Abstract: The present invention relates to a film thickness measuring method measuring a film thickness of an element formation layer formed on a substrate and its object is to provide a film thickness measuring method which can measure a residual film thickness of a polishing object film in a polishing process at a high accuracy. In a fabrication method of a thin film magnetic head, alumina is coated over a dummy layer 54 and a bottom shielding layer 16 after forming the dummy layer 54 along with the bottom shielding layer 16 and a planarized layer 24 is formed by polishing the surface thereof using a CMP. Next, after forming a top shielding layer 32 over the bottom shielding layer 16, a planarized layer 38 is form by embedding alumina. A film thickness of an embedded 38 on the dummy layer 54 is measured by a non-contact optical film thickness measuring equipment and a film thickness of the top shielding layer 32 is measured based on the film thickness.

Abstract: This invention relates to a polishing method for polishing a surface of a material to be polished and a fabrication method of a thin film magnetic head having a planarization process for planarizing the surface of the material to be polished by polishing, and an object thereof is to reduce variations of a residual film thickness on the surface of a material to be polished after polishing. An insulating film 14 is formed on an AlTiC substrate 12 and a bottom shielding layer 16 is formed thereover. After forming a coating layer 18 and etching a mask layer 22 as an etching mask, a protruding portion of the coating layer 18 at the bottom of the opening of the mask layer 22 is removed by a desired thickness. Since a protruding portion of the coating layer 18 on the periphery of the opening of the mask layer is suitably undercut, the protruding portion is shaved, thereby obtaining the coating layer 18 which is planarized as a whole.