Absolute coordinate system adjustment and calibration by using standalone alignment metrology system

We propose a construction and calibration method of an absolute coordinate system for lithography tools. In the conventional overlay control system, subsequent layers are overlaid on the 1st layer that could have unknown wafer distortion. This is inefficient, because the distortion of the 1st layer may be large. A high-level overlay control can be realized with the absolute coordinate system by correcting the 1st layer to zero distortion. This can be possible by using absolute alignment metrology system. In order to confirm our theory, we report experimental results of the absolute grid construction and matching accuracy among multiple lithography tools.