JP2006173377A - Optical part and projection aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide optics capable of maintaining a reflectance of a light irradiation face for a long period of time. <P>SOLUTION: In a projection aligner, a mask R is illuminated on an exposure beam IL, and a pattern of the mask R is transferred onto a substrate W retained on substrate stages 9, 10 via a projection optical system PL. Optics 56 are mounted on the substrate stages 9, 10 of the projection aligner. The optics 56 comprise a light irradiation face to be irradiated by the exposure beam IL, an adhesion improvement metal layer formed on the surface of the light irradiation face, and a noble metal layer formed on the surface of the adhesion improvement metal layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides, for example, a projection exposure used for transferring a mask pattern onto a photosensitive substrate in a lithography process for manufacturing a device such as a semiconductor device, an imaging device (CCD), a liquid crystal display device, or a thin film magnetic head. The present invention relates to an optical component used in the apparatus and a projection exposure apparatus using the optical component.

  When manufacturing a semiconductor element or the like, an image of a reticle pattern as a mask is transferred to each shot area on a wafer (or glass plate or the like) coated with a resist as a photosensitive substrate via a projection optical system. A projection exposure apparatus is used. Conventionally, a step-and-repeat type reduction projection type exposure apparatus (stepper) has been widely used as a projection exposure apparatus, but recently, a step-and-scan system that performs exposure by synchronously scanning a reticle and a wafer. The projection exposure apparatus is also attracting attention.

  The resolution of the projection optical system provided in the projection exposure apparatus becomes higher as the exposure wavelength used becomes shorter and the numerical aperture of the projection optical system becomes larger. For this reason, along with the miniaturization of integrated circuits, the exposure wavelength used in the projection exposure apparatus has become shorter year by year, and the numerical aperture of the projection optical system has also increased. The mainstream exposure wavelength is 248 nm for a KrF excimer laser, but 193 nm for an ArF excimer laser having a shorter wavelength is also in practical use.

  In addition, since the glass material which has the transmittance | permeability which can ensure sufficient light quantity for exposure is ensured with the shortening of the wavelength of exposure light, while ensuring desired imaging performance, the lower surface of a projection optical system and the wafer surface are limited. The space is filled with a liquid such as water or an organic solvent, and the wavelength of exposure light in the liquid becomes 1 / n times that in air (n is the refractive index of the liquid, usually about 1.2 to 1.6). There has also been proposed an immersion type projection exposure apparatus that improves the resolution by utilizing this fact (see, for example, Patent Document 1).

JP-A-10-303114

  On the substrate stage of the above-described projection exposure apparatus, a fiducial mark (FM) in which a fine pattern is formed with a metal chromium film on a glass substrate is mounted. FM is an alignment of a substrate stage, a mask (reticle) Used for alignment and baseline measurement. Here, in reticle alignment, a reticle mark (RM) is irradiated with ultraviolet laser light, a reflected image of the RM reflected by the RM, and FM is irradiated with the ultraviolet laser light transmitted through the RM, and a part of the FM An image obtained by superimposing the reflected image of the FM reflected in step 1 is measured.

  At this time, the metallic chromium film formed on the FM reacts with oxygen present around by irradiation with ultraviolet laser light, and a chromium oxide layer is gradually formed on the FM surface. The transfer phenomenon in which the image of (RM) is transferred onto the FM occurs, and the reflectance of the portion where the transfer phenomenon on the FM surface occurs changes. Therefore, when using a different reticle, there is a problem that a measurement error occurs and high-precision measurement cannot be performed.

  The subject of this invention is providing the projection exposure apparatus provided with the optical component which can maintain the reflectance of a light irradiation surface for a long period of time, and this optical component.

  The optical component according to claim 1 is mounted on the substrate stage of a projection exposure apparatus that illuminates the mask with an exposure beam and transfers the pattern of the mask onto a substrate held on the substrate stage via a projection optical system. An optical component, a light irradiation surface irradiated with the exposure beam, an adhesion improving metal layer formed on a surface of the light irradiation surface, a noble metal layer formed on a surface of the adhesion improving metal layer, It is characterized by providing.

  The optical component according to claim 2 is characterized in that the adhesion improving metal layer is formed of at least one of chromium, molybdenum, tungsten, aluminum, silicon, germanium, and titanium.

  The optical component according to claim 3 is characterized in that the noble metal layer is formed of at least one of gold, platinum, palladium, rhodium, iridium, and ruthenium.

  The optical component according to claim 4 is characterized in that at least one of the adhesion improving metal layer and the noble metal layer is formed by vapor deposition or sputtering.

  According to the optical component according to any one of claims 1 to 4, adhesion of chromium or the like formed by vapor deposition or the like between the light irradiation surface and a noble metal layer having a high reflectance such as platinum formed by vapor deposition or the like. Since the improved metal layer is formed, the noble metal layer can be reliably adhered onto the light irradiation surface, and peeling of the noble metal layer from the light irradiation surface can be prevented. Further, since the noble metal layer formed on the light irradiation surface does not oxidize even when irradiated with ultraviolet laser light, for example, a mask formed on the mask by irradiation with ultraviolet laser light for measurement. It is possible to prevent the transfer phenomenon in which the mark image is transferred to the light irradiation surface. Therefore, the reflectance on the light irradiation surface (noble metal layer) can be maintained for a long time in a constant state.

  The optical component according to claim 5 illuminates the mask with an exposure beam and transfers the pattern of the mask onto the substrate held on the substrate stage via the projection optical system on the substrate stage. An optical component mounted on the light irradiation surface irradiated with the exposure beam; a high reflectance metal layer formed on a surface of the light irradiation surface; and a surface of the high reflectance metal layer. And an anti-oxidation layer for preventing oxidation of the high reflectivity metal layer.

  The optical component according to claim 6 is characterized in that the high reflectivity metal layer is formed of at least one of chromium, molybdenum, tungsten, aluminum, silicon, and germanium.

  The optical component according to claim 7 is characterized in that the antioxidant layer is formed of at least one of chromium oxide, molybdenum oxide, tungsten oxide, aluminum oxide, silicon dioxide, and titanium oxide.

  The optical component according to claim 8 is characterized in that at least one of the high reflectivity metal layer and the antioxidant layer is formed by vapor deposition or sputtering.

  The optical component according to claim 9 is characterized in that the light irradiation surface has a base glass.

  According to the optical component of claims 5 to 9, an anti-oxidation layer such as chromium oxide formed by vapor deposition or the like is formed on the surface of the high reflectivity metal layer such as chromium formed by vapor deposition or the like. Therefore, it is possible to prevent oxidation of the high reflectivity metal layer caused by irradiation with ultraviolet laser light. Therefore, for example, by irradiating measurement ultraviolet laser light, it is possible to prevent the occurrence of a transfer phenomenon in which the image of the mask mark formed on the mask is transferred to the light irradiation surface. The reflectance of the high reflectance metal layer) can be maintained for a long time in a constant state.

  The projection exposure apparatus according to claim 10 is a projection exposure apparatus that illuminates a mask with an exposure beam and transfers a pattern of the mask onto a substrate held on a substrate stage via a projection optical system, The optical component according to any one of claims 1 to 9 is provided on the substrate stage.

  According to the projection exposure apparatus of the tenth aspect, since the optical component used for the alignment of the substrate stage according to any one of the first to ninth aspects is provided on the substrate stage, an ultraviolet laser is provided. By irradiating light, it is possible to prevent the occurrence of a transfer phenomenon in which the image of the mask mark formed on the mask is transferred to the optical component, and to maintain the reflectance of the optical component in a constant state for a long time. be able to. Therefore, even when the mask mark is changed by exchanging the mask, the alignment of the substrate stage can be performed with high accuracy.

  The projection exposure apparatus according to claim 11 is characterized in that a predetermined liquid is interposed between the surface of the substrate and the optical component on the substrate side of the projection optical system.

  According to the projection exposure apparatus of the eleventh aspect, the predetermined liquid is interposed between the surface of the substrate and the optical component on the substrate side of the projection optical system, and the first to ninth aspects of the invention are provided on the substrate stage. The optical component used for the alignment of the substrate stage as described in any one of the above is provided. Therefore, since it is possible to prevent oxidation caused by irradiation with ultraviolet laser light and oxidation caused by the liquid being interposed, the reflectance of the optical component can be maintained in a constant state for a long period of time. Even when the mask mark is changed by exchanging the mask, the substrate stage can be aligned with high accuracy.

  According to the optical component of the present invention, since the adhesion improving metal layer such as chromium formed by vapor deposition or the like is formed between the light irradiation surface and the noble metal layer such as platinum formed by vapor deposition or the like, the noble metal layer Can be reliably adhered onto the light irradiation surface, and peeling of the noble metal layer from the light irradiation surface can be prevented. In addition, the noble metal layer formed on the light-irradiated surface or the high-reflectance metal layer having the anti-oxidation layer formed on the surface does not oxidize even when irradiated with ultraviolet laser light for measurement. By irradiating the laser beam, it is possible to prevent the occurrence of a transfer phenomenon in which the image of the mask mark formed on the mask is transferred to the light irradiation surface. Therefore, the reflectance on the light irradiation surface can be maintained for a long time in a constant state.

  Further, according to the projection exposure apparatus of the present invention, since the optical component used for alignment of the substrate stage according to the present invention is provided on the substrate stage, the mask is irradiated with the ultraviolet laser beam for measurement. It is possible to prevent the occurrence of a transfer phenomenon in which the mask mark image formed on the optical component is transferred to the optical component, and to maintain the reflectance of the ultraviolet laser light reflected by the optical component in a constant state for a long period of time. it can. Therefore, even when the mask mark is changed by exchanging the mask, the alignment of the substrate stage can be performed with high accuracy.

  A projection exposure apparatus according to a first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a step-and-repeat projection exposure apparatus according to the first embodiment. In the following description, the XYZ orthogonal coordinate system shown in FIG. 1 is set, and the positional relationship of each member will be described with reference to this XYZ orthogonal coordinate system. The XYZ orthogonal coordinate system is set so that the X axis and the Y axis are parallel to the wafer W, and the Z axis is set in a direction orthogonal to the wafer W. In the XYZ coordinate system in the figure, the XY plane is actually set to a plane parallel to the horizontal plane, and the Z-axis is set vertically upward.

As shown in FIG. 1, the projection exposure apparatus according to this embodiment includes an ArF excimer laser light source as an exposure light source, and includes an illumination optical system 1 including an optical integrator (homogenizer), a field stop, a condenser lens, and the like. It has. Exposure light (exposure beam) IL made up of ultraviolet pulsed light having a wavelength of 193 nm emitted from a light source passes through the illumination optical system 1 and illuminates a pattern provided on a reticle (mask) R. The light that has passed through the reticle R is incident on the telecentric projection optical system PL on both sides (or one side on the wafer W side). The projection optical system PL includes a lens barrel 3 that houses a plurality of optical elements constituting the projection optical system PL, and light that has passed through the plurality of optical elements accommodated by the lens barrel 3 is projected into the projection optical system PL. Is incident on the optical element 4 closest to the wafer W. The light that has passed through the optical element 4 reaches the exposure region on the wafer (substrate) W coated with the photoresist, and the pattern of the reticle R has a predetermined projection magnification β (for example, β is 1/4 or 1/5). Etc.) and reduced projection exposure. As the exposure light IL, KrF excimer laser light (wavelength 248 nm), F ₂ laser light (wavelength 157 nm), or the like may be used.

  The reticle R is held on a reticle stage RST, and a mechanism for finely moving the reticle R in the X direction, the Y direction, and the rotation direction is incorporated in the reticle stage RST. The positions of the reticle stage RST in the X direction, the Y direction, and the rotational direction are measured and controlled in real time by a reticle laser interferometer (not shown).

  The wafer W is fixed on the Z stage 9 via a wafer holder (not shown). The Z stage 9 is fixed on an XY stage 10 that moves along an XY plane substantially parallel to the image plane of the projection optical system PL, and the focus position (position in the Z direction) and tilt angle of the wafer W are set. Control. The positions of the Z stage 9 in the X direction, the Y direction, and the rotation direction are measured and controlled in real time by a wafer laser interferometer 13 using a moving mirror 12 positioned on the Z stage 9. The XY stage 10 is placed on the base 11 and controls the X direction, Y direction, and rotation direction of the wafer W.

  The main control system 14 provided in the projection exposure apparatus adjusts the position of the reticle R in the X direction, the Y direction, and the rotational direction based on the measurement values measured by the reticle laser interferometer. That is, the main control system 14 adjusts the position of the reticle R by transmitting a control signal to a mechanism incorporated in the reticle stage RST and finely moving the reticle stage RST.

  Also, the main control system 14 adjusts the focus position (position in the Z direction) and the tilt angle of the wafer W in order to adjust the surface on the wafer W to the image plane of the projection optical system PL by the auto focus method and the auto leveling method. To do. That is, the main control system 14 outputs a control signal to the wafer stage drive system 15 and drives the Z stage 9 by the wafer stage drive system 15 to adjust the focus position and tilt angle of the wafer W. Further, the main control system 14 adjusts the position of the wafer W in the X direction, the Y direction, and the rotation direction based on the measurement values measured by the wafer laser interferometer 13. That is, the main control system 14 outputs a control signal to the wafer stage drive system 15 and drives the XY stage 10 by the wafer stage drive system 15 to adjust the position of the wafer W in the X direction, Y direction, and rotation direction. To do.

  FIG. 2 shows an optical component (fiducial mark 56) mounted on the Z stage (wafer stage) 9, and the positional relationship between the tip 4A of the optical element 4 provided in the projection optical system PL and the wafer W. FIG.

  As shown in FIG. 2, on the Z stage 9, an optical element that functions as a fiducial mark (FM) 56 used when aligning the reticle R and the wafer W and has a light irradiation surface on which alignment light is irradiated. Parts are mounted. FIG. 3 is a diagram showing the configuration of the fiducial mark 56 mounted on the Z stage (wafer stage) 9. The fiducial mark (FM) 56 has a base glass (quartz glass) 60, and a chromium (Cr) layer (adhesion improvement) formed on the surface of the base glass 60 by a vacuum deposition method or a sputtering method. Metal layer) 62 is formed. Further, a platinum (Pt) layer (noble metal layer) 64 formed by vacuum deposition or sputtering is formed on the surface of the chromium layer 62, and a fine pattern is formed by the platinum layer 64. . The chromium layer 62 is used to improve the adhesion between the base glass 60 and the platinum layer 64. The platinum layer 64 has a high light reflectivity and has a thickness that does not allow it to pass through.

  This projection exposure apparatus includes a reticle alignment system RAL that detects the relative positional relationship between a reticle mark RM and a fiducial mark (FM) 56 positioned on the reticle R. The reticle alignment system RAL is a light source (not shown) that emits ultraviolet laser light as alignment light, and an optical system (not shown) that guides alignment light emitted from the light source to a reticle mark RM and a fiducial mark (FM) 56. And an imaging unit (not shown) for detecting an image of the reticle mark RM and an image of the fiducial mark (FM) 56.

  Alignment light (ultraviolet laser light) emitted from the light source of the reticle alignment system RAL reaches the reticle mark RM via an optical system provided in the reticle alignment system RAL. The alignment light reflected by the reticle mark RM is incident on the imaging unit of the reticle alignment system RAL via an optical system provided in the reticle alignment system RAL. On the other hand, the alignment light that has passed through reticle mark RM is reflected by fiducial mark (FM) 56 through projection optical system PL. The alignment light reflected by the fiducial mark (FM) 56 enters the imaging unit of the reticle alignment system RAL via an optical system provided in the reticle alignment system RAL. A detection signal indicating the relative positional relationship between the reticle mark RM and the fiducial mark (FM) 56 detected by the imaging unit is output to the main control system 14.

  The projection exposure apparatus also includes a wafer alignment system WAL that detects a relative positional relationship between a wafer mark (not shown) located on the wafer W and a fiducial mark (FM) 56. Wafer alignment system WAL includes a light source (not shown) that emits alignment light, an optical system (not shown) that guides alignment light emitted from the light source to a wafer mark and fiducial mark (FM) 56 (not shown), and An imaging unit (not shown) for detecting an image of the wafer mark and an image of the fiducial mark (FM) 56 is provided.

  The alignment light emitted from the light source of the wafer alignment system WAL reaches a wafer mark or fiducial mark (FM) 56 via an optical system provided in the wafer alignment system WAL. The alignment light reflected by the wafer mark or fiducial mark (FM) 56 enters the imaging unit of the wafer alignment system WAL via an optical system provided in the wafer alignment system WAL. A detection signal indicating a relative positional relationship between the wafer mark and the fiducial mark (FM) 56 detected by the imaging unit is output to the main control system 14.

  The main control system 14 is a detection signal indicating the relative positional relationship between the reticle mark RM and fiducial mark (FM) 56 output from the reticle alignment system RAL, and the wafer mark and fiducial output from the wafer alignment system WAL. Based on the detection signal indicating the relative positional relationship with the mark (FM) 56, the relative position between the reticle R and the wafer W is adjusted by driving the XY stage 10 by the wafer stage drive system 15.

  At the time of exposure, the main control system 14 outputs a control signal to the wafer stage drive system 15 and drives the XY stage 10 by the wafer stage drive system 15 to sequentially step each shot area on the wafer W to the exposure position. Move. That is, the operation of exposing the pattern image of the reticle R onto the wafer W by the step-and-repeat method is repeated.

  According to the optical component of the first embodiment, since the chromium layer is formed between the light irradiation surface of the fiducial mark on the quartz glass and the platinum layer, the platinum layer is placed on the quartz glass. It is possible to reliably adhere to the light irradiation surface, and to prevent the platinum layer from peeling from the light irradiation surface. In addition, the platinum layer formed on the light irradiation surface does not oxidize even when irradiated with ultraviolet laser light, which is alignment light of the reticle alignment system. Occurrence of a transfer phenomenon in which an image is transferred to a light irradiation surface of a fiducial mark can be prevented. Therefore, the reflectance for the ultraviolet laser light (reticle alignment system alignment light) reflected by the fiducial mark (platinum layer) can be maintained for a long time in a constant state.

  In addition, according to the projection exposure apparatus according to the first embodiment, since the fiducial mark capable of maintaining the reflectance for a long time is provided on the Z stage, the occurrence of the transfer phenomenon can be prevented. By exchanging the reticle, alignment of the reticle stage and XY stage (wafer stage) can be performed with high accuracy even when different reticle marks are used.

  In the optical component according to the first embodiment, a chromium layer is formed as a metal layer on the light-irradiated surface of the base glass that functions as a fiducial mark, but chromium, molybdenum, tungsten, A layer made of at least one of aluminum, silicon, germanium, and titanium may be formed. Further, a platinum layer is formed as a noble metal layer on the surface of the chromium layer as the adhesion improving metal layer, but a layer composed of at least one of gold, platinum, palladium, rhodium, iridium, and ruthenium is formed. It may be.

  Further, in the optical component according to the first embodiment, the chromium layer as the adhesion improving metal layer and the platinum layer as the noble metal layer are formed by the vacuum evaporation method and the sputtering method. The film may be formed by a method.

  Next, a projection exposure apparatus according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a diagram showing a schematic configuration of a step-and-repeat type projection exposure apparatus according to the second embodiment. In the following description, the XYZ orthogonal coordinate system shown in FIG. 4 is set, and the positional relationship of each member will be described with reference to this XYZ orthogonal coordinate system. The XYZ orthogonal coordinate system is set so that the X axis and the Y axis are parallel to the wafer W, and the Z axis is set in a direction orthogonal to the wafer W. In the XYZ coordinate system in the figure, the XY plane is actually set to a plane parallel to the horizontal plane, and the Z-axis is set vertically upward. In FIG. 4, the same components as those in the projection exposure apparatus according to the first embodiment are denoted by the same reference numerals as those used in the first embodiment.

In the projection exposure apparatus according to this embodiment, the exposure light (exposure beam) IL emitted from the illumination optical system 1 including the ArF excimer laser light source that is the exposure light source has a pattern provided on the reticle (mask) R. Illuminates and reaches the projection area (exposure area) on the wafer (substrate) W via the projection optical system PL, and the pattern of the reticle R is subjected to reduced projection exposure at a predetermined projection magnification. As the exposure light, KrF excimer laser (wavelength 248 nm), F ₂ laser light (wavelength 157 nm), or the like may be used.

  The reticle R is held by a reticle stage RST, and the position of the reticle stage RST in the X direction, the Y direction, and the rotational direction is measured by a reticle laser interferometer (not shown). The wafer W is held by the Z stage 9 and fixed to the XY stage 10. The Z stage 9 is measured for positions in the X direction, the Y direction, and the rotational direction by a wafer laser interferometer 13 using a movable mirror 12.

  The main control system 14 adjusts the position of the reticle stage RST or Z stage (substrate stage) 9 in the X direction, Y direction, and rotation direction based on the measurement values measured by the reticle laser interferometer or the wafer laser interferometer 13. Do. The main control system 14 adjusts the focus position and the tilt angle of the wafer W by driving the Z stage 9 by the wafer stage drive system 15.

  In this projection exposure apparatus, an immersion method is applied to substantially shorten the exposure wavelength and improve the resolution. Here, in the immersion type projection exposure apparatus to which the immersion method is applied, at least during the transfer of the pattern image of the reticle R onto the wafer W, the surface of the wafer W and the wafer W side of the projection optical system PL. A predetermined liquid 7 is filled between the front end surface (lower surface) of the optical element 4. The projection optical system PL includes a lens barrel 3 that houses a plurality of optical elements formed of quartz or fluorite constituting the projection optical system PL. In this projection optical system PL, the optical element 4 closest to the wafer W is made of fluorite, and only the tip 4A on the wafer W side of the optical element 4 is in contact with the liquid 7. As a result, corrosion of the lens barrel 3 made of metal is prevented.

  As the liquid 7, pure water which can be easily obtained in large quantities at a semiconductor manufacturing factory or the like is used. Since pure water has a very low impurity content, it can be expected to clean the surface of the wafer W.

  The projection exposure apparatus includes a liquid supply device 5 that controls the supply of the liquid 7 and a liquid recovery device 6 that controls the discharge of the liquid 7. FIG. 5 is a diagram showing a positional relationship between the tip portion 4A and the wafer W of the optical element 4 of the projection optical system PL, and two pairs of discharge nozzles and inflow nozzles that sandwich the tip portion 4A in the X direction. FIG. 6 is a diagram showing a positional relationship between the tip portion 4A of the optical element 4 of the projection optical system PL and two pairs of discharge nozzles and inflow nozzles that sandwich the tip portion 4A in the Y direction.

  The liquid supply device 5 includes a liquid 7 tank (not shown), a pressure pump (not shown), a temperature control device (not shown), and the like. Further, as shown in FIG. 5, the liquid supply device 5 includes a discharge nozzle 21 a having a thin tip on the + X direction side of the tip 4 </ b> A via the supply pipe 21, and the tip of the tip 4 </ b> A via the supply pipe 22. A discharge nozzle 22a having a thin tip portion is connected to the −X direction side. Further, as shown in FIG. 6, the liquid supply device 5 includes a discharge nozzle 27 a having a thin tip on the + Y direction side of the tip 4 </ b> A via the supply pipe 27. A discharge nozzle 28a having a thin tip portion is connected to the −Y direction side. The liquid supply device 5 adjusts the temperature of the liquid 7 by a temperature control device, and at least one of the discharge nozzles 21a, 22a, 27a, and 28a has at least one of the supply pipes 21, 22, 27, and 28. The temperature-adjusted liquid 7 is supplied onto the wafer W through one supply pipe. The temperature of the liquid 7 is set by the temperature control device to be approximately the same as the temperature in the chamber in which the projection exposure apparatus according to this embodiment is housed, for example.

  The liquid recovery apparatus 6 includes a liquid 7 tank (not shown), a suction pump (not shown), and the like. In addition, in the liquid recovery apparatus 6, as shown in FIG. 5, inflow nozzles 23 a and 23 b having a wide front end portion on the −X direction side of the front end portion 4 </ b> A via the recovery tube 23 are provided via the recovery tube 24. Inflow nozzles 24a and 24b having wide tip portions are connected to the + X direction side of the portion 4A. The inflow nozzles 23a, 23b, 24a, and 24b are arranged in a fan-like shape with respect to an axis that passes through the center of the tip portion 4A and is parallel to the X axis. In addition, in the liquid recovery device 6, as shown in FIG. 6, inflow nozzles 29 a and 29 b having wide tip portions on the + Y direction side of the tip portion 4 </ b> A via the recovery tube 29 are provided via the recovery tube 30. Inflow nozzles 30a and 30b having wide tip portions are connected to the −Y direction side of 4A. The inflow nozzles 29a, 29b, 30a, and 30b are arranged in a fan-like shape with respect to an axis that passes through the center of the tip portion 4A and is parallel to the Y axis.

  The liquid recovery device 6 includes at least one recovery pipe in the recovery pipes 23, 24, 29, 30 from at least one inflow nozzle in the inflow nozzles 23a and 23b, 24a and 24b, 29a and 29b, 30a and 30b. The liquid 7 is recovered from the wafer W via

  Next, a method for supplying and collecting the liquid 7 will be described. In FIG. 5, when the wafer W is stepped in the direction of the arrow 25A indicated by the solid line (−X direction), the liquid supply device 5 uses the supply pipe 21 and the discharge nozzle 21a to move the tip 4A of the optical element 4 through the supply pipe 21 and the discharge nozzle 21a. The liquid 7 is supplied between the wafer W and the wafer W. The liquid recovery device 6 recovers the liquid 7 supplied between the front end portion 4A and the wafer W by the liquid supply device 5 from above the wafer W via the recovery pipe 23 and the inflow nozzles 23a and 23b. In this case, the liquid 7 flows on the wafer W in the direction of the arrow 25B (−X direction), and the space between the wafer W and the optical element 4 is stably filled with the liquid 7.

  On the other hand, in FIG. 5, when the wafer W is step-moved in the direction of the arrow 26A indicated by the chain line (+ X direction), the liquid supply apparatus 5 passes through the supply pipe 22 and the discharge nozzle 22a to the tip of the optical element 4. Liquid 7 is supplied between 4A and wafer W. The liquid recovery apparatus 6 recovers the liquid 7 supplied between the front end portion 4A and the wafer W by the liquid recovery apparatus 5 via the recovery pipe 24 and the inflow nozzles 24a and 24b. In this case, the liquid 7 flows on the wafer W in the direction of the arrow 26B (+ X direction), and the space between the wafer W and the optical element 4 is stably filled with the liquid 7.

  Further, when stepping the wafer W in the Y direction, the liquid 7 is supplied and recovered from the Y direction. That is, in FIG. 6, when the wafer W is stepped in the direction of the arrow 31A indicated by the solid line (−Y direction), the liquid supply device 5 supplies the liquid 7 via the supply pipe 27 and the discharge nozzle 27a. To do. The liquid recovery device 6 recovers the liquid 7 supplied between the tip 4A and the wafer W by the liquid supply device 5 via the recovery pipe 29 and the inflow nozzles 29a and 29b. In this case, the liquid 7 flows in the direction of the arrow 31 </ b> B (−Y direction) on the exposure region immediately below the distal end portion 4 </ b> A of the optical element 4.

  Further, when the wafer W is stepped in the + Y direction, the liquid supply device 5 supplies the liquid 7 via the supply pipe 28 and the discharge nozzle 28a. The liquid recovery device 6 recovers the liquid 7 supplied between the front end 4A and the wafer W by the liquid supply device 5 via the recovery pipe 30 and the inflow nozzles 30a and 30b. In this case, the liquid 7 flows in the + Y direction on the exposure region immediately below the distal end portion 4A of the optical element 4.

  In addition to the nozzle that supplies and recovers the liquid 7 from the X direction or the Y direction, for example, a nozzle that supplies and recovers the liquid 7 from an oblique direction may be provided.

  Next, a method for controlling the supply amount and the recovery amount of the liquid 7 will be described. FIG. 7 is a diagram showing a state in which the liquid 7 is supplied and recovered between the optical element 4 constituting the projection optical system PL and the wafer W. As shown in FIG. 7, when the wafer W is moving in the direction of the arrow 25A (−X direction), the liquid 7 supplied from the discharge nozzle 21a flows in the direction of the arrow 25B (−X direction) It is collected by the inflow nozzles 23a and 23b. Even when the wafer W is moving, in order to keep the amount of the liquid 7 filled between the optical element 4 and the wafer W constant, the supply amount and the recovery amount of the liquid 7 are made equal. Further, the supply amount and the recovery amount of the liquid 7 are adjusted based on the moving speed of the XY stage 10 (wafer W). The liquid 7 is always filled between the optical element 4 and the wafer W by adjusting the supply amount and the recovery amount of the liquid 7.

Further, as shown in FIG. 5, the projection exposure apparatus functions as a fiducial mark (FM) 560 used when aligning the reticle R and the wafer W on the Z stage 9, and irradiated with alignment light. An optical component having a light irradiation surface. FIG. 8 is a diagram showing the configuration of the fiducial mark 560 mounted on the Z stage (wafer stage) 9. The fiducial mark (FM) 560 includes a base glass (quartz glass) 600, and a chromium (Cr) layer (high reflection) formed on the surface of the base glass 600 by a vacuum deposition method or a sputtering method. Rate metal layer) 620 is formed, and the chromium layer 620 forms a fine pattern. In addition, a silicon dioxide (SiO ₂ ) layer (antioxidation layer) 640 formed by vacuum deposition or sputtering is formed on the surface of the chromium layer 620. This silicon dioxide layer 640 is formed to prevent oxidation of the chromium layer 620. The chromium layer 620 has a high light reflectivity and a thickness that does not allow it to pass through.

  This projection exposure apparatus includes a reticle alignment system RAL that detects the relative positional relationship between a reticle mark RM and a fiducial mark (FM) 560 positioned on the reticle R. Since the configuration of the reticle alignment system RAL according to this embodiment is the same as the configuration of the reticle alignment system RAL according to the first embodiment, description thereof is omitted.

  Alignment light (ultraviolet laser light) emitted from the light source of the reticle alignment system RAL reaches the reticle mark RM via an optical system provided in the reticle alignment system RAL. The alignment light reflected by the reticle mark RM is incident on the imaging unit of the reticle alignment system RAL via an optical system provided in the reticle alignment system RAL. On the other hand, the alignment light that has passed through reticle mark RM is reflected by fiducial mark (FM) 560 via projection optical system PL. The alignment light reflected by the fiducial mark (FM) 560 enters the imaging unit of the reticle alignment system RAL via an optical system provided in the reticle alignment system RAL. A detection signal indicating the relative positional relationship between the reticle mark RM and the fiducial mark (FM) 560 detected by the imaging unit is output to the main control system 14.

  The projection exposure apparatus also includes a wafer alignment system WAL that detects the relative positional relationship between a wafer mark (not shown) located on the wafer W and a fiducial mark (FM) 560. Since the configuration of the wafer alignment system WAL according to this embodiment is the same as the configuration of the wafer alignment system WAL according to the first embodiment, description thereof is omitted.

  Alignment light emitted from the light source of wafer alignment system WAL reaches a wafer mark or fiducial mark (FM) 560 via an optical system provided in wafer alignment system WAL. The alignment light reflected by the wafer mark or fiducial mark (FM) 560 enters the imaging unit of the wafer alignment system WAL via an optical system provided in the wafer alignment system WAL. A detection signal indicating the relative positional relationship between the wafer mark and the fiducial mark (FM) 560 detected by the imaging unit is output to the main control system 14.

  The main control system 14 detects a detection signal indicating the relative positional relationship between the reticle mark RM and the fiducial mark (FM) 560 output from the reticle alignment system RAL, and the wafer mark and fiducial output from the wafer alignment system WAL. Based on the detection signal indicating the relative positional relationship with the mark (FM) 560, the relative position between the reticle R and the wafer W is adjusted by driving the XY stage 10 by the wafer stage drive system 15.

  At the time of exposure, the main control system 14 transmits a control signal to the wafer stage drive system 15 and drives the XY stage 10 by the wafer stage drive system 15 to sequentially step each shot area on the wafer W to the exposure position. . That is, the operation of exposing the pattern image of the reticle R onto the wafer W by the step-and-repeat method is repeated.

  According to the optical component according to the second embodiment, since the silicon dioxide layer is formed on the surface of the highly reflective metal layer such as chromium, the ultraviolet laser light that is the alignment light of the reticle alignment system is irradiated. As a result, oxidation of the high reflectivity metal layer such as chromium can be prevented. Therefore, the irradiation of the ultraviolet laser light can prevent the occurrence of a transfer phenomenon in which the image of the reticle mark formed on the reticle is transferred to the light irradiation surface of the fiducial mark. The reflectance of the (high reflectance metal layer) can be maintained for a long time in a constant state.

  Further, according to the projection exposure apparatus according to the second embodiment, since the fiducial mark capable of maintaining the reflectance for a long time is provided on the Z stage, the occurrence of the transfer phenomenon can be prevented. Even when the reticle mark is changed by exchanging the reticle, alignment of the reticle stage or XY stage (wafer stage) can be performed with high accuracy.

In the optical component according to the second embodiment, a chromium layer is formed as a high reflectance metal layer on the light irradiation surface of the base glass that functions as a fiducial mark. A layer made of at least one of tungsten, aluminum, silicon, and germanium may be formed. In addition, a silicon dioxide (SiO ₂ ) layer is formed as an anti-oxidation layer on the surface of the chromium layer as the high reflectivity metal layer, but chromium oxide, molybdenum oxide, tungsten oxide, aluminum oxide, silicon dioxide, titanium oxide A layer comprising at least one of them may be formed.

  In the optical component according to the second embodiment, a chromium layer as a high reflectance metal layer and a silicon dioxide layer as an antioxidant layer are formed by vacuum deposition and sputtering. The film may be formed by the film forming method.

  Further, in the projection exposure apparatus according to the second embodiment, an optical component in which a high reflectance metal layer is formed on the surface of the light irradiation surface and an antioxidant layer is formed on the surface of the high reflectance metal layer. However, an optical component similar to the optical component according to the first embodiment may be provided. That is, an optical component in which a chromium layer as an adhesion improving metal layer is formed on the surface of the light irradiation surface and a platinum layer as a noble metal layer is formed on the surface of the chromium layer may be provided. The adhesion improving metal layer may be a layer made of at least one of chromium, molybdenum, tungsten, aluminum, silicon, germanium, and titanium, and the noble metal layer may be gold, platinum, palladium, rhodium, iridium, ruthenium. Any layer of at least one of them may be used.

  In the projection exposure apparatus according to the first embodiment described above, an optical component in which a non-adhesion improving metal layer is formed on the surface of the light irradiation surface and a noble metal layer is formed on the surface of the adhesion improving metal layer is provided. Although provided, an optical component similar to the optical component according to the second embodiment may be provided. That is, an optical component in which a chromium layer as a high reflectance metal layer is formed on the surface of the light irradiation surface and a silicon dioxide layer as an antioxidant layer is formed on the surface of the chromium layer may be provided. The high reflectivity metal layer may be a layer made of at least one of chromium, molybdenum, tungsten, aluminum, silicon, and germanium, and the anti-oxidation layer may be chromium oxide, molybdenum oxide, tungsten oxide, aluminum oxide. Any layer of at least one of silicon dioxide and titanium oxide may be used.

  An optical component having a chromium layer on the surface of quartz glass (base glass) and a platinum layer on the surface of the chromium layer was manufactured.

  That is, the surface of the light-irradiated surface of the optical component (quartz glass) on which the film is formed is highly cleaned by cleaning it with an automatic cleaning device that irradiates ultrasonic waves or by wiping with a cloth soaked in alcohol. Washed cleanly.

  Next, chromium (Cr) as an adhesion improving metal layer for improving the adhesion between the noble metal layer and the light irradiation surface of quartz glass (base glass) using a vacuum deposition film forming apparatus or a sputtering film forming apparatus. The layer was formed to a thickness of about 1 nm on the light irradiation surface of quartz glass. Since this chromium layer is an intermediate layer for improving adhesion, it may be thicker than 1 nm.

  Next, a platinum (Pt) layer as a noble metal layer having a high light reflectance is deposited on the surface of the chromium layer formed on the light-irradiated surface of quartz glass by using a vacuum deposition film forming apparatus or a sputtering film forming apparatus. The film was formed with a film thickness. In order to ensure a high light reflectivity, this platinum layer preferably has a film thickness that is not transparent, that is, thicker than 80 nm.

  An optical component having a high reflectance metal layer (chromium layer, tungsten layer or molybdenum layer) on the surface of quartz glass (base glass) and a silicon dioxide layer on the surface of the high reflectance metal layer was produced.

  That is, the surface of the light-irradiated surface of the optical component (quartz glass) on which the film is formed is highly cleaned by cleaning it with an automatic cleaning device that irradiates ultrasonic waves or by wiping with a cloth soaked in alcohol. Washed cleanly.

  Next, a chromium (Cr) layer, a tungsten (W) layer, a molybdenum (Mo) layer, or the like as a high reflectivity metal layer is formed on the light irradiation surface of quartz glass by using a vacuum deposition film forming apparatus or a sputtering film forming apparatus. The film was formed to a thickness of 85 nm.

Next, the surface of the high reflectivity metal layer formed on the light-irradiated surface of quartz glass is oxidized on the surface of the high reflectivity metal layer using a spin coating wet deposition method as an antioxidant layer for preventing oxidation of the high reflectivity metal layer. A silicon (SiO ₂ ) layer was formed to a thickness of about 30 nm. That is, a commercially available sol-gel silica liquid for wet film formation was uniformly applied at a substrate rotation speed of 1000 to 2000 rotations / minute, fired, and allowed to cool naturally.

Comparative example

  An optical component as a conventional example was manufactured. That is, the surface of the light-irradiated surface of the optical component (quartz glass) on which the film is formed is highly cleaned by cleaning it with an automatic cleaning device that irradiates ultrasonic waves or by wiping with a cloth soaked in alcohol. Washed cleanly.

Next, a chromium (Cr) layer having a high reflectivity was deposited on a light irradiation surface of quartz glass to a thickness of 85 nm by using a vacuum deposition film forming apparatus or a sputtering film forming apparatus.
(UV oxidation test)
About the above-mentioned Examples 1 and 2 and the comparative example, the ultraviolet oxidation test which irradiates a xenon excimer lamp (emission wavelength 172nm, about 40mW / cm < ² >) for 22 hours was done. Pure nitrogen is filled between the irradiated sample substrate surface and the lamp, and the oxygen concentration is controlled to be 0.1% or less. Since a very small amount of ozone is generated, oxidation of the sample substrate surface is promoted by active oxygen generated when ultraviolet rays and ozone are decomposed. Whether or not the sample substrate surface was oxidized was determined by measuring the reflectance at a wavelength of 190 to 900 nm using a spectral reflectance measuring device.
(Test results)
FIG. 9 is a graph showing the light reflectance at a wavelength of 190 to 900 nm on the surface of the optical component according to the first example. FIG. 10 is a graph showing the light reflectance of the surface of the optical component according to Example 2 at a wavelength of 190 to 900 nm. FIG. 11 is a graph showing the light reflectance at a wavelength of 190 to 900 nm on the surface of the optical component according to the comparative example. 9 to 11, the solid line represents the optical reflectance of the optical component before irradiation with the ultraviolet laser beam, the chain line represents the optical reflectance of the optical component after 12 hours have passed after irradiation with the ultraviolet laser beam, and the alternate long and short dash line represents the ultraviolet laser. The light reflectivities of the optical components after 22 hours from the irradiation of light are shown. Table 1 shows the light reflectivity at the KrF excimer laser wavelength and the light reflectivity at the ArF excimer laser wavelength on the surfaces of the optical components according to Example 1, Example 2, and Comparative Example.
(Table 1)
248 nm (KrF) 193 nm (ArF)
Example 1 Reflectance 3% decrease Reflectivity 0.3% increase Example 2 Reflectivity 4% decrease Reflectivity 6% decrease Comparative Example Reflectivity 35% decrease Reflectivity 32% decrease As apparent from this test result, comparison The light-irradiated surface of the optical component according to the example has a remarkable decrease in reflectance due to ultraviolet irradiation, but the light-irradiated surface of the optical component according to Examples 1 and 2 hardly caused a change in reflectance due to ultraviolet irradiation.

It is a figure which shows schematic structure of the projection exposure apparatus concerning 1st Embodiment. It is a figure which shows the positional relationship of the front-end | tip part of the optical component mounted on the Z stage concerning 1st Embodiment, and the optical element of a projection optical system. It is a figure which shows schematic structure of the fiducial mark concerning 1st Embodiment. It is a figure which shows schematic structure of the projection exposure apparatus concerning 2nd Embodiment. It is a figure which shows the positional relationship between the optical component mounted on the Z stage concerning 2nd Embodiment, the front-end | tip part of the optical element of a projection optical system, the discharge nozzle for X directions, and an inflow nozzle. It is a figure which shows the positional relationship of the front-end | tip part of the optical element of the projection optical system concerning 2nd Embodiment, and the discharge nozzle and inflow nozzle which supply and collect | recover the liquid from a Y direction. It is an enlarged view of the principal part which shows the mode of supply and collection | recovery of the liquid between the optical element concerning 2nd Embodiment, and a wafer. It is a figure which shows schematic structure of the fiducial mark concerning 2nd Embodiment. 3 is a graph showing light reflectance at a wavelength of 190 to 900 nm on the surface of the optical component according to Example 1; It is a graph which shows the light reflectivity in the wavelength of 190-900 nm of the surface of the optical component concerning Example 2. FIG. It is a graph which shows the light reflectivity in the wavelength of 190-900 nm of the surface of the optical component concerning a comparative example.

Explanation of symbols

  R ... reticle, PL ... projection optical system, W ... wafer, RM ... reticle mark, RAL ... reticle alignment system, WAL ... wafer alignment system, 1 ... illumination optical system, 4 ... optical element, 5 ... liquid supply device, 6 ... Liquid recovery device, 7 ... liquid, 9 ... Z stage, 10 ... XY stage, 14 ... main control system, 21, 22 ... supply pipe, 23, 24 ... recovery pipe, 56, 560 ... fiducial mark.

Claims (11)

An optical component mounted on the substrate stage of a projection exposure apparatus that illuminates a mask with an exposure beam and transfers the pattern of the mask onto a substrate held on the substrate stage via a projection optical system,
A light irradiation surface irradiated by the exposure beam; and an adhesion improving metal layer formed on a surface of the light irradiation surface;
An optical component comprising: a noble metal layer formed on a surface of the adhesion improving metal layer.   The optical component according to claim 1, wherein the adhesion improving metal layer is made of at least one of chromium, molybdenum, tungsten, aluminum, silicon, germanium, and titanium.   The optical component according to claim 1, wherein the noble metal layer is formed of at least one of gold, platinum, palladium, rhodium, iridium, and ruthenium.   The optical component according to any one of claims 1 to 3, wherein at least one of the adhesion improving metal layer and the noble metal layer is formed by vapor deposition or sputtering. An optical component mounted on the substrate stage of a projection exposure apparatus that illuminates a mask with an exposure beam and transfers the pattern of the mask onto a substrate held on the substrate stage via a projection optical system,
A light irradiation surface irradiated with the exposure beam; a high reflectance metal layer formed on a surface of the light irradiation surface;
An optical component comprising: an anti-oxidation layer that prevents oxidation of the high reflectivity metal layer formed on the surface of the high reflectivity metal layer.   6. The optical component according to claim 5, wherein the high reflectivity metal layer is formed of at least one of chromium, molybdenum, tungsten, aluminum, silicon, and germanium.   The optical component according to claim 5 or 6, wherein the antioxidant layer is formed of at least one of chromium oxide, molybdenum oxide, tungsten oxide, aluminum oxide, silicon dioxide, and titanium oxide.   8. The optical component according to claim 5, wherein at least one of the high reflectance metal layer and the antioxidant layer is formed by vapor deposition or sputtering.   The optical component according to any one of claims 1 to 8, wherein the light irradiation surface includes a base glass. A projection exposure apparatus that illuminates a mask with an exposure beam and transfers a pattern of the mask onto a substrate held on a substrate stage via a projection optical system,
A projection exposure apparatus comprising the optical component according to any one of claims 1 to 9 on the substrate stage.   11. The projection exposure apparatus according to claim 10, wherein a predetermined liquid is interposed between the surface of the substrate and the optical component on the substrate side of the projection optical system.

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