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.