Mitigating stochastics in EUV lithography by directed self-assembly
Lander Verstraete, Hyo Seon Suh, Julie Van Bel, Purnota Hannan Timi, R. Vallat, Philippe Bézard, Jelle Vandereyken, Matteo Beggiato, Amir-Hossein Tamaddon, Christophe Béral, Waikin Li, Mihir Gupta, Roberto Fallica
Abstract
Owing to photon shot noise and inhomogeneous distribution of the molecular components in a chemically amplified resist, resist patterns defined by extreme ultraviolet (EUV) lithography tend to suffer from stochastic variations. These stochastic variations are becoming more severe as critical dimensions continue to scale down, and can thus be expected to be a major challenge for the future use of single exposure EUV lithography. Complementing EUV lithography with directed self-assembly (DSA) of block-copolymers provides an interesting opportunity to mitigate the variability related to EUV stochastics. In this work, the DSA rectification process at imec is described for both line/space (L/S) and hexagonal contact hole (HEXCH) patterns. The benefits that rectification can bring, as well as the challenges for further improvement are being addressed based on the current status of imec’s rectification process.