Surface planarization processes for the fabrication of magnetic heads and semiconductor devices are described herein. In one illustrative example, magnetic structures are formed over a substrate and insulator materials are deposited over and around the magnetic structures. A chemical mechanical polishing (CMP) is performed to remove top portions of the insulator materials and to expose the tops of the magnetic structures, such that the tops of the magnetic and insulator materials form a top surface. Due to the different CMP removal rates of the materials, small surface "steps" are formed along the top surface between the materials. To eliminate or reduce these steps, polymer materials (e.g. polystyrene or PMMA) are formed to selectively bond with the tops of the insulator materials to a sufficient thickness so that a substantially planar top surface is formed with tops of the magnetic materials. This may be done by applying a polymer initiator to selectively bond with the tops of the insulator materials and subsequently performing a polymerization process. Alternatively, the polymer materials may be formed by applying a polymer solution to the structure.