As leading edge lithography is moving to 2x-nm design rules, lithography control
complements resolution as one of the main drivers and enablers to meet the very
stringent overlay, focus and CD requirements. As part of ASML's holistic
lithography roadmap, ASML is developing several application-specific
optimization and control applications, such as LithoTuner Pattern Matcher and
These applications are all explicitly designed to improve the scanner process
window (overlay, focus, CDU and matching). All these applications have in
common that they require vast amounts of precise, accurate and process robust
wafer data (either taken on product stacks or on so-called monitor wafers).
To provide such essential data in a cost-effective manner, ASML developed a
metrology platform, called YieldStar. This platform is based on an angle-resolved
high-NA scatterometer. It is versatile, as YieldStar's sensor can measure overlay,
CD and focus in a single measurement. Thanks to its high speed, large amounts
of measurements can be quickly collected.
In this paper the latest generation YieldStar is presented, the so-called 200
platform. This YieldStar 200 can be used in a stand-alone configuration (S-200)
or as an integrated module in a lithography track (T-200). First overlay results
show good TMU results without comprising speed. Furthermore, data is shown
that demonstrate YieldStar's capability to reconstruct 3D CD patterns as well.