Particle analysis of notched wafers
First Claim
1. A method for locating particles on a notched semiconductor wafer, the method comprising:
- (a) scanning a notched semiconductor wafer with a scanning device to obtain scanning device coordinates pertaining to the positions of;
(i) the center of the wafer, (ii) the wafer notch, and (iii) contaminant particles on the wafer;
(b) finding the wafer notch with an imaging device and obtaining its estimated imaging device coordinates;
(c) finding the wafer center with an imaging device and obtaining its estimated imaging device coordinates;
(d) calculating estimated transformation parameters for a coordinate transformation between the coordinate systems of the scanning device and the imaging device based on the scanning device coordinates and the estimated imaging device coordinates of the wafer notch and the wafer center; and
(e) transforming the scanning device coordinates of the particles on the wafer to estimated imaging device coordinates using the estimated transformation parameters.
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Abstract
A method for reducing targeting errors that arise when trying to locate contaminant particles on a notched semiconductor wafer using a high-magnification imaging device, based on estimates of wafer feature positions obtained from a scanning device. The present invention scans a notched semiconductor wafer with a scanning device to obtain scanning device coordinates for the positions of: (i) the wafer center; (ii) the wafer notch; and (iii) contaminant particles on the wafer. Next, the present invention finds the wafer notch and wafer center with an imaging device and obtains their estimated imaging device coordinates. Subsequently, the present invention calculates estimated transformation parameters for a coordinate transformation between the coordinate systems of the scanning device and the imaging device based on the scamping device coordinates and the estimated imaging device coordinates of the wafer notch and the wafer center. Finally, the present invention transforms the scanning device coordinates of the particles on the wafer to estimated imaging device coordinates using the estimated transformation parameters.
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Citations
21 Claims
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1. A method for locating particles on a notched semiconductor wafer, the method comprising:
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(a) scanning a notched semiconductor wafer with a scanning device to obtain scanning device coordinates pertaining to the positions of;
(i) the center of the wafer, (ii) the wafer notch, and (iii) contaminant particles on the wafer;(b) finding the wafer notch with an imaging device and obtaining its estimated imaging device coordinates; (c) finding the wafer center with an imaging device and obtaining its estimated imaging device coordinates; (d) calculating estimated transformation parameters for a coordinate transformation between the coordinate systems of the scanning device and the imaging device based on the scanning device coordinates and the estimated imaging device coordinates of the wafer notch and the wafer center; and (e) transforming the scanning device coordinates of the particles on the wafer to estimated imaging device coordinates using the estimated transformation parameters. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for locating particles on a notched semiconductor wafer, the method comprising:
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(a) scanning a notched semiconductor wafer with a scanning device to obtain scanning device coordinates pertaining to the positions of;
(i) the center of the wafer, (ii) the wafer notch, and (iii) contaminant particles on the wafer;(b) finding the wafer notch with an imaging device and obtaining its estimated imaging device coordinates; (c) finding the wafer center with an imaging device and obtaining its estimated imaging device coordinates; (d) determining an estimated angle of rotation based on the estimated imaging device coordinates of the wafer notch and the wafer center; (e) calculating estimated transformation parameters for a coordinate transformation between the coordinate systems of the scanning device and the imaging device based on the scanning device coordinates and the estimated imaging device coordinates of the wafer notch and the wafer center, and based on the estimated angle of rotation; (f) transforming the scanning device coordinates of the particles on the wafer to estimated imaging device coordinates using the estimated transformation parameters; (g) finding at least two reference particles with an imaging device using their estimated imaging device coordinates and obtaining their actual imaging device coordinates; (h) determining an actual angle of rotation based on scanning device coordinates of the reference particles and the actual imaging device coordinates of the reference particles; (i) determining actual imaging device coordinates of the wafer center based on the scanning device coordinates of the wafer center, the actual imaging device coordinates of the reference particles, and the actual angle of rotation; (j) calculating actual transformation parameters for a coordinate transformation between the coordinate systems of the scanning device and the imaging device based on the actual angle of rotation and using the actual imaging device coordinates of the wafer center; and (k) transforming the scanning device coordinates of the remaining particles on the wafer to imaging device coordinates using the actual transformation parameters. - View Dependent Claims (20)
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21. A method for locating particles on a notched semiconductor wafer, the method comprising:
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(a) scanning a notched semiconductor wafer with a scanning device to obtain scanning device coordinates pertaining to the positions of;
(i) the center of the wafer, (ii) the wafer notch, and (iii) contaminant particles on the wafer;(b) loading the wafer on an image scanning device in a predetermined orientation; (c) finding the wafer notch with an imaging device; (d) obtaining the wafer notch estimated imaging device coordinates by finding the imaging device coordinates of the intersection of two straight lines along the notch perimeter; (e) determining the estimated imaging device coordinates of the wafer center by locating at least three points on the circumference of the wafer and determining the imaging device coordinates of the intersection of perpendicular bisectors of chords drawn between adjacent circumference points; (f) calculating estimated transformation parameters for a coordinate transformation between the coordinate systems of the scanning device and the imaging device based on the scanning device coordinates and the estimated imaging device coordinates of the wafer notch and the wafer center; (g) transforming the scanning device coordinates of the particles on the wafer to estimated imaging device coordinates using the estimated transformation parameters; (h) finding at least two reference particles with an imaging device using their estimated imaging device coordinates and obtaining their actual imaging device coordinates; (i) calculating actual transformation parameters for a coordinate transformation between the coordinate systems of the scanning device and the imaging device based on the scanning device coordinates and the actual imaging device coordinates of the reference particles; and (j) transforming the scanning device coordinates of the remaining particles on the wafer to imaging device coordinates using the actual transformation parameters.
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Specification