Simulation was done for an advanced memory stack for optimal overlay target design which provides robustness for the process variation and sufficient signal for the stack. Robustness factor and sufficient signal factor sometimes contradicting each other, therefore there is trade-off between these two factors. Simulation helped to find the design to meet the requirement of both factors. The investigation involves also recipe optimization which decides the measurement conditions like wavelength. KLA-Tencor also introduced a new index which help to find an accurate measurement condition. In this investigation, we used CD-SEM to measure the overlay of device pattern after etch or decap process to check the correlation between the overlay of overlay mark and the overlay of device pattern. |
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CITATIONS
Cited by 1 scholarly publication.
Overlay metrology
Metrology
Quality measurement
Signal processing
Image quality
Lithography
Semiconducting wafers