Resist profile modeling with compact resist model

Resist profile shapes become important for 22nm node and beyond as the process window shrinks. Degraded profile shapes for example may induce etching failures. Rigorous resist simulators can simulate a 3D resist profile accurately but they are not fast enough for correction or verification on a full chip. Compact resist models are fast but have traditionally modeled the resist in two dimensions. They provide no information on the resist loss and sidewall angle. However, they can be extended to predict resist profiles by proper setting of optical parameters and by accounting for vertical effects. Large resist shrinkages in NTD resists can also be included in the compact model. This article shows how a compact resist model in Calibre can be used to predict resist profiles and resist contours at arbitrary heights.