JP2011204864A - Reflection type mask, aligner, exposure method, and device manufacturing method - Google Patents

Abstract

Provided are a reflective mask, an exposure apparatus, an exposure method, and a device manufacturing method capable of effectively reducing contaminants.
A reflection type mask (R) having a pattern area (Ra) provided with a reflection pattern, wherein incident light is reflected or scattered in a direction different from a reflection direction in which the pattern area (Ra) is reflected. It has a non-pattern area (Rb).
[Selection] Figure 2

Description

  The present invention relates to a reflective mask, an exposure apparatus, an exposure method, and a device manufacturing method.

  In recent years, with the progress of miniaturization of semiconductor integrated circuit elements, in order to improve the resolution of an optical system limited by the diffraction limit of light, EUV (Extreme) having a shorter wavelength is used instead of ultraviolet light as exposure light. Ultra Violet (ultraviolet) light is attracting attention. In this type of exposure apparatus, a reflection type optical integrator, a reflection type mask, and a reflection type projection optical system are used (for example, refer to Patent Document 1). In a reflective mask, a reflective layer (for example, a multilayer reflective layer) is formed on a mask substrate, and a light shielding portion (light absorber layer) having a shape corresponding to the pattern shape is formed on the reflective layer (for example, Patent Document 2).

In the exposure apparatus, for example, contaminants such as organic substances may be generated from members or the like disposed in the exposure apparatus. Among contaminants generated in the exposure apparatus, substances having a high boiling point easily adhere to the surfaces of various members in the exposure apparatus. When the contaminants adhere to the reflecting surface of the optical element, the reflectance of the optical element is lowered, and the exposure amount to the substrate such as a wafer is reduced, resulting in a problem that the throughput is lowered. In particular, EUV light causes carbon-based molecules floating in the vicinity thereof to adhere to the surface of the optical element. In addition, contaminants attached to members other than the optical element may eventually adhere to the optical element while repeatedly attaching to and detaching from members other than the optical element.
For this reason, conventionally, measures such as increasing the degree of vacuum in the exposure apparatus have been taken in order to reduce the carbon-based molecules adhering to the optical element.

US Pat. No. 6,452,661 JP-A-8-17716

However, the above-described conventional technology has the following problems.
As the degree of vacuum, generally, the carbon-based molecular partial pressure (integrated value) is required to be 10 ⁻⁷ Pa or less. However, even at such a high degree of vacuum, it is difficult to completely remove the carbon-based molecules, and it has been desired to develop a technique for effectively reducing pollutants.

  Therefore, an object of the present invention is to provide a reflective mask, an exposure apparatus, an exposure method, and a device manufacturing method that can effectively reduce contaminants.

  According to the first aspect of the present invention, there is provided a reflective mask having a pattern area provided with a reflection pattern, which reflects or scatters incident light in a direction different from a reflection direction reflected by the pattern area. A reflective mask having a pattern region is provided.

  According to a second aspect of the present invention, there is provided an exposure apparatus for forming a pattern provided on a reflective mask on a photosensitive substrate, the illumination optical system for irradiating the reflective mask with exposure light, and the pattern. The projection optical system that exposes the photosensitive substrate with the reflected exposure light, and at least a part of the exposure light is reflected or scattered to the cleaning target portion different from the photosensitive substrate, and the reflected or scattered An exposure apparatus having a cleaning optical unit that irradiates at least part of exposure light is provided.

  According to a third aspect of the present invention, there is provided an exposure method for forming a pattern provided on a reflective mask on a photosensitive substrate, wherein the pattern region is irradiated with the exposure light using the reflective mask. There is provided an exposure method including exposing the photosensitive substrate and irradiating the non-pattern area with the exposure light to photoclean a portion to be cleaned different from the photosensitive substrate.

  According to a fourth aspect of the present invention, there is provided an exposure method for forming a pattern provided on a reflective mask on a photosensitive substrate, wherein the exposure mask is used to irradiate the reflective mask with the exposure light. There is provided an exposure method including exposing the photosensitive substrate and irradiating the cleaning optical unit with the exposure light to photoclean the target object.

  According to a fifth aspect of the present invention, there is provided a device manufacturing method including exposing a photosensitive substrate using the above exposure apparatus and processing the exposed photosensitive substrate.

  According to the aspect of the present invention, the generation of contaminants can be effectively suppressed.

It is a typical sectional view showing an example of an exposure apparatus concerning an embodiment. It is a typical perspective view which shows an example of the reticle which concerns on embodiment. FIG. 3 is a schematic partial cross-sectional view of the reticle shown in FIG. 2. It is a typical perspective view which shows an example of the wafer which concerns on another embodiment. It is the typical sectional view to which the principal part of the exposure apparatus concerning another embodiment was expanded. It is a flowchart which shows an example of the device manufacturing process which concerns on embodiment. It is a flowchart which shows an example of the wafer process shown in FIG.

  Embodiments of a reflective mask, an exposure apparatus, an exposure method, and a device manufacturing method according to the present invention will be described below with reference to FIGS.

FIG. 1 is a sectional view schematically showing the overall configuration of the exposure apparatus of the present embodiment.
An exposure apparatus 100 shown in FIG. 1 is an EUV exposure apparatus that uses EUV light (Extreme Ultraviolet Light) having a wavelength of 100 nm or less. The wavelength of the EUV light used in the exposure apparatus 100 may be in the range of about 3 to 50 nm, for example. The exposure apparatus 100 of the present embodiment uses EUV light having a wavelength of 11 nm to 14 nm.

  In the following, in order to distinguish between the EUV light used for exposure and the EUV light used for cleaning, the EUV light used for exposure is referred to as “exposure light EL”, and the EUV light used for cleaning is referred to as “cleaning light EC. ". Note that the exposure light EL and the cleaning light EC may be EUV light having the same wavelength or light having different wavelengths. The cleaning light EC may have a wavelength of, for example, 250 nm or less, and more preferably, ultraviolet light having a wavelength of 190 nm or less is used.

  As shown in FIG. 1, the exposure apparatus 100 mainly includes a vacuum chamber (housing) 1, a reticle holding unit 4, a wafer holding unit 5, and a laser plasma light source at least partially disposed inside the vacuum chamber 1. 10, an illumination optical system ILS, a projection optical system PO, and a main control system 31.

The vacuum chamber 1 is an airtight container isolated from an external space by a partition wall. A plurality of sub chambers (not shown) are provided inside the vacuum chamber 1 in order to further increase the degree of vacuum of the optical path of the exposure light EL. The pressure inside the vacuum chamber 1 is, for example, about 10 ⁻⁵ Pa, and the pressure inside the sub-chamber accommodating the projection optical system PO inside the vacuum chamber 1 is, for example, about 10 ⁻⁵ to 10 ^−8. It is about Pa. A vacuum pump 32A is connected to the vacuum chamber 1 through an exhaust pipe 32Aa, and a gas supply unit 32B that supplies an oxidizing gas or a reducing gas is connected through an air supply pipe 32Ba.

In order to prevent the exposure light EL from being absorbed by the gas, the vacuum pump 32A exhausts the gas inside the vacuum chamber 1 through the exhaust pipe 32Aa and maintains the inside of the vacuum chamber 1 at a predetermined degree of vacuum.
When the exposure apparatus 100 performs cleaning with the cleaning light EC (light cleaning), the gas supply unit 32B supplies an oxidizing gas or a reducing gas in the vicinity of a portion to be cleaned (cleaning target portion). For example, O ₂ , O ₃ , H ₂ O, H ₂ O ₂ , CO, and NO can be used as the oxidizing gas or reducing gas supplied by the gas supply unit 32B. These gases may be used as a mixture or alone.

The laser plasma light source 10 is a gas jet cluster type light source that generates exposure light EL. The laser plasma light source 10 includes a laser light source (not shown) that emits exposure light EL, a condenser lens 12, a nozzle 14, and a condenser mirror 13.
The condensing lens 12 condenses the exposure light EL irradiated from a laser light source (not shown) through the window member 15 of the vacuum chamber 1 inside the condensing mirror 13.
The condensing mirror 13 has an elliptical spherical reflecting surface, and condenses the EUV light generated inside the reflecting surface by being reflected by the reflecting surface.
The nozzle 14 supplies a gaseous target such as xenon or krypton, or a target such as Sn (tin).

The illumination optical system ILS includes a plurality of mirrors that reflect the exposure light EL (cleaning light EC) emitted from the laser plasma light source 10, and exposes the exposure light EL on the reticle (reflection mask) R held on the reticle stage RST. This is an optical system for irradiating.
The illumination optical system ILS includes an optical integrator and a condenser optical system for making the illuminance distribution of the exposure light EL uniform, and an aperture stop AS.

The optical integrator is composed of a pair of fly-eye optical systems 22 and 23. The fly's eye optical system 23 has a number of reflecting mirror elements. Further, the surface in the vicinity of the reflecting surface of the fly-eye optical system 23 is the pupil surface of the illumination optical system ILS, and the aperture stop AS is disposed at this pupil surface or at a position near this pupil surface.
The condenser optical system includes a curved mirror 24 and a concave mirror 25, reflects the exposure light EL reflected by a number of reflecting mirror elements of the fly-eye optical system 23, and irradiates it in a superimposed manner on the pattern area of the reticle R.
Several aperture stops AS having differently shaped apertures are prepared, and are provided so as to be replaceable by a driving device (not shown).

  The reticle R has a pattern area in which a reflection pattern corresponding to, for example, a circuit pattern of an electronic circuit is provided on the surface irradiated with the exposure light EL. That is, the reticle R of the present embodiment is a reflective reticle (reflective mask).

Blind plates 26A and 26B are arranged on the side of the reticle R that is irradiated with the exposure light EL. The blind plates 26A and 26B are disposed, for example, in the vicinity of a conjugate plane with the pattern region in the illumination optical system ILS.
Further, an optical system for measuring the position in the Z direction (Z position) of the reticle surface by irradiating, for example, measurement light obliquely to the pattern area of the reticle R on the side of the reticle R irradiated with the exposure light EL. A reticle autofocus system (not shown) is arranged.

The reticle holding unit 4 is a drive system that holds and moves the reticle R. The reticle holding unit 4 includes a reticle stage RST, a reticle holder (mask holder) RH, a partition 8, and a driving device (not shown).
The reticle holder RH is disposed on the reticle stage RST and is adapted to attract and hold the reticle R by, for example, an electrostatic chuck.

The partition 8 is provided so as to cover the reticle stage RST exposed from the partition wall of the vacuum chamber 1. The interior of the partition 8 is maintained at an atmospheric pressure between the atmospheric pressure and the atmospheric pressure inside the vacuum chamber 1 by a vacuum pump (not shown).
A drive device (not shown) that drives the reticle stage RST is configured by, for example, a magnetically levitated two-dimensional linear actuator.

The projection optical system PO includes a plurality of mirrors that reflect EUV light reflected by the reflection pattern of the reticle R, and a wafer (photosensitive substrate) on which an image of the pattern formed on the reticle R is coated with a resist (photosensitive material). ) An optical system that projects onto W.
The projection optical system PO is configured, for example, by holding six mirrors M1 to M6 with a lens barrel (not shown). As an example, the mirrors M1, M2, M4, and M6 are concave mirrors, and the other mirrors M3 and M5 are convex mirrors.
The projection optical system PO is a non-telecentric reflection system on the reticle R (object) side and a telecentric reflection system on the wafer W (image) side, and the projection magnification is, for example, a reduction magnification of 1/4.

The wafer holding unit 5 is a drive system that holds and moves the wafer W. Wafer holding unit 5 includes wafer stage WST that holds the wafer, a driving device (not shown) that drives wafer stage WST, an aerial image measurement system 29, and partition 7.
A drive device (not shown) for driving wafer stage WST is constituted by, for example, a magnetically levitated two-dimensional linear actuator.
The aerial image measurement system 29 is installed in the vicinity of the position where the wafer W is held on the wafer stage WST, and detects an image of the alignment mark of the reticle R, for example.

  The partition 7 is arranged so as to cover the wafer W and the wafer stage WST so that the gas generated from the resist on the wafer W during exposure does not adversely affect the mirrors M1 to M6 of the projection optical system PO. The partition 7 is formed with an opening through which the exposure light EL passes. The space inside the partition 7 is exhausted to a predetermined degree of vacuum by a vacuum pump (not shown).

The main control system 31 is a control system including a computer that comprehensively controls the overall operation of the exposure apparatus 100. The main control system 31 controls the driving device (not shown) of the reticle holding unit 4 and the driving device (not shown) of the wafer holding unit 5 to move the reticle stage RST and the wafer stage.
In addition, the main control system 31 controls the driving device of the illumination optical system ILS to replace the aperture stop AS with one having an opening having a different shape, so that the illumination conditions are normal illumination, annular illumination, dipole illumination, Or switch to quadrupole illumination.

Further, the main control system 31 can obtain optical characteristics (such as various aberrations or wavefront aberration) of the projection optical system PO from the detection result of the aerial image measurement system 29 provided on the wafer stage WST of the wafer holding unit 5. .
The main control system 31 maintains the optical characteristics of the projection optical system PO by actively controlling the shape (surface shape) of the reflecting surface such as the mirror M1 using a driving device (not shown).
Further, the main control system 31 determines the position of the reticle R in the Z direction using, for example, a driving device of the reticle stage RST based on the measurement value of the reticle autofocus system provided in the vicinity of the reticle R during scanning exposure. Set within the allowable range.

  In the following, the Z axis is set in the normal direction of the surface of wafer stage WST on which wafer W is placed, the Y axis is set in a direction perpendicular to Z axis and parallel to the scanning direction of reticle stage RST, and Z axis A description will be given using an XYZ orthogonal coordinate system in which the X axis is set in a direction perpendicular to the Y axis.

A drive device (not shown) of the reticle holding unit 4 scans the reticle stage RST with a predetermined stroke in the Y direction based on a measurement value of a laser interferometer (not shown) and control information of the main control system 31. In addition, the driving device (not shown) of the reticle holding unit 4 can move the reticle stage RST in the X direction and the θz direction (rotation direction around the Z axis).
A driving device (not shown) of wafer holding unit 5 moves wafer stage WST at a predetermined stroke in the X and Y directions based on the measurement value of a laser interferometer (not shown) and the control information of main control system 31. . Further, a driving device (not shown) of wafer holding unit 5 drives wafer stage WST in the θz direction as necessary.

  When exposing the wafer W by the exposure apparatus 100, the reticle R and the wafer W are held by the reticle holding unit 4 and the wafer holding unit 5, and laser light is emitted from a laser light source (not shown) of the laser plasma light source 10. Laser light emitted from a laser light source (not shown) is condensed inside the condenser mirror 13 by the condenser lens 12 and irradiated onto the target supplied from the nozzle 14. Thereby, EUV light is generated and reflected by the collector mirror 13.

The exposure light EL reflected by the condensing mirror 13 is condensed at the focal point of the condensing mirror 13 and then reflected by the concave mirror 21 to become a substantially parallel light beam.
The exposure light EL reflected by the concave mirror 21 and converted into a substantially parallel light beam is guided to an optical integrator composed of fly-eye optical systems 22 and 23 and passes through the aperture stop AS. The exposure light EL that has passed through the aperture stop AS is once condensed and then reflected by the curved mirror 24 and the concave mirror 25 of the condenser optical system.

The exposure light EL reflected by the curved mirror 24 and the concave mirror 25 of the condenser optical system is shielded against the pattern region of the reticle R after the end in the -Y direction is shielded by, for example, an arcuate edge of the blind plate 26A. Irradiated from diagonally below. At this time, the exposure light EL reflected by the many reflecting mirror elements of the fly-eye optical systems 22 and 23 is applied to the pattern area of the reticle R by being superimposed by the curved mirror 24 and the concave mirror 25 of the condenser optical system. The
Thereby, a part of the pattern area of the reticle R (irradiation area 27R) is irradiated with the exposure light EL having a uniform illuminance distribution.

The exposure light EL irradiated to the irradiation region 27R is reflected from the reflection pattern formed in the pattern region of the reticle R. The exposure light EL reflected from the reflection pattern is incident on the projection optical system PO after its end in the + Y direction is shielded by, for example, an arcuate edge of the blind plate 26B. The exposure light EL that has entered the projection optical system PO is sequentially reflected by the mirrors M1 to M6, and is irradiated onto the exposure region (region conjugate to the irradiation region 27R) 27W of the wafer W.
Thereby, a reduced image of a part of the reflection pattern of the reticle R is projected onto the exposure area 27W of the wafer W.

In the present embodiment, the irradiation area 27R of the reticle R and the exposure area 27W of the wafer W have an arc shape elongated in the X direction.
Further, when the wafer W is exposed, the driving device for the reticle holding unit 4 and the wafer holding unit 5 is controlled by the main control system 31, and the reticle stage RST and wafer stage WST are synchronized according to the reduction magnification of the projection optical system PO. And drive. That is, when exposing one shot area (die) of the wafer W, the reticle R and the wafer W have the Y axis at a predetermined speed ratio according to the reduction magnification of the projection optical system PO with respect to the projection optical system PO. (Synchronous scanning).

  As a result, a pattern (reflection pattern) formed in the pattern area of the reticle R is exposed to one shot area of the wafer W. Thereafter, after the wafer stage WST is driven to move the wafer W stepwise, the pattern of the reticle R is scanned and exposed to the next shot area of the wafer W. In this way, a pattern image of the reticle R is sequentially exposed to a plurality of shot regions of the wafer W by the step-and-scan method.

Next, the reticle R of this embodiment will be described with reference to FIGS.
FIG. 2 is a schematic perspective view of the reticle R. FIG. FIG. 3 is a schematic cross-sectional view of the non-pattern region Rb of the reticle R.
As shown in FIG. 2, the reticle R of the present embodiment has a pattern region Ra and a non-pattern region Rb on the surface on which the exposure light EL (cleaning light EC) is incident.

  In the pattern region Ra, as described above, for example, a reflection pattern corresponding to a circuit pattern of an electronic circuit is formed. As shown in FIG. 1, the reflection pattern in the pattern region Ra reflects the exposure light EL emitted from the illumination optical system ILS toward the mirror M1 of the projection optical system PO. That is, the light irradiated to the pattern area Ra of the reticle R by the illumination optical system ILS and reflected by the reflection pattern of the pattern area Ra is reflected in the direction incident on the projection optical system PO.

  The non-pattern region Rb reflects (scatters) the cleaning light EC (exposure light EL) emitted from the illumination optical system ILS in various directions including a direction different from the reflection direction in which the pattern region Ra reflects the exposure light EL. To do. Specifically, as shown in FIG. 3, for example, a plurality of hemispherical convex portions Rc are provided in the non-pattern region Rb. The convex portion Rc has, for example, a reflective film that reflects the cleaning light EC, and is provided so as to reflect (scatter) the incident cleaning light EC in various directions. In this embodiment, since the cleaning light EC has the same wavelength as the EUV light, the reflective film is formed of a multilayer reflective film that reflects the EUV light.

As the multilayer reflective film, two types of substances having different refractive indices with respect to vacuum, for example, a structure in which molybdenum (Mo) and silicon (Si) are alternately stacked, a substance such as ruthenium (Ru), rhodium (Rh), A structure in which a substance such as Si, beryllium (Be), or carbon tetraboride (B ₄ C) is combined can be used. The multilayer reflective film of this embodiment has a configuration in which, for example, about 40 to 70 layers of Si and Mo are alternately stacked, and a capping layer is formed on the surface.

  The non-pattern region Rb can adopt a configuration different from the above configuration as long as it reflects incident EUV light in a direction different from the reflection direction reflected by the pattern region Ra. For example, the shape of the convex portion is not limited to a hemispherical shape, as long as it can reflect (scatter) EUV light. Further, the number of convex portions may be one. Moreover, you may form a recessed part instead of a convex part, and may combine a convex part and a recessed part. Further, the number of concave portions may be one or a large number.

  As shown in FIG. 2, the pattern area Ra and the non-pattern area Rb of the reticle R of the present embodiment are arranged adjacent to each other. In the present embodiment, when the reticle R is held by the reticle holding unit 4 of the exposure apparatus 100 shown in FIG. 1, the pattern area Ra and the non-pattern area Rb of the reticle R are adjacent in the direction along the Y axis. Arranged.

When the exposure apparatus 100 exposes one shot region of the wafer W, the reticle R and the wafer W move in synchronization with the projection optical system PO in a direction parallel to the Y axis. That is, the direction parallel to the Y axis is the scanning direction of the exposure light EL on the reticle R. Therefore, the pattern area Ra and the non-pattern area Rb of the reticle R are arranged adjacent to each other in the direction along the scanning direction of the exposure light EL.
Note that the pattern region Ra and the non-pattern region Rb are not necessarily arranged adjacent to each other.

Next, the light cleaning function of the exposure apparatus 100 will be described.
In the exposure apparatus 100, for example, contaminants such as organic substances may be generated from members or the like disposed inside the vacuum chamber 1.
Among contaminants generated in the vacuum chamber 1, those having a high boiling point easily adhere to the surfaces of various members inside the vacuum chamber 1.

When contaminants adhere to the reflecting surface of the optical element, a problem arises in that the reflectance of the optical element decreases.
In particular, EUV light causes carbon-based molecules floating in the vicinity thereof to adhere to the surface of the optical element. In addition, contaminants attached to members other than the optical element may eventually adhere to the surface of the optical element while repeatedly attaching to and detaching from members other than the optical element.

In order to solve such a problem, the exposure apparatus 100 of this embodiment has a light cleaning function for removing contaminants inside the vacuum chamber 1.
Hereinafter, a case where the non-pattern region Rb of the reticle R functions as a cleaning optical unit for performing optical cleaning will be described.

  When performing the optical cleaning, the reticle stage RST is moved by the driving device of the reticle holding unit 4 as shown in FIG. Then, the reticle R is moved so that the cleaning light EC (EUV light) emitted from the illumination optical system ILS is incident on the non-pattern region Rb of the reticle R.

Further, an oxidizing gas or a reducing gas is supplied into the vacuum chamber 1 from the gas supply unit 32B. As a result, a part of the area CA of the partition wall of the vacuum chamber 1, which is a part to be cleaned (cleaning target part), and the vicinity of the optical elements of the illumination optical system ILS and the projection optical system PO are oxidized gas or reducible. A gas atmosphere can be obtained. The oxidizing gas or reducing gas may be supplied as necessary depending on the state of contaminants inside the vacuum chamber 1, and may not be supplied in some cases.
Here, the oxidizing gas includes one or more gases selected from O ₂ , O ₃ , H ₂ O, H ₂ O ₂ , CO, and NO, and the reducing gas includes H ₂ . .

Thereafter, the cleaning light EC is generated by the laser plasma light source 10, and the non-pattern region of the reticle R is irradiated with the cleaning light EC via the illumination optical system ILS.
The cleaning light EC emitted from the illumination optical system ILS and incident on the non-pattern region Rb of the reticle R is reflected (scattered) by the plurality of convex portions Rc of the non-pattern region Rb.

  The cleaning light EC reflected (scattered) by the plurality of convex portions Rc in the non-pattern area Rb is reflected (scattered) in various directions including a direction different from the reflection direction reflected by the pattern area Ra. As a result, the cleaning light EC is irradiated onto the partial area CA of the partition wall of the vacuum chamber 1 that is the cleaning target part, the optical elements of the illumination optical system ILS, the projection optical system PO, and the like. Further, a part of the cleaning light EC is reflected toward the projection optical system PO, and a part thereof is reflected toward the illumination optical system ILS. However, the cleaning EC incident on the projection optical system PO and the cleaning EC incident on the illumination optical system ILS reach each mirror along an optical path different from the optical path of the exposure light EL. Then, the contaminants adhering to these cleaning target parts are promoted to be detached from the cleaning target parts by the action of the cleaning light EC. Specifically, the desorption of organic gas mainly from the substance adsorbed on the member surface is promoted. Also, the contaminants are broken and vaporize into lower molecular and more volatile molecules.

Further, when the oxidizing gas or the reducing gas is disposed in the vicinity of the cleaning target portion, a contaminant such as a carbon film attached to the cleaning target portion can be oxidized or reduced. As a result, the contaminant attached to the cleaning target portion is changed to a material that is easier to remove, such as CO ₂ or H ₂ O, or CH ₄ , and the contaminant is effectively removed from the cleaning target portion. Can do.

  The contaminants desorbed and removed from the cleaning target portion are sucked by the vacuum pump 32A and discharged to the outside of the vacuum chamber 1. As a result, the contaminants detached and removed from the cleaning target portion are prevented from adhering again to the partition walls of the vacuum chamber 1, the illumination optical system ILS, the optical elements of the projection optical system PO, and the like. As described above, the portion to be cleaned to which the contaminant is attached can be optically cleaned.

  The exposure apparatus 100 of the present embodiment has a reticle R having a non-pattern region Rb as a light cleaning optical unit for performing light cleaning. Therefore, even when contaminants adhere to the partition walls of the vacuum chamber 1 or members inside the vacuum chamber 1, the adhered contaminants can be detached and removed and discharged to the outside of the vacuum chamber 1.

  Therefore, according to the exposure apparatus 100 of the present embodiment, contaminants inside the vacuum chamber 1 can be reduced, and contaminants attached to the optical elements of the illumination optical system ILS and the projection optical system PO can be reduced. it can. Thereby, it is possible to prevent the reflectance of the optical elements of the illumination optical system ILS and the projection optical system PO from being lowered, and to suppress the occurrence of uneven reflection of the optical elements. Therefore, the productivity of the exposure apparatus 100 can be improved and the life of the exposure apparatus 100 can be extended. Further, since the adhesion of contaminants to the optical element is reduced, the thermal expansion of the optical element can be reduced, the occurrence of uneven illuminance can be suppressed, and the optical performance of the optical element can be prevented from deteriorating. Therefore, the imaging performance of the exposure apparatus 100 can be maintained for a long time.

As described above, according to the reticle R, the exposure apparatus 100, and the exposure method using the exposure apparatus 100 of the present embodiment, the generation of contaminants can be effectively suppressed by performing optical cleaning.
In addition, since the pattern area Ra and the non-pattern area Rb are provided adjacent to the reticle R, the exposure apparatus 100 can be easily switched between exposure and cleaning.
Further, since the pattern area Ra and the non-pattern area Rb are provided adjacent to the scanning direction (direction along the Y axis) of the exposure light EL in the reticle R, the cleaning is continuously performed after the exposure. It becomes possible.

The embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and can be appropriately changed based on design requirements and the like without departing from the gist of the present invention.
For example, in the above embodiment, the case where the cleaning optical unit is provided on the reticle has been described. However, the cleaning optical unit may be provided on a wafer (photosensitive substrate) or a wafer stage. FIG. 4 is a perspective view showing an example when the cleaning optical part Wa is formed on the wafer W. FIG.

  As shown in FIG. 4, a plurality of cleaning optical parts Wa are formed in an area where the circuit pattern of the wafer W is not formed. The cleaning optical unit Wa may be a flat reflecting surface, for example, and may have the same configuration as the non-patterned portion of the reticle in the above-described embodiment. A cleaning optical unit similar to the cleaning optical unit Wa may be provided on the wafer stage (substrate stage). The cleaning optical unit Wa may be provided on both the wafer W and the wafer stage, or may be provided on either one.

Further, the cleaning optical unit may be provided on the reticle holder and the reticle stage in the exposure apparatus having the same configuration as the exposure apparatus in the above-described embodiment. The cleaning optical unit may be provided in a mirror holder that holds an optical element of the projection optical system.
FIG. 5 is an enlarged cross-sectional view showing an example of an exposure apparatus in which a cleaning optical unit is provided on the partition of the reticle holder, reticle stage, mirror holder, and vacuum chamber 1. The exposure apparatus shown in FIG. 5 has the same configuration as the exposure apparatus shown in FIG. 1 except for the part shown in FIG. To do.

  In the exposure apparatus shown in FIG. 5, cleaning optical units RHa and RSTa are provided on a reticle holder (mask holder) RH and a reticle stage (mask stage) RST, respectively. The mirror holder M1H that holds the mirror M1 is also provided with a cleaning optical unit M1a. Further, cleaning optical parts 1 a and 1 b are also provided in the partition wall of the vacuum chamber 1. The cleaning optical units RHa, RSTa, M1a, 1a, and 1b may be flat mirrors or may have the same configuration as the non-pattern unit described in the above embodiment. The cleaning optical unit may be provided in a part of the mirrors M1 to M6. Further, on the surface of the cleaning optical unit RHa, RSTa, M1a, 1a, 1b, a reflective film having a material and a structure suitable for obtaining a higher reflectance is formed according to the wavelength of the cleaning light EC. Is preferred.

  According to the exposure apparatus shown in FIG. 5, the cleaning optical part RHa, RSTa provided in the reticle holding part 4 causes the cleaning light EC to reflect the exposure light EL by the reflection pattern of the reticle R (reflection angle α). By reflecting (scattering) in different directions, contaminants adhering to the cleaning target portion can be detached and removed. Further, the cleaning light EC reflected by the cleaning optical units RHa and RSTa is further supplied by the cleaning optical unit M1a provided in the mirror holder M1H (or the mirror M1) and the cleaning optical units 1a and 1b provided in the vacuum chamber 1. It is possible to reflect (scatter) and irradiate the cleaning light EC over a wider range. Accordingly, the contaminants attached to the vacuum chamber 1 and the members disposed inside the vacuum chamber 1 can be effectively desorbed and removed, and the contaminants inside the vacuum chamber 1 can be reduced.

The photosensitive substrate in the above embodiment is not only a semiconductor wafer for manufacturing semiconductor devices, but also a glass substrate for display devices, a ceramic wafer for thin film magnetic heads, or a mask or reticle used in an exposure apparatus. An original plate (synthetic quartz, silicon wafer) or the like is applied.
As an exposure apparatus, in addition to a step-and-scan type scanning exposure apparatus (scanning stepper), the reticle R pattern is collectively exposed while the reticle R and the wafer W are stationary, and the wafer W is sequentially moved stepwise. The present invention can also be applied to a step-and-repeat projection exposure apparatus (stepper). The present invention can also be applied to a step-and-stitch type exposure apparatus that partially transfers at least two patterns on the wafer W.
Further, as disclosed in, for example, US Pat. No. 6,611,316, two reticle patterns are synthesized on a substrate via a projection optical system, and one scanning exposure is performed on one substrate on the substrate. The present invention can also be applied to an exposure apparatus that performs double exposure of shot areas almost simultaneously.
The type of the exposure apparatus is not limited to an exposure apparatus for manufacturing a semiconductor element that exposes a semiconductor element pattern on the wafer W, but is an exposure apparatus for manufacturing a liquid crystal display element or a display, a thin film magnetic head, an image sensor (CCD), It can be widely applied to an exposure apparatus for manufacturing a micromachine, a MEMS, a DNA chip, a reticle, a mask, or the like.

  Next, an embodiment of a manufacturing method of a micro device using the exposure apparatus and the exposure method according to the embodiment of the present invention in the lithography process will be described. FIG. 6 is a flowchart showing a manufacturing example of a micro device (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micro machine, etc.).

  First, in step S10 (design step), function / performance design (for example, circuit design of a semiconductor device) of a micro device is performed, and pattern design for realizing the function is performed. Subsequently, in step S11 (mask manufacturing step), a mask (reticle) on which the designed circuit pattern is formed is manufactured. On the other hand, in step S12 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.

  Next, in step S13 (wafer processing step), using the mask and wafer prepared in steps S10 to S12, an actual circuit or the like is formed on the wafer by lithography or the like, as will be described later. Next, in step S14 (device assembly step), device assembly is performed using the wafer processed in step S13. This step S14 includes processes such as a dicing process, a bonding process, and a packaging process (chip encapsulation) as necessary. Finally, in step S15 (inspection step), inspections such as an operation confirmation test and a durability test of the microdevice manufactured in step S14 are performed. After these steps, the microdevice is completed and shipped.

FIG. 7 is a diagram showing details of step S13 in the case of a semiconductor device.
In step S21 (oxidation step), the surface of the wafer is oxidized. In step S22 (CVD step), an insulating film is formed on the wafer surface. In step S23 (electrode formation step), an electrode is formed on the wafer by vapor deposition. In step S24 (ion implantation step), ions are implanted into the wafer. Each of the above steps S21 to S24 constitutes a pre-processing process at each stage of the wafer processing, and is selected and executed according to a necessary process at each stage.

  At each stage of the wafer process, when the above pre-process is completed, the post-process is executed as follows. In this post-processing process, first, in step S25 (resist formation step), a photosensitive agent is applied to the wafer. Subsequently, in step S26 (exposure step), the circuit pattern of the mask is transferred to the wafer by the lithography system (exposure apparatus) and the exposure method described above. Next, in step S27 (development step), the exposed wafer is developed, and in step S28 (etching step), exposed members other than the portion where the resist remains are removed by etching. In step S29 (resist removal step), the resist that has become unnecessary after the etching is removed. By repeatedly performing these pre-processing steps and post-processing steps, multiple circuit patterns are formed on the wafer.

In the above step S26, by appropriately performing optical cleaning, the generation of contaminants in the lithography system can be effectively suppressed.
The present invention is not limited to a micro device such as a semiconductor element, but a mother reticle for manufacturing a reticle or mask used in an optical exposure apparatus, an EUV exposure apparatus, an X-ray exposure apparatus, an electron beam exposure apparatus, and the like. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern to a glass substrate or silicon wafer.

DESCRIPTION OF SYMBOLS 1 ... Vacuum chamber (casing), 1a ... Cleaning optical part, 1b ... Cleaning optical part, 32B ... Gas supply part, 100 ... Exposure apparatus, EC ... Cleaning light (exposure light) EL ... Exposure light, ILS ... Illumination optics System, M1 ... mirror, M1a ... cleaning optical part, M1H ... mirror holder, PO ... projection optical system, R ... reticle (reflection mask), Ra ... pattern area, Rb ... non-pattern area, Rc ... convex part, RH ... Reticle holder (mask holder), RHa ... cleaning optical unit, RHb ... cleaning optical unit, RST ... reticle stage (mask stage), W ... wafer (photosensitive substrate), Wa ... cleaning optical unit, WST ... wafer stage (substrate stage) )

Claims (16)

A reflective mask having a pattern region provided with a reflective pattern,
A reflective mask having a non-pattern area that reflects or scatters incident light in a direction different from a reflection direction in which the pattern area reflects.   The reflective mask according to claim 1, wherein the pattern region and the non-pattern region are disposed adjacent to each other.   The reflective mask according to claim 2, wherein the pattern area and the non-pattern area are arranged adjacent to each other in a direction along a scanning direction of the light.   The reflective mask according to claim 1, wherein the non-pattern region has at least one convex portion or concave portion.   5. The reflective mask according to claim 1, wherein the non-pattern region further reflects incident light in the same direction as a reflection direction in which the pattern region reflects. An exposure apparatus for forming a pattern provided on a reflective mask on a photosensitive substrate,
An illumination optical system for irradiating the reflective mask with exposure light;
A projection optical system that exposes the photosensitive substrate with the exposure light reflected by the pattern;
An exposure apparatus comprising: a cleaning optical unit that reflects or scatters at least a part of the exposure light to irradiate at least a part of the reflected or scattered exposure light on a cleaning target part different from the photosensitive substrate. A mask holder that holds the reflective mask, and a mask stage that moves while holding the mask holder,
The exposure apparatus according to claim 6, wherein the cleaning optical unit is provided in at least one of the reflective mask, the mask holder, and the mask stage. The projection optical system includes a mirror that reflects the exposure light and guides it to the photosensitive substrate, and a mirror holder that holds the mirror,
The exposure apparatus according to claim 6, wherein the cleaning optical unit is provided in at least one of the mirror and the mirror holder. A substrate stage that holds and moves the photosensitive substrate;
The exposure apparatus according to claim 6, wherein the cleaning optical unit is provided on at least one of the photosensitive substrate and the substrate stage.   The exposure apparatus according to claim 6, further comprising a gas supply unit that supplies an oxidizing gas or a reducing gas in the vicinity of the cleaning target unit.   The exposure apparatus according to any one of claims 6 to 10, wherein the cleaning target part includes a part of a housing that houses the illumination optical system and the projection optical system. An exposure method for forming a pattern provided on a reflective mask on a photosensitive substrate,
Using the reflective mask according to any one of claims 1 to 5,
Irradiating the pattern region with the exposure light to expose the photosensitive substrate;
Irradiating the non-pattern area with the exposure light and photocleaning a portion to be cleaned different from the photosensitive substrate;
An exposure method comprising: An exposure method for forming a pattern provided on a reflective mask on a photosensitive substrate,
Using the exposure apparatus according to any one of claims 6 to 11,
Irradiating the reflective mask with the exposure light to expose the photosensitive substrate;
Irradiating the cleaning optical part with the exposure light to optically wash the object to be cleaned;
An exposure method comprising: The exposure method according to claim 12 or 13, comprising supplying an oxidizing gas or a reducing gas in the vicinity of the cleaning target portion when the cleaning target portion is optically cleaned. The oxidizing gas includes one or more gases selected from O ₂ , O ₃ , H ₂ O, H ₂ O ₂ , CO, and NO,
The exposure method according to claim 14, wherein the reducing gas contains H ₂ . Exposing the photosensitive substrate using the exposure apparatus according to any one of claims 6 to 11,
A device manufacturing method comprising processing the exposed photosensitive substrate.

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