An exposure apparatus has a projection optical system for projecting a pattern of a reticle onto a wafer, a wafer stage to hold and to move the wafer, and a position detecting system to detect a position of the wafer in an optical-axis direction. In accordance with the invention, a contact force is applied to the peripheral side of at least one of the two wafers in order to initiate a bonding wave between the two wafers. The surface of the printed CNT film is slowly eroded away by the particles from the particle gun.