Photocopying – Projection printing and copying cameras – Step and repeat
Reexamination Certificate
2001-03-02
2003-03-25
Nguyen, Henry Hung (Department: 2851)
Photocopying
Projection printing and copying cameras
Step and repeat
C355S072000, C355S075000
Reexamination Certificate
active
06538719
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an exposure apparatus and exposure method, and a device and its manufacturing method. More particularly, the present invention relates to an exposure apparatus used to manufacture semiconductor devices and liquid crystal display devices and the like in a lithographic process and the exposure method, and a device manufactured by using the exposure apparatus and its manufacturing method using the exposure method to manufacture the device.
BACKGROUND ART
Conventionally, in a lithographic process which is a process when manufacturing a semiconductor device, various exposure apparatus are used to transfer a circuit pattern formed on a mask or a reticle (hereinafter referred to as a “reticle” in general) onto a substrate such as a wafer or a glass plate and the like that are coated with a resist (photoresist).
For example, with the exposure apparatus for semiconductor devices, the reduction projection exposure apparatus that reduces and transfers the pattern formed on a reticle using a projection optical system is mainly used, so as to comply with the finer minimum line width (device rule) of the pattern required with the higher integration of the integrated circuits.
Of the reduction projection exposure apparatus, the static type exposure apparatus (the so-called stepper) which employs the step-and-repeat method to sequentially transfer the pattern formed on the reticle to a plurality of shot areas on the wafer, or an improvement of the stepper which is the scanning exposure apparatus that employs the step-and-scan method (the so-called scanning stepper) disclosed in, for example, Japanese Patent Laid Open No. 08-166043, which synchronously moves the reticle and the wafer in a one dimensional direction and transfers the reticle pattern onto each shot area on the wafer, are well known.
With these reduction projection exposure apparatus, a base plate which is to be the base of the apparatus, is first of all, arranged on the floor. And on the base plate, the main column which supports the reticle stage, the wafer stage, and the projection optical system (projection lens) and the like, is mounted via the vibration isolator which is arranged to isolate the vibration travelling through the floor. With recent reduction projection exposure apparatus, as the vibration isolator, an active vibration isolator is employed. The active vibration isolator comprises an air mount which the internal pressure is adjustable and a voice coil motor, and the vibration of the main column is suppressed by controlling the voice coil motor and the like based on the measurement values of the six accelerometers attached to the main column (mainframe).
With the steppers, after a shot area on the wafer is exposed, exposure is sequentially repeated onto the remaining shot areas. Therefore, the reaction force due to the acceleration and deceleration of the wafer stage (in the case of the stepper) or the reticle stage and the wafer stage (in the case of the scanning stepper) was the cause of vibration of the main column, which in turn caused an unfavorable situation such as creating a positional relationship error between the projection optical system and the wafer.
The error in the positional relationship on alignment and on exposure has consequently been the cause of the pattern being transferred onto a position on the wafer different from the designed value, or in the case the positional error includes a vibration component, led to an image blur (increase in the pattern line width).
Accordingly, in order to prevent the pattern being transferred from shifting, or to suppress the image blur, the vibration of the main column needed to be sufficiently attenuated, such as by the active vibration isolator described above. For example, in the case of the stepper, alignment operation and exposure operation was to begin after the wafer stage was positioned at the desired place and has sufficiently settled down, whereas in the case of the scanning stepper, the reticle stage and the wafer stage had to be sufficiently settled in synchronous before exposure was performed. Consequently, these were causes of lowering the throughput (productivity).
With the size of the wafer increasing in recent years, the size of the wafer stage has also increased, making it difficult to secure the throughput to some extent and performing precise exposure even by using the active vibration isolator earlier described.
To solve such inconvenience, in the Japanese Patent Laid Open No. 02-199813, an exposure apparatus is proposed, which stage holding the substrate and the projection lens mount holding the projection lens are arranged on separate vibration isolation mounts.
However, to arrange the vibration isolation mount on the floor is difficult, due to the features of the vibration isolation mount. Furthermore, since a member which will be the base of the apparatus is necessary, with the exposure apparatus in the Japanese Patent Laid Open No. 02-199813, a main body mount which supports the main body holding the projection lens and a XY stage mount which supports the XY stage are arranged on the same positioning supporting bed. Therefore, even with the exposure apparatus described in the disclosure above, the vibration caused by the reaction force when the XY stage is driven travels via the XY stage mount to the positioning supporting bed, and the vibration further travels via the main body mount to the projection optical system held by the main body. This makes it obvious that the pattern image shift and the image blur and the like, described earlier, cannot be totally prevented.
Since the device rule will become finer in the future, and the wafer and the reticle larger in size, it is evident that the vibration caused when the stage is driven will become a more serious problem. Accordingly, the requirement of a new technology to be developed is pressing, to effectively suppress the adverse effects of the vibration of each component affecting the exposure accuracy.
The present invention has been made in consideration of the situation described above, and has as its first object to provide an exposure apparatus and exposure method which improves both the exposure accuracy and the throughput.
And the present invention has as its second object to provide a highly integrated device on which a fine pattern is accurately formed, and the device manufacturing method.
DISCLOSURE OF INVENTION
According to the first aspect of the present invention, there is provided a first exposure apparatus which forms a predetermined pattern on a substrate (W) by using an exposing optical system (PL), the exposure apparatus comprising: a main column (
14
) which supports the exposing optical system; a first vibration isolator (
56
A to
56
C) which supports the main column; a first base member (BP
1
) which supports the first vibration isolator, mounted on the floor surface (FD); a stage supporting bed (
16
) which supports a substrate stage (WST) which holds the substrate; a second vibration isolator (
66
A to
66
C) which supports the stage supporting bed; and a second base member (BP
2
) which supports the second vibration isolator, mounted on the floor surface independently from the first base member.
According to this aspect, the first vibration isolator supporting the main column is arranged on the first base member, and the second vibration isolator supporting the stage supporting bed is arranged on the second base member which is arranged on the floor surface independently from the first base member. Therefore, vibration travelling between the first base member and the second base member is nearly cut off. So, the reaction force caused with the movement (driving) of the substrate stage supported on the stage supporting bed travels to the second vibration isolator and the second base member, but does not travel to the first base member side. Thus, the reaction force caused with the movement (driving) of the substrate stage is not the cause of vibration of the exposing optical system supported by the main column. Ac
Ito Nobukazu
Takahashi Masato
Nguyen Henry Hung
Nikon Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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