A method is disclosed for forming a semiconductor tin oxide thin film on a selected region of a surface without forming the film on an adjacent region. An ink film composed of tin(II) carboxylate compound is applied to the surface and heated to partially decompose the compound. A positive photoresist layer is preferably applied to the partially decomposed layer and selectively irradiated to define a mask overlying the selected region. Unwanted photoresist material is dissolved from the adjacent region using an aqueous alkaline solution. It is found that the solution concurrently dissolves the underlying partially decomposed tin compound, without dissolving the compound protected by the mask. Thereafter, the mask is stripped, and the underlying tin compound is heated and further decomposed to produce the desired tin oxide thin film.