JP3997245B2 - Exposure apparatus and device manufacturing method - Google Patents

Description

  The present invention includes a projection optical system that projects an original pattern onto a substrate, and exposes the substrate through the original in a state where a liquid is filled in a gap between the substrate and the final surface of the projection optical system. The present invention relates to an apparatus and method, and a device manufacturing method using the exposure apparatus.

  In a manufacturing process of a semiconductor device composed of an ultrafine pattern such as LSI or VLSI, a reduction type projection exposure apparatus that transfers a pattern formed on a mask by reducing projection onto a substrate coated with a photosensitive agent is used. ing. As the integration density of semiconductor devices has increased, further miniaturization of patterns has been demanded, and at the same time as the development of resist processes, the miniaturization of exposure apparatuses has been addressed.

  As means for improving the resolving power of the exposure apparatus, a method of shortening the exposure wavelength and a method of increasing the numerical aperture (NA) of the projection optical system are generally used.

  The exposure wavelength is shifting from i-line at 365 nm to KrF excimer laser light having an oscillation wavelength near 248 nm, and further development of an ArF excimer laser having an oscillation wavelength near 193 nm is in progress. Further, a fluorine (F2) excimer laser having an oscillation wavelength near 157 nm has been developed.

  On the other hand, a projection exposure method using an immersion method is attracting attention as a technique for improving resolution, which is completely different from these. Conventionally, the space between the final surface of the projection optical system and the exposure target substrate (for example, wafer) surface has been filled with gas, but in the immersion method, this space is filled with liquid to perform projection exposure. The advantage of the immersion method is, for example, that the liquid provided in the space between the projection optical system and the wafer is pure water (refractive index 1.33), and the maximum incident angle of the light beam that forms an image on the wafer is higher than that of the conventional immersion method. Assuming that the method is equal, the resolution of the immersion method is improved 1.33 times that of the conventional method even when a light source having the same wavelength is used. This is equivalent to increasing the NA of the projection optical system of the conventional method by 1.33 times. According to the immersion method, it is possible to obtain a resolution of NA = 1 or higher, which is impossible with the conventional method.

  As a method for filling the space between the final surface of the projection optical system and the wafer surface with a liquid, two methods are roughly classified.

  One method is a method in which the final surface of the projection optical system and the entire wafer are arranged in a liquid tank, and an exposure apparatus using this method is disclosed in Patent Document 1.

The other is a local fill method in which a liquid is allowed to flow only in a space sandwiched between the projection optical system and the wafer surface. An exposure apparatus using this method is disclosed in Patent Document 2.
Japanese Patent Laid-Open No. 06-124873 Republished patent WO99 / 49504

  In the method disclosed in Patent Document 1, when the wafer is moved at a high speed, the liquid scatters to the surroundings. Therefore, a device for recovering the liquid is necessary, and minute bubbles that may be generated due to the rippling liquid surface are generated. There is a drawback of adversely affecting the imaging performance. In addition, this method is considered to increase the complexity and size of the apparatus.

  On the other hand, in the method disclosed in Patent Document 2, when the gap between the wafer and the projection optical system is narrow, even if the liquid is supplied by directing the nozzle to this gap, the liquid discharged from the nozzle flows into this gap well. There was a problem that the gas remained, and sufficient immersion was not possible. In addition, the liquid that does not flow well collides with the projection lens outer periphery and escapes to the outside, and it is necessary to provide equipment for recovering the liquid that has escaped around the projection lens, resulting in a large exposure apparatus. . Even if the liquid can be poured into a narrow gap, the flow velocity of the liquid discharged from the nozzle is very high compared with the flow velocity flowing through the gap because the flow resistance inside the gap is larger than the outside. . Accordingly, the flow velocity of the liquid changes drastically at the nozzle tip or at the location where the liquid collides with the outer periphery of the projection lens, the flow is greatly disturbed, and bubbles can be generated. This bubble can enter between the projection lens and the wafer, preventing light from passing therethrough and adversely affecting the imaging performance of the exposure apparatus.

  Furthermore, in the method disclosed in Patent Document 2, it is necessary to recover the liquid supplied onto the wafer at least every time the wafer is replaced, and the productivity of the apparatus must be sacrificed for the recovery of this liquid. I didn't get it. In addition, recovering the liquid on the wafer means recovering the liquid filled on the lower surface of the projection lens. Therefore, the lower surface of the projection lens can be in a state where at least every time the wafer is replaced, a part is wetted with a droplet, the other part is covered with a thin liquid film, and the other part is in direct contact with the outside air. . Compared with the supplied liquid, there are more impurities in the environment surrounding the projection lens and the wafer, and the liquid adhering to the surface of the lower surface of the projection lens is contained in the outside air. Will be taken in. On the other hand, since the liquid itself adhering to the lower surface of the projection lens evaporates toward the outside air, the impurities originally contained in the liquid and the impurities taken in from the outside air are gradually concentrated in the liquid, and as a result, the projection lens surface There is a possibility that impurities are adsorbed on the surface of the projection lens to cause fogging, or the liquid is completely evaporated and dried to leave impurities as residues on the projection lens surface to cause fogging.

  An object of the present invention is to enable illuminance measurement in a state where the final surface of the projection optical system is immersed while suppressing a decrease in productivity.

According to a first aspect of the present invention, there is provided a projection optical system that projects an original pattern onto a substrate, and the substrate is exposed with a liquid filled in a gap between the final surface of the projection optical system and the substrate. An exposure apparatus that is movable with respect to the projection optical system and that holds the substrate; an upper surface of the substrate that is movable with respect to the projection optical system and is held on the substrate stage; a flat plate having an upper surface of substantially the same height, and a supply means for supplying the liquid to the gap, and a recovery means for recovering the liquid from the gap, provided on the flat plate, through the liquid And a sensor for receiving exposure light .

According to a second aspect of the present invention, there is provided a projection optical system that projects an original pattern onto a substrate, and the substrate is exposed with a liquid filled in a gap between the final surface of the projection optical system and the substrate. An exposure apparatus that is movable with respect to the projection optical system and that holds the substrate, and is substantially the same as the upper surface of the substrate that is disposed on the substrate stage and held on the substrate stage A flat plate having an upper surface at a height; supply means for supplying the liquid to the gap; recovery means for recovering the liquid from the gap; and receiving light for exposure via the liquid. And a sensor that performs the operation.

According to a third aspect of the present invention, there is provided a projection optical system that projects an original pattern onto a substrate, and the substrate is exposed with a liquid filled in a gap between the final surface of the projection optical system and the substrate. An exposure apparatus that is movable with respect to the projection optical system, is capable of moving with respect to the projection optical system independently of the substrate stage that holds the substrate, and the substrate stage. And a sensor for receiving exposure light.

  According to the present invention, it is possible to perform illuminance measurement in a state where the final surface of the projection optical system is immersed while suppressing a decrease in productivity.

  The exposure apparatus of the present invention is useful, for example, in any exposure method and exposure apparatus to which an immersion method is used in which ultraviolet light is used as exposure light and a space between a projection optical system and a substrate (for example, a wafer) is filled with liquid. Such an exposure apparatus includes, for example, an exposure apparatus that projects and transfers an original pattern onto the substrate while the substrate is stationary, and slits the original pattern onto the substrate while synchronously scanning the substrate and the original. An exposure apparatus that performs scanning exposure can be included.

  Hereinafter, preferred embodiments of the present invention will be exemplarily described. FIG. 1 is a diagram schematically showing a configuration of a preferred embodiment of the present invention. In FIG. 1, light emitted from an exposure light source (not shown) such as an ArF excimer laser or F2 laser is provided to the illumination optical system 2. The illumination optical system 2 illuminates a part of the reticle (original) 1 with slit light (light having a cross-sectional shape that passes through the slit) using light provided from an exposure light source. While the reticle 1 is illuminated by the slit light, one of the reticle stage (original stage) 3 holding the reticle 1 and the wafer stage (substrate stage) 10 holding the wafer (substrate) 9 is set to the other. Move the scan while synchronizing. Through such a synchronous scan, as a result, the entire pattern on the reticle 1 is continuously imaged on the wafer 9 via the projection optical system 4, and the resist applied to the surface of the wafer 9 is exposed.

  The two-dimensional positions of reticle stage 3 and wafer stage 10 are measured in real time by reference mirror 11 and laser interferometer 12. Based on this measurement value, the stage control device 13 performs positioning and synchronous control of the reticle 1 (reticle stage 3) and the wafer 9 (wafer stage 10). The wafer stage 10 has a built-in drive device that adjusts, changes or controls the position, rotation direction and tilt of the wafer 9 in the vertical direction (vertical direction). The wafer stage 10 is controlled so that the exposure area on the wafer 9 always matches the focal plane with high accuracy. Here, the position of the surface on the wafer 9 (vertical position and inclination) is measured by an optical focus sensor (not shown) and provided to the stage controller 13.

  The exposure apparatus main body is installed in an environmental chamber (not shown), and the environment surrounding the exposure apparatus main body is maintained at a predetermined temperature. The space surrounding the reticle stage 3, the wafer stage 10, and the interferometer 12 and the space surrounding the projection lens 4 are further blown with individually controlled temperature-controlled air to maintain the environmental temperature with higher accuracy.

  In this embodiment, the liquid immersion method for filling the space or gap between the projection optical system 4 and the wafer 9 with a liquid includes a liquid supply nozzle 5 disposed above the wafer 9 and in the vicinity of the projection optical system 4, and a projection. This is realized by the liquid recovery nozzle 6 disposed on the opposite side of the liquid supply nozzle 5 with the optical system 4 interposed therebetween.

  Hereinafter, the liquid immersion method performed in this embodiment will be described in detail. A liquid supply nozzle 5 is arranged in the vicinity of the projection optical system 4 on the upstream side in the scanning direction of the wafer 9 during exposure. Here, the upstream side in the scanning direction is, for example, the right side which is the opposite direction (first direction) when the wafer is moved leftward (second direction) from right to left. That is, when the scan direction (second direction) is indicated by an arrow, the direction on the start point side (first direction) of the arrow is the upstream side. A liquid recovery nozzle 6 is disposed on the opposite side of the liquid supply nozzle 5 (that is, downstream in the scanning direction) with the projection optical system 4 interposed therebetween.

  The liquid supply nozzle 5 is connected to the liquid supply device 7 via a supply pipe 16, and similarly, the liquid recovery nozzle 6 is connected to the liquid recovery apparatus 8 via a recovery pipe 17. The liquid supply device 7 can include, for example, a tank that stores liquid, a pressure-feed device that sends out liquid, and a flow rate control device that controls the supply flow rate of liquid. The liquid supply device 7 preferably further includes a temperature control device for controlling the supply temperature of the liquid. The liquid recovery device 8 can include, for example, a tank that temporarily stores the recovered liquid, a suction device that sucks the liquid, and a flow rate control device for controlling the liquid recovery flow rate. The liquid immersion control device 18 further receives information such as the current position, speed, acceleration, target position, and movement direction of the wafer stage 10 from the stage control device 13 and starts or stops liquid immersion based on these information. A control command such as a flow rate is given to the liquid supply device 7 and the liquid recovery device 8.

  The liquid for immersion is selected from those that absorb less exposure light, and it is desirable that the liquid has a refractive index substantially the same as that of a refractive optical element such as quartz or fluorite. Specifically, as the liquid for immersion, pure water, functional water, fluorinated liquid (for example, fluorocarbon) and the like are listed as candidates. The liquid for immersion is preferably a liquid from which dissolved gas has been sufficiently removed in advance using a deaeration device. This is because the generation of bubbles is suppressed, and even if bubbles are generated, they can be immediately absorbed into the liquid. For example, the generation of bubbles can be sufficiently suppressed if 80% or more of the amount of gas that can be dissolved in the liquid is removed, targeting nitrogen and oxygen contained in a large amount in the environmental gas. Of course, a degassing device (not shown) may be provided in the exposure apparatus, and the liquid may be supplied to the liquid supply device 7 while always removing the dissolved gas in the liquid. As the degassing device, for example, a vacuum degassing device in which a liquid is allowed to flow on one side across a gas permeable membrane and the other is evacuated to drive out dissolved gas in the liquid to the vacuum through the membrane is suitable. It is.

  Next, a process of filling the liquid between the projection optical system 4 and the wafer 9 will be described with reference to FIG.

  First, while the wafer 9 is stationary or moving, the liquid f is supplied from the liquid supply nozzle 5 onto the wafer 9 at a substantially constant flow rate, for example, and the liquid is supplied to the lower surface of the liquid supply nozzle 5 and the upper surface of the wafer 9. By adhering, a sufficient liquid film is formed (FIG. 2A).

  Next, while the liquid is continuously supplied from the supply nozzle 5, the movement of the wafer 9 is started or further moved, and the movement of the wafer 9 is performed without interrupting the liquid film formed in (FIG. 2A). Utilizing this, the liquid film is guided to the lower surface of the projection optical system 4 (FIGS. 2B and 2C).

  When the wafer 9 further moves and reaches the exposure start position, scan exposure using slit light is started (FIG. 2D). Even during the slit exposure, as in FIG. 2C, the liquid continues to be supplied from the supply nozzle 5, and further flows out from the downstream side (left side in FIG. 2) in the scanning direction S with respect to the projection optical system 4. By recovering the liquid with the recovery nozzle 6, the space between the wafer 9 and the projection optical system 4 is stably filled with the liquid (FIG. 2D).

  When the wafer 9 further moves and reaches the exposure end position, the exposure with the slit light is completed (e). When the exposure with the slit light is completed, the supply of the liquid from the liquid supply nozzle 5 is stopped (FIG. 2E), and the liquid remaining on the wafer 9 is removed from the liquid recovery nozzle while moving the wafer 9 in the scanning direction S. 9 (FIG. 2 (f), FIG. 2 (g)).

  As described above, according to the method of continuously supplying the liquid onto the surface of the wafer 9 while moving the wafer 9 so that the liquid film spreads as the wafer 9 moves, the final surface of the projection optical system 4 is obtained. And the wafer 9 can be filled with a continuous liquid film (an uninterrupted liquid film). According to such a method, compared with the method described in Patent Document 2 in which the nozzle is directed to the gap between the projection optical system 4 and the wafer 9 and liquid is supplied to the gap, the projection optical system, the wafer, Even when the gap is small, a liquid film can be reliably formed in the gap, and bubbles that may exist in the liquid film can be reduced. Also, according to such a method, the liquid film can be reliably recovered through the liquid recovery nozzle 6 since the relative speed with respect to the wafer is low. Therefore, scattering of the liquid to the outside can be effectively prevented.

  The liquid supply / recovery sequence as described above may be performed for each exposure shot area (each transfer of the reticle image), or all or a part of the exposure shot area on the wafer may be used as one unit. May be implemented. In the latter case, liquid supply and recovery may be performed even when the wafer is moved stepwise between exposure shot regions, and liquid supply and recovery may be stopped during the step movement.

  The liquid immersion as described above can also be applied to an exposure apparatus (a so-called stepper or the like) that performs exposure while the wafer is stationary. In this case, for example, when the wafer is stepped between the exposure shot areas, the liquid is supplied and recovered so as to spread the liquid film between the exposure shot area to be exposed next and the lower surface of the projection optical system 4. Control is sufficient.

  Next, a preferred example of specific configurations and arrangements of the liquid supply nozzle 5 and the liquid recovery nozzle 6 will be described with reference to FIGS.

  FIG. 3 is a plan view of the exposure apparatus of FIG. 1 cut above the wafer 9 and looking down. The liquid supply nozzle 5 is located upstream of the movement direction S of the wafer 9 (+ X direction as viewed from the projection optical system 4) (−X direction as viewed from the projection optical system 4) across the final surface 4s of the projection optical system 4. The liquid recovery nozzle 6 is disposed downstream (in the + X direction as viewed from the projection optical system 4). When the exposure apparatus is a scanner (scanning exposure apparatus), it is desirable that the wafer movement direction be the same as the wafer scanning direction during exposure in order to stably form a liquid film.

  The liquid supply nozzle 5 is preferably arranged so that its lower surface (lower end) is substantially the same height as or slightly higher than the final surface (lower surface) 4 s of the projection optical system 4, thereby eliminating the air layer. However, the liquid can move with the wafer while being in close contact with the final surface of the projection lens 4, and bubbles can be prevented from being mixed into the liquid film.

  The liquid recovery nozzle 6 is preferably arranged so that its lower surface (lower end) is substantially the same height as or slightly lower than the final surface (lower surface) 4 s of the projection optical system 4. The liquid on the wafer can be efficiently recovered.

  The total length L1 of the liquid supply nozzle 5 outlet for discharging the liquid is preferably at least equal to or longer than the length Le of the region through which the exposure light beam passes, and equal to or greater than the width of the final surface 4s of the projection optical system 4. Longer is more preferable. The length L2 of the liquid recovery nozzle 6 is preferably equal to or longer than the length L1 of the liquid discharge port of the liquid supply nozzle 5, and further preferably equal to or longer than the width of the final surface 4s of the projection optical system. preferable.

  The flow rate V of the liquid supplied from the supply nozzle 5 to the space (immersion space) between the wafer 9 and the lower surface of the projection optical system 4 is preferably determined according to the equation (1).

V ≧ L1 · d · υ Formula (1)
Here, d is the interval between the portions filled with the liquid between the wafer and the final surface (lower surface) of the projection optical system. υ is the moving speed of the wafer during immersion, and the scanning speed of the wafer is applied during scanning exposure.

  Further, the flow rate V of the liquid supplied from the liquid supply nozzle 5 to the immersion space is expressed by Expression (2), where μ is the average liquid flow velocity at the liquid discharge port of the supply nozzle 5.

V = L1 · w · μ (2)
Here, w is the width of the liquid discharge port. Equation (3) is derived from Equation (1) and Equation (2).

μ ≧ d · υ / w... Formula (3)
That is, more generally, the average liquid flow velocity at the liquid discharge port of the supply nozzle 5 (that is, the supply flow rate per unit area of the discharge port) is the gap distance d between the projection optical system final surface 4s and the wafer 9 and the wafer. The flow rate of the liquid to be supplied may be determined so as to be equal to or greater than the value obtained by dividing the product of the moving speed υ of the stage 10 by the width w of the discharge port. Here, when w is strictly defined, the minimum value of the width of the liquid discharge port along the moving direction of the wafer 9 in the corresponding liquid supply nozzle 5 is obtained.

In order to be able to start exposure from the edge of the wafer, the final surface (lower surface) 4s of the projection optical system 4 before the edge of the wafer reaches the exposure area (area irradiated with exposure light). It is necessary to grow a liquid film underneath. Therefore, in the configuration example shown in FIG. 3, the same surface plate (planar plate) 19 having substantially the same height as the wafer 9 is provided on the outside of the wafer 9, so that the liquid is also formed in the region outside the wafer 9. It is possible to form a film.

  FIG. 4 is a diagram illustrating a second configuration example regarding the configuration and arrangement of the liquid supply nozzle 5 and the liquid recovery nozzle 6. The second configuration example shown in FIG. 4 is illustrated in that the openings of the liquid supply nozzle 5 and the liquid recovery nozzle 6 are provided within the surfaces of the continuous members 20a and 20b (the wafer stage or the surface facing the wafer). 3 is different from the first configuration example shown in FIG.

  The bottom surfaces (opposing surfaces) of the continuous members 20a and 20b are substantially the same height as the final surface 4s of the projection optical system. Further, the outer peripheral end of the projection optical system final surface 4 s is disposed so as to be in close contact with the outer peripheral portion of the lens barrel of the projection optical system 4. According to such a configuration, the distance between the wafer 9 and the bottom surface of the liquid supply nozzle 5, the distance between the wafer 9 and the bottom surface of the liquid recovery nozzle 6, and the distance between the wafer 9 and the final surface of the projection optical system 4s are substantially the same. Further, the bottom surface of the liquid supply nozzle 5, the final surface 4s of the projection optical system, and the bottom surface of the liquid recovery nozzle 6 can be configured as a continuous surface.

  The configuration in which the nozzles 5 and 6 are arranged in a plane continuous from the final surface 4s of the projection optical system has the following advantages. The liquid supplied from the liquid supply nozzle 5 is in close contact with the bottom surface of the continuous member 20a opened by the liquid supply nozzle 5 and the wafer 9 to form a liquid film. The liquid film advances together with the wafer 9 toward the final surface 4s of the projection optical system continuously connected to the bottom surface of the continuous member 20a. Therefore, this liquid film can smoothly enter the final surface 4s of the projection optical system 4 and further the bottom surface of the continuous member 20b. As described above, the projection optical system final surface 4s and the continuous members 20a and 20b connected to the final surface 4s make it possible to fill almost the entire gap between them and the wafer 9 with the liquid.

  Further, since the liquid film always moves with the wafer 9 while its upper and lower surfaces are in close contact with the flat surface, the contact with the environment (gas) surrounding the liquid film is substantially only on the side surface of the liquid film. Accordingly, the contact area between the liquid film and the gas is small, and the liquid film flows through a substantially constant gap, so that the speed change is small and the flow is not easily disturbed, and bubbles are not easily generated in the liquid film. In addition, this reduces the dissolution of the gas in the liquid, so that it is possible to suppress the generation of microbubbles in the liquid film due to temperature and local pressure changes.

  As long as the bottom surface (lower surface) of the continuous members 20a and 20b is continuous with the final surface (lower surface) 4s of the projection optical system 4, it may have a thin plate shape, a block shape, or the like. You may have the shape of. Further, the continuous members 20 a and 20 b may be configured as a part integrated with the bottom surfaces of the nozzles 5 and 6 and / or the bottom surface of the lens barrel of the projection optical system 4.

  FIG. 5 is a diagram showing a third configuration example regarding the configuration and arrangement of the liquid supply nozzle 5 and the liquid recovery nozzle 6. The third configuration example shown in FIG. 5 is that both the liquid supply nozzle 5 (5a, 5b) and the liquid recovery nozzle 6 (6a, 6b) are arranged on both sides of the projection optical system final surface 4s. 4 is different from the second configuration example shown in FIG.

  The liquid supply nozzles 5 a and 5 b are disposed so as to sandwich the projection optical system 4 at a position relatively close to the final surface 4 s of the projection optical system 4, and the liquid recovery nozzles 6 a and 6 b are relatively relative to the projection optical system 4. It can be arranged at a position far from the final surface 4s, that is, outside the liquid supply nozzles 5a and 5b.

  When the wafer 9 is moving in the + X direction of the arrow shown in FIG. 5, the liquid is supplied from the liquid supply nozzle 5a to the gap between the wafer 9 and the final surface 4s, and the supply from the liquid supply nozzle 5b is stopped. At this time, most of the liquid can be recovered by the liquid recovery nozzle 6b. However, depending on the flow rate of the liquid supplied from the liquid supply nozzle 5a, the liquid may flow in the opposite direction. Accordingly, by operating the liquid recovery nozzle 6a in addition to the liquid recovery nozzle 6b and recovering the liquid flowing in the reverse direction, it is possible to prevent the liquid from scattering and spilling. In consideration of such an effect, the liquid recovery nozzle is preferably arranged on the entire circumference so as to surround the periphery of the projection optical system final surface 4s, and the liquid is always recovered when the liquid is supplied from the liquid supply nozzle. It is preferable to operate the nozzle.

  On the other hand, when the wafer 9 is moving in the −X direction of the arrow shown in FIG. 5, contrary to the above, the liquid is supplied from the liquid supply nozzle 5b and the supply of the liquid from 5a is stopped. Thus, the gap between the wafer 9 and the projection lens final surface 4s can always be filled with the liquid regardless of whether the wafer moving direction is normal or reverse. Further, by switching the supply of liquid from both nozzles 5a and 5b, the liquid film is projected without being interrupted (without separating the liquid film) even when the moving direction of the wafer is reversed. The gap with the lens final surface 4s can be filled with the liquid.

  The shape of the final projection lens surface 4s need not be circular. For example, if the portion facing the nozzle is a straight line, for example, a bowl shape as shown in FIG. 5, the liquid supply nozzles 5a and 5b and the liquid recovery nozzles 6a and 6b can be brought closer to the optical path of the exposure light beam. As a result, the time required to fill the liquid and the wafer moving distance can be reduced. In particular, in the case of a scanner, the exposure light beam has a slit shape on the wafer surface, and a light beam having a cross-sectional shape that is short in the scanning direction and long in the direction perpendicular to the scanning direction is used also on the projection lens final surface 4s adjacent thereto. Therefore, the shape of the final surface of the projection optical system 4 can be changed to a shape such as a saddle with a narrow width in the scanning direction according to the cross-sectional shape of the light beam. Of course, the shape of the final surface of the projection optical system is not limited to the saddle shape, and may be various shapes such as a rectangular shape or a circular arc shape (a part of an annular shape).

  FIG. 6 is a diagram illustrating a fourth configuration example relating to the configuration and arrangement of the liquid supply nozzle and the liquid recovery nozzle. In the fourth configuration example shown in FIG. 6, the liquid supply nozzles 5a to 5d are provided on the four sides surrounding the projection optical system final surface 4s, respectively, and the liquid recovery nozzles 6a to 6d are provided so as to surround the outer periphery thereof. ing. When the wafer moves in the arrow + X direction in the figure, the liquid is supplied from the liquid supply nozzle 5a provided on the upstream side in the wafer movement direction, and when the wafer moves in the arrow -X direction, the liquid supply nozzle 5b. Supply more liquid. When the wafer moves in the arrow + Y direction, liquid is supplied from the supply nozzle 5c. When the wafer moves in the arrow -Y direction, liquid is supplied from the liquid supply nozzle 5d.

  Since the liquid is mostly collected by the liquid recovery nozzle disposed on the downstream side in the wafer movement direction, only the target recovery nozzle may be operated. However, in preparation for unforeseen circumstances such as malfunctions, the liquid recovery nozzles 6a to 6c are more likely to scatter and spill liquids if all four of them are operated simultaneously at least while supplying the liquid. Can be prevented. Of course, instead of arranging a plurality of liquid recovery nozzles, a single liquid recovery nozzle may be arranged over the entire circumference so as to surround the periphery of the projection optical system final surface 4s. What is necessary is just to determine the flow volume of the liquid supplied from the liquid supply nozzles 6a-6c according to Formula (3). According to the above configuration, the moving direction of the wafer is not limited to the X and Y directions, and the liquid film can be maintained even when moving in an oblique direction.

  As described above, the plurality of liquid supply nozzles are arranged so as to surround the final surface 4s of the projection optical system, and are further arranged upstream in the movement direction (on the opposite side of the movement direction as viewed from the projection optical system) when the wafer is moved. By switching the liquid supply nozzle used for supply so that the liquid is supplied from the liquid supply nozzle, it is possible to always fill the gap between the final surface of the projection optical system 4s and the wafer with the liquid regardless of the moving direction of the wafer. It becomes. As a result, not only during scanning exposure but also during step movement within the wafer surface and when changing the movement direction of the wafer, the liquid film between the wafer 9 and the projection lens final surface 4s is always liquid without interrupting the liquid film. Can be satisfied. Thereby, it is possible to always fill the gap between the projection optical system final surface 4s and the wafer 9 with the liquid without interrupting the liquid film from the start of exposure to the completion of the exposure of the entire wafer surface in one wafer. Become. As a result, it is not necessary to form a liquid film for each shot, and the productivity of the exposure apparatus is greatly improved.

  FIG. 7 is a diagram illustrating a fifth configuration example relating to the configuration and arrangement of the liquid supply nozzle and the liquid recovery nozzle. In this configuration example, the liquid supply nozzles 5a to 5h and the liquid recovery nozzles 6a to 6h are arranged on the circumference so as to surround the outer periphery of the projection optical system final surface 4s. The liquid supply nozzle is disposed inside the liquid recovery nozzle. As described above, by arranging the nozzles on the circumference, even when the wafer stage 10 moves obliquely, the liquid is supplied from the liquid supply nozzle substantially corresponding to the upstream in the moving direction, and at least downstream in the moving direction. By recovering the liquid from the liquid recovery nozzle located at, the gap between the final surface of the projection optical system and the wafer can be filled with the liquid.

  For example, when the wafer moves at an angle of 45 ° in the + X and + Y directions as indicated by arrows, the liquid is supplied from at least the liquid supply nozzles 5b and 5c and the liquid is recovered from at least the liquid recovery nozzles 6f and 6g. What is necessary is just to control each nozzle. Thus, by arranging each nozzle on the circumference, it becomes possible to form a liquid film more flexibly corresponding to various movement directions of the wafer. In FIG. 7, a plurality of divided liquid recovery nozzles are shown. However, in the same manner as described with respect to the fourth configuration example, the liquid recovery nozzles 6 a to 6 h are prepared in preparation for unexpected situations such as malfunctions. It is possible to more reliably prevent the liquid from being scattered or spilled by operating them all at least while supplying the liquid. Of course, instead of arranging a plurality of liquid recovery nozzles, a single liquid recovery nozzle may be arranged over the entire circumference so as to surround the periphery of the projection optical system final surface 4s.

  When the gap between the wafer and the projection lens final surface 4s is not filled with the liquid, or when the liquid is not completely filled and gas is still present in the gap, as described above, the movement direction of the wafer It is preferable to supply the liquid from the upstream side. However, after the gap between the wafer 9 and the projection lens final surface 4s is completely filled with the liquid, the liquid may be supplied from all the liquid supply nozzles regardless of the movement direction of the wafer. In this case, the flow rate of the liquid to be supplied and the recovery flow rate are increased and the running cost is increased. However, since it is not necessary to frequently switch the supply nozzle, the time required for the switching is eliminated, and the productivity of the exposure apparatus is reduced. improves. In addition, there is no need for a drive device that switches the supply nozzle at high speed, and there is an advantage that the liquid supply device can be miniaturized. Such control of liquid supply is not limited to the configuration example shown in FIG. 7, but can also be applied to the configuration of the nozzles shown in FIGS. 5 and 6. In this case, the same effect can be obtained. .

  In the configuration example shown in FIG. 7, the flow rate of the liquid supplied from the liquid supply nozzle may be basically determined by applying Expression (3) to each liquid supply nozzle. Moreover, this can be simplified and the liquid of the same flow rate can be supplied uniformly from all the liquid supply nozzles. In this case, in the configuration example shown in FIG. 7, since the shape of the discharge port of the liquid supply nozzle is arranged around the center of the exposure light beam, the width of the liquid supply port is increased regardless of the moving direction of the wafer. The total flow rate V ′ may be determined according to the equation (4) with the constant value w ′.

V ′ ≧ π · D · d · υ Equation (4)
Here, π is the circumference ratio, D is the average diameter of the discharge ports, d is the distance between the wafer and the final surface of the projection optical system, and υ is the moving speed of the wafer during immersion.

  Next, another preferred embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a plan view of the wafer stage 10 viewed from above the final surface 4s of the projection optical system and the nozzles provided around it. According to the original drawing method, the outlets of the nozzles 5 and 6 are provided so as to face the wafer 9, and therefore should be represented by hidden lines (broken lines) in the plan view seen from above. There is a solid line to make it easier to understand.

A flat plate 21 is provided adjacent to the wafer 9 adsorbed on the wafer stage 10. The flat plate 21 is arranged so that the upper surface thereof is substantially (substantially) the same as the upper surface of the wafer fixed on the wafer stage 10 by vacuum suction or the like. When the flat plate 21 is located directly under the projection optical system final surface 4s, the wafer 9 can be recovered from the wafer stage 10 and the wafer 9 can be placed on the wafer stage 10. A wafer transfer device (not shown) is arranged.

  The steps of this embodiment will be described with reference to FIG. FIG. 9 shows the behavior of each part in the order of steps using the cross-sectional view of the main part of FIG.

  During the exposure, the liquid is supplied from the liquid supply nozzle 5 as necessary, and the liquid is recovered by the liquid recovery nozzle 6, while the gap between the wafer 9 and the final surface 4s of the projection optical system is always filled with the liquid. It is maintained (FIG. 9 (a)). When a series of exposures on one wafer 9 is completed, the wafer stage 10 is moved so that the flat plate 21 adjacent to the wafer 9 is positioned immediately below the final surface 4s of the projection optical system (FIG. 9B). . When the wafer stage 10 is moved, liquid is supplied from the liquid supply nozzle 5 and liquid is continuously recovered from the liquid recovery nozzle 6, so that the plane plate 21 is positioned below the final surface 4 s of the projection optical system. The bottom surface of the projection optical system 4s is always filled with liquid. Next, while maintaining this state, the exposed wafer 9 attracted and fixed on the wafer stage 10 is recovered from the wafer stage 10 to a wafer storage unit (not shown). Further, a new wafer 9 ′ is placed on the wafer stage 10 and is fixed by suction (FIG. 9C).

  Then, the liquid is supplied from the liquid supply nozzle 5, the wafer stage 10 is moved while the liquid is recovered by the liquid recovery nozzle 6, and the wafer 9 ′ is projected while constantly filling the liquid below the final surface 4 s of the projection optical system. It is sent directly under the optical system final surface 4s (FIG. 9D).

  In this way, most of the liquid on the wafer can be recovered by moving the flat plate 21 to the exposure position while continuing to supply and recover the liquid even after the exposure is completed. Therefore, since the wafer can be exchanged smoothly without performing a special liquid recovery operation, the productivity of the exposure apparatus can be improved. Further, since the final surface 4s of the projection optical system is always filled with the liquid regardless of the exchange of the wafer, impurities contained in the environmental atmosphere do not directly touch the final surface 4s of the projection optical system. In addition, since the contact portion between the liquid and air is minimized, the amount of impurities taken into the liquid can be minimized. Therefore, fogging of the final surface 4s of the projection optical system due to impurities can be suppressed.

  On the other hand, when the liquid is collected each time the wafer is exchanged, the surface of the final surface 4s of the projection optical system is temporarily placed with a thin liquid film. When the liquid is pure water, inorganic components and hydrophilic organic components contained in the environment are easily taken into the pure water film, and when the pure water evaporates, the inorganic components and organic components are projected into the optical system. It is very likely to remain on the surface of the system and cause fogging.

  Further, as shown in FIGS. 9B and 9C, a liquid film is maintained between the final surface 4s of the projection optical system and the flat plate 21 while the wafer on the wafer stage 10 is being replaced. In this state, the liquid film has been exposed to exposure light in contact with the surface of the photosensitive agent coated on the wafer until just before this. When the photosensitive agent is exposed, more or less components contained in the photosensitive agent are released as gaseous substances, and the gaseous substances are dissolved in the liquid film in contact with the upper surface.

  Since the liquid film immediately after exposure is in a contaminated state in which this gaseous substance is dissolved, it is better to sufficiently replace the liquid film with a new liquid before the start of the next exposure. Otherwise, the transmittance in the liquid film is changed by the dissolved impurities, which adversely affects the exposure amount control, and there is a possibility that a problem of deteriorating the productivity of the exposure apparatus such as an increase in line width variation may occur. Furthermore, there is a concern that the dissolved impurities are supersaturated and generated as bubbles, resulting in poor imaging. Impurities dissolved in the liquid film may cause a chemical reaction due to the exposure light, which may cause fogging of the final surface of the projection optical system. Therefore, in the following, such a problem and its solution will be considered.

  If a new liquid is continuously supplied from the liquid supply nozzle 5 and is continuously recovered from the liquid recovery nozzle 6, even if the replacement speed is slow, the liquid film is replaced with a new liquid. Therefore, it is considered that the purity of the liquid film sufficient for the next exposure may be increased only by the supply and recovery by the nozzles 5 and 6 on the wafer 9 or the flat plate 21. Further, the purity of the liquid film can be further improved by increasing the flow rate of supply and recovery immediately after exposure and returning it to the original flow rate immediately before exposure. In this case, when the flow rate is changed, the wafer 9 and the flat plate 21 are moved, and the moving speed of the wafer 9 and the flat plate 21 is also changed in accordance with the change amount of the flow rate. If the liquid is supplied / recovered while reciprocating or rotating the wafer 9 or the flat plate 21, the liquid film can be continuously replaced.

  Such increase / decrease of the supply flow rate and the recovery flow rate may be performed for each shot region, may be performed for each wafer, or may be performed at different intervals and timings as necessary. . However, depending on the material of the photosensitizer used, outgassing occurs even in the unexposed state. Therefore, contamination may proceed only by contact of the liquid film on the photosensitizer. Some are very outgassing. Therefore, the liquid film may be more easily contaminated than expected.

  Therefore, as another method for more positively replacing the liquid film below the final surface of the projection optical system with a new liquid, a liquid suction port 22 may be provided at an appropriate position such as the center of the flat plate 21 as shown in FIG. Good. A suction device such as a suction pump or a cylinder (not shown) is connected to the suction port 22 and can suck a gas or a liquid. That is, as shown in FIG. 10, in a state where the flat plate 21 is sent directly under the final surface 4s of the projection optical system, the liquid is recovered from the suction port 22, and at the same time, the flow rate of the liquid supplied from the liquid supply nozzle 5 is set at least. The flow rate is increased by the same amount as the amount sucked from the suction port 22. As a result, most of the liquid film below the final surface of the projection optical system has a flow toward the central suction port 22 instead of the outer peripheral direction (direction of the liquid recovery nozzle 6), and even when the flat plate 21 is stationary, This liquid film can be continuously replaced with a new liquid (FIGS. 10B and 10C).

  With the above configuration, the liquid replacement speed under the final surface of the projection optical system is dramatically improved. In addition, since the liquid film is replaced on the flat plate 21 that can be applied with a material that is not easily contaminated chemically, such as stainless steel or fluororesin, and is easy to maintain cleanliness, not on a photosensitive agent that may be contaminated, the purity of the liquid film is very high. Can fill the gap below the final surface of the projection optical system. Therefore, it is possible to more effectively suppress the influence of impurities existing in the outside air and impurity gas components generated from the surface of the photosensitive agent on the final surface of the projection optical system.

  The replacement of the liquid film on the flat plate 21 as shown in FIG. 9 and FIG. 10 is not limited at the time of wafer replacement, and it may be regular or irregular even during a series of exposure sequences of one wafer. However, it can be implemented as necessary.

  In the configuration example shown in FIGS. 9 and 10, when the flat plate 21 is provided on the wafer stage and the wafer is transferred between the wafer stage and a wafer transfer device (not shown), the flat surface is directly below the final surface 4s of the projection optical system. The face plate 21 is located. However, the flat plate 21 performs various operations required before and after the exposure and various operations necessary for the maintenance and management of the exposure apparatus, for example, when performing an alignment measurement process using an off-axis microscope (not shown) performed before the exposure. Also when performing, you may comprise so that it may be located just under the projection optical system final surface. Here, when the plane plate 21 and the suction port 22 are required directly below the final surface of the projection optical system at the plurality of wafer stage positions, the plurality of plane plates and the suction port may be arranged on the wafer stage. Of course, like the same surface plate 19 shown in FIG. 3, a plane plate may be disposed so as to surround the wafer, and a plurality of suction ports are provided on the plane plate at the position of the final surface of the projection optical system when performing various processes. You may provide together.

9 and 10, the flat plate 21 is disposed on the wafer stage 10, but a dedicated driving device (not shown) is provided so that the flat plate 21 can be moved independently from the wafer stage 10. May be. However, in this case, the flat plate 21 should be driven so that a large gap is not formed between the flat plate 21 and the wafer fixed on the wafer stage 10. For example, when shifting from the state of FIG. 9A to the state of FIG. 9B or when shifting from the state of FIG. 9C to the state of FIG. It should be driven so as to move in the vicinity of the final surface of the projection optical system while cooperating so as to maintain the relationship. Here, at least while the gap between the wafer and the flat plate 21 passes directly under the final surface of the projection optical system, the height of the flat plate 21 should be maintained substantially (substantially) the same as the upper surface of the wafer. It is.

  After the liquid film is moved between the final surface of the projection optical system and the flat plate 21, the position of the flat plate 21 is maintained, and the position of the wafer stage 10 is arbitrarily changed to perform various processes. It can be carried out. By providing a mechanism for moving the flat plate 21 independently from the wafer stage 10 in this way, the final stage of the projection optical system is utilized by using the time interval in which the wafer stage 10 is used for various operations other than exposure. There is an advantage that the underside of the surface can be filled with liquid. Further, by providing such a mechanism, it is not necessary to provide a plurality of flat plates and suction ports or to enlarge the flat plate, so that the exposure apparatus can be reduced in size.

  An illuminance unevenness sensor for measuring the illuminance distribution of the exposure light and an absolute illuminometer for measuring the absolute illuminance of the exposure light may be provided at an appropriate location on the flat plate 21. In this case, it is possible to measure illuminance unevenness and absolute illuminance in the liquid immersion state almost the same as the exposure state while the liquid is continuously filled below the final surface of the projection optical system without collecting the liquid once. Thereby, it is possible to measure illuminance unevenness and absolute illuminance with high accuracy without reducing the productivity of the exposure apparatus. As described above, it is preferable in terms of productivity that the flat plate can be moved separately from the wafer stage. However, in the case of a scanning type exposure apparatus, the uneven illuminance sensor is provided so that the integrated illuminance unevenness during scanning can be measured. It is also advantageous to place it on the wafer stage together.

  By using the function of sucking gas or liquid from the suction port 22, the initial liquid film can be more quickly generated on the final surface 4 s of the projection optical system. A method of generating an initial liquid film using the suction port 22 will be described with reference to FIG.

  First, the flat plate 21 is moved so that the suction port 22 is located just below the center of the liquid supply nozzle 5 disposed so as to surround the outer periphery of the projection lens final surface 4s. In this state, the liquid is supplied onto the flat plate 21 from the entire circumference of the liquid supply nozzle 5 (FIG. 11A).

  The supplied liquid is circumferentially or annularly liquid according to the arrangement of the liquid supply nozzle 5 while leaving the gas g in the center between the plane parallel plate (continuous member) 20 including the projection lens final surface 4s and the plane plate 21. A film f is formed. Even if the liquid is continuously supplied as it is, the gas g is not discharged to the outside because the gas g is contained inside the liquid film f. Therefore, the liquid cannot be completely filled with the liquid no matter what time the space below the projection lens final surface 4s passes.

  Therefore, the gas g is sucked through the suction port 22 in a state where the liquid is supplied from the liquid supply nozzle 5 to the space below the final surface 4s in a circumferential or annular shape. As a result of this suction, the pressure of the gas g becomes negative compared to the pressure in the external environment, and the liquid film formed on the outer periphery acts on the liquid film formed on the outer periphery due to this pressure difference. It begins to spread rapidly toward the mouth 22 (FIG. 11 (b)). Further, when the suction is continued through the suction port 22, the gap between the projection optical system final surface 4 s and the flat plate 21 is filled with a liquid film without gas g when the liquid starts to be sucked through the suction port 22. (FIG. 11 (c)).

  Next, the suction from the suction port 22 is stopped. In the state where the suction is stopped, the supply of the liquid from the liquid supply nozzle 5 may be stopped while the wafer stage 10 is stopped. However, when the liquid is stationary, the gas and impurities constituting the surrounding environment are constantly taken into the liquid. For this reason, the concentration of bubbles and impurities increases, and the generated bubbles remain until they are exposed without exposure, or minute bubbles are generated by exposure, and the final surface of the projection optical system is clouded by the incorporated impurities. Malfunction can occur. In order to avoid this problem, it is preferable that the liquid is continuously supplied while the wafer stage 10 is stopped, and the liquid is recovered at least by the liquid recovery nozzle 6 while the liquid is supplied.

  11 (a) to 11 (c), the liquid recovery nozzle 6 may be stopped, but in order to prevent the liquid from splashing outside due to vibrations or sudden fluctuations in the liquid supply amount, It is preferable that the liquid recovery nozzle 6 is always operated.

  Finally, the wafer stage 21 is moved so that the wafer 9 is positioned immediately below the final surface of the projection optical system while supplying and recovering the liquid (FIG. 11D).

  Thus, if a liquid film formed in a circumferential or annular shape by suction is grown toward the center, it is possible to form a liquid film without bubbles more quickly, and thus the productivity of the exposure apparatus. There is an advantage to improve. Further, according to this method, since the stage does not need to be moved, it is also suitable as a method for generating a liquid film having a particularly large area, such as when a projection optical system having a larger numerical aperture is employed.

  Of course, the liquid film can be quickly recovered by using the suction port 22. That is, from the state where the liquid film is transferred between the final surface 4s of the projection optical system and the flat plate 21, the supply of the liquid from the liquid supply nozzle 5 is stopped, and the liquid is sucked from the suction port 22, whereby the projection optics Most of the liquid film between the system final surface 4s and the liquid suction plate 21 can be quickly recovered. At this time, in order to collect the liquid more completely, the liquid may be sucked while moving the wafer stage 10. By using this liquid film recovery function, the liquid film can be recovered immediately, so that the maintenance / inspection operation of the apparatus and the response operation at the time of failure can be started promptly without delay.

  With reference to FIG. 11, the method for quickly generating the initial liquid film by using the suction port 22 provided in the flat plate 21 has been described. Apart from this method, as shown in FIG. 12, a liquid injection port 23 is provided in the plane plate 21 instead of the suction port 22, and a liquid is supplied from a liquid supply device (not shown) through the liquid injection port 23. The initial liquid film can be rapidly generated as follows. That is, in FIG. 12, first, the flat plate 21 is moved so that the liquid injection port 23 is located almost directly below the center of the liquid supply nozzle 5 arranged so as to surround the outer periphery of the projection lens final surface 4s. From this state, the liquid is supplied onto the flat plate 21 through the liquid inlet 23. The supplied liquid forms a small liquid film between the projection lens final surface 4s and the flat plate 21 including the liquid injection port 23 (FIG. 12A).

  By further supplying the liquid through the liquid injection port 23, the small liquid film f spreads radially (FIG. 12B), and the gap between the final surface 4s of the projection optical system and the flat plate 21 is filled with the liquid. .

  By recovering the liquid through the liquid recovery nozzle 6 as necessary, it is possible to prevent the liquid from protruding from the flat plate 21 or the projection optical system final surface 4s (FIG. 12C).

  Further, by using the liquid injection port 23, as described with reference to FIG. 10, the final surface of the projection optical system without scattering and leaking liquid around the plane plate 21 with the plane plate 21 being stationary. The lower liquid film can be continuously filled with new liquid. Specifically, the liquid is recovered through the liquid recovery nozzle 6 at the same time as the liquid is supplied from the liquid inlet 23. Of course, at this time, the supply of the liquid from the liquid supply nozzle 5 should be interrupted.

  In this way, since the liquid starts to be filled from the substantially center of the space between the flat plate 21 and the projection optical system final surface 4s, the liquid starts to be filled from the outer periphery of the projection optical system final surface 4s using the suction port 22. The contact area with the surrounding gas can be made smaller than the method. Therefore, since the amount of gas dissolved in the initial liquid film and the amount of impurities contained in the gas can be reduced, more stable exposure and resolution performance can be obtained, and the effect of suppressing fogging by impurities can be further enhanced. be able to.

  In addition to the liquid injection port 23, the liquid suction port 22 shown in FIGS. 10 and 11 is provided in the flat plate 21, and the liquid injection port 22 is used for generating an initial liquid film and replacing the liquid film. The liquid suction port 23 may be used for recovering the liquid for replacing the liquid film portion with the surrounding environmental gas. The function of the liquid inlet 22 and the function of the liquid suction port 23 can also be realized by the same opening. That is, both the suction device (not shown) and the liquid supply device (not shown) are connected to the opening provided in the flat plate 21 via a switching valve, and the switching valve is switched to connect the suction port 22 to the opening. The function of the inlet 23 can be switched as necessary. In this way, the flat plate 21 can be made more compact.

  Application of the flat plate 21, the suction port 22, and the injection port 23 described with reference to FIGS. 8 to 12 is used in combination with the liquid supply nozzle and the liquid recovery nozzle explicitly described in this specification. However, the present invention can be used in combination with various liquid supply / recovery mechanisms such as liquid supply and liquid recovery pipes disclosed in WO99 / 49504.

  FIG. 13 is a perspective view showing a sixth configuration example regarding the configuration and arrangement of the liquid supply nozzle and the liquid recovery nozzle. In the configuration example shown in FIG. 13, an outer peripheral surface (protruding surface) 20 c disposed closer to the wafer than the liquid contact surface 20 a is provided on the outer peripheral side of the liquid contact surface 20 a where the liquid supply nozzle 5 is disposed. 6 is different from the configuration example shown in FIG. The liquid recovery nozzle 6 is arranged on the outer peripheral surface 20c in a circumferential shape.

  As described above, by providing the outer peripheral surface 20c closer to the wafer than the liquid contact surface 20a on the outer peripheral side of the liquid contact surface 20a on which the liquid film of the projection optical system final surface 4s is formed, the liquid is in contact with the liquid contact surface. It becomes difficult to escape to the outside of 20a. As a result, it is possible to reduce the ability to recover the liquid through the liquid recovery nozzle 6, and it is possible to reduce the size of the liquid recovery nozzle 6 and the liquid recovery device 8. Here, in the configuration example shown in FIG. 13, the liquid recovery nozzle 6 is provided on the outer surface 20 c side, but the liquid recovery nozzle may be provided, for example, on the 20 a side, or more reliable liquid recovery For this reason, it may be provided on both surfaces 20a and 20c.

  Further, in the configuration example shown in FIG. 13, the outer surface 20c formed with a step with respect to the inner surface 20a is provided so as to surround the projection optical system final surface 4s over the entire circumference. When the movement direction is limited, the outer surface 20c or the stepped portion may be provided only on the downstream side in the wafer movement direction. In this case, the length of the outer side 20c or the stepped portion is preferably the same as or longer than the length of the liquid recovery nozzle.

  The nozzle ports of the liquid supply nozzle 5 and the liquid recovery nozzle 6 may be configured as simple openings. However, in terms of reducing the unevenness in the location of the liquid supply amount and the recovery amount and further preventing the liquid from dripping. It is desirable to provide a porous plate having a plurality of holes or a porous body at the nozzle opening. In particular, a porous body obtained by sintering a fibrous or granular (powdered) metal material or an inorganic material is suitable. Further, as materials (materials constituting at least the surface) used for these, stainless steel, nickel, alumina, and quartz glass are suitable in terms of compatibility with pure water or a fluorinated liquid used as an immersion medium.

  FIG. 14 is a perspective view showing a seventh configuration example regarding the configuration and arrangement of the liquid supply nozzle and the liquid recovery nozzle. The configuration example shown in FIG. 14 is different from the first to sixth configuration examples described above in that an inert gas blowing portion 24 is provided in the outermost peripheral portion surrounding the projection optical system final surface 4s.

  The inert gas blowing portion (blowing ring) 24 communicates with an inert gas supply device (not shown), and blows out the inert gas at a substantially uniform speed toward a wafer or a flat plate arranged below the inert gas supply device. It is configured to be able to. In a state where a liquid film is formed between the final surface 4s of the projection optical system and the wafer or flat plate, an inert gas is blown out from the inert gas blowing section 24, so that the liquid film is exposed from the outer peripheral side. By applying pressure with an inert gas, the liquid constituting the liquid film can be prevented from splashing outside. This advantage functions particularly effectively when the wafer or the flat plate is moving. Further, since the liquid film is pushed toward the center by supplying the inert gas, it is possible to prevent the liquid film from remaining attached to the surface of the wafer or the flat plate. Moreover, the surface of a wafer or a flat plate can be dried by supplying an inert gas. Here, if the inert gas is used only for drying the wafer or the flat plate, the pressure of the inert gas may be low.

  Further, in order to suppress unevenness in the location of the blowing speed in the inert gas blowing section 24, a porous plate or a porous body may be provided at the blowing port as in the liquid supply nozzle 5, and about 0.1 mm. A slit nozzle that blows out inert gas from such a small gap is advantageous in that it further reduces the consumption of inert gas.

  According to the above configuration, it is possible to more reliably prevent the liquid from remaining on the upper surface of the wafer or the flat plate. This eliminates the need for a unit or operation for recovering the remaining liquid at the time of wafer replacement or maintenance, and contributes to improving the productivity of the exposure apparatus and preventing the apparatus from becoming large. In addition, by supplying the inert gas, it is possible to suppress the time for which the surface of the photosensitive agent applied on the upper surface of the wafer is kept wet and to dry the surface of the photosensitive agent immediately. Therefore, the dependency on the wet state, which affects the development process after exposure of the photosensitive agent, can be reduced as much as possible, so that stable resolution performance can be expected from the photosensitive agent.

  In the configuration example shown in FIG. 14, the liquid supply nozzle 5 and the liquid recovery nozzle 6 are provided on the liquid contact surface 20a that is substantially the same as the final surface 4s of the projection optical system, and the flat surface 20c closer to the wafer than the flat surface 20a is provided on the outer peripheral side. And an inert gas blowing portion is provided on the plane 20c. By providing the inert gas blowing portion on the surface closer to the wafer than the liquid contact surface 20a in this way, a large pressure difference can be obtained with a relatively small gas flow rate, and the running cost of the exposure apparatus can be suppressed. The influence of the inert gas on the outside can be minimized. Of course, the effect of the inert gas blowing portion can be sufficiently exhibited even when this is provided in the liquid contact surface 20a. Also in the configuration examples shown in FIGS. 3 to 5, an inert gas blowout section that is the same length as or longer than the liquid supply port 5 and the liquid recovery port 6 and upstream of the wafer moving direction. Can be provided.

  A gas suction portion (suction ring) (not shown) is provided on the outer peripheral side of the inert gas blowing portion 24 shown in FIG. 14, and the inert gas blown out from the inert gas blowing portion 24 is discharged by this gas suction portion. By sucking and collecting the exhaust gas and exhausting the sucked inert gas to a place that does not affect the periphery of the exposure area, the influence of the inert gas on the area around the exposure area can be minimized. Here, as a representative example of the influence of the inert gas on the periphery of the exposure region, for example, the inert gas flows into the optical path of the interferometer that measures the position of the wafer stage or the optical path of the optical focus sensor. The gas component in the optical path becomes non-uniform in time and space, which becomes a fluctuation component of the measurement value and causes a measurement error.

  As the inert gas, it is appropriate to use air or nitrogen from which impurities such as organic matter, acid gas, and alkaline gas have been removed from the fogging of the optical system and impurities and moisture sufficiently affecting the photosensitive agent. In particular, if nitrogen is used, oxygen in the atmosphere can be prevented from dissolving in the liquid filled below the final surface of the projection optical system. Therefore, when using pure water or functional water as the liquid, There is an advantage that the contact surface can be prevented from oxidative corrosion.

  FIG. 15 is a diagram illustrating a preferred configuration example of the liquid supply nozzle 5. The outlet shape of the liquid supply nozzle 5 shown in FIGS. 3 to 8, 13, and 14 is a slit shape. On the other hand, in the configuration example shown in FIG. 15, one nozzle unit (discharge unit) 5 includes n (plural) nozzles J1 to Jn. These nozzles J1 to Jn are connected to the liquid supply device 7 via the open / close valves V1 to Vn, respectively, and by switching the operation of the open / close valves V1 to Vn corresponding to the nozzles J1 to Jn, liquid is supplied. Each can be supplied and stopped individually.

  Further, these nozzle groups may be arranged in a plurality of rows instead of a single row, and according to this, it is possible to increase the supply flow rate, and further to form a liquid film in a complicated shape. Is also possible.

  The nozzle unit 5 composed of a plurality of nozzles, for example, when liquid immersion is performed from the wafer outer peripheral boundary as shown in FIG. Furthermore, it can be controlled to sequentially open the valve corresponding to the nozzle that enters the wafer downward as the wafer moves to supply liquid onto the wafer. Thereby, it is possible to prevent the liquid from protruding to the outside of the wafer. This reduces the equipment load for liquid recovery.

  FIG. 16 shows a case where the wafer moves and enters the region below the nozzle row, but the present invention can also be applied to a case where the wafer moves out of the region below the nozzle row. Further, a coplanar plate may be provided outside the wafer. In this case, the supply of liquid from each nozzle may be controlled corresponding to the outer edge of the coplanar plate, thereby minimizing the size of the coplanar plate. be able to. Therefore, the moving distance of the wafer stage can be reduced, and the apparatus size can be reduced.

  Further, in the configuration example shown in FIG. 15, supply / stop of the liquid from each nozzle of the nozzle unit 5 is performed by opening / closing a corresponding opening / closing valve. Alternatively, for example, as used in an ink jet printer, it is possible to embed a function of discharging and stopping droplets in each nozzle of the nozzle unit. It is also possible to form a substantially continuous liquid film on the wafer by ejecting the droplets at high frequency. Specifically, structures and functions such as a bubble jet (registered trademark) nozzle, a thermal jet nozzle, or a piezo jet nozzle can be applied.

  According to a preferred embodiment of the present invention, in a projection exposure apparatus to which a liquid immersion method is applied, a liquid film is formed between the final surface of the projection optical system and the substrate in a short time without causing droplets to scatter around. In addition, it is possible to suppress the generation of minute bubbles that become a problem during projection exposure. Moreover, the operation | work which collect | recovers liquid separately for every board | substrate, every alignment process implemented prior to exposure, or every various processes for maintaining the performance of exposure apparatus becomes unnecessary. In addition, the final surface of the projection optical system can always be covered with a high-purity liquid, and the contact area with the environmental atmosphere can be reduced, so that predetermined exposure and resolution performance can be stably obtained. Furthermore, fogging due to impurities contained in the environment or in the photosensitive agent can be suppressed or prevented. As a result, highly accurate and stable projection exposure can be performed without increasing the scale of the exposure apparatus and without impairing the productivity of the exposure apparatus, and a fine pattern can be stably and satisfactorily transferred onto the substrate. be able to.

  Next, a process for manufacturing a semiconductor device as an example of a device such as a micro device using the above-described exposure apparatus will be described. FIG. 17 is a diagram showing a flow of an entire manufacturing process of a semiconductor device. In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (mask fabrication), a mask is fabricated based on the designed circuit pattern.

  On the other hand, in step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by using the above-described exposure apparatus and lithography technology using the above-described mask and wafer. The next step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer produced in step 5, and is an assembly process (dicing, bonding), packaging process (chip encapsulation), etc. Process. In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. A semiconductor device is completed through these processes, and is shipped in Step 7.

  The wafer process in step 4 includes the following steps. An oxidation step for oxidizing the surface of the wafer, a CVD step for forming an insulating film on the wafer surface, an electrode formation step for forming electrodes on the wafer by vapor deposition, an ion implantation step for implanting ions on the wafer, and applying a photosensitive agent to the wafer A resist processing step, an exposure step for transferring the circuit pattern to the wafer after the resist processing step by the above exposure apparatus, a development step for developing the wafer exposed in the exposure step, and an etching step for scraping off portions other than the resist image developed in the development step A resist stripping step that removes the resist that has become unnecessary after etching. By repeating these steps, multiple circuit patterns are formed on the wafer.

  According to the present invention, it is possible to improve the practicality of an exposure apparatus and an exposure method to which the immersion method is applied, for example, more reliably fill a gap between the final surface of the projection optical system and the substrate with the liquid, or projection optics. The possibility that the final surface of the system is exposed to the atmosphere surrounding it can be reduced, or the structure of the exposure apparatus can be simplified and the exposure apparatus can be downsized.

It is a figure which shows schematically the structure of suitable embodiment of this invention. It is a figure which shows typically the process of filling the space | interval of a projection optical system and a wafer with a liquid in suitable embodiment of this invention. It is a figure which shows the 1st structural example of the liquid supply nozzle and liquid recovery nozzle in the exposure apparatus of suitable embodiment of this invention. It is a figure which shows the 2nd structural example of the liquid supply nozzle and liquid recovery nozzle in the exposure apparatus of suitable embodiment of this invention. It is a figure which shows the 3rd structural example of the liquid supply nozzle and liquid recovery nozzle in the exposure apparatus of suitable embodiment of this invention. It is a figure which shows the 4th structural example of the liquid supply nozzle and liquid recovery nozzle in the exposure apparatus of suitable embodiment of this invention. It is a figure which shows the 5th structural example of the liquid supply nozzle and liquid recovery nozzle in the exposure apparatus of suitable embodiment of this invention. It is a figure which shows roughly the partial structure of other suitable embodiment of this invention. It is a figure which shows the process of sending a plane plate under a projection optical system in the exposure apparatus of other suitable embodiment of this invention. It is a figure which shows the other process of sending a plane plate under a projection optical system in the exposure apparatus of other suitable embodiment of this invention. It is a figure which shows the process of producing | generating a liquid film under a projection optical system in the exposure apparatus of suitable embodiment of this invention. It is the figure which showed the other process of producing | generating a liquid film under a projection optical system in the exposure apparatus of suitable embodiment of this invention. It is a figure which shows the 6th structural example of the liquid supply nozzle and liquid recovery nozzle in the exposure apparatus of suitable embodiment of this invention. It is a figure which shows the 7th structural example of the liquid supply nozzle and liquid recovery nozzle in the exposure apparatus of suitable embodiment of this invention. It is a figure which shows the structural example of the nozzle unit (nozzle unit comprised by multiple nozzles) in the exposure apparatus of suitable embodiment of this invention. It is a figure which shows the example of application of the nozzle unit shown in FIG. It is a figure which shows the flow of the whole manufacturing process of a semiconductor device.

Explanation of symbols

1: Reticle 2: Illumination system 3: Reticle stage 4: Projection optical system 4s: Projection optical system final surfaces 5, 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h: Liquid supply nozzles 6, 6a, 6b, 6c, 6d, 6e, 6f, 6g, 6h: liquid recovery nozzle 7: liquid supply device 8: liquid recovery device 9: wafer 10: wafer stage 11: reference mirror 12: distance measuring laser interferometer 13: stage control device,
14, 15: Surface plate 16: Supply pipe 17: Recovery pipe 18: Immersion control device 19: Same surface plates 20, 20a, 20b: Continuous member (liquid contact surface)
20c: outer peripheral surface 21: flat plate 22: suction port 23: liquid injection port 24: inert gas blowing part f: liquid for immersion g: gas ea: exposure slit regions J1, J2... Jn: nozzles V1, V2 ... Vn: Open / close valve

Claims (9)

Includes a projection optical system for projecting a pattern of an original onto a substrate, with the gap filled with liquid between a final surface and the substrate of the projection optical system, an exposure apparatus for exposing a substrate,
A substrate stage movable with respect to the projection optical system and holding the substrate;
A plane plate movable relative to the projection optical system and having an upper surface substantially the same height as the upper surface of the substrate held by the substrate stage ;
Supply means for supplying the liquid to the gap ;
Recovery means for recovering the liquid from the gap ;
An exposure apparatus comprising: a sensor provided on the flat plate and receiving exposure light through the liquid . An exposure apparatus that has a projection optical system that projects an original pattern onto a substrate, and that exposes the substrate in a state where a liquid is filled in a gap between the final surface of the projection optical system and the substrate,
  A substrate stage movable with respect to the projection optical system and holding the substrate;
  A planar plate disposed on the substrate stage and having an upper surface substantially the same height as the upper surface of the substrate held on the substrate stage;
  Supply means for supplying the liquid to the gap;
  Recovery means for recovering the liquid from the gap;
  An exposure apparatus comprising: a sensor disposed on the substrate stage and receiving exposure light through the liquid. An exposure apparatus that has a projection optical system that projects an original pattern onto a substrate, and that exposes the substrate in a state where a liquid is filled in a gap between the final surface of the projection optical system and the substrate,
  A substrate stage movable with respect to the projection optical system and holding the substrate;
  An exposure apparatus comprising: a sensor that is movable with respect to the projection optical system independently of the substrate stage, and that receives exposure light through the liquid.   The sensor includes any one of an illuminance unevenness sensor for measuring an illuminance distribution of the exposure light and an absolute illuminometer for measuring the absolute illuminance of the exposure light. 4. The exposure apparatus according to any one of items 3.   The exposure apparatus according to claim 1, wherein the arrangement in which the flat plate is opposed to the final surface is performed in parallel with supply or collection of the substrate with respect to the substrate stage.   2. The exposure apparatus according to claim 1, wherein the arrangement of the flat plate facing the final surface is performed in parallel with the alignment measurement of the substrate held on the substrate stage.   2. The exposure apparatus according to claim 1, wherein the arrangement in which the flat plate faces the final surface is performed in parallel with the operation for maintaining or managing the exposure apparatus. A master stage that is movable with respect to the projection optical system and holds the master;
The exposure according to any one of claims 1 to 7, wherein the substrate is exposed through a pattern of the original while the original and the substrate are scanned and moved with respect to the projection optical system. apparatus. Exposing the substrate using the exposure apparatus according to any one of claims 1 to 8,
And developing the substrate exposed in the step.

Images