Lithographic apparatus, device manufacturing method and displacement measurement system

摘要

A lithographic apparatus including a moveable object (WT) and a displacement measuring system arranged to determine a position quantity of the moveable object. The displacement measuring system includes an encoder (BC) and a grid structure. One of the encoder and the grid structure is connected to the moveable object. The grid structure includes a high precision grid portion (HG) and a low precision grid portion (LG). The encoder is arranged to cooperate with the high precision grid portion to determine the position quantity relative to the grid structure with a high precision. The encoder is arranged to cooperate with the low precision grid portion to determine the position quantity relative to the grid structure with a low precision.

主权项

1. A lithographic apparatus comprising:
a support structure constructed to support a patterning device, the patterning device being capable of imparting a radiation beam with a pattern to form a patterned radiation beam; a substrate table constructed to hold a substrate; a projection system configured to project the patterned radiation beam onto a target portion of the substrate; and a displacement measuring system arranged to determine a position quantity of a moveable object, wherein the moveable object comprises one of the support structure and the substrate table, wherein the displacement measuring system comprises an encoder and a grid structure, wherein one of the encoder and the grid structure is connected to the moveable object, wherein the grid structure comprises a high precision grid portion and a low precision grid portion, wherein the encoder is arranged to cooperate with the high precision grid portion to determine the position quantity relative to the grid structure with a high precision, wherein the encoder is arranged to cooperate with the low precision grid portion to determine the position quantity relative to the grid structure with a low precision, and wherein the high precision grid portion is provided closer to the projection system than the low precision grid portion.