Certain example embodiments relate to methods of making oxide thin film transistor arrays (e.g., IGZO, amorphous or polycrystalline ZnO, ZnSnO, InZnO, and / or the like), and devices incorporating the same. Blanket layers of an optional barrier layer, semiconductor, gate insulator, and / or gate metal are disposed on a substrate. These and / or other layers may be deposited on a soda lime or borosilicate substrate via low or room temperature sputtering. These layers may be later patterned and / or further processed in making a TFT array according to certain example embodiments. In certain example embodiments, all or substantially all TFT processing may take place at a low temperature, e.g., at or below 150 degrees C., until a post-annealing activation step, and the post-anneal step may take place at a relatively low temperature (e.g., 200-250 degrees C.).