A method of making a doped silicon oxide thin film using a doped silicon oxide precursor solution includes mixing a silicon source in an organic acid and adding 2-methoxyethyl ether to the silicon source and organic acid to from a preliminary precursor solution. The resultant solution is heated, stirred and filtered. A doping impurity is dissolved in 2-methoxyethanol to from a doped source solution, and the resultant solution mixed with the previously described resultant solution to from a doped silicon oxide precursor solution. A doped silicon oxide thin film if formed on a wafer by spin coating. The thin film and the wafer are baked at progressively increasing temperatures and the thin film and the wafer are annealed.