The Line Roughness Improvement in Self-aligned Multiple Patterning

Abstract

Multi-patterning has been widely used in the semiconductor industry to enable the continued scaling requirement such as Fin, Gate, and critical Metal lines. Either Self-aligned Multiple Patterning (SaMP) or Litho-Etch/Litho-Etch (LELE) shows plasma etch become more dominant for the line edge and width roughness (LER/LWR) than single patterning technology [1]. To mitigate the strict line roughness requirements for advanced technology nodes (14nm and below), we proposed and demonstrated a novel nitrogen-based Inductively Coupled Plasma (ICP) treatment and an argon-based Capacitively Coupled Plasma (CCP) treatment on LER/LWR improvement, separately. Both recipes are optimized with an optimal design experiment (ODE) statistical method. The optimal organic mandrel etch recipe can improve the LER of the final pattern to 1.2nm. Furthermore, two effective Si mandrel post etch treatment (PET) methods are investigated: special surface plasma treatment and H2 anneal. The H2 anneal effect was found related to the capping layer, different from former published paper. We also found out the different chemistry in Spacer etch can impact line roughness but trade-off with defect performance. Finally, we achieved a 20% LWR improvement of final pattern in a self-aligned quadruple patterning (SAQP) without any side effect.