CN116190184A - Scanning electron microscope objective lens system and scanning focusing method - Google Patents
Scanning electron microscope objective lens system and scanning focusing method Download PDFInfo
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- CN116190184A CN116190184A CN202310084443.2A CN202310084443A CN116190184A CN 116190184 A CN116190184 A CN 116190184A CN 202310084443 A CN202310084443 A CN 202310084443A CN 116190184 A CN116190184 A CN 116190184A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- 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
- G01N23/22—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 measuring secondary emission from the material
- G01N23/225—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 measuring secondary emission from the material using electron or ion
- G01N23/2251—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 measuring secondary emission from the material using electron or ion using incident electron beams, e.g. scanning electron microscopy [SEM]
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- H—ELECTRICITY
- 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
- H01J37/10—Lenses
- H01J37/14—Lenses magnetic
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- H—ELECTRICITY
- 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
- H01J37/10—Lenses
- H01J37/14—Lenses magnetic
- H01J37/141—Electromagnetic lenses
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- H—ELECTRICITY
- 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
- H01J37/147—Arrangements for directing or deflecting the discharge along a desired path
- H01J37/1472—Deflecting along given lines
- H01J37/1474—Scanning means
- H01J37/1475—Scanning means magnetic
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- H—ELECTRICITY
- 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
- H01J37/21—Means for adjusting the focus
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- H—ELECTRICITY
- 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
- H01J37/244—Detectors; Associated components or circuits therefor
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- H—ELECTRICITY
- 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
- H01J37/26—Electron or ion microscopes; Electron or ion diffraction tubes
- H01J37/28—Electron or ion microscopes; Electron or ion diffraction tubes with scanning beams
Abstract
The embodiment of the disclosure provides a scanning electron microscope objective lens system and a scanning focusing method, wherein the objective lens system comprises a magnetic lens, a first deflection device, a detection device, a second deflection device and a sample stage; wherein: the magnetic lens comprises a main body part and a magnetic conductive pole shoe; a first deflection device, located between the inner wall of the main body portion and the optical axis of the electron beam, for changing the movement direction of the incident electron beam; the detection device is positioned between the first deflection device and the second deflection device and is used for receiving signal electrons generated by the to-be-detected sample acted on the sample table by the electron beam; the second deflection device is positioned between the main body part and the magnetic conductive pole shoe and is used for changing the movement direction of the electron beam; the detection device, the second deflection device, the magnetic conduction pole shoe and the sample table form an electric lens; the electric lens and the magnetic lens form a composite objective lens for converging the electron beam.
Description
Technical Field
The present disclosure relates to the field of scanning electron microscope technology, and relates to, but is not limited to, a scanning electron microscope objective system and a scanning focusing method.
Background
Scanning electron microscopes, which have a higher resolution than optical microscopes, are widely used in various fields requiring fine observation of the structure of a substance, including semiconductors, biomedicine, materials, and the like. Since most of scanning electron microscopes focus electron beams by using a magnetic lens, and the magnetic field of the magnetic lens is not zero at the sample to be measured, i.e., an immersion objective lens, when observing magnetic or ferromagnetic materials, the magnetic field covering the sample to be measured is disturbed by the magnetic sample to be measured, and a clear image cannot be obtained, thereby causing various inconveniences.
Disclosure of Invention
Embodiments of the present disclosure provide a scanning electron microscope objective system and a scanning focusing method.
In a first aspect, embodiments of the present disclosure provide a scanning electron microscope objective system comprising: the device comprises a magnetic lens, a first deflection device, a detection device, a second deflection device and a sample stage; wherein: the magnetic lens comprises a main body part and a magnetic conductive pole shoe; the first deflection device is positioned between the inner wall of the main body part and the optical axis of the electron beam and is used for changing the movement direction of the incident electron beam; the detection device is positioned between the first deflection device and the second deflection device and is used for receiving signal electrons generated by a sample to be detected, which is acted on the sample stage by the electron beam; the second deflection device is positioned between the main body part and the magnetic conductive pole shoe and is used for changing the movement direction of the electron beam; the detection device, the second deflection device, the magnetic conduction pole shoe and the sample table form an electric lens; the electric lens and the magnetic lens form a composite objective lens for converging the electron beam.
In some embodiments, the opening of the magnetic conductive pole shoe faces the sample to be measured, and the extending direction of the tail end of the magnetic conductive pole shoe is horizontal and the same as the extending direction of the tail end of the magnetic conductive shell of the main body part.
In some embodiments, the magnetic field strength maximum of the magnetic lens is located between the opening of the magnetically permeable housing of the body portion and the opening of the magnetically permeable pole piece; the magnetic field of the magnetic lens has a magnetic field strength of 0 at the position of the sample to be measured.
In some embodiments, the voltage V of the magnetically permeable pole piece 1 Voltage V with the sample stage 2 The relation is: v (V) 2 -5 kilovolts (kV) is less than or equal to V 1 ≤V 2 +5kV, voltage V of the sample stage 2 Ranging from-15 kV to 0kV; the voltage of the magnetic conduction shell is 0kV.
In some embodiments, the magnetically permeable pole piece central bore diameter, the second deflector central bore diameter, and the detector central bore diameter decrease in sequence.
In some embodiments, the objective lens system further comprises: a first isolation structure for isolating the main body portion from the magnetically permeable pole piece; and/or a second isolation structure for isolating the second deflection means, the detection means and the body portion.
In a second aspect, an embodiment of the present disclosure provides a scanning focusing method, including: when the incident electron beam passes through the central axis of the scanning electron microscope objective system, converging the electron beam through the composite objective system, and changing the movement direction of the electron beam through the voltage applied to the first deflection device and the second deflection device to obtain the electron beam of the sample to be detected acting on the sample stage; wherein the composite objective lens comprises a magnetic lens and an electric lens; the electric lens sequentially comprises a detection device, the second deflection device, a magnetic conduction pole shoe of the magnetic lens and the sample stage from top to bottom.
In some embodiments, the voltage applied to the first deflection device and the second deflection device is one of: the voltages applied to the first deflection device and the second deflection device are alternating voltages; the voltage applied to the first deflection device is alternating voltage, and the voltage applied to the second deflection device is constant voltage; wherein the voltage range value of the constant voltage is-5 kV to 5kV; the voltage applied to the first deflection device is alternating voltage, and the voltage applied to the second deflection device is superposition voltage of a constant voltage and a constant deflection voltage.
In some embodiments, the method further comprises: and after the electric lens reversely accelerates the signal electrons generated by the electron beam acting on the sample to be detected and changes the movement direction of the signal electrons, the signal electrons are received by the detection device.
In the embodiment of the disclosure, firstly, the magnetic field distribution of the magnetic lens is changed by arranging the magnetic conductive pole shoe in the magnetic lens, so that the magnetic field intensity of the position of the sample to be detected is 0, namely the objective lens system is non-immersed, and the scanning electron microscope objective lens system can observe not only the non-magnetic sample to be detected but also the magnetic sample to be detected, and can obtain high-quality images; secondly, a first deflection device is arranged between the inner wall of the main body part of the magnetic lens and the optical axis of the electron beam, a second deflection device is arranged between the main body part and the magnetic conducting pole shoe, the detection device, the second deflection device, the magnetic conducting pole shoe and the sample table form an electric lens, the electric lens and the magnetic lens form a composite objective lens, the composite objective lens focuses and converges the incident electron beam, the electric lens decelerates the converged electron beam, the decelerated electron beam scans on the sample to be detected under the action of a deflection field generated by the second deflection device and the second deflection device so as to generate signal electrons, and the detection device collects the signal electrons.
Drawings
In the drawings (which are not necessarily drawn to scale), like numerals may describe similar components in different views. Like reference numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example and not by way of limitation, various embodiments discussed herein.
FIG. 1 is a schematic diagram of a scanning electron microscope objective system according to an embodiment of the present disclosure;
FIG. 2 is a schematic diagram of electric field and magnetic field distribution in a scanning electron microscope objective system according to an embodiment of the present disclosure;
FIG. 3 is a schematic diagram of a second deflector according to an embodiment of the present disclosure;
FIG. 4 is a schematic illustration of another second deflector shape provided by an embodiment of the present disclosure;
FIG. 5 is a schematic diagram of voltage conditions of each portion of an electro-lens according to an embodiment of the disclosure;
FIG. 6 is a schematic diagram of the relationship between the sizes of the center hole of the magnetic pole piece, the center hole of the second deflecting device and the center hole of the detecting device according to the embodiment of the present disclosure;
fig. 7 is a schematic flowchart of an implementation of a scanning focusing method according to an embodiment of the disclosure;
fig. 8 is a schematic diagram of a first scanning focusing method according to an embodiment of the disclosure;
FIG. 9 is a schematic diagram of a second scanning focusing method according to an embodiment of the present invention;
fig. 10 is a schematic diagram of a third scanning focusing method according to an embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that the present disclosure may be practiced without one or more of these details. In other instances, well-known features have not been described in order to avoid obscuring the present disclosure; that is, not all features of an actual implementation are described in detail herein, and well-known functions and constructions are not described in detail.
In the drawings, the size of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like numbers refer to like elements throughout.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.
In view of this, the embodiments of the present disclosure provide a non-immersion objective system, such that the magnetic field of the magnetic lens is zero at the sample to be measured, that is, the sample to be measured is not in the focused magnetic field region formed by the magnetic lens. Therefore, when observing a magnetic or ferromagnetic sample, the electron beam is not affected by the magnetic permeability of the sample to be measured, so that a high-quality image can be obtained on the magnetic sample to be measured.
Embodiments of the present disclosure provide a scanning electron microscope objective system, referring to fig. 1, comprising a magnetic lens, a first deflection device 103, a second deflection device 104, a detection device 105, and a sample stage 106; wherein:
the magnetic lens comprises a main body part 101 and a magnetic conductive pole piece 102;
the first deflection device 103 is positioned between the inner wall of the main body part 101 and the optical axis of the electron beam, and is used for changing the movement direction of the incident electron beam;
the second deflection device 104 is located between the main body 101 and the magnetic conductive pole piece 102, and is used for changing the movement direction of the electron beam;
the detecting device 105 is located between the first deflecting device 103 and the second deflecting device 104, and is used for receiving signal electrons generated by the sample to be detected, which is acted on the sample stage by the electron beam;
the detection device 105, the second deflection device 104, the magnetically conductive pole piece 102 and the sample stage 106 form an electro-lens; the electric lens and the magnetic lens form a composite objective lens for converging the electron beam.
In the use process, the incident electron beam is converged through the compound objective lens when passing through the central axis 109 of the objective lens system, and the movement direction of the electron beam is changed through the voltage applied to the first deflection device 103 and the second deflection device 104, so as to obtain the electron beam of the sample to be tested acting on the sample stage; the detection device collects signal generation electrons acted on the sample to be detected by the electron beam.
In the embodiment of the disclosure, firstly, the magnetic field distribution of the magnetic lens is changed by arranging the magnetic conductive pole shoe in the magnetic lens, so that the magnetic field intensity of the position of the sample to be detected is 0, namely the objective lens system is non-immersed, and the scanning electron microscope objective lens system can observe not only the non-magnetic sample to be detected but also the magnetic sample to be detected, and can obtain high-quality images; secondly, a first deflection device is arranged between the inner wall of the main body part of the magnetic lens and the optical axis of the electron beam, a second deflection device is arranged between the main body part and the magnetic conducting pole shoe, the detection device, the second deflection device, the magnetic conducting pole shoe and the sample table form an electric lens, the electric lens and the magnetic lens form a composite objective lens, the composite objective lens focuses and converges the incident electron beam, the electric lens decelerates the converged electron beam, the decelerated electron beam scans on the sample to be detected under the action of a deflection field generated by the second deflection device and the second deflection device so as to generate signal electrons, and the detection device collects the signal electrons.
It should be noted that, the compound objective lens is used for converging the electron beam; wherein the electron beam is generated by an electron source and is incident into an objective lens system. The electron sources are divided into field emission sources and heat emission sources, wherein the field emission sources are divided into a heat field and a cold field, and the heat emission sources are divided into tungsten wires, lanthanum hexaboride and the like. In the embodiments of the present disclosure, the electron source may be any electron source for generating an electron beam.
In some embodiments, referring to fig. 1, the body portion 101 of the magnetic lens may include an excitation coil 101a and a magnetically permeable housing 101b. The magnetically permeable housing 101b is made of magnetically permeable material, wherein the magnetically permeable material may comprise a soft magnetic material, such as iron, a ferroalloy, or other relatively high permeability material in a ferromagnetic material for providing a low reluctance path for the magnetic field generated by the excitation coil.
The excitation coil 101a may be formed by winding a litz wire; in practice, the focusing characteristics of the magnetic lens can be changed by changing the current in the excitation coil 101 a.
The openings of the magnetic conductive shell 101b facing the sample to be measured are an inner pole piece 101c and an outer pole piece 101d respectively. The pole piece close to the optical axis or the central axis 109 of the objective system is the inner pole piece 101c, and the pole piece far from the optical axis is the outer pole piece 101d, wherein the optical axis refers to the optical central axis of the electron beam.
In some embodiments, with continued reference to fig. 1, the magnetically permeable pole piece 102 is open towards the sample (or sample stage 106) to be measured, and the extension of the end of the magnetically permeable pole piece 102 is in a horizontal direction, which is the same as the extension of the end of the magnetically permeable housing 101b (or outer pole piece 101 d) of the body portion 101. The direction of the magnetic field generated by the magnetic conduction shell is the same as the placement direction of the magnetic conduction pole shoe, so that the magnetic circuit is kept smooth, the leakage magnetic field is reduced, and the non-immersed effect is improved.
The magnetic conducting pole shoe has the function of magnetic conducting and changing the magnetic field distribution, so that the magnetic field intensity of the sample to be measured is 0, namely, the magnetic lens is a non-immersed magnetic lens. Referring to fig. 2, curve B (z) 120 is a schematic diagram of the distribution of the magnetic field of the magnetic lens on the optical axis, and it can be seen that the maximum value of the magnetic field strength of the magnetic lens is located between the opening of the magnetic conductive housing and the opening of the magnetic conductive pole piece; the magnetic field of the magnetic lens has a magnetic field strength of 0 at the position of the sample to be measured.
The magnetic pole shoe is not only a part of the magnetic lens, but also a part of the electric lens, namely the magnetic pole shoe belongs to both the magnetic lens and the electric lens.
In some embodiments, the voltage V of the magnetically permeable pole piece 1 Voltage V with the sample stage 2 The relation is: v (V) 2 -5kV≤V 1 ≤V 2 +5kV, voltage V of the sample stage 2 Ranging from-15 kV to 0kV; the voltage of the magnetic conduction shell is 0kV. Here, the voltage of the magnetic conductive pole shoe can be V 2 May be an adjustable voltage; the magnetically permeable housing may be grounded. In this way, the electro-lens generates a deceleration field between the magnetic lens and the sample stage (or sample to be measured), reducing the velocity of the electron beam, and allowing the electron beam to reach the sample with a lower landing energy, so as to reduce the charge effect of the non-conductive sample.
In practice, the second voltage V 2 Can be in the range of-15 kV to V 2 Less than or equal to 0kV; first voltage V 1 Can be in the range of V 2 -5kV≤V 1 ≤V 2 +5Kv, i.e. -20 kV.ltoreq.V 1 ≤5kV。
With continued reference to fig. 1, the first deflection means 103 is located inside the body portion 101 of the magnetic lens. In practice, the first deflection means 103 may comprise at least one sub-deflector, for example the first deflection means 103 comprises two sub-deflectors, a first sub-deflector 103a and a second sub-deflector 103b, respectively. Wherein the first sub-deflector 103a is located above the second sub-deflector 103b, the first sub-deflector 103a and the second sub-deflector 103b may all be electric deflectors, or all be magnetic deflectors, or a combination of electric and magnetic deflectors.
In some embodiments, the first deflecting means may comprise a plurality of sub-deflectors arranged in a top-down order in the direction of the central axis of the objective system. Also, when the plurality of sub-deflectors are a combination of an electric deflector and a magnetic deflector, the positions of the electric deflector and the magnetic deflector are not limited. For example, when the first deflecting means includes 4 sub-deflectors, an electric deflector, a magnetic deflector, and a magnetic deflector are provided in this order from top to bottom in the direction of the central axis of the objective lens system; or an electric deflector, a magnetic deflector, an electric deflector and a magnetic deflector are sequentially arranged from top to bottom in the central axis direction of the objective lens system; or a magnetic deflector, an electric deflector and an electric deflector are arranged in sequence from top to bottom in the central axis direction of the objective lens system. Of course, there are various combinations of types and positions of the plurality of sub-deflectors, which are not illustrated in detail herein.
In some embodiments, the first deflection device or the second deflection device is an eight-lobe structure; alternatively, the first deflection device or the second deflection device is of a twelve-flap structure. In practice, the first deflection means and the second deflection means may each be of eight-lobe configuration; alternatively, the first deflection means and the second deflection means may each be of twelve-lobed configuration; or the first deflection device is of an eight-valve structure, and the second deflection device is of a twelve-valve structure; alternatively, the second deflection device is in an eight-lobe structure, the first deflection device is in a twelve-lobe structure, and the structures of the first deflection device and the second deflection device are not limited in the embodiments of the present disclosure.
With continued reference to fig. 1, a second deflector 104 is located below the opening of the magnetic lens body 101, and the second deflector 104 may be an electrical deflector. In practice, the electrical deflector is an eight-lobe electrical deflector 104a as shown in fig. 3, or a twelve-lobe electrical deflector 104b as shown in fig. 4. The more the number of lobes of the electric deflector is, the more the structural shape of the electric deflector is close to a circle, the more symmetrical and the more accurate the deflection is, thereby the deflection effect is better.
The incident electron beam acts on the sample to be measured to generate signal electrons. Wherein the signal electrons are electrons generated by the electron beam acting on the sample, comprising: secondary electrons and backscattered electrons. Backscattered electrons refer to energetic electrons that escape again from the sample surface after the incident electrons interact with the sample (elastic and inelastic scattering). Secondary electrons are electrons generated by ionizing electrons (valence band or conduction band electrons) at the outer layer of sample atoms after the incident electrons interact with the sample.
In practice, the detection device is grounded, i.e. the voltage of the detection device is 0. The detection means may be a circular semiconductor detector with a central hole, an avalanche detector or a detector consisting of a scintillator and a light pipe. The detection means 105 are located between the inner pole piece 101c and said second deflection means 104, i.e. the second deflection means 104 are located below the detection means 105 and above said magnetically permeable pole piece 102.
The sample stage carries a sample to be measured, and the sample to be measured can be a magnetic sample or a non-magnetic sample.
In the embodiment of the disclosure, the electric lens comprises a detection device, a second deflection device, a magnetic conduction pole shoe and a sample table, and is used for converging electron beams, accelerating signal electrons reversely and changing signal electron tracks simultaneously, and improving collection efficiency. In some embodiments, the potential of each part of the electro-lens is schematically shown in FIG. 5, wherein the detecting device 105 is grounded and the second deflecting device 104 is connected to a constant voltage V p The magnetic conductive pole shoe 102 is connected with a voltage V 1 Sample stage 106 is connected to a voltage V 2 . Referring to FIG. 2, curve E 1 (z) 121 is the magnetic conductive pole shoe at an adjustable voltage V 1 Schematic diagram of the electric field formed under, curve E 1 (z) 122 is the second deflection device at voltage V p Schematic of the electric field formed below. Thus, each part of the electric lens has a potential, and the electric lens is matched with the electric lens to perform deceleration, focusing and deflection on the incident electron beam, and perform acceleration collection on the signal electron beam.
In some embodiments, with continued reference to fig. 5, signal electrons 110 generated by the electron beam on the sample by the electro-lens are accelerated toward the detection device 105 while the trajectory is beam-shaped, and may pass through the central holes of the magnetically permeable pole piece 102 and the second deflection device 104, and be efficiently collected by the detection device 105.
The magnetic conductive pole shoe, the second deflection device and the detection device are all provided with central holes. In some implementations, referring to FIG. 6, the magnetically permeable pole piece 102 has a central bore diameter D 1 The diameter D of the central hole of the second deflection device 104 2 And the diameter D of the central hole of the detecting device 105 3 Sequentially decreasing, i.e. D 3 ＜D 2 ＜D 1 . The electric lens effect and the diameter of the central hole are related, so that the electric lens effect can be better on the one hand; on the other hand, the signal electrons are convenient to pass through, so that the signal electrons are efficiently collected by the detection device.
Since the main body 101 is grounded and the magnetic pole piece 102 is connected to an adjustable voltage, the voltage between them is different, so an isolation structure is required between them. In some embodiments, referring to fig. 1, the objective lens system further comprises:
a first isolation structure 108 for isolating the body portion 101 from the magnetically permeable pole piece 102; in practice, the material of the first isolation structure 108 may be a non-conductive material, such as ceramic; the magnetically permeable housing 101b and the magnetically permeable pole piece 102 are isolated by a first isolation structure 108.
And/or a second isolation structure 107 for isolating said second deflection means 104, said detection means 105 and said body portion 101. In practice, the material of the second isolation structure 107 may also be ceramic; the second deflector 104, the detecting means 105 and the body portion 101 are isolated by a second isolation structure 107.
The embodiment of the present disclosure also provides a scanning focusing method, referring to fig. 7, including the following step S701:
step S701, when the incident electron beam passes through the central axis of the scanning electron microscope objective system, converging the electron beam through the compound objective system, and changing the movement direction of the electron beam through the voltage applied to the first deflection device and the second deflection device to obtain the electron beam of the sample to be detected acting on the sample stage;
wherein the composite objective lens comprises a magnetic lens and an electric lens; the electric lens sequentially comprises a detection device, the second deflection device, a magnetic conduction pole shoe of the magnetic lens and the sample stage from top to bottom.
The incident electron beam passing through the central axis means: the electron beam passes from incidence on the body portion of the objective lens system until the electron beam reaches the sample to be measured. In implementation, when an incident electron beam passes through the central axis, the composite objective lens system converges the electron beam, and simultaneously applies voltage to the first deflection device and the second deflection device to change the movement direction of the electron beam; the first deflection device and the second deflection device may be applied with voltages at all times, and the timing of applying the voltages is not limited in the embodiments of the present disclosure.
In the embodiment of the disclosure, the electron beam is converged by the composite objective lens (comprising a magnetic lens and an electric lens) when passing through the central axis of the objective lens system, the electric lens is decelerated, and the first deflection device and the second deflection device change the movement direction and then act on the sample to generate signal electrons. The magnetic field distribution of the magnetic lens is changed by arranging the magnetic conductive pole shoe in the magnetic lens, so that the magnetic field intensity of the position of the sample to be detected is 0, namely the objective lens system is non-immersed, and the scanning electron microscope objective lens system can observe not only the non-magnetic sample to be detected but also the magnetic sample to be detected, and can obtain high-quality images.
In some embodiments, the voltage applied to the first deflection device and the second deflection device is one of:
the voltages applied to the first deflection device and the second deflection device are alternating voltages;
the voltage applied to the first deflection device is alternating voltage, and the voltage applied to the second deflection device is constant voltage; wherein the voltage range value of the constant voltage is-5 kV to 5kV;
the voltage applied to the first deflection device is alternating voltage, and the voltage applied to the second deflection device is the superposition voltage of a constant voltage and a constant deflection voltage.
The alternating voltage may be a constant voltage V p The voltage obtained after the fluctuation is performed on the basis.
Referring to fig. 8, alternating voltages are simultaneously applied to the first deflection means 103 and the second deflection means 104, at which time both sets of deflection means deflect the electron beam simultaneously. The movement locus of the electron beam is as shown by a broken line in fig. 8, and the electron beam is deflected in a direction away from the optical axis while passing through the first sub-deflector 103a in the first deflecting device 103; when the electron beam passes through the second sub-deflector 103b in the first deflector 103, the electron beam is deflected in a direction approaching the optical axis; as the electron beam passes the second deflection means 104, the electron beam is deflected away from the optical axis, so that a large deflection field (i.e. a large field view) is obtained, thereby enabling the focused electron beam to be scanned over the sample.
In the case of a constant voltage applied, the second deflection means cannot deflect, that is to say cannot change the direction of movement of, the electron beam. Referring to fig. 9, the second deflection device 104 may apply only a constant voltage V p Instead of applying an alternating voltage, the first deflection means 103 apply an alternating voltage, in which case only the first deflection means 103 deflect the electron beam. The motion track of the electron beam is shown by a dotted line in fig. 9, where the first sub-deflector 103a and the second sub-deflector 103b in the first deflection device 103 deflect the electron beam respectively once, and the deflection field is smaller, so that the converged electron beam scans on the sample, and at this time, the deflection field is matched with the objective lens, which is beneficial to reducing distortion of the electron beam and improving resolution of the scanning electron microscope.
Referring to fig. 10, an alternating voltage is applied to the first deflection device, and a superimposed voltage of a constant voltage and a constant deflection voltage is applied to the second deflection device 104. The second deflection means then act to cause a constant tilt of the electron beam, which the first deflection means scans to image, which can be used in situations where a tilt view of the sample is required.
In some embodiments, the method further comprises: and after the electric lens reversely accelerates the signal electrons generated by the electron beam acting on the sample to be detected and changes the movement direction of the signal electrons, the signal electrons are received by the detection device. This can improve the collection efficiency of the signal electrons.
After the detection device receives the signal electrons, the signal electrons in different detection areas can be subjected to operation processing and then output to the image processing device for processing to form an image, so that an image comprising the appearance of the sample to be detected is obtained.
In several embodiments provided by the present disclosure, it should be understood that the disclosed apparatus and methods may be implemented in a non-targeted manner. The above described device embodiments are only illustrative, e.g. the division of the units is only one logical function division, and there may be other divisions in practice, such as: multiple units or components may be combined or may be integrated into another system, or some features may be omitted, or not performed. In addition, the components shown or discussed are coupled to each other or directly.
The units described as separate units may or may not be physically separate, and units displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units; some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
The features disclosed in the several method or apparatus embodiments provided in the present disclosure may be arbitrarily combined without any conflict to obtain new method embodiments or apparatus embodiments.
While the foregoing is directed to embodiments of the present disclosure, the scope of the embodiments of the present disclosure is not limited to the foregoing, and any changes and substitutions that are within the scope of the embodiments of the present disclosure will be readily apparent to those skilled in the art. Therefore, the protection scope of the embodiments of the present disclosure shall be subject to the protection scope of the claims.
Claims (9)
1. A scanning electron microscope objective lens system, which is characterized by comprising a magnetic lens, a first deflection device, a detection device, a second deflection device and a sample stage; wherein:
the magnetic lens comprises a main body part and a magnetic conductive pole shoe;
the first deflection device is positioned between the inner wall of the main body part and the optical axis of the electron beam and is used for changing the movement direction of the incident electron beam;
the detection device is positioned between the first deflection device and the second deflection device and is used for receiving signal electrons generated by a sample to be detected, which is acted on the sample stage by the electron beam;
the second deflection device is positioned between the main body part and the magnetic conductive pole shoe and is used for changing the movement direction of the electron beam;
the detection device, the second deflection device, the magnetic conduction pole shoe and the sample table form an electric lens; the electric lens and the magnetic lens form a composite objective lens for converging the electron beam.
2. The objective lens system according to claim 1, wherein the opening of the magnetically permeable pole piece faces the sample to be measured, and the extension direction of the end of the magnetically permeable pole piece is in a horizontal direction, which is the same as the extension direction of the end of the magnetically permeable housing of the main body portion.
3. The objective lens system of claim 1, wherein a magnetic field strength maximum of the magnetic lens is located between an opening of the magnetically permeable housing of the body portion and an opening of the magnetically permeable pole piece; the magnetic field of the magnetic lens has a magnetic field strength of 0 at the position of the sample to be measured.
4. An objective lens system as recited in claim 2 or 3, wherein the voltage V of the magnetically permeable pole piece 1 Voltage V with the sample stage 2 The relation is: v (V) 2 -5kV≤V 1 ≤V 2 +5kV, voltage V of the sample stage 2 Ranging from-15 kV to 0kV; the voltage of the magnetic conduction shell is 0kV.
5. An objective lens system as recited in any one of claims 1-3, wherein the magnetically permeable pole piece central bore diameter, the second deflector central bore diameter and the detector central bore diameter decrease in sequence.
6. The objective lens system of claim 5, further comprising:
a first isolation structure for isolating the main body portion from the magnetically permeable pole piece;
and/or a second isolation structure for isolating the second deflection means, the detection means and the body portion.
7. A scanning focusing method, comprising:
when the incident electron beam passes through the central axis of the scanning electron microscope objective system, converging the electron beam through the composite objective system, and changing the movement direction of the electron beam through the voltage applied to the first deflection device and the second deflection device to obtain the electron beam of the sample to be detected acting on the sample stage;
wherein the composite objective lens comprises a magnetic lens and an electric lens; the electric lens sequentially comprises a detection device, the second deflection device, a magnetic conduction pole shoe of the magnetic lens and the sample stage from top to bottom.
8. The method of claim 7, wherein the voltage applied to the first deflection device and the second deflection device is one of:
the voltages applied to the first deflection device and the second deflection device are alternating voltages;
the voltage applied to the first deflection device is alternating voltage, and the voltage applied to the second deflection device is constant voltage; wherein the voltage range value of the constant voltage is-5 kV to 5kV;
the voltage applied to the first deflection device is alternating voltage, and the voltage applied to the second deflection device is the superposition voltage of a constant voltage and a constant deflection voltage.
9. The method according to claim 7 or 8, characterized in that the method further comprises: and after the electric lens reversely accelerates the signal electrons generated by the electron beam acting on the sample to be detected and changes the movement direction of the signal electrons, the signal electrons are received by the detection device.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310084443.2A CN116190184A (en) | 2023-01-18 | 2023-01-18 | Scanning electron microscope objective lens system and scanning focusing method |
| PCT/CN2023/124704 WO2024083068A1 (en) | 2023-01-18 | 2023-10-16 | Objective lens system for scanning electron microscope, and scanning focusing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310084443.2A CN116190184A (en) | 2023-01-18 | 2023-01-18 | Scanning electron microscope objective lens system and scanning focusing method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116190184A true CN116190184A (en) | 2023-05-30 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310084443.2A Pending CN116190184A (en) | 2023-01-18 | 2023-01-18 | Scanning electron microscope objective lens system and scanning focusing method |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN116190184A (en) |
| WO (1) | WO2024083068A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116646228A (en) * | 2023-07-20 | 2023-08-25 | 北京惠然肯来科技中心(有限合伙) | Fast focusing scanning deflection device and scanning electron microscope |
-
2023
- 2023-01-18 CN CN202310084443.2A patent/CN116190184A/en active Pending
- 2023-10-16 WO PCT/CN2023/124704 patent/WO2024083068A1/en unknown
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116646228A (en) * | 2023-07-20 | 2023-08-25 | 北京惠然肯来科技中心(有限合伙) | Fast focusing scanning deflection device and scanning electron microscope |
| CN116646228B (en) * | 2023-07-20 | 2023-10-27 | 北京惠然肯来科技中心(有限合伙) | Fast focusing scanning deflection device and scanning electron microscope |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2024083068A1 (en) | 2024-04-25 |
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