# US 2017/0287675 A1 · Method and System for Charge Control for Imaging Floating Metal Structures on Non-Conducting Substrates > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0287675 A1 - Document ID: US20170287675A1 - Status: Published application - Kind: A1 - Application number: 15/387,388 - Filed: 2016-12-21 - Published: 2017-10-05 - Earliest claimed: 2016-04-04 - Assignees: KLA-Tencor Corporation - Applicants: KLA-Tencor Corporation - Inventors: Arjun Hegde; Luca Grella; Christopher Sears - Web page: https://patentgrep.com/patent/US20170287675A1 ## CPC - H01J 37/153: Electron-optical or ion-optical arrangements for the correction of image defects, e.g. stigmators - H01J 37/10: Lenses - H01J 37/18: Vacuum locks {; Means for obtaining or maintaining the desired pressure within the vessel} - H01J 37/20: Means for supporting or positioning the object or the material; Means for adjusting diaphragms or lenses associated with the support - H01J 37/244: Detectors; Associated components or circuits therefor - H01J 37/265: {Controlling the tube; circuit arrangements adapted to a particular application not otherwise provided, e.g. bright-field-dark-field illumination} - H01J 37/28: with scanning beams {(H01J37/268, H01J37/292, H01J37/2955 take precedence)} - H01J 2237/0044: of objects being observed or treated - H01J 2237/0048: Charging arrangements - H01J 2237/103: characterised by lens type - H01J 2237/20285: computer-controlled - H01J 2237/221: Image processing - H01J 2237/24592: Inspection and quality control of devices - H01J 2237/2809: characterised by the imaging problems involved - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract A scanning electron microscopy system is disclosed. The system includes a sample stage configured to secure a sample having conducting structures disposed on an insulating substrate. The system includes an electron-optical column including an electron source configured to generate a primary electron beam and a set of electron-optical elements configured to direct at least a portion of the primary electron beam onto a portion of the sample. The system includes a detector assembly configured to detect electrons emanating from the surface of the sample. The system includes a controller communicatively coupled to the detector assembly. The controller is configured to direct the electron-optical column and stage to perform, with the primary electron beam, an alternating series of image scans and flood scans of the portion of the sample, wherein each of the flood scans are performed sequential to one or more of the imaging scans. ## Claims ### Claim 1 A scanning electron microscopy apparatus comprising: a sample stage configured to secure a sample including one or more conducting structures disposed on insulating material; an electron-optical column comprising: an electron source configured to generate a primary electron beam; and a set of electron-optical elements configured to direct at least a portion of the primary electron beam onto a portion of the sample; a detector assembly configured to detect electrons emanating from the surface of the sample; and a controller communicatively coupled to the detector assembly, the controller including one or more processors configured to execute program instructions maintained in memory, the program instructions configured to cause the one or more processors to: direct the electron-optical column to perform, with the primary electron beam, an alternating series of image scans and flood scans of the portion of the sample, wherein each of the flood scans are performed sequential to one or more of the imaging scans. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the series of image scans is used to form a final image. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the series of flood scans is discarded. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein one or more imaging frames are acquired at a first landing energy. ### Claim 5 (depends on 1) The apparatus of claim 1, wherein one or more flood frames are acquired at an additional landing energy. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein the set of electron-optical elements comprises: a condenser lens. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the set of electron-optical elements comprises: an objective lens. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein the set of electron-optical elements comprises: a set of scanning elements. ### Claim 9 (depends on 1) The apparatus of claim 1, wherein the electron beam source comprises: one or more electron guns. ### Claim 10 (depends on 1) The apparatus of claim 1, wherein the detector assembly comprises: at least one of a secondary electron detector or a backscattered electron detector. ### Claim 11 (depends on 1) The apparatus of claim 1, further comprising: bias control circuitry configured to control a bias of the stage. ### Claim 12 (depends on 1) The apparatus of claim 1, wherein the controller is configured to adjust at least one of one or more one or more components of the electron-optical column or the bias control circuitry in order to perform at least one of the imaging scans and the flood scans. ### Claim 13 (depends on 1) The apparatus of claim 1, further comprising: a vacuum system. ### Claim 14 A scanning electron microscopy apparatus comprising: a sample stage configured to secure a sample including one or more conducting structures disposed on insulating material; an electron-optical column comprising: an electron source configured to generate a primary electron beam; and a set of electron-optical elements configured to direct at least a portion of the primary electron beam onto a portion of the sample; a detector assembly configured to detect electrons emanating from the surface of the sample; and a controller communicatively coupled to the detector assembly, the controller including one or more processors configured to execute program instructions maintained in memory, the program instructions configured to cause the one or more processors to: direct the electron-optical column to perform, with the primary electron beam, an alternating series of exposures of the portion of the sample, wherein the alternating series of exposures includes a first set of exposures performed at a first electron landing energy and an additional set of exposures performed at an additional landing energy less than the first landing energy, wherein each of the exposures of the additional set of exposures are performed sequential to one or more exposures of the first set of exposures. ### Claim 15 (depends on 14) The apparatus of claim 14, wherein the alternating series of exposures of the portion of the sample includes a series of N exposures alternating between the first electron landing energy and the additional electron landing energy. ### Claim 16 (depends on 14) The apparatus of claim 14, wherein the alternating series of exposures of the portion of the sample causes surface charge neutralization at a surface of the sample. ### Claim 17 (depends on 14) The apparatus of claim 14, wherein the first landing energy is equal to or greater than 50 eV. ### Claim 18 (depends on 14) The apparatus of claim 14, wherein the additional landing energy is less than 1 eV. ### Claim 19 (depends on 14) The apparatus of claim 14, wherein the controller directs the electron-optical column to achieve the first landing energy of the primary electron beam by maintaining the sample at a voltage at least 5 kV more positive than a voltage of a cathode of the electron source. ### Claim 20 (depends on 14) The apparatus of claim 14, wherein the controller directs the electron-optical column to achieve the additional landing energy of the primary electron beam by maintaining the sample at a voltage less than 10 V more positive than a voltage of a cathode of the electron source. ### Claim 21 (depends on 14) The apparatus of claim 14, wherein one or more imaging frames are acquired at the first landing energy. ### Claim 22 (depends on 14) The apparatus of claim 14, wherein one or more flood frames are acquired at the additional landing energy. ### Claim 23 (depends on 14) The apparatus of claim 14, wherein a single cathode of the electron source generates the primary electron beam having the first landing energy and the primary electron beam having the additional landing energy. ### Claim 24 (depends on 14) The apparatus of claim 14, wherein a single cathode of the electron source generates the primary electron beam having the first landing energy and the primary electron beam having the additional landing energy. ### Claim 25 (depends on 14) The apparatus of claim 14, wherein the set of electron-optical elements comprises: a condenser lens. ### Claim 26 (depends on 14) The apparatus of claim 14, wherein the set of electron-optical elements comprises: an objective lens. ### Claim 27 (depends on 14) The apparatus of claim 14, wherein the set of electron-optical elements comprises: a set of scanning elements. ### Claim 28 (depends on 14) The apparatus of claim 14, wherein the electron beam source comprises: one or more electron guns. ### Claim 29 (depends on 14) The apparatus of claim 14, wherein the detector assembly comprises: at least one of a secondary electron detector or a backscattered electron detector. ### Claim 30 (depends on 14) The apparatus of claim 14, further comprising: bias control circuitry configured to control a bias of the stage. ### Claim 31 (depends on 14) The apparatus of claim 14, wherein the controller is configured to adjust at least one of one or more one or more components of the electron-optical column or the bias control circuitry in order to establish at least one of the first landing energy or the additional landing energy. ### Claim 32 (depends on 14) The apparatus of claim 14, further comprising: a vacuum system. ### Claim 33 A scanning electron microscopy apparatus comprising: a sample stage configured to secure a sample including one or more conducting structures disposed on insulating material; an electron-optical column comprising: an electron source configured to generate a primary electron beam; and a set of electron-optical elements configured to direct at least a portion of the primary electron beam onto a portion of the sample; a detector assembly configured to detect electrons emanating from the surface of the sample; and a controller communicatively coupled to the detector assembly, the controller including one or more processors configured to execute program instructions maintained in memory, the program instructions configured to cause the one or more processors to: direct the electron-optical column to perform, with the primary electron beam, an alternating series of exposures of the portion of the sample, wherein the alternating series of exposures includes a first set of exposures performed at a first electron extraction field and an additional set of exposures performed at an additional electron extraction field, wherein each of the exposures of the additional set of exposures are performed sequential to one or more exposures of the first set of exposures. ### Claim 34 (depends on 33) The apparatus of claim 33, wherein the alternating series of exposures of the portion of the sample includes a series of N exposures alternating between the first electron extraction field and the additional electron extraction field. ### Claim 35 (depends on 33) The apparatus of claim 33, wherein a landing energy is held constant during image acquisition. ### Claim 36 (depends on 33) The apparatus of claim 33, wherein the alternating series of exposures of the portion of the sample causes surface charge neutralization at a surface of the sample. ### Claim 37 (depends on 33) The apparatus of claim 33, wherein the first electron extraction field is larger than the additional electron extraction field. ### Claim 38 (depends on 37) The apparatus of claim 37, wherein the first electron extraction field is between 100 and 3000 Volts/mm. ### Claim 39 (depends on 37) The apparatus of claim 37, wherein the additional electron extraction field is less than 0 Volts/mm. ### Claim 40 (depends on 33) The apparatus of claim 33, wherein the first electron extraction field is established by maintaining an objective lens of the electron-optical column at a voltage substantially more positive than the voltage of the sample. ### Claim 41 (depends on 33) The apparatus of claim 33, wherein the additional electron extraction field is established by maintaining an objective lens of the electron-optical column at a voltage more negative than the voltage of the sample. ### Claim 42 (depends on 41) The apparatus of claim 41 wherein electrons repelled by the objective lens maintain at a voltage more negative than the voltage of the sample repels electrons from the objective and causes surface charge neutralization of the sample. ### Claim 43 (depends on 33) The apparatus of claim 33, wherein one or more imaging frames are acquired at the first electron extraction field. ### Claim 44 (depends on 33) The apparatus of claim 33, wherein one or more flood frames are acquired at the additional electron extraction field. ### Claim 45 (depends on 33) The apparatus of claim 33, wherein the set of electron-optical elements comprises: a condenser lens. ### Claim 46 (depends on 33) The apparatus of claim 33, wherein the set of electron-optical elements comprises: an objective lens. ### Claim 47 (depends on 33) The apparatus of claim 33, wherein the set of electron-optical elements comprises: a set of scanning elements. ### Claim 48 (depends on 33) The apparatus of claim 33, wherein the electron beam source comprises: one or more electron guns. ### Claim 49 (depends on 33) The apparatus of claim 33, wherein the detector assembly comprises: at least one of a secondary electron detector or a backscattered electron detector. ### Claim 50 (depends on 33) The apparatus of claim 33, further comprising: bias control circuitry configured to control a bias of the stage. ### Claim 51 (depends on 33) The apparatus of claim 33, further comprising: a vacuum system. ### Claim 52 A method comprising: performing, with an electron beam, an alternating series of image scans and flood scans of a portion of a sample, wherein each of the flood scans are performed sequential to one or more of the imaging scans. ### Claim 53 A method comprising: performing, with an electron beam, an alternating series of exposures of a portion of a sample, wherein the alternating series of exposures includes a first set of exposures performed at a first electron landing energy and an additional set of exposures performed at an additional landing energy less than the first landing energy, wherein each of the exposures of the additional set of exposures are performed sequential to one or more exposures of the first set of exposures. ### Claim 54 A method comprising: performing, with an electron beam, an alternating series of exposures of a portion of a sample, wherein the alternating series of exposures includes a first set of exposures performed at a first electron extraction field and an additional set of exposures performed at an additional electron extraction field, wherein each of the exposures of the additional set of exposures are performed sequential to one or more exposures of the first set of exposures.