Electrical generator or motor structure – Dynamoelectric – Linear
Reexamination Certificate
1999-12-23
2001-08-07
Mullins, Burton S. (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Linear
C310S013000, C310S156030, C310S090500, C310S089000, C250S491100, C414S935000
Reexamination Certificate
active
06271606
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to motors that are magnetically coupled through a chamber. More specifically, the present invention is directed to a motor combination that encloses and positions a stage for an exposure apparatus.
BACKGROUND
Linear motors are used in a variety of electrical devices. For example, linear motors are used in exposure apparatuses for semiconductor processing, other semiconductor processing equipment, elevators, electric razors, machine tools, machines, inspection machines, and disk drives.
Exposure apparatuses are commonly used to transfer images from a reticle onto a semiconductor wafer during semiconductor processing. A typical exposure apparatus includes an illumination source, a reticle stage retaining a reticle, a lens assembly and a wafer stage retaining a semiconductor wafer. The reticle stage and the wafer stage are supported above a ground with an apparatus frame. Typically, one or more linear motors precisely position the wafer stage and one or more linear motors precisely position the reticle stage. The images transferred onto the wafer from the reticle are extremely small. Accordingly, the precise relative positioning of the wafer and the reticle is critical to the manufacturing of high density semiconductor wafers.
A typical, linear motor includes a magnet assembly that generates a magnetic field and a coil assembly that is positioned near the magnet assembly. The coil assembly includes one or more coils which are individually supplied with an electrical current. Electrical current in the coils interacts with the magnetic field of the magnet assembly. This causes one of the assemblies to move relative to the other assembly. The assembly that moves can be secured to one of the stages, while the other assembly is secured to the apparatus frame. With this design, the stage moves in concert with one of the assemblies relative to the apparatus frame.
Unfortunately, reaction forces transferred to the apparatus frame from each linear motor can deflect the apparatus frame and influence the positions of the stages. This reduces the accuracy of the exposure apparatus and degrades the quality of the semiconductor wafer. Thus, it is often desirable to transfer the reaction forces directly to the ground with a separate reaction frame or to a reaction mass.
Additionally, depending upon the illumination source, the performance of exposure apparatus can be enhanced by controlling the environment around one or both stages. One way to control the environment around a stage is to position a chamber around the stage. Subsequently, the desired environment can be created within the chamber around the stage. However, with the chamber, it is difficult to transfer the reaction forces from the linear motor to the ground or to a reaction mass.
In light of the above, it is an object of the present invention to provide a motor combination that encloses and positions a stage for an exposure apparatus. Another object of the present invention is to couple a linear motor through a chamber so that the reaction forces from the motor can be transferred outside the chamber. Yet another object of the present invention is to couple a motor through a chamber without compromising the seal of the chamber. Still another object of the present invention is to provide an exposure apparatus capable of manufacturing high density semiconductor wafers.
SUMMARY
The present invention is directed to a motor combination for encircling and positioning an object that satisfies these needs. The motor combination includes a motor that is used for moving and positioning the object and a chamber that encloses the object. The motor includes a first component and a second component. The chamber includes a wall that is interposed between the first component and the second component of the motor.
With the design provided herein, the motor is magnetically coupled through the wall. Further, the object is enclosed by the chamber and the reaction forces of the motor can be easily transferred to the ground or a reaction mass. As a result thereof, the size of the chamber can be reduced because one of the components of the motor is outside the chamber and bulky seals are not needed to seal around the first motor.
As used herein, the term “non-commutated voice coil motor” shall mean a short stroke electromagnetic actuator in which the current is a function of the required force only and not the relative position between the coil and the magnet.
As used herein, the term “commutated linear motor” shall mean an electromagnetic actuator in which the current is varied as a function of the relative position between the coil and the magnet.
A number of alternate embodiments of the motor are provided herein. In each embodiment, one of the components includes at least one magnet and the other component including at least one conductor. Further, the second component moves on a path back and forth relative to the first component. As provided herein, the second component typically moves relative to the first component. Depending upon the direction of movement and the amount of movement, the motor can be either a non-commutated voice coil motor or a commutated motor.
The chamber is positioned between the first component and the second component of the motor and is sized and shaped to enclose the object and the second component of the motor. With this design, the chamber provides a physical barrier between the environment around the first component and the environment around the second component This allows the second component and the object to be positioned in a controlled environment.
The present invention is also directed to a method for enclosing and positioning an object. The method includes the steps of encircling the object with a chamber and magnetically coupling a motor through the chamber. The present invention is also directed to a method for moving an object, a method for manufacturing a motor combination, a method for manufacturing an exposure apparatus and a method for manufacturing a device (for example, semiconductor device).
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Nigel S. Harris,Modern Vacuum Practice, Publication Page and p. 107, Copyright 1989 and Reprinted in 1997, McGraw-Hill Publishing Company, Great Britain at the University Press, Cambridge.
Broder James P.
Mullins Burton S.
Nikon Corporation
Roeder Steven G.
Rose Jim
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