Measuring SADP features of the 22nm technology node with old generation CD SEMs

With traditional photolithography technique reaching its limit at around 40nm half pitch, Applied Materials' SADP (Self Aligned Double Patterning) scheme has emerged as a new approach for the 32/22nm technology node. One of the biggest challenges to the SADP program development is the CD (Critical Dimension) measurement capability and control with our current Applied Material's VeritySEM1 (which is designed for the 45nm technology node and up). To meet the more aggressive CD and true LER (Line Edge Roughness) measurement requirements of the SADP features at ∼20nm, we have successfully developed a series of new measurement recipes to measure CDs at different process steps (litho DICD, APF1, APF2, HMO, and STI FICD), including a robust algorithm capable of measuring the ∼20nm SADP features, LER and identifying the look-alike core and gap spaces.