Method and apparatus for precharging a sample for charged particle beam inspection - Patents.com

Abstract

To provide a method and a device for pre-charging a sample for charged particle beam inspection.SOLUTION: A device according to an embodiment includes a charged particle radiation source configured to emit a charged particle beam along a primary beam axis of the device, a focusing lens configured to focus the beam about the primary beam axis, an opening, a first multipolar lens, and a second multipolar lens, and the first multipolar lens is located downstream with respect to the focusing lens and located upstream with respect to the second multipolar lens, and the second multipolar lens is located downstream of the first multipolar lens and upstream of the opening.SELECTED DRAWING: Figure 2A

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Patent Application Publication No. 62 / 566,153, filed Sep. 29, 2017, which is incorporated by reference in its entirety.

[0002] This disclosure relates to methods and apparatus for inspecting (eg, viewing, measuring, and imaging) samples such as wafers and masks used in device manufacturing processes, such as the manufacture of integrated circuits (ICs). [Background technology]

[0003] A device manufacturing process may include impinging a desired pattern on a substrate. To generate the desired pattern, a patterning device, alternatively called a mask or a reticle, may be used. This pattern may be transferred onto a target portion (e.g. comprising part of a die or several dies) on the substrate (e.g. a silicon wafer). The transfer of the pattern is typically by imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. A single substrate may comprise a network of adjacent target portions which are successively patterned. A lithographic apparatus may be used for this transfer. One type of lithographic apparatus is a so-called stepper, in which each target portion is illuminated by exposing the entire pattern onto the target portion in one go. Another type of lithographic apparatus is a so-called scanner, in which each target portion is illuminated by synchronously scanning the substrate parallel or anti-parallel in a given direction while scanning the pattern with a radiation beam in this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.

[0004]

[0003] To monitor one or more steps of a device manufacturing process (e.g., exposure, resist processing, etching, developing, baking, etc.), a sample, such as a substrate patterned by the device manufacturing process or a patterning device used in the device manufacturing process, may be inspected, and the inspection may measure one or more parameters of the sample. The one or more parameters may include, for example, edge placement error (EPE), which is the distance between an edge of a pattern on the substrate or patterning device and a corresponding edge of the intended design of the pattern. Inspection may also uncover pattern defects (e.g., poor connection or separation) and uninvited particles.

[0005]

[0004] Inspection of substrates and patterning devices used in device manufacturing processes can help improve yields. Information gained from inspection can be used to identify defects or to adjust the device manufacturing process. Summary of the Invention

[0006]

[0005] Disclosed herein is an apparatus comprising a charged particle radiation source configured to emit a charged particle beam along a primary beam axis of the apparatus, a focusing lens configured to concentrate the beam around the primary beam axis, an aperture, a first multipole lens, and a second multipole lens, wherein the first multipole lens is located downstream relative to the focusing lens and upstream relative to the second multipole lens, and the second multipole lens is located downstream relative to the first multipole lens and upstream relative to the aperture.

[0007]

[0006] According to an embodiment, the apparatus further comprises a scanning deflector configured to scan the beam relative to the sample.

[0008]

[0007] According to an embodiment, the apparatus further comprises an objective lens configured to focus the beam on the sample.

[0009]

[0008] According to an embodiment, the device further comprises a third multipole lens and a fourth multipole lens, the third multipole lens being located downstream relative to the opening and the fourth multipole lens being located downstream relative to the third multipole lens.

[0010]

[0009] According to an embodiment, the first multipole lens and the second multipole lens are electrostatic lenses.

[0011] According to an embodiment, the first multipole lens and the second multipole lens each have at least four poles.

[0012]

[0011] According to an embodiment, the poles each have a cross-sectional shape of a section of a ring.

[0013]

[0012] According to an embodiment, each of the poles is prismatic or cylindrical.

[0014]

[0013] According to an embodiment, each of the poles is separated from its neighbouring pole by a gap or by a dielectric.

[0015]

[0014] According to an embodiment, the poles are configured such that different voltages are applied to the poles.

[0016]

[0015] According to an embodiment, the first multipole lens is configured to stretch the beam in a first direction and compress the beam in a second direction, and the second multipole lens is configured to stretch the beam in the second direction and compress the beam in the first direction.

[0017]

[0016] Disclosed herein is a method that includes setting a charged particle beam to a first configuration suitable for pre-charging a sample, pre-charging an area of ​​the sample using the charged particle beam in the first configuration, setting the charged particle beam to a second configuration suitable for imaging the sample, and imaging the area using the charged particle beam in the second configuration.

[0018]

[0017] According to an embodiment, a charged particle beam is generated in an apparatus comprising a charged particle radiation source configured to emit a charged particle beam along a primary beam axis of the apparatus, a focusing lens configured to concentrate the beam around the primary beam axis, an aperture, a first multipole lens, and a second multipole lens, wherein the first multipole lens is located downstream with respect to the focusing lens and upstream with respect to the second multipole lens, and the second multipole lens is located downstream with respect to the first multipole lens and upstream with respect to the aperture.

[0019]

[0018] According to an embodiment, setting the beam to the first configuration includes energizing the first multipole lens and the second multipole lens.

[0020]

[0019] According to an embodiment, setting the beam to the second configuration includes de-energizing at least one of the first multipole lens and the second multipole lens.

[0021]

[0020] According to an embodiment, the device further comprises a third multipole lens and a fourth multipole lens, the third multipole lens being located downstream relative to the opening and the fourth multipole lens being located downstream relative to the third multipole lens.

[0022]

[0021] According to an embodiment, setting the beam to the first configuration includes energizing the third multipole lens and the fourth multipole lens.

[0023]

[0022] According to an embodiment, setting the beam to the second configuration includes de-energizing at least one of the third multipole lens and the fourth multipole lens.

[0024]

[0023] Disclosed herein is a computer program product including a non-transitory computer-readable medium having instructions recorded thereon, the instructions, when executed by a computer, performing any of the above methods. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 shows a schematic diagram of an apparatus capable of performing charged particle beam inspection. [Figure 2A] FIG. 2A illustrates, in accordance with an embodiment, a schematic diagram of an apparatus capable of performing charged particle beam inspection, in which the charged particle beam may be used for both pre-charging and imaging. [Figure 2B]

[0026] FIG. 2B shows a schematic of the device of FIG. 2A with the two multipole lenses energized. [Diagram 3]

[0027] FIG. 3 shows a schematic cross section of a quadrupole lens as an example of a multipole lens in the device of FIGS. 2A and 2B. [Figure 4]

[0028] FIG. 4 shows schematic examples of cross-sectional shapes of the beam at the aperture (left panel) and at the sample (right panel) in the apparatus of FIG. 2B. [Figure 5A]

[0029] FIG. 5A shows a schematic top view of another quadrupole lens as an example of a multipole lens in the apparatus of FIGS. 2A and 2B. [Figure 5B]

[0030] FIG. 5B shows a schematic cross-sectional view of the quadrupole lens of FIG. 5A. [Figure 6A]

[0031] FIG. 6A illustrates a schematic diagram of charged particle beam inspection in which a charged particle beam is used for both pre-charging and imaging, according to an embodiment. [Figure 6B-6C]

[0032] FIG. 6B shows the paths of the spots without showing the paths of the probe spots in the alternating scan of the spots for precharging and the probe spots for imaging in FIG. 6A.

[0033] FIG. 6C shows the path of the probe spots without showing the path of the spots in the alternating scan of the spots for precharging and the probe spots for imaging in FIG. 6A. [Figure 7A]

[0034] FIG. 7A illustrates a schematic diagram of charged particle beam inspection in which a charged particle beam is used for both pre-charging and imaging, according to an embodiment. [Figure 7B-7C]

[0035] FIG. 7B shows the paths of the spots without showing the paths of the probe spots in the alternating scan of the spots for precharging and the probe spots for imaging in FIG. 7A.

[0036] FIG. 7C shows the path of the probe spots without showing the path of the spots in the alternating scan of the spots for precharging and the probe spots for imaging in FIG. 7A. [Figure 8A]

[0037] FIG. 8A illustrates a schematic diagram of a charged particle beam inspection in which a charged particle beam is used for both pre-charging and imaging, according to an embodiment. [Fig. 8B-8C]

[0038] FIG. 8B shows the paths of the spots without showing the paths of the probe spots in the alternating scan of the spots for precharging and the probe spots for imaging in FIG. 8A.

[0039] FIG. 8C shows the path of the probe spots without showing the path of the spots in the alternating scan of the spots for precharging and the probe spots for imaging in FIG. 8A. [Figure 9]

[0040] FIG. 9 illustrates generally a flow chart of a method for charged particle beam inspection, according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026]

[0041] There are various techniques for inspecting samples (e.g., substrates and patterning devices). One type of inspection technique is optical inspection, where a light beam is directed at the substrate or patterning device and signals representative of the interaction of the light beam with the sample (e.g., scattering, reflection, diffraction) are recorded. Another type of inspection technique is charged particle beam inspection, where a charged particle (e.g., electron) beam is directed at the sample and signals representative of the interaction of the charged particles with the sample (e.g., secondary emission and backscattered emission) are recorded.

[0027]

[0042] 1 shows a schematic diagram of an apparatus 100 capable of performing charged particle beam inspection. The apparatus 100 may include components configured to generate and control a charged particle beam, such as a radiation source 10 capable of generating charged particles in free space, a beam extraction electrode 11, a focusing lens 12, a beam blanking deflector 13, an aperture 14, a scanning deflector 15, and an objective lens 16. The apparatus 100 may include components configured to detect a signal representative of the interaction of the charged particle beam with a sample, such as an E×B charged particle diversion device 17, a signal detector 21, and the like. The apparatus 100 may also include components, such as a processor, configured to process the signals or to control other components.

[0028]

[0043] In an example inspection process, a charged particle beam 18 is directed to a sample 9 (e.g., a wafer or mask) positioned on a stage 30. A signal 20 representative of the interaction of the beam 18 with the sample 9 is guided by an E×B charged particle diversion device 17 to a signal detector 21. A processor may move the stage 30 or cause the beam 18 to scan.

[0029]

[0044] Because the wavelengths of the charged particles used in charged particle beam inspection are shorter than the wavelengths of light used in optical inspection, charged particle beam inspection has the potential for higher resolution than optical inspection. As device manufacturing processes advance, charged particle beam inspection will become more widely used as the dimensions of features on substrates and patterning devices become smaller and smaller.

[0030]

[0045] In charged particle beam inspection, a charge may be applied to a region of a sample before the region is imaged to better reveal certain features (e.g., voltage contrast defects) within the region. The process of applying a charge before imaging is sometimes referred to as precharging. Precharging may reduce the adverse effects on imaging caused by non-uniform charge distribution within the region, or may improve contrast by taking advantage of differences in the interaction of features within the region with the charge.

[0031]

[0046] Precharging can be accomplished by at least two techniques: flooding and prescanning. In the flooding technique, a separate charge emitter (sometimes called a "flood gun") is used to charge an area with a relatively large amount of charge. After the area is filled with charge, a charged particle beam is used to image the area. The sample may move during flooding. Flooding may last for a period of time on the order of minutes. Switching from flooding to imaging may take several seconds. Relatively long flooding times reduce inspection throughput.

[0032]

[0047] In the pre-scan technique, a charged particle beam is used for both pre-charging and imaging. Using the same charged particle beam for both pre-charging and imaging allows for precise control of pre-charging. A charged particle beam in a form suitable for pre-charging may be scanned over an area before the same beam in a different form suitable for imaging is scanned over the area.

[0033]

[0048] Switching between these configurations should be relatively fast. However, rapid switching between these configurations can be difficult when a much higher beam current density is required for precharging (e.g., to reveal thin voids in copper wiring) than for imaging. The current of the beam can be increased by increasing the beam current density through the aperture. Essentially, a higher current density passes more charge through the aperture per unit time, without changing the aperture size. The current density may be increased by increasing the strength of the focusing lens (e.g., focusing lens 12 in FIG. 1) or by adding another electrostatic circular lens in front of the aperture.

[0034]

[0049] The focusing lens may be a magnetic lens. To increase the strength of the magnetic lens, the excitation current of the magnet in the magnetic lens must be changed. Changing the excitation current takes time, and it may be difficult to precisely control the magnitude of the excitation current. In addition, the strength of the magnetic lens as a function of the excitation current has hysteresis.

[0035]

[0050] The focusing lens may be an electrostatic circular lens. To increase the strength of the electrostatic circular lens, the voltage applied to the electrostatic circular lens must be increased. Changing the magnitude of the voltage (e.g., >1000V) may be necessary to switch between the precharging and imaging configurations, but such a change may take time.

[0036]

[0051] 2A shows a schematic diagram of an apparatus 2000 capable of performing charged particle beam inspection, where the charged particle beam can be used for both pre-charging and imaging, according to an embodiment. The apparatus 2000 comprises a charged particle radiation source 2001, a condenser lens 2002, and an aperture 2007. The radiation source 2001 is configured to emit a charged particle beam along a primary beam axis 2010 of the apparatus 2000. The condenser lens 2002 is configured to concentrate the beam around the primary beam axis 2010. By increasing the strength of the condenser lens 2002, the current density of the beam through the aperture 2007 is increased. The apparatus 2000 also comprises a first multipole lens 2003 and a second multipole lens 2004. The first multipole lens 2003 is located downstream with respect to the condenser lens 2002 and upstream with respect to the second multipole lens 2004. The second multipole lens 2004 is located downstream with respect to the first multipole lens 2003 and upstream with respect to the aperture 2007. As used herein, the expression "component A is located upstream with respect to component B" means that in normal operation of the apparatus, the charged particle beam reaches component A before reaching component B. As used herein, the expression "component B is located downstream with respect to component A" means that in normal operation of the apparatus, the charged particle beam reaches component B after reaching component A. The apparatus 2000 may further include a scanning deflector 2008 configured to scan the beam with respect to the sample 2030 and an objective lens 2009 configured to focus the beam on the sample 2030. The apparatus 2000 may optionally further include a third multipole lens 2005 and a fourth multipole lens 2006. The third multipole lens 2005 is located downstream with respect to the aperture 2007. A fourth multipole lens 2006 is located downstream relative to the third multipole lens 2005. In the apparatus 2000 shown in Figure 2A, no power is applied to the first multipole lens 2003 or the second multipole lens 2004. The outline contour 2041 of the beam shows that only a small portion of the beam passes through the aperture 2007. That portion has an outline contour 2042.In the apparatus 2000 shown in Figure 2B, a first multipole lens 2003 and a second multipole lens 2004 are energized, which causes a larger portion of the beam to pass through an aperture 2007. The beam has a contour 2043. A third multipole lens 2005 and a fourth multipole lens 2006 may be used to shape the beam into a shape for precharging or for imaging.

[0037]

[0052] The multipole lenses 2003-2006 in the device 2000 may be electrostatic lenses. In an embodiment, the multipole lenses 2003-2006 each have at least four poles. For example, the multipole lenses 2003-2006 may be quadrupole lenses. FIG. 3 shows a schematic cross-section of a quadrupole lens as an example of the multipole lenses 2003-2006. The quadrupole lens has four poles 3001-3004. The poles 3001-3004 may each have a cross-sectional shape of a section of a ring. Each of the poles 3001-3004 may be separated from its neighboring pole by a gap or by a dielectric. The poles 3001 and 3003 are arranged opposite each other. The poles 3002 and 3004 are arranged opposite each other. In use, a positive voltage is applied to poles 3001 and 3003 and a negative voltage is applied to poles 3002 and 3004, the positive and negative voltages having the same absolute value. Assuming that the charged particles are negatively charged (e.g. the charged particles are electrons), the beam is elongated along a line connecting poles 3001 and 3003 and compressed along a line connecting poles 3002 and 3004. That is, the quadrupole lens causes the beam to have an elliptical cross section 3999. For example, the first multipole lens 2003 elongates the beam along a first direction and compresses the beam along a second direction different from the first direction (e.g. orthogonal to the first direction). The second multipole lens 2004 may elongate the beam along the second direction and compress the beam along the first direction.

[0038]

[0053] 4 shows schematic examples of cross-sectional shapes of the beam at aperture 2007 (left panel) and sample 2030 (right panel) in apparatus 2000 when current is applied to multipole lenses 2003-2006. Although the beam at sample 2030 does not have a uniform current density distribution across its cross section, it may still be used for pre-charging since beam uniformity is not critical for pre-charging purposes.

[0039]

[0054] FIG. 5A shows a schematic top view of another quadrupole lens as an example of the multipole lenses 2003-2006. FIG. 5B shows a schematic cross-sectional view of the quadrupole lens of FIG. 5A. This quadrupole lens has four prismatic or cylindrical poles 5001-5004. Each of the poles 5001-5004 may be separated from its neighboring poles by a gap or a dielectric. The poles 5001 and 5003 are arranged opposite each other. The poles 5002 and 5004 are arranged opposite each other. In use, a positive voltage is applied to the poles 5001 and 5003 and a negative voltage is applied to the poles 5002 and 5004, and the positive and negative voltages have the same absolute value. Assuming that the charged particles are negatively charged (eg, the charged particles are electrons), the beam is elongated along the line connecting poles 5001 and 5003 and narrowed along the line connecting poles 5002 and 5004.

[0040]

[0055] FIG. 6A shows a schematic diagram of a charged particle beam inspection in which a charged particle beam is used for both pre-charging and imaging, according to an embodiment. For convenience, the two directions x and y are defined in a reference coordinate system ("RF") that does not move relative to the sample. The x and y directions are mutually orthogonal. In this embodiment, the beam is in a suitable configuration for pre-charging and forms a spot 6001 on the sample. The spot 6001 has a diameter D1. The spot 6001 is scanned in the y direction by a length L, thereby pre-charging an area of ​​D1×L. The spot 6001 flashes back in the y direction by a length L and in the x direction by a suitable length (e.g., (D1-D2) / 2), and the beam changes to a suitable configuration for imaging to form a probe spot 6002 on the sample, or the beam changes to a suitable configuration for imaging to form a probe spot 6002 on the sample, and the probe spot 6002 flashes back in the y direction by a length L and in the x direction by a suitable length (e.g., (D1-D2) / 2). D2 is the diameter of the probe spot 6002. While the probe spot 6002 is scanned over an area of ​​D1×L, a signal representative of the interaction of the beam with the sample is stored from the probe spot 6002. For example, the probe spot 6002 may be scanned in the y direction by L, and then quickly return in the y direction by length L and in the x direction by D2. This back and forth scanning of the probe spot 6002 may be repeated until the probe spot 6002 has scanned the entire area of ​​D1×L. The probe spot 6002 quickly returns in the y direction by length L and in the x direction by a suitable length (e.g., (D1+D2) / 2), and the beam changes to a form suitable for pre-charging to form the spot 6001 on the sample, or the beam changes to a form suitable for pre-charging to form the spot 6001 on the sample, and the spot 6001 quickly returns in the y direction by length L and in the x direction by a suitable length (e.g., (D1+D2) / 2). This alternating scanning of the spot 6001 for precharging and the probe spot 6002 for imaging may be repeated to inspect an area on the sample. The dotted arrows represent a quick return movement of the spot 6001 or the probe spot 6002. The thick solid arrows represent the path of the spot 6001 along which some area of ​​the sample is precharged.The thin solid arrows represent the path of a probe spot 6002 over which some area of ​​the sample is imaged.

[0041]

[0056] Fig. 6B shows the path of the spot 6001 without showing the path of the probe spot 6002 in the alternate scanning of the spot 6001 for precharging and the probe spot 6002 for imaging in Fig. 6A. Fig. 6C shows the path of the probe spot 6002 without showing the path of the spot 6001 in the alternate scanning of the spot 6001 for precharging and the probe spot 6002 for imaging in Fig. 6A.

[0042]

[0057] FIG. 7A shows a schematic diagram of a charged particle beam inspection in which a charged particle beam is used for both pre-charging and imaging, according to an embodiment. For convenience, the two directions x and y are defined in a reference coordinate system ("RF") that does not move relative to the sample. The x and y directions are mutually orthogonal. In this embodiment, the beam is in a suitable configuration for pre-charging and forms a spot 6001 on the sample. The spot 6001 is scanned in the y direction by a length L, thereby pre-charging an area of ​​D1×L. The spot 6001 is snapped back in the x direction by a suitable length (e.g., (D1-D2) / 2) and the beam changes to a suitable configuration for imaging to form a probe spot 6002 on the sample, or the beam changes to a suitable configuration for imaging to form a probe spot 6002 on the sample, and the probe spot 6002 is snapped back in the x direction by a suitable length (e.g., (D1-D2) / 2). While the probe spot 6002 is scanned over an area of ​​D1×L, a signal representative of the interaction of the beam with the sample is stored from the probe spot 6002. For example, the probe spot 6002 may be scanned in the y direction by L and then flashed back in the y direction by length L and in the x direction by D2. This back and forth scanning of the probe spot 6002 may be repeated until the entire area of ​​D1×L is scanned. The probe spot 6002 flashes back in the x direction by a suitable length (e.g., (D1+D2) / 2) and the beam changes to a suitable form for precharging to form the spot 6001 on the sample, or the beam changes to a suitable form for precharging to form the spot 6001 on the sample, and the spot 6001 flashes back in the x direction by a suitable length (e.g., (D1+D2) / 2). This alternating scanning of the spot 6001 for precharging and the probe spot 6002 for imaging may be repeated to inspect an area on the sample. The dotted arrows represent a quick return movement of the spot 6001 or the probe spot 6002. The thick solid arrows represent the path of the spot 6001, where a portion of the sample area is precharged. The thin solid arrows represent the path of the probe spot 6002, where a portion of the sample area is imaged.

[0043]

[0058] Fig. 7B shows the path of the spot 6001 without showing the path of the probe spot 6002 in the alternate scanning of the spot 6001 for pre-charging and the probe spot 6002 for imaging in Fig. 7A. Fig. 7C shows the path of the probe spot 6002 without showing the path of the spot 6001 in the alternate scanning of the spot 6001 for pre-charging and the probe spot 6002 for imaging in Fig. 7A.

[0044]

[0059] FIG. 8A shows a schematic diagram of a charged particle beam inspection in which a charged particle beam is used for both pre-charging and imaging, according to an embodiment. For convenience, the two directions x and y are defined in a reference coordinate system ("RF") that does not move relative to the sample. The x and y directions are mutually orthogonal. In this embodiment, the beam is in a form suitable for pre-charging and forms a spot 6001 on the sample. The spot 6001 is scanned in the y direction by a length L, thereby pre-charging an area of ​​D1×L. The spot 6001 is quickly returned in the y direction by a length L and in the x direction by a length D1. The back and forth scanning of the spot 6001 is repeated until the entire area of ​​nD1×L (n is a positive integer) is pre-charged by the spot 6001. The spot 6001 moves in the y direction by a length L and then moves back in the x direction by a suitable length (e.g., (n-1)D1+(D1-D2) / 2) and the beam changes to a form suitable for imaging to form the probe spot 6002 on the sample, or the beam changes to a form suitable for imaging to form the probe spot 6002 on the sample and the probe spot 6002 moves back in the y direction by a length L and then moves back in the x direction by a suitable length (e.g., (n-1)D1+(D1-D2) / 2). While the probe spot 6002 is scanned over an area of ​​nD1×L, a signal representative of the interaction of the beam with the sample is stored from the probe spot 6002. For example, the probe spot 6002 may be scanned in the y direction by L and then moves back in the y direction by a length L and then moves back in the x direction by D2. This back and forth scanning of the probe spot 6002 may be repeated until the entire area of ​​nD1×L is scanned by the probe spot 6002. The dotted arrows represent a quick return movement of the spot 6001 or the probe spot 6002. The thick solid arrows represent the path of the spot 6001, where a portion of the sample area is precharged. The thin solid arrows represent the path of the probe spot 6002, where a portion of the sample area is imaged.

[0045]

[0060] Fig. 8B shows the path of the spot 6001 without showing the path of the probe spot 6002 in the alternate scanning of the spot 6001 for pre-charging and the probe spot 6002 for imaging in Fig. 8A. Fig. 8C shows the path of the probe spot 6002 without showing the path of the spot 6001 in the alternate scanning of the spot 6001 for pre-charging and the probe spot 6002 for imaging in Fig. 8A.

[0046]

[0061] FIG. 9 shows a schematic flow chart of a method for charged particle beam inspection according to an embodiment. In step 9010, the charged particle beam is set in a suitable configuration for precharging a sample. In step 9020, an area of ​​the sample is precharged using the charged particle beam in a suitable configuration for precharging. In step 9030, the same charged particle beam is set in a suitable configuration for imaging the sample. In step 9040, an area of ​​the sample is imaged using the charged particle beam in a suitable configuration for imaging. The flow may return to step 9010. Step 9030 may not occur immediately after step 9020. In an example where the charged particle beam is generated using the apparatus 2000 described above, setting the beam in a suitable configuration for precharging may include energizing the first multipole lens 2003 and the second multipole lens 2004, and optionally, if present, the third multipole lens 2005 and the fourth multipole lens 2006. Setting the beam into a configuration suitable for imaging may include de-energizing at least one of the first multipole lens 2003 and the second multipole lens 2004, and optionally, if present, at least one of the third multipole lens 2005 and the fourth multipole lens 2006.

[0047]

[0062] The embodiments may be further described using the following clauses. 1. An apparatus comprising: a charged particle radiation source configured to emit a charged particle beam along a primary beam axis of the apparatus; a focusing lens configured to focus the beam around a primary beam axis; Opening and A first multipole lens; The second multipole lens and Equipped with a first multipole lens located downstream with respect to the condenser lens and upstream with respect to the second multipole lens; The apparatus wherein a second multipole lens is located downstream relative to the first multipole lens and upstream relative to the aperture.

[0048] 2. 13. The apparatus of claim 1, further comprising a scanning deflector configured to scan the beam relative to the sample.

[0049] 3. 3. The apparatus of claim 1 or 2, further comprising an objective lens configured to focus the beam on the sample.

[0050] 4. The device described in any one of clauses 1 to 3, further comprising a third multipole lens and a fourth multipole lens, the third multipole lens being located downstream with respect to the opening, and the fourth multipole lens being located downstream with respect to the third multipole lens.

[0051] 5. 5. The apparatus of any one of clauses 1 to 4, wherein the first multipole lens and the second multipole lens are electrostatic lenses.

[0052] 6. 6. The apparatus of any one of clauses 1 to 5, wherein the first multipole lens and the second multipole lens each have at least four poles.

[0053] 7. 7. The apparatus of claim 6, wherein the poles each have a cross-sectional shape of a section of a ring.

[0054] 8. 7. The apparatus of claim 6, wherein each of the poles is prismatic or cylindrical.

[0055] 9. 7. The apparatus of claim 6, wherein each of the poles is separated from its neighboring pole by a gap or by a dielectric.

[0056] 10. 7. The apparatus of clause 6, wherein the poles are configured such that different voltages are applied to the poles.

[0057] 11. 11. The apparatus of any one of clauses 1 to 10, wherein a first multipole lens is configured to stretch the beam in a first direction and compress the beam in a second direction, and a second multipole lens is configured to stretch the beam in the second direction and compress the beam in the first direction.

[0058] 12. setting the charged particle beam in a first configuration suitable for precharging the sample; pre-charging an area of ​​the sample using the charged particle beam in a first configuration; setting the charged particle beam in a second configuration suitable for imaging the sample; imaging the area using the charged particle beam in a second configuration; A method comprising:

[0059] 13. The charged particle beam is an apparatus comprising: a charged particle radiation source configured to emit a charged particle beam along a primary beam axis of the apparatus; a focusing lens configured to focus the beam around a primary beam axis; Opening and A first multipole lens; The second multipole lens and Equipped with a first multipole lens located downstream with respect to the condenser lens and upstream with respect to the second multipole lens; a second multipole lens located downstream with respect to the first multipole lens and upstream with respect to the aperture; 13. The method of claim 12, generated in an apparatus.

[0060] 14. 14. The method of claim 13, wherein configuring the beam to a first configuration includes energizing a first multipole lens and a second multipole lens.

[0061] 15. 14. The method of claim 13, wherein setting the beam to the second configuration includes de-energizing at least one of the first multipole lens and the second multipole lens.

[0062] 16. 14. The method of claim 13, wherein the apparatus further comprises a third multipole lens and a fourth multipole lens, the third multipole lens being located downstream relative to the aperture and the fourth multipole lens being located downstream relative to the third multipole lens.

[0063] 17. 17. The method of claim 16, wherein configuring the beam to the first configuration includes energizing a third multipole lens and a fourth multipole lens.

[0064] 18. 17. The method of claim 16, wherein setting the beam to the second configuration includes de-energizing at least one of the third multipole lens and the fourth multipole lens.

[0065] 19. A computer program product comprising a non-transitory computer readable medium having instructions recorded thereon, the instructions, when executed by a computer, performing a method according to any one of clauses 12 to 18.

[0066]

[0063] Although the concepts disclosed in this specification may be used for inspection of samples such as silicon wafers or patterning devices such as chrome on glass, it should be understood that the disclosed concepts may be used with any type of sample, for example in the inspection of samples other than silicon wafers.

[0067]

[0064] The above description is intended to be illustrative rather than limiting. Thus, it will be apparent to one skilled in the art that modifications can be made as described without departing from the scope of the claims set forth below.

Claims

1. An apparatus comprising: an electron source configured to emit an electron beam along a primary beam axis of the apparatus; a focusing lens configured to focus the electron beam around the primary beam axis; an aperture; a first multipole lens; and a second multipole lens; The apparatus, wherein the first multipole lens and the second multipole lens are configured to adjust the amount of the electron beam incident on the aperture to a first amount when in a first configuration and to a second amount when in a second configuration, thereby adjusting the flow of the electron beam incident on a sample.

2. The apparatus of claim 1 , further comprising a scanning deflector configured to scan the beam relative to a sample.

3. The apparatus of claim 1 , further comprising an objective lens configured to focus the beam onto a sample.

4. Further comprising a third multipole lens and a fourth multipole lens; The apparatus of claim 1 , wherein the third multipole lens is located downstream relative to the aperture, and the fourth multipole lens is located downstream relative to the third multipole lens.

5. The apparatus of claim 1 , wherein the first multipole lens and the second multipole lens are electrostatic lenses.

6. The apparatus of claim 1 , wherein the first multipole lens and the second multipole lens each have at least four poles.

7. 7. The apparatus of claim 6, wherein the poles each have a cross-sectional shape of a section of a ring.

8. 7. The apparatus of claim 6, wherein each of the poles is prismatic or cylindrical.

9. 7. The apparatus of claim 6, wherein each of the poles is separated from its neighboring pole by a gap or by a dielectric.

10. The apparatus of claim 6 , wherein the poles are configured such that different voltages are applied to the poles.

11. the first multipole lens is configured to stretch the beam in a first direction and compress the beam in a second direction; The apparatus of claim 1 , wherein the second multipole lens is configured to stretch the beam in the second direction and compress the beam in the first direction.

12. 1. A non-transitory computer readable medium having stored thereon a set of instructions executable by at least one processor of a computer system to cause the computer system to perform operations for imaging a sample using an apparatus comprising a charged particle source, a collector lens, an aperture, a first multipole lens, and a second multipole lens, the non-transitory computer readable medium comprising: The operation is setting a charged particle beam in a first configuration suitable for precharging the sample; pre-charging an area of ​​the sample using the charged particle beam in the first configuration; configuring the charged particle beam in a second configuration suitable for imaging the sample; imaging the area using the charged particle beam in the second configuration; and configuring the first multipole lens and the second multipole lens to adjust a flow of the charged particle beam incident on the sample by adjusting a first amount of the charged particle beam incident on the aperture of the device when in a first configuration and a second amount when in a second configuration; A non-transitory computer-recorded medium,

13. 13. The non-transitory computer-readable storage medium of claim 12, wherein the operations further comprise configuring the charged particle beam in the first configuration by energizing the first multipole lens and the second multipole lens of the apparatus.

14. 13. The non-transitory computer-readable storage medium of claim 12, wherein the operation includes setting the charged particle beam to the second configuration by de-energizing at least one of the first multipole lens and the second multipole lens of the apparatus.

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