JP4591093B2 - Scanning exposure method - Google Patents

Description

  The present invention relates to a scanning exposure method. More specifically, the present invention relates to an immersion type scanning exposure method capable of performing high-precision exposure on a substrate.

  In the manufacture of semiconductor elements and the like, for example, by applying a photoresist on a substrate such as a silicon wafer to form a photoresist film, and developing it after irradiating it with exposure light through a mask having a predetermined pattern, An exposure technique for forming a predetermined resist pattern on a substrate is applied. Specifically, for example, exposure is performed by an exposure method of a stepper method or a scanning method (step-and-scan method) that transfers to each shot region on a substrate on which a photoresist film is disposed ( For example, see Patent Document 1).

  For example, in a scanning exposure method using a scanning method, as shown in FIG. 4, a mask 111 on which a pattern of a predetermined shape is formed is illuminated with exposure light 112, and an image of the mask 111 is, for example, 4: 1. An image is formed on the substrate 114 installed on the stage 116 via the projection optical system 113. A slit 115 is disposed between the mask 111 and the projection optical system 113, and the projection area of the mask 111 is limited by the presence of the slit 115, and the limited projection area is exposed on the substrate 114. The Since the projection area is also moved by scanning the mask 111, the entire area (pattern area) where the pattern on the mask 111 is formed is scanned by scanning the substrate 114 in synchronization with the scanning of the mask 111. The image can be transferred onto the image 114.

  FIG. 5 is an explanatory diagram showing the order of exposure in each region on the substrate and the direction in which the slit is scanned when the substrate (for example, a silicon wafer) is exposed in the conventional scanning exposure method. In the substrate 114 shown in FIG. 5, the pattern of the mask 111 (see FIG. 4) is transferred, and the scanning exposure is performed in the order of performing the region (exposure region) where each becomes one or a plurality of semiconductor chips. Numbers a to p (hereinafter referred to as exposure areas a to p) are given. In FIG. 5, the arrows shown in the exposure area a to the exposure area p indicate the direction in which the substrate 114 is scanned, that is, the direction in which the stage 116 (see FIG. 4) on which the substrate 114 is installed is substantially driven. . For example, when exposing the substrate 114, the exposure area a to be exposed first scans the substrate 114 in the right direction in the drawing as indicated by the arrow in the exposure area a, and the exposure area b to be exposed second is the left The exposure area c to be exposed third is the right direction, and the exposure is performed on all the exposure areas while changing the scanning direction of the substrate 114 in order. By using such a method, as shown in FIG. 4, when scanning and exposing each exposure region on the substrate 114, there is no waste in the scanning path, and a stage 116 and a mask for scanning the substrate 114. It is possible to move the lens 111 with the shortest distance, and it is possible to scan relatively accurately in a short time, so that high-precision exposure is realized.

  On the other hand, the theoretical limit value of the resolution of the projection optical system used in the exposure apparatus becomes higher as the exposure wavelength used is shorter and the numerical aperture (NA) of the projection optical system is larger. For this reason, with the miniaturization of the integrated circuit pattern size, the exposure wavelength, which is the wavelength of radiation used in the exposure apparatus, has become shorter year by year, and the numerical aperture of the projection optical system has also increased. Up to now, we have responded to the demand for miniaturization of integrated circuits by shortening the wavelength of the exposure light source and increasing the numerical aperture, and now mass production of 90 nm (half pitch) using an ArF excimer laser (wavelength 193 nm) as the exposure light source. For advanced integrated circuits, this is being investigated.

However, it is said that the next generation 65 nm (half pitch) or 45 nm (half pitch), which has been further miniaturized, is difficult to achieve only by using an ArF excimer laser. Therefore, for these next-generation technologies, the use of short-wavelength light sources such as F ₂ excimer laser (wavelength 157 nm), EUV (wavelength 13 nm), etc. has been studied. However, the technical difficulty of using these light sources is high. Currently, it is difficult to use.

  In a conventional exposure apparatus, the space between the substrate and the projection optical system is filled with air having a refractive index of 1. At this time, it has been reported that when the space between the substrate and the projection optical system is filled with a medium having a refractive index n, the depth of focus is expanded more than the refractive index. In addition, it is known that an optical system having a large NA that cannot be realized in the case of air can be realized by using a liquid, so that the resolving power is improved.

  The projection exposure method that can increase the NA of the optical system for exposure to 1 or more, transfer a finer pattern, or increase the depth of focus is called an immersion type method. An exposure apparatus using an immersion method is disclosed (for example, see Patent Documents 2 to 4).

As such an immersion type exposure apparatus, for example, as described in Patent Document 3, a mask is illuminated with an exposure beam (exposure light), and the exposure beam is irradiated onto the substrate via a projection optical system. In a projection exposure apparatus that exposes to a liquid, a liquid is supplied so as to fill a space between the projection optical system and the substrate, and a liquid supply device that changes a direction in which the liquid flows according to a moving direction of the substrate. An immersion type exposure apparatus can be mentioned. When the above-described scanning exposure method is performed using such an immersion type exposure apparatus, the liquid is supplied in the same direction as the direction in which the substrate is scanned (the direction in which the stage is driven). Thereby, generation | occurrence | production of the bubble at the time of supply of a liquid and entrainment of a bubble can be suppressed. For this reason, it is common for the substrate scanning direction and the liquid supply direction to be the same direction, and in order to achieve a high throughput of the exposure apparatus, the substrate scanning by driving the stage is more effective. The order in which each exposure area on the substrate is exposed is selected so as to reduce the number.
Japanese Patent Laid-Open No. 11-265849 JP-A-10-303114 International Publication No. 99/49504 Pamphlet JP 2004-207711 A

  However, in the scanning exposure method using the immersion method, when an area including the outer peripheral portion of the substrate is exposed, an abrupt step in the outer peripheral portion of the substrate (for example, a step corresponding to the thickness of the substrate). Depending on the direction in which the liquid is supplied, the necessary liquid cannot be supplied between the substrate and the projection optical system, so that immersion exposure cannot be realized, or the flow of the supplied liquid is disturbed and stable. There were problems such as the inability to realize laminar liquid flow. That is, the flow of the liquid passing through the space between the substrate and the projection optical system is disturbed, and the liquid contains bubbles due to a large disturbance of the liquid flow due to a sudden step, so that the liquid is homogeneous. There is a problem that normal exposure cannot be performed. In addition, when exposure is performed by an immersion method, an upper layer film (also referred to as a top coat) may be provided on the photoresist film so that components of the photoresist film on the substrate do not elute into the liquid. However, the photoresist film may be exposed at the outer peripheral portion of the substrate. For this reason, when the liquid passes through the outer periphery of the substrate, the photoresist film components are eluted into the liquid, so that the impurity concentration in the liquid changes and the transmittance of the exposure light changes slightly. There is a problem that the uniform dimensional resolution of the exposed region is deteriorated because the dose amount is locally changed. In addition, when such a liquid containing impurities adheres to the lens of the projection optical system, there is a concern that the lens of the projection optical system is contaminated and the life of the lens is remarkably reduced.

  The present invention has been made in view of the above-described problems of the prior art, and provides an immersion type scanning exposure method capable of performing high-precision exposure on a substrate.

[1] A projection optical system that limits a mask on which a pattern to be projected onto a substrate is formed with a slit having a predetermined width, scans the substrate relative to the mask, and projects exposure light that has passed through the slit; And an immersion-type scanning exposure method for sequentially forming the pattern in a plurality of regions on the substrate via a liquid supplied to a space between the projection optical system and the substrate, When scanning and exposing a region including the outer peripheral portion of the substrate (outer peripheral region), the substrate includes the center of the substrate and from the side close to the central axis of the substrate perpendicular to the direction of scanning the substrate, When relatively scanning toward the outer peripheral side of the substrate and exposing a region other than the outer peripheral region on the substrate, it coincides with the optical axis of the exposure light of the projection optical system and the substrate adjusted while exposing the relative position in the direction Performed, when exposing the peripheral area on the substrate, by fixing the relative position of the direction which is coincident with the optical axis of the exposure light between the substrate and the projection optical system, or, previous And performing exposure while adjusting the relative position of the projection optical system and the substrate in the direction that coincides with the optical axis of the exposure light based on the information obtained by exposing the region or the adjacent region, and the liquid, A scanning exposure method in which the substrate is supplied from a side close to the central axis, passes through the space between the projection optical system and the substrate, and is collected on the outer peripheral side of the substrate.

[ 2 ] The scanning exposure method according to [1 ], wherein the liquid supplied to the space between the projection optical system and the substrate is water.

[ 3 ] The scanning exposure method according to [1 ], wherein the liquid supplied to the space between the projection optical system and the substrate is an organic liquid having a higher refractive index than water.

  According to the scanning exposure method of the present invention, the substrate is scanned relative to the mask, and sequentially into a plurality of regions on the substrate via the projection optical system and the liquid filled between the projection optical system and the substrate. When performing immersion type scanning exposure in which exposure is performed, exposure can be performed with high accuracy, particularly in a region including the outer peripheral portion of the substrate.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to these embodiments, and may be appropriately selected based on ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. It should be understood that changes, modifications, etc. may be made.

  FIG. 1 is an explanatory view schematically showing an exposure process of an embodiment of the scanning exposure method of the present invention, and FIG. 2 is a substrate in an embodiment of the scanning exposure method of the present invention. It is explanatory drawing which shows the direction which scans. In FIG. 1, a holding means 2 (for example, a stage) for holding a substrate 5, a mask 12 on which a predetermined pattern is formed, an illumination optical system 11 for illuminating exposure light on the mask 12, and a mask 12 are predetermined. A projection optical system 13 for irradiating exposure light for projecting a predetermined pattern onto the substrate 5 held by the holding means 2, and the substrate 5 and the projection optical system held by the holding means 2 13 shows an example in which the exposure apparatus 1 provided with the liquid supply means 4 for filling the liquid 7 in the space 6 between them is used. In FIG. 1, the direction coinciding with the optical axis of the exposure light is the Z direction, the scanning direction in which the mask 12 and the substrate 5 are synchronously moved is the X direction, and the direction orthogonal to the scanning direction is the Y direction. .

  In the scanning exposure method of the present invention, as shown in FIG. 1, a mask 12 on which a pattern to be projected onto a substrate 5 is limited by a slit 3 having a predetermined width (about 7 mm). This is a scanning exposure method in which a pattern is sequentially formed in a plurality of regions on the substrate 5 by scanning relatively, and a liquid 7 is supplied to the space 6 between the projection optical system 13 and the substrate 5. This is an immersion type scanning exposure method in which exposure is performed via the projection optical system 13 and the liquid 7 supplied to the space 6 between the projection optical system 13 and the substrate 5. Since the scanning exposure method of the present embodiment employs immersion type projection exposure, the depth of focus of the pattern image of the projection optical system 13 is expanded to about n times or more of the depth of focus in the air. Since a high NA can be realized, a pattern such as a fine circuit can be formed with high resolution.

  In the scanning exposure method of the present embodiment, as shown in FIGS. 1 and 2, when scanning and exposing a region (outer peripheral region) including the outer peripheral portion of the substrate 5, the substrate 5 is The projection optical system 13 and the substrate 5 are scanned relative to the mask 12 from the side near the center axis 9 of the substrate 5 that includes the center and is orthogonal to the scanning direction of the substrate 5 toward the outer peripheral side of the substrate 5. The liquid 7 to be supplied to the space 6 is supplied from the side close to the central axis 9 of the substrate 5, passes through the space 6 between the projection optical system 13 and the substrate 5, and on the outer peripheral side of the substrate 5. This is a scanning exposure method to be collected. The arrows on the substrate 5 shown in FIG. 2 indicate the direction of scanning the substrate 5 and the direction of supplying the liquid 7 (see FIG. 1). The number of exposure areas on the substrate 5 and the shape to be divided are not particularly limited, and can be appropriately selected depending on the size of the substrate 5, the size of the exposure area (that is, the size of the chip to be formed), and the like. The substrate 5 in the scanning exposure method of the present embodiment is, for example, a silicon wafer, a glass plate for a display element such as a liquid crystal, a ceramic wafer for a thin film magnetic head, or synthetic quartz used in an exposure apparatus. Refers to masks and reticles.

  Conventionally, in a scanning exposure method using an immersion method, when an area including an outer peripheral portion of a substrate is exposed, the substrate is supplied between the substrate and the projection optical system due to a steep step in the outer peripheral portion of the substrate. The liquid flow was disturbed, and the exposure conditions changed, so that normal exposure could not be performed. In the scanning exposure method of the present embodiment, as shown in FIGS. 1 and 2, the substrate 5 is scanned from the side close to the central axis 9 of the substrate 5 toward the outer peripheral side of the substrate 5, The liquid 7 supplied to the space 6 between the projection optical system 13 and the substrate 5 is supplied from the side close to the central axis 9 of the substrate 5, and passes through the space 6 between the projection optical system 13 and the substrate 5. By collecting on the outer peripheral side of the substrate 5, exposure can be performed while maintaining the flow of the liquid 7 in the space 6 in a more normal state at least on the substrate 5. When performing sequential exposure on a plurality of regions on the substrate 5, the continuity of exposure is important. For example, when normal exposure is not performed on the outer peripheral side of the substrate 5, pattern skipping due to pattern thinning is performed. May occur and cause defects, and may adversely affect other adjacent areas. In the scanning exposure method of the present embodiment, since the accuracy in the region including the outer peripheral portion of the substrate 5 that is not so high in the exposure accuracy in the conventional exposure method can be improved, the substrate of the same size The number of chips that can be manufactured from 5 can be increased to improve the yield. In FIG. 2, arrows indicating the direction of scanning the substrate 5 are shown for all the outer peripheral regions on the substrate 5, but in the scanning exposure method of the present embodiment, all of these are shown. It is not always necessary to perform exposure in the outer peripheral region. That is, it is only necessary to appropriately select the outer peripheral area where the exposure is actually performed in accordance with the state of the substrate 5 and the like, the exposure conditions, and the like, and to determine the direction in which the substrate 5 is scanned in these outer peripheral areas.

  Also, in the scanning exposure method using the conventional immersion method, the liquid is contaminated when the liquid passes through the outer peripheral portion of the substrate, or impurities are eluted into the liquid. However, in the scanning exposure method according to the present embodiment, the liquid 7 is applied to the substrate. Since the liquid 7 is contaminated because it flows toward the outer peripheral side of the liquid 5, the liquid 7 does not pass over the substrate 5 again, and the contamination of the lens of the substrate 5 and the projection optical system 13 is effectively prevented. be able to.

  In the predetermined exposure region, if the side where the scanning of the substrate 5 starts and the side where the scanning ends cross the central axis 9 of the substrate 5, the scanning may be performed in either direction.

Further, in the scanning exposure method of the present embodiment, when exposing an area other than the outer peripheral area on the substrate 5, the projection optical system 13 and the substrate 5 are relative to each other in order to optimize the focus. When the exposure is performed while adjusting the general position, that is, the position in the Z direction, and the outer peripheral area on the substrate 5 is exposed, the relative position between the projection optical system 13 and the substrate 5 is fixed, or Based on the information obtained by exposing the previous area (specifically, the previous exposed area) or the adjacent area, specifically, information in the Z direction in these areas, the projection optical system 13 and It intends line exposure while adjusting the relative positions of the substrate 5.

  Conventionally, when performing scanning exposure, the relative position between the projection optical system 13 and the substrate 5 is adjusted in order to reduce the influence on exposure caused by minute unevenness or distortion on the surface of the substrate 5. Exposure was sometimes performed. By performing exposure in this way, it is possible to improve the accuracy of exposure. However, when an area including the outer peripheral portion of the substrate 5 is exposed, it is difficult to adjust the relative position of the projection optical system 13 and the substrate 5 because there is a portion where the substrate 5 does not exist in this exposure area. In such an area, since exposure is actually performed in order to obtain continuity of exposure, it may not actually be used as a chip. Therefore, when the outer peripheral area on the substrate 5 is exposed, Accurate position adjustment may not be necessary. For this reason, when the outer peripheral area on the substrate 5 is exposed, the relative position in the Z direction between the projection optical system 13 and the substrate 5 is fixed, or information on the previous area exposed or adjacent By performing exposure while adjusting the relative position of the projection optical system 13 and the substrate 5 in the Z direction based on information on the exposed areas, specifically, information on the Z direction in these areas, In addition, the exposure process can be simplified without reducing the exposure accuracy in the region used as a chip. When actually performing exposure on a plurality of regions on the substrate 5, for example, first, a normal exposure region that does not include the outer peripheral portion (region that can be used as a chip) is exposed, and then the outer peripheral portion is included. You may expose the exposure area | region (peripheral area | region) which the peripheral part lacked in order.

  As shown in FIG. 1, in the scanning exposure method of the present embodiment, the liquid 7 supplied to the space 6 between the projection optical system 13 and the substrate 5 is supplied to the central axis 9 of the substrate 5 (see FIG. 2). A liquid immersion method called a local fill method (local liquid immersion method), which is supplied from the side close to, passes through the space 6 between the projection optical system 13 and the substrate 5 and is collected on the outer peripheral side of the substrate 5. Used. For this reason, for example, the amount of the liquid 7 to be used can be reduced as compared with an immersion type method called a moving pool method or a simmering stage method in which a substrate is immersed in a liquid as a medium.

  There is no restriction | limiting in particular about the liquid 7 supplied to the space 6 between the projection optical system 13 and the board | substrate 5, You may use water, for example, pure water, and may use the organic substance liquid whose refractive index is higher than water. . Water is a liquid that is inexpensive and easy to obtain, and also excellent in safety. In addition, when an organic liquid having a higher refractive index than water is used, it is possible to further increase the depth of focus and transfer a finer pattern. For example, an alicyclic hydrocarbon compound such as decalin, which is an organic liquid, has a refractive index n of about 1.64 at a wavelength of 193 nm of an ArF excimer laser, and is a liquid for immersion exposure in the next generation immersion type exposure method. Can be suitably used. In addition, since this alicyclic hydrocarbon compound (decalin etc.) is a thing with very little reactivity with a general resist material and calcium fluoride, the acid etc. from the resist film which could have become a problem in pure water Defects in the pattern after development due to elution, and contamination / erosion of the lens are unlikely to occur. Therefore, the yield of electronic devices can be improved, and labor and cost for protection and maintenance of the exposure apparatus can be suppressed.

  Here, the scanning exposure method of the present embodiment will be described in more detail for each step. First, a substrate 5 for performing exposure as shown in FIGS. 1 and 2 is prepared. The substrate 5 used in the scanning exposure method of the present embodiment is a silicon wafer, and an etching target film is often formed on the silicon wafer. A substrate 5 on which a photoresist film is formed by applying a photoresist to the surface of the substrate 5 is used. Note that the substrate 5 used in the scanning exposure method of the present embodiment is not particularly limited. However, the substrate 5 is simply disposed below the photoresist film (between the surface of the substrate 5 and the photoresist film). An underlayer film composed of one or a plurality of films may be disposed, and the surface of the photoresist film may be eluted, for example, into a liquid supplied to a space between the substrate and the projection optical system. An upper film made of a non-material may be formed. The material of the upper layer film is preferably a material that is sufficiently transmissive to the wavelength of exposure light and does not cause intermixing with the photoresist film. The method for forming the photoresist film, the lower layer film, the upper layer film and the like is not particularly limited, but can be formed by, for example, a spin coating method. In the case of a silicon wafer, a coating film such as a photoresist film is often removed about 2 mm in the outer peripheral portion of the substrate 5 (silicon wafer). By doing in this way, the contamination to the robot arm etc. which contact the outer peripheral part of the board | substrate 5 is reduced.

  As shown in FIG. 1, such a substrate 5 is held on a holding means 2 (for example, a stage) of the exposure apparatus 1, and after measuring the positional relationship and rotation using an alignment mark or the like, it is placed at a predetermined place. Position. On the other hand, the mask 12 on which a pattern corresponding to a predetermined resist pattern is formed is held on the mask stage 16 of the exposure apparatus 1.

  The holding means 2 is configured to be able to accurately move the held substrate 5 in a predetermined direction by an arbitrary distance so that exposure can be sequentially performed for each predetermined area on the substrate 5. It is preferable that a holding unit used in a conventionally known exposure apparatus can be suitably used. The holding means 2 shown in FIG. 1 supports a Z stage 18 that controls the position and tilt angle in a direction (Z direction) that coincides with the optical axis of the exposure light, and supports the Z stage 18 in a plane perpendicular to the Z direction. In this case, the XY stage 19 that can be driven in a scanning direction (X direction) in which the mask 12 and the substrate 5 move synchronously and a direction (Y direction) orthogonal to the scanning direction, and the XY stage 19 are supported. A base 20 is included. The substrate 5 is held on a Z stage 18 by being held by a substrate holder (not shown) that fixes its back surface by suction or the like. Although not shown, the holding unit 2 includes a movable mirror and a laser interferometer for measuring the position of the Z stage 18, a stage driving unit for driving the Z stage 18 and the XY stage 19, and the stage. You may further have a control part etc. for controlling a drive part etc.

  The Z stage 18 controls the focus position and tilt angle in the Z direction to adjust the surface of the substrate 5 to the image plane of the projection optical system 13 by autofocusing and autoleveling. Positioning in the X direction and Y direction is performed. The two-dimensional position and rotation angle of the Z stage 18 are measured by a laser interferometer (not shown) as the position of a movable mirror (not shown), and a control unit (not shown) is based on the obtained measurement result. ) Is sent to a stage drive unit (not shown), and the stage drive unit (not shown) drives the Z stage 18 and the XY stage 19.

  Next, the liquid 7 is supplied to a region where exposure is performed on the substrate 5 by the liquid supply means 4 for supplying the liquid 7, and the liquid 7 is supplied to the space 6 between the substrate 5 and the projection optical system 13. Pass through. In FIG. 1, the liquid supply unit 4 supplies the liquid 6 to the space 6 between the substrate 5 and the projection optical system 13, and supplies the liquid 7 in parallel with the scanning direction of the substrate 5. For example, the liquid supply unit 14 includes a supply tank 21 that stores the liquid 7 and a supply channel 23 that serves as a channel for the supplied liquid 7. In addition, the liquid recovery unit 15 includes a recovery tank 22 that stores the recovered liquid 7 and a recovery flow path 24 that is a flow path of the recovered liquid 7. The liquid 7 is supplied from the liquid supply unit 14 via the supply channel 23 to the space 6 by a predetermined amount per unit time, and similarly, the predetermined amount per unit time is supplied to the liquid recovery unit 15 via the recovery channel 24. Collected. Thereby, the liquid 7 is filled in the space 6 between the front end surface of the projection optical system 13 and the substrate 5. Note that the supply flow path and the recovery flow path are opposite to the supply flow path 23 and the recovery flow path 24 as illustrated in FIG. For supplying the liquid 7 in the direction of (from left to right in FIG. 1), a second supply channel 25 having three ends, and a second recovery having two ends. A flow path 26 is disposed. The supply channels 23 and the recovery channels 24 are alternately arranged in the Y direction, and the second supply channels 25 and the second recovery channels 26 are alternately arranged in the Y direction. The second supply channel 25 is connected to the liquid supply unit 14 in the same manner as the supply channel 23, and the second recovery channel 26 is connected to the liquid recovery unit 15.

  In the scanning exposure method of the present embodiment, for example, as shown in FIG. 1, when the outer peripheral portion of the substrate 5 is included in one exposure region on the substrate 5 described above, the substrate 5 is replaced with the substrate 5. 2, and relatively scans toward the outer peripheral side of the substrate 5 from the side close to the central axis 9 (see FIG. 2) of the substrate 5 that is orthogonal to the direction in which the substrate 5 is scanned. 5 is supplied from the side near the central axis 9 (see FIG. 2), passes through the space 6 between the projection optical system 13 and the substrate 5, and is collected on the outer peripheral side of the substrate 5. As described above, in the present embodiment, the shape of the substrate 5 is confirmed for each region to be exposed, and the outer peripheral portion of the substrate 5 is included (for example, there is a region in which the substrate 5 is not part of the exposure region). Etc.), the respective directions described above are determined. The direction in which the liquid 7 is supplied is basically the same as the direction in which the substrate 5 is scanned, and the direction in which the liquid 7 is supplied and the scanning direction of the substrate 5 are determined simultaneously. In the case where the outer peripheral portion of the substrate 5 is not included in the region to be exposed, the state of the surrounding exposure region is taken into consideration so that the scanning of the substrate 5 is minimized when performing continuous exposure. It is preferable to determine the scanning direction and the liquid supply direction.

  Next, after illuminating exposure light from the illumination optical system 11, this exposure light is passed through the mask 12, and further limited by the slit 3, and then between the projection optical system 13 and the projection optical system 13 and the substrate 5. It projects on the area | region which performs exposure on the board | substrate 5 through the liquid 7 supplied to the space 6 of this. Thereafter, the substrate 5 is scanned relative to the mask 12 to transfer the entire pattern of the mask 12 to a predetermined exposure area.

  The illumination optical system 11 is an optical system for irradiating the mask 12 with exposure light. For example, the exposure light source, a condenser lens that condenses light by controlling the directivity of light from the exposure light source, and the mask 12 are irradiated. An illumination optical system having a field stop for adjusting the shape of the exposure light can be cited as a suitable example. Further, such an illumination optical system 11 may further include a relay lens, a fly-eye lens, a filter, a diffusion plate, etc., although not shown.

  There is no particular limitation on the type of exposure light emitted from the exposure light source used in the illumination optical system 11, and depending on the photoresist film applied to the substrate 5 and the combination of the photoresist film and its upper layer film, for example, Further, visible light, ultraviolet rays such as g-line and i-line, and far ultraviolet rays such as excimer laser may be used. In particular, in the exposure apparatus 1 of the present embodiment, an ArF excimer laser (wavelength 193 nm) or a KrF excimer laser (wavelength 248 nm) can be suitably used.

  As the mask 12 used in the scanning exposure method of the present embodiment, an exposure mask used in a conventionally known exposure method can be suitably used. The mask 12 may be a reticle disposed in the illumination optical system 11 or the like. The mask 12 used in the exposure apparatus 1 shown in FIG. 1 is held on a mask stage 16 that can move, finely move, and rotate in a predetermined direction for positioning.

  The projection optical system 13 projects and exposes the pattern of the mask 12 onto the substrate 5 at a predetermined projection magnification (for example, 4: 1). For example, the projection optical system 13 includes a plurality of optical elements (for example, a plurality of optical elements disposed inside the lens barrel). , A lens) can be cited as a preferred example. Further, in the exposure apparatus 1 of the present embodiment, among the optical elements constituting the projection optical system 13, at least the optical element on the substrate 5 side is made of glass such as calcium fluoride (CaF) or quartz (fused silica). It is preferably a parallel flat lens made of a lens and detachably disposed inside the lens barrel. With this configuration, the corrosion resistance of the optical element on the substrate 5 side can be improved, and the optical element on the substrate 5 side can be replaced. Note that the projection optical system 13 used in the exposure apparatus 1 may be a reduction system with a projection magnification of less than 1, a magnification system with a projection magnification of more than 1, or an equal magnification system with a projection magnification of 1. Good.

  The slit 3 is for limiting the mask 12 to a predetermined width, and is configured so that the substrate 5 and the mask 12 can be relatively scanned. By thus scanning and exposing the substrate 5 and the mask 12 relative to each other, for example, it is possible to use only an excellent portion with little distortion of the lens of the projection optical system 13 limited by the slit 3. Therefore, higher-precision exposure can be realized. In the scanning exposure method of the present embodiment, the width of the slit 3 is not particularly limited, and can be determined according to the exposure conditions and the type and size of the projection optical system 13.

  After the pattern of the entire mask 12 is transferred to a predetermined exposure area of the substrate 5, the liquid supply unit 14 is stopped and the supply of the liquid 7 is stopped, and after a predetermined time has elapsed (or the liquid 7 is at the tip of the projection optical system 13. The liquid recovery unit 15 is stopped. In this way, the exposure of the predetermined area on the substrate 5 is finished, the substrate 5 is moved to the start position in another exposure area, and the above-described steps are repeated again.

  As described above, in the scanning exposure method of the present embodiment, the substrate 5 includes the center of the substrate 5 and the substrate when the region (outer peripheral region) including the outer peripheral portion of the substrate 5 is scanned and exposed. 5 is scanned relatively from the side close to the central axis 9 (see FIG. 2) of the substrate 5 perpendicular to the scanning direction to the outer peripheral side of the substrate 5, and the liquid 7 is scanned with the central axis 9 ( Since the liquid 7 is supplied from the side close to (see FIG. 2), passes through the space 6 between the projection optical system 13 and the substrate 5, and is collected on the outer peripheral side of the substrate 5, the liquid 7 is more stable in the projection optics. The space 6 between the system 13 and the substrate 5 can be passed, and a resist pattern can be formed with high accuracy on the substrate 5, particularly in a region including the outer peripheral portion of the substrate 5. Further, even if the liquid 7 is contaminated in the outer peripheral portion, it can be recovered more quickly, and the liquid 7 does not pass over the substrate 5 again after passing through the outer peripheral portion. Contamination of the lens of the projection optical system 13 can be effectively prevented. Note that the exposure order is an exposure area that is not a complete quadrangle including the outer peripheral part using the position information in the Z direction after sequentially exposing the exposure areas that maintain the complete quadrangle in order. ) In order, using the spirit of the present invention.

  Since the scanning exposure method of the present invention can perform exposure on a substrate with high accuracy, it can be used in a method for manufacturing a semiconductor element or the like. In particular, since it is possible to improve the accuracy in the region including the outer peripheral portion on the substrate, for example, the number of chips that can be manufactured in a normal state from the same size substrate can be increased to improve the yield. .

It is explanatory drawing which shows typically the process of the exposure of one Embodiment of the scanning exposure method of this invention. It is explanatory drawing which shows the direction which scans the slit in one Embodiment of the scanning exposure method of this invention. It is explanatory drawing which shows the method of supplying a liquid to the space between a projection optical system and a board | substrate in one embodiment of the scanning exposure method of this invention. It is explanatory drawing explaining the conventional scanning exposure method. It is explanatory drawing which shows the order of the exposure in each area | region on a board | substrate, and the direction which scans a slit at the time of exposing a board | substrate in the conventional scanning exposure method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Exposure apparatus, 2 ... Holding means, 3 ... Slit, 4 ... Liquid supply means, 5 ... Substrate, 6 ... Space, 7 ... Liquid, 9 ... Center axis, 11 ... Illumination optical system, 12 ... Mask, 13 ... Projection Optical system, 14 ... Liquid supply unit, 15 ... Liquid recovery unit, 16 ... Mask stage, 18 ... Z stage, 19 ... XY stage, 20 ... Base, 21 ... Supply tank, 22 ... Recovery tank, 23 ... Supply flow path , 24 ... recovery flow path, 25 ... second supply flow path, 26 ... second recovery flow path, 111 ... mask, 112 ... exposure light, 113 ... projection optical system, 114 ... substrate, 115 ... slit, 116 ... Stage, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p... Exposure region.

Claims (3)

A projection optical system that restricts a mask on which a pattern to be projected onto a substrate is formed with a slit having a predetermined width, scans the substrate relative to the mask, and projects exposure light that has passed through the slit; and An immersion type scanning exposure method for sequentially forming the pattern in a plurality of regions on the substrate via a liquid supplied to a space between the projection optical system and the substrate,
When scanning and exposing a region (outer peripheral region) including the outer peripheral portion of the substrate, the substrate is included from the side near the central axis of the substrate that includes the center of the substrate and is orthogonal to the scanning direction of the substrate. The optical axis of the exposure light of the projection optical system and the substrate, when relatively scanning toward the outer peripheral side of the substrate and exposing a region other than the outer peripheral region on the substrate. When exposure is performed while adjusting the relative position in the matching direction, and the outer peripheral area on the substrate is exposed, the exposure optical axis of the projection optical system and the substrate is aligned with the optical axis of the exposure light. The relative position in the direction matching the optical axis of the exposure light of the projection optical system and the substrate is fixed based on the information obtained by fixing the relative position or exposing the previous area or the adjacent area. The exposure is performed while adjusting the position, and the liquid is added to the base. The supplied from the side near to the central axis, the passed through a space between the substrate and the projection optical system, a scanning exposure method for recovering the outer peripheral side of the substrate.   The scanning exposure method according to claim 1, wherein the liquid supplied to the space between the projection optical system and the substrate is water.   The scanning exposure method according to claim 1, wherein the liquid supplied to the space between the projection optical system and the substrate is an organic liquid having a refractive index higher than that of water.

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