Apparatus for measuring overlay
An overlay measurement apparatus that can quickly measure an overlay error between layers with a large height difference is provided. The overlay measurement apparatus measures an error between a first overlay mark and a second overlay mark formed in a pair on different layers of a wafer. The overla...
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Format: | Patent |
Sprache: | chi ; eng |
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Zusammenfassung: | An overlay measurement apparatus that can quickly measure an overlay error between layers with a large height difference is provided. The overlay measurement apparatus measures an error between a first overlay mark and a second overlay mark formed in a pair on different layers of a wafer. The overlay measurement apparatus includes an imaging system configured to acquire alignment images of a pair of first and second overlay marks at a plurality of focus positions, and a controller communicatively coupled to the imaging system. The overlay measurement apparatus can rapidly and accurately measure an overlay error between layers with a large height difference. |
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