Field of the Invention
The present invention relates to a control device for controlling a synchronous positioning of a multi-body system, a control method controlling a synchronous operation of a multi-body system, a lithographic apparatus and a method for manufacturing a device.
Description of the Related Art
A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In such a case, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g. including part of, one, or several dies) on a substrate (e.g. a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Conventional lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at once, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the “scanning”-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction.
During such synchronous scanning, a relative position between the target portion and the pattern should be in accordance with a desired position or set point, thus ensuring that the pattern is projected on the appropriate position on the substrate. If the pattern is not projected onto the appropriate position on the substrate, a so-called overlay error may occur, which may adversely affect the proper operation of the integrated circuit. Typically, the position of the substrate (comprising the target portion) and the patterning device is controlled by controlling the position of the supports (or stages) to which the substrate and patterning device are mounted. In general, a pair of separate closed loop controllers is applied for both controlling a set point to be followed by the stage provided with the patterning device (or reticle) and a set point to be followed by the stage provided with a substrate.
In such approach, both stages are independently controlled to each follow a particular set point, which set point is configured in such manner that the desired synchronous operation is achieved. In a more advanced control strategy (as e.g. described in U.S. Pat. No. 6,373,072), the control of both stages is coupled. In such coupled control strategy, a position error of the substrate stage (i.e. the stage provided with the substrate) may be used to derive a control signal for controlling a position of the reticle stage (i.e. the stage provided with the reticle), in addition to the reticle stage set point. In U.S. Pat. No. 6,373,072, such approach is referred to as a feedthrough method, whereby a position error of the substrate stage is fed through to the controller of the reticle stage.