Overlay-shift measurement system

An overlay-shift measurement system, comprising:

• an optical device configured to provide an input light to a metrology target of a semiconductor structure;
• a first light detection device configured to receive a reflected light from the metrology target when the input light illuminates the metrology target;
• and
• a processor configured to determine whether overlay-shift between a plurality of first photonic crystals and a plurality of second photonic crystals in the metrology target is present according to characteristics of the reflected light,
• wherein the first and second photonic crystals have two heights on the semiconductor structure.

An overlay-shift measurement system, comprising:

• an optical device configured to provide an input light to a metrology target of a semiconductor structure;
• a first light detection device configured to receive a transmitted light from the metrology target when the input light penetrates the metrology target;
• a second light detection device configured to receive a reflected light from the metrology target when the input light illuminates the metrology target;
• and
• a processor configured to determine whether overlay-shift between a plurality of first photonic crystals and a plurality of second photonic crystals in the metrology target is present according to characteristics of the transmitted light and the reflected light,
• wherein the first photonic crystals and the second photonic crystals are formed by different materials.