| CPC H01L 21/681 (2013.01) | 9 Claims |

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1. An overlay measurement device for measuring an error between a first overlay mark and a second overlay mark respectively formed on different layers of a wafer, the overlay measurement device comprising:
a light source;
an aperture that changes a beam from the light source to be suitable for photographing the first overlay mark or the second overlay mark;
a detector for obtaining an image of the first overlay mark or an image of the second overlay mark;
a transmission and receipt part; and
a processor connecting to the transmission and receipt part electrically,
wherein the processor is configured to:
obtain data transmitted from a user terminal through the transmission and receipt part,
analyze a recipe included in the data,
perform optimization of measurement options of a wafer, based on the recipe, after the recipe is analyzed,
measure an aperture in a first pinhole position,
measure the aperture in a second pinhole position that is a predetermined distance apart from the first pinhole position once,
calculate Tis 3 Sigma in the first pinhole position and the second pinhole position, and
perform a pinhole optimization process of selecting a pinhole position where the Tis 3 Sigma is a minimum by modeling the Tis 3 Sigma in each pinhole position in relation to the aperture.
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