Abstract
There is a growing awareness that underlayers (UL) are important in EUV lithography (EUVL). In previous lithography generations ULs were required to overcome reflectivity, however that is not a concern in EUVL. Nevertheless, surface interactions are becoming prevalent because the different layers of the stack are becoming thinner. This work focuses on the influence of the spin on carbon (SOC) layer used to print line-space patterns with metal containing resists (MCR). A significant impact of underlayers on the MCR performance in EUVL is demonstrated. There are large effects on the dose to size, resist profile and stochastic nanofailures. The main contributor is the interaction between photoresist and underlayer driven by the density of the SOC UL and, to a lesser extent, other chemical interactions. The key message is that underlayer effects cannot be neglected and should be considered when evaluating the lithographic performance of photoresist materials.
