Scaling behavior of wrinkle evolution due to chemical etching of An on stretchable substrate is studied by atomic force microscopy. The surfaces were etched with a small drop of KI solution. Scaling exponent alpha decreased with the etch time, from 0.93 to 0.62. For dynamic exponent beta up to 30 min we find it to be 0.16 +/- 0.05. Within the same time frame, the wavelength increases as similar to t(0.23+-0.05) but drops at 45 min as similar to t(-1.22+-0.42) and saturates. At this stage, we observe percolation island type features along with some wrinkles. The measured value of alpha at this stage is 0.62 +/- 0.02; consistent with the percolation model. The wavelength coarsening at this stage suggests the existence of chemically driven spinodal decomposition. Our obtained value of alpha and beta is consistent with the value of obtained from correlation length which is given by xi=t(1/z). We find z = 4.87 +/- 0.50. Our experiment suggests wrinkle formation in thin films on viscoelastic surface occurs in three stages. (c) 2006 Published by Elsevier B.V.