| 摘要 |
An exposure apparatus is equipped with an encoder system which measures positional information of a wafer stage (WST1) by irradiating a measurement beam using four heads (60 1 to 60 4 ) installed on the wafer stage (WST1) on a scale plate (21) which covers the movement range of the wafer stage (WST1) except for the area right under a projection optical system (PL). Placement distances (A, B) of the heads (60 1 to 60 4 ) here are each set to be larger than width (a i , b i ) of the opening of the scale plates (21), respectively. This allows the positional information of the wafer stage to be measured, by switching and using the three heads facing the scale plate out of the four heads according to the position of the wafer stage. |
