| 摘要 |
PROBLEM TO BE SOLVED: To make high-accuracy alignment possible even when a polishing process is performed by forming an alignment mark of a material having a sufficiently larger mass and density than a thin film formed on the mark has. SOLUTION: After a tungsten (W) layer 23 is formed on a wafer 11, a resist 25 is applied to the W layer 23 and exposed correspondingly to an alignment mark 24 for electron beam so that the resist 25 may be left at the part of the mark 24. Then the mark 24 is formed by removing the W layer 23 except the part coated with the resist 25 and a gate material layer 26 is deposited on the wafer 11. After the layer 26 is deposited, another resist is applied to the upper surface of the layer 26, and the center of the groove of the mark 24 is detected by detecting reflected electronic signals by scanning the mark 24 with an electron beam. Since the mark 24 is formed of tungsten, the mass and density of the mark 24 are largely different from those of the gate material layer 26, and the reflected electronic signals when the electron beam is projected upon the part of the mark 24 are largely different from those when the electron beam is projected upon the other part. The center of the groove of the mark 24 can be detected accurately. |
