JP2003115433A - Exposure method and aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure method and an aligner for decomposing a contaminant that is present in a light path space for accurately and stably performing exposure treatment. SOLUTION: The aligner EX has an illumination optical system IL for illuminating a mask M with exposure light EL, and a projection optical system PL for projecting a pattern on the mask M to a wafer W. The projection optical system PL has a binary optical element L2 for diffusing light. Then, at a position that is illuminated with light from the binary optical element L2 in a mirror cylinder PK for surrounding the projection optical system PL, a titanium oxide thin film T for optically decomposing the contaminant that is present in the light path space LS is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure method and exposure apparatus used in the manufacturing process of semiconductor devices and liquid crystal display devices.

[0002]

2. Description of the Related Art Conventionally, when a semiconductor device or a liquid crystal display device is manufactured by using a lithographic technique, a mask on which a pattern is formed is illuminated with exposure illumination light (exposure light) and an image of the pattern of the mask is obtained. There is used an exposure apparatus for projecting and exposing the light on a photosensitive substrate such as a semiconductor wafer or a glass plate coated with a photosensitizer such as a photoresist through a projection optical system. In recent years, with the demand for miniaturization of the pattern shape projected on the shot area on the substrate, the exposure light used tends to have a shorter wavelength, and in place of the mercury lamp that has been the mainstream until now, KrF has been used. Excimer laser (248 nm), ArF excimer laser (19
An exposure apparatus using 3 nm) is being put to practical use. Further, the development of an exposure apparatus using an F ₂ laser (157 nm) is underway with the aim of further miniaturizing the pattern shape.

When the exposure light is vacuum ultraviolet light of about 190 nm or less, it has a strong absorption characteristic for light in such a wavelength range such as oxygen molecules, water molecules and carbon dioxide molecules in the optical path space which is a space through which the exposure light passes. A substance having
If the “light absorbing material” is present, the exposure light is dimmed and cannot reach the substrate with sufficient intensity. Therefore, in the exposure apparatus using the vacuum ultraviolet light, in order to transfer the image of the pattern of the mask onto the substrate with the exposure light having a sufficient light amount, the optical path space through which the exposure light passes is used as a closed chamber to absorb the light absorbing material from the outside. In addition to blocking the inflow of light, the work of reducing the light-absorbing substance existing in the optical path space during the exposure process is performed. Conventionally, as a method of reducing the light-absorbing substance in the optical path space, a substance such as helium, argon, or nitrogen (hereinafter, referred to as “inert gas”) having a property of having low absorptivity for exposure light is provided in the optical path space. There is a method of supplying and filling this optical path space with an inert gas.

[0004]

However, contaminants such as organic substances existing in the optical path space through which the exposure light passes may adhere to the surface of the optical element (lens) and the optical element may become cloudy. This fogging causes a decrease in the transmittance of the optical element or causes unevenness in the transmittance of the optical element, which causes unevenness in the illuminance on the photosensitive substrate, resulting in a decrease in exposure accuracy. Therefore, it is necessary to remove the contaminant attached to the surface of the optical element, but it is not easy to remove this contaminant. As a method for removing contaminants adhering to the surface of the optical element, there is photocleaning in which the contaminants are directly irradiated with ultraviolet light. However, in an exposure apparatus using vacuum ultraviolet light as a light source, it is necessary to reduce the oxygen concentration in the optical path space as much as possible, so that there is a problem that the amount of ozone generated is small and the effect of optical cleaning cannot be sufficiently obtained.

As described above, in the exposure apparatus using vacuum ultraviolet light, it is necessary to eliminate oxygen, which is a light-absorbing substance, in order to perform exposure processing using a sufficient amount of exposure light, while the optical element surface There is a contradiction that oxygen is required for optical cleaning to remove contaminants adhering to the substrate, and it is necessary to seal the optical path space through which the exposure light passes, so the interior can be easily cleaned. Can not. As described above, in the exposure apparatus using vacuum ultraviolet light, a great deal of labor is required to maintain the cleanliness of the optical path space.

The present invention has been made in view of such circumstances, and even if vacuum ultraviolet light is used as exposure light, contaminants existing in the optical path space can be easily decomposed,
An object of the present invention is to provide an exposure method and an exposure apparatus that can perform stable exposure processing with high accuracy.

[0007]

In order to solve the above-mentioned problems, the present invention employs the following configurations associated with FIGS. 1 to 4 shown in the embodiments. The exposure method of the present invention is an exposure method of exposing a pattern on the first surface (M) to the second surface (W) with the exposure light (EL), which is diffusion for diffusing light on the optical path of the exposure light (EL). The members (L2, Ma) are arranged and the optical path space (L) through which the exposure light (EL) passes
In S), a photocatalyst (T) capable of photolyzing the contaminants existing in the optical path space (LS) is provided at a position where the light from the diffusion member (L2, Ma) is irradiated, and the diffusion member (L
2, Ma) while irradiating the photocatalyst (T) with diffused light generated by irradiating the light on the second surface (M), and exposing the pattern on the first surface (M) to the second surface (W).

The exposure apparatus (EX) of the present invention uses the exposure light (E
In the exposure device that exposes the pattern on the first surface (M) to the second surface (W) by L), a diffusing member (L2, Ma) that is arranged on the optical path of the exposure light (EL) and diffuses the light. , The light path space (LS) through which the exposure light (EL) passes is provided at the position where the light from the diffusion member (L2, Ma) is irradiated, and the contaminants existing in the light path space (LS) can be photodecomposed. And a different photocatalyst (T).

According to the present invention, the diffusion member (L2, Ma)
Light path space (LS) at the position where the light diffused by
Since the photocatalyst (T) capable of photolyzing the pollutant existing in the optical path space (LS) is provided, the pollutant existing in the optical path space (LS) can be easily and efficiently decomposed and reduced by the photocatalytic reaction of the photocatalyst (T). it can. Therefore, it is possible to perform the exposure process with high accuracy and stability.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An exposure apparatus of the present invention will be described below with reference to FIG. FIG. 1 is an overall configuration diagram showing a first embodiment of an exposure apparatus of the present invention. 2 is a diagram showing a binary optical element as a diffusing member. In the following description, the optical axis AX direction of the projection optical system PL is the Z direction, and the horizontal directions orthogonal to this Z direction are the X direction and the Y direction. Further, the rotation directions around the respective axes are set to θZ, θY, and θX.

As shown in FIG. 1, the exposure apparatus EX includes an illumination optical system IL for irradiating a mask (first surface) M with exposure light EL.
And a projection optical system PL for projecting the pattern of the mask M illuminated by the exposure light EL onto the wafer (second surface) W.

The illumination optical system IL emits light from the light source 1 and passes the wavelength filter 3 which passes only the wavelength necessary for exposure among the light flux deflected by the first deflection mirror 2a, and the light flux which has passed through this wavelength filter 3. A fly-eye integrator 4 that adjusts the light flux having a substantially uniform illuminance distribution to convert it into exposure light EL, a second deflection mirror 2b that deflects the exposure light EL from the fly-eye integrator 4 and guides it to the lens system 6, and a mask M. And a third deflection mirror 2c that guides the exposure light EL, whose illumination range is defined by the blind part BL and which has passed through the lens system 7, to the mask M. In this embodiment, the light source 1 is composed of an F ₂ laser (oscillation wavelength 157 nm) and emits vacuum ultraviolet light. Each optical element (lens) forming the illumination optical system IL is arranged in the illumination system housing IK.

The mask M is placed in the mask chamber 10. The mask chamber 10 includes a mask holder MH that holds the mask M by vacuum suction, and a lens barrel (projection system housing) P of the illumination system housing IK and the projection optical system PL.
It is covered with a partition wall MK that is joined to K without a gap. The interior space of the illumination system housing IK and the mask chamber 10
A transparent window 8 is arranged between the and. An opening for loading / unloading the mask M and an opening / closing door (not shown) for opening / closing the opening are provided on the side wall of the partition MK. The mask chamber 10 is hermetically closed by closing the opening / closing door. The mask holder MH has an opening corresponding to a pattern area where the pattern on the mask M is formed, and can be finely moved in the X direction, the Y direction, and the θZ direction by a driving mechanism (not shown). The center of the pattern area is the optical axis A of the projection optical system PL.
The mask M can be positioned so as to pass through X.

The projection optical system PL projects the pattern of the mask M illuminated by the exposure light EL onto the wafer W and comprises a plurality of optical elements (lenses) L1, L2 and L3. The plurality of optical elements L1 to L3 are arranged and sealed in the lens barrel PK. The lens barrel PK surrounds the optical path of the exposure light EL.

Of the plurality of optical elements forming the projection optical system PL, the optical element L2 is a binary optical element (BOE) as a diffusing member. The binary optical element (diffusing member) L2 is
This is for correcting the axial chromatic aberration of the optical system by diffracting light, and its surface has a stepped shape in cross section as shown in FIG. 2, and the exposure light EL irradiates this exposure light. The light EL is diffused.

Each optical element L1, L2 of the projection optical system PL
Each L3 is supported by the lens barrel PK via a holding member. At this time, the lens barrel PK, the holding member, and the optical element L1
Each of L3 to L3 is fixed to each other by a mechanical holding structure (mechanical clamp) that does not use an adhesive as much as possible.
The projection optical system PL in the present embodiment is, for example, a reduction optical system having a projection magnification of 1/4 or 1/5, and the pattern formed on the mask M is reduced to a shot area on the wafer W by the projection optical system PL. Projected.

The wafer W is placed in the wafer chamber 20. The wafer chamber 20 includes a wafer holder WH that holds the wafer W by vacuum suction. This wafer chamber 20
Is covered with a partition WK that is joined to the lens barrel PK without any gap. A transmission window 9 is arranged between the inner space of the lens barrel PK and the wafer chamber 20. Further, an opening for loading / unloading the wafer W and an opening / closing door (not shown) for opening / closing the opening are provided on the side wall of the partition WK. By closing the opening / closing door, the wafer chamber 20
Is designed to be hermetically sealed. The wafer holder WH is
It is supported by wafer stage WST. Wafer stage WST is movable in XY and Z directions. The position of wafer stage WST is measured by a laser interferometer (not shown), and is controlled based on the measurement result.

As shown in FIGS. 1 and 2, a titanium oxide thin film T is provided as a photocatalyst on the inner wall of the lens barrel PK. Titanium oxide is light from a binary optical element (diffused light)
Is emitted, the contaminants existing in the optical path space LS are photodecomposed. Here, the contaminants present in the optical path space are organic compounds such as hydrocarbons, carboxylic acid compounds, and acrylamides, which contaminate the surface of the optical element (lens) and make it cloudy. Optical path space L
Contaminants existing in S are, for example, processing oil remaining in each member at the time of manufacturing and processing, decomposition products due to photoreaction of resist, emission materials from processes such as coating, development, baking, cleaning, and wall materials. Due to volatile substances from

The titanium oxide thin film T is provided on the inner wall of the lens barrel PK by coating or vapor deposition.
The film thickness is set to 100 μm. Titanium oxide activates a part of oxygen inside the lens barrel PK (optical path space LS) with the energy of ultraviolet rays, especially far ultraviolet rays. The activated oxygen reacts with pollutants (organic substances) attached to the surface of the optical element inside the lens barrel PK, and CO ₂ and CO having high vapor pressure are emitted.
And so on. At the same time, H ₂ O is also generated.

Titanium oxide absorbs ultraviolet rays, especially far ultraviolet rays, and exerts an effect as an optical semiconductor. Representative actions of the effect as an optical semiconductor include an antistatic action due to electroconductivity, a photodecomposition action as a photocatalyst, a reduction in contact angle with water (decrease in adsorption amount), and an antibacterial action. Titanium oxide has a high refractive index as an optical property.

Further, since titanium oxide can absorb light in the ultraviolet region, the titanium oxide thin film T provided on the inner wall of the lens barrel PK is flared by the binary optical element L2 (scattered light).
Can be absorbed. Therefore, by providing the titanium oxide thin film T, generation of flare light unnecessary for the exposure process is prevented.

The exposure apparatus EX in the present embodiment uses the mask M by the exposure light EL in the inter-shot stepping operation of moving the wafer stage WST so as to sequentially position each shot area on the wafer W at the projection position. And an exposure operation for transferring the image of the pattern formed on the mask M to the shot area on the wafer W are repeated.

The internal space (closed space) formed in each of the illumination system housing IK of the illumination optical system 2, the mask chamber 10, the lens barrel PK of the projection optical system PL, and the wafer chamber 20 allows the gas to flow to the outside. Is formed, and an optical path space LS of the exposure light EL that is emitted from the light source 1 and is irradiated onto the wafer W is formed.

By the way, when the light having a wavelength in the vacuum ultraviolet region is used as the exposure light EL, in the optical path space LS, not only the pollutants mentioned above but also light in such a wavelength band such as oxygen, water vapor, hydrocarbon type gas, etc. On the other hand, it is necessary to reduce the concentration of a gas having a strong absorption characteristic (hereinafter, referred to as "absorptive substance"). For this reason, the optical path space LS is subjected to an operation of reducing the concentration of the light absorbing substance existing therein as needed by a gas replacement device (not shown). At this time, the optical path space LS is made of gas such as nitrogen, helium, argon, neon, krypton or the like, or a mixed gas thereof (hereinafter referred to as “inert gas”), which has a property of having a low absorption property for light in the vacuum ultraviolet region. It is filled.

For example, the gas replacement device (not shown) may be installed in the illumination system housing IK with respect to the interior of the illumination system housing IK.
The inert gas is supplied from the air supply port 11 provided on one end side of the light source 1 side, and the gas inside the illumination system housing IK is supplied from the exhaust port 12 provided on the other end side farthest from the air supply port 11. Exhaust. Similarly, the gas replacement device supplies an inert gas to the inside of the mask chamber 10 from the air supply port 13 and exhausts the gas inside the mask chamber 10 from the exhaust port 14 to the inside of the lens barrel PK. While supplying the inert gas from the air supply port 15, the gas inside the lens barrel PK is exhausted from the exhaust port 16, and the inert gas is supplied to the inside of the wafer chamber 20 from the air supply port 17 and exhausted. The gas inside the wafer chamber 20 is exhausted through the port 18. In addition, air supply port 1
1, 13, 15, 17 and exhaust ports 12, 14, 16, 1
Each of 8 is provided with a valve. By adjusting these valves, the supply amount of the inert gas per unit time and the gas exhaust amount from the optical path space LS are adjusted. A HEPA filter (High Efficiency Particulate) is provided in each of the exhaust pipes (not shown) connecting the exhaust ports 12, 14, 16, and 18 to the gas replacement device.
Air Filter) or ULPA filter (Ultra Low Pe)
An air filter that removes dust (particles) such as a netration air filter) and a chemical filter that removes the light-absorbing substance such as oxygen described above are arranged. Similarly, an air filter and a chemical filter are also arranged in each of the air supply pipes (not shown) that connect each of the air supply ports 11, 13, 15, 17 and the gas replacement device.

The gas replacement device is a projection housing I.
It is possible to independently adjust the concentration of the light-absorbing substance in K, in the mask chamber 10, in the lens barrel PK, and in the wafer chamber 20, and it is possible to control the light-absorbing substance concentration to be different according to the optical path length and the disturbance frequency. .

The illumination system housing IK, the partition MK,
The lens barrel PK, the partition WK, and the like use a material such as stainless steel (SUS) to reduce the surface roughness by a treatment such as polishing, so that degassing is suppressed.

Next, the exposure apparatus EX having the above-mentioned structure
An exposure method for exposing the pattern of the mask M onto the wafer W will be described. The exposure light EL from the projection optical system IL illuminates the mask M held by the mask holder MH. The pattern of the mask M illuminated with the exposure light EL is transferred onto the wafer W held by the wafer holder MH via the projection optical system PL.

At this time, the exposure light EL which has passed through the mask M
Enters the binary optical element L2 arranged in the lens barrel PK in the optical path space LS of the exposure light EL. As shown in FIG. 2, the exposure light E incident on the binary optical element L2
Part of L passes through the binary optical element L2, and the rest becomes diffused light. The diffused light illuminates the titanium oxide thin film T provided on the inner wall of the barrel PK. Titanium oxide thin film T
Is irradiated with diffused light based on the exposure light EL that is vacuum ultraviolet light, and thereby undergoes a photocatalytic reaction to photolyze the contaminants existing in the optical path space LS. In this way, the exposure light EL
A binary optical element L2 as a diffusing member is arranged on the optical path of the titanium oxide thin film on the inner wall of the barrel PK as a position in the optical path space LS of the exposure light EL to which the diffused light from the binary optical element L2 is irradiated. By providing T and irradiating the titanium oxide thin film T with diffused light (exposure light EL), contaminants existing in the optical path space LS are photodecomposed. On the other hand, the exposure light EL that has passed through the binary optical element L2 reaches the wafer W, and the pattern of the mask M is transferred to the wafer W.

While the pattern of the mask M is being transferred onto the wafer W by the exposure light EL, the titanium oxide thin film T provided on the inner wall of the lens barrel PK is irradiated with the diffused light from the binary optical element L2. Meanwhile, the gas replacement device supplies the inert gas into the lens barrel PK and exhausts the gas inside the lens barrel PK. Therefore, the photodecomposition product of the pollutant photodecomposed by irradiating the titanium oxide thin film T with diffused light is exhausted to the outside from the lens barrel PK by the gas replacement device. In this way, the contaminants existing in the lens barrel PK (optical path space LS) are reduced by being decomposed photolytically and then discharged to the outside. At this time, the gas replacement device also reduces the light-absorbing substance existing in the optical path space LS.

As described above, the titanium oxide thin film T capable of photolyzing the contaminants existing in the optical path space LS is provided at the position where the diffused light diffused by the binary optical element L2 as the diffusing member is irradiated. The optical path space LS
A photocatalytic reaction occurs in, and the pollutants existing in the optical path space LS can be easily and efficiently decomposed based on the photocatalytic reaction. Therefore, it is possible to suppress the fogging of each optical element that constitutes the projection optical system PL based on the contaminants and remove the fogging.
An accurate exposure process can be performed.

Further, the binary optical element L2 forming a part of the projection optical system PL is used as a diffusing member for diffusing the exposed exposure light EL and irradiating the titanium oxide thin film T with this diffused light. , The pattern of the mask M on the wafer W
It is possible to simultaneously perform the exposure process of exposing to light and the decomposition process of the contaminants (organic substances) existing in the optical path space LS.
Therefore, the optical path space LS always maintains a desired cleanliness, and the optical performance of the optical system is stabilized for a long period of time.

By the way, as described above, titanium oxide (photocatalyst) decomposes pollutants by activating oxygen. Therefore, while supplying a small amount of oxygen to the optical path space LS, the diffused light based on the exposure light EL is supplied to the titanium oxide thin film T.
By irradiating the same, the contaminant decomposition process can be efficiently performed. For example, the gas replacement device uses a mixed gas of an inert gas and a small amount of oxygen in the optical path space LS (lens barrel PK).
May be supplied to. On the other hand, even if oxygen is not positively supplied to the optical path space LS, the hydrocarbon, which is a contaminant, contains oxygen molecules in the molecule, so that the oxygen reacts to generate activated oxygen.

Next, a second embodiment of the exposure apparatus of the present invention will be described with reference to FIG. In the following description, the same or equivalent components as those of the above-described first embodiment will be designated by the same reference numerals, and the description thereof will be simplified or omitted.

As shown in FIG. 3, a diffusing plate Ma as a diffusing member is arranged on the mask holder MH in the optical path space LS of the exposure light EL. That is, in this embodiment, the diffusion plate Ma, which is a diffusion member, is arranged in the mask holder MH in which the mask (first surface) M is to be arranged.

The diffusion plate Ma diffuses the exposure light EL from the illumination optical system IL while passing it. That is, the diffusion plate Ma
Is a transmissive diffusion plate that diffuses the exposure light EL irradiated by the illumination optical system IL on the downstream side of the optical path.

On the inner wall of the lens barrel PK, a titanium oxide thin film T is provided at a position where the diffused light based on the exposure light EL from the diffuser plate Ma is irradiated. The titanium oxide thin film T is irradiated with diffused light based on the exposure light EL to photolyze the contaminants existing in the optical path space LS. The photolysis products obtained by photolyzing the pollutants are exhausted to the outside from the lens barrel PK by the gas replacement device. Thus, the lens barrel P
The contaminants existing in the K (optical path space LS) are photolyzed and then discharged to the outside to be reduced. Then, when the contaminants in the optical path space LS are reduced (when the cloudiness on the surface of the optical element is removed), the diffusion plate Ma is unloaded from the mask holder MH, the mask M is loaded on the mask holder MH, and the mask M is loaded. Exposure process is performed.

As described above, the diffusing member for diffusing the exposure light EL from the illumination optical system IL may be the diffusing plate Ma arranged at the position where the mask M should be arranged in the exposure processing.

In the second embodiment, the pollutant decomposition process using the diffusion plate Ma is performed every predetermined time interval or every predetermined number of wafers to be processed. When the contaminant decomposition process using the diffusion plate Ma is performed after the exposure process using the mask M, the mask M is unloaded and the diffusion plate Ma is loaded on the mask holder MH so that it exists in the optical path space LS. Perform photodecomposition work of pollutants.

Alternatively, for example, a detector capable of detecting the contaminant concentration in the optical path space LS without performing the contaminant decomposition processing using the diffusion plate Ma at predetermined time intervals or at intervals of a predetermined number of wafers to be processed. Provided, the optical path space L
When the pollutant concentration in S exceeds a predetermined value, the pollutant decomposition process by the diffusion plate Ma may be performed. Alternatively, an illuminance sensor may be provided on wafer stage WST, and when the illuminance sensor detects uneven illuminance due to contaminants attached to the optical elements, the contaminant decomposition process by diffusion plate Ma may be performed.

In the second embodiment, the pollutant decomposition process and the exposure process cannot be performed at the same time, but the type of the diffusion member can be easily exchanged. In this case, by exchanging the diffusion plates Ma having different diffusion angles, it is possible to irradiate the diffused light to an arbitrary position in the lens barrel PK. For example, a diffusion plate Ma having a large diffusion angle
Is placed on the mask holder MH, the diffused light from the diffuser plate Ma is located at the upper position (lens L) on the inner wall of the lens barrel PL.
1) is irradiated. In this case, the pollutants existing in the upper position inside the lens barrel PK and the pollutants adhering to the lens L1 can be mainly decomposed. On the other hand, when the diffusion plate Ma having a small diffusion angle is arranged in the mask holder MH, the diffused light from the diffusion plate Ma irradiates a lower position (in the vicinity of the lens L3) on the inner wall of the lens barrel PK, and this position is positioned at this position. The existing pollutants can be decomposed intensively.
As described above, by arbitrarily setting the diffusion angle of the diffusion plate Ma, the work of removing the contaminants from any position of the lens barrel PK or any optical element of a plurality of arranged optical elements is focused. be able to.

The insertion of the diffusion plate Ma into the optical path space LS (that is, loading on the mask holder MH) is performed by the wafer W.
You may go at the time of exchange. This makes it possible to perform light cleaning while reducing the decrease in throughput.
Irradiating the wafer W with unnecessary scattered light is also eliminated.

In the second embodiment, titanium oxide (photocatalyst) may be applied to the diffusion plate Ma itself.

The diffusing member is not limited to the binary optical element L2 and the diffusing plate Ma as shown in the first and second embodiments. For example, a reflection type diffusion plate is provided on the wafer holder WH on which the wafer (second surface) W is arranged, the exposure type light EL is reflected and diffused by this reflection type diffusion plate, and the oxidation is provided on the inner wall of the lens barrel PK. The titanium thin film T may be irradiated with diffused light.

Alternatively, a diffusion member (reflection type diffusion plate) is provided in a part of wafer stage WST, and optical path space LS is provided.
The wafer stage W is arranged so that the diffusing member is arranged in the projection area of the projection optical system PL when decomposing contaminants inside the wafer.
It is also possible to move ST and irradiate this diffusion member with the exposure light EL. The portion on the wafer stage WST where the diffusion member is provided may be the wafer mounting surface or a portion other than the wafer mounting surface. Also, the wafer stage WS
Titanium oxide may be applied to the diffusion member provided at T. In the contaminant decomposition process using the diffusion member (or titanium oxide thin film) provided on wafer stage WST, the exposure process for the first wafer is completed, and the first wafer is unloaded from wafer stage WST. After that, it can be performed until the second wafer is loaded on wafer stage WST. When the diffusion member is provided on the wafer stage WST other than the wafer mounting surface, the diffusion member is moved to the projection area of the projection optical system PL while holding the wafer W, and the exposure light EL is applied to the diffusion member. Can be irradiated. Then, when the pollutant decomposition processing using this diffusion member is completed, wafer stage WST is moved so that wafer W is arranged within the projection area of projection optical system PL.

Further, a diffusing member (transmissive diffusing plate) is provided on a part of a mask stage (not shown) that supports the mask holder MH.
Is provided, the mask stage is moved so that the diffusion member is arranged in the illumination region of the illumination optical system IL when the contaminants are decomposed in the optical path space LS, and the diffusion member is irradiated with the exposure light EL. You may do it. Alternatively, titanium oxide may be applied to the diffusion member provided on the mask stage. When the diffusion member (or the titanium oxide thin film) provided on the mask stage is used, the contaminant decomposition process is completed by the exposure process using the first mask, and the first mask is unloaded from the mask stage. After that, it can be performed before the second mask is loaded on the mask stage. When the diffusion member is provided on the mask stage other than the mask mounting surface, the diffusion member is moved to the illumination area of the illumination optical system IL while holding the mask M, and the exposure light EL is applied to the diffusion member. Can be illuminated. Then, when the pollutant decomposition process using the diffusion member is completed, the mask stage is moved so that the mask M is arranged in the illumination area of the illumination optical system IL.

It is not necessary to apply the titanium oxide thin film T to the entire inner wall of the lens barrel PK, and for example, the binary optical element L2 is used.
In the vicinity of the optical path, specifically, in the inner wall of the lens barrel PK in which the binary optical element L2 is arranged, a part of the optical path upstream side, a part of the optical path downstream side, or a part of both the optical path upstream and downstream sides. It may be provided. Also,
When the diffusing member is the diffusing plate Ma arranged in the mask holder MH, it may be provided on the inner wall of the lens barrel PK near the optical path downstream side of the diffusing plate Ma. That is, the titanium oxide thin film T is locally provided only on the portion irradiated with the diffused light from the diffusing member.

In each of the above embodiments, the titanium oxide thin film T is provided on the inner wall of the lens barrel PK.
And a supporting member that connects the lenses L1 to L3 (see FIGS. 2 and 3).
The titanium oxide thin film T may be provided on the reference numeral J).

In each of the above embodiments, the titanium oxide thin film T is provided on the inner wall of the lens barrel PK surrounding the optical path of the projection optical system PL, but the illumination system housing (lens barrel) IK surrounding the optical path of the illumination optical system IL. It may be provided on the inner wall of the. in this case,
A diffusing member is provided in the illumination optical system IL. Further, the titanium oxide thin film T can be provided on the inner walls of the partition walls MK and WK. That is, the photocatalyst and the diffusing member that irradiates the photocatalyst with diffused light may be provided anywhere as long as it is the optical path space LS of the exposure light EL.

Although titanium oxide is used as a photocatalyst in each of the above-mentioned embodiments, ZrO ₂ , HfO ₂ , and Ti are used.
O ₂ and mixtures of these substances may also be used.

A support device is provided for holding the diffusing member and supporting the held diffusing member in the optical path of the exposure light EL so that the diffusing member can be put into and out of the optical path space LS when the contaminant is decomposed. Use the device to expose the diffusion member to the exposure light E
It may be arranged on the optical path of L and the exposure light EL may be irradiated to this diffusion member.

In each of the above-described embodiments, the titanium oxide thin film T is provided in at least a part of the optical path space LS of the exposure light EL, and the diffusion member is irradiated with the exposure light EL to diffuse the diffused light from the diffusion member. For example, an oscillating device capable of oscillating the optical axis of the exposure light EL is provided, and the optical path of the exposure light EL is oscillated by using this oscillating device, and is provided on the inner wall of the barrel PK. Exposure light E for the titanium oxide thin film T
You may make it irradiate L directly. Alternatively, a diffusing member may be arranged on the optical path of the exposure light EL, and the angle of incidence of the exposure light EL on the diffusing member may be changed by the rocking device to change the direction of the diffusing light from the diffusing member. Good. However, when the diffused light (light unnecessary for exposure, in other words, flare light) is increased by providing the diffusing member in the projection optical system PL, and the exposure accuracy of the circuit pattern is reduced, the optical path space LS, Optical path space L
It is desirable to provide a field stop between the diffusion member and the wafer W in S.

In each of the above embodiments, the light applied to the diffusing member is the light flux emitted from the exposure light source 1,
A second light source different from the exposure light source 1 is provided, and the second light source is provided.
The diffusing member may be irradiated with light from the light source.
It is also possible to provide the second light source with the swinging device as described above.

As the exposure apparatus EX of the above embodiment, in addition to the step-and-repeat type exposure apparatus which exposes the pattern of the mask M while the mask M and the wafer W are stationary, the wafer W is sequentially moved stepwise. It can also be applied to a scanning type exposure apparatus that exposes the pattern of the mask M by synchronously moving the mask M and the wafer W. In the scanning type exposure apparatus, when the diffusion plate is placed on the mask holder MH, the diffusion plate is scanned,
Scattered light with averaged light intensity can be generated, and higher reactivity with the photocatalyst can be expected.

The exposure apparatus EX is widely used as an exposure apparatus for manufacturing a semiconductor, an exposure apparatus for a liquid crystal that exposes a liquid crystal display element pattern on a rectangular glass plate, an exposure apparatus for producing a thin film magnetic head, and the like. Can be suitable.

The light source 1 of the exposure apparatus EX of this embodiment uses the bright line (g line (436n
m), h line (404.7 nm), i line (365n)
m)), KrF excimer laser (248 nm), ArF
An excimer laser (193 nm) or the like can also be used. Further, a high frequency wave such as a YAG laser or a semiconductor laser may be used.

The magnification of the projection optical system PL is not limited to a reduction system, and may be a unity magnification system or an enlargement system.

As the projection optical system PL, a material that transmits far ultraviolet rays such as quartz or fluorite is used as a glass material when far ultraviolet rays such as an excimer laser is used, and a catadioptric system when F ₂ laser is used. A refraction-type optical system is used (the mask M also uses a reflection type).

When a linear motor is used for wafer stage WST or a mask stage, either an air levitation type using an air bearing or a magnetic levitation type using Lorentz force or reactance force may be used. Further, the stage may be of a type that moves along a guide, or may be a guideless type that does not have a guide.

When a plane motor is used as a drive device for the stage, one of the magnet unit (permanent magnet) and the armature unit is connected to the stage, and the other of the magnet unit and the armature unit is on the moving surface side of the stage. It may be provided on the (base).

The reaction force generated by the movement of wafer stage WST is mechanically fixed to the floor (ground) by using a frame member, as described in JP-A-8-166475.
You may let me escape. The present invention can be applied to an exposure apparatus having such a structure.

The reaction force generated by the movement of the mask stage may be mechanically released to the floor (ground) by using a frame member, as described in JP-A-8-330224. The present invention can be applied to an exposure apparatus having such a structure.

As described above, the exposure apparatus according to the embodiment of the present application uses various subsystems including the constituent elements recited in the claims of the present application, with predetermined mechanical accuracy, electrical accuracy, and
It is manufactured by assembling so as to maintain optical accuracy. Before and after this assembly, adjustments to achieve optical precision for various optical systems, adjustments to achieve mechanical precision for various mechanical systems, and various electrical systems to ensure these various types of precision are made. Are adjusted to achieve electrical accuracy. The process of assembling the exposure apparatus from the various subsystems includes mechanical connection, electrical circuit wiring connection, air pressure circuit pipe connection, and the like between the various subsystems. It goes without saying that there is an individual assembly process for each subsystem before the assembly process from these various subsystems to the exposure apparatus. When the process of assembling the various subsystems into the exposure apparatus is completed, comprehensive adjustment is performed to ensure various accuracies of the exposure apparatus as a whole. It is desirable that the exposure apparatus be manufactured in a clean room where the temperature and cleanliness are controlled.

As shown in FIG. 4, the semiconductor device has a step 201 for designing the function and performance of the device, a step 202 for producing a mask (reticle) based on this design step, and a substrate (wafer) as a base material. Manufacturing step 203, substrate processing step 20 of exposing the mask pattern onto the substrate by the exposure apparatus of the above-described embodiment
4, device assembly step (including dicing step, bonding step, packaging step) 205, inspection step 206, etc.

[0065]

As described above, according to the exposure method of the first aspect and the exposure apparatus of the sixth aspect, the contamination existing in the optical path space at the position where the light diffused by the diffusing member is irradiated. By providing a photocatalyst that can photolyze a substance,
By the photocatalytic reaction of the photocatalyst, contaminants existing in the optical path space can be easily and efficiently decomposed and reduced. Therefore, it is possible to perform the exposure process with high accuracy and stability.

According to the exposure method of the second aspect, since the diffusing member is the binary optical element arranged on the optical path of the exposure light, the photolysis processing and the exposure processing of the contaminants existing in the optical path space are performed simultaneously. It can be carried out. Therefore, since the optical path space is always maintained at a desired cleanliness, the optical characteristics of the optical system can be stabilized for a long period of time.

According to the exposure method of the third aspect, since the diffusion member is the diffusion plate arranged on the first surface, the contaminant decomposition process can be performed with a simple structure.

According to the exposure method of the fourth aspect, since the photocatalyst is applied to the inner wall of the lens barrel surrounding the optical path of the exposure light, it is possible to effectively reduce the contaminants in the optical path space. it can.

According to the fifth aspect of the exposure method, since the photocatalyst is titanium oxide, when exposed to the exposure light, the activated oxygen can effectively photodecompose the contaminants.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a first embodiment of an exposure apparatus of the present invention.

FIG. 2 is an enlarged view of a main part showing the vicinity of the binary optical element in FIG.

FIG. 3 is an enlarged view of a main part of the exposure apparatus according to the second embodiment of the present invention, showing the vicinity of the diffusion plate.

FIG. 4 is a flowchart showing an example of a manufacturing process of a semiconductor device.

[Explanation of symbols]

1 light source EL exposure light EX exposure equipment L2 Binary optical element (diffusing member) M mask (first surface) Ma diffusion plate (diffusion member) PK barrel T Titanium oxide thin film (photocatalyst) W wafer (W)

Claims (6)

[Claims] 1. A pattern on the first surface is formed into a second pattern by exposure light.
In an exposure method for exposing a surface, while disposing a diffusing member that diffuses light on the optical path of the exposure light, in an optical path space through which the exposure light passes, at a position where light from the diffusing member is irradiated, A photocatalyst capable of photolyzing contaminants existing in the optical path space is provided, and while the diffused light generated by irradiating the diffusion member with light is applied to the photocatalyst, the pattern on the first surface is An exposure method comprising exposing the second surface. 2. The exposure method according to claim 1, wherein the diffusing member is a binary optical element arranged on the optical path. 3. The exposure method according to claim 1, wherein the diffusion member is a diffusion plate disposed on the first surface. 4. The exposure method according to claim 1, wherein the photocatalyst is applied to an inner wall of a lens barrel surrounding an optical path of the exposure light. 5. The exposure method according to claim 1, wherein the photocatalyst is titanium oxide. 6. A second pattern is formed on the first surface by exposure light.
In an exposure apparatus that exposes a surface, a diffusing member that is arranged on the optical path of the exposing light and diffuses the light, and an optical path space through which the exposing light passes is provided at a position where the light from the diffusing member is irradiated. And a photocatalyst capable of photodecomposing contaminants existing in the optical path space.