The purpose of this study was to develop a microelectromechanical systems compatible process (e.g., etching, lithography, sputtering) for a polyimide (PI) substrate. A thin-film transistor (TFT) array on the flexible substrate was demonstrated by fully etching aluminum (Al), indium gallium zinc oxide (IGZO), and aluminum oxide (Al2O3). Moreover, during the sputtering process, the surface roughnesses of the IGZO, Al2O3, and Al on the PI substrate were well controlled to as low as 0.457, 0.326, and 12.3 nm, respectively. The devices can be arbitrarily curled on the substrate; therefore, the results are expected to facilitate the development of flexible electronic applications with high bending characteristics.