# US 6,720,556 B2 · Electron spectroscopy employing controlled surface charging > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,720,556 B2 - Document ID: US6720556B2 - Status: Granted - Kind: B2 - Application number: 09/847,583 - Filed: 2001-05-03 - Published: 2002-02-21 - Granted: 2004-04-13 - Earliest claimed: 2000-07-06 - Assignees: Yeda Research and Development Co. Ltd. - Inventors: Hagai Cohen; Israel Rubinstein - Web page: https://patentgrep.com/patent/US6720556B2 ## CPC - G01N 23/227: Measuring photoelectric effect, e.g. photoelectron emission microscopy [PEEM] - B82Y 15/00: Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors - H01J 2237/2522: of electrons (ESCA, XPS) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract A method of examining a sample, including: performing a first spectroscopic analysis of a surface portion of the sample when the sample surface portion is in a first electrical charge state; placing the sample surface portion in a second electrical charge state that is different from the first electrical charge state and performing a second spectroscopic analysis of the surface portion of the sample when the sample surface portion is in the second electrical charge state; and comparing the first spectroscopic analysis result with the second spectroscopic analysis result to obtain at least one of structural and electrical information about the sample. ## Claims ### Claim 1 A method of examining a sample, comprising: performing a first spectroscopic analysis of a surface portion of the sample when the sample surface portion is in a first electrical charge state; placing the sample surface portion in a second electrical charge state that is different from the first electrical charge state and performing a second spectroscopic analysis of the surface portion of the sample when the sample surface portion is in the second electrical charge state; and comparing the first spectroscopic analysis result with the second spectroscopic analysis result to obtain at least one of structural and electrical information about the sample, wherein the first and second electrical charge states are given values that enable information to be obtained about sample structural features having dimensions down to 1 nm. ### Claim 2 (depends on 1) The method according to claim 1, wherein the spectroscopic analyses are performed with X-ray photoelectron spectroscopy (XPS). ### Claim 3 (depends on 1) The method according to claim 1, wherein said placing step comprises supplying an excess negative charge to the surface of the sample surface portion. ### Claim 4 (depends on 3) The method according to claim 3 wherein the excess negative charge is supplied by an electron flood gun. ### Claim 5 (depends on 3) The method according to claim 3 wherein the first electrical charge state is a charge neutral state. ### Claim 6 (depends on 1) The method according to claim 1 wherein the second spectroscopic analysis is performed identically to the first spectroscopic analysis. ### Claim 7 (depends on 1) The method according to claim 1 wherein the sample surface is composed of isolated regions of a first material separated by a second material, the materials being selected for causing the result of the first spectroscopic analysis to differ from the result of the second spectroscopic analysis in a manner to provide information about the distribution of the isolated regions or the sample surface portion. ### Claim 8 (depends on 7) The method according to claim 7 wherein the first material is a dielectric and the second material is electrically conductive. ### Claim 9 (depends on 1) The method according to claim 1 wherein the sample is composed of a plurality of superposed layers and at least one of the layers contains a substance selected for causing the result of the first spectroscopic analysis to differ from the result of the second spectroscopic analysis in a manner to provide information about the position of the at least one of the layers in the plurality of superposed layers. ### Claim 10 A method of examining a sample, comprising: performing a first spectroscopic analysis of a surface portion of the sample when the sample surface portion is in a first electrical charge state; placing the sample surface portion in a second electrical charge state that is different from the first electrical charge state and performing a second spectroscopic analysis of the surface portion of the sample when the sample surface portion is in the second electrical charge state; and comparing the first spectroscopic analysis result with the second spectroscopic analysis result to obtain at least one of structural and electrical information about the sample, wherein each spectroscopic analysis result contains data identifying a characteristic of the spectral response for each of at least two elements contained in the sample, and said step of comparing includes determining, for each of the at least two elements contained in the sample, a difference between the first spectroscopic analysis result and the second spectroscopic analysis result and correlating the differences determined in the determining step for the at least two elements to provide a quantitative value of a characteristic of the sample, and the first and second electrical charge states are given values that enable information to be obtained about sample structural features having dimensions down to 1 nm. ### Claim 11 (depends on 10) The method according to claim 10, wherein the spectroscopic analyses are performed with X-ray photoelectron spectroscopy (XPS). ### Claim 12 (depends on 10) The method according to claim 10, wherein said placing step comprises supplying an excess negative charge to the surface of the sample surface portion. ### Claim 13 (depends on 12) The method according to claim 12 wherein the excess negative charge is supplied by an electron flood gun. ### Claim 14 (depends on 12) The method according to claim 12 wherein the first electrical charge state is a charge neutral state. ### Claim 15 (depends on 10) The method according to claim 10 wherein the second spectroscopic analysis is performed identically to the first spectroscopic analysis. ### Claim 16 (depends on 10) The method according to claim 10 wherein the sample surface is composed of isolated regions of a first material separated by a second material, the materials being selected for causing the result of the first spectroscopic analysis to differ from the result of the second spectroscopic analysis in a manner to provide information about the distribution of the isolated regions or the sample surface portion. ### Claim 17 (depends on 16) The method according to claim 16 wherein the first material is a dielectric and the second material is electrically conductive. ### Claim 18 (depends on 10) The method according to claim 10 wherein the sample is composed of a plurality of superposed layers and at least one of the layers contains a substance selected for causing the result of the first spectroscopic analysis to differ from the result of the second spectroscopic analysis in a manner to provide information about the position of the at least one of the layers in the plurality of superposed layers. ### Claim 19 Apparatus for examining a sample, comprising: a spectroscopic analysis instrument including a component that places a surface portion of the sample in different electrical charge states, for performing a first spectroscopic analysis of a surface portion of the sample when the sample surface portion is in a first electrical charge state and performing a second spectroscopic analysis of the surface portion of the sample when the sample surface portion is in a second electrical charge state different from the first electrical charge state; and an arithmetic unit coupled to said instrument to compare the first spectroscopic analysis result with the second spectroscopic analysis result to obtain at least one of structural and electrical information about the sample, wherein each spectroscopic analysis result contains data identifying a characteristic of the spectral response for each of at least two elements contained in the sample, and the comparison performed by the arithmetic unit includes the steps of determining, for each of the at least two elements contained in the sample, a difference between the first spectroscopic analysis result and the second spectroscopic analysis result and correlating the differences determined in the determining step for the at least two elements to provide a quantitative value of a characteristic of the sample, and the first and second electrical charge states are given values that enable information to be obtained about sample structural features having dimensions down to 1 nm. ### Claim 20 (depends on 19) The apparatus according to claim 19, wherein the instrument is a X-ray photoelectron spectroscopy (XPS) instrument. ### Claim 21 (depends on 19) The apparatus according to claim 19, wherein said component supplies an excess negative charge to the surface of the sample surface portion. ### Claim 22 (depends on 21) The apparatus according to claim 21 wherein said component comprises an electron flood gun.