On product overlay metrology challenges in advanced nodes

On product overlay (OPO) challenges are quickly becoming yield limiters for the latest technology nodes, requiring new and innovative metrology solutions. In this paper we will cover current and future overlay trends in logic and memory device processing. We will review new lithography overlay challenges and node-after-node trends in the OPO error budget for advanced logic, DRAM, and 3D NAND devices. The central question of this paper is whether optical overlay metrology can keep up with challenges that include accuracy, intra-field variability, target-to-device offset, and others. After surveying the two dominant technologies in optical overlay metrology (IBO and SCOL®), we will outline innovative solutions that will help to address metrology challenges for the new device nodes.