Manufacturability of computation lithography mask: Current limit and requirements for sub-20nm node

摘要

The computational lithography such as inverse lithography technique (ILT) or source mask optimization (SMO) is considered as the necessary technique for the extremely low kl lithography process of sub-20nm node. The ideal curvilinear mask design for computational lithography gives the impacts and requires many changes on the photomask fabrication from mask data preparation to measurement and inspection. In this paper, we present the current status and new requirements for the computational lithography mask in viewpoint of the manufacturability for mass production. The manufacturability of computational lithography mask can be realized by the predictable and manageable patterning quality. Here, we have proposed new data flow for ILT which covers what the preferred target design is for ILT, new verification method, required mask model accuracy, and resolution improvement method. Furthermore, considering acceptable writing time (＜24 hours) and computation limit on convolution, the current ILT technique is shown to have the limit of application area.