# US 8,786,850 B2 · Illumination energy management in surface inspection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,786,850 B2 - Document ID: US8786850B2 - Status: Granted - Kind: B2 - Application number: 13/662,626 - Filed: 2012-10-29 - Published: 2014-05-01 - Granted: 2014-07-22 - Earliest claimed: 2012-10-29 - Assignees: KLA-Tencor Corporation - Applicants: KLA-Tencor Corporation - Inventors: Christian Wolters; Aleksey Petrenko; Kurt L. Haller; Juergen Reich; Zhiwei Xu; Stephen Biellak; George Kren - Web page: https://patentgrep.com/patent/US8786850B2 ## CPC - G01N 21/8806: {Specially adapted optical and illumination features} - F21V 23/003: {the elements being electronics drivers or controllers for operating the light source, e.g. for a LED array} - G01N 21/9501: {Semiconductor wafers (manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20)} - G01N 2021/8835: {Adjustable illumination, e.g. software adjustable screen} - 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) - F21V: FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR ## Abstract The disclosure is directed to a system and method of managing illumination energy applied to illuminated portions of a scanned wafer to mitigate illumination-induced damage without unnecessarily compromising SNR of an inspection system. The wafer may be rotated at a selected spin frequency for scanning wafer defects utilizing the inspection system. Illumination energy may be varied over at least one scanned region of the wafer as a function of radial distance of an illuminated portion from the center of the wafer and the selected spin frequency of the wafer. Illumination energy may be further applied constantly over one or more scanned regions of the wafer beyond a selected distance from the center of the wafer. ## Claims ### Claim 1 A system for managing illumination energy applied to a surface of a wafer, comprising: a sample stage configured to receive a wafer; a motor mechanically coupled to the sample stage, the motor configured to actuate the sample stage to rotate the wafer at a selected spin frequency; and an illumination system configured to: illuminate a first portion of the wafer with illumination having a first energy level, wherein the first portion of the wafer is less than a selected radial distance from the center of the wafer, wherein the first energy level is at least partially based upon the selected spin frequency and at least partially based upon a radial distance of the first portion of the wafer from the center of the wafer; illuminate a second portion of the wafer with illumination having a second energy level, wherein the second portion of the wafer is less than the selected radial distance from the center of the wafer, wherein the second energy level is at least partially based upon the selected spin frequency and at least partially based upon a radial distance of the second portion of the wafer from the center of the wafer; and illuminate a third portion of the wafer with illumination having a third energy level, wherein the third portion of the wafer is greater than the selected radial distance from the center of the wafer. ### Claim 2 (depends on 1) The system of claim 1, wherein at least one of the first energy level or the second energy level is proportional to the radial distance of the illuminated portion of the wafer and the selected spin frequency. ### Claim 3 (depends on 1) The system of claim 1, wherein the illumination system includes at least one energy controller configured to attenuate an energy level of illumination delivered to the illuminated portion of the wafer by a selected attenuation, wherein the at least one energy controller includes at least one of an opto-mechanical device, an electrical device, or an electro-optical device. ### Claim 4 (depends on 3) The system of claim 3, wherein the at least one energy controller includes a Pockets cell. ### Claim 5 (depends on 3) The system of claim 3, wherein the illumination system further includes at least one optical element configured to attenuate the energy level of illumination delivered to the illuminated portion of the wafer by a fixed attenuation. ### Claim 6 (depends on 1) The system of claim 1, wherein the illumination system includes at least one focusing element configured to control spot size of illumination delivered to the illuminated portion of the wafer, wherein spot size is associated with energy level of illumination delivered to the illuminated portion of the wafer. ### Claim 7 (depends on 6) The system of claim 6, wherein the at least one focusing element includes at least one refractive element. ### Claim 8 (depends on 7) The system of claim 7, wherein the at least one refractive element includes at least one of: a radially symmetric lens, a cylindrical lens, an astigmatic lens, an anamorphic prism pair, or a multi-element lens assembly. ### Claim 9 (depends on 6) The system of claim 6, wherein the at least one focusing element includes at least one zoom lens assembly. ### Claim 10 (depends on 1) The system of claim 1, wherein the illumination system includes: a waveplate; a polarization element; and at least one motor mechanically coupled to at least one of the waveplate or the polarization element, the at least one motor configured to rotate at least one of the waveplate or the polarization element to control an energy level of illumination directed through the waveplate and the polarization element to the illuminated portion of the wafer. ### Claim 11 (depends on 1) The system of claim 1, wherein the system further includes: an actuation arm mechanically coupled to the sample stage, the actuation arm configured to actuate the sample stage relative to the illumination system to control focus level of illumination delivered to the illuminated portion of the wafer, wherein focus level is associated with an energy level of illumination delivered to the illuminated portion of the wafer. ### Claim 12 (depends on 1) The system of claim 1, wherein the system further includes: an actuation arm mechanically coupled to the sample stage, the actuation arm configured to actuate the sample stage relative to the illumination system to control scan pitch of illumination delivered to the illuminated portion of the wafer, wherein scan pitch is associated with an energy level of illumination delivered to the illuminated portion of the wafer. ### Claim 13 A method of managing illumination energy applied to a surface of a wafer, comprising: receiving a wafer; rotating the wafer at a selected spin frequency; illuminating a first portion of the wafer with illumination having a first energy level, wherein the first energy level is at least partially based upon the selected spin frequency and at least partially based upon a radial distance of the first portion of the wafer from the center of the wafer; and illuminating a second portion of the wafer with illumination having a second energy level, wherein the second energy level is at least partially based upon the selected spin frequency and at least partially based upon a radial distance of the second portion of the wafer from the center of the wafer. ### Claim 14 (depends on 13) The method of claim 13, wherein at least one of the first energy level or the second energy level is proportional to the radial distance of the illuminated portion of the wafer and the selected spin frequency. ### Claim 15 (depends on 13) The method of claim 13, wherein the method further includes: attenuating an energy level of illumination delivered to the illuminated portion of the wafer by a selected attenuation. ### Claim 16 (depends on 15) The method of claim 15, wherein the method further includes: attenuating the energy level of illumination delivered to the illuminated portion of the wafer by a fixed attenuation. ### Claim 17 (depends on 13) The method of claim 13, wherein the method further includes: controlling spot size of illumination delivered to the illuminated portion of the wafer, wherein spot size is associated with energy level of illumination delivered to the illuminated portion of the wafer. ### Claim 18 (depends on 13) The method of claim 13, wherein the method further includes: directing illumination through a waveplate and a polarization element to the illuminated portion of the wafer; and rotating at least one of the waveplate or the polarization element to control an energy level of illumination delivered to the illuminated portion of the wafer. ### Claim 19 (depends on 13) The method of claim 13, wherein the method further includes: disposing the wafer on a sample stage; and actuating the sample stage relative to an illumination system to control focus level of illumination delivered from the illumination system to the illuminated portion of the wafer, wherein focus level is associated with an energy level of illumination delivered to the illuminated portion of the wafer. ### Claim 20 (depends on 13) The method of claim 13, wherein the method further includes: disposing the wafer on a sample stage; and actuating the sample stage relative to an illumination system to control scan pitch of illumination delivered from the illumination system to the illuminated portion of the wafer, wherein scan pitch is associated with an energy level of illumination delivered to the illuminated portion of the wafer. ### Claim 21 A method of managing illumination energy applied to a surface of a wafer, comprising: receiving a wafer; rotating the wafer at a selected spin frequency; illuminating a first portion of the wafer with illumination having a first energy level determined utilizing a first radial distance of the first portion of the wafer from the center of the wafer and the selected spin frequency, wherein the first portion of the wafer is less than a selected radial distance from the center of the wafer; illuminating a second portion of the wafer with illumination having a second energy level determined utilizing a second radial distance of the second portion of the wafer from the center of the wafer and the selected spin frequency, wherein the second portion of the wafer is less than the selected radial distance from the center of the wafer; and illuminating a third portion of the wafer with illumination having a third energy level, wherein the third portion of the wafer is greater than the selected radial distance from the center of the wafer. ### Claim 22 (depends on 21) The method of claim 21, wherein at least one of the first energy level or the second energy level is proportional to a radial distance of an illuminated portion of the wafer from the center of the wafer and the selected spin frequency. ### Claim 23 (depends on 21) The method of claim 21, wherein the method further includes: attenuating an energy level of illumination delivered to an illuminated portion of the wafer by a selected attenuation. ### Claim 24 (depends on 23) The method of claim 23, wherein the method further includes: attenuating the energy level of illumination delivered to the illuminated portion of the wafer by a fixed attenuation. ### Claim 25 (depends on 21) The method of claim 21, wherein the method further includes: controlling spot size of illumination delivered to an illuminated portion of the wafer, wherein spot size is associated with energy level of illumination delivered to the illuminated portion of the wafer. ### Claim 26 (depends on 21) The method of claim 21, wherein the method further includes: directing illumination through a waveplate and a polarization element to an illuminated portion of the wafer; and rotating at least one of the waveplate or the polarization element to control an energy level of illumination delivered to the illuminated portion of the wafer. ### Claim 27 (depends on 21) The method of claim 21, wherein the method further includes: disposing the wafer on a sample stage; and actuating the sample stage relative to an illumination system to control focus level of illumination delivered from the illumination system to an illuminated portion of the wafer, wherein focus level is associated with an energy level of illumination delivered to the illuminated portion of the wafer. ### Claim 28 (depends on 21) The method of claim 21, wherein the method further includes: disposing the wafer on a sample stage; and actuating the sample stage relative to an illumination system to control scan pitch of illumination delivered from the illumination system to an illuminated portion of the wafer, wherein scan pitch is associated with an energy level of illumination delivered to the illuminated portion of the wafer.