The Line Roughness Improvement in Self-Aligned Multiple Patterning

Abstract

Multi-patterning has been widely adopted in the semiconductor manufacturing 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 becomes more dominant for the line roughness than single patterning technology (1). To mitigate the strict line roughness requirements for advanced technology nodes, we demonstrated a novel nitrogen-based inductively coupled plasma (ICP) treatment. The recipe was optimized with an optimal design experiment (ODE). The optimal mandrel etch recipe coupled with HBr plasma curing can improve 60% line edge roughness (LER) of the final pattern. Furthermore, two post etch treatment (PET) methods were investigated on Si mandrel: special argon-based plasma treatment and hydrogen annealing. The hydrogen annealing effect was found related to the capping layer, different from previously published paper. Finally, we achieved a 20% line width roughness (LWR) improvement of final pattern in a self-aligned quadruple patterning (SaQP) without any side effect.