A process for planarizing a patterned metal structure for a magnetic thin film head includes the steps of applying an encapsulation/planarizing material on a substrate, spinning the substrate in a photoresist spinner or similar machine, curing the encapsulation/planarizing layer by energetic particles such as an electron beam. The planarizing process further comprises the step of polishing the entire structure using a conventional chemical-mechanical polishing step. The curing step takes place at the substrate temperature less than 200 C., which prevents the damages of the thin film head structures such as MR and GMR sensors. This process is cheap, efficient and easy to apply.