| CPC G05B 19/4155 (2013.01) [G01B 11/272 (2013.01); G06T 7/0004 (2013.01); G05B 2219/45031 (2013.01); G06T 2207/30148 (2013.01)] | 12 Claims |
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7. An optical system, comprising:
a device comprising:
a first patterned layer having a first pattern;
a second patterned layer above the first patterned layer, the second patterned layer having a second pattern; and
a first passivation film covering the first patterned layer;
a light source that emits light to and reflected by the device; and
an overlay measuring apparatus for determining relative position of first and second patterned layers, the overlay measuring apparatus comprising:
a stage where the device is placed; and
an imaging assembly, comprising:
a plurality of optical heads configured to receive the light reflected from the device; and
a plurality of overlay marks assembled on the plurality of optical heads, respectively, each of the plurality of overlay marks having a third pattern,
wherein one of the plurality of optical heads is aligned with the device on the stage,
wherein the light reflected by the device passes through the overlay mark of the one of the plurality of optical heads, and the light received by the one of the optical heads includes optical images of the first pattern, the second pattern and the third pattern, and
wherein the relative position of the first and second patterned layers are determined based on the optical images of the first pattern, the second pattern and the third pattern included the light received by the one of the plurality of optical heads.
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