Machine element or mechanism – Control lever and linkage systems – Multiple controlling elements for single controlled element
Reexamination Certificate
2002-11-20
2004-05-11
Joyce, William C. (Department: 3682)
Machine element or mechanism
Control lever and linkage systems
Multiple controlling elements for single controlled element
C384S012000, C414S749600, C414S939000
Reexamination Certificate
active
06732610
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a stage mechanism for use in a semiconductor lithography exposure apparatus and, in particular, to a stage mechanism for use in a scan-type exposure apparatus and an EUV exposure apparatus which use an electron beam and operate within a vacuum chamber.
Conventionally, to cope with a semiconductor device whose density has been intensified, there is developed an electron beam drawing apparatus which draws an electron beam directly on a wafer (for example, “Electron Beam Drawing Apparatus”, SEAJ Journal, 24-32, December, 1995). Here,
FIGS. 20 and 21
are respectively longitudinal section views of a stage mechanism employed in a conventional electron beam drawing apparatus. In a guide portion
102
a
of a stage
102
which is disposed in the interior portion of a vacuum chamber
101
in such a manner that it is contacted with the chamber interior portion, conventionally, there is employed a rolling guide system. However, because this rolling guide system is a guide system of a contact type, there are produced minute vibrations when the stage
102
is moved, which has an ill effect on the electron beam drawing operation of the stage mechanism. Also, such movement of the stage
102
causes dust, heat and wear, which results in the degraded accuracy of the electron beam drawing operation. Further, the rolling guide system requires some oil lubrication, that is, oil must be always supplied in order to prevent the environment of the interior of the vacuum chamber from being worsened.
A motor
105
serving as an actuator is disposed at a position distant from a wafer mounting surface
102
b
of the stage
102
, that is, at a position existing outside the vacuum chamber
101
.
The stage
102
can be driven by the motor
105
disposed outside the vacuum chamber
101
through a ball screw
103
, a ball screw receiver
104
, and a rotary shaft
106
connected to the ball screw
103
. In the portion of the vacuum chamber
101
through which the rotary shaft
106
penetrates, there is employed a rotary magnetic seal
107
which uses magnetic fluid so as to keep the vacuum of the interior portion of the vacuum chamber
101
. Therefore, special care must be given to generation of a magnetic field by the rotary magnetic seal
107
.
FIG. 21
shows a conventional electron beam drawing apparatus in which a ball screw is not used but a direct-acting rod
108
is connected to a stage and thus the stage can be driven through the direct-acting rod
108
. By the way, in
FIG. 21
, the stage disposed in the interior portion of the vacuum chamber
101
shown in
FIG. 20
is omitted. Actually, the stage can be driven through the direct-acting rod
108
by a drive stage
109
and a drive motor
105
respectively disposed outside the vacuum chamber
101
. In the portion of the vacuum chamber
101
through which the direct-acting rod
108
penetrates, there is disposed a bellows-like bellows
110
in order to be able to keep the vacuum of the interior portion of the vacuum chamber
101
; however, the bellows
110
must be structured such that it can be expanded and contracted so as to properly follow the movement of the drive stage
109
. Since the expansion and contraction amount of the bellows
110
per one ridge thereof is small, in order to be able to follow the moving amount of the drive stage
109
, it is necessary to use a long bellows-like bellows which has a large number of ridges. For this reason, in the conventional electron beam drawing apparatus shown in
FIG. 21
, there is found a drawback that the moving accuracy of the stage is worsened due to the contracting resistance of the long bellows-like bellows
110
.
In the conventional electron beam drawing apparatus, there are also found other drawbacks that, since a given pattern is drawn on a wafer by scanning an electron beam, the drawing speed is slow and also that, when compared with a stepper system capable of collective transfer using the light, or a step and scan system capable of scanning and exposing a reticle and a wafer synchronously according to the magnification of projection optics, the number of wafers to be processed per hour (that is, throughput) is low.
Thus, to make up for the above-mentioned drawbacks of the electron beam drawing apparatus, there is developed a scan-type exposure apparatus using an electron beam (Lloyd R. Harriot, “Scattering with angular limitation projection electron beam lithography for suboptical lithography”, J. Vac. Sci. Technol. B15, 2130 (1997)).
Recently, the electron beam drawing apparatus is requested that the accuracy of its stage mechanism should be enhanced so as be able to cope with the narrowed width of a drawing line and also that the stage mechanism should be enhanced in speed and acceleration in order to be able to gain the throughput. However, in the stage mechanisms respectively shown in
FIGS. 20 and 21
, due to use of the rolling guide system, the sliding resistance on the guide surface is large which makes it difficult to enhance the accuracy of the stage mechanism; and, enhancement in the speed and acceleration of the stage mechanism increases the wear amount of the stage mechanism to a great extent, which gives rise to the greatly shortened life of the stage mechanism.
Also, while the electron beam drawing apparatus requires a loader which is used to deliver a wafer or a reticle, in the conventional stage mechanisms respectively shown in
FIGS. 20 and 21
, it is difficult to secure a space for installation of the loader. Further, the electron beam drawing apparatus requires an optical length measuring device which is used for positioning control and thus it is also necessary to secure a space for installation of the length measuring device.
SUMMARY OF THE INVENTION
The present invention aims at eliminating the above-mentioned drawbacks found in the conventional stage mechanisms. Accordingly, it is a first object of the invention to provide a stage mechanism for use in a vacuum chamber which employs a non-contact static pressure bearing as a sliding surface thereof to thereby be able not only to increase the speed, acceleration and life of the stage mechanism but also to maintain its high accuracy over a long period of time.
Also, it is a second object of the invention to provide a stage mechanism which, in spite of employment of a non-contact static pressure bearing as a sliding surface thereof, can keep the vacuum environment of the interior portion of the vacuum chamber and thus can maintain a clean environment.
Further, it is a third object of the invention to provide a non-contact slide apparatus for use in a vacuum which can fulfill the requirements for maintaining a drawing accuracy such as non-magnetism, low vibration, and low dust generation, and a stage mechanism for use in such non-contact slide apparatus for use in a vacuum.
Still further, it is a fourth object of the invention to provide a stage mechanism in which a Y slide shaft penetrates through only one side surface of the wall surfaces of a vacuum chamber to thereby allow the remaining wall surfaces to provide free spaces, so that a delivery system such as a wafer loader or a reticle loader can be easily disposed in these free spaces and also there can be easily secured a sufficient space for provision of an optical length measuring device.
In attaining the above objects, according to a first aspect of the invention, there is provided a slide apparatus for use in a vacuum, comprising: two slide shafts disposed so as to penetrate through a vacuum chamber; an X stage base plate connected to the slide shafts within the vacuum chamber; air slide bearings disposed outside the vacuum chamber and in the vicinity of the penetration portions of the slide shafts for guiding their associated slide shafts; bellows respectively for covering the penetration portions of the vacuum chamber for penetration of the slide shafts and the end faces of the air slide bearings opposed to the penetration portions of the vacuum chamber for penetration of the slide shafts to thereby pr
Higuchi Akira
Iwasaki Kenichi
Kato Takayuki
Hansen Colby
Hogan & Hartson
Joyce William C.
Kyocera Corporation
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