting cavity 200 is flush with the outer side wall of the electron gun cavity 100. The mounting slot is circular slot-shaped, and the axis of the mounting slot is coaxially arranged with the axis of the first through hole, and the axis of the mounting hole is coaxially arranged with the axis of the first through hole. Thus, the electron beam installed on the mounting hole is more easily centered, and the centering is more accurate.

[0056] It should be pointed out here that in a possible implementation, the top end face of the mounting cavity 200 is parallelly arranged with the bottom end face of the electron gun cavity 100, and after the electron gun cavity 100 and the mounting cavity 200 are assembled, the bottom flat end face of the electron gun cavity 100 is abuttingly arranged with the top end face of the mounting cavity 200. The mounting hole includes the first hole and the second hole which are sequentially arranged in a stepped hole shape, wherein the first hole is adjacent to the electron gun cavity 100, and the hole bottom end face of the first hole is parallelly arranged with the top end face of the mounting cavity 200. Thus, the parallelism of the contact surface of the electron gun cavity 100 and the mounting cavity 200 is improved, the parallelism of the contact surface of the mounting cavity 200 and the detector 400 is also improved, the form and position tolerances are reduced, the optical axis deviation is prevented, and the installation error is reduced.

[0057] As Figure 1 , Figure 2 or Figure 4As shown, in a possible implementation, the first boss 110 includes a beveled portion 112, a side wall of the beveled portion 112 is arranged in a bevel, the beveled portion 112 is arranged adjacent to the bottom of the mounting groove, and a distance between the beveled portion 112 and the inner side wall of the mounting groove gradually decreases along a first direction. The first direction is a direction in which the electron gun cavity points to the mounting cavity 200, and each of the first adjusting members 300 abuts against the beveled portion 112. Since the first adjusting member 300 abuts against the first boss 110, and the force receiving portion of the first boss 110 is the beveled portion 112, the first adjusting member 300 exerts a downward component force on the beveled portion 112 when in action, so that the beveled portion 112 does not tilt when in motion, and the sealing effect is ensured.

[0058] Furthermore, in a possible implementation, the first boss 110 further includes a connecting portion 111, the connecting portion 111 is arranged in a ring shape, the connecting portion 111 is arranged circumferentially around the first through hole, and an outer chamfer is arranged on a bottom end face of the connecting portion 111. The beveled portion 112 is fixed on one side of the bottom end face of the connecting portion 111, and a top end face of the beveled portion 112 matches the bottom end face of the connecting portion 111. The bottom of the connecting portion 111 is a side of the connecting portion 111 adjacent to the bottom of the mounting groove. In this way, the structure of the first boss 110 is matched with the structure of the first adjusting member 300, and the tilting of the first boss 110 when in motion is further prevented.

[0059] It should be noted that, in a possible implementation, the connecting portion 111, the beveled portion 112, and the electron gun cavity 100 can be integrally formed. In this way, the manufacturing of the electron gun cavity 100 is facilitated.

[0060] In a possible implementation, a first sealing ring 500 is further included, and a first sealing groove is arranged at the bottom of the mounting groove, the first sealing groove is arranged in a ring shape, and the first sealing groove is arranged opposite to the first boss 110 and circumferentially around the first through hole. The first sealing ring 500 is arranged in the first sealing groove, and the first sealing ring 500 is used to seal the electron gun cavity 100 and the mounting cavity 200. In this way, the sealing performance of the electron gun cavity 100 and the mounting cavity 200 is improved.

[0061] In a possible implementation, the first adjusting rod member is in a rod shape, and an outer thread is arranged on the rod body of the first adjusting member 300. A first inner thread hole is arranged on the side wall of the mounting groove of the mounting cavity 200, the number of the first inner thread holes is the same as the number of the first adjusting members 300, and the first adjusting members 300 are threadedly connected to the first inner thread holes one by one. In this way, the position of the electron gun cavity 100 can be adjusted by rotating the first adjusting member 300, and the centering of the component aligned with the electron beam and the electron beam is facilitated.

[0062] As shown in FIG. 1, the electron gun cavity 100 is arranged in the mounting cavity 200, and the first adjusting member 300 is arranged in the mounting cavity 200. Figure 1 ,Figure 2 、 Figure 3 or Figure 4 Further, in a possible implementation, the objective lens cavity 600 is detachably mounted on the side of the mounting cavity 200 away from the electron gun cavity 100. The objective lens cavity 600 is provided with a second through hole coaxially arranged with the first through hole, and an end of the objective lens cavity 600 facing the mounting cavity 200 is provided with a placement groove. The side of the mounting cavity 200 facing the placement groove is provided with a second boss 210, the second boss 210 is placed in the placement groove, and a distance is provided between the outer side wall of the second boss 210 and the inner side wall of the placement groove. The side wall of the objective lens cavity 600 at the placement groove is movably provided with a second adjusting member 700, and the second adjusting member 700 is provided in plurality, and the plurality of second adjusting members 700 are distributed along the circumference of the placement groove. The plurality of second adjusting members 700 are arranged through the side wall of the placement groove, and the end of the plurality of second adjusting members 700 facing the second boss 210 is connected with the second boss 210, and is used to push the mounting cavity 200 to move in the placement groove. Through the above structure, the second adjusting member 700 is adjusted to drive the second boss 210 to move in the placement groove, so that the position of the mounting cavity 200 can be adjusted, and the components on the mounting cavity 200 aligned with the electron beam are centered with the objective lens.

[0063] Here, it should be pointed out that, in a possible implementation, the second through hole is coaxially arranged with the first through hole, the objective lens cavity 600 is cylindrical, the outer wall of the objective lens cavity 600 is flush with the outer wall of the mounting cavity 200, and the aperture of the second through hole is the same as the aperture of the first through hole. Thus, the structure of the embodiment of the application is further optimized.

[0064] Here, it should be further pointed out that, in a possible implementation, the side wall of the second boss 210 is parallelly arranged with the side wall of the first boss 110. The top end face of the objective lens cavity 600 is parallelly arranged with the bottom end face of the mounting cavity 200, and after the objective lens cavity 600 and the mounting cavity 200 are assembled, the top end face of the objective lens cavity 600 is coincidentally arranged with the bottom end face of the mounting cavity 200. The top end face of the objective lens cavity 600 is parallelly arranged with the groove bottom of the mounting groove of the mounting cavity 200. Thus, the form and position tolerances are further eliminated.

[0065] It should be pointed out here that, in a possible implementation, a plurality of first bolt holes are formed on the electron gun cavity 100, the plurality of first bolt holes are arranged through the electron gun cavity 100, and the plurality of first bolt holes are distributed around the axis of the electron gun cavity 100. The plurality of first bolt holes are arranged adjacent to the edge position of the electron gun cavity 100. A plurality of second bolt holes are formed on the mounting cavity 200, the number of second bolt holes is the same as the number of first bolt holes, and the second bolt holes are arranged one by one corresponding to the first bolt holes. The second bolt holes are arranged through the mounting cavity 200. A plurality of third bolt holes are formed on the objective lens cavity 600, the number of third bolt holes is the same as the number of first bolt holes, and the third bolt holes are arranged one by one corresponding to the first bolt holes. The electron cavity, the mounting cavity 200 and the objective lens cavity 600 are connected by bolts (the bolts are screwed with the first bolt holes, the second bolt holes and the third bolt holes in turn). Thus, after adjusting the electron gun cavity 100 and the mounting cavity 200, the bolts can be locked to prevent movement and ensure that the relative position does not change.

[0066] Further, a second sealing ring 800 is also included, a second sealing groove is formed at the bottom of the placement groove, the second sealing groove is arranged in a ring shape, the second sealing groove is arranged opposite to the second boss 210, and the second sealing groove is arranged circumferentially around the second through hole. The second sealing ring 800 is installed in the second sealing groove to seal the mounting cavity 200 and the objective lens cavity 600.

[0067] In a possible implementation method, the mounting hole includes a first mounting hole, a second mounting hole and a third mounting hole, wherein the first mounting hole, the second mounting hole and the third mounting hole are arranged in sequence along the circumferential direction of the mounting cavity 200. The hole diameter of the first mounting hole and the hole diameter of the third mounting hole are both greater than the hole diameter of the second mounting hole, and the first mounting hole, the second mounting hole and the third mounting hole are coaxially arranged with the detector 400. Thus, the centering of the detector 400 is more accurate.

[0068] Further, in a possible implementation, after the electron gun cavity 100 and the mounting cavity 200 are assembled, a gap is provided between the first boss 110 and the bottom of the mounting groove, and the first sealing ring 500 abuts against the first boss 110. Thus, without affecting the sealing effect, the first boss 110 and the bottom of the mounting groove are avoided as the contact surface, the tolerance uncertainty of the sealing ring itself is avoided, the optical axis offset is further placed, and the installation error is reduced.

[0069] It should be noted here that when the component aligning with the electron beam is the detector 400, a mounting plate 900 is also included, wherein the detector 400 has a central hole. The detector 400 is fixedly mounted on the mounting plate 900, and bolt holes are provided at the edge of the mounting plate 900 for bolting to the mounting cavity 200, so that the mounting plate 900 is located inside the first mounting hole. After the mounting plate 900 is bolted to the mounting cavity 200, the detector 400 is positioned on the surface of the mounting plate 900 facing the second mounting hole. The mounting plate 900 has a central hole, and the central hole on the mounting plate 900 is coaxially arranged with the central hole on the detector 400.

[0070] In one possible implementation, the second boss 210 has a gap between itself and the placement groove on the side facing the groove, and the second sealing ring 800 abuts against the second boss 210. The structure of the second protrusion is the same as that of the first boss 110. This prevents the second boss 210 (and the objective lens cavity 600) from tilting up during movement, thus ensuring sealing performance.

[0071] like Figure 1 As shown, based on the centering mechanism described in any of the above claims, this disclosure also provides a scanning electron microscope (SEM). The SEM of this disclosure includes the centering mechanism described in any of the above claims. By installing the centering mechanism described in any of the preceding claims on the SEM, the centering adjustment of the electron beam is facilitated. The electron gun cavity 100 can be equipped with an electron gun and a condenser lens, and the objective lens cavity 600 can be equipped with an objective aperture, a detector 400, an objective lens, and a deflector.

[0072] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A centering mechanism characterized in that, A device for installing in a scanning electron microscope, for centering calibration of an electron beam in the scanning electron microscope, comprising an electron gun cavity and a mounting cavity connected in turn detachably; A first through hole is formed on the electron gun cavity, and a first boss is arranged on the side of the electron gun cavity facing the mounting cavity, and the first boss is in an annular structure arranged around the first through hole; A mounting groove is formed on the side of the mounting cavity facing the electron gun cavity, the first boss is placed inside the mounting groove, and a distance is provided between the outer sidewall of the first boss and the inner sidewall of the mounting groove; An installation hole suitable for installing a component aligned with the electron beam is formed at the groove bottom of the mounting groove, the installation hole penetrates through the mounting cavity, and the installation hole is coaxially arranged with the detector; A first adjusting member is movably installed on the sidewall of the mounting cavity where the mounting groove is formed, the first adjusting member penetrates through the sidewall of the mounting cavity, and the first adjusting member is used to push the first boss to move in the mounting groove; A plurality of first adjusting members are distributed along the circumference of the mounting groove; Further comprising an objective lens cavity, which is detachably installed on the side of the mounting cavity away from the electron gun cavity; A second through hole coaxially arranged with the first through hole is formed on the objective lens cavity, and a placement groove is formed on the end of the objective lens cavity facing the mounting cavity; A second boss is arranged on the side of the mounting cavity facing the placement groove, and the second boss is placed in the placement groove, and a distance is provided between the outer sidewall of the second boss and the inner sidewall of the placement groove; A second adjusting member is movably installed on the sidewall of the objective lens cavity where the placement groove is formed, and a plurality of second adjusting members are distributed along the circumference of the placement groove; A plurality of second adjusting members penetrate through the sidewall of the placement groove and are used to push the second boss to move in the placement groove; The sidewall of the second boss is arranged in parallel with the sidewall of the first boss; the top end surface of the objective lens cavity is arranged in parallel with the bottom end surface of the mounting cavity, and after the objective lens cavity and the mounting cavity are assembled, the top end surface of the objective lens cavity is arranged in coincidence with the bottom end surface of the mounting cavity; the top end surface of the objective lens cavity is arranged in parallel with the groove bottom of the mounting groove of the mounting cavity.

2. The centering mechanism of claim 1, wherein, The first boss comprises a bevel part, the sidewall of the bevel part is arranged in a bevel, the bevel part is arranged adjacent to the groove bottom of the mounting groove, and the distance between the bevel part and the inner sidewall of the mounting groove gradually decreases along a first direction; The first direction is the direction in which the electron gun cavity points to the mounting cavity; A plurality of first adjusting members are in abutment with the bevel part.

3. The centering mechanism of claim 1, wherein, The first adjusting member is in the shape of a rod, and an external thread is formed on the rod body of the first adjusting member; A first internal thread hole is formed on the sidewall of the mounting cavity where the mounting groove is formed, the number of the first internal thread holes is the same as the number of the first adjusting members, and the first adjusting members are screw-connected with the first internal thread holes one by one.

4. The centering mechanism of claim 2, wherein, The first boss further comprises a connecting portion, which is annularly arranged and circumferentially arranged around the first through hole, and an outer chamfer is arranged on the bottom end face of the connecting portion; The inclined surface portion is fixed on one side of the bottom end face of the connecting portion, and the top end face of the inclined surface portion matches the bottom end face of the connecting portion; The bottom of the connecting portion is adjacent to one side of the groove bottom of the mounting groove.

5. The centering mechanism of claim 1, wherein, Further comprising a first sealing ring; A first sealing groove is arranged at the groove bottom of the mounting groove, and the first sealing groove is annularly arranged, oppositely arranged with the first boss, and circumferentially arranged around the first through hole; The first sealing ring is installed in the first sealing groove to seal the electron gun cavity and the mounting cavity.

6. The centering mechanism of claim 5, wherein, A gap is arranged between the side of the first boss facing the groove bottom of the mounting groove and the groove bottom of the mounting groove; The first sealing ring abuts against the first boss.

7. The centering mechanism of claim 1, wherein, Further comprising a second sealing ring; A second sealing groove is arranged at the groove bottom of the placing groove, and the second sealing groove is annularly arranged, oppositely arranged with the second boss, and circumferentially arranged around the second through hole; The second sealing ring is installed in the second sealing groove to seal the mounting cavity and the objective lens cavity.

8. The centering mechanism according to any one of claims 1 to 7, characterized in that The mounting hole comprises a first mounting hole, a second mounting hole and a third mounting hole; The first mounting hole, the second mounting hole and the third mounting hole are sequentially arranged along the circumferential direction of the mounting cavity; The aperture of the first mounting hole and the aperture of the third mounting hole are both larger than the aperture of the second mounting hole; The first mounting hole, the second mounting hole and the third mounting hole are coaxially arranged.

9. The centering mechanism of claim 5, wherein, A gap is arranged between the side of the first boss facing the groove bottom of the mounting groove and the groove bottom of the mounting groove; The first sealing ring abuts against the first boss.

10. A scanning electron microscope characterized by, The centering mechanism of any one of claims 1 to 9.

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