Translation Certification
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`I, Friedemann Horn, European patent attorney and patent translator
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`having a good command of both the English and the Japanese language in the
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`relevant technical field, hereby certify that the attached document is, to the best
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`of my knowledge and belief, a true and complete translation from Japanese into
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`English of the content of the PCT patent application published in W099/49504A.
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`Munich, Germany
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`Dated this April 22, 2013
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`‘~fxwW.l4w~
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`Signature of the translator
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`1
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`ZEISS 1015
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`1
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`ZEISS 1015
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`Translation from Japanese into English of W099/49504
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`DESCRIPTION
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`PROJECTION EXPOSURE METHOD AND APPARATUS
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`Technical Field
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`The present invention relates to a projection exposure method and
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`apparatus for use in transferring a mask pattern onto a photosensitive substrate
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`in a lithography process performed to manufacture devices such as, for example,
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`semiconductor devices, imaging devices (CCDs or the like), liquid crystal display
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`devices, or thin film magnetic heads, and more particularly to a projection
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`exposure method and apparatus using a liquid immersion method.
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`Background Art
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`In the manufacture of semiconductor devices or the like, a projection
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`exposure apparatus is used to transfer the image of a pattern on a reticle as a
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`mask to each shot area on a wafer (or a glass plate) coated with a resist as a
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`photosensitive substrate via a projection optical system. Conventionally, step-
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`and-repeat type reduction projection exposure apparatuses (steppers) have been
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`frequently used as projection exposure apparatuses. Recently, however, attention
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`is also being given to step-and-scan type projection exposure apparatuses, which
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`synchronously scan and expose the reticle and the wafer.
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`The resolution of the projection optical system provided in the projection
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`exposure apparatus becomes higher as the exposure wavelength employed
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`decreases and as the numerical aperture of the projection optical system
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`increases. Consequently, with the miniaturization of integrated circuits, the
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`exposure wavelength used in projection exposure apparatuses decreases every
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`year and the numerical aperture of projection optical systems gradually increases.
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`While the currently dominant exposure Wavelength is the 248 nm of a KIF
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`excimer laser, an even shorter wavelength of 193 nm of AIF excimer lasers is also
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`coming into practical use.
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`Furthermore, the depth of focus (DOF) is as important as the resolution
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`when performing an exposure. The resolution R and the depth of focus 8 are
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`expressed by the following equations, respectivelyi
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`(1)
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`1 2
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`R = k1'A/NA
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`Translation from Japanese into English of W099/49504
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`5 = k2'}x /NA2
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`(2)
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`where A is the exposure wavelength, NA is the numerical aperture of the
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`projection optical system, and k1 and k 2 are the process factors. As apparent
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`from the equations (1) and (2), the depth of focus 8 decreases when the exposure
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`wavelength A is reduced and the numerical aperture NA is increased in order to
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`improve the resolution R. Conventionally, projection exposure apparatuses
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`perform exposure with the surface of the wafer aligned with the image plane of
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`the projection optical system by autofocusing, and for this reason, the depth of
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`focus 3 preferably has a certain width. Therefore, methods for substantially
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`increasing the depth of focus that have been conventionally suggested are the
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`phase'shift reticle method, the modified illumination method, and the multilayer
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`resist method.
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`As described above, conventional projection exposure apparatuses tend to
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`have a shorter depth of focus due to a reduction in the wavelength of exposure
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`light and an increase in the numerical aperture of the projection optical system.
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`Moreover, even shorter exposure wavelengths are being studied in order to keep
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`up with the tendency toward higher degrees of integration of semiconductor
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`integrated circuits. Therefore, the depth of focus will be too narrow if things
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`continue as’ they are and it could lead to insufficient margins during exposure.
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`Accordingly, a liquid immersion method has been proposed as a method
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`for substantially shortening the exposure wavelength and increasing the depth of
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`focus. With this liquid immersion method, the space between the lower surface of
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`the projection optical system and the surface of the wafer is filled with liquid
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`such as water or an organic solvent, thus taking advantage of the fact that the
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`wavelength of the exposure light in the liquid is 1/n of the wavelength in air
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`(Where n is the refractive index of the liquid, normally approximately 1.2 to 1.6),
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`thereby improving the resolution as well as magnifying the depth of focus about 11
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`times.
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`If the liquid immersion method is simply applied to the step'and'repeat
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`type projection exposure apparatus, the liquid spills out from the space between
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`the projection optical system and the wafer when stepping the wafer to the next
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`shot area after completion of exposure of one shot area. Therefore, it is necessary
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`to supply the liquid again and it is difficult to recover the liquid. In addition, if
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`the liquid immersion method is temporarily applied to a step-and scan type
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`projection exposure apparatus, the exposure is performed while moving the wafer
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`Translation from Japanese into English of W099/49504
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`and therefore the space between the projection optical system and the wafer
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`needs to be filled with the liquid while moving the wafer.
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`In view of the above viewpoints, it is an object of the present invention to
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`provide a projection exposure method capable of stably keeping the space
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`between a projection optical system and a wafer filled with liquid when applying
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`the immersion method even if the projection optical system and the wafer
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`relatively move. It is another object of the present invention to provide a
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`projection exposure apparatus capable of performing the projection exposure
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`method, a method for efficiently manufacturing the projection exposure
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`apparatus, and a method for manufacturing an advanced device using the
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`projection exposure method.
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`Disclosure of the Invention
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`According to the present invention, in a first projection exposure method
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`for illuminating a mask (R) with an exposure beam and transferring a pattern on
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`the mask (R) onto a substrate (W) via a projection optical system (PL), when the
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`substrate (W) is moved in a predetermined direction, a predetermined liquid (7)
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`is caused to flow in a moving direction of the substrate (W) so as to fill the space
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`between the front end of an optical element (4) on the substrate (W) side of the
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`projection optical system (PL) and the surface of the substrate (W) with the liquid
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`(7).
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`According to the first projection exposure method of the present invention,
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`a liquid immersion method is applied to thereby fill the space between the front
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`end of the projection optical system (PL) and the substrate (W) with the liquid.
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`Therefore, the wavelength of exposure light at the substrate surface can be
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`reduced to 1/n (where n is the refractive index of the liquid) compared to the
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`wavelength in air and the depth of focus is increased to about 11 times of the
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`value obtained in air. Furthermore, when the substrate is moved in the
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`predetermined direction, the liquid is caused to flow in the moving direction of
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`the substrate. Therefore, the space between the front end of the projection optical
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`system and the surface of the substrate is filled with the liquid even while the
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`substrate is moved. Moreover, if foreign matter adheres to the substrate, the
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`foreign matter can be washed away by means of the liquid.
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`Subsequently, according to the present invention, a first projection
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`exposure apparatus for illuminating a mask (R) with an exposure beam and
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`transferring a pattern on the mask (R) onto a substrate (W) via a projection
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`optical system (PL), includes a substrate stage (9, 10), which holds and moves the
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`substrate (W); a liquid supply device (5) which supplies a predetermined liquid
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`(7) in a predetermined direction via a supply pipe (21a) so as to fill the space
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`between the front end of an optical element (4) on the substrate (W) side of the
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`projection optical system (PL) and the surface of the substrate (W); and a liquid
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`recovery device (6), which recovers the liquid (7) from the surface of the substrate
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`(W) via a discharge pipe (23a, 23b) disposed together with the supply pipe (21a)
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`in such a way that an area irradiated with the exposure beam is arranged
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`between the discharge pipe and the supply pipe in the predetermined direction,
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`wherein the liquid (7) is supplied and recovered while the substrate (W) is moved
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`in the predetermined direction by driving the substrate stage (9, 10).
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`According to the first projection exposure apparatus of the present
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`invention, the first projection exposure method of the present invention can be
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`performed by using the pipes.
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`It is preferable to provide a second pair of a supply pipe (22a) and a
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`discharge pipe (24a, 24b) in an arrangement obtained by rotating the pair of
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`supply pipe (21a) and discharge pipe (23a, 23b) by substantially 180°. In this case,
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`if the substrate (W) is moved in a direction opposite to the predetermined
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`direction, the space between the front end of the projection optical system (PL)
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`and the surface of the substrate (W) can be continuously filled with the liquid (7)
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`in a stable manner by using the latter pair of pipes.
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`Furthermore, if the projection exposure apparatus is of a scanning
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`exposure type, which synchronously moves and exposes the mask (R) and the
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`substrate (W) with respect to the projection optical system (PL), the
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`predetermined direction is preferably the scanning direction of the substrate (W)
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`during the scanning exposure. In this case, also during the scanning exposure,
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`the space between the front end of the optical element (4) on the substrate (W)
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`side of the projection optical system (PL) and the surface of the substrate (W) can
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`be continuously filled with the liquid (7), whereby the exposure can be performed
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`in a stable manner with high accuracy.
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`Furthermore, it is preferable to provide one pair or two inverted pairs of a
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`supply pipe (27a) and a discharge pipe (29a, 29b) in a direction perpendicular to
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`the predetermined direction in an arrangement corresponding to the pair of the
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`supply pipe (21a) and the discharge pipe (23a, 23b). In this case, also while the
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`substrate (W) is stepped in the direction perpendicular to the predetermined
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`direction, the space between the front end of the projection optical system (PL)
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`and the surface of the substrate (W) can be continuously filled with the liquid (7).
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`Furthermore, the projection exposure apparatus preferably includes a
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`control system (14), which adjusts a supply amount and a recovery amount of the
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`liquid (7) in accordance with a moving velocity of the substrate stage. More
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`specifically, for example, the control system can be used to increase the supply
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`amount when the moving velocity is high and to decrease the supply amount
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`when the moving velocity is low, by which it is possible to effectively keep the
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`space between the front end of the projection optical system (PL) and the surface
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`of the substrate (W) filled constantly with the liquid.
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`Furthermore, the liquid (7) supplied to the surface of the substrate (W) is,
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`for example, pure water or fluorinated inert liquid regulated to a predetermined
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`temperature. In this case, pure water is easily available, for example, in a
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`semiconductor manufacturing factory and it is furthermore unproblematic for the
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`environment. In addition, the liquid (7) is temperature'controlled and therefore
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`the surface of the substrate can also be temperature'controlled, which can
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`prevent a thermal expansion of the substrate (W) caused by heat generated
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`during exposure. Although naturally it is desirable that the liquid has a high
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`transmittance with respect to the exposure beam, the absorbed amount of the
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`exposure beam is extremely low even if the transmittance is low, since the
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`working distance of the projection optical system is short.
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`Subsequently, according to the present invention, a projection exposure
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`apparatus manufacturing method includes the assembly, in a predetermined
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`positional relationship, of an illumination system (1) for irradiating a mask (R)
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`with an exposure beam; a projection optical system (PL) for transferring an
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`image of a pattern on the mask onto a substrate (W); a substrate stage (9, 10) for
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`holding and moving the substrate (W); a liquid supply device (5) for supplying a
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`predetermined liquid (7) in a predetermined direction via a supply pipe (21a) so
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`as to fill the space between the front end of an optical element (4) on the
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`substrate (W) side of the projection optical system (PL) and the surface of the
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`substrate (W); and a liquid recovery device (6) for recovering the liquid (7) from
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`the surface of the substrate (W) via a discharge pipe (23a, 23b) disposed together
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`with the supply pipe (21a) in such a way that the area (4) irradiated with the
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`exposure beam is arranged between the discharge pipe (23a, 23b) and the supply
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`pipe (21a) in the predetermined direction.
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`Furthermore, according to the present invention, a first device
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`manufacturing method using the first projection exposure method of the present
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`invention includes an exposure step of irradiating a mask (R) with an exposure
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`beam and transferring a pattern on the mask (R) onto a substrate (W) for a
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`device via a projection optical system (PL), wherein a predetermined liquid (7) is
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`caused to flow in a moving direction of the substrate (W) so as to fill the space
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`between the front end of an optical element (4) on the substrate (W) side of the
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`projection optical system (PL) and the surface of the substrate (W) when the
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`substrate (W) is moved in a predetermined direction in the exposure step. A
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`liquid immersion method is applied, so that an advanced device can be
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`manufactured.
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`Subsequently, according to the present invention, in a second projection
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`exposure method for irradiating a mask (R) with an exposure beam and exposing
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`a substrate (W) with the exposure beam via a projection optical system (PL),
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`liquid (7) is caused to flow so as to fill the space between the projection optical
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`system and the substrate and the flowing direction of the liquid is changed in
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`accordance with the moving direction of the substrate.
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`According to the second projection exposure method of the present
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`invention, the liquid immersion method is applied to fill the space between the
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`projection optical system (PL) and the substrate (W) with the liquid. Therefore,
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`the wavelength of the exposure light on the substrate surface can be reduced to
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`1/n (where n is the refractive index of the liquid) compared to the wavelength in
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`air and the depth of focus can be increased to about 11 times of the value obtained
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`in air. Furthermore, even if the moving direction of the substrate changes
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`frequently, the space between the projection optical system and the substrate can
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`be continuously filled with the liquid by changing the flowing direction of the
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`liquid according to the moving direction of the substrate.
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`Preferably, when a supply velocity of the liquid (7) is divided into a first
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`component in the moving direction of the substrate and a second component
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`perpendicular to this moving direction, the liquid (7) is caused to flow in such a
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`way that the first component is equal to or less than a predetermined permissible
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`value if the first component is opposite to the moving direction of the substrate
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`(W). This lowers the component of velocity of the liquid opposite to the moving
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`direction of the substrate (W) and therefore the liquid can be smoothly supplied.
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`Furthermore, more preferably the liquid (7) is caused to flow
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`substantially in the moving direction of the substrate (W).
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`If the substrate (W) is exposed by step'and-repeat or by step-and-scan,
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`preferably the liquid (7) is caused to flow substantially along the stepping
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`direction of the substrate (W).
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`Still further, preferably the mask (R) and the substrate (W) are each
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`moved relatively to the exposure beam while scanning and exposing the
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`substrate with the exposure beam, and the liquid (7) is caused to flow
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`substantially along the scanning direction of the substrate during the scanning
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`exposure.
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`Furthermore, preferably the flow rate of the liquid (7) is adjusted
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`according to the moving velocity of the substrate (W).
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`According to the present invention, a second device manufacturing
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`method includes a lithography step which includes a step of transferring a device
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`pattern onto a substrate (W) by using the second projection exposure method of
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`the present invention. The liquid immersion method is applied to the method, by
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`which an advanced device can be manufactured.
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`According to the present invention, a second projection exposure
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`apparatus for illuminating a mask (R) with an exposure beam and performing
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`transfer onto a substrate (W) with the exposure beam via a projection optical
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`system (PL) includes a liquid supply device (5) which lets liquid (7) flow so as to
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`fill the space between the projection optical system and the substrate with the
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`liquid (7) and changes the flowing direction of the liquid according to a moving
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`direction of the substrate.
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`According to the second projection exposure apparatus of the present
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`invention, the second projection exposure method of the present invention can be
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`performed and the space between the projection optical system and the substrate
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`can be filled with the liquid even if the moving direction of the substrate
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`frequently changes.
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`Preferably, the projection exposure apparatus further includes a stage
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`system (RST, 9 to 11) which moves the mask (R) and the substrate (W) relatively
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`to the exposure beam, wherein the liquid supply device (5) causes the liquid (7) to
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`flow substantially in the moving direction of the substrate during the scanning
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`exposure of the substrate.
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`Furthermore, preferably the projection exposure apparatus further
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`includes a liquid recovery device (6) which recovers the liquid (7) supplied
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`between the projection optical system (PL) and the substrate (W).
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`Still further, preferably a supply port (21a) of the liquid supply device (5)
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`and a recovery port (23a, 23b) of the liquid recovery device (6) are disposed in
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`such a way that an area irradiated with the exposure beam is arranged between
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`the supply port and the recovery port.
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`Brief Description of the Drawings
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`Fig. 1 is a diagram showing the schematic configuration of a projection
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`exposure apparatus employed in a first embodiment of the present invention. Fig.
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`2 is a diagram showing the positional relationship between the front end 4A of a
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`lens 4 of a projection optical system PL and discharge nozzles and inflow nozzles
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`for the X-direction. Fig. 3 is a diagram showing the positional relationship
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`between the front end 4A of the lens 4 of the projection optical system PL in Fig.
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`1 and discharge nozzles and inflow nozzles for supplying and recovering liquid in
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`the Y-direction. Fig. 4 is an enlarged diagram of the principal portion showing
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`how the liquid 7 is supplied to or recovered from the space between the lens 4 and
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`a wafer W shown in Fig. 1. Fig. 5 is a front View showing the lower end of the
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`projection optical system PLA, a liquid supply device 5, a liquid recovery device 6,
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`and the like of the projection exposure apparatus employed in a second
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`embodiment of the present invention. Fig. 6 is a diagram showing the positional
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`relationship between the front end 32A of a lens 32 of the projection optical
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`system PLA in Fig. 5 and the discharge nozzles and the inflow nozzles for the X-
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`direction. Fig. 7 is a diagram showing the positional relationship between the
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`front end 32A of the lens 32 of the projection optical system PLA in Fig. 5 and the
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`discharge nozzles and the inflow nozzles for supplying and recovering liquid in
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`the Y'direction.
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`Best Mode for Carrying out the Invention
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`Hereinafter, a preferred embodiment of the present invention will be
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`described with reference to Fig. 1 to Fig. 4. In this embodiment, the present
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`invention is applied to a case where a step-and-repeat type projection exposure
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`apparatus is used to perform exposure.
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`Fig. 1 shows a schematic configuration of the projection exposure
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`apparatus according to this embodiment. In Fig. 1, a pattern formed on a reticle
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`R is irradiated with exposure light IL, which is a UV pulse light having a
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`wavelength of 248 nm emitted from an illumination optical system 1 including a
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`KrF excimer laser light source as an exposure light source, an optical integrator
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`(homogenizer), a field stop, and a condensing lens. The pattern on the reticle R is
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`projected in a reduced scale onto an exposure area on a Wafer W coated with
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`photoresist at a predetermined projection magnification B (B is, for example, 1/4
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`or 1/5) Via the projection optical system PL which is telecentric on both sides (or
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`on the side of the wafer W). The exposure light IL can be an ArF excimer laser
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`beam (with 193 nm wavelength), a F2 laser beam (With 157 nm wavelength), an i'
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`line (with 365 nm wavelength) emitted from a mercury lamp, or the like.
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`Hereinafter, the configuration will be described with the Z'axis set in parallel to
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`the optical axis AX of the projection optical system PL, the Y'axis set
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`perpendicular to the paper surface of Fig. 1 within the plane perpendicular to the
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`Z'axis, and the X'axis set in parallel to the paper surface of Fig. 1.
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`The reticle R is held on a reticle stage RST. The reticle stage RST
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`includes a mechanism for slightly moving the reticle R in the X'direction, Y-
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`direction, and rotative direction. A two-dimensional position and a rotation angle
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`of the reticle stage RST are measured by a laser interferometer (not shown) in
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`real time and a main control system 14 positions the reticle R based on the
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`measured values.
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`On the other hand, the wafer W is fixed on a Z-stage 9 for controlling a
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`focus position (the position in the Z-direction) and a tilt angle of the Wafer W via
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`a wafer holder (not shown). The Z'stage 9 is fixed on an XY-stage 10 which moves
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`along an XY plane substantially parallel to an image plane of the projection
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`optical system PL, with the XY'stage 10 mounted on a base 11. The Z'stage 9
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`controls the focus position (the position in the Z-direction) and the tilt angle to
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`align the surface of the wafer W with the image plane of the projection optical
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`system PL by autofocusing and autoleveling. Furthermore, the XY'stage 10
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`positions the wafer W in the X'direction and the Y'direction. The two-
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`dimensional position and the rotation angle of the Z'stage 9 (Wafer W) are
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`measured as the position of a moving mirror 12 in real time by a laser
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`interferometer 13. Control information is sent from the main control system 14 to
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`a wafer stage drive system 15 based on the measurement result and the wafer
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`stage drive system 15 controls the operations of the Z-stage 9 and the XY-stage
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`10 based on the control information. During exposure, each shot area on the
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`wafer W is stepped sequentially to the exposure position and the operation of
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`exposing a pattern image on the reticle R is repeated in a step'and'repeat
`manner.
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`In this example, the liquid immersion method is used in order to
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`substantially reduce the exposure Wavelength to improve the resolution and to
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`substantially increase the depth of focus. Therefore, at least while the pattern
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`image on the reticle R is being transferred onto the wafer W, the space between
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`the surface of the wafer W and the front end surface (lower surface) of the lens 4
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`on the wafer side of the projection optical system PL is filled with a
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`predetermined liquid 7. The projection optical system PL has a lens barrel 3 for
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`housing other optical systems and a lens 4 of the lens barrel 3, and is configured
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`in such a Way that only the lens 4 comes in contact with the liquid 7. This
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`prevents corrosion or the like of the lens barrel 3, which is made of metal.
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`The projection optical system PL is composed of a plurality of optical
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`elements including the lens 4, with the lens 4 attachably and detachably
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`(exchangeably) fixed to the bottom of the lens barrel 3. While the optical element
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`closest to the wafer W, in other words, in contact with the liquid 7 is a lens in this
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`example, the optical element is not limited to a lens, but can also be an optical
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`plate (plane-parallel plate or the like) used to adjust the optical properties of the
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`projection optical system PL such as, for example, an aberration (spherical
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`aberration, coma aberration, or the like) thereof. In addition, the surface of the
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`optical element coming in contact with the liquid 7 becomes dirty due to the
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`adhesion of scattered particles generated from the resist when it is irradiated
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`with the exposure light or impurities contained in the liquid 7. Therefore, it is
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`necessary to periodically exchange the optical element. When the optical element
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`coming in contact with the liquid 7 is a lens, however, the cost of the exchanged
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`component is high and the time required for the exchange is long, which causes
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`an increase in maintenance cost (running cost) or a decrease in throughput.
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`Therefore, the optical element coming in contact with the liquid 7 can be, for
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`example, a plane'parallel plate which is lower in price than the lens 4. If a plane-
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`parallel plate is used, and a substance (for example, any silicon'based organic
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`matter), which deteriorates the transmittance of the projection optical system PL,
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`the illumination of the exposure light on the wafer W, and the uniformity of the
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`illumination distribution, adheres to the plane-parallel plate during the
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`transport, assembly, adjustment, or the like of the projection exposure apparatus,
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`then it is sufficient to exchange the plane'parallel plate immediately before
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`supplying the liquid 7. Therefore, the advantage is obtained that the exchange
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`costs are lowered in comparison to the case in which a lens is used as the optical
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`element coming in contact with the liquid 7.
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`In addition, for example, pure water is used as the liquid 7 in this
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`example. Pure water is advantageous in that it is easily obtainable in large
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`amounts, for example, in semiconductor manufacturing plants, and that it exerts
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`no harmful influence on the photoresist on the wafer, the optical lens, and the
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`like. Furthermore, pure water exerts no harmful influence on the environment,
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`and its content of impurities is extremely low. Therefore, it can also be expected
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`to have the effect of washing the surface of the wafer and the surface of the lens 4.
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`In addition, the refractive index n of pure water (water) with respect to
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`the exposure light having a wavelength of about 250 nm is substantially 1.4.
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`Therefore, the wavelength of 248 nm of the KrF excimer laser beam is reduced to
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`1/n, i.e., about 177 nm on the wafer W, and thus a high resolution is obtained.
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`Furthermore, the depth of focus is magnified by about 11 times, i.e., about 1.4
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`times the Value obtained in air. Therefore, if it is sufficient to secure a depth of
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`focus that is approximately equivalent to that in air, then the numerical aperture
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`of the projection optical system PL can be further increased. Also in this
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`viewpoint, the resolution is improved.
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`The liquid 7 is supplied in a temperature-controlled condition onto the
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`wafer W via a predetermined discharge nozzle or the like by a liquid supply
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`device 5 composed of a tank of the liquid, a pressure pump, and a temperature
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`control device, for example. A liquid recovery device 6 composed of a tank of the
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`liquid, and a suction pump, for example recovers water on the wafer W via a
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`predetermined inflow nozzle or the like. The temperature of the liquid 7 is set to
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`substantially the same temperature as, for example, the temperature in a
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`chamber which houses the projection exposure apparatus of this example. A
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`discharge nozzle 21a having a narrow distal end and two inflow nozzles 23a and
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`23b (see Fig. 2) each having a widened distal end are disposed in such a way that
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`the front end of the lens 4 of the projection optical system PL is arranged
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`between the discharge nozzle 21a and the inflow nozzles 23a and 23b with
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`respect to the X'direction. The discharge nozzle 21a is connected to the liquid
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`supply device 5 via a supply pipe 21 and the inflow nozzles 23a and 23b are
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`connected to the liquid recovery device 6 via a recovery pipe 23. Furthermore, a
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`pair of nozzles are disposed in an arrangement obtained by rotating the pair of
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`the discharge nozzle 21a and the inflow nozzles 23a and 23b by substantially 180°
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`and also two pairs of a discharge nozzle and inflow nozzles are disposed in such a
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`way that the front end of the lens 4 is arranged between the discharge nozzles
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`and the inflow nozzles with respect to the Y-direction.
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`Fig. 2 shows the positional relationship between the front end 4A of the
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`lens 4 of the projection optical system PL shown in Fig. 1, the wafer W and the
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`two pairs of the discharge nozzle and the inflow nozzles between which the front
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`end 4A is interposed in the X'direction. In Fig. 2, the discharge nozzle 21a is
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`disposed on the +X'direction side of the front end 4A and the inflow nozzles 23a
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`and 23b are disposed on the 'X'direction side of the front end 4A. In addition, the
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`inflow nozzles 23a and 23b are disposed so as to spread in a fan-like form with
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`respect to an axis passing through the center of the front end 4A and parallel to
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`the X-axis. Furthermore, another pair of a discharge nozzle 22a and inflow
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`nozzles 24a and 24b are disposed in an arrangement obtained by rotating the
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`pair of the discharge nozzle 21a and the inflow nozzles 23a and 23b by
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`substantially 180°, with the discharge nozzle 22a connected to the liquid supply
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`device 5 via a supply pipe 22 and the inflow nozzles 24a and 24b connected to the
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`liquid recovery device 6 via a recovery pipe 24.
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`Furthermore, Fig. 3 shows the positional relationship between the front
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`end 4A of the lens 4 of the projection optical system PL shown in Fig. 1 and the
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`two pairs of the discharge nozzle and the inflow nozzles between which the front
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`end 4A is interposed in the Y-direction. In Fig. 3, the discharge nozzle 27a is
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`disposed on the +Y'direction side of the front end 4A and the inflow nozzles 29a
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`and 29b are disposed on the -Y-direction side of the front end 4A, with the
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`discharge nozzle 27a connected to the liquid supply device 5 via a supply pipe 27
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`and the inflow nozzles 29a and 29b connected to the liquid recovery device 6 via a
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`recovery pipe 29. Furthermore, another pair of the discharge nozzle 28a and the
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`inflow nozzles 30a and 30b are disposed in an arrangement obtained by rotating
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`the pair of the discharge nozzle 27 a and the inflow nozzles 29a and 29b by
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`substantially 180°, with the discharge nozzle 28a connected to the liquid supply
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`device 5 via a supply pipe 28 and the inflow nozzles 30a and 30b connected to the
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`liquid recovery device 6 via a recovery pipe 30. The liquid supply device 5
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`supplies temperature-controlled liquid to the space between the front end 4A of
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`the lens 4 and the wafer W via at least one of the supply pipes 21, 22, 27, and 28.
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`The liquid recovery device 6 recovers the liquid via at least one of the recovery
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`pipes 23, 24, 29, and 30.
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`The following describes the supply and recovery method of the liquid 7.
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`In Fig. 2, the liquid supply device 5 supplies the liquid 7 to the space
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`between the front end 4A of the lens 4 and the wafer W via the supply pipe 21
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`and the discharge nozzle