As semiconductor technology nodes keep shrinking, ever-tightening on-product overlay (OPO) budgets coupledwith continuous process development and improvement make it critical to have a robust and accurate metrology setup.Process monitoring and control is becoming increasingly important to achieve high yield production. In recentlyintroduced advanced overlay (OVL) systems, a supercontinuum laser source is applied to facilitate the collection ofoverlay spectra to increase measurement stability. In this paper, an analysis methodology has been proposed to couplethe measured overlay spectra with overlay simulation to extract exact process information from overlay spectra. Thispaper demonstrates the ability to use overlay spectra to capture and quantify process variation, which in turn can be usedto calibrate the simulation stacks used to create the SCOL® (scatterometry-based overlay) and AIM® overlay metrologytargets, and can be fed into the fab for process monitoring and improvement.
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