CN109300760B - Electron beam control device and method, electron beam imaging module, and electron beam inspection apparatus - Google Patents
Electron beam control device and method, electron beam imaging module, and electron beam inspection apparatus Download PDFInfo
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- H01J37/26—Electron or ion microscopes; Electron or ion diffraction tubes
- H01J37/28—Electron or ion microscopes; Electron or ion diffraction tubes with scanning beams
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- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
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- G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
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- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/02—Details
- H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement, ion-optical arrangement
- H01J37/09—Diaphragms; Shields associated with electron or ion-optical arrangements; Compensation of disturbing fields
Abstract
The present disclosure provides an electron beam control device and method, an electron beam imaging module, an electron beam inspection apparatus for adjusting a size of an incident electron beam. The provided electron beam control device for adjusting the size of an incident electron beam includes an aperture member provided with a plurality of aperture holes arranged at intervals, the position of each of the plurality of aperture holes on the aperture member being determined to correspond to a plurality of different half-aperture angles of the incident electron beam and to different sizes of the electron beam, and the size of each aperture hole being determined to be sufficient to pass the electron beam provided with the corresponding size, whereby the size of the incident electron beam can be adjusted by shifting the electron beam to a selected aperture hole of the plurality of aperture holes.
Description
Technical Field
The present disclosure relates to the field of image processing, and in particular, to an electron beam control apparatus and method, an electron beam imaging module, and an electron beam inspection apparatus for image acquisition.
Background
In recent years, electron beam inspection equipment for inspecting fine patterns and measuring critical dimensions on semiconductor wafers or reticles by using electron beam technology in vacuum has become widely used, including but not limited to: critical dimension measuring equipment for critical dimension measurement of patterns, such as a scanning electron microscope (CD-SEM), Review equipment such as a Review scanning electron microscope (Review SEM) that performs Review in a precise observation manner with respect to defects that have been detected by an electron beam inspection apparatus, pattern defect inspection equipment that predicts a region where the incidence of defects is high using a computer, and the like. The above-mentioned apparatus not only needs to be miniaturized in size of the electron beam to perform accurate detection and measurement, but also needs to further increase the detection speed.
However, the conventional method for increasing the inspection speed of the electron beam inspection apparatus generally employs a large pixel size and a large beam current to achieve high-speed scanning of the inspected area, but the method cannot be used to inspect fine defects. Moreover, the functions of defect detection, review and critical dimension measurement are usually performed by a plurality of separate devices, and a single device with integrated functions cannot be realized.
In order to realize a single device integrating functions of defect detection, review and critical dimension measurement, the size of the electron beam and the beam current need to be switched as fast as possible, so as to keep the electron beam switched between smaller sizes and faster scanning speed and switching speed.
Disclosure of Invention
To solve at least one aspect of the above problems and disadvantages in the related art, the present invention provides an electron beam control apparatus and method, an electron beam imaging module, and an electron beam inspection apparatus. The technical scheme is as follows:
to achieve the above object, according to a first aspect of the present disclosure, there is provided an electron beam control apparatus for adjusting a size of an incident electron beam, comprising an aperture member provided with a plurality of aperture holes arranged at intervals, wherein a position of each of the plurality of aperture holes on the aperture member is determined to correspond to a plurality of different half-aperture angles of the incident electron beam and to different sizes of the electron beam, and a size of each aperture hole is determined to be sufficient to pass the electron beam having the corresponding size, whereby the size of the incident electron beam can be adjusted by shifting the electron beam to a selected aperture hole of the plurality of aperture holes.
According to an embodiment of the disclosure, one of the incident electron beam and the diaphragm member is movable such that the electron beam is displaced to the selected diaphragm aperture, and the selected diaphragm aperture is selected based on a size of the electron beam determined according to a desired field size.
According to the embodiment of the disclosure, the plurality of diaphragm holes are distributed on the diaphragm member in a two-dimensional pattern in a surrounding arrangement or an array arrangement, and in the two-dimensional pattern, the electron beam can be directly shifted between any two diaphragm holes in a straight or smoothly curved path without passing through other diaphragm holes.
According to an embodiment of the present disclosure, the plurality of diaphragm holes in a two-dimensional pattern includes: a first diaphragm aperture, a position of which is determined based on a minimum size of the electron beam, and a size of which is determined to be sufficient to pass the electron beam having the minimum size; and further diaphragm apertures distributed around the first diaphragm aperture.
According to an embodiment of the present disclosure, the first diaphragm aperture is arranged at a center of the diaphragm member.
According to an embodiment of the disclosure, the other diaphragm apertures are arranged in one or more rings distributed around the first diaphragm aperture in a two-dimensional pattern in a surrounding arrangement.
According to an embodiment of the present disclosure, the electron beam control apparatus further includes: a displacement member configured to move one of the incident electron beam and the aperture member, and a control circuit configured in electrical communication with the displacement member to control the displacement member such that the electron beam passes through a selected aperture of the plurality of aperture apertures.
According to an embodiment of the disclosure, the control circuit further comprises an input device configured for inputting a pixel size of the desired field of view, and further to determine the selected diaphragm aperture according to the inputted pixel size.
According to an embodiment of the present disclosure, the diaphragm member is configured as a movable multi-aperture diaphragm plate movably arranged on a plane perpendicular to an optical axis upon incidence of the electron beam, so that the electron beam projected thereon passes through a selected diaphragm aperture of the plurality of diaphragm apertures.
According to an embodiment of the present disclosure, the displacement member includes a displacement device adapted to move the movable multi-aperture diaphragm plate in a vacuum and/or ultra-clean environment.
According to an embodiment of the present disclosure, the displacement device includes: a driver and a motion feedthrough. The driver comprises at least one of a pneumatic driver, a manual driving device and a motor, the driver being arranged outside the vacuum and/or ultra-clean environment and configured to generate a driving action. The motion feed-in is arranged in a kinematic coupling between the driver and the movable multi-aperture diaphragm plate and is configured to transmit and/or convert a driving action output by the driver into an actuating action acting directly on the movable multi-aperture diaphragm plate to displace the movable multi-aperture diaphragm plate, and the actuating action is synchronized with a speed at which the electron beam switches among the plurality of diaphragm apertures.
According to an embodiment of the present disclosure, the displacement device is a piezoelectric displacement device comprising: a drive circuit and a piezoelectric actuator. The drive circuit is disposed in or outside the vacuum and/or ultra-clean environment and is configured to generate a drive electrical signal. The piezoelectric actuator is arranged in the vacuum and/or ultra-clean environment and is arranged in electrical communication with the drive circuit to receive the drive electrical signal and to output an actuation action acting directly on the movable multi-aperture diaphragm plate to displace the movable multi-aperture diaphragm plate, the actuation action being synchronized with a speed at which the electron beam switches among the plurality of diaphragm apertures.
According to an embodiment of the present disclosure, the diaphragm member is configured as a fixed type aperture plate on a plane perpendicular to an optical axis at the time of incidence of the electron beam.
According to an embodiment of the present disclosure, the displacement member further comprises a deflector assembly configured to deflect the electron beam, the deflector assembly comprising: at least one first deflector upstream of the diaphragm member, configured to deviate the optical axis of the electron beam from the optical axis at incidence and to be directed towards the selected diaphragm aperture; and at least one second deflector downstream of said diaphragm member, configured to deflect the electron beam exiting said selected diaphragm aperture such that the optical axis coincides again with the optical axis upon incidence.
According to an embodiment of the present disclosure, the deflector assembly further comprises: at least one third deflector interposed between the first deflector and the aperture member, configured to cause the electron beam deflected by the first deflector to pass through selected ones of the plurality of aperture apertures in a direction substantially parallel to, but not coincident with, the optical axis at incidence; and at least one fourth deflector interposed between the diaphragm member and the second deflector, configured to adjust the electron beam having passed through the diaphragm member toward an optical axis at the time of incidence. Wherein both the first deflector and the third deflector and both the second deflector and the fourth deflector are controlled separately or in linkage.
In addition, according to another aspect of the present disclosure, there is provided an electron beam imaging module configured to project an incident electron beam toward a surface of a sample to be measured to generate an electron beam image, the electron beam imaging module including: an electron beam emission source configured to generate and emit an incident electron beam; controlling means for controlling the electron beam; a scanning deflector disposed symmetrically with respect to an optical axis upon incidence of the electron beam at a downstream of the electron beam control device and configured to deflect the electron beam to scan a surface of a sample to be measured; and an exit electron detector configured to detect an exit electron including at least one of a secondary electron and a backscattered electron generated by the incident electron beam being projected to the sample to be measured.
Further, according to still another aspect of the present disclosure, there is provided an electron beam inspection apparatus including: an electron beam imaging module according to the foregoing; and a displacement platform module comprising the following devices arranged in an overlapping manner: a horizontal displacement platform; a Z-displacement stage configured to change the working distance.
According to the embodiment of the disclosure, the electron beam detection device further comprises a module for analyzing and processing the image generated by at least one of the secondary electron and backscattered electron signals collected by the electron beam imaging module to realize defect detection or critical dimension measurement.
Further, according to still another aspect of the present disclosure, there is provided an electron beam control method for adjusting a size of an incident electron beam using the electron beam control apparatus as described above, the electron beam control method including: determining a desired half field angle of the electron beam based on the desired electron beam size; selecting a diaphragm aperture from a plurality of spaced diaphragm apertures on a diaphragm member in the electron beam control device based on the determined half aperture angle; shifting the electron beam to the selected aperture to adjust the size of the incident electron beam to a desired electron beam size.
According to an embodiment of the present disclosure, in the electron beam control method, a beam current of an electron beam is changed by a change in a size and a half field angle of the electron beam while adjusting the size of the incident electron beam.
Drawings
Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts. The drawings are briefly described as follows:
FIG. 1 shows a schematic graph of the relationship between the electron beam half-angle and the electron beam diameter;
fig. 2 shows a schematic view of an electron beam inspection apparatus according to an embodiment of the present invention, which includes an electron beam imaging module equipped with an electron beam control device for adjusting the size of an incident electron beam;
FIG. 3 is a schematic plan view of an aperture plate for selecting an electron beam half-field angle in the electron beam control apparatus according to FIG. 2;
FIG. 4 is a schematic view showing a positional relationship between a deflector and an aperture plate in the electron beam control apparatus shown in FIG. 2, the aperture holes at different positions on the aperture plate being shown to correspond to different half-field angles of the electron beam, respectively;
fig. 5 is a schematic view illustrating the inspection and size measurement of a specific region using the electron beam inspection apparatus shown in fig. 2.
Detailed Description
The technical solution of the present disclosure will be explained in further detail by way of examples with reference to the accompanying drawings. In the specification, the same or similar reference numerals and letters designate the same or similar components. The following description of the embodiments of the present disclosure with reference to the accompanying drawings is intended to explain the general inventive concept of the present disclosure and should not be construed as limiting the present disclosure.
The drawings are used to illustrate the present disclosure. The dimensions and shapes of the various components in the drawings do not reflect the true proportions of the components of the electron beam control device, the electron beam imaging module, and the electron beam inspection apparatus.
The working principle on which the present disclosure is based is first explained.
Fig. 1 shows a schematic graph of the relationship between the electron beam half-angle and the electron beam diameter.
As is generally known, as shown in fig. 1, a sem has, for example, the following aberrations, including but not limited to the following major aberrations: the geometric aberration caused by the different refractive powers of the paraxial region and the paraxial region of the lens itself to the electron beam is mainly spherical aberration (hereinafter, simply referred to as spherical aberration); imaging errors caused by the dispersion of electron beam kinetic energy due to non-unisex in electron beam wavelength or energy are called chromatic aberration; and diffraction aberrations caused by diffraction effects. Correspondingly, the calculation formula for the electron beam spot diameter d is:
wherein d isdIs a diffraction aberration, dsIs the spherical aberration, i.e. spherical aberration, dcIs due to chromatic aberration caused by longitudinal energy dispersion of electrons in the electron beam.
Further, the above various aberrations are considered.
Wherein the minimum defocus spot radius r due to spherical aberrationsExpressed as:
rs＝(1/4)csα3
(2)
thereby, the spherical aberration dsIs composed of
ds＝(1/2)csα3
(3)
And the color difference dcComprises the following steps:
dc＝ccα|ΔE/E|＝ccα|ΔV/V|
(4)
and the radius r of the bright spot due to the diffraction patterndComprises the following steps:
rd＝0.61λ/αa
(5)
the diffraction aberration is then expressed as:
dd＝2rd＝2*0.61λ/2α＝0.61λ/α
(6)
wherein, csIs the spherical aberration coefficient, ccIs the coefficient of chromatic aberration, λ is the incident electron beamWavelength, αaIs the angle of the aperture of the incident electron beam and α is the half angle of the incident electron beam, i.e., the half angle of the aperture.
And, fig. 3 shows a schematic plan view of an aperture plate for selecting an electron beam half-field angle in the electron beam control apparatus according to fig. 2. As shown in fig. 3 of the present disclosure, for a pass stop a0Is shown as α, corresponding to the half-field angle of the electron beam0。
And, a beam current I of the electron beam0Can be expressed as follows:
I0＝B(πα0d0)2/4 (7)
wherein B is the brightness of the electron beam emission source (e.g., electron gun), and is the initial beam diameter d of the electron beam0，α0The half-field angle of the electron beam corresponding to the diameter of the diaphragm hole with the same size as the initial beam diameter.
Also, with a general electron beam inspection apparatus, the ratio of the pixel size of an image to the beam diameter of an electron beam is generally 1: 2.
Accordingly, the principles of the present disclosure may be inferred based on the above expressions and further describing the specific structure of the present disclosure. Specifically, based on the above expression, in the detection by the electron beam detecting apparatus, it is possible to switch the pixel size while switching different diaphragm apertures on the diaphragm member, and in particular, to realize changes in both the electron beam size (specifically, the beam diameter) and the beam current by switching the diaphragm apertures. In addition, in the detection process, the beam diameter and the beam current of the electron beam can be changed only by switching the diaphragm under the condition of not changing the pixel size.
Referring back to fig. 1, in combination with the above formula, if the distance between the objective lens of the electron beam inspection apparatus and the surface of the sample to be inspected or measured is defined as the working distance, the curve of the beam diameter and the half-aperture angle shown in fig. 1 can be obtained under the condition that the working distance is WD 1; if the working distance is changed to WD2, the spherical aberration coefficient c is usedsAnd a color difference coefficient ccWith a consequent change in the beam size (e.g. beam diameter) relative to the half aperture angleThe series curve also changes differently from the curve corresponding to the working distance WD 1.
An embodiment of the electron beam inspection apparatus having the diaphragm fast switching function will be described in detail below.
Fig. 2 shows a schematic view of an electron beam inspection apparatus according to an embodiment of the present invention, which includes an electron beam imaging module equipped with an electron beam control device for adjusting the size of an incident electron beam; and fig. 3 shows a schematic plan view of an aperture plate for selecting an electron beam half-angle in the electron beam control apparatus according to fig. 2.
The principles of operation are further described below in conjunction with the description of the general manner of operation provided by the present disclosure.
According to the general technical concept of the present disclosure, as shown in fig. 3, in one aspect of the present disclosure, there is provided an electron beam control device 10 for adjusting the size of an incident electron beam EB shown in fig. 2, including an aperture member 9, the aperture member 9 being, for example, in the form of a half-angle aperture plate as shown in the drawing, which is provided with a plurality of aperture holes a arranged at intervalso，A1，Aopt，A2，A3,., the position of each diaphragm aperture of the plurality of diaphragm apertures on the diaphragm member being determined to be at a half opening angle α different from a plurality of different half opening angles of the incident electron beamo，α1，αopt，α2，α3.., and a different size I than the electron beamo，I1，Iopt，I2，I3.., and each diaphragm aperture is sized sufficiently to pass the electron beam of a corresponding size, whereby the size of the incident electron beam can be adjusted by displacement of the electron beam to a selected diaphragm aperture of the plurality of diaphragm apertures.
Referring back to fig. 2 and 3, and considering based on the curves shown in fig. 1, the working principle will be further explained by combining with the detailed description of the corresponding structure of the electron beam control device 10 provided by the present disclosure.
For example, FIG. 3 is essentiallyIs a structural schematic diagram of one of the embodiments of the half-opening angle diaphragm plate, wherein, as shown in the diagram of FIG. 1, the diaphragm hole A on the horizontal axiso，A1，Aopt，A2，A3Are respectively illustrated in fig. 3 as corresponding to half opening angle αo，α1，αopt，α2，α3. Thereby, switching between different half aperture angles may be achieved by shifting the electron beam between the diaphragm apertures representing different half aperture angles.
Specifically, in one exemplary embodiment of the present disclosure, in the electron beam control device 10, one of the incident electron beam EB and the diaphragm member 9 is movable so that the electron beam is displaced to the selected diaphragm aperture, and the selected diaphragm aperture is selected based on the size of the electron beam determined according to the required field size.
Also, according to an exemplary embodiment of the present disclosure, as shown in fig. 3, in order to facilitate direct switching between two diaphragm holes among different diaphragm holes without having to transit through other diaphragm holes midway, thereby avoiding undesired electron beam size (e.g., beam diameter d) and beam current I size that may be momentarily introduced during switching, it may be implemented by arranging diaphragm holes on the diaphragm member with a certain regularity. For example, the plurality of diaphragm apertures are distributed on the diaphragm member in a surrounding arrangement as shown in fig. 3, or alternatively in a two-dimensional pattern arranged in an array, rather than a linear one-dimensional pattern (because switching between the plurality of diaphragm apertures arranged in a one-dimensional pattern necessarily results in the electron beam passing through the third diaphragm aperture during shifting), and in the two-dimensional pattern, the electron beam can be shifted directly between any two diaphragm apertures in a straight or smoothly curved path without passing through other diaphragm apertures. In other words, between any two different diaphragm apertures, it is provided that there is a path for the electron beam to shift through, enabling the electron beam to bypass the other diaphragm apertures located approximately between the two different diaphragm apertures, thereby enabling direct switching between desired half-aperture angles of the electron beam, and also between different combinations of beam diameter/beam current combinations, without undesired other half-aperture angles and other beam diameter/beam current combinations occurring during switching.
Specifically, as an exemplary embodiment of the arrangement of the diaphragm holes in the two-dimensional pattern in the wraparound arrangement or, alternatively, in the array arrangement, as shown in fig. 3, the plurality of diaphragm holes in the two-dimensional pattern includes: first diaphragm aperture AoptThe first diaphragm aperture AoptBased on the minimum size of the electron beam (e.g., beam diameter minimum d)min) And the size of the first diaphragm aperture is determined to be sufficient to pass the electron beam with the minimum size; and further diaphragm apertures distributed around the first diaphragm aperture, such that the arrangement of the first diaphragm aperture surrounded by the further diaphragm apertures is realized substantially around the first diaphragm aperture AoptThe overall pattern of the diaphragm holes is arranged around or in an array in a surrounding manner in an outward radiation manner. As a further embodiment of the present disclosure, for example, the first diaphragm aperture AoptIs arranged at the center of the diaphragm member.
Thereby, i.e. through such said first diaphragm aperture AoptA distribution layout surrounded by other diaphragm apertures in a single layer or in multiple layers such that for each diaphragm aperture (i.e. for each half aperture angle) it is angularly uniform around the first diaphragm aperture aoptThe arrangement is easy to realize the direct switching of the electron beams between any two diaphragm holes without passing through the transition of the third diaphragm hole, thereby being convenient to realize the direct switching between the required half aperture angles. Also, since each diaphragm aperture itself is also provided with a different size, for example, in a two-dimensional pattern arranged in a surrounding manner, the first diaphragm aperture a is angularly uniformly surroundedoptAll other diaphragm apertures arranged may be around said first diaphragm aperture aoptArranged in a single-layer or multi-layer ring shape.
Furthermore, as shown in FIG. 1, the beam diameter of the electron beam has a minimum value d due to the concave parabolic curve of the relationship between the half field angle and the beam diameterminAnd half opening angle αoptThe minimum value d corresponding to the beam diametermin. In order to obtain the minimum beam diameter d of the electron beamminIt is necessary to suppress the pair of electron beam control devices 10 as much as possibleInfluence of aberrations, thus, for example, as further shown in FIG. 3, diaphragm AoptArranged in the center of the optical axis of the incident electron beam, i.e. so that the first diaphragm aperture A is located at the center of the diaphragm memberoptCoinciding with the center of the optical axis of the incident electron beam. Thus, the diaphragm A provided at the central portion of the diaphragm member 9 in the form of a half-aperture diaphragm plateoptCorresponding to the smallest beam diameter d of the electron beamminAnd half opening angle αopt. It is to be noted that, in consideration of the aberration effect, AoptThe size is not necessarily the minimum of all diaphragm apertures.
According to an embodiment of the present disclosure, for example, as shown in fig. 2, the electron beam control apparatus 10 further includes a displacement member configured to displace one of the incident electron beam and the diaphragm member, and a control circuit 30 configured to be in electrical communication with the displacement member to control the displacement member such that the electron beam passes through a selected diaphragm aperture of the plurality of diaphragm apertures.
According to an embodiment of the present disclosure, as shown in fig. 2, the control circuit 30 further includes an input device 30a, where the input device 30a is configured to input a pixel size of the desired field of view, and further to determine the selected aperture according to the input pixel size, for example, by deriving a relationship between the input desired pixel size and a beam diameter ratio of the electron beam, a relationship between the pixel size and a half aperture angle, and thus a pixel size and a corresponding aperture, so as to select the aperture to be switched to.
In terms of the form of the diaphragm member and the relative displacement between the electron beam and the diaphragm member, according to one embodiment of the present disclosure, for example, the diaphragm member is configured as a movable multi-aperture diaphragm plate movably arranged on a plane perpendicular to an optical axis upon incidence of the electron beam, so that the electron beam projected thereon passes through a selected diaphragm aperture of the plurality of diaphragm apertures. In this case, instead of displacing the electron beam, the diaphragm itself can be displaced by means of an actuator, i.e. a relative displacement between the electron beam and the diaphragm, and thus a displacement of the electron beam between different diaphragm apertures in the diaphragm, can be achieved.
Correspondingly, in an embodiment of the disclosure, the displacement member comprises a displacement device adapted to move the movable multi-aperture diaphragm plate in a vacuum and/or ultra-clean environment, for example.
In particular, in some exemplary embodiments of the present disclosure, the displacement device comprises, for example, a driver arranged outside the vacuum and/or ultra-clean environment, and a motion feedthrough arranged in a kinematic coupling between the driver and the movable multi-aperture diaphragm plate in the vacuum and/or ultra-clean environment. The drive, for example, comprises at least one of a pneumatic drive, a manual drive, and a motor, or a combination thereof, and is configured to produce a driving action outside of the vacuum and/or ultra-clean environment. The motion feedthrough, for example, is at least partially within the vacuum and/or ultra-clean environment, and, for example, comprises: an input in moving communication with the driver to input the driving motion; a transmission/conversion mechanism for transmitting and/or converting the driving motion to generate an actuating motion, the actuating motion being synchronized with a speed at which the electron beam is switched among the plurality of diaphragm apertures; and an output in moving communication with the movable aperture plate for directly acting the actuating action on the movable aperture plate to displace it.
Additionally, in some alternative exemplary embodiments of the present disclosure, the displacement device comprises, for example, a non-lubricated and maintenance-free displacement device. In particular, the displacement device is, for example, a piezoelectric displacement device which is synchronizable with the speed at which the electron beam is switched among the plurality of diaphragm apertures, comprising a drive circuit arranged in or outside the vacuum and/or ultra-clean environment and a piezoelectric actuator arranged in the vacuum and/or ultra-clean environment. The drive circuit is configured to generate a drive electrical signal, and the piezoelectric actuator is disposed in electrical communication with the drive circuit to receive the drive electrical signal, and output an actuation action acting directly on the movable multi-aperture diaphragm plate in a vacuum and/or ultra-clean environment to displace the movable multi-aperture diaphragm plate, the actuation action being synchronized with a speed at which the electron beam switches among the plurality of diaphragm apertures. The piezoelectric displacement device is particularly a piezoelectric actuator which works under a vacuum or ultra-clean working condition at a high working frequency, does not need lubrication maintenance and the like of a conventional mechanical actuator, and can effectively avoid vacuum leakage which is possibly generated when a traditional mechanical diaphragm switching method is adopted.
Fig. 4 shows a schematic view of the position relationship of the deflectors 11-14 and the diaphragm member 9 in the form of an exemplary aperture plate in the electron beam control apparatus shown in fig. 2, the diaphragm apertures in different positions on the aperture plate being shown to correspond to different electron beam half-angles, respectively.
In terms of the form of the diaphragm member and the relative displacement between the electron beam and the diaphragm member, according to a further embodiment of the present disclosure, for example, the diaphragm member is alternatively configured as a fixed aperture plate on a plane perpendicular to the optical axis upon incidence of the electron beam. In this case, the electron beam, and not the diaphragm element, is displaced, so that a relative displacement between the electron beam and the diaphragm element, and thus a displacement of the electron beam between the different diaphragm apertures in the diaphragm element, is achieved. Correspondingly, in an embodiment of the present disclosure, as shown in fig. 4, the displacement member further includes a deflector assembly configured to deflect the electron beam, the deflector assembly including: at least one first deflector 11 upstream of said diaphragm member, configured to deviate the optical axis of the electron beam from the optical axis at incidence and to be directed towards said selected diaphragm aperture; and at least one second deflector 12 downstream of said diaphragm member, configured to deflect the electron beam exiting said selected diaphragm aperture such that the optical axis coincides again with the optical axis upon incidence. The control circuitry 30 is configured in electrical communication with a deflector assembly to control the deflector assembly to deflect the electron beam through selected ones of the plurality of diaphragm apertures.
In a still further embodiment of the present disclosure, as further illustrated in fig. 4, the deflector assembly further comprises: at least one third deflector 13 interposed between said first deflector 11 and said diaphragm member 9, configured to cause the electron beam deflected by said first deflector to pass through selected ones of said plurality of diaphragm apertures in a direction substantially parallel to, but not coincident with, the optical axis upon incidence; and at least one fourth deflector 14 interposed between said diaphragm 9 and said second deflector 12, configured to adjust the electron beam having passed through said diaphragm towards the optical axis upon incidence. More specifically, both the first deflector 11 and the third deflector 13 and both the second deflector 12 and the fourth deflector 14 are controlled separately or in linkage. In comparison, it is more efficient to perform the coordinated control of all the deflectors, i.e., the first to fourth deflectors, than the discrete control, or the partial coordinated control. The deflector assembly including both the first deflector 11 and the second deflector 12 serves as a simplified scheme, but a scheme in which the deflector assembly additionally includes the third deflector 13 and the fourth deflector 14 can more effectively make the electron beam after passing through the deflector assembly coincide with the optical axis than the simplified scheme, thereby more effectively suppressing aberration. According to the embodiment of the present disclosure as shown in fig. 2, at least one of the electron beam deflectors 11-14 located upstream and downstream of the aperture member 9 is used to deflect the electron beam so that the electron beam selectively passes through the aperture corresponding to a specific half aperture angle in the aperture member 9, thereby achieving fast switching of beam diameter and current of the electron beam. Moreover, the configuration can effectively avoid vacuum leakage which is possibly generated when the traditional mechanical diaphragm switching method is adopted.
As an alternative embodiment of the present disclosure, as a further modification of the embodiment in the case where the diaphragm member is configured as the aforementioned movable aperture plate, the displacement member thereof includes, in addition to the aforementioned actuator, for example, the aforementioned deflector assembly for a fixed aperture plate. The deflector assembly comprises a first deflector 11 and a second deflector 12, or a combination of a first deflector 11, a third deflector 13 and a second deflector 12, a fourth deflector 14, all of which are controlled separately or in linkage by a control circuit to cooperate with an actuator, for example an actuator for effecting a coarsely adjusted displacement of the movable aperture plate relative to the stationary electron beam, which in turn effects a displacement of the electron beam relative to the movable aperture plate that pauses the displacement, thereby together effecting a displacement of the electron beam between different apertures on the movable aperture plate, improving the efficiency with which the electron beam is switched between the different apertures, but increasing the complexity of the control by the control circuit.
With continued reference back to fig. 2, there is shown a schematic view of an electron beam inspection apparatus according to an embodiment of the present invention, which includes an electron beam imaging module equipped with the aforementioned electron beam control device 10.
According to another aspect of the present disclosure, as shown in fig. 2, the present disclosure also provides an electron beam imaging module configured to project an incident electron beam toward a surface of a sample to be measured to generate an electron beam image, the electron beam imaging module including: an electron beam emission source 1 configured to generate and emit an incident electron beam EB; the electron beam control device 10 according to the foregoing; a scanning deflector 17 disposed symmetrically with respect to the optical axis at the time of incidence of the electron beam at a downstream of the electron beam control device and configured to deflect the electron beam to scan on a sample surface 22 to be measured; and an outgoing electron detector 23 configured to detect an outgoing electron including at least one of a secondary electron and a backscattered electron generated by the incident electron beam projected to the sample 21 to be measured.
Specifically, as shown in fig. 2, the electron beam emission source 1 is, for example, in the form of an electron gun, such as a conventional schottky-type electron gun. An electron beam EB emitted by the electron gun passes through the electron beam control device 10 and then passes through the downstream scanning deflector 17 to scan a region of interest of the electron beam on a sample surface 22 to be measured of a sample 21 to be measured, and at least one of generated secondary electrons and backscattered electrons is detected by an outgoing electron detector 23.
In an embodiment of the present disclosure, the electron beam imaging module further comprises a lens assembly operable to project the electron beam into a beam spot onto a surface of a sample to be measured.
In a further embodiment of the present disclosure, as the beam current changes, the electron beam focal position changes accordingly due to coulomb interaction between electrons; and the deviation can be corrected by, for example, a dynamic focus lens. Thus, according to a specific embodiment of the present disclosure, as shown in fig. 2, the lens assembly may for example comprise an aberration correction device 18, the aberration correction device 18 being arranged downstream of the scanning deflector 17 and coaxially with the optical axis O upon incidence of the electron beam and being configured to perform a dynamic correction of the beam spot of the passing electron beam. In a further embodiment of the present disclosure, the aberration correction device 18 comprises or is in the form of a dynamic focus lens, such as an electrostatic dynamic focus lens, for example, which is configured to correct for changes in focal position (i.e. focal length) due to displacement towards a selected diaphragm aperture by adjustment of its excitation signal. In particular, the dynamic focus lens may be modified for the following situations: the change in focal position due to the up and down movement of the sample surface, the field curvature due to deflection, and the change in focal position due to coulomb interaction.
In a further embodiment of the present disclosure, as shown in fig. 2, the lens assembly further comprises, for example, an objective lens 19 configured to ultimately project the electron beam onto the surface of the sample to be measured, the objective lens 19 being arranged downstream of the aberration correction device 18 and coaxially with the optical axis O upon incidence of the electron beam. The electron beam is scanned on a sample surface 22 to be measured of a sample 21 to be measured (e.g., a silicon wafer) by a scanning deflector 17. The objective lens 19 images the cross spot of the electron beam finally onto the surface 22 of the sample to be measured, for example at an image point 20. The subsequent objective lens 19 focuses and projects the corrected cross spot of the electron beam to form an image on the sample surface 22 of the sample 21.
In the embodiment of the present disclosure, in order to improve the resolution of the generated image and suppress the charging effect of the sample surface 22 to be measured, for example, an additional electron beam deceleration voltage needs to be applied to the sample surface 22 to be measured, so that the total electron beam acceleration voltage value at the sample surface 22 to be measured is reduced to 1kV or even lower.
And, in addition to this, in the embodiment of the present disclosure, for example, in order to extract more secondary electrons from the surface 22 of the sample to be measured, an accelerating voltage (also referred to as a secondary electron accelerating voltage) needs to be applied to the objective lens 19 to act on the electron beam transmitted through the objective lens 19. The secondary electrons emitted from the sample surface 22 to be measured enter the lens barrel in the direction opposite to the primary electron beam incident on the sample surface under the combined action of the electron beam deceleration voltage of the sample surface 22 and the secondary electron acceleration voltage at the objective lens 19, and are projected to the emergent electron detector 23 to be captured to generate an electron beam image. Thereby, the secondary electrons and backscattered electrons emitted from the sample surface 22 to be measured are accelerated and enter the lens barrel, finally reach the outgoing electron detector 23 and are detected. As an example, as shown in fig. 2, the outgoing electron detector 23 is arranged between a downstream lens (e.g., shown at reference numeral 15 in the figure) and the scanning deflector 17 coaxially with the optical axis O at the time of incidence of the electron beam and apart from the objective lens 19.
In order to ensure the sealing of the optical path from the outside to avoid the interference of the external environment with the electron beam, the electron beam imaging module is usually disposed in the lens barrel as an integral electron optical system.
Also, in additional embodiments of the present disclosure, as shown in fig. 2, the lens assembly further comprises: a plurality of focusing lenses (e.g., first lens 3, second lens 7, third lens 15) arranged upstream of the aberration correction device 18 and coaxially with an optical axis O upon incidence of the electron beam, and configured to pre-focus the electron beam for projection onto the aberration correction device 18.
As a more specific example, as shown in fig. 2, the plurality of focusing lenses include: one or more upstream lenses (e.g., a first lens 3, a second lens 7, and one or more downstream lenses (e.g., a third lens 15, as shown) between the electron beam control device 10 and the scanning deflector 17 upstream of the electron beam control device 10. furthermore, the upstream lens (e.g., the second lens 7) most adjacent to the electron beam control device 10 is configured to converge the electron beam to form a beam spot 8 coinciding with the center of the first deflector 11, to ensure that the positions of the downstream crossover spot 16 and the electron beam at the sample surface image point 20 formed after passing through the electron beam control device 10 remain stable even under high-speed switching conditions between diaphragm apertures (otherwise, if the positions of the downstream crossover spot 16 and the image point 20 change after each diaphragm aperture switching, additional corrections must be made after each switching, the actual application requirements can not be met from the aspects of time consumption and operation complexity); and is reduced in comparison with a spot (e.g., the illustrated cross spot 4) adjacent to the electron beam emission source 1. The downstream cross spot 16 in the form of a beam spot formed by the downstream lens converging the electron beam is focused and projected onto the sample surface 22 to be measured in the form of a final beam spot 20 via the scanning deflector 17, the aberration correction device 18 and the objective lens 19. Also, the plurality of focusing lenses (such as the aforementioned first lens 3, second lens 7, third lens 15) include, for example, a specific form of one of: electrostatic lenses, magnetic lenses, hybrid lenses.
Also, in the electron beam imaging module as described above, the distance between the objective lens 19 and the sample surface 22 to be measured is defined as a working distance WD, and the working distance WD can be adjusted by adjusting the position of at least one of the objective lens 19 and the sample surface 22 to be measured, whereby the diaphragm aperture is selected based on the relationship between the size of the electron beam and the half aperture angle corresponding to different working distances WD (for example, the relationship curve between the beam diameter of the electron beam and the half aperture angle in the case of different distances WD1, WD2, and the like).
Also, in an exemplary embodiment of the present disclosure, as shown in fig. 2, for example, the electron beam imaging module further includes a second control circuit typically including a first driving and amplifying circuit 32 for driving the scanning deflector 17, a second driving and amplifying circuit 33 for driving the aberration correcting device 18, respectively, the first driving and amplifying circuit 32 and the second driving and amplifying circuit 33 being configured to be communicated to a deflection control circuit for controlling deflection of the electron beam. As an example, as shown in fig. 2, more specifically, the second control circuit further includes, for example: the aforementioned control circuit 30, which is further configured to drive the first deflector 11, the second deflector 12 or all four deflectors, i.e., the first to fourth deflectors 11-14, in the electron beam control apparatus 10; a processing circuit 31 for processing the image signal generated by the exit electron detector 23, a control circuit 32 for driving the scanning deflector 17, a control circuit 33 for driving the aberration correction device 18 to achieve dynamic focusing, a control circuit 34 for applying a speed-up voltage signal, and a control circuit 35 for applying a speed-down voltage signal. Note that the dynamic focus control circuit 34 and the deceleration voltage control circuit 35 may be used to realize the correction of the focal length.
Furthermore, in the exemplary embodiment of the present disclosure, as shown in fig. 2, in order to pre-adjust the shape of the electron beam, for example, the electron beam imaging module further includes at least one single aperture stop 2 fixedly disposed on the optical axis O at the time of incidence of the electron beam and located upstream of the electron beam control device 10, the single aperture stop 2 has a single aperture centrally arranged coaxially with the optical axis O at the time of incidence of the electron beam EB to constrain and roughly adjust the shape and beam current of the electron beam projected thereon, and further the cross spot 4 is formed by a subsequent condenser lens (e.g., the first lens 3).
Also, in an exemplary embodiment of the present disclosure, as illustrated in fig. 2, the electron beam imaging module further includes a beam shutter, the beam shutter including: a beam shutter electrode 5, the beam shutter electrode 5 being arranged so as to be deflected centering on a cross spot 4 formed by an upstream lens (e.g., first lens 3) apart from the electron beam control device 10; and a beam shutter member 6 located below said beam shutter electrode 5, wherein said beam shutter electrode 5 is configured to deflect the electron beam EB away from the optical axis O at incidence of the electron beam to effect switching off of the electron beam projected onto said beam shutter member 6. Specifically, for example, when the electron beam EB is controlled to scan the sample 21 to be measured, no voltage signal is applied to the beam shutter electrode 5, so that the electron beam passes through the aperture film hole 6a, for example, arranged centrally in the beam shutter member 6. When the scanning of the electron beam to the sample 21 to be measured needs to be closed, the control circuit of the beam gate electrode applies a deflection voltage signal to the beam gate electrode 5, and the electron beam EB bombards a part 6b outside the film hole on the beam gate diaphragm 6. A condenser lens 7 is provided below the beam shutter diaphragm 6 to reduce the cross spot 4 into a beam spot 8; an electron beam control device 10 is arranged below the condenser lens 7 and used for adjusting the half-field angle of the electron beam, namely the English electron beam diameter adjusting device in the invention.
As an alternative to beam gating, in another embodiment of the present disclosure, said first deflector 11 may be used as a beam gate while ensuring that the deflection center of the first deflector 11 coincides with the position of the beam spot 8, and thereby the beam gate electrode 5 and the beam gate diaphragm 6 are removed accordingly.
According to still another aspect of the present disclosure, there is provided an electron beam inspection apparatus M including: an electron beam imaging module according to the foregoing; and a displacement platform module comprising the following devices arranged in an overlapping manner: a horizontal displacement stage 25 (i.e., an X-Y displacement stage); a Z-displacement stage 24 configured to coarsely vary the working distance. A sample, such as a silicon wafer, is placed on a horizontal displacement stage 25 and is free to move in the XY plane perpendicular to the optical axis O.
Also, as an exemplary embodiment of the present disclosure, for example, the electron beam inspection apparatus M further includes a module for analyzing and processing an image generated by at least one of the secondary electron and backscattered electron signals acquired by the electron beam imaging module to realize defect detection or critical dimension measurement.
Additionally, according to the embodiment of the present disclosure, for example, the electron beam inspection apparatus M further includes a third control circuit, for example, a first sub-control circuit 36 that controls the Z-displacement stage 24 and the horizontal displacement stage 25, a second sub-control circuit 37 that processes signals generated by the laser interferometer 26 for position detection of the horizontal displacement stage 25, and a total control unit 38 that integrally controls the aforementioned circuits.
In addition, in recent years, with the rapid development of detection technology and measurement technology, a large amount of surface defect information of a mask and a silicon wafer can be more accurately acquired through corresponding equipment. And the position of the most probable defect in the chip can be effectively predicted by carrying out computer simulation analysis on the silicon chip graphic design information (such as GDS) and comparing the silicon chip graphic design information with past detection data. In addition, for a region where the defect existence probability is higher, the image resolution needs to be further improved. The pattern predicted by the analysis is inputted to the second sub-control circuit 37, and the pixel size value is set by 30 a. A diaphragm aperture switching method based on diaphragm apertures corresponding to different pixel sizes, and a detection method including the diaphragm aperture switching method will be described in detail below.
Fig. 5 is a schematic view illustrating the inspection and size measurement of a specific region using the electron beam inspection apparatus shown in fig. 2.
According to still another aspect of the present disclosure, referring to fig. 5, the present disclosure further provides an electron beam control method for adjusting the size of an incident electron beam by using the electron beam control apparatus, the electron beam control method comprising:
determining a desired half field angle of the electron beam based on the desired electron beam size;
selecting a diaphragm aperture from a plurality of spaced diaphragm apertures on a diaphragm member in the electron beam control device based on the determined half aperture angle;
shifting the electron beam to the selected aperture to adjust the size of the incident electron beam to a desired electron beam size.
An embodiment of the method is described in detail below with reference to fig. 5.
As a specific embodiment, as shown in fig. 5, for example, a schematic plan view of a chip CH to be detected in one exemplary test is specifically shown. As shown in fig. 5, as an example, where C1 is a certain area on chip CH, there is a lower priority in resolution in detection, so low resolution is mainly used for rough inspection; in contrast, the detection of region C2 requires a review with a moderate detection resolution, while region C3 requires a review with the highest level of resolution. Therefore, the following is assumed: for the detection of the region C1, a large-sized pixel and a large field of view (FOV) are required to perform the detection, for example, the field of view size is 5 μm, the total number of pixels is 1024 × 1024, the pixel size is 5 nm, and the corresponding beam diameter is 10 nm. Corresponding to this beam size, the corresponding half aperture angle α 3 and the corresponding diaphragm a3 need to be selected.
For the above application case, for example, the area-related information is input to the second sub-control circuit 37, and the pixel sizes for C1-C3 are input to the cell 30 a. In actual use, the pixel size value for each area detection process may be determined by the second sub-control circuit 37 and input to the input 30 a.
According to the embodiment of the present disclosure, in the above embodiment, after the inspection for the region C1 is completed, the inspection for the region C3 is started for the region C3, the pixel size is set to 1 nm, the beam diameter is set to 2 nm, and the field size is set to 1 μm, and for the beam diameter of 2 nm, the corresponding half-aperture angle α needs to be selectedoptAnd a diaphragm aperture AoptAfter the inspection for the region C3 is completed, inspection for the region C2 is further started for the region C2, inspection with moderate accuracy, i.e., setting the pixel size at 3 nm, the beam diameter at 6 nm, and the field size at 3 μm, is required, and for the beam diameter at 6 nm, the corresponding half-aperture angle α is required to be selectedoAnd a diaphragm aperture a 2. And shifting the electron beam to the selected diaphragm aperture based on the selected half aperture angle and the corresponding selected diaphragm aperture to achieve said half aperture angle switching. In order to realize the low-precision and high-precision detection, different detection equipment is required to be adopted in the past; the electron beam detection and size measurement equipment adopting the high-speed diaphragm switching device can realize the quick conversion of rough inspection and fine inspection through high-speed diaphragm switching.
Also, in an exemplary embodiment of the present disclosure, for example, the method includes: the beam current of the electron beam is changed by the change of the size and the half-aperture angle of the electron beam while adjusting the size of the incident electron beam.
In addition, as an example, simultaneous variation of the beam diameter and the beam current of the electron beam may also be additionally or alternatively performed with adjustment of the working distance.
For example, in critical dimension measurement (CD SEM) applications, the working distance needs to be as short as possible in order to suppress spherical aberration, and to obtain high resolution capability by reducing the beam diameter as much as possible, generally requiring the working distance to be set at 2-3 mm.
In contrast, for example, in inspection applications, the requirements for inspection speed are higher, so that a larger scanning area is generally emphasized rather than a smaller beam diameter. Thus, in the inspection, a working distance of 5 mm or more is more advantageous for the inspection.
Thus, a certain distance value between the working distance best suited for the dimensioning and the working distance best suited for (defect) detection needs to be chosen as a compromise as the actual working distance.
For example, for region C1 in the above embodiment, a larger working distance is typically used for rough inspection; whereas for the region C3 where review is required, smaller pixel size and beam diameter need to be switched. In the review mode (and the dimensional measurement mode), a smaller working distance is advantageous.
And the selection of the working distance can change the working distance to optimize imaging besides adjusting the beam diameter, the beam current and the like.
In particular embodiments, since the Z-displacement platform 24 is height adjustable, the working distance WD may be adjusted accordingly.
In an exemplary embodiment of the present disclosure, a single diaphragm member provided with a plurality of diaphragm holes may be employed.
Alternatively, since for a particular working distance WD1, a beam diameter-half opening angle curve as shown in fig. 1 may be obtained; if the working distance is changed to WD2, a beam diameter-half opening angle relationship curve different from the curve of fig. 1 is obtained. Therefore, for the review mode at the working distance WD2, a new set of aperture hole patterns is required. For example, as shown in fig. 3, which includes a set of diaphragm apertures suitable for use in the detection mode, another set of diaphragm apertures suitable for use in the review mode may be additionally provided (e.g., may be another diaphragm plate, or an additional diaphragm on the same diaphragm plate).
The technical scheme provided by the disclosure has at least one of the following advantages:
(1) at least some embodiments of the present disclosure adopt, for example, a method of using an electric field of an electron beam deflector to select a diaphragm aperture corresponding to a desired half aperture angle from a plurality of diaphragm apertures on a diaphragm member, thereby realizing rapid switching of a beam diameter and a current of an electron beam.
(2) Compared with the traditional mechanical transmission type diaphragm, the vacuum leakage can be avoided.
(3) In addition, if the technology of the invention is adopted, the electron beam diameter and the current of the electron beam detection and size measurement equipment can be switched in the detection process, and at least two functions of detection, size measurement and rechecking can be integrated in the same equipment.
In addition, it can be understood from the foregoing embodiments of the present disclosure that any technical solutions via any combination of two or more of them also fall within the scope of the present disclosure.
It should be understood that the directional terms in the specification of the present disclosure, such as "upper", "lower", "left", "right", etc., are used to explain the directional relationships shown in the drawings. These directional terms should not be construed to limit the scope of the present disclosure.
The embodiments of the present disclosure are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (19)
1. An electron beam control apparatus for adjusting a size of an incident electron beam, comprising a diaphragm member provided with a plurality of diaphragm holes arranged at intervals, wherein,
the plurality of diaphragm apertures are arranged such that each diaphragm aperture is positioned on the diaphragm member at a location corresponding to a half aperture angle of a desired electron beam, the half aperture angle being determined by a desired electron beam size, and each diaphragm aperture being sized sufficiently to pass the electron beam with a corresponding size, whereby the size of an incident electron beam can be adjusted by displacement of the electron beam to a selected diaphragm aperture of the plurality of diaphragm apertures; and
the plurality of diaphragm holes are distributed on the diaphragm piece in a surrounding type arrangement two-dimensional pattern, and in the two-dimensional pattern, an electron beam can be directly shifted between any two diaphragm holes in a linear or smooth curve path without passing through other diaphragm holes.
2. The electron beam control device according to claim 1, wherein one of the incident electron beam and the diaphragm member is movable so that the electron beam is displaced to the selected diaphragm aperture, and
the selected diaphragm aperture is selected based on the size of the electron beam determined according to the desired field size.
3. The electron beam control device of claim 1, wherein the plurality of diaphragm apertures in a two-dimensional pattern comprises:
a first diaphragm aperture, a position of which is determined based on a minimum size of the electron beam, and a size of which is determined to be sufficient to pass the electron beam having the minimum size; and
further diaphragm apertures distributed around the first diaphragm aperture.
4. The electron beam control device according to claim 3, wherein the first diaphragm hole is arranged at a center of the diaphragm member.
5. An electron beam control device according to claim 3, wherein the other diaphragm apertures are arranged in one or more rings distributed around the first diaphragm aperture in a two-dimensional pattern in a surrounding arrangement.
6. The electron beam control apparatus according to claim 2, further comprising:
a displacement member configured to displace one of the incident electron beam and the diaphragm member, and
a control circuit configured in electrical communication with the displacement member to control the displacement member such that the electron beam passes through a selected diaphragm aperture of the plurality of diaphragm apertures.
7. The electron beam control device of claim 6, the control circuit further comprising an input device configured for inputting a pixel size of a desired field of view, and further to determine the selected diaphragm aperture based on the inputted pixel size.
8. The electron beam control apparatus according to claim 6, wherein the diaphragm member is configured as a movable multi-aperture diaphragm plate movably arranged on a plane perpendicular to an optical axis upon incidence of the electron beam, so that the electron beam projected thereon passes through a selected one of the plurality of diaphragm apertures.
9. The electron beam control device according to claim 8, wherein the displacement member comprises a displacement device adapted to move the movable multi-aperture diaphragm plate in a vacuum and/or ultra-clean environment.
10. The electron beam control apparatus according to claim 9, wherein the displacement means includes:
a drive comprising at least one of a pneumatic drive, a manual drive, and a motor, the drive being disposed outside of the vacuum and/or ultra-clean environment and configured to produce a driving action; and
a motion feed-in arranged in a kinematic coupling between the driver and the movable multi-aperture diaphragm plate and configured to transmit and/or convert a driving action output by the driver into an actuating action acting directly on the movable multi-aperture diaphragm plate to displace the movable multi-aperture diaphragm plate, the actuating action being synchronized with a speed at which the electron beam switches among the plurality of diaphragm apertures.
11. The electron beam control apparatus of claim 9, wherein the displacement device is a piezoelectric displacement device comprising:
a drive circuit disposed in or outside the vacuum and/or ultra-clean environment and configured to generate a drive electrical signal; and
a piezoelectric actuator disposed in the vacuum and/or ultraclean environment and disposed in electrical communication with the drive circuit to receive the drive electrical signal and output an actuation action acting directly on the movable multi-aperture diaphragm plate to displace the movable multi-aperture diaphragm plate, the actuation action being synchronized with a speed at which the electron beam switches among the plurality of diaphragm apertures.
12. The electron beam control apparatus according to claim 1, wherein the diaphragm is configured as a fixed type aperture plate on a plane perpendicular to an optical axis at the time of incidence of the electron beam.
13. The electron beam control device according to any one of claims 8 to 11, wherein the displacement member further comprises a deflector assembly configured to deflect the electron beam, the deflector assembly comprising:
at least one first deflector upstream of the diaphragm member, configured to deviate the optical axis of the electron beam from the optical axis at incidence and to be directed towards the selected diaphragm aperture; and
at least one second deflector downstream of the diaphragm member, configured to deflect the electron beam exiting the selected diaphragm aperture such that the optical axis coincides with the optical axis upon incidence.
14. The electron beam control device of claim 13, wherein the deflector assembly further comprises:
at least one third deflector interposed between the first deflector and the aperture member, configured to cause the electron beam deflected by the first deflector to pass through selected ones of the plurality of aperture apertures in a direction substantially parallel to, but not coincident with, the optical axis at incidence; and
at least one fourth deflector interposed between the diaphragm member and the second deflector, configured to adjust the electron beam having passed through the diaphragm member toward an optical axis at the time of incidence,
wherein both the first deflector and the third deflector and both the second deflector and the fourth deflector are controlled separately or in linkage.
15. An electron beam imaging module configured to project an incident electron beam toward a surface of a sample under test to generate an electron beam image, the electron beam imaging module comprising:
an electron beam emission source configured to generate and emit an incident electron beam;
electron beam control device according to any of the preceding claims 11 to 14;
a scanning deflector disposed symmetrically with respect to an optical axis upon incidence of the electron beam at a downstream of the electron beam control device and configured to deflect the electron beam to scan a surface of a sample to be measured; and
an exit electron detector configured to detect an exit electron including at least one of a secondary electron and a backscattered electron generated by the incident electron beam being projected to the sample to be measured.
16. An electron beam inspection apparatus comprising:
the electron beam imaging module of claim 15; and
a displacement platform module comprising the following components arranged in an overlapping manner: a horizontal displacement platform; a Z-displacement stage configured to change the working distance.
17. The apparatus of claim 16, further comprising a module for analyzing an image generated from at least one of the secondary electron and backscattered electron signals collected by the electron beam imaging module to achieve defect detection or critical dimension measurement.
18. An electron beam control method for adjusting a size of an incident electron beam using the electron beam control apparatus according to any one of claims 1 to 14, the electron beam control method comprising:
determining a desired half field angle of the electron beam based on the desired electron beam size;
selecting a diaphragm aperture from a plurality of spaced diaphragm apertures on a diaphragm member in the electron beam control device based on the determined half aperture angle;
shifting the electron beam to the selected aperture to adjust the size of the incident electron beam to a desired electron beam size.
19. The electron beam control method according to claim 18, wherein the beam current of the electron beam is changed by a change in the size and the half angle of the electron beam while adjusting the size of the incident electron beam.
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| CN111446141A (en) * | 2020-03-05 | 2020-07-24 | 中国电子科技集团公司第三十八研究所 | Multi-path high-precision high-voltage power supply |
| CN116190185A (en) * | 2021-05-27 | 2023-05-30 | 中科晶源微电子技术（北京）有限公司 | Deflector mechanism for reducing phase difference and scanning electron microscope |
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| CN103456589A (en) * | 2012-05-31 | 2013-12-18 | 睿励科学仪器（上海）有限公司 | Diaphragm for adjusting particle beam with multipole lenses and device including same |
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Address after: 100176 building 12, yard 156, Jinghai 4th Road, Beijing Economic and Technological Development Zone, Daxing District, Beijing Patentee after: Dongfang Jingyuan Microelectronics Technology (Beijing) Co.,Ltd. Address before: 100176 building 12, yard 156, Jinghai 4th Road, Beijing Economic and Technological Development Zone, Daxing District, Beijing Patentee before: DONGFANG JINGYUAN ELECTRON Ltd. |