Resistivity Impact from Modulated Line-Edge-Roughness with Self-aligned Double Patterning

Self-aligned double patterning (SADP) provides a viable or favorable patterning solution for sub 10nm node without the intervention of EUV. We show the evolution of resulting modulated line-edge-roughness (LER) of non-mandrels from mandrel-cuts with implemented electrical measurements. As to line width down to 70nm, LER led to a reduced effective resistivity due to increased effective line width from LER [Leunissen et al., J. Vac. Sci. Technol., B 24(4), p. 1859, 2006]. For the first time, we report that metal line resistivity increases with the increased effective line width, when line width is further reduced in deep-sub Cu MFP (~20nm). The increase is accredited to excessive electron surface scattering from modulated LER with SADP. The findings are meaningful for comprehensive SADP-adopted product performance analysis (PPA) and can be used to distinguish electron surface scattering and grain boundary scattering from inline sample (there is by far no viable solution for such separation). As the industry continues to scale down and reaches a node where the solution of EUV + SADP is necessary, the findings would become more noteworthy.