The surface and interface morphologies and the topographical evolution of an elastic polymethyl methacrylate (PMMA) layer resting on a thin viscous (PS) polystyrene film (thickness ~ 100 nm) were investigated. The PS-PMMA bilayer resting on a silicon wafer was exposed to a selective solvent (cyclohexane) for the PS, thereby reducing the PS glass transition temperature (Tg) below the room temperature and resulting in the viscous behavior of the thin PS film. Topographical evolution of stress-driven micro-patterns both on the surface of the elastic polymer (PMMA) and at the interface of PS-PMMA layers was investigated with increased duration of the exposure top the solvent vapor. Micro-wrinkling of the elastic layer could be controlled spatially owing to the lateral diffusion of the solvent vapors starting from the bilayer edges. Pattern formation with two different characteristic length scales was observed on the elastic, PMMA-air, and viscous-elastic, PS-PMMA, interfaces. Several PMMA/PS bilayer systems with different film thickness were employed to understand the effect of individual film thickness on the spatio-temporal evolution of the micro wrinkling pattern. The proposed technique may have potential applications in meso-patterning of composite polymeric layers where the glass transition temperatures of various polymers are similar and thus thermal annealing may lead to viscous behavior and dewetting of both the layers. Keywords: visco-elastic, diffusion-kinetics, elastic confinement, micro-coarsening, micro- replication.