FILM THICKNESS MEASUREMENT METHOD AND FILM THICKNESS MEASUREMENT DEVICE

To provide a film thickness measurement method that substantially widens a wavelength range of reflected light spectrum from a work-piece, and can measure an accurate film thickness.SOLUTION: According to a film thickness measurement method, a work-piece W is pressed against an abrasive pad 2 and is polished while rotating a polishing table 3 which supports the abrasive pad 2, light is guided to the work-piece W from a liquid seal sensor 25 and a transparent window sensor 31 which are located on the polishing table 3 during polishing of the work-piece W, reflected light from the work-piece W is received by the liquid seal sensor 25 and the transparent window sensor 31, and a film thickness of the work-piece W is determined on the basis of reflected light spectrum from the work-piece W.SELECTED DRAWING: Figure 3 【課題】ワークピースからの反射光のスペクトルの波長範囲を実質的に広げ、正確な膜厚を測定することができる膜厚測定方法を提供する。【解決手段】膜厚測定方法は、研磨パッド２を支持する研磨テーブル３を回転させながら、ワークピースＷを研磨パッド２に押し付けてワークピースＷを研磨し、ワークピースＷの研磨中に、研磨テーブル３に配置された液封式センサ２５および透明窓式センサ３１から光をワークピースＷに導き、かつワークピースＷからの反射光を液封式センサ２５および透明窓式センサ３１で受け、ワークピースＷからの反射光のスペクトルに基づいてワークピースＷの膜厚を決定する。【選択図】図３