# US 12,763,281 B2 · Method to more precisely calibrate the mechanical tilt and rotation angles of an SEM column > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,763,281 B2 - Document ID: US12763281B2 - Status: Granted - Kind: B2 - Application number: 18/231,534 - Filed: 2023-08-08 - Published: 2025-02-13 - Granted: 2026-10-13 - Earliest claimed: 2023-08-08 - Assignees: Applied Materials Israel Ltd. - Applicants: Applied Materials Israel Ltd. - Inventors: Yehuda Zur; Gal Bruner - Web page: https://patentgrep.com/patent/US12763281B2 ## CPC - H01J 37/222: {Image processing arrangements associated with the tube} - H01J 37/1478: {Beam tilting means, i.e. for stereoscopy or for beam channelling} - H01J 37/28: with scanning beams {(H01J37/268, H01J37/292, H01J37/2955 take precedence)} - H01J 2237/2815: Depth profile - H01J 2237/2826: Calibration - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract A method of determining a depth of a feature formed in a first region of a sample, by: positioning a test structure with known dimensions in a processing chamber having a charged particle column tilted at a first tilt angle and first rotational angle; determining the first tilt angle and first rotational angle by: taking an image of the test structure with the charged particle column tilted at the first tilt angle and the first rotational angle, measuring, based on the image, distances between multiple edges of the test structure aligned with each other along a vector, determining ratios between the measured distances, and determining a calculated tilt angle and a calculated rotational angle of charged particle column from the ratios and the known dimensions of the structure; transferring the test structure out of the processing chamber and positioning the sample in the processing chamber such that the first region is under a field of view of the charged particle column; taking a first image of the feature with the column tilted at the first tilt angle and first rotational angle and taking a second image of the feature with the column is tilted at a second tilt angle, different than the first tilt angle, and a second rotational angle; and using stereoscopic measurement techniques to determine the depth of the feature based on the first and second images and the calculated tilt angle and calculated rotational angle. ## Claims ### Claim 1 A method of determining a depth of a feature formed in a first region of a sample, the method comprising: positioning a test structure with known dimensions in a processing chamber having a charged particle column tilted at a first tilt angle and first rotational angle; determining the first tilt angle and first rotational angle by: taking an image of the test structure with the charged particle column tilted at the first tilt angle and the first rotational angle; measuring, based on the image, distances between multiple edges of the test structure aligned with each other along a vector; determining ratios between the measured distances; and determining a calculated tilt angle and a calculated rotational angle of charged particle column from the ratios and the known dimensions of the structure, wherein calculations to determine the tilt angle and rotation angles are independent of magnification calibration and require neither determination nor assumption of a magnification or scale factor relating image pixels to real-world distances; transferring the test structure out of the processing chamber and positioning the sample in the processing chamber such that the first region is under a field of view of the charged particle column; taking a first image of the feature with the column tilted at the first tilt angle and first rotational angle and taking a second image of the feature with the column is tilted at a second tilt angle, different than the first tilt angle, and a second rotational angle; and using stereoscopic measurement techniques to determine the depth of the feature based on the first and second images and the calculated tilt angle and calculated rotational angle. ### Claim 2 (depends on 1) The method of determining a depth of a feature set forth in claim 1 wherein the test structure comprises: a first set of edges spaced apart from each other and aligned with an X-axis such that, when the first set of edges is projected onto a two dimensional space, a first vector normal to the X-axis intersects each edge in the first set; and a second set of edges spaced apart from each other and aligned with a Y-axis such that, when the second set of edges is projected onto a two dimensional space, a second vector normal to the Y-axis intersects each edge in the second set. ### Claim 3 (depends on 2) The method of determining a depth of a feature set forth in claim 2 wherein the first set of edges comprises three edges and the second set of edges comprises four edges. ### Claim 4 (depends on 3) The method of determining a depth of a feature set forth in claim 3 wherein the test structure is a trapezoidal prism and the distances measured between multiple edges includes a distance of a width of a top surface of the trapezoidal prism, a length of a front surface of the prism, and a length of a side surface of the prism. ### Claim 5 (depends on 4) The method of determining a depth of a feature set forth in claim 4 wherein: the first set of edges includes first, second and third edges and the second set of edges includes fourth, fifth, sixth and seventh edges; and determining ratios includes determining a first ratio between a distance between the first and second edges to a distance between the second and third edges and a second ratio between a distance between the fourth and fifth edges to a distance between the sixth and seventh edges. ### Claim 6 (depends on 1) The method of determining a depth of a feature set forth in claim 1 wherein the second rotational angle is equal to the first rotational angle. ### Claim 7 (depends on 1) The method of determining a depth of a feature set forth in claim 1 wherein the first tilt angle is approximately 45° to a top surface of the sample and the second tilt angle is approximately normal to the surface of the sample. ### Claim 8 (depends on 1) The method of determining a depth of a feature set forth in claim 1 wherein the charged particle column is a scanning electron microscope (SEM) column. ### Claim 9 (depends on 1) The method of determining a depth of a feature set forth in claim 1 wherein the sample is a semiconductor wafer. ### Claim 10 (depends on 1) The method of determining a depth of a feature set forth in claim 1 wherein the processing chamber is a vacuum chamber that includes both a focused ion beam (FIB) column and a scanning electron microscope (SEM) column. ### Claim 11 A method of precisely calibrating mechanical tilt and rotation angles of a charged particle column, the method comprising: positioning a test structure with known dimensions in a processing chamber having a charged particle column tilted at a first tilt angle and first rotational angle; determining the first tilt angle and first rotational angle by: taking an image of the test structure with the charged particle column tilted at the first tilt angle and the first rotational angle; measuring, based on the image, distances between multiple edges of the test structure aligned with each other along a vector; determining ratios between the measured distances; and determining a calculated tilt angle and a calculated rotational angle of charged particle column from the ratios and the known dimensions of the structure, wherein calculations to determine the calculated tilt and rotation angles are independent of magnification calibration and require neither determination nor assumption of a magnification or scale factor relating image pixels to real-world distances. ### Claim 12 (depends on 11) The method of calibrating mechanical tilt and rotation angles of a charged particle column set forth in claim 11 wherein the test structure comprises: a first set of edges spaced apart from each other and aligned with an X-axis such that, when the first set of edges is projected onto a two dimensional space, a first vector normal to the X-axis intersects each edge in the first set; and a second set of edges spaced apart from each other and aligned with a Y-axis such that, when the second set of edges is projected onto a two dimensional space, a second vector normal to the Y-axis intersects each edge in the second set. ### Claim 13 (depends on 12) The method of determining a depth of a feature set forth in claim 12 wherein the first set of edges comprises three edges and the second set of edges comprises four edges. ### Claim 14 (depends on 12) The method of calibrating mechanical tilt and rotation angles of a charged particle column set forth in claim 12 wherein the test structure is a trapezoidal prism and the distances measured between multiple edges includes a distance of a width of a top surface of the trapezoidal prism, a length of a front surface of the prism, and a length of a side surface of the prism. ### Claim 15 (depends on 1) The method of determining a depth of a feature set forth in claim 1 wherein the first tilt angle is approximately 45° to the surface of the sample. ### Claim 16 A system for determining a depth of a hole formed in a first region of a sample, the system comprising: a vacuum chamber; a sample support configured to hold a sample within the vacuum chamber during a milling process; a charged particle beam column configured to direct a charged particle beam into the vacuum chamber; a processor and a memory coupled to the processor, the memory including a plurality of computer-readable instructions that, when executed by the processor, cause the system to: position a test structure with known dimensions on the sample support with the charged particle column tilted at a first tilt angle and first rotational angle; determine the first tilt angle and first rotational angle by: taking an image of the test structure with the charged particle column tilted at the first tilt angle and the first rotational angle; measuring, based on the image, distances between multiple edges of the test structure aligned with each other along a vector; determining ratios between the measured distances; and determining a calculated tilt angle and a calculated rotational angle of charged particle column from the ratios and the known dimensions of the structure, wherein calculations to determine the tilt angle and rotation angles are independent of magnification calibration and require neither determination nor assumption of a magnification or scale factor relating image pixels to real-world distances; transfer the test structure out of the processing chamber and positioning the sample in the processing chamber such that the first region is under a field of view of the charged particle column; take a first image of the feature with the column tilted at the first tilt angle and first rotational angle and taking a second image of the feature with the column is tilted at a second tilt angle, different than the first tilt angle, and a second rotational angle; and use stereoscopic measurement techniques to determine the depth of the hole based on the first and second images and the calculated tilt angle and calculated rotational angle. ### Claim 17 (depends on 16) The system for determining a depth of a hole set forth in claim 16 wherein the test structure comprises: a first set of edges spaced apart from each other and aligned with an X-axis such that, when the first set of edges is projected onto a two dimensional space, a first vector normal to the X-axis intersects each edge in the first set; and a second set of edges spaced apart from each other and aligned with a Y-axis such that, when the second set of edges is projected onto a two dimensional space, a second vector normal to the Y-axis intersects each edge in the second set. ### Claim 18 (depends on 16) The system for determining a depth of a hole set forth in claim 16 wherein the test structure is a trapezoidal prism and the distances measured between multiple edges includes a distance of a width of a top surface of the trapezoidal prism, a length of a front surface of the prism, and a length of a side surface of the prism. ### Claim 19 (depends on 16) The system for determining a depth of a hole set forth in claim 16 wherein the charged particle column is a scanning electron microscope (SEM) column that directs an electron beam into the chamber. ### Claim 20 (depends on 16) The system for determining a depth of a hole set forth in claim 16 wherein the processing chamber is a vacuum chamber that includes both a focused ion beam (FIB) column and a scanning electron microscope (SEM) column.