Ultrafine lithography pattern inspection using multi-stage TDI image sensors with false image removability
View Patent ↗A workpiece inspection apparatus includes a measured image generator unit configured to measure a pattern of a workpiece and generate a measured image; and a comparator unit configured to compare the measured image to a fiducial image, wherein said measured image generator unit includes a light-receiving device having an interconnection of two or more time delay integration (TDI) sensors each being arranged by two or more line sensors each being arranged by two or more pixels, for generating as the measured image an average value of pixel values excluding an abnormal pixel value from pixels of each TDI sensor with respect to a position of the pattern of the workpiece.
1. A workpiece inspection apparatus comprising:
a measured image generator unit configured to measure a pattern of a workpiece and generate a measured image; and
a comparator unit configured to compare the measured image to a fiducial image, wherein said measured image generator unit includes a light-receiving device having an interconnection of two or more time delay integration (TDI) sensors each being arranged by two or more line sensors each being arranged by two or more pixels, for generating as the measured image an average value of pixel values excluding an abnormal pixel value from pixels of TDI sensors with respect to a position of the pattern of the workpiece,
wherein the light-receiving device has three or more of the TDI sensors, and wherein when calculating as the measured image the average value of pixel values, if an average value difference which is an absolute value of a difference between a pixel value of an i-th TDI sensor and an average value calculated using pixel values of first to (i−1)th TDI sensors is less than or equal to a fiducial value, said measured image generator unit sets as a new pixel value an average value of a pixel value of the i-th TDI sensor and pixel values of the first to (i−1)th TDI sensors, and wherein if the average value difference is not less than the fiducial value then said measured image generator unit performs processing for preventing updating of the average value as the abnormal pixel value and repeats execution of this processing with respect to pixels of all the TDI sensors to thereby obtain an average value and then lets this average value be the measured image.
2. The apparatus according to claim 1 , wherein said measured image generator unit generates as the measured image the average value of pixel values excluding as the abnormal pixel value a pixel value greater than a fiducial value from pixels of each TDI sensor with respect to the position.
3. The apparatus according to claim 1 , wherein said measured image generator unit uses as a fiducial value a sum of an average value of pixel values and a predetermined value and generates as the measured image the average value of pixel values excluding as the abnormal pixel value a pixel value greater than the fiducial value from pixels of each TDI sensor with respect to the position.
4. The apparatus according to claim 1 , wherein the light-receiving device has three or more of the TDI sensors and said measured image generator unit generates as the measured image the average value of pixel values excluding as the abnormal pixel value a pixel value such that an absolute value of a difference between the pixel value and an average value of pixel values of all the three or more TDI sensors at the position is greater than a fiducial value, from pixels of each TDI sensor with respect to the position.
5. A workpiece inspection method comprising:
measuring a pattern of a workpiece using a light-receiving device including an interconnection of two or more time delay integration (TDI) sensors each being arranged by two or more line sensors each being configured from two or more pixels;
generating as a measured image an average value of pixel values excluding an abnormal pixel value from pixels of TDI sensors with respect to a position of the pattern of the workpiece;
and comparing the measured image to a fiducial image to output a compared result,
wherein the light-receiving device has three or more of the TDI sensors, and wherein when calculating as the measured image the average value of pixel values, if an average value difference which is an absolute value of a difference between a pixel value of an i-th TDI sensor and an average value calculated using pixel values of first to (i−1)th TDI sensors is less than or equal to a fiducial value, said generating sets as a new pixel value an average value of a pixel value of the i-th TDI sensor and pixel values of the first to (i−1)th TDI sensors, and wherein if the average value difference is not less than the fiducial value then said generating performs processing for preventing updating of the average value as the abnormal pixel value and repeats execution of this processing with respect to pixels of all the TDI sensors to thereby obtain an average value and then lets this average value be the measured image.