1. Field of the Invention
The present invention relates to a stage apparatus including a plurality of stages, a lithography apparatus, and a method of manufacturing an article.
2. Description of the Related Art
In a stage apparatus, the reaction force resulting from the movement of a stage caused by an actuator can adversely affect the stage positioning accuracy through vibration or deformation of the apparatus. The reaction force depends on the product of a mass (moment of inertia) and an acceleration (angular acceleration) of the stage (object to be driven). Therefore, as the (angular) acceleration or the wafer size increases to improve productivity, the reaction force can also increase.
A known technique for reducing the effect of reaction force is to provide a counterweight mechanism or a reaction force cancellation mechanism in a stage apparatus including a plurality of movable stages (Japanese Patent Nos. 3919782 and 4292573).
The stage apparatuses discussed in Japanese Patent Nos. 3919782 and 4292573 include a counterweight mechanism or a reaction force cancellation mechanism, and this often leads to an increase in size of the apparatuses. Furthermore, as the acceleration and the weight of the stage increase, the counterweight mechanism and the reaction force cancellation mechanism can also increase in size. This can increase the amount of heat generated by the counterweight mechanism and the reaction force cancellation mechanism and, furthermore, can also increase the size of a surface plate supporting the stage apparatus and the size of an apparatus including the stage apparatus (increase in footprint). Further, in a case of a reaction force cancellation mechanism in which external force is applied to a surface plate, if the reaction force to be cancelled increases, floor vibration caused by the reaction force cancellation mechanism can also increase.
The present invention is directed to providing, for example, a stage apparatus, including a plurality of movable stages, advantageous in reducing a size thereof.
According to an aspect of the present invention, a stage apparatus includes first, second, third, and fourth stages and a controller. The first, second, third, and fourth stages are arranged along a plane defined by first and second axes orthogonal to each other, each of the first to fourth stages holding an article and being subjected to scanning along the plane. The controller is configured to control the scanning of the first to fourth stages in synchronization such that a pair of the first and second stages and a pair of the third and fourth stages are respectively positioned symmetrically to each other with respect to the first axis and a pair of the first and third stages and a pair of the second and fourth stages are respectively positioned symmetrically to each other with respect to the second axis.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Various exemplary embodiments, features, and aspects of the invention will be described in detail below with reference to the drawings.
Unless otherwise specified, each member or the like is given the same reference numeral throughout the drawings illustrating the exemplary embodiments, and a repetition of description of each member will be omitted.
In the electron beam lithography, a substrate to which a resist has been applied is conveyed to a load lock chamber by the substrate conveyer. To convey the substrate having been exposed to the atmospheric environment into the vacuum chamber under a vacuum environment, the inside of the load lock chamber is vacuum evacuated (exhausted). When the atmospheric pressure in the load lock chamber becomes equal to the atmospheric pressure in the vacuum chamber, the substrate is placed on a stage via a released gate valve. The stage includes a (substrate) chuck for holding a substrate. The chuck can be, but is not limited to, a vacuum chuck, an electrostatic chuck, a water chuck, or the like. The substrate is aligned with respect to the chuck and then held by the chuck. Alternatively, the chuck can be made removable from the stage, and the chuck holding a wafer can be conveyed to the stage. In such a case, the substrate is aligned and then held by the chuck in the chuck chamber, the load lock chamber, or the like, and the substrate and the chuck are conveyed together to the stage by the substrate conveyer. The chuck can be aligned with the stage and then placed on the stage. A method for conveying a substrate to the stage is not limited to that described above, and any other method can also be used.
The single or plurality of stators is supported by the surface plate (supporting member). Thus, when each stage is displaced individually, a reaction force is generated by each stage, which causes the surface plate to vibrate. This vibration can impair the accuracy in stage positioning. Furthermore, if the vibration is transmitted to the electron optical system, the accuracy in electron beam positioning can also be impaired. If each stage individually includes a counterbalancing mechanism or is shared by all stages, the counterbalancing mechanism can cancel reaction forces from the stages to some extent. However, since the mass of and the space for the counterbalancing mechanism are increased, the footprint and the weight of the lithography apparatus 10 can increase. The following describes an arrangement of the lithography apparatus 10 that reduces the foregoing disadvantages.
In the lithography apparatus 10 illustrated in
To cancel the reaction forces of the four stages as described above, the four stages are required to have about the same weight (mass). The weight refers to the weight of the entire moving member and includes the weights of a substrate, a chuck, and the like. Further, when the stages synchronize an operation symmetrically about one of the axes (for example, Y0 axis) as described above, temporal changes in the absolute values of accelerations of the stages in the direction of another axis (for example, X0 axis) need to be about the same (a difference between the absolute values needs to be within a tolerance).
F=ΔaΔm
where m represents the mass of each stage.
The foregoing formula is applicable to cases in which there is no difference in weight between two stages. The following formula takes into consideration a difference in weight between the stages stg1 and stg2:
F=F1−F2=(m1×a1)−(m2×a2)
where F1 represents the reaction force of the stage stg1,
F2 represents the reaction force of the stage stg2,
m1 represents the weight of the stage stg1,
m2 represents the weight of the stage stg2,
a1 represents the acceleration of the stage stg1, and
a2 represents the acceleration of the stage stg2.
If such a reaction force leakage occurs, the force F is applied to the stator 4. This can cause vibration and deformation of the stator 4, the surface plate, other supporting members, floor, and the like. This can result in an error in positioning of each stage. For example, vibration transmitted from the stator 4 can cause an error in positioning of another stage. Further, if vibration transmitted to the surface plate, the floor, or the like is transmitted to other components such as the electron optical systems, the position measurement unit for the measurement of the position of the stages, or the detection unit for the alignment measurement, the performance of pattern formation (resolution performance, overlap precision, or throughput) can be impaired.
Hence, to reduce the amount of reaction force leakage described above, it is necessary to equalize the masses of the four stages as much as possible (differences between the masses are within a tolerance) and to increase the synchronization accuracy of the four stages as high as possible. To increase the synchronization accuracy, it is desirable to increase the natural frequency of the structure of the stage apparatus to increase the control responsiveness (following property) of the stages. Another effective structure is a structure that prevents a leaked reaction force applied to the stator 4 from transmitting to other components (unit). For example, it is effective to make arrangement such that a mechanism (vibration control base such as an air mount) for isolation of vibration between a surface plate or the like (structure) supporting the stator 4 and other units or structures, supports the stator 4 or other components. Use of the foregoing arrangements can reduce the effect of reaction force leakage. It is, however, impossible to reduce the effect of reaction force leakage or reaction force to zero. Hence, when the stages or other components vibrate due to reaction force leakage, it is common to set a settling time (waiting time) before initiation of the measurement or the pattern formation until the position of each stage becomes stable. The structure according to the present exemplary embodiment is advantageous in that it can reduce the reaction force leakage to decrease the settling time that affects the throughput.
While the lithography apparatus 10 illustrated in
The structure of the electron optical system is not particularly limited. For example, a plurality of electron optical systems (multicolumn) can perform processing in parallel on a single substrate, or a single electron optical system (single column) can process a substrate with a plurality of electron beams. As to the lithography apparatus, while the foregoing describes the electron beam lithography apparatus as an example, the lithography apparatus is not limited to the electron beam lithography apparatus. A lithography apparatus that forms a pattern under an atmospheric environment or in an atmosphere of a specific gas can also be used. The stage apparatus according to the present exemplary embodiment is applicable to any apparatus other than lithography apparatuses that includes the stage apparatus such as various types of measurement apparatuses and processing apparatuses.
As the foregoing describes, the present exemplary embodiment can provide a stage apparatus that reduces the effect of reaction forces of a plurality of stages. Hence, the present exemplary embodiment can provide a lithography apparatus that is advantageous in at least one of resolution performance, overlap precision, and throughput.
The substrates W1, W2, W3, and W4 are respectively conveyed by the conveyers 12a, 12b, 12c, and 12d to the stages 21a, 21b, 21c, and 21d in parallel. Then, the stages 21a to 21d synchronize an operation (displacement) to first measure the alignment and then form the pattern on the respective substrates. The synchronous operations are similar to those in the first exemplary embodiment. While the above substrates are conveyed, the stages 21e to 21h synchronize an operation to measure the alignment and form the pattern. After the conveyance is finished, the substrates are respectively removed from the stages 21e to 21h by the conveyers 12e to 12h. The foregoing operations are desirably similar to those illustrated in
While the number of pairs of the stages and the detection units is eight in the present exemplary embodiment, the number of pairs is not limited to eight and can be any multiple of four. If the number of stages that synchronizes an operation is a multiple of four, the number of stages provided does not necessarily have to be a multiple of four. For example, if six stages are provided, four stages among the six stages can synchronize an operation while the remaining two stages can be in a stopped state or an operation in which the reaction forces generated by the two stages do not affect the other processing.
The present exemplary embodiment describes both cases in which the same pattern “F” is formed on the four substrates and in which different patterns are formed on the four substrates. In the case in which the same pattern “F” is formed on the four substrates, since the drawing data is the same, the amount of data transfer is ¼ compared with the cases in which different patterns are formed on the four substrates. Thus, the load of data transfer can be reduced significantly. In the pattern formation, each stage can perform the operation (displacement) according to the position of electron beam irradiation on the substrate by the electron optical system, the position of the substrate on the stage, and the drawing procedure.
The present exemplary embodiment employs the following drawing procedure. First, a stripe area extending in the X-direction on the substrate is drawn through one continuous scanning by the stage. Then, the stage is one step moved in the Y-direction without drawing by a width that is about the same as the width of the stripe area. Thereafter, another stripe area extending in the X-direction on the substrate is drawn through one continuous scanning by the stage. The foregoing procedure is repeated. The distance of the stepping movement is desirably a longest distance possible to an extent that the pattern connection accuracy is satisfied so that the distance is not disadvantageous in terms of throughput. Furthermore, the distance is desirably determined also based on distribution of the amount of correction between the drawing pattern correction by deflection of the electron beams and the drawing pattern correction by correction of pattern data, etc. If an overlap error between the stripe areas connected (overlapped) together in the Y-direction increases, a drawing pattern can be defective. Hence, an adequately high overlap precision is required.
The following describes an example of the drawing procedure on the substrate 1a in
According to the foregoing exemplary embodiment, the controller 5 only needs to prepare (generate) two types of pattern data that are opposite to each other in the data sequence in the X-direction. Simply by doing this, the same pattern can be formed on the four substrates while the stages are synchronously displaced (scanning), enabling highly-precise pattern formation with a reduced effect of reaction forces of the stages.
The foregoing procedure is a mere example, and the procedure is not limited to the foregoing procedure. Examples of other possible procedures include a procedure in which the pattern is formed only when the stages are scanning in one direction in the X-direction and a procedure in which the pattern formation and the stepping movement are repeated for each shot area.
A case is described where different patterns are respectively formed on four substrates. In this case, the stages can be displaced synchronously by the same scanning and stepping procedure to form the pattern regardless of each shot layout. When the pattern is formed by the same procedure, there may be a substrate that has an area on which no pattern formation is necessary, e.g., a part of a shot includes a blank pattern. In this case, it is still important to perform a dummy operation to continuously synchronize the operations of the stages. Further, all the stages can synchronize the operation by a drawing procedure designed for the substrate required to be drawn with the highest accuracy among the four substrates. Further, in a case in which the pattern is formed only on three or fewer substrates, if a stage that does not form the pattern synchronizes an operation (dummy operation) with the other stages that form the pattern, the effect of reaction forces of the stages can be reduced.
As the foregoing describes, the structure according to the present exemplary embodiment can reduce the effect of reaction forces of the stages in both cases in which the same pattern is formed on the four substrates and in which different patterns are formed on the respective four substrates. Thus, the structure according to the present exemplary embodiment is advantageous in at least one of resolving power, overlapping performance, and throughput.
A method of manufacturing an article according to an exemplary embodiment of the present invention is suitable for manufacturing an article such as a micro device, e.g., semiconductor device, and a device having a fine structure. The method of manufacturing an article according to the present exemplary embodiment includes forming a latent image pattern by use of a lithography apparatus on a photosensitive material applied to a substrate (forming a pattern on a substrate) and developing the substrate on which the latent image pattern is formed (developing the substrate on which the pattern is formed). The manufacturing method may further include other conventional treatments (oxidation, film forming, deposition, doping, planarization, etching, resist separation, dicing, bonding, packaging, etc.). The method of manufacturing an article according to the present exemplary embodiment is advantageous in at least one of performance, quality, productivity, and production cost of the article, compared with conventional methods.
Embodiments of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions recorded on a storage medium (e.g., non-transitory computer-readable storage medium) to perform the functions of one or more of the above-described embodiment(s) of the present invention, and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more of a central processing unit (CPU), micro processing unit (MPU), or other circuitry, and may include a network of separate computers or separate computer processors. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2013-096011 filed Apr. 30, 2013, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
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2013-096011 | Apr 2013 | JP | national |