We plotted the ωG (ω2D) at Step (v) along with each preceding process step to identify the cause of Raman peak variations observed in Step (v) (Figure (c) and (d)). ωG (ω2D) at Step (v) correlated largely with Steps (iii) and (iv) but not with (i) and (ii), indicating that the spatial variations observed in Step (v) became fixed at Step (iii). Graphene on Cu undergoes strain owing to its lattice mismatch and gap in thermal expansion coefficient with the underlying Cu, detaches from the Cu substrate. After etching the Cu layer, the PMMA/graphene films were transferred onto SiO2 substrates, during which a thin water film became trapped at the graphene/SiO2 interface. These entrapped water pockets persistently hinder evaporation and can induce ion sedimentation, leading to inhomogeneous graphene doping. This alters the (ωG, ω2D)