Optics: measuring and testing – By alignment in lateral direction – With light detector
Reexamination Certificate
2000-09-27
2003-09-09
Lee, John R. (Department: 2881)
Optics: measuring and testing
By alignment in lateral direction
With light detector
C378S034000
Reexamination Certificate
active
06618146
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
This invention relates to an oscillation mechanism for producing high-frequency oscillation upon a stage being positioned very precisely. In another aspect, the invention concerns an exposure apparatus having such an oscillation mechanism and/or a device manufacturing method using the same.
In exposure apparatuses, for the manufacture of a very fine pattern such as a circuit pattern of a semiconductor device, further decreases in linewidth of a transferred pattern and further increases of throughput are desired. For a narrowed linewidth of a transferred pattern, the wavelength of exposure light to be used for an exposure process should be shortened more, and the wavelength shortening has been made by using g-line light, i-line light, KrF laser light and so on. As regards synchrotron radiation light emitted from a synchrotron ring, because the wavelength thereof is short, it has an advantage in transferring a very fine pattern and attracts much attention as exposure light in an exposure apparatus.
The synchrotron radiation light emitted from a synchrotron ring comprises a sheet-like beam having a small thickness in a vertical direction. Proposals have been made in relation to it, to oscillatingly move an X-ray mirror for reflecting and directing the sheet-like synchrotron radiation beam to an exposure region, so as to scanningly deflect the beam upon the exposure region thereby to substantively expand the beam irradiation region with respect to the vertical direction.
An example of such an X-ray exposure apparatus is disclosed in Japanese Laid-Open Patent Application, Laid-Open No. 321007/1995.
FIG. 4
shows such an exposure apparatus, wherein denoted at
101
is synchrotron radiation light (hereinafter, “SR beam”) emitted from a synchrotron ring, not shown. Denoted at
102
is an X-ray mirror for reflecting the SR beam
101
, and denoted at
103
is an oscillation mechanism for oscillating the X-ray mirror
102
. Denoted at
104
is a reference stage for holding the X-ray mirror
102
and the oscillation mechanism
103
, and denoted at
105
is an X-ray position detector for detecting the position of the SR beam
101
, wherein the detector
105
is mounted on the reference stage
104
. Denoted at
106
is a mirror chamber for accommodating therein the X-ray mirror
102
, the oscillation mechanism
103
, the reference stage
104
and the like, and the inside space of the mirror chamber is kept at an ultra-high vacuum. Denoted at
107
is a driving mechanism for adjusting the position and posture of the reference stage
104
, and denoted at
108
is a computing unit for processing an output signal of the X-ray position detector
105
to calculate the position of the SR beam
101
. Denoted at
109
is a drive control mechanism for actuating the driving mechanism
107
in response to a signal from the computing unit
108
. Denoted at
110
is a chamber holding unit for securing the mirror chamber
106
on a floor.
In the X-ray exposure apparatus with the structure described above, the position of the SR beam
101
is detected by the X-ray position detector
105
. Then, by using the computing unit
108
, the drive control mechanism
109
and the driving mechanism
107
, the X-ray mirror
102
is positioned with respect to the SR beam
101
. While keeping that position, the X-ray mirror
102
is oscillated by the oscillation mechanism
103
with a predetermined amplitude. With this oscillation of the X-ray mirror
102
, the SR beam of sheet-like shape is scanningly deflected along the exposure region, whereby the beam irradiation region is substantively expanded.
However, the oscillation mechanism such as described above and incorporated into an exposure apparatus involves inconveniences as follows.
If, for example, an oscillation element such as an X-ray mirror is bulky or if the frequency or amplitude of oscillation is large, a large oscillation force is required to produce oscillation of the oscillation element (X-ray mirror) at the predetermined frequency or amplitude. This necessarily cause a large reaction force which is transmitted from the oscillation mechanism to the reference stage for holding the oscillation mechanism. This means a large external disturbance to the reference stage, which causes degradation of the controllability of the reference stage position and thus, degradation of the positioning precision of the SR beam with respect to its positioning reference, for example.
Particularly, in the exposure apparatus as shown in FIG.
4
and in a case where the SR beam
101
is substantively expanded by the X-ray mirror
102
to irradiate the whole mask surface at once (whole surface exposure), if there is an error in shape of the mirror reflection surface or non-uniformness of reflection factor thereof, it directly causes non-uniformness of the intensity of the SR beam projected on the mask surface. In order to average such non-uniformness, it would be necessary to produce high-speed micro-vibration of the X-ray mirror to cause averaging of the SR beam irradiation intensity on the mask surface, as illustrated in FIG.
3
. However, if high-speed micro-vibration of the X-ray mirror
102
is produced, it causes vibration of the reference stage
104
, holding the X-ray mirror
102
and the oscillation mechanism
103
, due to external disturbance. This results in degradation of the positioning precision of the X-ray mirror
102
with respect to the SR beam
101
. Uniform irradiation intensity of the SR beam upon the mask surface is therefore unattainable.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide an oscillation mechanism by which the positioning precision with respect to a certain positioning reference is not degraded even if an oscillation element such as an X-ray mirror is oscillated or vibrated with a predetermined frequency and/or a predetermined amplitude.
It is another object of the present invention to provide an exposure apparatus with such an oscillation mechanism incorporated thereon, by which an X-ray mirror is oscillated or vibrated with a result of uniform SR beam irradiation intensity on a mask surface.
It is a further object of the present invention to provide a device manufacturing method using such an exposure apparatus.
In accordance with an aspect of the present invention, there is provided an oscillation mechanism, comprising: a measuring device for measuring a position of an object; a movable stage being arranged so as to be positioned with respect to the object; a driving mechanism for moving said stage; a control unit for controlling said driving mechanism on the basis of an output of said measuring device; an oscillation element mounted on said stage and being arranged to be oscillated at a predetermined stroke; an intermediate structure having a predetermined mass and being disposed between said stage and said oscillation element; a spring element for coupling said intermediate structure, said stage and said oscillation element with each other; and an oscillating unit for oscillating said oscillation element at a predetermined frequency.
The oscillating unit may be operable to change the oscillating frequency continuously.
The oscillating frequency of said oscillating unit may be changed continuously to determine an oscillating frequency with which vibration to be applied to said stage is minimized.
The oscillating unit may include a piezoelectric device.
In accordance with another aspect of the present invention, there is provided an exposure apparatus, comprising: a light source; a measuring device for measuring a beam from said light source; a movable stage being arranged so as to be positioned with respect to the beam; a driving mechanism for moving said stage; a control unit for controlling said driving mechanism on the basis of an output of said measuring device; an oscillation element mounted on said stage and being arranged to be oscillated at a predetermined stroke, said oscillation element holding an optical element; an intermediate structure having a p
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Lee John R.
Smith II Johnnie L
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