# US 10,478,936 B2 · Method and apparatus for measuring surface properties of polishing pad > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,478,936 B2 - Document ID: US10478936B2 - Status: Granted - Kind: B2 - Application number: 14/974,898 - Filed: 2015-12-18 - Published: 2016-06-30 - Granted: 2019-11-19 - Earliest claimed: 2014-12-26 - Assignees: Ebara Corporation; Kyushu Institute of Technology - Applicants: Ebara Corporation; Kyushu Institute of Technology - Inventors: Hisanori Matsuo; Yoshihiro Mochizuki; Keisuke Suzuki; Takahiro Tajiri; Panart Khajornrungruang - Web page: https://patentgrep.com/patent/US10478936B2 ## CPC - B24B 37/005: Control means for lapping machines or devices - B24B 49/12: involving optical means - G01N 21/55: Specular reflectivity - G01N 2021/4742: {comprising optical fibres} - G01N 2201/06113: Coherent sources; lasers - G01N 2201/0826: Fibre array at source, distributing - B24B: MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING (grinding of gear teeth B23F, of screw-threads B23G1/36; by electro-erosion B23H; abrasive or related blasting B24C; tools for grinding, buffing or sharpening B24D; polishing compositions C09G1/00; abrasives C09K3/14; electrolytic etching or polishing C25F3/00; grinding arrangements for use on assembled railway tracks E01B31/17); DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS - 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) ## Abstract A polishing pad surface property measuring method which can measure surface properties of a polishing pad that reflect CMP performance by applying a laser beam to the polishing pad at a plurality of incident angles is disclosed. The method includes applying a laser beam to a surface of the polishing pad, and receiving light reflected by the surface of the polishing pad and performing Fourier transform on the received light to determine surface properties of the polishing pad. The laser beam is applied to the polishing pad at a plurality of incident angles. ## Claims ### Claim 1 A method of measuring surface properties of a polishing pad, comprising: swinging a light source to apply a laser beam to a surface of a polishing pad at a plurality of incident angles, wherein the plurality of incident angles are different from each other; receiving light reflected by the surface of the polishing pad at a plurality of reflection angles; and performing a Fourier transform on the received light reflected at the plurality of reflection angles to determine surface properties of the polishing pad. ### Claim 2 (depends on 1) The method of measuring surface properties of a polishing pad according to claim 1, wherein the plurality of incident angles of the laser beam are selected from an angular range greater than the Brewster angle for the material of the polishing pad as a measuring object. ### Claim 3 (depends on 1) The method of measuring surface properties of a polishing pad according to claim 1, wherein the plurality of incident angles of the laser beam are selected depending on the material of the polishing pad as a measuring object, dressing conditions for the surface of the polishing pad, and the type of a dresser member for dressing the polishing pad. ### Claim 4 An apparatus configured to measure surface properties of a polishing pad, comprising: an optical system configured to apply a laser beam to a polishing pad at at least two different incident angles; and a processing device configured to determine surface properties of the polishing pad by performing a Fourier transform on light reflected by the polishing pad and received by the optical system; wherein the optical system comprises: a light source configured to emit the laser beam; a first mirror configured to apply the laser beam emitted from the light source to the polishing pad at a first incident angle; a second mirror disposed at a second position lower than a first position of the first mirror and configured to apply the laser beam emitted from the light source to the polishing pad at a second incident angle; at least two light receivers configured to receive the light reflected by the surface of the polishing pad at a first reflection angle corresponding to the first incident angle and at a second reflection angle corresponding to the second incident angle; and wherein the laser beam emitted from the light source passes through the first mirror and is refracted by the first mirror, and the refracted light is applied to the second mirror; wherein the Fourier transform is performed on the received light reflected at the first and second reflection angles to determine the surface properties of the polishing pad by the processing device. ### Claim 5 (depends on 4) The apparatus configured to measure surface properties of a polishing pad according to claim 4, wherein the at least one light receiver comprises a CCD element or a CMOS element. ### Claim 6 (depends on 4) A CMP apparatus comprising: a carrier configured to hold a substrate as an object to be polished and to press the substrate against a polishing pad; a polishing table configured to hold the polishing pad and to rotate the polishing pad; a dresser configured to dress the polishing pad; and the apparatus configured to measure surface properties of a polishing pad according to claim 4. ### Claim 7 (depends on 4) The apparatus configured to measure surface properties of a polishing pad according to claim 4, wherein the optical system further comprises a splitter provided between the first mirror and the light source, the splitter being configured to divide the laser beam emitted from the light source. ### Claim 8 A method of measuring surface properties of a polishing pad, comprising: moving a mirror configured to reflect a laser beam emitted from a light source and apply the reflected laser beam to a surface of a polishing pad at a plurality of incident angles, wherein the plurality of incident angles are different from each other; receiving light reflected by the surface of the polishing pad at a plurality of reflection angles; and performing a Fourier transform is performed on the received light reflected at the plurality of reflection angles to determine surface properties of the polishing pad. ### Claim 9 (depends on 8) The method of measuring surface properties of a polishing pad according to claim 8, wherein the plurality of incident angles of the laser beam are selected from an angular range greater than the Brewster angle for the material of the polishing pad as a measuring object. ### Claim 10 (depends on 8) The method of measuring surface properties of a polishing pad according to claim 8, wherein the plurality of incident angles of the laser beam are selected depending on the material of the polishing pad as a measuring object, dressing conditions for the surface of the polishing pad, and the type of a dresser member configured to dress the polishing pad. ### Claim 11 An apparatus configured to measure surface properties of a polishing pad, comprising: an optical system configured to apply at least two laser beams to a polishing pad at at least two different incident angles; and a processing device configured to determine surface properties of the polishing pad by performing a Fourier transform on light reflected by the polishing pad and received by the optical system; wherein the optical system comprises: a first light source configured to emit a first laser beam; a second light source provided at a second position different from a first position of the first light source and configured to emit a second laser beam; a mirror configured to reflect the first laser beam emitted from the first light source and to apply the first laser beam to the polishing pad at a first incident angle, and configured to reflect the second laser beam emitted from the second light source and to apply the second laser beam to the polishing pad at a second incident angle; and at least two light receivers configured to receive the light reflected by the surface of the polishing pad at a first reflection angle corresponding to the first incident angle and at a second reflection angle corresponding to the second incident angle; wherein the Fourier transform is performed on the received light reflected at the first and second reflection angles to determine the surface properties of the polishing pad by the processing device. ### Claim 12 (depends on 11) The apparatus configured to measure surface properties of a polishing pad according to claim 11, wherein the at least one light receiver comprises a CCD element or a CMOS element. ### Claim 13 An apparatus configured to measure surface properties of a polishing pad, comprising: an optical system configured to apply a laser beam to a polishing pad at at least two different incident angles; and a processing device configured to determine surface properties of the polishing pad by performing a Fourier transform on light reflected by the polishing pad and received by the optical system; wherein the optical system comprises: a light source configured to emit the laser beam; a first optical fiber coupled to the light source and configured to apply the laser beam emitted from the light source to the polishing pad at a first incident angle; and a second optical fiber coupled to the light source and configured to apply the laser beam emitted from the light source to the polishing pad at a second incident angle; and at least two light receivers configured to receive the light reflected by the surface of the polishing pad at a first reflection angle corresponding to the first incident angle and at a second reflection angle corresponding to the second incident angle; wherein the Fourier transform is performed on the received light reflected at the first and second reflection angles to determine the surface properties of the polishing pad by the processing device.