JP6550478B2 - Multi-beam apparatus, charged particle beam apparatus, source conversion unit, method of constructing source conversion unit, method for forming virtual multi-source array - Google Patents

Description

This application claims priority to U.S. Provisional Application No. 62 / 130,819 entitled "Devices for Multiple Charged Particle Beams", the subject of Ren et al., Filed March 10, 2015. , Which is incorporated herein by reference in its entirety.

  The present invention relates to a charged particle device having a plurality of charged particle beams, and more particularly to a device using a plurality of charged particle beams to simultaneously acquire images of a plurality of scan areas of an observation area on a sample surface. Thus, the apparatus can be used to inspect and / or investigate defects on wafers / masks with high resolution and high throughput in the semiconductor manufacturing industry.

  In the manufacture of semiconductor IC chips, pattern defects and / or uninvited particles (residues) inevitably appear on the surface of the wafer / mask during the manufacturing process, which greatly reduces the yield. In order to meet the performance requirements of the increasingly evolving IC chips, patterns with smaller and smaller critical feature dimensions are being adopted. Thus, conventional yield control tools that use optical beams are gradually becoming ineligible due to diffraction effects, and yield control tools that use electron beams are increasingly used. Compared to photon beams, electron beams can provide excellent spatial resolution due to their short wavelength. Currently, yield management tools that use electron beams use scanning electron microscope (SEM) principles that use a single electron beam, so they can provide high resolution but can not provide throughput suitable for mass production. While it is possible to use increasingly larger beam currents to increase throughput, good spatial resolution is basically degraded by the coulomb effect.

  A promising solution that does not use a single electron beam with a large current to alleviate the constraints on throughput is to use multiple electron beams, each with a small current. A plurality of electron beams form a plurality of probe spots on one inspected or observed surface of the sample. On the sample surface, a plurality of probe spots can simultaneously scan a plurality of small scan areas within a large observation area on the sample surface. The electrons of each probe spot generate secondary electrons from the incident place on the sample surface. The secondary electrons include slow secondary electrons (energy of 50 eV or less) and backscattered electrons (energy close to the energy of incident electrons). Secondary electrons from multiple small scan areas can be simultaneously collected by multiple electron detectors, respectively. Thus, an image of a large viewing area that includes all the small scan areas can be obtained much faster than scanning the large viewing area with a single beam.

  The plurality of electron beams may be obtained respectively from a plurality of electron sources or from a single electron source. In the former, multiple electron beams are usually focused and scanned respectively by multiple columns into multiple small scan areas, and secondary electrons from each scan area are detected by one electron detector inside the corresponding column Ru. Thus, this device is generally referred to as a multi-column device. Multiple columns can be independent or share a multi-axis magnetic or electromagnetic complex objective (eg US 8, 294, 095). The beam spacing of two adjacent beams on the sample surface is usually of the order of 30 to 50 mm.

  In the latter, a source conversion unit is used to virtually transform a single electron source into multiple sub-sources. The source conversion unit comprises one beamlet forming means and one image forming means. The beamlet forming means basically comprises a plurality of beam limiting apertures which respectively split the primary electron beam generated by the single electron source into a plurality of sub-beams or beamlets. The imaging means basically comprise a plurality of electro-optical elements which either converge or deflect respectively on a plurality of beamlets so as to form a plurality of parallel images of the electron source. Each of the plurality of parallel images can be regarded as one sub-source emitting one corresponding beamlet. Because the beamlet spacing or beam limiting aperture spacing is on the order of micrometers, more beamlets are available, so the source conversion unit can be fabricated by semiconductor manufacturing process or MEMS (micro-electromechanical system) process . Of course, one primary projection imaging system and one deflection scanning unit in one single column are used to project and scan multiple parallel images onto multiple small scan areas, respectively. The plurality of secondary electron beams to be detected are respectively detected by the plurality of detection elements of one electron detection device inside the single column. The plurality of detection elements may be a plurality of electron detectors arranged in parallel, or a plurality of pixels of one electron detector. Thus, this device is generally referred to as a multi-beam device.

  In the source conversion unit 20-1 of FIG. 1A, the image forming unit 22-1 includes a plurality of lenses (22_1L to 22_3L). The substantially parallel primary electron beam 2 from one single electron source is divided into a plurality of beamlets (2_1 to 2_3) by a plurality of beam limiting apertures (21_1 to 21_3) of the beamlet forming means 21, The lens of each converges the plurality of beamlets to form a plurality of parallel images (2_1r to 2_3r) of a single electron source. The multiple parallel images are typically real images, but may be virtual images in certain conditions where each of the multiple lenses is an aperture lens. US 7,244,949 and US 7,880,143 propose a multi-beam apparatus with one imaging means of this type. In the source conversion unit 20-2 of FIG. 1B, the image forming means 22-2 comprises a plurality of deflectors (22_2D and 22_3D). The divergent primary electron beam 2 from one single electron source is divided into a plurality of beamlets (2_2 and 2_3) by a plurality of beam limiting apertures (21_2 and 21_3) of the beamlet forming means 21 and a plurality of deflectors are single The plurality of beamlets are respectively deflected to form a plurality of parallel virtual images (2_2v and 2_3v) of an electron source.

  The idea of using a deflector to form a virtual image of an electron source was used for the famous double slit electron interference experiments as early as the 1950s. Here, as shown in Fig. 2 (Fig. 1 of "Merli-Misciroli Podge's double slit electron interference experiment", Physics in perspective, 14 (2012), published in 178 to 195, by Rodolfo Rosa) An electron biprism is used to form two virtual images. The electron biprism basically comprises two parallel plates at ground potential and a very thin wire F between them. When a potential not equal to ground potential is applied to the wire F, the electron biprism will be two deflectors with deflections in opposite directions. The primary electron beam from the electron source S passes through the two deflectors into two deflected beamlets which form virtual images S1 and S2 of the electron source S. If the potential is positive, the two beamlets overlap each other and interference fringes appear in the overlapping area.

  Since then, the above mentioned idea has been used in many ways in multi-beam devices. JP-A-10-339711 and US Pat. No. 8,378,299 use one conventional electron biprism directly to form two probe spots on the sample surface. US 6,943,349 uses one annular deflector (FIG. 5 of the same document) or one corresponding deflector array (FIG. 12 of the same document) to form more than two probe spots on the sample surface And thereby provide high throughput. The annular deflector includes an inner annular electrode and an outer annular electrode. If the potentials of the two annular electrodes are not equal to one another, an electric field appears in the annular gap locally in the radial direction, so that the annular deflector deflects more than two beamlets together in different directions be able to. Furthermore, the deflection function of the annular deflector can also be performed by one corresponding deflector array having a plurality of multipole deflectors arranged along the annular gap.

  In the conventional source conversion unit 20-2 of FIG. 1B, due to the divergence of the primary electron beam 2, a plurality of beamlets pass through a plurality of beam limiting apertures at different incident angles, thereby varying the intensity of electrons I am bothered by the scattering. The scattered electrons in each beamlet enlarge the probe spot and / or become background noise, thus degrading the image resolution of the corresponding scan area.

  In US 6,943,349, the current of multiple beamlets can only be deflected by changing either the emission of a single electron source or the size of the beam limiting aperture. A single electron source takes a long time to become stable when its emission rate is changed. The beamlet forming means needs to have a plurality of groups of apertures and to make the size of the aperture of one group different from the other groups. Changing groups at the time of use is very time consuming. In addition, the secondary electron beam can only be focused on the multiple detection elements of the in-lens detector at some specific operating conditions of the objective. This limits the available application areas.

  Therefore, it is necessary to provide a multi-beam apparatus capable of simultaneously acquiring images of a plurality of small scan areas in a large observation area on a sample surface with high resolution and high throughput. In particular, a multi-beam system capable of inspecting and / or investigating defects on wafers / masks with high resolution and high throughput is needed to meet the roadmap for the semiconductor manufacturing industry.

  The object of the present invention is to provide both high resolution and high throughput for observing samples, in particular as a yield management tool for inspecting and / or investigating defects on wafers / masks in the semiconductor manufacturing industry To provide a novel multi-beam apparatus. The multi-beam apparatus first forms a plurality of parallel virtual images of a single electron source, and then a new source conversion unit to limit the current of the corresponding plurality of beamlets, and the current of the plurality of beamlets. Condenser lens for adjustment, primary projection imaging system for projecting a plurality of parallel virtual images so as to form a plurality of probe spots on a surface to be observed of a sample, a plurality of beams of a plurality of secondary electron beams from the surface A beam separator deflecting out of the path of the let and a secondary projection imaging system focusing a plurality of secondary electron beams as detected by a plurality of detection elements of the electron detection device are employed.

  Thus, the present invention provides a source conversion unit, which comprises an imaging means comprising an upper layer having a plurality of upper quadrupole structures and a lower layer having a plurality of lower quadrupole structures, and a lower portion of the imaging means. And beamlet limiting means comprising a plurality of beam limiting apertures. Each upper quadrupole structure is above and aligned with one corresponding lower quadrupole structure, both of which differ in azimuth by 45 ° and form a set of quadrupole structures. Thus, the plurality of upper 4-pole structures and the plurality of lower 4-pole structures form a set of plurality of 4-pole structures. The plurality of beam limiting apertures are respectively aligned with the plurality of sets of quadrupolar structures. A set of one quadrupole structure is a micro deflector for deflecting one beamlet of the electron beam generated by the electron source to form a virtual image of the electron source, a microlens for focusing one beamlet to a desired degree, And / or functions as a micro-stig meter which adds a desired amount of astigmatism to one beamlet.

  The invention also provides a multi-beam apparatus for observing the surface of a sample, which comprises an electron source, a condenser lens below the electron source, a source conversion unit below the condenser lens, and the source Below the conversion unit, a primary projection imaging system with an objective lens, a deflection scanning unit inside the primary projection imaging system, a sample stage below the primary projection imaging system, above the objective lens A beam separator, a secondary projection imaging system above the beam separator, and an electronic detection device having a plurality of detection elements. The source conversion unit comprises an imaging means having a plurality of micro-deflectors and a beamlet limiting means having a plurality of beam limiting apertures, the imaging means being above the beamlet limiting means. The electron source, the condenser lens, the source conversion unit, the primary projection imaging system, the deflection scanning unit and the beam separator are aligned with the primary optical axis of the device. The sample stage supports the sample such that the surface faces the objective lens. The secondary projection imaging system and the electronic detection device are aligned with the secondary optical axis of the apparatus, the secondary optical axis being non-parallel to the primary optical axis. The electron source produces a primary electron beam along a primary optical axis, and the plurality of micro deflectors deflect the primary electron beam to form a plurality of parallel virtual images of the electron source. A virtual multi-source array is thereby transformed from the electron source, and a plurality of beamlets comprising the virtual multi-source array pass through the plurality of beam limiting apertures respectively. The current of each beamlet is thereby limited by one corresponding beam limiting aperture, and the current of multiple beamlets can be varied by adjusting the condenser lens. A primary projection imaging system images a virtual multi-source array onto a surface, whereby a plurality of probe spots are formed on the surface. The deflection scanning unit deflects the plurality of beamlets to cause the plurality of scanning areas in the observation area on the surface to scan the plurality of probe spots respectively. A plurality of secondary electron beams are respectively generated from the plurality of scan areas by the plurality of probe spots and are converged as they pass through the objective lens. The beam separator deflects the plurality of secondary electron beams into the secondary projection imaging system, and the secondary projection imaging system focuses the plurality of secondary electron beams to be detected by the plurality of detection elements, respectively. And maintain. Each detector element thereby provides an image signal of one corresponding scan area.

  The multi-beam device may further comprise a main aperture plate below the electron source and having a main aperture aligned with the primary optical axis and acting as a beam limiting aperture for the primary electron beam. The primary projection imaging system may comprise a transfer lens above the objective and focusing the plurality of beamlets so as to be perpendicularly incident on the surface. Each of the plurality of micro deflectors has a four-pole structure capable of generating a deflection field in any radial direction. The multi-beam apparatus may further comprise a single beam electron detector above the beam separator and usable in single beam mode. The multi-beam device may further comprise an in-lens electron detector with beamlet passage holes aligned with the primary optical axis, below the beam separator and usable in single beam mode.

  The invention also provides a multi-beam apparatus for observing the surface of a sample, which comprises an electron source, a condenser lens below the electron source, a source conversion unit below the condenser lens, and the source Below the conversion unit, a primary projection imaging system with an objective lens, a deflection scanning unit inside the primary projection imaging system, a sample stage below the primary projection imaging system, above the objective lens A beam separator, a secondary projection imaging system above the beam separator, and an electronic detection device having a plurality of detection elements. The source conversion unit comprises an imaging means comprising a plurality of micro deflector compensator elements and a beamlet limiting means comprising a plurality of beam limiting apertures, each micro deflector compensator element comprising one micro deflector and one micro deflector. And one micro compensator with one micro stig meter. The imaging means are above the beamlet limiting means. The electron source, the condenser lens, the source conversion unit, the primary projection imaging system, the deflection scanning unit and the beam separator are aligned with the primary optical axis of the device. The sample stage supports the sample such that the surface faces the objective lens. The secondary projection imaging system and the electronic detection device are aligned with the secondary optical axis of the apparatus, the secondary optical axis being non-parallel to the primary optical axis. The electron source produces a primary electron beam along a primary optical axis, and the plurality of micro deflectors deflect the primary electron beam to form a plurality of parallel virtual images of the electron source. A virtual multi-source array is thereby transformed from the electron source. A plurality of beamlets, including a virtual multi-source array, respectively pass through the plurality of beam limiting apertures, whereby the current of each beamlet is limited by one corresponding beam limiting aperture. The current of multiple beamlets can be changed by adjusting the condenser lens. A primary projection imaging system images a virtual multi-source array onto a surface, whereby a plurality of probe spots are formed on the surface. One micro-compensator micro-lens and one micro-stig-meter compensate the field curvature and astigmatism of one corresponding probe spot respectively, the deflection scanning unit The plurality of beamlets are deflected so that the scanning region is scanned by the plurality of probe spots respectively. A plurality of secondary electron beams are respectively generated from the plurality of scanning areas by the plurality of probe spots and are converged as they pass through the objective lens, and the beam separator is arranged to be incident on the secondary projection imaging system Of the secondary electron beam. The secondary projection imaging system focuses and maintains the plurality of secondary electron beams to be respectively detected by the plurality of detection elements, whereby each detection element provides an image signal of one corresponding scan area .

  The multi-beam device may further comprise a main aperture plate below the electron source and having a main aperture aligned with the primary optical axis and acting as a beam limiting aperture for the primary electron beam. Each of the plurality of micro deflector compensator elements is formed as a single micro deflector by generating a desired deflection field, and as a single micro compensator by generating a desired quadrupole field and a desired circular lens field. It may have a functional eight pole structure. Each of the plurality of micro deflector compensator elements has an upper quadrupole structure in the upper layer and a lower quadrupole structure in the lower layer, the upper layer being above the lower layer, the upper quadrupole structure and the lower quadrupole The structures are aligned with one another and differ in azimuth by 45 °. Upper quadrupole structure and lower quadrupole structure as one micro deflector by generating the desired deflection field and as one micro compensator by generating the desired quadrupole field and the desired circular lens field It may function. The primary projection imaging system may comprise a transfer lens above the objective and focusing the plurality of beamlets so as to be perpendicularly incident on the surface. The multi-beam apparatus may further comprise a single beam electron detector above the beam separator and usable in single beam mode. The multi-beam device may further comprise an in-lens electron detector with beamlet passage holes aligned with the primary optical axis, below the beam separator and usable in single beam mode.

  The present invention also provides a method of constructing a source conversion unit for forming a virtual multi-source array from electron sources, which comprises an upper layer having a plurality of upper quadrupole structures and a plurality of lower quadrupole structures. Providing an imaging means comprising a bottom layer comprising: and providing a beamlet limiting means below the imaging means and comprising a plurality of beam limiting apertures. Each upper quadrupole structure is above and aligned with one corresponding lower quadrupole structure, both of which differ in azimuth by 45 ° and form a set of quadrupole structures. Thereby, the plurality of upper 4-pole structures and the plurality of lower 4-pole structures form a plurality of sets of 4-pole structures. The plurality of beam limiting apertures are respectively aligned with the plurality of sets of quadrupolar structures. A microdeflector deflects one beamlet of an electron beam generated by an electron source to form a virtual image of the electron source, and a microdeflects one beamlet to a desired degree. It functions as a lens and / or a micro-stigometer that adds a desired amount of astigmatism to the one beamlet.

  The source conversion unit may comprise an upper electrically conductive plate having a plurality of upper through holes respectively aligned with a plurality of quadrupolar structure sets. The source conversion unit may further comprise a lower electrically conductive plate having a plurality of lower through holes respectively aligned with the plurality of quadrupolar structure sets.

  The invention also provides a method for forming a virtual multi-source array from an electron source, which uses a top layer having a plurality of top quadrupole structures and a bottom layer having a plurality of bottom quadrupole structures. Deflecting the electron beam from the electron source into a plurality of beamlets, and limiting the plurality of beamlets by using a plurality of apertures. Each upper quadrupole structure is above and aligned with one corresponding lower quadrupole structure, both of which differ in azimuth by 45 ° and form a set of quadrupole structures.

  The present invention also provides a charged particle beam device, which comprises a single charged particle source providing a primary beam, means for converting the primary beam into a plurality of beamlets, and a plurality of beamlets on the specimen. A first projection system for forming a plurality of probe spots, a deflection scanning unit for scanning a plurality of probe spots on a specimen, a means for separating a plurality of signal electron beams from a plurality of beamlets, and a plurality of signal electron beams And a second projection system for forming a plurality of signal spots from a plurality of signal electron beams respectively on a plurality of electron detection elements of the detection device. The transforming means comprises a plurality of deflectors for deflecting a plurality of beamlets and a plurality of beam limiting apertures below the plurality of deflectors. The plurality of signal electron beams are respectively generated by the collision of the plurality of beamlets on the sample.

  The charged particle beam device may further comprise a condenser lens that regulates the current of the plurality of probe spots. The conversion means comprises a plurality of compensators which respectively compensate for the aberrations of the plurality of probe spots.

  Other advantages of the present invention will be apparent from the accompanying drawings and the following description which illustrate several embodiments of the present invention for purposes of illustration.

  The present invention will be readily understood by the following drawings and the following detailed description. Like reference symbols in the various drawings indicate like structural elements.

FIG. 1 is a schematic view of a conventional source conversion unit. FIG. 1 is a schematic view of a conventional source conversion unit.

It is the schematic of the electron interference experiment which used the electron beam biprism.

FIG. 1 is a schematic view of one configuration of a new multi-beam device according to an embodiment of the present invention.

FIG. 3B is a schematic view of the mode of operation of the new multi-beam device of FIG. 3A. FIG. 3B is a schematic view of the mode of operation of the new multi-beam device of FIG. 3A. FIG. 3B is a schematic view of the mode of operation of the new multi-beam device of FIG. 3A.

FIG. 7 is a schematic view of another configuration of the new multi-beam apparatus according to another embodiment of the present invention.

FIG. 3C is a schematic view of the configuration of the imaging means of FIG. 3A according to another embodiment of the present invention. FIG. 3C is a schematic view of the configuration of the imaging means of FIG. 3A according to another embodiment of the present invention. FIG. 3C is a schematic view of the configuration of the imaging means of FIG. 3A according to another embodiment of the present invention.

FIG. 3C is a schematic view of the configuration of the imaging means of FIG. 3A according to another embodiment of the present invention. FIG. 3C is a schematic view of the configuration of the imaging means of FIG. 3A according to another embodiment of the present invention. FIG. 3C is a schematic view of the configuration of the imaging means of FIG. 3A according to another embodiment of the present invention. FIG. 3C is a schematic view of the configuration of the imaging means of FIG. 3A according to another embodiment of the present invention.

FIG. 5 is a schematic view of the configuration of the advanced imaging means of FIG. 4 according to another embodiment of the present invention.

FIG. 5 is a schematic view of the configuration of the advanced imaging means of FIG. 4 according to another embodiment of the present invention. FIG. 5 is a schematic view of the configuration of the advanced imaging means of FIG. 4 according to another embodiment of the present invention. FIG. 5 is a schematic view of the configuration of the advanced imaging means of FIG. 4 according to another embodiment of the present invention. FIG. 5 is a schematic view of the configuration of the advanced imaging means of FIG. 4 according to another embodiment of the present invention.

FIG. 7 is a schematic view of another configuration of the new multi-beam apparatus according to another embodiment of the present invention.

FIG. 9B is a schematic view of the mode of operation of the new multi-beam device of FIG. 9A. FIG. 9B is a schematic view of the mode of operation of the new multi-beam device of FIG. 9A.

FIG. 5 is a schematic view of one mode of operation of the new multi-beam device of FIG. 4;

FIG. 7 is a schematic view of another configuration of the new multi-beam device according to another embodiment of the present invention and its one operation mode.

FIG. 7 is a schematic view of another configuration of the new multi-beam device according to another embodiment of the present invention and its one operation mode.

  Various exemplary embodiments of the present invention will be described more fully hereinafter with reference to the accompanying drawings, in which some exemplary embodiments of the present invention are shown. Without limiting the scope of protection of the present invention, all of the description of the embodiments and the drawings refer to electron beams by way of example, but the embodiments are used to limit the present invention to specific charged particles You should not.

  In the drawings, the components and the relative dimensions between the components may be exaggerated for clarity. In the following description of the drawings, the same or similar reference numbers refer to the same or similar components or entities, and only differences with regard to the individual embodiments are described. For clarity, only three beamlets are available in the drawing, but any number of beamlets may be used.

  Accordingly, while example embodiments of the present invention are capable of various modifications and alternative forms, embodiments thereof are shown by way of example in the drawings and will herein be described in detail. However, there is no intention to limit the illustrative embodiments of the present invention to the particular forms disclosed, and in contrast, the illustrative embodiments of the present invention include any and all variations that fall within the scope of the present invention. , Equivalents, and alternatives.

  In the present invention, “axial direction” means “optical axis direction of lens (circular or multipolar), imaging system or apparatus”, and “radial direction” means “direction perpendicular to optical axis”. No, "on-axis" means "on the optical axis or aligned with the optical axis", and "off-axis" means "not on the optical axis or aligned with the optical axis" "No".

  In the present invention, "the imaging system is aligned with the optical axis" means that "all electron optical elements (circular lens, multipole lens, etc.) are aligned with the optical axis".

  In the present invention, the X, Y and Z axes form a Cartesian coordinate system. The optical axis of the primary projection imaging system is on the Z-axis, and the primary electron beam travels along the Z-axis.

  In the present invention, "primary electrons" means "electrons emitted from an electron source and incident on the observed or inspected surface of a sample", and "secondary electrons" means "primary electrons from the surface" "Electrons generated by

  In the present invention, "signal electrons" refer to "electrons generated by the primary charged particle beam from the observed or inspected surface of the sample".

  In the present invention, "single beam mode" means that only one beamlet is used.

  In the present invention, all terms related to through holes, openings, and orifices refer to openings or holes through one plate.

  Subsequently, the invention provides several embodiments of the new multi-beam apparatus. In a multi-beam device, the multi-beam device first forms a plurality of parallel virtual images of a single electron source, and then a new source conversion unit that limits the current of the plurality of beamlets, and the plurality of beamlets And a primary projection imaging system for projecting a plurality of parallel virtual images to form a plurality of probe spots on a surface to be observed of the sample, and a plurality of secondary electron beams from the surface. A beam separator for deflecting out of the paths of the plurality of beamlets, and a secondary projection imaging system for focusing the plurality of secondary electron beams to be respectively detected by the plurality of detection elements of the electron detection device; adopt.

  The new source conversion unit comprises an imaging means having a plurality of micro deflectors and a beamlet limiting means having a plurality of beam limiting apertures, the imaging means being upstream of the beamlet limiting means. The primary electron beam from the single electron source is first deflected by the plurality of micro deflectors to form a plurality of parallel virtual images of the single electron source, and a plurality of beams forming a plurality of parallel virtual images The let passes through the plurality of beam limits vertically or substantially vertically. In this way, the plurality of beam limiting apertures not only produce electrons with lower scattering compared to the prior art, but also block upstream generated scattered electrons, thus degrading the image resolution due to electron scattering There is no The imaging means further comprise a plurality of micro-compensators respectively compensating for off-axis aberrations (field curvature and astigmatism) of the plurality of probe spots, thus further improving the image resolution of the surface to be observed.

  FIG. 3A illustrates one embodiment 100A of the new multi-beam device. The single electron source 101 is on the primary optical axis 100_1. The common condenser lens 110, the main aperture plate 171, the new source conversion unit 120, the primary projection imaging system 130, the deflection scanning unit 132, and the beam separator 160 are disposed along the primary optical axis 100_1 and the primary optical axis It is aligned to 100_1. The secondary projection imaging system 150 and the electronic detection device 140 are disposed along the secondary optical axis 150_1 and aligned with the secondary optical axis 150_1.

  The main aperture plate 171 can be disposed above the common condenser lens 9 or directly above the new source conversion unit 120 as shown. The new source conversion unit 120 comprises a micro deflector array 122 with two micro deflectors 122_2, 122_3 and a beamlet limiting plate 121 with three beam limiting apertures 121_1, 121_2, 121-3, the beam limiting aperture 121_1 are aligned with the primary optical axis 100_1. If the beam limiting aperture 121_1 is not aligned with the primary optical axis 100_1, there may be another micro deflector 122_1 (as shown in FIG. 5C). The primary projection imaging system 130 comprises a transfer lens 133 and an objective lens 131. The deflection scanning unit 132 comprises at least one deflector. The beam separator 160 is a Wien filter. The secondary projection imaging system 150 comprises a reverse scanning deflector 151, a zoom lens 152 (comprising at least two lenses 152_1, 152_2), and a reverse rotating magnetic lens 154. The electronic detection device 140 comprises three detection elements 140_1, 140_2, 140_3. Each of the lenses described above may be an electrostatic lens, a magnetic lens, or an electromagnetic complex lens.

  3B-3D illustrate three operating modes of the new multi-beam device 100A. The single electron source 101 includes a cathode, an extraction portion, and / or an anode, and primary electrons are emitted from the cathode to provide high energy (eg, 8 to 20 keV) and high angular intensity (eg, 0.5 to 5 mA / sr). And the primary electron beam 102 is crossed and / or accelerated to form a primary electron beam 102 having an imaginary or real crossover 101s (illustrated by the on-axis elliptical symbol), and thus the primary electron beam 102 is crossed. It is convenient to think that emanating from over 101s and simplifying the single electron source 101 as crossover 101s.

  In FIG. 3B, the condenser lens 110 is off. The primary electron beam 102 passes through the condenser lens 110 without the influence of convergence, and the electrons at its periphery are blocked by the main aperture of the main aperture plate 171. The micro deflectors 122_2 and 122_3 deflect the beamlets 102_2 and 102_3 of the primary electron beam 102, respectively. The deflected beamlets 102_2 and 102_3 form off-axis virtual images 102_2v and 102_3v of the crossover 101s of the single electron source 101, respectively. The deflected beamlets 102_2, 102_3 are parallel or substantially parallel to the primary optical axis 100_1 and thus perpendicularly incident on the beamlet limiting plate 121. The beam limiting apertures 121_1, 121_2, 121_3 block electrons at the periphery of the central portion 102_1 of the primary electron beam 102 and the deflected beamlets 102_2, 102_3, respectively. As a result, one virtual multi-source array 101v is formed, which includes the crossover 101s and its two parallel off-axis virtual images 102_2v and 102_3v. One virtual image can avoid the Coulomb effect in one real image in FIG. In order to further reduce the Coulomb effect, the main aperture plate 171 may be placed above the condenser lens 110 so as to block the peripheral electrons as early as possible.

  Subsequently, the crossover 101s and its two parallel off-axis virtual images 102_2v, 102_3v are imaged by the transfer lens 133 and the objective lens 131 onto the surface 7 to be observed, and these images are there at the three probe spots 102_1s , 102_2s, 102_3s. In order for the two off-axis beamlets 102_2, 102_3 to be perpendicularly incident on the surface 7 to be observed, the transfer lens 133 focuses them so as to pass through the front focal point of the objective lens 131. If the objective lens 131 comprises one magnetic lens, the two off-axis beamlets 102_2, 102_3 may not pass through the front focus precisely due to the influence of the magnetic rotation, which is a beamlet crossover Very useful for reducing the coulomb effect in CS. The deflection scanning unit 132 deflects the three beamlets 102_1 to 102_3 so that the three probe spots 102_1s to 102_3s scan three separate areas on the surface 7 to be observed.

  Secondary electron beams 102_1se, 102_2se, 102_3se emitted from the three scanning regions are focused by the objective lens 131 and enter the secondary projection imaging system 150 along the secondary optical axis 150_1 by the beam separator 160 It is biased to The lenses 152 and 153 focus the secondary electron beam on the three detection elements 140_1 to 140_3, respectively. Each detection element thereby provides an image signal of one corresponding scan area. When part of secondary electrons of the secondary electron beam from one scan area is directed to an adjacent detection element, the image signal of the adjacent detection element contains irrelevant information from the scan area and the adjacent ones The irrelevant information for the detecting element is crosstalk from the scanning area. In order to avoid cross-talk between the detector elements, the zoom lens 152 makes the spot size of each secondary electron beam smaller than the corresponding detector elements, and the reverse scanning deflector 151 makes it possible for the deflection scanning unit 132 to have the beamlets 102_1-102_3. , And synchronously deflect the secondary electron beams 102_1se to 102_3se so as to be maintained in the corresponding detection elements.

  Different samples usually require different viewing conditions such as beamlet incident energy and current. This is particularly the case for inspection and / or investigation of wafer / mask defects in the semiconductor manufacturing industry. The focusing power of the objective lens 131 changes with incident energy, which affects the position of the secondary electron beam on the electron detection device 140, causing crosstalk. In this case, the zoom lens 152 is adjusted to remove the radial displacement of the secondary electron beam. If the objective lens 131 comprises one magnetic lens, the counter-rotating magnetic lens 154 is adjusted to eliminate the rotation of the secondary electron beam.

  Each of the two off-axis probe spots 102_2s, 102_3s comprises off-axis aberrations produced by the objective lens 131, the transfer lens 133 and the condenser lens when turned on. The off-axis aberrations of each off-axis probe spot can be reduced by optimizing the corresponding beamlet trajectories individually. The static part of the off-axis aberration can be reduced by adjusting the deflection force of the corresponding micro deflector. The dynamic part of the off-axis aberration can be reduced by optimizing the performance of the deflection scanning unit 132. To that end, the deflection scanning unit 132 may be equipped with a plurality of deflectors.

  Unlike FIG. 3B, the condenser lens 110 is switched on in FIG. 3C. Condenser lens 110 focuses primary electron beam 102 to form on-axis virtual image 101 sv of crossover 101 s of single electron source 101. The micro deflectors 122_2 and 122_3 respectively deflect the beamlets 102_2 and 102_3 of the converged primary electron beam 102 to form off-axis virtual images 102_2v and 102_3v of the crossover 101s. The deflected beamlets 102_2, 102_3 are parallel or substantially parallel to the primary optical axis 100_1 and thus perpendicularly incident on the beamlet limiting plate 121. The beam limiting apertures 121_1, 121_2, 121_3 respectively block electrons at the periphery of the central portion 102_1 of the focused primary electron beam 102 and the deflected beamlet 102_2, 102_3, thereby limiting their current. The focusing function of the condenser lens 110 increases the current density of the focused primary electron beam 102, thereby increasing the current of the beamlets 102_1-102_3 higher than in FIG. 3B. Thus, the current of all beamlets can be continuously adjusted by the condenser lens 110.

  As with conventional SEM, the size of each probe spot is minimized by balancing geometric aberration, diffraction aberration, Gaussian image size, and Coulomb effect. The focusing function of the condenser lens 110 changes the imaging magnification from the crossover 101s to the surface 7 to be observed, which affects the above balance, so the size of each probe spot can be increased. The size of the beam limiting apertures 121_1-121_3 may be varied considerably to avoid a large increase in the size of the probe spot when making a large change in the current of the beamlet. As a result, the beamlet limiting plate 121 preferably comprises multiple groups of beam limiting apertures. The size of the beam limiting aperture in one group is different from that of the other group. Alternatively, the converging power of the transfer lens 133 may be changed to reduce the variation of the imaging magnification. Since the trajectories of the off-axis beamlets 102_2, 102_3 are affected by the focusing force fluctuations of the transfer lens 133, considerable adjustments may be made to the deflection forces so that the deflection forces of the micro deflectors 122_2, 122_3 maintain the trajectories . Thus, the beamlets 102_2, 102_3 may be slightly non-parallel to the primary optical axis 100_1, as shown in FIG. 3D.

  FIG. 4 shows another embodiment 110A of the new multi-beam device. Unlike the embodiment 100A, the new source conversion unit 120-1 comprises a micro deflector compensator array 122-1 having three micro deflector compensator elements 122_1dc, 122_2dc, 122_3dc. Each micro deflector compensator element comprises one micro deflector and one micro compensator with one micro lens and one micro stig meter. Micro-deflectors are used to form one virtual multi-source array, similar to the functions of micro-deflectors 122_2, 122_3 shown in FIGS. 3B-3D. As is well known, the condenser lens 110, the transfer lens 133, and the objective lens 131 generate off-axis aberrations. As mentioned above, the effect of off-axis aberrations on the size of the probe spot can be reduced by optimizing the beamlet trajectories individually. Therefore, a micro lens and a micro stig meter are used to compensate for the curvature of field and astigmatism remaining in the probe spot, respectively. Compared to the micro deflector array 122 of FIG. 3A, the micro deflector compensator array 122-1 is an advanced imaging means.

  Each of the micro-deflectors 122_2, 122_3 of FIG. 3A may simply include two parallel electrodes perpendicular to the required deflection direction of the corresponding beamlet, as shown in FIG. 5A. For example, the micro deflector 122_2 has two parallel electrodes 122_2_e1 and 122-2_e2 perpendicular to the X axis, thereby deflecting the beamlet 102_2 in the X axis direction. FIG. 5B illustrates one embodiment of a micro deflector array 122 that deflects eight beamlets. Because each micro-deflector has a spatial orientation, it is difficult to make one micro-deflector array 122 with multiple micro-deflectors. From a manufacturing point of view, it is desirable that all micro-deflectors have the same geometrical configuration and posture. Therefore, a micro deflector with a quadrupole or quadrupolar configuration can meet this requirement, as shown in FIG. 5C. The four electrodes of each micro-deflector can form two deflectors that can deflect one beamlet in any direction. The micro deflector 122_1 can be used when the corresponding beam limiting aperture 121_1 is not exactly aligned with the primary optical axis 101.

  In order to operate one micro deflector, a drive circuit needs a connection with each of its electrodes. In order to prevent the drive circuit from being damaged by the primary electron beam 102, it is preferable to place one electrically conductive plate above the electrodes of all the micro deflectors of FIGS. 5A-5C. Taking FIG. 5C as an example, FIG. 6 shows the upper electrically conductive plate 122-CL1 having a large number of upper through holes and the upper insulator plate 122-IL1 having a large number of upper orifices, of the electrodes of the micro deflectors 122_1 to 122_3. It is located at the top. The electrodes of the micro deflectors 122_1 to 122_3 can be attached to the upper insulator plate 122-IL1. The upper through hole and the upper orifice are respectively aligned with the optical axis of the micro deflector, for example, the upper through hole CL1_2 and the upper orifice IL1_2 are on the optical axis 122_2_1 of the micro deflector 122_2. The radial size of each upper through hole is equal to or smaller than the inner diameter dimension of the corresponding micro deflector electrode to protect the drive circuit, and the radial size of each upper orifice avoids charging of the inner side wall And the radial size of the corresponding upper through hole. In this way, deflection aberrations are reduced, since the deflection field of all micro deflectors has a shorter edge range on its upper side.

  Based on FIG. 6A, the micro deflector array 122 of FIG. 6B further comprises a lower electrically conductive plate 122-CL2 having a plurality of lower through holes. Each lower through hole is aligned with the optical axis of one micro deflector, for example, the lower through hole CL2_2 is on the optical axis 122_2_1 of the micro deflector 122_2. In this way, deflection aberrations are reduced, since the deflection fields of all micro deflectors have a shorter edge range on both the upper and lower sides. Unlike FIG. 6B, the micro-deflector array 122 of FIG. 6C employs a lower insulator plate 122-IL2 having a number of lower orifices to support the electrodes of the micro-deflectors 122_1-122_3. Each lower orifice is aligned with the optical axis of one micro deflector, for example, the lower orifice IL2_2 is on the optical axis 122_2_1 of the micro deflector 122_2. The radial size of each lower orifice is larger than the inner diameter dimension of the corresponding micro deflector electrode. The micro deflector array 122 of FIG. 6D is a combination of FIGS. 6B and 6C, resulting in a more stable configuration.

  FIG. 7 illustrates one embodiment of the micro deflector compensator element 122_2dc of the micro deflector compensator array 122-1 of FIG. 4, which has an eight pole configuration. Eight electrodes 122_2dc_e1 to 122_2dc_e8 have a basic amount for generating a virtual image of the electron source 1 in any direction and a dipole field (deflection field) having an addition amount for correcting distortion, and four for correcting astigmatism in any direction. It can be driven to generate a quadrupole field (astigmatism field) and a circular lens field that corrects the field curvature.

  FIG. 8A shows another embodiment of the micro deflector compensator array 122-1 of FIG. Each micro-deflector compensator element comprises a set of four-pole lenses arranged in two layers, aligned with one another, and different in azimuth or attitude by 45 °. The micro deflector compensator elements 122_1dc, 122_2dc, 122_3dc are respectively a set of upper and lower four-pole lenses 122_1dc-1, 122_1dc-2, a set of upper and lower four-pole lenses 122_2dc-1, 122_2dc-2, and an upper And a set of lower four-pole lenses 122_3 dc-1 and 122_3 dc-2. The upper quadrupole lens 122_1dc-1, 122_2dc-1, 122_3dc-1 is disposed in the upper layer 122-1-1, and the lower quadrupole lens 122_1dc-2, 122_2dc-2, 122_3dc-2 is the lower layer 122-1-2. And are aligned with the upper quadrupole lens 122_1dc-1, 122_2dc-1, 122_3dc-1, respectively. As an example, the azimuth angle of the upper quadrupole lens 122_1dc-1,122_2dc-1,122_3dc-1 with respect to the X axis is 0 ° as shown in FIG. 8B, and the lower quadrupole lens 122_1dc-2,122_2dc-2, The azimuthal angle of 122_3dc-2 is 45 ° as shown in FIG. 8C. In FIG. 8D, similar to FIG. 6D, the upper and lower layers are shielded by the upper electrically conductive plate 122-CL1 and the lower electrically conductive plate 122_CL2, and the upper insulator plate 122-IL1 and the lower insulator plate 122-IL2 It is supported by an intermediate insulator plate 122-IL3 having a number of intermediate orifices. For each micro deflector compensator element, deflection fields of any desired direction and circular lens fields are generated by either or both of the upper and lower quadrupole lenses and quadrupole fields in any direction are upper It can be produced by both a 4-pole lens and a lower 4-pole lens.

  Another embodiment of the new multi-beam device is shown in FIG. 9A. As compared to the embodiment 110A of FIG. 4, the transfer lens 133 has been removed from the primary projection imaging system. FIG. 9B illustrates one mode of operation in which the off-axis beamlets 102_2, 102_3 are deflected parallel to the primary optical axis 200_1 by the micro deflector compensator elements 122_2dc, 122_3dc, respectively, at an oblique angle to the surface 7 to be observed. It is incident. This mode can be used for viewing fields that do not have strict requirements for beamlet incidence or require stereo imaging. The micro deflector compensator elements 122_2dc, 122_3dc can compensate for the large off-axis aberrations of the two off-axis beamlets 102_2, 102_3 by passing the objective lens 131 with a large radial offset. FIG. 9C shows another mode of operation in which the off-axis beamlets 102_2, 102_3 are further deflected by the micro deflector compensator elements 102_2 dc, 102_3 dc respectively towards the primary optical axis 200_1 and accordingly the surface to be observed It is incident at a smaller oblique angle to 7. If the micro deflector compensator elements 122_2dc, 122_3dc respectively deflect the off-axis beamlets 102_2, 102_3 so that they pass through the front focal point of the objective lens 131, the off-axis beamlets 102_2, 102_3 are perpendicular to the surface 7 to be observed It will be incident. It is preferable to maintain a long distance between the front focal point of the objective lens 131 and the micro deflector compensator array 122-1 in order to avoid off-axis beamlets 102_2, 102_3 passing through the beam limiting aperture at large angles of incidence .

  As is well known, the more beamlets that scan the surface 7 to be observed, the more charging there may occur. Thus, certain viewing fields may not require some beamlets. In this case, the beamlets may be directed to be blanked by the beamlet limiting plate. FIG. 10 illustrates such an operating mode of the embodiment 110A of FIG. 4 with the micro deflector compensator element 122_2dc off and the beamlet 102_2 blocked by the beamlet limiting plate 121. The micro deflector compensator element 122_2dc may be required to be switched on to direct the beamlet 102_2 blocked by the beamlet limiting plate 121, which is the detailed structure of the source conversion unit 120-1 Depends on

  Based on the embodiment 110A of FIG. 4, another embodiment 111A of the new multi-beam device is proposed in FIG. 11A, and a single-beam electron detector 141 is added. The apparatus operates in a single beam mode if only one beamlet is required for any reason, such as searching for optimal imaging conditions (incident energy and probe current) for an observation field. In this case, beam separator 160 may deflect the corresponding secondary electron beam to single beam electron detector 141. Here, beamlet 102_1 is used as the beamlet. The secondary electron beam 102_1se generated by the beamlet 102_1 is deflected to be detected by the single beam electron detector 141. By using a single beam electron detector 141, the process of adjusting the secondary projection imaging system 150 with respect to the focusing force variation of the objective lens 131 can be avoided. As mentioned above, the focusing power of the objective lens 131 changes if the incident energy and / or current of the beamlet used is changed. Further, FIG. 11B shows another embodiment 112A of the new multi-beam apparatus, in which an in-lens electron detector 142 having a beamlet passage hole is disposed below the beam separator 160. When the apparatus is operated in single beam mode, secondary electrons having a large emission angle among secondary electron beams related to a beamlet to be used are detected by the in-lens electron detector 142 and secondary electrons having a small emission angle Can be detected by the corresponding detection elements of the electron detection device 140 through the beamlet passage holes. Here, beamlet 102_1 is used as the beamlet. Among the secondary electron beams 102_1se generated by the beamlet 102_1, the secondary electrons 102_1se_2 having a large radiation angle collide with the in-lens electron detector 142, and the secondary electrons 102_1se_1 having a small radiation angle are detected by the electron detection device 140 It is biased to The single beam electron detector 141 and the in-lens electron detector 142 may be used in combination. In this case, secondary electrons 102_1se_2 having a large radiation angle are detected by the in-lens electron detector 142, and secondary electrons 102_1se_1 having a small radiation angle are deflected by the beam separator 160 so as to be detected by the single beam electron detector 141. Can be Although not shown here, the in-lens electron detector 142 can also be located above the beam separator 160. In this case, the in-lens electron detector 142 can detect the outer portion of the secondary electron beam 102_1se when the beam separator is off.

  In summary, the present invention proposes a new multi-beam apparatus for observing a sample with high resolution and high throughput. The new multi-beam apparatus can function as a yield management tool to inspect and / or investigate defects on wafers / masks in the semiconductor manufacturing industry. The multi-beam apparatus forms a new source conversion unit that forms multiple parallel virtual images of a single electron source, a condenser lens that adjusts the current of multiple beamlets, and multiple probe spots on the observed surface of the sample Projection imaging system for projecting a plurality of parallel virtual images, a beam separator for deflecting a plurality of secondary electron beams from the surface out of the path of a plurality of beamlets, and a plurality of electron detection devices And a secondary projection imaging system for focusing the plurality of secondary electron beams to be respectively detected by the detection elements of In this new source conversion unit, the imaging means are upstream of the beamlet limiting means, so that the degradation of the image resolution due to electron scattering is mitigated. The imaging means may be a plurality of micro deflectors for forming a plurality of parallel virtual images or a plurality of micro deflector compensators for forming a plurality of parallel virtual images and compensating for off-axis aberrations of the plurality of probe spots. It has an element.

  Although the invention has been described in connection with its preferred embodiments, it should be understood that other modifications and variations can be made without departing from the spirit and scope of the invention as claimed hereinafter. .

Claims (24)

A multi-beam apparatus for observing the surface of a sample,
An electronic source,
A condenser lens below the electron source;
A source conversion unit below the condenser lens,
A primary projection imaging system below the source conversion unit and comprising an objective lens;
A deflection scanning unit within the primary projection imaging system;
A sample stage below the primary projection imaging system;
A beam separator above the objective lens;
A secondary projection imaging system above the beam separator;
An electronic detection device having a plurality of detection elements,
The source conversion unit comprises an imaging means having a plurality of micro deflectors and a beamlet limiting means having a plurality of beam limiting apertures, the imaging means being above the beamlet limiting means,
The electron source, the condenser lens, the source conversion unit, the primary projection imaging system, the deflection scanning unit, and the beam separator are aligned with the primary optical axis of the apparatus, and the sample stage is such that the surface is the The sample is supported to face an objective lens, the secondary projection imaging system and the electronic detection device are aligned with the secondary optical axis of the device, and the secondary optical axis is not parallel to the primary optical axis Parallel and
The electron source produces a primary electron beam along the primary optical axis, and the plurality of micro-deflectors deflect the primary electron beam to form a plurality of parallel virtual images of the electron source, thereby A virtual multi-source array is converted from the electron source, and a plurality of beamlets comprising the virtual multi-source array each pass through the plurality of beam limiting apertures, whereby the current of each beamlet is one corresponding beam Limited by a limiting aperture, the current of the plurality of beamlets can be changed by adjusting the condenser lens,
The primary projection imaging system images the virtual multi-source array on the surface such that a plurality of probe spots are formed on the surface, and the deflection scanning unit is in an observation area on the surface Deflecting the plurality of beamlets such that each of the plurality of scanning regions is scanned by each of the plurality of probe spots,
A plurality of secondary electron beams are respectively generated from the plurality of scanning regions by the plurality of probe spots and are converged when passing through the objective lens, and the beam separator is configured to receive the plurality of secondary electron beams Deflected to a secondary projection imaging system, the secondary projection imaging system focuses and maintains the plurality of secondary electron beams to be respectively detected by the plurality of detection elements, thereby each detection The elements provide an image signal of one corresponding scan area ,
Wherein there beneath the electron source, it has a main opening which is aligned with said primary optical axis, the multi-beam device further Ru a main aperture plate which serves as a beam limiting aperture for the primary electron beam. The multi-beam apparatus according to claim 1 , wherein the primary projection imaging system comprises a transfer lens above the objective and focusing the plurality of beamlets so as to be perpendicularly incident on the surface. The multi-beam apparatus according to claim 2 , wherein each of the plurality of micro-deflectors has a four-pole structure capable of generating a deflection field in any radial direction. The multi-beam device of claim 3 , further comprising a single beam electron detector above the beam separator and usable in single beam mode. 4. A multi-beam device according to claim 3 , further comprising an in-lens electron detector usable in single beam mode, having a beamlet passing hole aligned with the primary optical axis. 5. The multi-beam device according to claim 4 , further comprising an in-lens electron detector having a beamlet passing hole aligned with the primary optical axis, below the beam separator and usable in the single beam mode. . A multi-beam apparatus for observing the surface of a sample,
An electronic source,
A condenser lens below the electron source;
A source conversion unit below the condenser lens,
A primary projection imaging system below the source conversion unit and comprising an objective lens;
A deflection scanning unit within the primary projection imaging system;
A sample stage below the primary projection imaging system;
A beam separator above the objective lens;
A secondary projection imaging system above the beam separator;
An electronic detection device having a plurality of detection elements,
The source conversion unit comprises an imaging means having a plurality of micro deflector compensator elements, and a beamlet limiting means having a plurality of beam limiting apertures, each micro deflector compensator element comprising one micro deflector. One micro-compensator with one micro-lens and one micro-stig-meter, the imaging means being above the beamlet limiting means,
The electron source, the condenser lens, the source conversion unit, the primary projection imaging system, the deflection scanning unit, and the beam separator are aligned with the primary optical axis of the apparatus, and the sample stage is such that the surface is the The sample is supported to face an objective lens, the secondary projection imaging system and the electronic detection device are aligned with the secondary optical axis of the device, and the secondary optical axis is not parallel to the primary optical axis Parallel and
The electron source produces a primary electron beam along the primary optical axis, and the plurality of micro-deflectors deflect the primary electron beam to form a plurality of parallel virtual images of the electron source, thereby A virtual multi-source array is converted from the electron source, and a plurality of beamlets comprising the virtual multi-source array each pass through the plurality of beam limiting apertures, whereby the current of each beamlet is one corresponding beam Limited by a limiting aperture, the current of the plurality of beamlets can be changed by adjusting the condenser lens,
The primary projection imaging system images the virtual multi-source array onto the surface such that a plurality of probe spots are formed on the surface, the one microlens of the one micro compensator and The one micro stigmator compensates for the curvature of field and astigmatism of one corresponding probe spot respectively, and the deflection scanning unit is configured to scan a plurality of scanning areas in an observation area on the surface. Deflect the plurality of beamlets to cause each to
A plurality of secondary electron beams are respectively generated from the plurality of scanning areas by the plurality of probe spots and are converged as they pass through the objective lens, the beam separator being directed to the secondary projection imaging system Deflecting the plurality of secondary electron beams to be incident, the secondary projection imaging system focusing and maintaining the plurality of secondary electron beams to be respectively detected by the plurality of detection elements; Each detection element thereby provides an image signal of one corresponding scan area ,
Wherein there beneath the electron source, it has a main opening which is aligned with said primary optical axis, the multi-beam device further Ru a main aperture plate which serves as a beam limiting aperture for the primary electron beam. Each of the plurality of micro deflector compensator elements serves as the one micro deflector by generating a desired deflection field, and the one micro by generating a desired quadrupole field and a desired circular lens field. The multi-beam device according to claim 7 , having an 8-pole structure functioning as a compensator. Each of the plurality of micro deflector compensator elements has an upper quadrupole structure in the upper layer and a lower quadrupole structure in the lower layer, the upper layer being above the lower layer, the upper quadrupole structure The multi-beam device of claim 7 , wherein the lower quadrupole structure and the lower quadrupole structure are aligned with one another and differ in azimuth by 45 °. The upper quadrupole structure and the lower quadrupole structure are the one micro deflector by generating the desired deflection field and the one quadrupole electrode and the desired circular lens field. 10. The multi-beam device of claim 9 , functioning as a micro compensator. The multi-beam apparatus according to claim 10 , wherein the primary projection imaging system comprises a transfer lens above the objective and focusing the plurality of beamlets so as to be perpendicularly incident on the surface. The multi-beam apparatus of claim 11 , further comprising a single beam electron detector above the beam separator and usable in single beam mode. The multi-beam device according to claim 11 , further comprising an in-lens electron detector usable in single beam mode, having a beamlet passing hole aligned with the primary optical axis. The multi-beam device according to claim 12 , further comprising an in-lens electron detector having a beamlet passing hole aligned with the primary optical axis, below the beam separator and usable in the single beam mode. . A method of constructing a source conversion unit for forming a virtual multi-source array from an electronic source, comprising:
Providing an imaging means comprising an upper layer having a plurality of upper quadrupole structures and a lower layer having a plurality of lower quadrupole structures;
Providing beamlet limiting means below the imaging means and comprising a plurality of beam limiting apertures.
Each upper quadrupole structure is above and aligned with one corresponding lower quadrupole structure, the two differ in azimuth by 45 °, and form a set of quadrupole structures, whereby the plurality An upper quadruple structure of said plurality and said plurality of lower quadruple electrodes form a set of multiple quadrupolar structures,
The plurality of beam limiting apertures are respectively aligned with the plurality of sets of quadrupolar structures;
One quadrupolar structure set functions as a micro deflector that deflects one beamlet of the electron beam generated by the electron source to form a virtual image of the electron source ,
Providing a main aperture plate below the electron source and having a main aperture aligned with the primary optical axis of the electron source and acting as a beam limiting aperture for the electron beam generated by the electron source Furthermore, the method of Ru equipped. The set of one quadrupolar structure further functions as a micro lens that focuses the one beamlet to a desired degree and / or a microstig meter that adds a desired amount of astigmatism to the one beamlet The method according to claim 15 . The method according to claim 15 or 16 , wherein the source conversion unit comprises a top electrically conductive plate having a plurality of top through holes respectively aligned with the plurality of quadrupolar structure sets. 18. The method of claim 17 , wherein the source conversion unit comprises a lower electrically conductive plate having a plurality of lower through holes respectively aligned with the plurality of quadrupolar structure sets. A method for forming a virtual multi-source array from an electron source, comprising:
Each upper quadruple structure is above and aligned with one corresponding lower quadruple structure, a plurality of upper quadruple structures that differ in azimuth by 45 ° and form sets of quadrupolar structures Deflecting an electron beam from the electron source into a plurality of beamlets to form a plurality of virtual images of the electron source by using an upper layer having a plurality of lower layers having a plurality of lower quadrupole structures. When,
Limiting the plurality of beamlets by using a plurality of apertures ;
Providing a main aperture plate below the electron source and having a main aperture aligned with the primary optical axis of the electron source and acting as a beam limiting aperture for the electron beam generated by the electron source Furthermore, the method of Ru equipped. A charged particle beam device,
A single charged particle source providing a primary beam;
Means for converting the primary beam into a plurality of beamlets, comprising: a plurality of deflectors for deflecting the plurality of beamlets; and a plurality of beam limiting apertures below the plurality of deflectors;
A first projection system for forming a plurality of probe spots on a specimen from the plurality of beamlets;
A deflection scanning unit for scanning the plurality of probe spots on the sample;
Means for separating, from the plurality of beamlets, a plurality of signal electron beams respectively generated by collisions of the plurality of beamlets with the sample;
A detection device for receiving the plurality of signal electron beams;
And a second projection system for forming a plurality of the electronic sensing element a plurality of signal spot the detecting device from said plurality of signal electron beams,
Wherein there beneath the singly charged particle source, the charged particles having a primary opening which is aligned to the primary optical axis of the beam system, the primary beam further comprising Ru charged particles primarily aperture plate which serves as a beam limiting aperture for Beam equipment. 21. The charged particle beam device according to claim 20 , further comprising a condenser lens that adjusts the current of the plurality of probe spots. 22. The charged particle beam device according to claim 21 , wherein the conversion means comprises a plurality of compensators respectively compensating the aberration of the plurality of probe spots. An imaging means comprising an upper layer having a plurality of upper quadrupole structures and a lower layer having a plurality of lower quadrupole structures;
Beamlet limiting means below the imaging means and comprising a plurality of beam limiting apertures;
Each upper quadrupole structure is above and aligned with one corresponding lower quadrupole structure, the two differ in azimuth by 45 °, and form a set of quadrupole structures, whereby the plurality An upper quadruple structure of said plurality and said plurality of lower quadruple electrodes form a set of multiple quadrupolar structures,
The plurality of beam limiting apertures are respectively aligned with the plurality of sets of quadrupolar structures;
One quadrupolar structure set functions as a micro deflector that deflects one beamlet of the electron beam generated by the electron source to form a virtual image of the electron source ,
Wherein there beneath the electron source, has a aligned main opening to the primary optical axis of the electron source, Ru further comprises a main aperture plate which serves as a beam limiting aperture for the electron beam generated by the electron source Source conversion unit. The set of one quadrupolar structure further functions as a micro lens that focuses the one beamlet to a desired degree and / or a microstig meter that adds a desired amount of astigmatism to the one beamlet The source conversion unit according to claim 23 .