JP2018513543A - Multiple charged particle beam equipment - Google Patents

Abstract

A multi-beam apparatus for observing a sample with high resolution and high throughput is proposed. In this apparatus, a source conversion unit converts a single electron source into a virtual multi-source array, and a primary projection imaging system forms the array with a plurality of probe spots on a sample. The condenser lens adjusts the current of the plurality of probe spots. In the source conversion unit, the imaging means is upstream of the beamlet limiting means, thereby producing low scattering electrons. The image forming means not only forms a virtual multi-source array, but also compensates for off-axis aberrations of a plurality of probe spots. [Selection] Figure 3A

Description

This application claims the priority of US Provisional Application No. 62 / 130,819 entitled "Multiple Charged Particle Beam Apparatus" filed on Mar. 10, 2015, entitled Ren et al. The entirety of which is hereby incorporated by reference.

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

  During 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. Patterns with increasingly smaller critical feature dimensions are employed to meet the ever-evolving performance requirements of IC chips. Therefore, conventional yield management tools using optical beams are gradually becoming ineligible due to diffraction effects, and more and more yield management tools using electron beams are used. Compared to a photon beam, an electron beam has a shorter wavelength and can provide superior spatial resolution. Currently, yield management tools that use electron beams use the principle of a scanning electron microscope (SEM) that uses a single electron beam, so they can provide high resolution but not high throughput suitable for mass production. Although it is possible to use increasingly higher beam currents to increase throughput, superior spatial resolution is essentially degraded by the Coulomb effect.

  To alleviate throughput constraints, a promising solution that does not use a single electron beam with a large current is to use multiple electron beams, each with a small current. A plurality of electron beams form a plurality of probe spots on one inspection or observation surface of the sample. On the sample surface, a plurality of probe spots can simultaneously scan a plurality of small scanning regions in a large observation area on the sample surface. Secondary electrons are generated from the location where the electrons of each probe spot are incident on the sample surface. Secondary electrons include low-speed secondary electrons (energy of 50 eV or less) and back-scattered 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 observation area that includes all small scan areas can be acquired much faster than scanning that large observation area with a single beam.

  Multiple electron beams are obtained from multiple electron sources, respectively, or from a single electron source. In the former, a plurality of electron beams are usually converged and scanned by a plurality of columns to a plurality of small scanning regions, respectively, and secondary electrons from each scanning region are detected by a single electron detector inside the corresponding column. The Therefore, this apparatus is generally called a multi-column apparatus. Multiple columns can be independent or share a multi-axis magnetic or electromagnetic compound objective (eg, US 8,294,095). The beam spacing between two adjacent beams on the sample surface is usually on the order of 30-50 mm.

  In the latter, a source conversion unit is used to virtually change a single electron source into multiple sub-sources. The source conversion unit includes one beamlet forming unit and one image forming unit. The beamlet forming means basically comprises a plurality of beam limiting apertures that respectively split the primary electron beam generated by a single electron source into a plurality of sub-beams or beamlets. The image forming means basically includes a plurality of electron optical elements that respectively converge or deflect the 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 that emits one corresponding beamlet. More beamlets are available because the beamlet spacing or beam limiting aperture spacing is at the micrometer level, so the source conversion unit can be manufactured by a semiconductor manufacturing process or a MEMS (microelectromechanical system) process. . Naturally, one primary projection imaging system and one deflection scanning unit in one single column can be 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. Therefore, this apparatus is generally called a multi-beam apparatus.

  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). A 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, and a plurality of beamlets (2_1 to 2_3) are divided. Each of the lenses converges a plurality of beamlets so as 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 can be virtual images under certain conditions where each of the multiple lenses is an aperture lens. US 7,244,949 and US 7,880,143 propose multi-beam devices having one image forming means of this type. In the source conversion unit 20-2 in FIG. 1B, the image forming unit 22-2 includes 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 simply used. A plurality of beamlets are respectively deflected so as to form a plurality of parallel virtual images (2_2v and 2_3v) of one electron source.

  The idea of using a deflector to form a virtual image of an electron source was used in the famous double slit electron interference experiment as early as the 1950s. Here, as shown in Fig. 2 (Fig. 1 of "Double slit electron interference experiment of Merli Missiloli Poggi", published in Physics in Perspective, 14 (2012), 178-195, by Rodolfo Rosa) An electron biprism is used to form two virtual images. An electron biprism basically comprises two parallel plates at ground potential and a very thin wire F between them. When a potential not equal to the ground potential is applied to the wire F, the electron biprism becomes two deflectors having deflections in opposite directions. The primary electron beam from the electron source S passes through these two deflectors, resulting in two deflected beamlets that form virtual images S1 and S2 of the electron source S. When the potential is positive, the two beamlets overlap each other, and interference fringes appear in the overlapping region.

  Since then, the above idea has been used in many ways in multi-beam devices. JP-A-10-339711 and US 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 document) to form more than two probe spots on the sample surface. Thus, high throughput can be provided. The annular deflector includes an inner annular electrode and an outer annular electrode. If the electric potentials of the two annular electrodes are not equal to each other, one electric field appears in the annular gap in the local radial direction, so the annular deflector deflects more than two beamlets together in various directions. be able to. Furthermore, the deflecting function of the annular deflector can also be performed by one corresponding deflector array having a plurality of multipolar deflectors arranged along an 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 various incident angles, thereby causing electrons of various intensities. I suffer from scattering. Scattered electrons in each beamlet expand 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 is changed. The beamlet forming means has a plurality of groups of openings, and it is necessary to make the size of the opening of one group different from the other groups. Changing a group at the time of use is very time consuming. In addition, the secondary electron beam can only be focused on a large number of detector elements of the in-lens detector in some specific operating conditions of the objective lens. This limits the application fields that can be used.

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

  It is an object of the present invention to provide both high resolution and high throughput for observing a sample, and in particular functions as a yield management tool for inspecting and / or investigating defects on a wafer / mask in the semiconductor manufacturing industry. It is an object of the present invention to provide a novel multi-beam apparatus. The multi-beam device first forms a plurality of parallel virtual images of a single electron source, and then creates a new source conversion unit that limits the current of the corresponding plurality of beamlets and the current of the plurality of beamlets. A condenser lens to be adjusted, a primary projection imaging system that projects a plurality of parallel virtual images so as to form a plurality of probe spots on the surface to be observed of the sample, and a plurality of secondary electron beams from the surface A beam separator that deflects away from the let path and a secondary projection imaging system that converges a plurality of secondary electron beams so as to be respectively detected by a plurality of detection elements of the electron detection device are employed.

  Accordingly, the present invention provides a source conversion unit, which comprises an image forming means comprising an upper layer having a plurality of upper quadrupole structures and a lower layer having a plurality of lower quadrupole structures, and below the image forming means. And a beamlet limiting means including a plurality of beam limiting apertures. Each upper quadrupole structure is above and aligned with one corresponding lower quadrupole structure, both differing in azimuth by 45 ° and forming a quadrupole structure set. Accordingly, the plurality of upper quadrupole structures and the plurality of lower quadrupole structures form a set of a plurality of quadrupole structures. The plurality of beam limiting apertures are each aligned with a plurality of sets of quadrupole structures. A micro deflector that deflects one beamlet of an electron beam generated by an electron source to form a virtual image of the electron source, a micro lens that converges one beamlet to a desired degree, And / or functions as a microstigmator that adds a desired amount of astigmatism to one beamlet.

  The present 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 a 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, and above the objective lens A beam separator, a secondary projection imaging system above the beam separator, and an electron detection device having a plurality of detection elements. The source conversion unit includes an image forming unit having a plurality of micro deflectors and a beamlet limiting unit having a plurality of beam limiting apertures, the image forming unit being above the beamlet limiting unit. The electron source, condenser lens, source conversion unit, primary projection imaging system, deflection scanning unit, and beam separator are aligned with the primary optical axis of the device. The sample stage supports the sample so 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 generates a primary electron beam along the primary optical axis, and the plurality of microdeflectors deflect the primary electron beam to form a plurality of parallel virtual images of the electron source. Thereby, the virtual multi-source array is converted from the electron source, and a plurality of beamlets including the virtual multi-source array pass through the plurality of beam limiting apertures, respectively. Thereby, the current of each beamlet is limited by one corresponding beam limiting aperture, and the current of multiple beamlets can be changed by adjusting the condenser lens. The primary projection imaging system images a virtual multi-source array on a surface, thereby forming a plurality of probe spots on the surface. The deflection scanning unit deflects the plurality of beamlets so that the plurality of scanning areas in the observation area on the surface are scanned by the plurality of probe spots, respectively. A plurality of secondary electron beams are respectively generated from a plurality of scanning regions by a plurality of probe spots and converged when passing through the objective lens. The beam separator deflects a plurality of secondary electron beams into the secondary projection imaging system, and the secondary projection imaging system focuses the plurality of secondary electron beams so that they are detected by a plurality of detection elements, respectively. And maintain. Thereby, each detection element provides an image signal of one corresponding scanning area.

  The multi-beam apparatus may further comprise a main aperture plate below the electron source, having a main aperture aligned with the primary optical axis and functioning as a beam limiting aperture for the primary electron beam. The primary projection imaging system may include a transfer lens that is above the objective lens and converges the plurality of beamlets to be incident perpendicular to the surface. Each of the plurality of micro deflectors has a quadrupole structure capable of generating a deflection field in an arbitrary radial direction. The multi-beam device may further comprise a single beam electron detector above the beam separator and usable in single beam mode. The multi-beam apparatus may further comprise an in-lens electron detector having a beamlet passage hole aligned with the primary optical axis, below the beam separator and usable in a single beam mode.

  The present 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 a 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, and above the objective lens A beam separator, a secondary projection imaging system above the beam separator, and an electron detection device having a plurality of detection elements. The source conversion unit comprises imaging means having a plurality of microdeflector compensator elements and beamlet restricting means having a plurality of beam limiting apertures, each microdeflector compensator element having one microdeflector and one A microlens and a microcompensator having a microstigmator. The image forming means is above the beamlet limiting means. The electron source, condenser lens, source conversion unit, primary projection imaging system, deflection scanning unit, and beam separator are aligned with the primary optical axis of the device. The sample stage supports the sample so 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 generates a primary electron beam along the primary optical axis, and the plurality of microdeflectors deflect the primary electron beam to form a plurality of parallel virtual images of the electron source. A virtual multi-source array is thereby converted from an electronic source. A plurality of beamlets including a virtual multi-source array each pass through a 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. The primary projection imaging system images a virtual multi-source array on a surface, thereby forming a plurality of probe spots on the surface. One microlens and one microstigmator of one microcompensator compensate for the field curvature and astigmatism of one corresponding probe spot, respectively. A plurality of beamlets are deflected so that the scanning region is scanned by a plurality of probe spots, respectively. A plurality of secondary electron beams are respectively generated from a plurality of scanning regions by a plurality of probe spots and converged when passing through the objective lens, and a plurality of beam separators are incident on the secondary projection imaging system. The secondary electron beam is deflected. A secondary projection imaging system converges and maintains a plurality of secondary electron beams to be detected by a plurality of detection elements, respectively, whereby each detection element provides an image signal of one corresponding scanning region. .

  The multi-beam apparatus may further comprise a main aperture plate below the electron source, having a main aperture aligned with the primary optical axis and functioning as a beam limiting aperture for the primary electron beam. Each of the plurality of micro-deflector compensator elements as a single micro-deflector by generating a desired deflection field and a single micro-compensator by generating a desired quadrupole field and a desired circular lens field. It may have a functioning octupole 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 structure. The structures are aligned with each other and differ in azimuth by 45 °. The upper quadrupole structure and the lower quadrupole structure are used 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. May function. The primary projection imaging system may include a transfer lens that is above the objective lens and converges the plurality of beamlets to be incident perpendicular to the surface. The multi-beam device may further comprise a single beam electron detector above the beam separator and usable in single beam mode. The multi-beam apparatus may further comprise an in-lens electron detector having a beamlet passage hole aligned with the primary optical axis, below the beam separator and usable in a single beam mode.

  The present invention also provides a method of constructing a source conversion unit for forming a virtual multi-source array from an electronic source, comprising an upper layer having a plurality of upper quadrupole structures and a plurality of lower quadrupole structures. And a step of providing a beamlet restricting means provided with a plurality of beam restricting apertures below the image forming means. Each upper quadrupole structure is above and aligned with one corresponding lower quadrupole structure, both differing in azimuth by 45 ° and forming a quadrupole structure set. Thereby, a plurality of upper quadrupole structures and a plurality of lower quadrupole structures form a set of a plurality of quadrupole structures. The plurality of beam limiting apertures are each aligned with a plurality of sets of quadrupole structures. A micro deflector that deflects one beamlet of an electron beam generated by an electron source so as to form a virtual image of the electron source, and a micro that converges the one beamlet to a desired degree. It functions as a lens and / or a microstigmator 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 each aligned with a plurality of sets of quadrupole structures. The source conversion unit may further include a lower conductive plate having a plurality of lower through holes each aligned with a plurality of sets of quadrupole structures.

  The present invention also provides a method for forming a virtual multi-source array from an electron source, which uses an upper layer having a plurality of upper quadrupole structures and a lower layer having a plurality of lower quadrupole structures. Thereby deflecting the electron beam from the electron source into a plurality of beamlets and constraining 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 differing in azimuth by 45 ° and forming a quadrupole structure set.

  The present invention also provides a charged particle beam device comprising 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, 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 on a plurality of electron detection elements of the detection device, respectively. The conversion means includes a plurality of deflectors for deflecting the 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 with the specimen.

  The charged particle beam apparatus may further include a condenser lens that adjusts currents of a plurality of probe spots. The conversion means includes a plurality of compensators that compensate the aberrations of the plurality of probe spots.

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

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

It is the schematic of the conventional source conversion unit. It is the schematic of the conventional source conversion unit.

It is the schematic of the electron interference experiment using an electron beam biprism.

It is the schematic of one structure of the new multi-beam apparatus which concerns on one embodiment of this invention.

FIG. 3B is a schematic diagram of an operation mode of the new multi-beam apparatus of FIG. 3A. FIG. 3B is a schematic diagram of an operation mode of the new multi-beam apparatus of FIG. 3A. FIG. 3B is a schematic diagram of an operation mode of the new multi-beam apparatus of FIG. 3A.

It is the schematic of the other structure of the new multi-beam apparatus which concerns on other embodiment of this invention.

FIG. 3B is a schematic diagram of the configuration of the image forming unit of FIG. 3A according to another embodiment of the present invention. FIG. 3B is a schematic diagram of the configuration of the image forming unit of FIG. 3A according to another embodiment of the present invention. FIG. 3B is a schematic diagram of the configuration of the image forming unit of FIG. 3A according to another embodiment of the present invention.

FIG. 3B is a schematic diagram of the configuration of the image forming unit of FIG. 3A according to another embodiment of the present invention. FIG. 3B is a schematic diagram of the configuration of the image forming unit of FIG. 3A according to another embodiment of the present invention. FIG. 3B is a schematic diagram of the configuration of the image forming unit of FIG. 3A according to another embodiment of the present invention. FIG. 3B is a schematic diagram of the configuration of the image forming unit of FIG. 3A according to another embodiment of the present invention.

FIG. 5 is a schematic diagram of the configuration of the advanced image forming means of FIG. 4 according to another embodiment of the present invention.

FIG. 5 is a schematic diagram of the configuration of the advanced image forming means of FIG. 4 according to another embodiment of the present invention. FIG. 5 is a schematic diagram of the configuration of the advanced image forming means of FIG. 4 according to another embodiment of the present invention. FIG. 5 is a schematic diagram of the configuration of the advanced image forming means of FIG. 4 according to another embodiment of the present invention. FIG. 5 is a schematic diagram of the configuration of the advanced image forming means of FIG. 4 according to another embodiment of the present invention.

It is the schematic of the other structure of the new multi-beam apparatus which concerns on other embodiment of this invention.

FIG. 9B is a schematic diagram of an operation mode of the new multi-beam apparatus of FIG. 9A. FIG. 9B is a schematic diagram of an operation mode of the new multi-beam apparatus of FIG. 9A.

FIG. 5 is a schematic diagram of one operation mode of the new multi-beam apparatus of FIG. 4.

It is the schematic of the other structure of the new multi-beam apparatus which concerns on other embodiment of this invention, and its one operation mode.

It is the schematic of the other structure of the new multi-beam apparatus which concerns on other embodiment of this invention, and its one operation mode.

  Various exemplary embodiments of the invention will now be described more fully with reference to the accompanying drawings, which illustrate several exemplary embodiments of the invention. Without limiting the scope of protection of the present invention, all of the description of the embodiments and drawings refer to an electron beam as an example, but these embodiments are used to limit the present invention to specific charged particles. 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 the differences with respect 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 the exemplary embodiments of the invention are susceptible to various modifications and alternative forms, the embodiments are shown by way of example in the drawings and will herein be described in detail. However, there is no intention to limit the exemplary embodiments of the invention to the specific forms disclosed, in contrast, the exemplary embodiments of the invention are intended to cover any variations that fall within the scope of the invention. , Equivalents, and alternatives.

  In the present invention, the “axial direction” means “the optical axis direction of a lens (circular or multipolar), imaging system, or apparatus”, and “radial direction” means “the direction perpendicular to the optical axis”. “On-axis” means “on or aligned with the optical axis”, and “off-axis” means “not on the optical axis or aligned with the optical axis” Not. "

  In the present invention, “the imaging system is aligned with the optical axis” means “all the electro-optical elements (circular lenses, multipole lenses, etc.) are aligned with the optical axis”.

  In the present invention, the X axis, the Y axis, and the Z axis 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 a surface to be observed or inspected of a sample”, and “secondary electrons” means “primary electrons from the surface”. "Electrons generated by".

  In the present invention, “signal electrons” refers to “electrons generated by a primary charged particle beam from the surface of a sample to be observed or inspected”.

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

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

  Subsequently, the present invention provides several embodiments of the new multi-beam apparatus. A multi-beam device is a multi-beam device that 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 a plurality of beamlets. A condenser lens that adjusts the current of the first projection, a primary projection imaging system that projects a plurality of parallel virtual images so as to form a plurality of probe spots on the surface to be observed of the sample, and a plurality of secondary electron beams from the surface A beam separator that deflects the plurality of beamlets away from the path of the plurality of beamlets, and a secondary projection imaging system that converges the plurality of secondary electron beams so as to be respectively detected by the plurality of detection elements of the electron detection device, adopt.

  The new source conversion unit comprises image forming means having a plurality of micro deflectors and beamlet limiting means having a plurality of beam limiting apertures, the image forming means being upstream of the beamlet limiting means. A primary electron beam from a single electron source is first deflected by a plurality of microdeflectors to form a plurality of parallel virtual images of the single electron source, and the plurality of beams forming a plurality of parallel virtual images A let passes vertically or substantially vertically through a plurality of beam restrictions. In this way, the multiple beam limiting apertures not only generate less scattered electrons than the prior art, but also block the scattered electrons generated upstream, thus degrading image resolution due to electron scattering. Disappears. The image forming means further includes a plurality of micro-compensators that respectively compensate off-axis aberrations (field curvature and astigmatism) of the plurality of probe spots, thereby further improving the image resolution of the surface to be observed.

  FIG. 3A shows an embodiment 100A of a new multi-beam apparatus. 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 arranged along the primary optical axis 100_1 and the primary optical axis. 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 just above the new source conversion unit 120 as shown. The new source conversion unit 120 includes a micro deflector array 122 having two micro deflectors 122_2 and 122_3, and a beamlet limiting plate 121 having three beam limiting apertures 121_1, 121_2, and 121-3. 121_1 is 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 includes a transfer lens 133 and an objective lens 131. The deflection scanning unit 132 includes at least one deflector. The beam separator 160 is one Wien filter. The secondary projection imaging system 150 includes a reverse scanning deflector 151, a zoom lens 152 (including at least two lenses 152_1 and 152_2), and a reverse rotating magnetic lens 154. The electronic detection device 140 includes three detection elements 140_1, 140_2, and 140_3. Each of the above-described lenses may be an electrostatic lens, a magnetic lens, or an electromagnetic compound lens.

  3B-3D show the three operating modes of the new multi-beam apparatus 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 generate high energy (for example, 8 to 20 keV), high angular intensity (for example, 0.5 to 5 mA / sr). ) And (imaginary or real) crossover 101s (illustrated by an on-axis ellipse symbol) is drawn and / or accelerated so that the primary electron beam 102 is crossed It is convenient to consider that the single electron source 101, emitted from the over 101s, is simplified to be the crossover 101s.

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

  Subsequently, the crossover 101s and the two parallel off-axis virtual images 102_2v and 102_3v are imaged on the surface 7 to be observed by the transfer lens 133 and the objective lens 131, and these images are formed there on three probe spots 102_1s. , 102_2s, 102_3s. In order to cause the two off-axis beamlets 102_2 and 102_3 to enter the observed surface 7 perpendicularly, the transfer lens 133 converges them so as to pass the front focal point of the objective lens 131. When the objective lens 131 includes one magnetic lens, the two off-axis beamlets 102_2 and 102_3 do not have to pass through the front focal point accurately due to the influence of 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.

  The secondary electron beams 102_1se, 102_2se, and 102_3se emitted from the three scanning regions are converged 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. To be biased. The lenses 152 and 153 converge the secondary electron beam onto the three detection elements 140_1 to 140_3, respectively. Thereby, each detection element provides an image signal of one corresponding scanning area. When some secondary electrons of a secondary electron beam from one scanning area are directed to an adjacent detection element, the image signal of the adjacent detection element includes irrelevant information from the scanning area and The information irrelevant to the detecting element is the crosstalk from the scanning region. In order to avoid crosstalk between the detection elements, the zoom lens 152 makes the spot size of each secondary electron beam smaller than the corresponding detection element, and the reverse scanning deflector 151 includes the beamlets 102_1 to 102_3 by the deflection scanning unit 132. The secondary electron beams 102_1se to 102_3se are deflected synchronously so as to be maintained in the corresponding detection element during the deflection.

  Various samples usually require various observation conditions such as beamlet incident energy and current. This is particularly true in the inspection and / or investigation of wafer / mask defects in the semiconductor manufacturing industry. The convergence force of the objective lens 131 changes depending on the incident energy, which affects the position of the secondary electron beam on the electron detection device 140 and causes crosstalk. In this case, the zoom lens 152 is adjusted so as to remove the radial displacement of the secondary electron beam. When the objective lens 131 includes one magnetic lens, the reverse rotation magnetic lens 154 is adjusted so as to remove the rotation of the secondary electron beam.

  Each of the two off-axis probe spots 102_2s, 102_3s comprises off-axis aberrations generated by the objective lens 131, the transfer lens 133, and the condenser lens when turned on. Off-axis aberrations at each off-axis probe spot can be reduced by optimizing the trajectory of the corresponding beamlet individually. The static part of off-axis aberrations can be reduced by adjusting the deflection force of the corresponding micro deflector. The dynamic part of off-axis aberrations can be reduced by optimizing the performance of the deflection scanning unit 132. Therefore, the deflection scanning unit 132 may include a plurality of deflectors.

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

  As with a conventional SEM, the size of each probe spot is minimized by balancing geometrical aberrations, diffraction aberrations, Gaussian image size, and Coulomb effect. The converging function of the condenser lens 110 changes the imaging magnification from the crossover 101s to the surface 7 to be observed, and this affects the balance. Therefore, the size of each probe spot can be increased. In order to prevent the probe spot size from greatly expanding when the beamlet current is greatly changed, a considerable change may be made to the size of the beam limiting apertures 121_1 to 121_3. As a result, the beamlet limiting plate 121 preferably has multiple groups of beam limiting apertures. The size of the beam limiting aperture in one group is different from that in other groups. Alternatively, the convergence force of the transfer lens 133 may be changed so as to reduce the fluctuation of the imaging magnification. Since the trajectories of the off-axis beamlets 102_2 and 102_3 are influenced by fluctuations in the convergence force of the transfer lens 133, considerable adjustment may be made to the deflecting force so that the deflecting forces of the micro deflectors 122_2 and 122_3 maintain the trajectory. . In this way, the beamlets 102_2 and 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 apparatus. Unlike Embodiment 100A, the new source conversion unit 120-1 includes a micro-deflector compensator array 122-1 having three micro-deflector compensator elements 122_1dc, 122_2dc, and 122_3dc. Each micro deflector compensator element includes one micro deflector and one micro compensator having one micro lens and one micro stigmator. The micro deflector is used to form one virtual multi-source array, similar to the function of the micro deflectors 122_2, 122_3 shown in FIGS. As is well known, the condenser lens 110, the transfer lens 133, and the objective lens 131 generate off-axis aberrations. As described above, the effect of off-axis aberrations on the size of the probe spot can be reduced by individually optimizing the beamlet trajectory. Therefore, the microlens and the microstigmator are used so as to compensate the field curvature 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 and 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, and thereby deflects the beamlet 102_2 in the X axis direction. FIG. 5B shows one embodiment of a micro-deflector array 122 that deflects eight beamlets. Since each micro deflector has a spatial orientation, it is difficult to make one micro deflector array 122 with a large number of micro deflectors. From a manufacturing point of view, it is desirable that all micro-deflectors have the same geometric configuration and attitude. Hence, a micro deflector having a quadrupole or quadrupole configuration can meet this requirement, as shown in FIG. 5C. Four deflectors 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, the drive circuit needs to be connected to each electrode. In order to prevent the drive circuit from being damaged by the primary electron beam 102, it is preferable to place a single electrically conductive plate above the electrodes of all the microdeflectors of FIGS. As an example, FIG. 6 shows that an upper conductive plate 122-CL1 having many upper through holes and an upper insulator plate 122-IL1 having many upper orifices are electrodes of the micro deflectors 122_1 to 122_3. It is arranged above. 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 less than or equal to the inner diameter of the corresponding micro deflector electrode to protect the drive circuit, and the radial size of each upper orifice avoids charging of the inner sidewalls Therefore, it is larger than the radial size of the corresponding upper through hole. In this way, the deflection field of all the microdeflectors is reduced because the range of the edge is shortened on the upper side thereof.

  Based on FIG. 6A, the micro-deflector array 122 of FIG. 6B further comprises a lower electrically conductive plate 122-CL2 having a number 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, the deflection field of all micro-deflectors is reduced because the range of the edge is shortened on both the upper and lower sides, thereby reducing deflection aberrations. 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 of the corresponding micro-deflector electrode. The micro deflector array 122 of FIG. 6D is a combination of FIG. 6B and FIG. 6C, and has a more stable configuration.

  FIG. 7 shows one embodiment of the micro-deflector compensator element 122_2dc of the micro-deflector compensator array 122-1 of FIG. 4, which has an 8-pole configuration. The eight electrodes 122_2dc_e1 to 122_2dc_e8 include a dipole field (deflection field) having a basic amount for generating a virtual image of the electron source 1 in an arbitrary direction and an additional amount for correcting distortion, and four electrodes for correcting astigmatism in an arbitrary direction. It can be driven to generate a multipole field (astigmatism field) and a circular lens field that corrects field curvature.

  FIG. 8A shows another embodiment of the micro-deflector compensator array 122-1 of FIG. Each microdeflector compensator element comprises a set of quadrupole lenses arranged in two layers, aligned with each other and differing in azimuth or orientation by 45 °. The micro-deflector compensator elements 122_1dc, 122_2dc, 122_3dc are respectively a set of upper and lower quadrupole lenses 122_1dc-1, 122_1dc-2, a set of upper and lower quadrupole lenses 122_2dc-1, 122_2dc-2, and an upper part. And a pair of lower quadrupole lenses 122_3dc-1 and 122_3dc-2. The upper quadrupole lenses 122_1dc-1, 122_2dc-1, 122_3dc-1 are disposed on the upper layer 122-1-1, and the lower quadrupole lenses 122_1dc-2, 122_2dc-2, 122_3dc-2 are disposed on the lower layer 122-1-2. And aligned with the upper quadrupole lenses 122_1dc-1, 122_2dc-1, 122_3dc-1. As an example, with respect to the X axis, the azimuth angles of the upper quadrupole lenses 122_1dc-1, 122_2dc-1, 122_3dc-1 are 0 ° as shown in FIG. 8B, and the lower quadrupole lenses 122_1dc-2, 122_2dc-2, The azimuth angle of 122_3dc-2 is 45 ° as shown in FIG. 8C. In FIG. 8D, as in FIG. 6D, the upper layer and the lower layer are shielded by the upper conductive plate 122-CL1 and the lower 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 microdeflector compensator element, a deflection field and a circular lens field in any desired direction are generated by one or both of an upper quadrupole lens and a lower quadrupole lens, and a quadrupole field in any direction is upper. It can be generated by both a quadrupole lens and a lower quadrupole lens.

  FIG. 9A shows another embodiment of the new multi-beam apparatus. Compared to the embodiment 110A of FIG. 4, the transfer lens 133 has been removed from the primary projection imaging system. FIG. 9B shows one mode of operation where off-axis beamlets 102_2 and 102_3 are deflected by the micro deflector compensator elements 122_2dc and 122_3dc, respectively, parallel to the primary optical axis 200_1 and at an oblique angle to the surface 7 to be observed. Incident. This mode can be used for observational fields that do not have strict requirements on beamlet incidence or that require stereo imaging. The micro-deflector compensator elements 122_2dc and 122_3dc can compensate for large off-axis aberrations of the two off-axis beamlets 102_2 and 102_3 due to passing through the objective lens 131 with large radial misalignment. FIG. 9C shows another mode of operation where the off-axis beamlets 102_2 and 102_3 are further deflected by the micro-deflector compensator elements 102_2dc and 102_3dc, respectively, toward the primary optical axis 200_1, and accordingly the surface to be observed 7 is incident at a smaller oblique angle. When the off-axis beamlets 102_2 and 102_3 are deflected so that the micro deflector compensator elements 122_2dc and 122_3dc pass through the front focal point of the objective lens 131, the off-axis beamlets 102_2 and 102_3 are perpendicular to the surface 7 to be observed. Incident. In order to avoid the off-axis beamlets 102_2 and 102_3 passing through the beam limiting aperture at a large incident angle, 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. .

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

  Based on the embodiment 110A of FIG. 4, in FIG. 11A, another embodiment 111A of a new multi-beam device has been proposed and a single beam electron detector 141 has been added. If only one beamlet is needed for some reason, such as searching for the best imaging conditions (incident energy and probe current) for a field of observation, the device will operate in single beam mode. In this case, the beam separator 160 can deflect the corresponding secondary electron beam to the single beam electron detector 141. Here, the beamlet 102_1 is used as the beamlet. The secondary electron beam 102_1se generated by the beamlet 102_1 is deflected so as to be detected by the single beam electron detector 141. By using the single beam electron detector 141, the process of adjusting the secondary projection imaging system 150 with respect to the convergence force variation of the objective lens 131 can be avoided. As described above, the convergence force of the objective lens 131 changes as the incident energy and / or current of the beamlet used changes. 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 the single beam mode, the secondary electrons having a large emission angle among the secondary electron beams related to the beamlets used are detected by the in-lens electron detector 142 and the secondary electrons having a small emission angle are detected. Can be detected by a corresponding detection element of the electron detection device 140 through the beamlet passage hole. Here, the beamlet 102_1 is used as the beamlet. Of the secondary electron beam 102_1se generated by the beamlet 102_1, the secondary electron 102_1se_2 having a large emission angle collides with the in-lens electron detector 142, and the secondary electron 102_1se_1 having a small emission angle is detected by the electron detection device 140. Is deflected to A single beam electron detector 141 and an in-lens electron detector 142 may be used in combination. In this case, the secondary electrons 102_1se_2 having a large radiation angle are detected by the in-lens electron detector 142, and the 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. Although not shown here, the in-lens electron detector 142 may be disposed 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. This new multi-beam apparatus can serve as a yield management tool for inspecting and / or investigating defects on wafers / masks in the semiconductor manufacturing industry. The multi-beam device 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 surface to be observed of the sample. A primary projection imaging system that projects a plurality of parallel virtual images, a beam separator that deflects 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 that converges a plurality of secondary electron beams so as to be detected by the respective detection elements. In this new source conversion unit, the image forming means is upstream of the beamlet limiting means, so that the degradation of image resolution due to electron scattering is mitigated. The image forming means includes 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 a plurality of probe spots. With elements.

  While the invention has been described in connection with preferred embodiments thereof, it is to be understood that other modifications and variations can be made without departing from the spirit and scope of the invention as claimed below. .

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 includes an image forming unit having a plurality of micro deflectors, and a beamlet limiting unit having a plurality of beam limiting apertures, the image forming unit being above the beamlet limiting unit,
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 a primary optical axis of the apparatus, and the sample stage has the surface having the surface The sample is supported so as to face the objective lens, the secondary projection imaging system and the electron detection device are aligned with a secondary optical axis of the apparatus, and the secondary optical axis is not aligned with the primary optical axis. Parallel,
The electron source generates a primary electron beam along the primary optical axis, and the plurality of microdeflectors 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 including 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, whereby 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 so that the plurality of scanning spots respectively scan 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 converged when passing through the objective lens, and the beam separator causes the plurality of secondary electron beams to pass through the plurality of secondary electron beams. Deflecting to a secondary projection imaging system, wherein the secondary projection imaging system converges and maintains the plurality of secondary electron beams to be detected by the plurality of detection elements, respectively, thereby detecting each A multi-beam device in which an element provides an image signal of a corresponding scanning area.   The multi-beam apparatus according to claim 1, further comprising a main aperture plate below the electron source, having a main aperture aligned with the primary optical axis, and functioning as a beam limiting aperture for the primary electron beam.   The multi-beam apparatus according to claim 2, wherein the primary projection imaging system includes a transfer lens that is above the objective lens and converges the plurality of beamlets so as to be perpendicularly incident on the surface.   4. The multi-beam apparatus according to claim 3, wherein each of the plurality of micro deflectors has a quadrupole structure capable of generating a deflection field in an arbitrary radial direction.   The multi-beam apparatus of claim 4 further comprising a single beam electron detector above the beam separator and usable in a single beam mode.   The multi-beam apparatus according to claim 4, further comprising an in-lens electron detector having a beamlet passage hole aligned with the primary optical axis and usable in a single beam mode.   6. The multi-beam apparatus according to claim 5, further comprising an in-lens electron detector having a beamlet passage 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 imaging means having a plurality of microdeflector compensator elements and beamlet restricting means having a plurality of beam limiting apertures, each microdeflector compensator element having one microdeflector, A microcompensator having a microlens and a microstigmator, the image forming 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 a primary optical axis of the apparatus, and the sample stage has the surface having the surface The sample is supported so as to face the objective lens, the secondary projection imaging system and the electron detection device are aligned with a secondary optical axis of the apparatus, and the secondary optical axis is not aligned with the primary optical axis. Parallel,
The electron source generates a primary electron beam along the primary optical axis, and the plurality of microdeflectors 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 including 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, thereby forming a plurality of probe spots on the surface, the one microlens of the one microcompensator and The one microstigmator compensates 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 regions in the observation area on the surface as the plurality of probe spots. Deflecting the plurality of beamlets to scan each of
A plurality of secondary electron beams are respectively generated from the plurality of scanning regions by the plurality of probe spots and converged when passing through the objective lens, and the beam separator is directed to the secondary projection imaging system. Deflecting the plurality of secondary electron beams to be incident, wherein the secondary projection imaging system converges and maintains the plurality of secondary electron beams to be respectively detected by the plurality of detection elements; A multi-beam apparatus whereby each detection element provides an image signal of one corresponding scanning area.   The multi-beam apparatus according to claim 8, further comprising a main aperture plate below the electron source, having a main aperture aligned with the primary optical axis, and functioning 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-deflector element by generating a desired quadrupole field and a desired circular lens field. The multi-beam apparatus according to claim 9, which has an octupole structure that functions 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, and the upper quadrupole structure. The multi-beam device according to claim 9, wherein the lower quadrupole structure is aligned with each other and has an azimuth angle of 45 °.   The upper quadrupole structure and the lower quadrupole structure are formed as the one micro-deflector by generating a desired deflection field, and the one quadrupole field and a desired circular lens field by generating the one quadrupole field. The multi-beam device according to claim 11, which functions as a micro compensator.   The multi-beam apparatus according to claim 12, wherein the primary projection imaging system includes a transfer lens that is above the objective lens and converges the plurality of beamlets so as to be perpendicularly incident on the surface.   The multi-beam apparatus of claim 13, further comprising a single beam electron detector above the beam separator and usable in a single beam mode.   The multi-beam apparatus according to claim 13, further comprising an in-lens electron detector having a beamlet passage hole aligned with the primary optical axis and usable in a single beam mode.   15. The multi-beam device of claim 14, further comprising an in-lens electron detector having a beamlet passage 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 image forming 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 image forming means and comprising a plurality of beam limiting apertures;
Each upper quadrupole structure is above one corresponding lower quadrupole structure and is aligned with the lower quadrupole structure, both differing in azimuth by 45 ° and forming a quadrupole structure set, thereby The upper quadrupole structure and the plurality of lower quadrupole structures form a plurality of quadrupole structures,
The plurality of beam limiting apertures are respectively aligned with the plurality of sets of quadrupole structures;
A set of four-pole structures deflects one beamlet of the electron beam generated by the electron source so as to form a virtual image of the electron source, and converges the one beamlet to a desired degree. A method of functioning as a micro lens and / or a micro stigmator for adding a desired amount of astigmatism to the one beamlet.   The method of claim 17, wherein the source conversion unit comprises an upper conductive plate having a plurality of upper through holes each aligned with the plurality of sets of quadrupole structures.   The method of claim 18, wherein the source conversion unit comprises a lower conductive plate having a plurality of lower through holes each aligned with the plurality of sets of quadrupole structures. A method for forming a virtual multi-source array from an electronic source, comprising:
A plurality of upper quadrupole structures in which each upper quadrupole structure is above one corresponding lower quadrupole structure and is aligned with the lower quadrupole structure, both differing in azimuth by 45 ° and forming a quadrupole structure set Deflecting the electron beam from the electron source into a plurality of beamlets by using a top layer having a plurality of lower quadrupole structures and
Limiting the plurality of beamlets by using a plurality of apertures. 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 that scans the plurality of probe spots on the specimen;
Means for separating a plurality of signal electron beams respectively generated by collision of the plurality of beamlets with the specimen from the plurality of beamlets;
A detection device for receiving the plurality of signal electron beams;
A charged particle beam apparatus comprising: a second projection system that forms a plurality of signal spots from the plurality of signal electron beams on the plurality of electron detection elements of the detection device, respectively.   The charged particle beam apparatus according to claim 21, further comprising a condenser lens that adjusts currents of the plurality of probe spots.   The charged particle beam apparatus according to claim 22, wherein the conversion unit includes a plurality of compensators that respectively compensate aberrations of the plurality of probe spots. An image forming 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 image forming means and comprising a plurality of beam limiting apertures,
Each upper quadrupole structure is above one corresponding lower quadrupole structure and is aligned with the lower quadrupole structure, both differing in azimuth by 45 ° and forming a quadrupole structure set, thereby The upper quadrupole structure and the plurality of lower quadrupole structures form a plurality of quadrupole structures,
The plurality of beam limiting apertures are respectively aligned with the plurality of sets of quadrupole structures;
A micro deflector that deflects one beamlet of an electron beam generated by an electron source so as to form a virtual image of the electron source, and a micro that converges the one beamlet to a desired degree. A source conversion unit that functions as a lens and / or a microstigmator that adds a desired amount of astigmatism to the one beamlet.