WO1999049504A1 - Projection exposure method and system - Google Patents

Abstract

A projection exposure method capable of keeping a liquid (7) filled between a projection optical system (PL) and a wafer (W) even while the wafer (W) is being moved when a liquid immersion method is used to conduct an exposure, wherein a discharge nozzle (21a) and inflow nozzles (23a, 23b) are disposed so as to hold a lens (4) at the tip end of the projection optical system (PL) in an X direction. When the wafer (W) is moved in a -X direction by an XY stage (10), a liquid (7) controlled to a preset temperature is supplied from a liquid supply device (5) via a supply pipe (21) and the discharge nozzle (21a) so as to fill the portion between the lens (4) and the surface of the wafer (W) and the liquid (7) is recovered from the surface of the wafer (W) by a liquid supply device (6) via a recovery pipe (23) and the inflow nozzles (23a, 23b), the supply amount and recovery amount of the liquid (7) being regulated according to a moving speed of the wafer (W).

Description

 W 99/49504 P T / JP

Projection exposure method and apparatus

 According to the present invention, for example, a mask pattern is formed on a photosensitive substrate in a lithographic process for manufacturing a device such as a semiconductor device, an imaging device (such as a CCD), a liquid crystal display device, or a thin-film magnetic head. The present invention relates to a projection exposure method and apparatus used for transfer, and more particularly to a projection exposure method and apparatus using an immersion method. Background art

 When manufacturing semiconductor devices, etc., an image of a reticle pattern as a mask is projected onto each shot area on a wafer (or a glass plate, etc.) coated with a resist as a photosensitive substrate via a projection optical system. A transfer projection exposure device is used. Conventionally, a step-and-repeat type reduction projection type exposure apparatus (stepper) has been frequently used as a projection exposure apparatus. Recently, however, a step-and-scan method in which exposure is performed by synchronously scanning a reticle and a wafer. Attention has been paid to a projection exposure apparatus of the type.

The resolution of the projection optical system provided in the projection exposure apparatus increases as the exposure wavelength used decreases and as the numerical aperture of the projection optical system increases. For this reason, with the miniaturization of integrated circuits, the exposure wavelength used in projection exposure apparatuses is becoming shorter year by year, and the numerical aperture of projection optical systems is also increasing. The exposure wavelength currently mainstream is 248 nm for KrF excimer lasers, but 193 nm for shorter-wavelength ArF excimer lasers is being put into practical use. When performing exposure, the depth of focus (DOF) is as important as the resolution. Resolution R and depth of focus (5 are each represented by the following equations.

 R = k, 'λ ΝΑ (1)

δ = k 2λ ΖΝΑ ² (2)

Here, lambda is the exposure wavelength, Nyuarufa is the numerical aperture of the projection optical system, k,, k ₂ is a process factor. From Equations (1) and (2), it can be seen that when the exposure wavelength λ is shortened and the numerical aperture 大 き く is increased to increase the resolution R, the depth of focus <5 is reduced. Conventionally, in a projection exposure apparatus, exposure is performed by aligning the surface of a wafer with an image plane of a projection optical system by an autofocus method. To this end, it is desirable that the depth of focus δ is wide to some extent. Therefore, proposals have been made to substantially increase the depth of focus, such as the phase shift reticle method, the modified illumination method, and the multilayer resist method.

 As described above, in the conventional projection exposure apparatus, the depth of focus is becoming narrower due to the shorter wavelength of the exposure light and the increase in the numerical aperture of the projection optical system. In order to cope with higher integration of semiconductor integrated circuits, research on even shorter exposure wavelengths has been studied. In this case, the depth of focus becomes too narrow, and the margin during the exposure operation may be insufficient. There is.

 Therefore, an immersion method has been proposed as a method of substantially shortening the exposure wavelength and increasing the depth of focus. This is because the space between the lower surface of the projection optical system and the wafer surface is filled with water or a liquid such as an organic solvent, and the wavelength of the exposure light in the liquid is lZn times that in air (η is the refractive index of the liquid. (Approximately 1.2 to 1.6) to improve the resolution and increase the depth of focus to about η times.

Assuming that this immersion method is simply applied to a step-and-repeat projection exposure apparatus, after exposing one shot area, when step-moving the wafer to the next shot area, Projection optics and wafer In this case, the liquid must be supplied again because the liquid comes out from the space between the two, and there is a disadvantage that it is difficult to recover the liquid. Also, if the immersion method is applied to a step-and-scan projection exposure apparatus, the exposure is performed while moving the wafer, so that the projection optical system and the wafer are not moved while the wafer is being moved. It is necessary that the liquid is filled between them.

 In view of the above, the present invention provides a liquid between the projection optical system and the wafer stably even if the projection optical system and the wafer are relatively moved when the immersion method is applied. It is an object of the present invention to provide a projection exposure method that can be set. Further, the present invention provides a projection exposure apparatus capable of performing such a projection exposure method, an efficient manufacturing method of the projection exposure apparatus, and a method of manufacturing a high-performance device using such a projection exposure method. The purpose is also. Disclosure of the invention

 In the first projection exposure method according to the present invention, a mask (R) is illuminated with an exposure beam, and a pattern of the mask (R) is transferred onto a substrate (W) via a projection optical system (PL). In the method, when the substrate (W) is moved in a predetermined direction, the tip of the optical element (4) on the substrate (W) side of the projection optical system (PL) and the surface of the substrate (W) The predetermined liquid (7) is caused to flow along the direction of movement of the substrate (W) so as to satisfy the condition (1).

According to the first projection exposure method of the present invention, the liquid immersion method is applied to fill the space between the tip of the projection optical system (PL) and the substrate (W) with the liquid. The wavelength of the exposure light on the surface can be shortened to 1Zn times the wavelength in air (where n is the refractive index of the liquid), and the depth of focus is expanded about n times compared to in air. Also, when the substrate is moved along a predetermined direction, the liquid flows along the moving direction of the substrate. In addition, the space between the tip of the projection optical system and the surface of the substrate is filled with the liquid. In addition, when foreign matter is attached to the substrate, the foreign matter attached to the substrate can be washed away with the liquid.

 Next, the first projection exposure apparatus according to the present invention illuminates the mask (R) with the exposure beam, and transfers the pattern of the mask (R) onto the substrate (W) via the projection optical system (PL). In a projection exposure apparatus, a substrate stage (9, 10) for holding and moving the substrate (W), and a tip of an optical element (4) on the substrate (W) side of the projection optical system (PL). A liquid supply device (5) for supplying a predetermined liquid (7) along a predetermined direction through a supply pipe (21a) so as to fill the space between the substrate and the surface of the substrate (W); From the surface of the substrate (W) through the discharge pipes (23a, 23b) arranged so as to sandwich the irradiation area of the exposure beam in the predetermined direction together with the supply pipes (21a). And a liquid recovery device (6) for recovering the liquid (7). The substrate stage (9, 10) is driven to remove the substrate (W). When moving along the Jo Tokoro, and performs supply and recovery of the liquid (7).

 According to the first projection exposure apparatus of the present invention, the first projection exposure method of the present invention can be performed by using those pipes. In addition, the pair of supply pipes (21a) and the discharge pipes (23a, 23b) are rotated substantially 180 ° so that a second pair of supply pipes (22 It is desirable to provide a) and pipes for discharge (24a, 24b). In this case, when the substrate (W) is moved in a direction opposite to the predetermined direction, the tip of the projection optical system (PL) and the substrate (W) are used by using the latter pair of pipes. The liquid (7) can be more stably filled with the liquid surface.

The projection exposure apparatus converts the mask (R) and the substrate (W) into the projection light. In the case of a scanning exposure type in which exposure is performed synchronously with respect to the science (PL), it is desirable that the predetermined direction is the scanning direction of the substrate (W) at the time of scanning exposure. In this case, even during the scanning exposure, the liquid (7) flows between the tip of the optical element (4) on the substrate (W) side of the projection optical system (PL) and the surface of the substrate (W). ), The exposure can be performed with high accuracy and stability.

 Also, in a direction orthogonal to the predetermined direction, one pair or two pairs in an arrangement corresponding to the pair of supply pipes (21a) and the discharge pipes (23a, 23b). It is desirable to provide a supply pipe (27a) and a discharge pipe (29a, 29b). In this case, even when the substrate (W) is step-moved in a direction orthogonal to the predetermined direction, the liquid is moved between the front end of the projection optical system (PL) and the surface of the substrate (W). (7) can be satisfied.

 It is desirable to have a control system (14) for adjusting the supply amount and the recovery amount of the liquid (7) according to the moving speed of the substrate stage. That is, for example, when the moving speed is high, the supply amount is increased, and when the moving speed is low, the supply amount is reduced, so that the tip of the projection optical system (PL) and the The space between the substrate and the surface of the substrate (W) can be kept constant.

The liquid (7) supplied to the surface of the substrate (W) is, for example, pure water or a fluorine-based inert liquid adjusted to a predetermined temperature. In this case, pure water is easily available at, for example, a semiconductor manufacturing plant, and there is no environmental problem. Further, since the temperature of the liquid (7) is adjusted, the temperature of the substrate surface can be adjusted, and thermal expansion of the substrate (W) due to heat generated during exposure can be prevented. Naturally, it is desirable that the liquid has a high transmittance to the exposure beam. P

6 Since the working distance of the shadow optics is short, the absorption of the exposure beam is extremely small. Next, the method for manufacturing a projection exposure apparatus according to the present invention comprises an illumination system (1) for irradiating an exposure beam onto a mask (R), and a projection optical system (1) for transferring an image of a pattern of the mask onto a substrate (W). PL), the substrate stage (9, 10) for holding and moving the substrate (W), and the tip of the optical element (4) on the substrate (W) side of the projection optical system (PL). A liquid supply device (5) for supplying a predetermined liquid (7) along a predetermined direction via a supply pipe (21a) so as to fill the space between the substrate and the surface of the substrate (W); The substrate (W) is connected to the supply pipe (21a) via the discharge pipe (23a, 23b) arranged so as to sandwich the exposure beam irradiation area (4) in the predetermined direction together with the supply pipe (21a). A projection exposure apparatus is manufactured by assembling a liquid recovery device (6) for recovering the liquid (7) from the surface of the device with a predetermined positional relationship.

 A first device manufacturing method according to the present invention is a device manufacturing method using the first projection exposure method according to the present invention, wherein a mask (R) is illuminated with an exposure beam, and the mask (R) is illuminated. ) Is transferred to the device substrate (W) via the projection optical system (PL) through the projection optical system (PL). In this exposure step, when the substrate (W) is moved along a predetermined direction, In order to fill the gap between the tip of the optical element (4) on the substrate (W) side of the projection optical system (PL) and the surface of the substrate (W), along the moving direction of the substrate (W) A predetermined liquid (7) is allowed to flow, and a high-performance device can be manufactured by applying the immersion method.

Next, a second projection exposure method according to the present invention is directed to a projection exposure method for illuminating a mask (R) with an exposure beam and exposing a substrate (W) with the exposure beam via a projection optical system (PL). The liquid (7) flows so as to fill the space between the projection optical system and the substrate, and the direction in which the liquid flows varies according to the moving direction of the substrate. According to the second projection exposure method of the present invention, since the liquid between the projection optical system (PL) and the substrate (W) is filled with the liquid by applying the immersion method, the exposure light on the substrate surface is exposed. Can be shortened to 1Zn times the wavelength in air (n is the refractive index of the liquid), and the depth of focus is about n times wider than in air. In addition, by changing the direction in which the liquid flows in accordance with the direction of movement of the substrate, even if the direction of movement of the substrate changes frequently, the distance between the projection optical system and the substrate is reduced. Can be filled with liquid.

 Further, when the supply speed of the liquid (7) is divided into a first component in the moving direction of the substrate and a second component orthogonal to the moving direction, the first component is in the moving direction of the substrate (W). When the direction is opposite to the above, it is desirable to flow the liquid (7) so as to be smaller than a predetermined allowable value. This reduces the velocity component of the liquid in the direction opposite to the direction of movement of the substrate (W), so that the liquid can be supplied smoothly.

 More preferably, the liquid (7) flows in the same direction substantially along the direction of movement of the substrate (W).

 When the substrate (W) is exposed by the step-and-repeat method or the step-and-scan method, the liquid (7) is caused to flow substantially along the stepping direction of the substrate (W). It is desirable.

 Further, the mask (R) and the substrate (W) are relatively moved with respect to the exposure beam, and the substrate is scanned and exposed with the exposure beam, and the substrate is scanned in the scanning direction during the scanning exposure. It is desirable to flow the liquid (7) approximately along.

 It is desirable to adjust the flow rate of the liquid (7) according to the moving speed of the substrate ν).

Next, the method for manufacturing a second device according to the present invention includes the second method according to the present invention. The method includes a lithographic process including a step of transferring a device pattern onto a substrate (W) using a shadow exposure method. A high-performance device can be manufactured by applying an immersion method.

 Next, a second projection exposure apparatus according to the present invention illuminates a mask (R) with an exposure beam and exposes the substrate (W) with the exposure beam via a projection optical system (PL). A liquid supply device (5) for flowing the liquid (7) so as to fill the space between the projection optical system and the substrate, and changing the flowing direction of the liquid according to the moving direction of the substrate. is there.

 According to such a second projection exposure apparatus of the present invention, the second projection exposure method of the present invention can be implemented, and even when the moving direction of the substrate changes frequently, The liquid can be filled between the projection optical system and the substrate.

 In addition, a stage ′ system (RST, 9 to 11) for moving the mask (R) and the substrate (W) relative to the exposure beam is further provided, and the liquid supply device (5) During the scanning exposure of the substrate, it is desirable to flow the liquid (7) substantially along the moving direction of the substrate.

 Further, it is desirable to further include a liquid recovery device (6) for recovering the liquid (7) supplied between the projection optical system (PL) and the substrate (W). It is desirable that the supply port (21a) of (5) and the recovery port (23a, 23b) of the liquid recovery device (6) are arranged with the irradiation area of the exposure beam interposed therebetween. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a schematic configuration of a projection exposure apparatus used in the first embodiment of the present invention. Fig. 2 shows the lens 4 of the projection optical system PL in Fig. 1. FIG. 6 is a diagram showing a positional relationship between a tip 4A of the X-axis and a discharge nozzle and an inflow nozzle for the X direction. FIG. 3 is a diagram showing the positional relationship between the tip 4A of the lens 4 of the projection optical system PL in FIG. 1, and the discharge nozzle and the inflow nozzle that supply and recover the liquid from the Y direction. FIG. 4 is an enlarged view of a main part showing how the liquid 7 is supplied and recovered between the lens 4 and the wafer W in FIG. FIG. 5 is a front view showing the lower end of the projection optical system PLA of the projection exposure apparatus used in the second embodiment of the present invention, the liquid supply device 5, the liquid recovery device 6, and the like. FIG. 6 is a diagram showing a positional relationship between the tip 32A of the lens 32 of the projection optical system PLA of FIG. 5 and the discharge nozzle and the inflow nozzle for the X direction. FIG. 7 is a diagram showing the positional relationship between the tip 32A of the lens 32 of the projection optical system PLA in FIG. 5, and the discharge nozzle and the inflow nozzle that supply and recover the liquid from the Y direction. BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, an example of a preferred embodiment of the present invention will be described with reference to FIGS. In this embodiment, the present invention is applied to a case where exposure is performed by a step-and-repeat projection exposure apparatus.

FIG. 1 shows a schematic configuration of the projection exposure apparatus of the present embodiment. In FIG. Exposure light IL composed of ultraviolet pulse light of wavelength 248 nm emitted from optical system 1 illuminates the pattern provided on reticle R. The pattern of the reticle R is photolithographic at both sides (or one side on the wafer W side) through a telecentric projection optical system PL at a predetermined projection magnification] 3 (3 is, for example, 1/4, 1Z5, etc.). Is reduced and projected on the exposure area on the wafer W to which the is applied. The exposure light IL includes ArF excimer laser light (wavelength 1933 nm), F 2 Laser light (wavelength: 157 nm) or i-line from a mercury lamp (wavelength: 365 nm) may be used. Hereinafter, the Z axis is taken parallel to the optical axis AX of the projection optical system PL, the Y axis is taken perpendicular to the plane of FIG. 1 in a plane perpendicular to the Z axis, and the X axis is taken parallel to the plane of FIG. Will be explained.

 The reticle R is held on a reticle stage R ST, and the reticle stage R ST incorporates a mechanism for finely moving the reticle R in the X, Y, and rotation directions. The two-dimensional position and rotation angle of reticle stage RST are measured in real time by a laser interferometer (not shown), and main control system 14 positions reticle R based on the measured values.

 On the other hand, the wafer W is fixed via a wafer holder (not shown) on a Z stage 9 for controlling a focus position (a position in the Z direction) and an inclination angle of the wafer W. 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 XY stage 10 is mounted on a base 11. The Z stage 9 controls the focus position (position in the Z direction) and the tilt angle of the wafer W to adjust the surface on the wafer W to the image plane of the projection optical system PL by an autofocus method and an autoleveling method. The XY stage 10 positions the wafer W in the X and Y directions. The two-dimensional position and rotation angle of the Z stage 9 (wafer W) are measured in real time by the laser interferometer 13 as the position of the movable mirror 12. Control information is sent from the main control system 14 to the wafer stage drive system 15 based on the measurement result, and the wafer stage drive system 15 controls the operation of the Z stage 9 and the XY stage 10 based on the control information. . During exposure, each shot area on the wafer W is sequentially moved to the exposure position, and the operation of exposing the pattern image of the reticle R is repeated in a step-and-repeat manner.

In this example, the exposure wavelength is substantially shortened to improve the resolution and Apply the immersion method to increase the depth of focus substantially. For this reason, at least while the transfer image of the reticle R is being transferred onto the wafer W, the surface of the wafer W and the tip surface (lower surface) of the lens 4 on the wafer side of the projection optical system PL And a predetermined liquid 7 is filled. The projection optical system PL has a lens barrel 3 that houses another optical system and a lens 4 thereof, and is configured so that the liquid 7 contacts only the lens 4. Thus, corrosion of the lens barrel 3 made of metal is prevented.

The projection optical system PL is composed of a plurality of optical elements including a lens 4, and the lens 4 is fixed to the lowermost part of the lens barrel 3 so as to be detachable (exchangeable). In this example, the lens is the optical element closest to the wafer W, that is, the optical element that comes into contact with the liquid 7, but the optical element is not limited to the lens, and the optical characteristics of the projection optical system PL, such as aberration (spherical) An optical plate (parallel plane plate or the like) used for adjusting aberration, coma aberration, or the like may be used. In addition, since the surface of the optical element that comes into contact with the liquid 7 due to scattered particles generated from the registry due to exposure of the exposure light or the attachment of impurities in the liquid 7 becomes dirty, the optical element is periodically replaced. There is a need. However, if the optical element that comes into contact with the liquid 7 is a lens, the cost of replacement parts is high and the time required for replacement is long, leading to an increase in maintenance cost (running cost) and a decrease in throughput. . Therefore, the optical element that comes into contact with the liquid 7 may be, for example, a parallel flat plate that is less expensive than the lens 4. In this case, the transmittance of the projection optical system PL during transportation, assembly, adjustment, and the like of the projection exposure apparatus Even if a substance (for example, a silicon-based organic substance) that reduces the illuminance of the exposure light and the uniformity of the illuminance distribution on the wafer W adheres to the parallel flat plate, the parallel flat plate may be provided immediately before the liquid 7 is supplied. It is only necessary to replace the face plate, and there is an advantage that the replacement cost is lower than when the optical element that comes into contact with the liquid 7 is a lens. In this example, pure water is used as the liquid 7, for example. Pure water has the advantage that it can be easily obtained in large quantities at semiconductor manufacturing plants and the like, and that there is no adverse effect on the photoresist on the wafer, optical lenses, and the like. In addition, pure water has no adverse effect on the environment and has an extremely low impurity content, so that it can be expected to have an effect of cleaning the surface of the wafer and the surface of the lens 4.

 Since the refractive index n of pure water (water) with respect to exposure light having a wavelength of about 250 nm is approximately 1.4, the wavelength of KrF excimer laser light, 248 nm, The wavelength is shortened to lZn, that is, about 1777 nm, and a high resolution is obtained. Furthermore, since the depth of focus is expanded about n times, that is, about 1.4 times as compared with that in the air, when it is sufficient to secure the same depth of focus as that used in the air, the projection optical system The numerical aperture of the PL can be further increased, and the resolution is improved in this respect as well.

The liquid 7 is supplied to the wafer W through a predetermined discharge nozzle or the like in a temperature-controlled manner by a liquid supply device 5 including a liquid tank, a pressure pump, a temperature control device, and the like. The liquid is collected from the wafer W through a predetermined inflow nozzle or the like by a liquid recovery device 6 including a tank and a suction pump. The temperature of the liquid 7 is set to, for example, about the same as the temperature in the chamber in which the projection exposure apparatus of the present example is stored. Then, a discharge nozzle 21a having a narrow tip so as to sandwich the distal end of the lens 4 of the projection optical system PL in the X direction, and two inflow nozzles 23a and 23b having a wide distal end (See Fig. 2), the discharge nozzle 2 la is connected to the liquid supply device 5 through the supply pipe 21, and the inflow nozzles 23 a and 23 b are recovered through the recovery pipe 23 Connected to device 6. Further, the pair of discharge nozzles 21a and the pair of nozzles arranged such that the inflow nozzles 23a and 23b are rotated by approximately 180 °, and the tip of the lens 4 are sandwiched in the Y direction. There are also arranged two pairs of discharge nozzles, and an inflow nozzle, FIG. 2 shows the positional relationship between the tip 4A and the wafer W of the lens 4 of the projection optical system PL of FIG. 1 and two pairs of discharge nozzles and inflow nozzles that sandwich the tip 4A in the X direction. In FIG. 2, the discharge nozzle 21a is arranged on the + X direction side of the tip 4A, and the inflow nozzles 23a and 23b are arranged on the one X direction side. The inflow nozzles 23a and 23b are arranged so as to open in a fan shape with respect to an axis passing through the center of the tip 4A and parallel to the X axis. Then, one pair of discharge nozzles 21a and inflow nozzles 23a and 23b are rotated by approximately 180 °, and another pair of discharge nozzles 22a and inflow nozzles 24a and 24a are arranged. 4 b is arranged, the discharge nozzle 22 a is connected to the liquid supply device 5 via the supply pipe 22, and the inflow nozzles 24 a, 24 b are connected to the liquid recovery device 6 via the recovery pipe 24. It is connected.

FIG. 3 shows the positional relationship between the tip 4A of the lens 4 of the projection optical system PL of FIG. 1 and two pairs of discharge nozzles and inflow nozzles that sandwich the tip 4A in the Y direction. In FIG. 3, discharge nozzles 2 Ί Ά, 流入 inflow direction nozzles 29 a, 29 b are disposed on the + Y direction side of the tip 4 A, and discharge nozzle 27 a is connected to the supply pipe 27. The inlet nozzles 29 a and 29 b are connected to the liquid recovery device 6 via the recovery pipe 29. In addition, another pair of discharge nozzles 28a and inflow nozzles 30a, 3a are arranged by rotating one pair of discharge nozzles 27a and inflow nozzles 29a, 29b by approximately 180 °. 0b is arranged, the discharge nozzle 28a is connected to the liquid supply device 5 through the supply pipe 28, and the inflow nozzles 30a and 30b are connected to the liquid recovery device 6 through the recovery pipe 30. Have been. The liquid supply device 5 supplies a temperature-controlled liquid between the front end 4 A of the lens 4 and the wafer W through at least one of the supply pipes 21, 22, 27, 28. The liquid recovery device 6 recovers the liquid via at least one of the recovery tubes 23, 24, 29, and 30. Next, a method for supplying and recovering the liquid 7 will be described.

 In FIG. 2, when the wafer W is step-moved in the direction of the arrow 25 A (in the X direction) indicated by a solid line, the liquid supply device 5 is connected via the supply pipe 21 and the discharge nozzle 21 a. The liquid 7 is supplied between the tip 4 A of the lens 4 and the wafer W. Then, the liquid recovery device 6 recovers the liquid 7 from above the wafer W via the recovery pipe 23 and the inflow nozzles 23a and 23b. At this time, the liquid 7 flows on the wafer W in the direction of the arrow 25B (the direction X), and the space between the wafer W and the lens 4 is stably filled with the liquid 7.

 On the other hand, when stepping the wafer W in the direction of the arrow 26 A (+ X direction) indicated by the two-dot chain line, the liquid supply device 5 uses the supply pipe 22 and the discharge nozzle 22 a. The liquid 7 is supplied between the tip 4A of the lens 4 and the wafer W, and the liquid recovery device 6 recovers the liquid 7 using the recovery pipe 24 and the inflow nozzles 24a and 24b. At this time, the liquid 7 flows on the wafer W in the direction of arrow 26 B (+ X direction), and the space between the wafer W and the lens 4 is filled with the liquid 7. As described above, in the projection exposure apparatus of the present example, since the two pairs of discharge nozzles and inflow nozzles that are mutually inverted in the X direction are provided, the wafer W is moved in either the + X direction or the −X direction. In this case, the space between the wafer W and the lens 4 can be stably filled with the liquid 7.

Further, since the liquid 7 flows on the wafer W, even if foreign matter (including scattered particles from the resist) adheres to the wafer W, the foreign matter can be washed away by the liquid 7. There are advantages. In addition, since the liquid 7 is adjusted to a predetermined temperature by the liquid supply device 5, the temperature of the surface of the wafer W is adjusted, and the overlay accuracy and the like due to the thermal expansion of the wafer due to heat generated during exposure are adjusted. Drop can be prevented. Therefore, even if there is a time lag between the alignment and the exposure as in the EGA (Enhanced's Global Alignment) method, the thermal expansion of the wafer This can prevent the overlay accuracy from being reduced. Further, in the projection exposure apparatus of this example, since the liquid 7 flows in the same direction as the direction in which the wafer W is moved, the foreign matter or the liquid that has absorbed heat is deposited on the exposure area immediately below the tip 4 A of the lens 4. It can be collected without stagnation.

 When the wafer W is moved stepwise in the Y direction, the liquid 7 is supplied and recovered from the Y direction.

 That is, when the wafer is step-moved in the direction of the arrow 31 A (-Y direction) indicated by the solid line in FIG. 3, the liquid supply device 5 is connected via the supply pipe 27 and the discharge nozzle 27a. The liquid is supplied, and the liquid recovery unit 6 recovers the liquid using the recovery pipe 29 and the inlet nozzles 29a and 29b, and the liquid is collected on the exposure area immediately below the tip 4A of the lens 4. Flows in the direction of arrow 31B (-Y direction). When the wafer is stepped in the + Y direction, liquid supply and recovery are performed using the supply pipe 28, the discharge nozzle 28a, the recovery pipe 30, and the inflow nozzles 30a, 30b. The liquid flows in the + Y direction on the exposure area just below the tip 4A. As a result, similarly to the case where the wafer W is moved in the X direction, whether the wafer W is moved in the + Y direction or the one Y direction, the position of the wafer W and the tip 4A of the lens 4 is The space can be filled with liquid 7.

 In addition, not only a nozzle for supplying and recovering the liquid 7 from the X direction or the Y direction, but also a nozzle for supplying and recovering the liquid 7 from an oblique direction may be provided.

Next, a method of controlling the supply amount and the recovery amount of the liquid 7 will be described. FIG. 4 shows how the liquid 7 is supplied and recovered between the lens 4 of the projection optical system PL and the wafer W. In FIG. 4, the wafer W is positioned in the direction of the arrow 25 A (−X direction). The liquid 7 supplied from the discharge nozzle 21a flows in the direction of the arrow 25B (-X direction), and flows into the inlet nozzles 23a and 2b. Recovered by 3b. In this example, the supply amount V i (m ³ / s) of the liquid 7 and the collection amount V o ( m ³ / s) and supply amount of liquid 7 in proportion to the moving speed V of XY stage 10 (wafer W).

Adjust V i and recovery volume V o. That is, the main control system 14 determines the supply amount Vi and the recovery amount Vo of the liquid 7 by the following equations.

 V i = V o = D-v-d (3)

 Here, as shown in Fig. 1, D is the diameter of the tip of the lens 4 (m), V is the moving speed of the XY stage 10 (mZs), and d is the working distance of the projection optical system PL (working distance). (M). The speed V during the step movement of the XY stage 10 is set by the main control system 14. Since D and d are input in advance, the supply of the liquid 7 is performed based on the equation (3). By adjusting the volume Vi and the recovery volume Vo, the space between the lens 4 and the wafer W in FIG.

 The working distance d of the projection optical system PL is desirably as small as possible in order to allow the liquid 7 to be stably present between the projection optical system PL and the wafer W. However, if the working distance d is too small, the surface of the wafer W may come into contact with the lens 4, so that it is necessary to have a certain margin. Therefore, the working distance d is set to about 2 mm as an example. As described above, since the working distance d is short, the absorption amount of the exposure light is extremely small even if the transmittance of the liquid 7 for the exposure light is somewhat low.

 Next, a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, the present invention is applied to a case where exposure is performed by a step-and-scan type projection exposure apparatus.

FIG. 5 is a front view showing the lower part of the projection optical system PLA of the projection exposure apparatus of this example, the liquid supply device 5, the liquid recovery device 6, and the like, and corresponds to FIG. In FIG. 5 in which the same reference numerals are assigned to the portions, the lowermost lens 32 of the lens barrel 3 A of the projection optical system PLA has a distal end portion 32 A in the Y direction except for a portion necessary for scanning exposure ( (In the non-scanning direction). At the time of scanning exposure, a pattern image of a part of the reticle is projected onto a rectangular exposure area immediately below the tip 32A, and the reticle (not shown) is moved in the X direction (or The wafer W moves in the + X direction (or one X direction) via the XY stage 10 in synchronization with the movement at the speed V in the + X direction).

(/ 3 is the projection magnification). After the exposure of one shot area is completed, the next shot area is moved to the scanning start position by the stepping of the wafer W, and the exposure of each shot area is sequentially performed by the step-and-scan method.

 Also in this example, the liquid 7 is filled between the lens 32 and the surface of the wafer W by applying the liquid immersion method during the scanning exposure. The supply and recovery of the liquid 7 are performed by the liquid supply device 5 and the liquid recovery device 6, respectively.

 FIG. 6 shows the positional relationship between the distal end 32 A of the lens 32 of the projection optical system PLA and the discharge nozzle and the inflow nozzle for supplying and recovering the liquid 7 in the X direction. The shape of the tip 3 2 A of 2 is a long and narrow rectangle in the Y direction, and + three discharges to the X direction side so that the tip 32 A of the lens 32 of the projection optical system PLA is sandwiched in the X direction. Nozzles 21a to 21c are arranged, and two inflow nozzles 23a and 23b are arranged on one X direction side.

Then, the discharge nozzles 21a to 21c are connected to the liquid supply device 5 through the supply pipe 21, and the inflow nozzles 23a and 23b are connected to the liquid recovery device 6 through the recovery pipe 23. It is connected. Also, the discharge nozzles 22a to 22c and the inflow nozzles 23a and 23b are rotated by approximately 180 degrees, and the discharge nozzles 22a to 22c and the inflow nozzles 24a and 2c are arranged. 4b and are arranged. Discharge noise 21a to 21c and inflow nozzles 24a and 24b are alternately arranged in the Y direction, and discharge nozzles 22a to 22c and inflow nozzles 23a and 23b are alternately arranged in the Y direction. The discharge nozzles 22 a to 22 c are connected to the liquid supply device 5 via the supply pipe 22, and the inflow nozzles 24 a and 24 b are connected to the liquid recovery device 6 via the recovery pipe 24.

 When scanning exposure is performed by moving the wafer W in the scanning direction (the X direction) indicated by the solid arrow, the supply pipe 21, the discharge nozzles 21 a to 21 c, the recovery pipe 23, and The liquid 7 is supplied and recovered by the liquid supply device 5 and the liquid recovery device 6 using the inflow nozzles 23a and 23b, and the liquid 7 flows in the X direction so as to fill the space between the lens 32 and the wafer W. . When scanning exposure is performed by moving the wafer W in the direction indicated by the two-dot chain arrow (+ X direction), the supply pipe 22, the discharge nozzles 22a to 22c, the recovery pipe 24, and the inflow nozzle The liquid 7 is supplied and recovered using 24a and 24b, and the liquid 7 flows in the + X direction so as to fill the space between the lens 32 and the wafer W. By switching the direction in which the liquid 7 flows in accordance with the running direction, the tip 32 A of the lens 32 and the wafer W can be scanned in either the + X direction or the 1X direction. Can be filled with the liquid 7, and a high resolution and a wide depth of focus can be obtained.

The supply amount Vi (m ³ / s) of the liquid 7 and the recovery amount Vo (m ³ / s) are determined by the following equations.

 V i = Vo = D sv-v-d (4)

Here, D _SY is the length (m) of the tip 32A of the lens 32 in the X direction. This allows the liquid 7 to stably fill the space between the lens 32 and the wafer W even during scanning exposure.

The number and shape of the nozzles are not particularly limited. For example, supply or recovery of the liquid 7 is performed using two pairs of nozzles on the long side of the tip 32A. It may be. In this case, in order to be able to supply and recover the liquid 7 from either the + X direction or the 1X direction, the discharge nozzle and the inflow nozzle are arranged vertically. Is also good.

 When the wafer W is moved stepwise in the Y direction, the supply and recovery of the liquid 7 are performed from the Y direction, as in the first embodiment.

FIG. 7 shows the positional relationship between the distal end 32 A of the lens 32 of the projection optical system PLA and the discharge nozzle and the inflow nozzle for the Y direction. In FIG. 7, the wafer is not perpendicular to the scanning direction. When stepping in the running direction (one Y direction), supply and recovery of liquid 7 is performed using discharge nozzles 27a and inflow nozzles 29a and 29b arranged in the Y direction. When the wafer is moved stepwise in the + Y direction, the supply and recovery of the liquid 7 is performed using the discharge nozzles 28a and the inflow nozzles 30a and 30b arranged in the Y direction. I do. Further, the supply amount V i (m ³ Z s) of the liquid 7 and the recovery amount V o (m ³ Z s) are determined by the following equations.

 V i = V o = D s xV d (5)

Here, D _sx is the length (m) of the tip _{32 A} of the lens ₃₂ in the Y direction. As in the first embodiment, the liquid 7 is supplied between the lens 32 and the wafer W by adjusting the supply amount of the liquid 7 in accordance with the moving speed V of the wafer W during the step movement in the Y direction. Can be kept satisfied.

 When the wafer W is moved as described above, by flowing the liquid in a direction corresponding to the moving direction, the space between the wafer W and the tip of the projection optical system PL can be continuously filled with the liquid 7. .

The liquid used as the liquid 7 in the above embodiment is not particularly limited to pure water, but has a high refractive index as much as possible because it has transparency to exposure light. Use a material that is stable against the photoresist applied to the surface (for example, Seda Oil) Can be.

 Further, as the liquid 7, a fluorine-based inert liquid which is chemically stable, that is, a liquid having a high transmittance to exposure light and a safe liquid may be used. As this fluorine-based inert liquid, for example, Florinato (trade name of Suriem Co., USA) can be used. This fluorine-based inert liquid is also superior in terms of the cooling effect.

 In addition, the liquid 7 collected in each of the above-described embodiments may be reused. In this case, a filter for removing impurities from the collected liquid 7 is provided in the liquid collection device or the collection pipe. It is desirable to keep.

 Furthermore, the range in which the liquid 7 flows may be set so as to cover the entire projection area (irradiation area of the exposure light) of the reticle's projection image. In controlling such factors, it is desirable that the exposure area be slightly larger than the exposure area and the area be as small as possible as in the above-described embodiments. Since it is difficult to collect all of the supplied liquid using the inflow nozzle, a partition is formed around the wafer, for example, so that the liquid does not overflow from the Z stage, and the liquid in the partition is recovered. It is desirable to provide additional piping.

Further, in each of the above-described embodiments, the liquid 7 flows along the moving direction of the wafer W (XY stage 10). However, the flowing direction of the liquid 7 does not need to match the moving direction. That is, the direction in which the liquid 7 flows may intersect with the direction of movement. For example, when the wafer W is moved in the + X direction, the velocity component in the one X direction of the liquid 7 is zero or a predetermined allowable value. The liquid 7 may be allowed to flow in the following directions. Thus, when exposing a wafer by the step-and-repeat method or the step-and-scan method (both include the step-and-stick method), the moving direction is short (for example, several hundred ms). Change) and follow it By controlling the direction in which the fluid flows, the liquid can be filled between the projection optical system and the wafer. In the step-and-scan projection exposure apparatus, the velocity components in the scanning direction and the non-scanning direction of the XY stage do not become zero in the movement of the wafer between the shot areas, that is, one shot exposure apparatus. After the scanning exposure between the scan areas is completed, the XY stage starts stepping (moving in the non-scanning direction) while the XY stage is decelerating (before the velocity component in the scanning direction becomes zero), and the stepping is performed. Before terminating (before the velocity component in the non-scanning direction becomes zero, for example, during deceleration of the XY stage), the XY stage is started to accelerate in order to scan and expose the next shot area. Control the movement of the stage. Even in such a case, the direction in which the liquid flows can be controlled according to the moving direction of the wafer, and the space between the projection optical system and the wafer can be filled with the liquid.

 The application of the projection exposure apparatus of the present embodiment is not limited to the projection exposure apparatus for semiconductor manufacturing. For example, a projection exposure apparatus for liquid crystal for exposing a liquid crystal display element pattern to a square glass plate, It can be widely applied to a projection exposure apparatus for manufacturing a thin film magnetic head.

 Further, a reticle or a mask used in an exposure apparatus for manufacturing a device for manufacturing a semiconductor element or the like may be manufactured by an exposure apparatus using, for example, far ultraviolet light or vacuum ultraviolet light. The exposure apparatus can be suitably used in a photolithographic process for producing a reticle or a mask.

In addition, a single-wavelength laser in the infrared or visible range oscillated from a DFB semiconductor laser or fiber laser as exposure illumination light is used, for example, by using Erbium (Er) (or both Erbium and Ytterbium (Yb)). ) May be amplified by a fiber-amplifier with a doping, and a harmonic converted to a wavelength of ultraviolet light using a nonlinear optical crystal may be used. The projection optical system PL is a refractive system, as the reflection system and either good _c catadioptric system of the catadioptric system, as for example disclosed in U.S. Patent No. 5 7 8 8 2 2 9 items, a plurality of refractive optical An optical system in which the element and two reflecting optical elements (at least one of which is a concave mirror) are arranged on an optical axis extending straight without being bent can be used. In the exposure apparatus having a reflective refraction system disclosed in this US patent, the optical element closest to the lens, that is, the optical element that comes into contact with the liquid is a reflective optical element. The disclosure of this U.S. patent is incorporated herein by reference, to the extent permitted by the laws designated in this international application or the laws of the selected elected country.

 In addition, an illumination optical system and a projection optical system composed of multiple lenses are incorporated into the exposure apparatus main body to perform optical adjustment, and a reticle stage and wafer stage consisting of many mechanical parts are attached to the exposure apparatus main body to perform wiring and By connecting pipes, installing pipes (supply pipes, discharge nozzles, etc.) for supplying and recovering liquid, and performing comprehensive adjustments (electrical adjustment, operation confirmation, etc.), the projection of this embodiment is achieved. An exposure apparatus can be manufactured. It is desirable to manufacture the projection exposure apparatus in a clean room where the temperature, cleanliness, etc. are controlled.

 The semiconductor device includes a step of designing the function and performance of the device, a step of manufacturing a reticle based on this step, a step of manufacturing a wafer from a silicon material, and a step of manufacturing a reticle by the projection exposure apparatus of the above-described embodiment. It is manufactured through a step of exposing a wafer to a wafer, a step of assembling a device (including a dicing process, a bonding process, and a package process), and an inspection step.

It should be noted that the present invention is not limited to the above-described embodiment, and can take various configurations without departing from the gist of the present invention. Further, including the specification, claims, drawings, and abstract, a Japanese patent application filed on March 26, 1998 The entire disclosure of No. 10—7 926 3 is hereby incorporated by reference in its entirety. Industrial applicability

 According to the first or second projection exposure method of the present invention, since the immersion method is used, the depth of focus of the pattern image of the mask is about n times the depth of focus in air (where n is the liquid used). (Refractive index), and a fine pattern can be stably transferred at a high resolution. Therefore, highly integrated semiconductor devices can be mass-produced at a high yield. When the substrate is moved along a predetermined direction, the projection optical system is moved along the moving direction of the substrate so as to fill the space between the tip of the optical element on the substrate side of the projection optical system and the surface of the substrate. Therefore, when the substrate is moved, the space between the tip of the projection optical system and the surface of the substrate is filled with the liquid, and the liquid immersion method can be used. Further, when foreign matter is attached to the substrate, the foreign matter attached to the substrate can be washed away, and there is an advantage that the yield of the final product can be improved.

 Next, according to the first or second projection exposure apparatus of the present invention, the first or second projection exposure method of the present invention can be performed. In addition, when the supply amount and the recovery amount (flow rate) of the liquid are adjusted according to the moving speed of the substrate stage, even when the moving speed of the stage changes, the tip of the projection optical system is not affected. The amount of the liquid existing between the substrate and the surface can be kept constant <

Claims

The scope of the claims 1. A projection exposure method for illuminating a mask with an exposure beam and transferring the pattern of the mask onto a substrate via a projection optical system,  When the substrate is moved along a predetermined direction, a predetermined distance is set along the moving direction of the substrate so as to fill a space between a tip portion of the optical element on the substrate side of the projection optical system and the surface of the substrate. Projection exposure method, characterized by flowing a liquid.  2. A projection exposure apparatus that illuminates a mask with an exposure beam and transfers a pattern of the mask onto a substrate via a projection optical system.  A substrate stage for holding and moving the substrate, and in a predetermined direction via a supply pipe so as to fill a space between the tip of the optical element on the substrate side of the projection optical system and the surface of the substrate. A liquid supply device for supplying a predetermined liquid along the discharge pipe, and a discharge pipe arranged so as to sandwich the irradiation area of the exposure beam in the predetermined direction together with the supply pipe from the surface of the substrate to the liquid. And a liquid recovery device for recovering  A projection exposure apparatus for supplying and recovering the liquid when the substrate stage is driven to move the substrate along the predetermined direction.  3. The projection exposure apparatus according to claim 2, wherein  A second pair of supply pipes and a discharge pipe are provided, wherein the pair of supply pipes and the discharge pipes are substantially rotated by 180 °. Projection exposure equipment.  4. The projection exposure apparatus according to claim 2 or 3, wherein The projection exposure apparatus is of a scanning exposure type that performs exposure by synchronously moving a mask and a substrate with respect to the projection optical system, and the predetermined direction is the scanning exposure time. A projection exposure apparatus characterized by being in a scanning direction of a substrate.  5. The projection exposure apparatus according to claim 2, 3, or 4, wherein  In a direction orthogonal to the predetermined direction, a pair of supply pipes and a pair of supply pipes and a pair of discharge pipes, which are inverted from each other, are provided in an arrangement corresponding to the pair of supply pipes and the discharge pipes. A projection exposure apparatus characterized by the above-mentioned.  6. The projection exposure apparatus according to any one of claims 2 to 5, further comprising a control system that adjusts a supply amount and a recovery amount of the liquid according to a moving speed of the substrate stage. Projection exposure equipment.  7. The projection exposure apparatus according to any one of claims 2 to 6, wherein the liquid supplied to the surface of the substrate is pure water adjusted to a predetermined temperature, or a fluorine-based inert liquid. A projection exposure apparatus, comprising:  8. An illumination system that irradiates an exposure beam onto the mask, a projection optical system that transfers an image of the pattern of the mask onto a substrate, a substrate stage that holds and moves the substrate, and the substrate of the projection optical system A liquid supply device that supplies a predetermined liquid along a predetermined direction via a supply pipe so as to fill a space between the tip of the optical element on the side and the surface of the substrate; A liquid collecting device for collecting the liquid from the surface of the substrate via a discharge pipe arranged so as to sandwich the irradiation region of the exposure beam in a predetermined direction, in a predetermined positional relationship. Manufacturing method of projection exposure equipment. 9. A method for manufacturing a device using the projection exposure method according to claim 1, comprising an exposure step of illuminating a mask with an exposure beam and transferring a pattern of the mask onto a substrate via a projection optical system. In the exposing step, when the substrate is moved along a predetermined direction, the substrate is filled so as to fill a space between the tip of the optical element on the substrate side of the projection optical system and the surface of the substrate. Manufacturing a device characterized by flowing a predetermined liquid along a moving direction of the device. Construction method.  10. A projection exposure method for illuminating a mask with an exposure beam and exposing a substrate with the exposure beam via a projection optical system.  A projection exposure method characterized by flowing a liquid so as to fill a space between the projection optical system and the substrate, and changing a flowing direction of the liquid in accordance with a moving direction of the substrate.  11. The projection exposure method according to claim 10, wherein  When the supply speed of the liquid is divided into a first component in the moving direction of the substrate and a second component orthogonal to the moving direction, a predetermined value is set when the first component is in a direction opposite to the moving direction of the substrate. A projection exposure method, wherein the liquid is caused to flow so as to have a size equal to or smaller than the allowable value.  12. The projection exposure method according to claim 10, wherein  A projection exposure method characterized by flowing the liquid in the same direction substantially along the moving direction of the substrate.  1 3. The projection exposure method according to claim 1, wherein  A projection exposure method, wherein the substrate is exposed by a step-and-repeat method or a step-and-scan method, and the liquid is flowed substantially along a stepping direction of the substrate.  14. The projection exposure method according to claim 12 or 13, wherein  The mask and the substrate are relatively moved with respect to the exposure beam, and the substrate is scanned and exposed with the exposure beam, and the liquid flows substantially along the scanning direction of the substrate during the scanning exposure. A projection exposure method characterized in that: 15. The projection exposure method according to any one of claims 10 to 14, wherein the flow rate of the liquid is adjusted according to a moving speed of the substrate. 16. A device manufacturing method including a lithographic process including a step of transferring a device pattern onto a substrate by using the projection exposure method according to any one of claims 10 to 15. .  17. A projection exposure apparatus that illuminates a mask with an exposure beam and transfers the image onto a substrate with the exposure beam via a projection optical system.  A projection exposure method, comprising: a liquid supply device configured to flow a liquid so as to fill a space between the projection optical system and the substrate, and to change a flowing direction of the liquid according to a moving direction of the substrate.  18. The projection exposure apparatus according to claim 17, wherein  When the supply speed of the liquid is divided into a first component in the moving direction of the substrate and a second component orthogonal to the moving direction, the liquid supply device is configured such that the first component is in a direction opposite to the moving direction of the substrate. A projection exposure apparatus wherein the liquid is caused to flow so as to have a size equal to or smaller than a predetermined allowable value.  19. The projection exposure apparatus according to claim 18, wherein:  A projection exposure apparatus, wherein the substrate is exposed by a step-and-repeat method or a step-and-scan method, and wherein the liquid supply device flows the liquid substantially along a stepping direction of the substrate. 20. The projection exposure apparatus according to any one of claims 17 to 19, further comprising: a stage system configured to relatively move the mask and the substrate with respect to the exposure beam, respectively. A projection exposure apparatus, characterized in that the liquid supply device flows the liquid substantially along the moving direction of the substrate during scanning exposure of the substrate.  21. The projection exposure apparatus according to any one of claims 17 to 20, further comprising a liquid recovery device that recovers a liquid supplied between the projection optical system and the substrate. A projection exposure apparatus characterized by the above-mentioned. 22. The projection exposure apparatus according to claim 21, wherein: A projection exposure apparatus, wherein a supply port of the liquid supply device and a recovery port of the liquid recovery device are arranged with an irradiation area of the exposure beam interposed therebetween.