JP2008185908A - Method for manufacturing mask, exposure method, exposure device, and method for manufacturing electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-scanning type exposure device capable of carrying out satisfactory projection exposure using a plurality of projection optical units while suppressing difference in the line width of a pattern image formed in a superposed exposure region via two projection optical units adjacent to each other. <P>SOLUTION: The exposure device forms a superposed exposure region by superposing a part of exposure view fields of a plurality of projection optical units (PL1 to PL11) onto a substrate (P), wherein information relating to the correction value of the line width of a pattern on a mask (M) contributing to formation of the superposed exposure region is obtained and the pattern is formed on the mask on the basis of information of the correction value of the line width. Then the manufactured mask is set to the plurality of projection optical units and the mask pattern is transferred onto the substrate by exposure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a mask manufacturing method, an exposure method, an exposure apparatus, and an electronic device manufacturing method, and in particular, a mask pattern is formed on a photosensitive substrate while moving the mask and the photosensitive substrate relative to a plurality of projection optical units. The present invention relates to a method for manufacturing a mask suitable for a multi-scanning type exposure apparatus that performs projection exposure.

  In recent years, liquid crystal display panels have been widely used as display devices such as televisions. The liquid crystal display panel is manufactured by patterning a transparent thin film electrode on a plate by a photolithography technique. A multi-scanning exposure apparatus is used as an apparatus for projecting and exposing a mask pattern onto a plate in this photolithography process.

  In a multi-scanning exposure apparatus, a mask pattern and projection exposure are performed on a plate while moving a mask and a plate (photosensitive substrate) relative to a projection optical system composed of a plurality of projection optical units (for example, Patent Document 1). See). In the conventional multi-scanning exposure apparatus described in Patent Document 1, the mask pattern is projected onto the plate at the same magnification.

JP 2001-337462 A

  Recently, as the liquid crystal display panel becomes larger, the mask tends to become larger. The mask is very expensive, and the manufacturing cost increases due to the increase in size. Therefore, in order to avoid an increase in the size of the mask, an enlargement system multi-scanning exposure apparatus using a projection optical unit having an enlargement magnification is conceivable. In the magnifying system multi-scanning exposure apparatus, the deflection due to the weight of the mask (hereinafter simply referred to as “mask deflection”) is plate compared to the unit-magnification multi-scanning exposure apparatus that uses a projection optical unit of the same magnification. The effect on the above imaging is increased.

  Specifically, in an enlargement system multi-scanning exposure apparatus, even if focus adjustment is performed for each projection optical unit, due to the influence of mask deflection, the optical axis direction of the imaging plane between two adjacent projection optical units is reduced. The amount of positional deviation tends to increase. As a result, due to this positional deviation amount, the line width of the pattern image formed in the overlapped exposure region via one projection optical unit and the pattern image formed in the overlapped exposure region via the other projection optical unit The difference from the line width becomes larger, and as a result, a good pattern image cannot be obtained.

  The present invention has been made in view of the above-described problems. For example, the present invention is applied to a multi-scanning exposure apparatus that performs projection exposure using a plurality of projection optical units having an enlargement magnification. It is an object of the present invention to provide a method for manufacturing a mask that can suppress a line width difference between pattern images formed in an overlapping exposure region via an optical unit.

  Further, the present invention suppresses a line width difference between pattern images formed in the overlapping exposure region via two projection optical units adjacent to each other, and performs good projection exposure using a plurality of projection optical units. An object of the present invention is to provide a multi-scanning exposure apparatus and exposure method that can be used.

  The present invention also provides an electronic device manufacturing method capable of manufacturing a good electronic device with a large area by using a multi-scanning exposure apparatus that performs good projection exposure using a plurality of projection optical units. The purpose is to do.

In order to solve the above-mentioned problem, in the first embodiment of the present invention, in a method of manufacturing a mask used in an exposure apparatus that forms an overlapped exposure region by overlappingly exposing a part of an exposure field of a plurality of projection optical units on a substrate. ,
Obtaining information on a line width correction value of a pattern in the plurality of pattern areas on the mask that contributes to the formation of the overlapping exposure area;
And a step of forming a pattern on the mask based on the information of the line width correction value.

In the second embodiment of the present invention, in the mask manufacturing method,
Determining the deflection of the mask;
Obtaining information relating to a line width correction value of the mask pattern in accordance with the obtained mask deflection;
And a step of forming a pattern on the mask based on the information of the line width correction value.

In the third aspect of the present invention, in the exposure method of projecting and exposing the pattern of the mask onto the substrate while moving the mask and the substrate relative to the plurality of projection optical units,
A mask manufacturing process for manufacturing the mask by the manufacturing method of the first embodiment;
A mask setting step for setting the mask manufactured in the mask manufacturing step with respect to the plurality of projection optical units;
And an exposure step for exposing the pattern of the mask set in the mask setting step to the substrate.

According to a fourth aspect of the present invention, there is provided a first projection optical unit that forms an image of a first pattern on a mask and a second projection optical unit that forms an image of a second pattern on the mask. In an exposure apparatus that exposes the substrate by partially overlapping the first pattern image and the second pattern image while moving the mask and the substrate relative to the two projection optical units,
An exposure apparatus comprising: a control device that controls at least one light intensity distribution of an exposure field of the first projection optical unit and an exposure field of the second projection optical unit according to the deflection of the mask. provide.

According to a fifth aspect of the present invention, there is provided a first projection optical unit that forms an image of a first pattern on a mask and a second projection optical unit that forms an image of a second pattern on the mask. In an exposure apparatus that exposes the substrate by partially overlapping the first pattern image and the second pattern image while moving the mask and the substrate relative to the two projection optical units,
The first projection is performed such that the line width of the first pattern image and the line width of the second pattern image are equal in an overlapping exposure region on the substrate where the image of the first pattern and the second pattern image overlap. There is provided an exposure apparatus comprising a control device for controlling a light intensity distribution of at least one of an exposure field of an optical unit and an exposure field of the second projection optical unit.

In the sixth embodiment of the present invention, an exposure step of exposing the first and second patterns to the substrate using the exposure apparatus of the fourth or fifth embodiment;
And a development step of developing the substrate that has undergone the exposure step. A method for manufacturing an electronic device is provided.

In a seventh aspect of the present invention, in a method of manufacturing an electronic device using an exposure apparatus that forms an overlapped exposure region by overlappingly exposing a part of an exposure field of a plurality of projection optical units on a substrate,
Setting a correction mask in which the line width of the pattern in the plurality of pattern areas on the mask contributing to the formation of the overlapping exposure area is corrected with respect to a design value on the object plane of the plurality of projection optical units;
Controlling the light intensity distribution in at least one exposure field of the plurality of projection optical units so that line widths of pattern images in the plurality of pattern regions are equal;
And a step of exposing the pattern of the correction mask onto the substrate.

  In the present invention, a pattern on a mask that contributes to the formation of an overlapped exposure region when manufacturing a mask used in an exposure apparatus that forms an overlapped exposure region by overlappingly exposing a part of an exposure field of a plurality of projection optical units on a substrate. Information on the line width correction value is obtained, and a pattern is formed on the mask based on the information on the line width correction value. Specifically, the line width of the mask pattern corresponding to the overlapped exposure region is corrected by a required amount corresponding to the defocus amount of the overlapped exposure region with respect to the imaging plane of the projection optical unit. As a result, by using a mask whose pattern line width is corrected, the difference in line width between pattern images formed in the overlapping exposure region via two adjacent projection optical units can be suppressed to a small value.

  Thus, in the present invention, for example, the present invention is applied to a multi-scanning type exposure apparatus that performs projection exposure using a plurality of projection optical units having an enlargement magnification, and is formed in an overlapping exposure region via two adjacent projection optical units. It is possible to manufacture a mask that can suppress the difference in the line width of the pattern image to be reduced. Therefore, for example, by using the mask manufactured according to the present invention, the difference in the line width of the pattern image formed in the overlapping exposure region via two adjacent projection optical units is suppressed, and a plurality of projection optical units are used. Good projection exposure can be performed. Moreover, a high-precision liquid crystal display element etc. can be manufactured as a favorable electronic device with a large area by favorable projection exposure using the exposure apparatus comprised by this invention.

  Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view schematically showing the overall configuration of an exposure apparatus according to an embodiment of the present invention. In FIG. 1, the X axis is set in the plane of the mask M along the direction (scanning direction) in which the mask M on which a predetermined circuit pattern is formed and the resist-coated plate (photosensitive substrate) P are moved during exposure. The Y axis is set along the direction orthogonal to the X axis (scanning orthogonal direction), and the Z axis is set along the normal direction of the plate P.

  The exposure apparatus of this embodiment includes an illumination system for illuminating a mask M supported in parallel with the XY plane on a mask stage (not shown). The illumination system includes a light source 1 made of, for example, an ultrahigh pressure mercury lamp. The light source 1 is positioned at the first focal position of an elliptical mirror 2 having a reflecting surface made of a spheroid. Therefore, the illumination light beam emitted from the light source 1 forms a light source image at the second focal position of the elliptical mirror 2 via the reflecting mirror (plane mirror) 3. A shutter (not shown) is disposed at the second focal position.

  The divergent light beam from the light source image formed at the second focal position of the elliptical mirror 2 is imaged again via the relay lens system 4. In the vicinity of the pupil plane of the relay lens system 4, a wavelength selection filter (not shown) that transmits only light in a desired wavelength range, for example, light of i-line (365 nm) as exposure light is disposed. In the wavelength selection filter, for example, g-line (436 nm) light, h-line (405 nm), and i-line light can be simultaneously selected, or h-line light and i-line light are simultaneously selected. You can also

  In the vicinity of the position where the light source image is formed by the relay lens system 4, the incident surface of the incident side light guide of the fiber box 5 is positioned. The light beam incident on the incident side light guide of the fiber box 5 propagates through the inside thereof and is then emitted from the eleven exit side light guides. Thus, the fiber box 5 has the same number of incident ends as the number of light sources 1 (one in FIG. 1) and the same number as the number of projection optical units (11 in FIG. 1) constituting the projection optical system. And an injection end.

  A divergent light beam emitted from one typical exit-side light guide of the fiber box 5 is converted into a substantially parallel light beam by a collimator lens 7 a and then enters a fly-eye integrator (optical integrator) 6. The fly-eye integrator 6 is configured, for example, by arranging a large number of positive lens elements vertically and horizontally and densely so that the central axis extends along the optical axis AX. Therefore, the light beam incident on the fly-eye integrator 6 is divided into wavefronts by a large number of lens elements, and a secondary light source (substantially) consisting of the same number of light source images as the number of lens elements on the rear focal plane (that is, near the exit surface). A typical surface light source).

  The light beam from the secondary light source is limited by an aperture stop (not shown) disposed in the vicinity of the rear focal plane of the fly-eye integrator 6 and then enters the condenser lens system 7b. The aperture stop is disposed at a position optically conjugate with the pupil plane of the corresponding projection optical unit, and has a variable aperture for defining the range of the secondary light source that contributes to illumination. The aperture stop changes the aperture diameter of the variable aperture, thereby determining the σ value that determines the illumination condition (secondary on the pupil plane relative to the aperture diameter of the pupil plane of each projection optical unit constituting the projection optical system) The ratio of the diameter of the light source image) is set to a desired value.

  The light flux through the condenser lens system 7b illuminates one area on the mask M on which a predetermined transfer pattern is formed in a superimposed manner. Similarly, divergent light beams emitted from the other light guides on the exit side of the fiber box 5 also pass through one region on the mask M via the collimating lens 7a, the fly-eye integrator 6, the aperture stop, and the condenser lens system 7b. Are illuminated in a superimposed manner. That is, the illumination system illuminates a plurality of areas (for example, 11 in total in FIG. 1) having a predetermined shape, for example, a trapezoidal illumination area, arranged in the Y direction on the mask M.

  In the above-described example, in the illumination system, the illumination light from one light source 1 is equally divided into 11 illumination lights by the fiber box 5, but is limited to the number of light sources and the number of projection optical units. Without limitation, various modifications are possible. That is, if necessary, two or more light sources are provided, and the illumination light from these two or more light sources is equally divided into a required number (the number of projection optical units) of illumination light through a light guide with good randomness. You can also In this case, the fiber box 5 has the same number of incident ends as the number of light sources, and has the same number of exit ends as the number of projection optical units.

  The light transmitted through each of the trapezoidal illumination areas on the mask M is sent from a plurality of (11 in total in FIG. 1) projection optical units PL1 to PL11 arranged along the Y direction so as to correspond to each illumination area. Is incident on the projection optical system. Here, the configurations of the projection optical units PL1 to PL11 are the same. Each of the projection optical units PL1 to PL11 is an optical system that is almost telecentric on both sides (the mask M side and the plate P side).

  In FIG. 1, the reference symbols PL3, PL5, PL7, PL9, and PL11 are not shown for clarity. FIG. 1 shows an example in which a catadioptric optical system is used as each projection optical unit. However, the present invention is not limited to this, and various types of optical systems having a magnification larger than the same magnification, that is, an enlargement magnification, are used. Can be used. That is, as each projection optical unit, a once-imaging optical system having an enlargement magnification, a twice-imaging optical system having an enlargement magnification, or the like can be used.

  However, in the magnifying system multi-scanning type exposure apparatus, it is better to obtain an inverted image by odd-numbered imaging than to form an upright image on the plate by imaging the mask pattern an even number of times. This is desirable because the configuration can be simplified. Hereinafter, in order to simplify the explanation, each projection optical unit is a one-time imaging type optical system having an enlargement magnification, and forms an enlarged inverted image of the pattern of the mask M on the plate P. .

  The light passing through the projection optical system constituted by the plurality of projection optical units PL1 to PL11 forms a mask pattern image on the plate P supported in parallel with the XY plane on a plate stage (not shown). As described above, since each of the projection optical units PL1 to PL11 is configured as an enlargement system, a plurality of trapezoidal exposures arranged in the Y direction so as to correspond to each illumination area on the plate P which is a photosensitive substrate. An enlarged image of the mask pattern is formed in the region.

  The mask stage is provided with a scanning drive system (not shown) having a long stroke for moving the stage along the X direction which is the scanning direction. In addition, a pair of alignment drive systems (not shown) are provided for moving the mask stage by a minute amount along the Y direction, which is the orthogonal direction of scanning, and for rotating the mask stage by a minute amount around the Z axis. The position coordinate of the mask stage is measured by a laser interferometer (not shown) using a movable mirror and the position is controlled.

  A similar drive system is also provided for the plate stage. That is, a scanning drive system (not shown) having a long stroke for moving the plate stage along the X direction, which is the scanning direction, and moving the plate stage by a minute amount along the Y direction, which is the orthogonal direction of scanning. A pair of alignment drive systems (not shown) for rotating a minute amount around the shaft is provided. The position coordinate of the plate stage is measured and controlled by a laser interferometer PIF using a moving mirror.

  A pair of alignment systems (not shown) are arranged above the mask M as means for relatively aligning the mask M and the plate P along the XY plane. As the alignment system, for example, an alignment system in which a relative position between a mask alignment mark formed on the mask M and a plate alignment mark formed on the plate P is obtained by image processing can be used. Further, the plate stage is provided with an illuminance sensor IS for measuring the illuminance on the image plane of each of the projection optical units PL1 to PL11.

  In the magnifying system multi-scanning type exposure apparatus of the present embodiment, a mask is applied to the projection optical system including a plurality of projection optical units PL1 to PL11 by the action of the scanning drive system on the mask stage side and the scanning drive system on the plate stage side. By moving the M and the plate P along the X direction, the entire pattern area on the mask P is transferred (scanned exposure) to the entire exposure area on the plate P.

  FIG. 2 is a diagram for explaining the relationship between a pattern formed on a mask and a pattern image formed on a plate in an enlarged multi-scan exposure apparatus. FIG. 2A shows a pattern formed on the mask. (B) shows the pattern image formed on the plate. In FIG. 2A, in order to simplify the description, five pattern regions PAa to PAe are formed on the mask M at intervals along the Y direction so as to correspond to the five projection optical units. It is assumed that patterns PTa to PTe schematically shown by hatching areas are formed in the pattern areas PAa to PAe, respectively.

  In this case, enlarged pattern images PIa to PIe that are inverted with respect to the Y direction of the patterns PTa to PTe are formed on the plate P as shown in FIG. Here, the + Y direction side of the pattern image PIa and the −Y direction side of the pattern image PIb overlap in the overlap exposure region Lab, and the + Y direction side of the pattern image PIb and the −Y direction side of the pattern image PIc overlap. Overlapping in Lbc, + Y direction side of pattern image PIc and −Y direction side of pattern image PId overlap in overlapping exposure region Lcd, + Y direction side of pattern image PId and −Y direction side of pattern image PIe overlap. Overlapping in the exposure region Lde.

  3A and 3B are diagrams for explaining the focus adjustment of each projection optical unit with respect to the deflection of the mask in the multi-scanning exposure apparatus. FIG. 3A shows a state before focus adjustment, and FIG. 3B shows the state after focus adjustment. It shows a state. In FIG. 3, for easy understanding of the description, seven projection optical units PLa to PLg are arranged adjacent to each other in the Y direction without overlapping each other, and the projection optical units PLa to PLg are almost equal in size. Shall be formed. Before the focus adjustment of the projection optical units PLa to PLg, as shown in FIG. 3A, the image planes of the projection optical units PLa to PLg are also adapted to correspond to the deflection along the Y direction of the mask M. The overall shape is curved along the Y direction.

  In this case, the amount of positional deviation along the Z direction between the image plane of the central projection optical unit PLd and the image planes of the projection optical units PLa and PLg at both ends becomes too large, and the mask pattern is good on the plate P. I can't get a statue. Therefore, in the multi-scanning exposure apparatus, as shown in FIG. 3B, focus adjustment is performed for each projection optical unit, and along the Z direction of the image planes PIa to PIg of the projection optical units PLa to PLg. The amount of misalignment is kept small. Regarding the focus adjustment of the projection optical unit, for example, JP-A-2005-340605, JP-A-2005-331694, JP-A-2001-337463, and the like can be referred to.

  FIG. 4 is a diagram for explaining a state in which the image plane is displaced between adjacent projection optical units even when focus adjustment is performed in an enlargement system multi-scanning exposure apparatus. In FIG. 4, for easy understanding of the description, three projection optical units PL5 to PL7 are arranged side by side along the Y direction, and the projection optical units PL5 to PL7 are inverted with respect to the Y direction of the patterns PT5 to PT7. An enlarged image is to be formed. Referring to FIG. 4, in the magnifying multi-scan exposure apparatus as in the present embodiment, even if focus adjustment is performed for each of the projection optical units PL <b> 5 to PL <b> 7, A large amount of displacement in the optical axis direction (Z direction) of the imaging plane occurs between the projection optical units PL5 and PL6 and between PL6 and PL7.

  Specifically, an overlapping area (corresponding to an overlapping exposure area) between the + Y direction side of the imaging plane IP5 of the projection optical unit PL5 and the −Y direction side of the imaging plane IP6 of the projection optical unit PL6, and the projection optical unit PL7 In the overlapping region (corresponding to the overlapping exposure region) between the −Y direction side of the imaging surface IP7 and the + Y direction side of the imaging surface IP6 of the projection optical unit PL6, the optical surface direction of the imaging surfaces IP5 and IP6 A large amount of misalignment and misalignment in the optical axis direction between the imaging surfaces IP7 and IP6 occur. As a result, the line width of the pattern image formed in the overlapped exposure region via the projection optical units PL5 and PL7 and the overlapped exposure region formed via the projection optical unit PL6 due to the positional deviation amount of the imaging plane. A difference from the line width of the pattern image to be generated is relatively large, and as a result, a good pattern image cannot be obtained on the plate P.

  The magnifying system multi-scanning type exposure apparatus of the present embodiment plates a part of the exposure field (corresponding to the trapezoidal illumination area on the mask M) of a plurality of projection optical units (11 in FIG. 1 exemplarily). It is an exposure apparatus that forms an overlapping exposure region by overlapping exposure on a (substrate). In this embodiment, more generally, the line width difference between the pattern images is reduced so that the line widths of the pattern images formed in the overlapping exposure regions on the plate via the two adjacent projection optical units become equal. Thus, a method for correcting the line width of the pattern on the mask that contributes to the formation of the overlapping exposure region is proposed. Further, the pattern formed in the overlapping exposure region on the plate through two adjacent projection optical units so that the line width of the pattern image formed on the plate through the projection optical unit becomes a desired value. A method is proposed for controlling the light intensity distribution in the exposure field of at least one projection optical unit so that the line width difference of the image becomes small.

  Hereinafter, the basic principle of the present invention will be described prior to specific description of each method of the present embodiment. FIG. 5A is a cross-sectional view of a mask exemplarily used for explaining the basic principle of the present invention, and FIG. 5B is a diagram showing a light transmittance distribution of the mask of FIG. Referring to FIG. 5A, an isolated line pattern ISP is formed on the mask Me. As shown in FIG. 5B, the region where the isolated line pattern ISP is formed is a light shielding region (light transmittance is 0), and the surrounding region excluding the isolated line pattern ISP is a light transmissive region (light The transmittance is 1).

  FIG. 6 is a diagram showing a light intensity distribution of an aerial image formed through the projection optical unit when the mask of FIG. 5 is used. In FIG. 6, the vertical axis represents the relative intensity obtained by normalizing the maximum value of the light intensity to 1, and the horizontal axis represents the position in the direction corresponding to the line width direction of the isolated line pattern ISP of the mask Me by λ / NA. It is a relative position obtained by normalization. Here, λ is the wavelength of light, and NA is the image-side numerical aperture of the projection optical unit.

In FIG. 6, a curve indicated by a solid line denoted by reference numeral 61 indicates the light intensity distribution of the aerial image at the best focus position of the projection optical unit, and a curve indicated by a broken line denoted by reference numeral 62 is from the best focus position. The light intensity distribution of the aerial image at a position defocused by 1/4 of the Rayleigh unit (RU) is shown. Here, the Rayleigh unit RU is a defocus amount corresponding to the focal depth of the projection optical unit, and is represented by RU = λ / (2 × NA ² ).

  A curve indicated by a rough dotted line denoted by reference numeral 63 indicates the light intensity distribution of the aerial image at a position defocused by 1/2 of the Rayleigh unit RU from the best focus position. A curve indicated by a thin dotted line denoted by reference numeral 64 indicates the light intensity distribution of the aerial image at a position defocused by the Rayleigh unit RU from the best focus position. A curve indicated by an alternate long and short dash line with reference numeral 65 indicates the light intensity distribution of the aerial image at a position defocused by 5/4 of the Rayleigh unit RU from the best focus position.

  In FIG. 6, a horizontally extending straight line denoted by reference numeral 66 indicates a relative intensity at which the line width of the aerial image (indicated by reference numeral 67) at the best focus position is 0.74 × λ / NA at the slice level. As shown. That is, in the aerial image simulation of FIG. 6, the k1 factor of the exposure apparatus is assumed to be 0.74. The k1 factor is a coefficient that defines the line width of the pattern image in the exposure apparatus, and is represented by line width = k1 × λ / NA.

FIG. 7 is a diagram showing the change in the line width of the spatial pattern image at each defocus position, and shows the relationship between the line width of the aerial image and the defocus amount. In FIG. 7, the vertical axis represents the relative value of the line width of the spatial pattern image obtained by standardizing the line width at the best focus position to 100%, and the horizontal axis represents the Rayleigh unit RU = λ / (2 × NA ² ). This is the relative value of the defocus amount normalized by. The relationship between the line width of the aerial image and the defocus amount shown in FIG. 7 indicates the defocus amount at each defocus position, the light intensity distribution of the aerial image at each defocus position, and the slice in the aerial image simulation of FIG. It is determined by the line width defined by the horizontal distance of a pair of intersections with level 66.

  Referring to FIG. 7, when the light intensity distribution in the exposure field of two adjacent projection optical units is the same, that is, the slice level is the same for the aerial image formed via the two adjacent projection optical units. In some cases, the line width of the pattern image formed on the plate via each projection optical unit and the design line width of the pattern image (the line width of the pattern image formed on the image plane that is the best focus position) It can be seen that the difference between the two occurs depending on the defocus amount. Therefore, in the first method of the present invention, the line widths of the pattern images formed in the overlapping exposure regions on the plate via the two adjacent projection optical units are made equal to each other (more generally, the line width difference). As shown in FIG. 8, the line width of the pattern on the mask that contributes to the formation of the overlapped exposure region is corrected.

In FIG. 8, the vertical axis represents the relative value of the line width of the mask pattern obtained by standardizing the design line width of the mask pattern to 100%, and the horizontal axis represents the Rayleigh unit RU = λ / ( 2 × NA ² ) relative value of defocus amount normalized. In this way, by correcting the line width of the pattern on the mask that contributes to the formation of the overlapped exposure region by the required amount corresponding to the defocus amount of the overlapped exposure region on the plate with respect to the imaging plane of the projection optical unit, The line width of the pattern image formed in the overlapping exposure region on the plate via the two projection optical units adjacent to each other can be brought close to a desired design value, and thus the line width difference between the pattern images can be kept small. .

  In the above description, by performing a spatial image simulation for calculating the line width of the spatial pattern image formed through the projection optical unit, the line width of the spatial pattern image and the space from the imaging plane of the projection optical unit are calculated. The relationship with the defocus amount of the pattern image is obtained. However, the present invention is not limited to this, and by performing a resist simulation for calculating the line width of the pattern image formed on the resist via the projection optical unit, the line width of the pattern image and the image plane of the projection optical unit are calculated. The relationship with the defocus amount of the pattern image on the resist can be obtained. In addition, by measuring the line width of the pattern image printed on the resist via the projection optical unit, the line width of the pattern image and the defocus amount of the pattern image on the resist from the image plane of the projection optical unit You can also ask for the relationship.

  Referring to FIG. 6 again, when the line width of the mask pattern is not corrected, the slice level for the aerial image formed through the two adjacent projection optical units is changed, that is, the two adjacent projections. It can be seen that by changing the light intensity distribution in the exposure field of the optical unit, the line width of the pattern image formed through each projection optical unit also changes. Therefore, in the second method of the present invention, the line width of the pattern image formed on the plate via the projection optical unit is set to a desired value, particularly on the plate via the two adjacent projection optical units. In order to suppress the difference in the line width of the pattern image formed in the overlapped exposure region, as shown in FIG. 9, the light intensity distribution in the exposure field of at least one projection optical unit according to the deflection of the mask M and thus the projection The light intensity distribution in the exposure area of the optical unit is controlled.

In FIG. 9, the vertical axis represents the relative value of the dose obtained by standardizing the designed light intensity (dose) in the exposure field of the projection optical unit to 100%, and the horizontal axis represents the Rayleigh unit as in FIG. This is the relative value of the defocus amount normalized by RU = λ / (2 × NA ² ). In this way, by controlling the light intensity distribution in the exposure field of the projection optical unit, the line width of the pattern image formed via the projection optical unit can be brought close to a desired design value. The line width difference of the pattern image formed in the overlapping exposure region on the plate via the two projection optical units can be suppressed to a small value.

  FIG. 10 is a flowchart showing each step of the exposure method to which the first method of the present invention is applied. Referring to FIG. 10, in the exposure method of the present embodiment in which the pattern of the mask M is projected and exposed onto the plate P while the mask M and the plate (substrate) P are moved relative to the plurality of projection optical units PL1 to PL11. Information on the line width correction value of the pattern on the mask M that contributes to the formation of the overlapping exposure region is obtained (S11). Specifically, in step S11, for example, the line width of the pattern image formed via the projection optical unit and the projection optics based on the information on the shape of the pattern to be formed on the mask M and the information on the deflection of the mask M. The relationship between the defocus amount of the pattern image from the image plane of the unit is obtained, and information on the line width correction value of the pattern of the mask M corresponding to the overlapping exposure region is obtained from the relationship between the line width of the pattern image and the defocus amount. Ask.

  More specifically, in step S11, for example, a spatial pattern formed via the projection optical unit based on information on the shape of the pattern to be formed on the mask M, information on the deflection of the mask M, and optical characteristics of the projection optical unit. An aerial image simulation for calculating the line width of the image is performed (S11a). Then, the relationship between the line width of the spatial pattern image and the defocus amount of the spatial pattern image from the imaging surface of the projection optical unit is obtained (S11b), and the overlap exposure is performed from the relationship between the line width of the spatial pattern image and the defocus amount. Information about the line width correction value of the pattern of the mask M corresponding to the region is obtained (S11c).

  Next, a pattern is formed on the mask M based on the information on the line width correction value of the mask pattern obtained through step S11 (S12). In this way, steps S11 and S12 constitute a method for manufacturing a mask M used in an exposure apparatus that forms an overlapped exposure region by overlappingly exposing a part of the exposure field of the plurality of projection optical units PL1 to PL11 onto the plate P. is doing. In manufacturing the mask M, information regarding the line width correction value of the pattern of the mask M can be obtained by performing a resist simulation or actually performing baking on the resist. Further, if necessary, information on the line width correction value of the pattern of the mask M corresponding to the area other than the overlapping exposure area is obtained, and the pattern is corrected to the mask M that contributes to the formation of the area other than the overlapping exposure area. it can.

  Next, the mask M manufactured in the mask manufacturing process (S11, S12) is set for the plurality of projection optical units PL1 to PL11 (S13). Finally, the pattern of the mask M set in the mask setting step S13 is exposed to the plate P (S14). In the exposure method of the present embodiment to which the first technique is applied, a mask M that can suppress a line width difference between pattern images formed in the overlapping exposure region via two adjacent projection optical units is used. Therefore, good projection exposure can be performed using the plurality of projection optical units PL1 to PL11, and thus a good electronic device with a large area can be manufactured.

  FIG. 11 is a view schematically showing a main configuration of an exposure apparatus to which the second method of the present invention is applied. In the magnifying system multi-scanning type exposure apparatus of the present embodiment, as shown in FIG. 11, the light intensity distribution in the exposure field of the projection optical unit is positioned immediately before the mask M in the optical path of the required projection optical unit. A density filter (transmittance filter) 11 for defining (controlling) is disposed. The transmittance distribution of the density filter 11 is determined so that the line width of the pattern image formed in the exposure area on the plate P via the projection optical unit becomes a desired design value.

  That is, the transmittance distribution of the density filter 11 is determined from the line width of the pattern image formed in the exposure region on the plate P via the projection optical unit when the density filter 11 is not interposed, and the image plane of the projection optical unit. It is determined based on the relationship with the defocus amount of the exposure area of the plate P. Here, the relationship between the line width of the pattern image and the defocus amount is determined by the various methods described above in relation to the exposure method of this embodiment, that is, a method for performing aerial image simulation, a method for performing resist simulation, or a resist. It is obtained by a method of measuring the line width of the pattern image printed on the top.

  Specifically, FIG. 4 showing the distribution of the defocus amount of the exposure area on the plate P with respect to the imaging planes IP5 and IP7 of the projection optical units PL5 and PL7, and the exposure field dose necessary to obtain a desired line width. Referring to FIG. 9 showing the relationship between the relative value of the amount and the defocus amount, the transmittance distribution as shown in FIG. 12A is given to the density filter 11 arranged in the optical path of the projection optical units PL5 and PL7. Then, the line width of the pattern image formed on the plate P via the projection optical units PL5 and PL7 can be brought close to a desired design value.

  Similarly, if a transmittance distribution as shown in FIG. 12B is given to the density filter 11 arranged in the optical path of the projection optical unit PL6, it is formed on the plate P via the projection optical unit PL6. The line width of the pattern image can be brought close to a desired design value. However, in the case of the projection optical unit PL6 arranged in the center, the defocus amount of the exposure area on the plate P with respect to the image plane IP6 is relatively small, so the density filter 11 is arranged in the optical path of the projection optical unit PL6. It can be omitted. Although not shown, a density filter to which a required transmittance distribution is provided is also arranged as necessary for projection optical units other than the projection optical units PL5 and PL7.

  As described above, the exposure apparatus according to this embodiment includes the density filter 11 as a light intensity distribution adjusting member in the optical path of a required projection optical unit among the plurality of projection optical units. Therefore, by the action of the density filter 11, the light intensity distribution in the exposure field of the projection optical unit (the light intensity distribution of the illumination light that illuminates the pattern corresponding to the projection optical unit) is changed according to the deflection of the mask M ( The line width of the pattern image formed in the exposure area on the plate P via the projection optical unit can be made close to a desired design value. As a result, a pattern image having a desired line width can be formed on the plate via the projection optical unit.

  In the exposure apparatus of this embodiment, the line widths of the pattern images formed in the overlapping exposure region on the plate P are made equal through the two adjacent projection optical units (or the pattern image formed in the overlapping exposure region). In order to reduce the line width difference between the two, the light intensity distribution of the overlapping area in the exposure field of at least one projection optical unit (the light intensity distribution of the illumination light that illuminates the pattern corresponding to the overlapping area in the exposure field) It is sufficient to provide the density filter 11 with the required transmittance distribution necessary for control.

  By the way, in the main configuration shown in FIG. 11, a density filter 11 as a control device for controlling the light intensity in the exposure field is disposed at a position immediately before the mask M. However, the present invention is not limited to this. In general, the density filter can be set at a position that is optically conjugate with the mask M. For example, as shown in FIG. 13, in the case of a configuration including the mask blind MB and the imaging optical system 12 in the optical path between the condenser lens system 7b and the mask M, as shown by the solid line in the drawing, The density filter 11 can be disposed at the immediately preceding position. Further, as indicated by a broken line in the figure, the density filter 11 can be arranged at a position immediately after the mask blind MB or a position immediately before the mask M.

  In the above description, in order to facilitate understanding, the first method of the present invention is applied to the exposure method, and the second method of the present invention is applied to the exposure apparatus. However, the present invention is not limited to this, and if necessary, the second method is applied to the exposure method, the first method is applied to the exposure apparatus, or the first method and the second method are applied to the exposure method or the exposure apparatus. Can be applied at the same time. In general, it is difficult to continuously change the line width of the mask pattern, and as shown in FIG. 14, it can be changed only in a discrete manner in practice.

  In FIG. 14, as an example, two line patterns 71 and 72 elongated in the scanning direction (X direction) and one line pattern 73 elongated in the scanning orthogonal direction (Y direction) in the overlapping region 70a of the trapezoidal exposure field 70. Shows a state where the line width of the mask pattern is discretely corrected (changed). When applying the first method to the exposure method or the exposure apparatus, it is not always possible to perform a desired correction on the line width of the mask pattern. In this case, if the first method and the second method are used together, the line width of the mask pattern image can be made highly accurate by controlling the light intensity distribution by the amount that cannot be corrected by the mask pattern line width correction (line width bias). Can be controlled.

  In the above description, the first method and the second method of the present invention are applied to the enlargement-type multi-scanning exposure method and exposure apparatus. However, the present invention is not limited to this, and the same applies to a multi-scanning exposure method and exposure apparatus using a plurality of projection optical units having a reduction magnification, and an equal magnification multi-scanning exposure method and exposure apparatus. The first method and the second method of the present invention can be applied.

  Further, in the above description, the relationship between the line width of the pattern image and the defocus amount is obtained for a mask having an isolated line pattern as an example. However, the present invention is not limited to this, and the relationship between the line width of the pattern image and the defocus amount can be obtained for masks having various patterns based on the same concept as described above. By the way, when line and space patterns are mixed in one mask, it is difficult to reduce the line width difference of the pattern image in the overlapped exposure area by only controlling the light intensity distribution for all patterns. Yes, it is necessary to correct the line width of the mask pattern.

  The exposure apparatus according to the present embodiment is assembled by electrically, mechanically, or optically coupling the optical members and the stages in the present embodiment shown in FIG. 1 so as to achieve the functions described above. be able to. Then, the mask is illuminated by the illumination system (illumination process), and the transfer pattern formed on the mask is scanned and exposed on the photosensitive substrate using the projection optical system including the projection optical units PL1 to PL11 (exposure process). Thus, a device (semiconductor element, liquid crystal display element, thin film magnetic head, etc.) can be manufactured. Hereinafter, an example of a technique for obtaining a semiconductor device as a micro device by forming a predetermined circuit pattern on a wafer as a photosensitive substrate using the exposure apparatus of the present embodiment or the exposure method of the present embodiment. This will be described with reference to the flowchart of FIG.

  First, in step 301 of FIG. 15, a metal film is deposited on one lot of wafers. In the next step 302, a photoresist is applied on the metal film on the one lot of wafers. Thereafter, in step 303, using the exposure apparatus of the present embodiment, the image of the pattern on the mask is sequentially exposed and transferred to each shot area on the wafer of one lot via the projection optical system. Thereafter, in step 304, the photoresist on the one lot of wafers is developed, and in step 305, the resist pattern is etched on the one lot of wafers to form a pattern on the mask. Corresponding circuit patterns are formed in each shot area on each wafer.

  Thereafter, a device pattern such as a semiconductor element is manufactured by forming a circuit pattern of an upper layer. According to the semiconductor device manufacturing method described above, a semiconductor device having an extremely fine circuit pattern can be obtained with high throughput. In steps 301 to 305, a metal is deposited on the wafer, a resist is applied on the metal film, and exposure, development, and etching processes are performed. Prior to these processes, on the wafer. It is needless to say that after forming a silicon oxide film, a resist may be applied on the silicon oxide film, and steps such as exposure, development, and etching may be performed.

  In the exposure apparatus of this embodiment, a liquid crystal display element as a micro device can be obtained by forming a predetermined pattern (circuit pattern, electrode pattern, etc.) on a plate (glass substrate). Hereinafter, an example of the technique at this time will be described with reference to the flowchart of FIG. In FIG. 16, in a pattern forming process 401, a so-called photolithography process is performed in which the exposure pattern of this embodiment is used to transfer and expose a mask pattern onto a photosensitive substrate (such as a glass substrate coated with a resist). By this photolithography process, a predetermined pattern including a large number of electrodes and the like is formed on the photosensitive substrate. Thereafter, the exposed substrate undergoes steps such as a developing step, an etching step, and a resist stripping step, whereby a predetermined pattern is formed on the substrate, and the process proceeds to the next color filter forming step 402.

  Next, in the color filter forming step 402, a large number of sets of three dots corresponding to R (Red), G (Green), and B (Blue) are arranged in a matrix or three of R, G, and B A color filter is formed by arranging a plurality of stripe filter sets in the horizontal scanning line direction. Then, after the color filter forming step 402, a cell assembly step 403 is executed. In the cell assembly step 403, a liquid crystal panel (liquid crystal cell) is assembled using the substrate having the predetermined pattern obtained in the pattern formation step 401, the color filter obtained in the color filter formation step 402, and the like.

  In the cell assembly step 403, for example, liquid crystal is injected between the substrate having the predetermined pattern obtained in the pattern formation step 401 and the color filter obtained in the color filter formation step 402, and a liquid crystal panel (liquid crystal cell) is obtained. ). Thereafter, in a module assembling step 404, components such as an electric circuit and a backlight for performing a display operation of the assembled liquid crystal panel (liquid crystal cell) are attached to complete a liquid crystal display element. According to the above-described method for manufacturing a liquid crystal display element, a liquid crystal display element having an extremely fine circuit pattern can be obtained with high throughput.

1 is a perspective view schematically showing an overall configuration of an exposure apparatus according to an embodiment of the present invention. FIG. 6 is a diagram for explaining a relationship between a pattern formed on a mask and a pattern image formed on a plate in an enlargement multi-scanning exposure apparatus, where (a) shows a pattern formed on the mask; ) Shows a pattern image formed on the plate. FIGS. 4A and 4B are diagrams for explaining focus adjustment of each projection optical unit with respect to the deflection of a mask in a multi-scanning exposure apparatus, where FIG. 5A shows a state before focus adjustment, and FIG. 5B shows a state after focus adjustment. Yes. It is a figure explaining a mode that the position shift of an image plane arises between adjacent projection optical units even if focus adjustment is performed in an enlargement system multi-scanning type exposure apparatus. (A) is sectional drawing of the mask used illustratively for description of the basic principle of this invention, (b) is a figure which shows the light transmittance distribution of the mask of (a). It is a figure which shows the light intensity distribution of the aerial image formed via a projection optical unit when the mask of FIG. 5 is used. It is a figure which shows the change of the line width of the space pattern image in each defocus position, Comprising: The relationship between the line width of a space image and a defocus amount is shown. It is a figure which shows the relationship between the line width correction value of a mask pattern required in order to obtain a desired line width, and defocus amount. It is a figure which shows the relationship between the relative value of the dose amount of an exposure visual field required in order to obtain a desired line width, and defocus amount. It is a flowchart which shows each process of the exposure method to which the 1st method of this invention is applied. It is a figure which shows schematically the principal part structure of the exposure apparatus to which the 2nd method of this invention is applied. (A) is a transmittance distribution to be given to the density filter arranged in the optical path of the projection optical units PL5 and PL7 in FIG. 4, and (b) is a density arranged in the optical path of the projection optical unit PL6 in FIG. The transmittance distribution to be applied to the filter is shown. It is a figure which shows schematically the modification of the principal part structure of the exposure apparatus to which the 2nd method of this invention is applied. It is a figure which shows a mode that the line | wire width of a mask pattern is correct | amended discretely. It is a flowchart of the method at the time of obtaining the semiconductor device as a microdevice. It is a flowchart of the method at the time of obtaining the liquid crystal display element as a microdevice.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Elliptical mirror 3 Reflective mirror 4 Relay lens system 5 Fiber box 6 Fly eye integrator 7b Condenser lens system 11 Density filter M Mask PA Pattern area | region PL1-PL11 Projection optical unit P Plate

Claims (20)

In a manufacturing method of a mask used in an exposure apparatus that forms an overlapped exposure region by overlappingly exposing a part of an exposure field of a plurality of projection optical units on a substrate,
Obtaining information on a line width correction value of a pattern in the plurality of pattern areas on the mask that contributes to the formation of the overlapping exposure area;
And a step of forming a pattern on the mask based on the information of the line width correction value. The step of obtaining information related to the line width correction value of the pattern contributes to the formation of the overlapped exposure region so that the line widths of the pattern images in the plurality of pattern regions on the mask formed in the overlapped exposure region are equal. The method for manufacturing a mask according to claim 1, wherein information relating to a line width correction value of a pattern in the plurality of pattern regions on the mask to be obtained is obtained. In the step of obtaining information on the line width correction value of the pattern, the information on the mask that contributes to the formation of the overlapped exposure region based on the information on the shape of the pattern to be formed on the mask and the information on the deflection of the mask. The method for manufacturing a mask according to claim 1, wherein information relating to a line width correction value of a pattern in a plurality of pattern regions is obtained. The step of obtaining information relating to the line width correction value of the pattern includes the step of obtaining a pattern image formed via the projection optical unit based on information relating to the shape of the pattern to be formed on the mask and information relating to the deflection of the mask. Corresponding to the overlapping exposure region from the step of determining the relationship between the line width and the defocus amount of the pattern image from the imaging surface of the projection optical unit, and the relationship between the line width of the pattern image and the defocus amount The method for manufacturing a mask according to claim 1, further comprising a step of obtaining information on a line width correction value of a mask pattern to be masked. The step of obtaining information relating to the line width correction value of the pattern includes the step of determining the projection optical unit based on information relating to the shape of the pattern to be formed on the mask, information relating to deflection of the mask, and optical characteristics of the projection optical unit. By performing an aerial image simulation for calculating the line width of the spatial pattern image formed through the above, the line width of the spatial pattern image and the defocus amount of the spatial pattern image from the imaging plane of the projection optical unit A step of obtaining a relationship; and a step of obtaining information on a line width correction value of a pattern of a mask corresponding to the overlapped exposure region from a relationship between a line width of the spatial pattern image and the defocus amount. The manufacturing method of the mask of Claim 1 or 2. The step of obtaining information on the line width correction value of the pattern is based on the information on the shape of the pattern to be formed on the mask, the information on the deflection of the mask, the optical characteristics of the projection optical unit, and the characteristics of the resist. By performing a resist simulation for calculating the line width of the pattern image formed on the resist via the projection optical unit, the line width of the pattern image and the pattern on the resist from the imaging plane of the projection optical unit Obtaining a relationship between the defocus amount of the image and obtaining information regarding a line width correction value of the pattern of the mask corresponding to the overlapping exposure region from the relationship between the line width of the pattern image and the defocus amount. The method for manufacturing a mask according to claim 1, further comprising: The step of obtaining information regarding the line width correction value of the pattern includes measuring the line width of the pattern image printed on the resist via the projection optical unit, thereby determining the line width of the pattern image and the projection optical unit. A step of obtaining a relationship between the defocus amount of the pattern image on the resist from the imaging plane and a line of the mask pattern corresponding to the overlapped exposure region from the relationship between the line width of the pattern image and the defocus amount The method for manufacturing a mask according to claim 1, further comprising a step of obtaining information on the width correction value. In the mask manufacturing method,
Determining the deflection of the mask;
Obtaining information relating to a line width correction value of the mask pattern in accordance with the obtained mask deflection;
And a step of forming a pattern on the mask based on the information of the line width correction value. In an exposure method for projecting and exposing a pattern of the mask onto the substrate while relatively moving the mask and the substrate with respect to a plurality of projection optical units,
A mask manufacturing process for manufacturing the mask by the manufacturing method according to any one of claims 1 to 7,
A mask setting step for setting the mask manufactured in the mask manufacturing step with respect to the plurality of projection optical units;
And an exposure step of exposing the substrate with the mask pattern set in the mask setting step. A first projection optical unit for forming an image of a first pattern on the mask; and a second projection optical unit for forming an image of a second pattern on the mask. The mask for the first and second projection optical units. And an exposure apparatus that exposes the substrate by partially overlapping the first pattern image and the second pattern image while relatively moving the substrate,
An exposure apparatus comprising: a control device that controls at least one light intensity distribution of an exposure field of the first projection optical unit and an exposure field of the second projection optical unit according to the deflection of the mask. 11. The exposure apparatus according to claim 10, wherein the control apparatus controls a light intensity distribution of illumination light that illuminates at least one of the first and second patterns. The control device includes: a first light intensity distribution adjusting member that controls a light intensity distribution of illumination light that illuminates the first pattern according to the bending of the first pattern; and the first light intensity distribution adjusting member according to the bending of the second pattern. The exposure apparatus according to claim 11, further comprising a second light intensity distribution adjusting member that controls illumination light that illuminates the two patterns. A first projection optical unit for forming an image of a first pattern on the mask; and a second projection optical unit for forming an image of a second pattern on the mask. The mask for the first and second projection optical units. And an exposure apparatus that exposes the substrate by partially overlapping the first pattern image and the second pattern image while relatively moving the substrate,
The first projection is performed such that the line width of the first pattern image and the line width of the second pattern image are equal in an overlapping exposure region on the substrate where the image of the first pattern and the second pattern image overlap. An exposure apparatus comprising: a control device that controls at least one light intensity distribution of an exposure field of the optical unit and an exposure field of the second projection optical unit. The exposure apparatus according to claim 13, wherein the control apparatus controls a light intensity distribution of illumination light that illuminates at least one of the first and second patterns. The control device includes: a first light intensity distribution adjusting member that controls a light intensity distribution of illumination light that illuminates the first pattern; and a second light intensity distribution adjusting member that controls the illumination light that illuminates the second pattern; The exposure apparatus according to claim 14, comprising: 16. The exposure apparatus according to claim 12, wherein the first light intensity distribution adjusting member and the second light intensity distribution adjusting member include a density filter. The control device includes an overlapping area within an exposure field of the first projection optical unit that contributes to formation of an overlapping exposure area on the substrate, and the second projection optical unit that contributes to formation of an overlapping exposure area on the substrate. The exposure apparatus according to any one of claims 10 to 16, wherein the light intensity distribution of at least one of the overlapping area in the exposure field of the first and second exposure fields is controlled. 18. The exposure apparatus according to claim 10, wherein the first and second projection optical units have a magnification larger than an equal magnification. An exposure step of exposing the first and second patterns to the substrate using the exposure apparatus according to any one of claims 10 to 18.
And a development step of developing the substrate that has undergone the exposure step. In a method of manufacturing an electronic device using an exposure apparatus that forms an overlapping exposure region by overlappingly exposing a part of an exposure field of a plurality of projection optical units on a substrate,
Setting a correction mask in which the line width of the pattern in the plurality of pattern areas on the mask contributing to the formation of the overlapping exposure area is corrected with respect to a design value on the object plane of the plurality of projection optical units;
Controlling the light intensity distribution in at least one exposure field of the plurality of projection optical units so that line widths of pattern images in the plurality of pattern regions are equal;
And a step of exposing the substrate with a pattern of the correction mask.

Images