JPH10335235A - Aligner, optical cleaning method thereof and manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aligner capable of keeping high optical performance by removing deposits such as water content or organic substances, even if they are deposited on the surface of an optical element. SOLUTION: This aligner comprises illumination optical systems 2-9 for illuminating a pattern on a projection master plate 10 which an optical beam from an optical source and a projection optical system 11 for imaging the beam which has passed through the pattern on a photosensitive substrate 12, thereby exposing the substrate. In this case, an optical path deflector 13 is removably disposed in any one of spaces in the aligner, so as to form an optical path to the substrate 12 to be different from the optical path for exposing the substrate 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention manufactures devices such as semiconductor devices such as LSIs, imaging devices such as CCDs, liquid crystal display devices, and thin-film magnetic heads (hereinafter collectively referred to as semiconductor devices). The present invention relates to a projection exposure apparatus for exposing a pattern on a projection original such as a mask (or reticle) to a photosensitive substrate such as a wafer in an optical lithography process, and particularly to an optical cleaning method.

[0002]

2. Description of the Related Art An optical lithography process is a main process for manufacturing a semiconductor device. With the increase in the degree of integration of a semiconductor device, a projection exposure apparatus used in the optical lithography process has made great progress. I have. The resolving power of the projection optical system mounted on the projection exposure apparatus is represented by the relationship of R = k × λ / NA, as is well known by the Rayleigh equation. Here, R is the resolution of the projection optical system,
λ is the wavelength of light for exposure, NA is the numerical aperture of the projection optical system, k
Is a constant determined by the process in addition to the resolution of the resist. As can be seen from the above formula, in order to realize the resolution required by the projection optical system in response to the high integration of semiconductor devices, the wavelength of the light source for exposure must be shortened and the numerical aperture of the projection optical system must be reduced Efforts to increase the NA are continuing. In recent years, KrF with an output wavelength of 248 nm
(Krypton fluoride) excimer laser as the light source for exposure,
Exposure apparatuses having a projection optical system having a numerical aperture of 0.6 or more have been commercialized, and exposure of fine patterns as large as 0.25 μm has been realized.

In particular, recently, as a light source following a KrF excimer laser, an ArF having an output wavelength of 193 nm is used.
(Argon fluoride) excimer lasers are attracting attention. If an exposure apparatus using this ArF excimer laser as an exposure light source can be realized, 0.18 μm to 0.13-0.
It is expected that fine processing down to 15 μm will be possible. The output wavelength of this ArF excimer laser (19)
In the wavelength range of 3 nm), materials that can be used as lenses are limited to two types at this stage, synthetic quartz glass and calcium fluoride (fluorite), from the viewpoint of transmittance. Therefore, as an optical material for this type of exposure apparatus, a material having sufficient transmittance and internal uniformity has been developed. In the case of synthetic quartz glass, the internal transmittance is 0.995 / cm or more, and calcium fluoride is used. Has reached negligible levels of internal absorption. When an ArF excimer laser is used as the light source for exposure, the material for the antireflection film coated on the surface of the optical material is also the output wavelength of the KrF excimer laser (248 nm).
The selection range is much narrower than that in the wavelength range of m), and the degree of freedom in design is greatly restricted. However, due to vigorous development efforts, the loss on each lens surface is 0.005.
The following levels have been realized.

[0004]

In an exposure apparatus using an ArF excimer laser as a light source, the characteristics of an optical member such as a lens are changed by heat generated by absorption of light by an optical material or an anti-reflection film, and this is a characteristic of an image forming characteristic. It becomes a fluctuation factor. Therefore, it is essential to achieve as high a transmittance as possible and to make the change in thermal characteristics as small as possible. However, in the case of light in the deep ultraviolet region of 200 nm or less, even if the absorption by the optical material and the antireflection film is reduced to the above level, when the optical components for the exposure apparatus are handled in the working environment in the air, Due to moisture and organic matter
The inventors' experiments have revealed that there is a problem that the transmittance of an optical component such as a lens rapidly decreases. The amount of absorption is, for example, 0.1 per lens.
01, which is larger than the absorption inside the optical component and the absorption by the antireflection film, and is the largest absorption factor.

A method of irradiating an ultraviolet ray as a method of cleaning the adhered matter adhered to the surface of the optical component is disclosed in, for example, Japanese Patent Application Laid-Open No.
This is known from 294705. However,
This technique relates to a method of cleaning a single optical component, and does not disclose a method of cleaning the entire optical component or a main part of the exposure device after the optical component is assembled as an exposure device. In addition, although a temporary cleaning effect is exhibited by the irradiation of ultraviolet light, the surface of the optical component is activated by the ultraviolet light, and when left in a normal working environment thereafter, it becomes easier to adsorb ambient moisture and organic substances. This has been found by experiments of the present inventors.

[0006] Therefore, even if the optical parts are cleaned with ultraviolet rays, it is practically impossible to construct a projection optical system by assembling optical parts such as lenses in a state where they are completely isolated from moisture and organic substances. Is not possible in
This is a major obstacle in realizing an optical system of an exposure apparatus for an ArF excimer laser. The present invention has been made in view of the above problems, and even when moisture and organic substances adhere to the surface of an optical element, these adhered substances are eliminated to maintain high optical performance. An object of the present invention is to provide an exposure apparatus, a method for cleaning an exposure apparatus, and a method for manufacturing a semiconductor device using the method.

[0007]

According to the present invention, when exposing a photosensitive substrate, the optical components of the exposing apparatus are self-cleaned by exposure light. Light cleaning is performed even when the cleaning is not performed, thereby solving the above problem. Further, in the present invention, the transmittance of the projection optical system or the illumination optical system or the illuminance distribution on the image plane of the projection optical system changes due to some factors during the exposure process, or the illumination coherency is changed during the exposure process. In such a case, the transmittance of the projection optical system and the illumination optical system and the illuminance distribution on the image plane of the projection optical system may change, so that the exposure operation is temporarily stopped not only during the exposure process but also during the exposure process. Then, light cleaning is performed to solve the above problem.

That is, the exposure apparatus according to the present invention moves and scans the optical path on the photosensitive substrate side from a predetermined space in the exposure apparatus to an optical path different from the optical path when exposing the photosensitive substrate. An optical path scanning system is provided. As the optical path scanning system, the optical path is deflected to the predetermined space so that the optical path on the photosensitive substrate side with respect to the predetermined space in the exposure apparatus is different from the optical path when exposing the photosensitive substrate. It is preferable that the members are arranged so that they can be inserted and removed. Further, as another optical path scanning system, the photosensitive substrate side than a predetermined part of the optical member in the exposure apparatus, so that the optical path is different from the optical path when performing exposure of the photosensitive substrate,
Some of the optical members may be movably arranged.

In addition, a shutter is disposed between the projection optical system and the photosensitive substrate so as to be insertable and removable so that the photosensitive substrate is not exposed by the cleaning light. The replacement of the photosensitive substrate, the alignment process, and the like can be performed in parallel, thereby making it possible to reduce the decrease in throughput due to the optical cleaning process. In addition, the surface on the side of the projection optical system of the shutter is used as a reflection surface, and the cleaning light that has passed through the projection optical system is reflected back to the projection optical system to further enhance the light cleaning effect. In addition, the stage on which the photosensitive substrate is mounted is provided with a transmitted light detector for measuring the intensity of the light beam transmitted through the projection optical system, or reflected on the optical path in the exposure apparatus by the reflection surface of the shutter surface. A reflected light detector that measures the intensity of the light beam is provided, and further in the optical path on the light source side than the projection optical system,
An incident light detector for measuring the intensity of a light beam incident from the light source side is provided so that a change in transmittance of the illumination optical system and the projection optical system can be measured. Therefore, based on the measurement result, a light cleaning step is performed. Start and end can be determined.

[0010]

FIG. 1 shows a first embodiment of the present invention. A light beam emitted from the ArF excimer laser 1 is shaped by the beam shaping optical system 2 into a shape corresponding to the shape of the incident surface of the fly-eye lens 3, then divided by the fly-eye lens 3, and emitted from the fly-eye lens 3. A plurality of secondary light sources are formed in the vicinity. The luminous flux from the multiple secondary light sources is
After the shape is restricted by the aperture stop 4, the front group 5 of the condenser lens
a is superimposed on the field stop 6 by the condenser lens rear group 5b to form uniform illumination light. The uniform illumination light formed on the field stop 6 is enlarged or reduced at a desired magnification by the front group 7 of the field stop image forming optical system and the rear group 9 of the field stop image forming optical system. Light up. The fine pattern formed on the mask 10 is projected and exposed by a projection optical system 11 onto a wafer 12 as a photosensitive substrate.

The front group 5a of the condenser lens, the rear group 5b of the condenser lens, the front group 7 of the imaging optical system, and the rear group 9 of the imaging optical system
A condenser optical system for condensing light from a plurality of secondary light sources formed by a fly-eye lens 3 as an optical integrator and illuminating the mask 10 in a superimposed manner is configured. Note that the optical integrator is not limited to the fly-eye lens 3 configured by bundling a large number of rod-shaped optical elements, but may be an internal reflection type rod-shaped optical member. Without limitation, a plurality of optical integrators may be arranged in series.

As described above, when the wavelength is extremely short, such as the light beam emitted from the ArF excimer laser 1, the surface of each optical element from the illumination optical systems 2 to 9 to the projection optical system 11 is exposed to air. Water and organic substances floating on the surface are attached and contaminated, causing a decrease in the transmittance of the refraction element and a decrease in the reflectance of the reflection element. These contaminants are self-cleaned by the light beam from the ArF excimer laser 1 when the light beam from the ArF excimer laser 1 passes to perform the exposure of the wafer 12. Go being. Therefore, in the present embodiment, prior to exposure of the wafer 12, a light beam from the ArF excimer laser 1 is passed through each optical element, so that contamination on the surface of the optical element can be cleaned.

First, the effect of cleaning is greater as the energy density is higher. Therefore, the projection optical system 11 can be used without considering the time loss required for attaching and detaching the mask 10.
If attention is paid only to the above cleaning, it is preferable to perform cleaning with the mask 10 removed. However, the numerical aperture of the projection optical system is configured so as to capture not only the light flux from the illumination optical system that has passed through the mask 10 but also the diffracted light diffracted by the mask 10. It is smaller than the numerical aperture of the optical system. Therefore, in a state where the mask 10 is removed, a portion that is not exposed to light is generated around the lens constituting the projection optical system, and a portion that is not cleaned is generated around the lens. Further, even when viewed only in a portion where light is irradiated, there is a possibility that an insufficiently cleaned portion may occur because the energy density is lower at the peripheral portion of the lens than at the central portion. Similarly, even if optical cleaning is performed with the mask 10 mounted, the peripheral portion of the lens has a lower energy density than the central portion, so that insufficient cleaning may occur.

For this reason, in this embodiment, a rotatable deflection prism 13 is disposed between the rear group 9 of the field stop imaging optical system 9 and the mask 10 so that it can be inserted and removed. The deflection prism 13
The drive unit 22 is driven to be inserted into and removed from the optical path and is driven to rotate. The drive unit 22 is controlled by the control unit 21. With this configuration, when light cleaning is to be performed, the deflection prism 13 can be inserted into the optical path to deflect light incident on the projection optical system 11 and further rotate the deflection prism 13, and thus the projection optical system can be rotated. The peripheral portion of each lens of the system 11 is irradiated with a light beam having an amount of light capable of obtaining a sufficient cleaning effect. At this time, the argument Δ by the argument prism 13 is given by Δ ≧ NA _p −NA _i when the numerical aperture of the illumination optical system is NA _i and the numerical aperture of the projection optical system is NA _p when performing cleaning irradiation. It is desirable that It is not necessary to reduce the numerical aperture of the illumination optical system during light cleaning.
_i is preferably the maximum numerical aperture of the illumination optical system.

In this embodiment, the projection optical system 11
By disposing the shutter 14 that is driven into and out of the optical path by the driving device 23 between the and the wafer 12,
Prevents the wafer 12 from being exposed during light cleaning,
Thus, the wafer exchange and the alignment process during the light cleaning can be performed at the same time. Further, the surface of the shutter 14 on the side of the projection optical system 11 is formed as a reflection mirror, and the cleaning light that has passed through the projection optical system 11 is reflected and reversed to further enhance the cleaning effect.
At this time, by configuring the driving device 23 so that the direction of the normal line of the reflection mirror can be tilted in an arbitrary direction without matching the optical axis of the projection optical system, a more efficient cleaning effect can be obtained.

In the light cleaning step, cleaning may be performed while the mask 10 to be exposed is arranged. However, in this case, the energy of the cleaning light incident on the projection optical system 11 is reduced by the transmittance of the mask 10, so that the cleaning time increases. On the other hand, if cleaning is performed by removing the mask 10, the cleaning time is shortened.
It takes time to insert and remove 0s. Therefore, when the time required for attaching and detaching the mask 10 is longer, the cleaning may be performed while the mask 10 is arranged. In addition, the place where the deflection prism 13 is arranged may be any position on the near side with respect to a portion requiring light cleaning. Therefore, for example, when the optical cleaning of the projection optical system 11 is mainly performed, the projection optical system 11 may be disposed between the mask 10 and the projection optical system 11 in addition to being disposed between the field stop imaging optical system rear group 9 and the mask 10. it can. If desired, it can be arranged inside the illumination optical system or inside the projection optical system.

In this embodiment, the stage 15 on which the wafer is placed is used to measure the light intensity on the wafer surface.
A transmission light detector 16 for measuring the intensity of a light beam transmitted through the projection optical system 11 is attached to the transmission light detector 1.
The output of 6 is input to the transmittance measuring device 20. With this configuration, the ArF excimer laser 1 and the projection optical system 1
The change in the total transmittance of all the optical elements up to 1 is measured as follows. That is, the stage 15 is driven to dispose the transmitted light detector 16 in the optical path of the projection optical system 11, and the shutter 14 is opened to measure the output of the transmitted light detector 16. Then, this output is monitored, and the state where the output is saturated is stored in the transmittance measuring device 20 as the best light intensity. After that, the light intensity at the present time is
By comparing with the best light intensity stored in 0,
The total transmittance of all the optical elements at the present time can be immediately known. Therefore, it is possible to easily determine whether or not the cleaning process should be started and whether or not to end the cleaning process.

Note that the transmittance measuring device 20 includes a stage 1
Transmitted light detector 16 as a photoelectric detector provided on 5
Is measured on the image plane of the projection optical system 11 to determine whether or not to start the optical cleaning step, but the present invention is not limited to this. That is, the transmittance measuring device 2
0 measures the transmittance distribution on the image plane of the projection optical system 11, that is, the illuminance distribution, based on the output of the transmitted light detector 16 serving as a photoelectric detector provided on the stage 15; It is needless to say that the configuration may be such that it is determined whether or not the distribution is obtained, and whether or not the light cleaning process is started is determined based on the determination.

FIG. 2 shows another embodiment of the present embodiment. In the configuration of FIG. 1, when the shutter 14 is closed, the light intensity cannot be measured on the wafer surface.
Therefore, in the configuration of FIG. 2, a half mirror is arranged between the aperture stop 4 in the illumination optical system and the front group 5a of the condenser lens, and the reflected light path of the light beam incident on the half mirror from the reflection surface side of the shutter 14 is A reflected light detector 17 for measuring the intensity of this light beam is provided. According to this configuration, the change in the total transmittance between the forward path of the optical element from the ArF excimer laser 1 to the aperture stop 4 and the reciprocal path of the optical element from the front lens group 5a to the projection optical system 11 is constantly monitored. Monitoring can be performed, and thus transmittance measurement can be performed in real time during the cleaning process, which is useful for determining the end of the cleaning process. The position at which the half mirror is interposed does not particularly matter, and can be interposed at any position in the illumination optical system or the projection optical system.

FIG. 3 shows still another embodiment of the present invention. In the configuration of FIG. 1 and the configuration of FIG. 2, if the output of the ArF excimer laser 1 fluctuates, it is erroneously recognized that the transmittance has changed by that amount. Therefore, in the configuration of FIG.
In addition to the provision of a transmitted light detector 16 in the illumination optical system 5, a half mirror is arranged between the aperture stop 4 in the illumination optical system and the front group 5a of the condenser lens to reflect a light beam incident on the half mirror from the ArF excimer laser 1 side. An incident light detector 18 for measuring the intensity of this light beam is provided on the optical path, and the transmittance is obtained based on the difference between the outputs of the incident light detector 18 and the transmitted light detector 16. According to this configuration, it is possible to measure the change in the transmittance of the optical element from the condenser lens front group 5 a to the projection optical system 11 irrespective of the change in the output of the ArF excimer laser 1. In addition, the transmittance measuring device 20 shown in FIG. 3 transmits the transmittance distribution on the image plane of the projection optical system 11 based on the output of the transmitted light detector 16 as a photoelectric detector provided on the stage 15. That is, the configuration may be such that the illuminance distribution is measured to determine whether or not a predetermined illuminance distribution has been achieved, and thereby to determine whether to start the light cleaning step.

FIG. 4 shows still another embodiment of the present embodiment. In the configuration of FIG. 3, when the shutter 14 is closed, the light intensity cannot be measured on the wafer surface.
Therefore, in the configuration of FIG. 4, a half mirror is arranged between the aperture stop 4 in the illumination optical system and the front lens group 5a,
An incident light detector 18 for measuring the intensity of the light beam incident on the half mirror from the F excimer laser 1 side is provided on the reflected light path of the light beam incident on the half mirror from the reflection surface side of the shutter 14. A reflected light detector 17 for measuring the intensity of this light beam is provided, and the transmittance is obtained based on the difference between the output of the incident light detector 18 and the output of the reflected light detector 17. According to this configuration, the ArF excimer laser 1
Irrespective of the output change and the shutter 14 is kept closed, the change of the transmittance of the optical element from the condenser lens front group 5a to the projection optical system 11 can be constantly monitored.

FIG. 5 shows a second embodiment of the present invention.
The method of changing the optical path for performing the light cleaning is different from that of the first embodiment. That is, as shown in FIG. 5, the optical path is changed by two-dimensionally vibrating the bending mirror 8 disposed between the front group 7 and the rear group 9 of the field stop imaging optical system. Although the mirror 8 is rotated about the center of the mirror 8 in FIG. 2, the present invention is not limited to this, and the rotation center may be set to another position, or may be combined with not only rotation but also shift. . The arrangement of the mirror 8 is not limited to the position between the front group 7 and the rear group 9 of the field stop imaging optical system, and may be arranged at a convenient position of the illumination optical system. However, in the optical system after the mirror 8, the effective diameter according to the numerical aperture of the illumination optical system becomes insufficient, and the projection optical system 1
A sufficient effective diameter corresponding to the numerical aperture of 1 is required.

FIG. 6 shows a third embodiment of the present invention.
The method of changing the optical path for performing the light cleaning is different from that of the first embodiment. That is, as shown in FIG. 6, the optical path is changed by two-dimensionally decentering the rear group 9 of the field stop imaging optical system in a plane direction orthogonal to the optical axis. At this time, it is more effective to make the movable three-dimensionally in addition to the movement in the optical axis direction. The movable optical system is not limited to the rear group 9 of the field stop imaging optical system. For example, the front group 5a, the rear group 5b, and the front group 7 of the field stop imaging optical system in FIG. Any optical system may be movable. However, similarly to the second embodiment, the movable optical system and subsequent optical systems need to have a sufficient effective diameter according to the numerical aperture of the projection optical system 11.

In each of the embodiments described above, the light cleaning step is mainly performed prior to the exposure step. However, the transmittance of the projection optical system 11 and the illumination optical system and the projection optical system The illuminance distribution on the image plane of the system 11 may change. For this reason, it is preferable to temporarily stop the exposure operation during the exposure process and periodically execute the optical cleaning process. Further, when the illumination coherency (σ value) is changed by changing the aperture diameter of the aperture stop 4 in the illumination optical system during the exposure process, the projection optical system 11 and the illumination optical system need to perform exposure. And the desired illuminance distribution on the image plane of the projection optical system 11 may not be obtained. Therefore, when changing the illumination coherency (σ value), it is preferable to temporarily stop the exposure operation during the exposure step and perform the light cleaning step. It should be noted that the σ value as the illumination coherency is determined by setting the numerical aperture of the illumination optical system to N.
_Let A _i be the numerical aperture of the projection optical system and NA _p be the definition of σ = NA _i / NA _p .

[0025]

As described above, according to the present invention, in particular, Ar
In a projection exposure apparatus using a far-ultraviolet wavelength such as an F excimer laser, moisture and organic substances adhering to an optical system constituting the exposure apparatus can be removed by light cleaning, so that a good reticle pattern image can be formed on a photosensitive substrate. Can be transferred to That is, in the optical lithography step including the exposure method, even if the transmittance of the projection optical system is reduced, the transmittance of the projection optical system can be sufficiently recovered by newly adopting the light cleaning step, Since a finer pattern can be transferred onto the photosensitive substrate, a highly integrated semiconductor device such as an LSI can be manufactured. In addition, if the light cleaning process according to the present invention is used when manufacturing a projection optical system, the assembly and adjustment work of the projection optical system under a normal working environment becomes possible, and the transmittance of the projection optical system is sufficiently secured. can do.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a first embodiment of the present invention.

FIG. 2 is a schematic sectional view showing another embodiment of the first embodiment.

FIG. 3 is a schematic sectional view showing still another mode of the first embodiment.

FIG. 4 is a schematic sectional view showing still another mode of the first embodiment.

FIG. 5 is a schematic sectional view showing a second embodiment of the present invention.

FIG. 6 is a schematic sectional view showing a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... ArF excimer laser 2 ... Beam shaping optical system 3 ... Fly eye lens 4 ... Aperture stop 5a ... Condenser lens front group 5b ... Condenser lens rear group 6 ... Field stop 7 ... Field stop imaging optical system front group 8 ... Mirror 9: Field stop imaging optical system rear group 10 ... Mask 11 ... Projection optical system 12 ... Wafer 13 ... Deflection prism 14 ... Shutter 15 ... Stage 16 ... Transmitted light detector 17 ... Reflected light detector 18 ... Incident light detection Instrument 20: Transmittance measuring device 21: Control device 22, 23: Drive device

Claims (17)

[Claims] An illumination optical system for illuminating a pattern formed on a projection original with a light beam from a light source, and a projection for exposing the photosensitive substrate by forming an image of a light beam transmitted through the pattern on a photosensitive substrate. In an exposure apparatus having an optical system, an optical path on the photosensitive substrate side than a predetermined space in both optical systems is different from an optical path when performing exposure of the photosensitive substrate. An exposure apparatus, wherein an optical path deflecting member is disposed in the predetermined space so as to be insertable and removable. 2. The exposure apparatus according to claim 1, wherein a rotatable deflection prism is removably disposed between the illumination optical system and the projection master. 3. An illumination optical system for illuminating a pattern formed on a projection original with a light beam from a light source, and a projection for exposing the photosensitive substrate by forming an image of a light beam transmitted through the pattern on a photosensitive substrate. An optical system, wherein an optical path closer to the photosensitive substrate than a predetermined part of the optical members of the two optical systems is different from an optical path when performing exposure of the photosensitive substrate. An exposure apparatus, wherein the some of the optical members are movably arranged so as to be as follows. 4. An exposure apparatus according to claim 3, wherein said some optical members are rotatable mirrors arranged in said illumination optical system. 5. An exposure apparatus according to claim 3, wherein said some optical members are movable lenses disposed in said illumination optical system. 6. An exposure apparatus according to claim 1, wherein a shutter is detachably provided between said projection optical system and said photosensitive substrate. 7. The exposure apparatus according to claim 6, wherein a surface of the shutter on the projection optical system side is formed as a reflection surface. 8. The exposure apparatus according to claim 1, wherein a transmission light detector for measuring an intensity of a light beam transmitted through the projection optical system is provided on a stage on which the photosensitive substrate is mounted. apparatus. 9. The exposure apparatus according to claim 7, further comprising a reflected light detector for measuring the intensity of the light beam reflected by the reflection surface, in any one of the optical paths in the exposure apparatus. 10. The exposure apparatus according to claim 8, further comprising an incident light detector for measuring an intensity of a light beam incident from the light source side in an optical path on the light source side with respect to the projection optical system. 11. An illumination optical system for illuminating a pattern formed on a projection original, and a projection optical system for exposing the photosensitive substrate by forming a light beam transmitted through the pattern on a photosensitive substrate. In the light cleaning method of the exposure apparatus, a step of removing the photosensitive substrate out of an optical path or inserting a shutter immediately before the photosensitive substrate; and a method of removing the photosensitive substrate from a predetermined space in both the optical systems. Inserting a light path deflecting member into the predetermined space so that the light path on the substrate side is different from the light path when performing exposure of the photosensitive substrate. Cleaning method. 12. An illumination optical system for illuminating a pattern formed on a projection original, and a projection optical system for exposing the photosensitive substrate by forming a light beam transmitted through the pattern on a photosensitive substrate. In the light cleaning method of the exposure apparatus, a step of removing the photosensitive substrate out of the optical path or inserting a shutter immediately before the photosensitive substrate; and a step of removing a predetermined part of the optical members of the two optical systems. Changing the position or orientation of the part of the optical members so that the optical path on the photosensitive substrate side is different from the optical path when performing exposure of the photosensitive substrate. Cleaning method for an exposure apparatus. 13. An illumination optical system for illuminating a pattern formed on a projection original, and a projection optical system for imaging a light beam transmitted through the pattern on a photosensitive substrate to expose the photosensitive substrate. In a method of manufacturing a semiconductor device using an exposure apparatus, a step of exposing the photosensitive substrate by arranging the photosensitive substrate in an optical path, and removing the photosensitive substrate out of the optical path or immediately before the photosensitive substrate After inserting the shutter, the optical path on the photosensitive substrate side than a predetermined space in the two optical systems is different from the optical path when performing exposure of the photosensitive substrate, the predetermined optical path, Inserting a light path deflecting member into the space defined in (a). 14. An illumination optical system for illuminating a pattern formed on a projection original, and a projection optical system for exposing the photosensitive substrate by imaging a light beam transmitted through the pattern on the photosensitive substrate. In a method of manufacturing a semiconductor device using an exposure apparatus, a step of exposing the photosensitive substrate by arranging the photosensitive substrate in an optical path, and removing the photosensitive substrate out of the optical path or immediately before the photosensitive substrate After inserting the shutter, an optical path on the photosensitive substrate side of a predetermined part of the optical members of the two optical systems is different from an optical path when performing exposure of the photosensitive substrate. Changing the position or orientation of the part of the optical members. 15. An illumination optical system for illuminating a pattern formed on a projection original with a light beam from a light source, and a projection for exposing the photosensitive substrate by forming an image of the light beam via the pattern on the photosensitive substrate. An exposure system having an optical system, wherein the optical path closer to the photosensitive substrate than a predetermined space in the two optical systems is moved and scanned to an optical path different from the optical path when exposing the photosensitive substrate. An exposure apparatus comprising an optical path scanning system. 16. An illumination optical system for illuminating a pattern formed on a projection original with a light beam from a light source, and a projection for exposing the photosensitive substrate by forming an image of the light beam via the pattern on the photosensitive substrate. In an optical cleaning method for an exposure apparatus having an optical system, during the exposure step of the exposure apparatus or prior to the exposure step of the exposure apparatus, the photosensitive substrate side more than a predetermined space in both the optical systems. An optical cleaning method comprising a step of moving and scanning an optical path to an optical path different from an optical path when exposing the photosensitive substrate. 17. A method for manufacturing a semiconductor device, comprising an exposure step of illuminating a pattern formed on a projection original with a light beam from an illumination optical system and exposing the pattern onto a photosensitive substrate via the projection optical system. During the exposure step or prior to the exposure step, an optical path on the photosensitive substrate side relative to a predetermined space in both of the optical systems is different from an optical path when the photosensitive substrate is exposed. A method for manufacturing a semiconductor device, comprising: a step of moving and scanning a semiconductor device.