In order to meet the tightened lithography performance requirement for EUV systems, a good on-product focus control with accurate metrology is essential. In this manuscript we report on a novel metrology solution for the EUV on-product focus measurement using YieldStar. The new metrology has been qualified on the Logic product wafers and when combined with the advanced techniques and algorithm shows a performance that is accurate and precise enough to meet EUV requirements. Furthermore, the new methodology provides the opportunity for on-product focus monitoring and control through different scanner interfaces. Here we present a case in which the Imaging Optimizer using the EUV metrology data shows an improvement of over 20% on the focus uniformity.
On-product overlay requirements are becoming more challenging with every next technology node due to the continued decrease of the device dimensions and process tolerances. Therefore, current and future technology nodes require demanding metrology capabilities such as target designs that are robust towards process variations and high overlay measurement density (e.g. for higher order process corrections) to enable advanced process control solutions. The impact of advanced control solutions based on YieldStar overlay data is being presented in this paper. Multi patterning techniques are applied for critical layers and leading to additional overlay measurement demands. The use of 1D process steps results in the need of overlay measurements relative to more than one layer. Dealing with the increased number of overlay measurements while keeping the high measurement density and metrology accuracy at the same time presents a challenge for high volume manufacturing (HVM). These challenges are addressed by the capability to measure multi-layer targets with the recently introduced YieldStar metrology tool, YS350. On-product overlay results of such multi-layers and standard targets are presented including measurement stability performance.
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