Novel EUV Underlayer Design for Metal Oxide Resist Patterning

Abstract

Metal oxide resist (MOR) patterning is extensively utilized in EUV lithography for the next generation devices. Decrease in device sizes and subsequent shrinkage of critical dimensions (CD) had been unavoidable in advanced nodes, leading to inevitable increase of the aspect ratio and the collapse of desired patterns. Preventing pattern collapse has become critical challenge in EUV lithography with MOR, but it could not be fully addressed by the MOR by itself. The underlayer has been introduced to mitigate undesirable pattern collapse and to allow the resist to serve the role as a mask for pattern transfer. Various approaches to prevent pattern collapse via underlayers have been explored, such as matched surface energy at the resist-underlayer interface, enhanced adhesion to the resist and uniform distribution of the related components via crosslinking density control. In this paper, we have designed novel MOR underlayers incorporating appropriate functional groups into the resin to demonstrate improvement in pattern collapse margin upon the patterning with metal oxide resist.