JP5055649B2 - Projection optical apparatus, exposure apparatus, device manufacturing method, image plane information detection apparatus, and projection optical system adjustment method - Google Patents

Description

  The present invention relates to a projection optical apparatus, an exposure apparatus, a device manufacturing method, an image plane information detection apparatus, and a projection optical system adjustment method. More specifically, the present invention relates to a multi-scanning exposure apparatus that projects and exposes a mask pattern onto a photosensitive substrate while relatively moving the mask and the photosensitive substrate with respect to a plurality of projection optical units.

  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 cost increases due to the increase in size. Therefore, in order to avoid enlarging the mask, an enlargement system multi-scanning exposure apparatus using a projection optical unit having an enlargement magnification has been devised. In the magnifying system multi-scanning type exposure apparatus, the optical energy density (unit area) irradiated to the optical member arranged on the mask side is larger than that of the unity-magnification multi-scanning type exposure apparatus that uses a projection optical unit of the same magnification. Per incident light irradiation energy), and the influence of light irradiation accompanying exposure on the imaging performance of the projection optical unit also increases.

  Further, in the magnifying system multi-scanning exposure apparatus, as in the case of the unit magnification system, the optical characteristics are strictly different for each projection optical unit due to, for example, a manufacturing error, and environmental changes such as temperature are also different for each projection optical unit. Different. In other words, in the multi-scanning exposure apparatus, the change in the imaging performance tends to be different for each projection optical unit. In particular, in the magnifying system multi-scanning exposure apparatus, the imaging performance of the projection optical unit changes due to light irradiation. It tends to be relatively large.

  The present invention has been made in view of the above-described problems, and individually detects information relating to changes in the imaging performance of a plurality of projection optical units having a magnification, and performs good projection using these projection optical units. An object of the present invention is to provide a multi-scanning exposure apparatus capable of performing exposure. Further, the present invention provides a device manufacturing method capable of manufacturing a good device with a large area by using a multi-scanning type exposure apparatus that performs good projection exposure using a plurality of projection optical units having a magnification. The purpose is to provide.

In order to solve the above-described problem, according to a first aspect of the present invention, there is provided a projection optical apparatus that forms an enlarged image of a first object disposed on a first surface on a second object disposed on a second surface. And
A projection optical unit having a plurality of magnifications arranged along a predetermined direction;
Image plane information detecting means for detecting information related to the image of the first object formed in the vicinity of the projection field of the projection optical unit via at least one of the plurality of projection optical units. ,
The image plane information detecting means detects image shift information related to displacement of the image of the first object in the second plane based on light reflected by the first plane through the projection optical unit. There is provided a projection optical device characterized by having an information detecting means.

  According to a second aspect of the present invention, there is provided an exposure apparatus comprising the projection optical apparatus according to the first aspect, wherein a pattern disposed on the first surface is projected and exposed onto a substrate disposed on the second surface. To do.

In the third aspect of the present invention, in an exposure apparatus for projecting and exposing a pattern arranged on the first surface to a substrate arranged on the second surface via a projection optical system having an enlargement magnification,
Image plane information detecting means for detecting information on the image of the pattern formed in the vicinity of the projection field of the projection optical system;
The image plane information detection means detects image shift information related to the displacement of the image of the pattern in the second plane based on the light reflected by the first plane through the projection optical system. There is provided an exposure apparatus having means.

In the fourth embodiment of the present invention, an exposure step of exposing the substrate to the pattern using the exposure apparatus of the second embodiment or the third embodiment;
And a developing process for developing the substrate that has undergone the exposure process.

In the fifth embodiment of the present invention, the enlarged image of the first object arranged on the first surface is formed in the vicinity of the projection field via the projection optical system that forms the second object arranged on the second surface. An image plane information detection device for detecting information related to an image of a first object,
Image shift information detecting means for detecting image shift information relating to displacement in the second surface of the image of the first object based on light reflected by the first surface through the projection optical system. An image plane information detecting device is provided.

According to a sixth aspect of the present invention, there is provided an adjustment method for adjusting the projection optical system using the image plane information detecting device according to the fifth aspect,
An adjustment method including an image shift adjustment step of adjusting a displacement of the image of the first object in the second plane is provided.

  In the magnifying system multi-scanning type exposure apparatus of the present invention, information on the mask pattern image formed in the vicinity of the projection field for each projection optical unit, that is, image shift information on the displacement of the mask pattern image on the plate and the mask pattern image The defocus information related to the defocus on the plate P is detected. As a result, by adjusting the shift and defocus of the image based on the image plane information, the imaging performance of the projection optical unit that easily changes due to light irradiation or the like can be kept good.

  In other words, the exposure apparatus of the present invention can individually detect information related to changes in the imaging performance of a plurality of projection optical units having a magnification, and perform excellent projection exposure using these projection optical units. Moreover, a high-precision liquid crystal display element, for example, can be manufactured as a good device with a large area by good projection exposure using the exposure apparatus configured according to the present 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 in FIG. 1) MS. 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 side light guide surface of the fiber box 5 is positioned. The light beam incident on the light guide of the fiber box 5 propagates through the inside thereof and then exits 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. In the magnifying multi-scanning exposure apparatus of the present embodiment, the number of projection optical units is not limited to 11, but may be 2 or more.

  A divergent light beam emitted from one typical emission 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 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 are also superimposed on the mask M via the collimating lens 7a, the fly-eye integrator 6, the aperture stop, and the condenser lens system 7b. Illuminate. In other words, the illumination system illuminates a plurality (11 in total in FIG. 1) of predetermined shapes arranged in the Y direction on the mask M. In this embodiment, as will be described later, a trapezoidal illumination area (an illumination field) is formed.

  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 that has passed through each of the trapezoidal illumination areas on the mask M is sent from a plurality of projection optical units PL1 to PL11 (a total of 11 in FIG. 1) 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. In the present embodiment, as will be described later with reference to FIG. 2, a one-time imaging type catadioptric optical system having an enlargement magnification is used as an example of each projection optical unit.

  Light through a projection optical system composed of a plurality of projection optical units PL1 to PL11 forms a mask pattern image on a plate P supported in parallel with the XY plane on a plate stage (not shown in FIG. 1) PS. To do. As described above, since each of the projection optical units PL1 to PL11 is configured as an enlargement system, a plurality of trapezoidal stationary elements arranged in the Y direction so as to correspond to each illumination area on the plate P that is a photosensitive substrate. An enlarged image of the mask pattern is formed in the exposure area.

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

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

  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 PS 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, the projection optical system composed of a plurality of projection optical units PL1 to PL11 is operated by the scanning drive system on the mask stage MS side and the scanning drive system on the plate stage PS side. By moving the mask M and the plate P along the X direction, the entire pattern area on the mask M is transferred (scanned exposure) to the entire exposure area on the plate P.

  FIG. 2 is a diagram schematically showing the configuration of each projection optical unit in the present embodiment. In the projection optical unit of this embodiment (typically, the projection optical unit PL1 or the like), as shown in FIG. 2, the light transmitted through the mask M supported in parallel with the XY plane on the mask stage MS is in the Z direction. Is incident on the first lens group G1 via the image shift correction member H1 and the defocus correction member H2. The configurations of the image shift correction member H1 and the defocus correction member H2 will be described later.

  The light incident on the first lens group G1 enters the concave reflecting mirror CM via the second lens group G2 along the optical path extending in the Z direction, and after being reflected by the concave reflecting mirror CM, the second lens group G2. Through the first plane reflecting mirror PM1. The light reflected in the X direction by the first plane reflecting mirror PM1 is deflected in the Z direction by the second plane reflecting mirror PM2, and then reaches the plate P via the third lens group G3. Thus, on the plate P supported in parallel with the XY plane on the plate stage PS, an inverted image that is an enlarged image of the pattern of the mask M and is inverted with respect to the Y direction is formed. Hereinafter, it is assumed that the projection magnification of the projection optical unit of the present embodiment is 2.5 times.

  The image shift correction member H1 includes, for example, a pair of parallel flat plates (only one parallel flat plate is shown in FIG. 2), and is set so that each optical plane is parallel to the XY plane in the reference state. Of the pair of parallel flat plates, one parallel flat plate is configured to be rotatable about the X axis, and the other parallel flat plate is configured to be rotatable about the Y axis. Accordingly, the position of the mask pattern image formed on the plate P via the projection optical unit moves in the Y direction (image shift) by the rotation of one parallel plane plate around the X axis.

  Similarly, rotation of the other plane-parallel plate around the Y-axis moves (image shift) the formation position of the mask pattern image formed on the plate P via the projection optical unit. Thus, in the image shift correction member H1, the formation position of the mask pattern image formed on the plate P by the combination of the rotation of one parallel plane plate around the X axis and the rotation of the other parallel plane plate around the Y axis. Can be moved two-dimensionally in the XY plane, that is, displacement (that is, displacement from the desired image formation position) of the mask pattern image on the plate P can be corrected (adjusted).

  For example, the defocus correction member H2 includes a pair of declination prisms having wedge-shaped cross-sectional shapes that are complementary to each other in the XZ plane, and is set to be in the form of a parallel plane plate as a whole in its reference state. Of the pair of declination prisms, one declination prism is configured to reciprocate along the X direction. Accordingly, when one of the declination prisms is reciprocated along the X direction, the optical path length between the mask M and the first lens group G1 is changed, and thus formed on the plate P via the projection optical unit. The formation position of the mask pattern image moves in the Z direction.

  Thus, the defocus correction member H2 adjusts the distance between the object image points of the projection optical unit, that is, corrects (adjusts) the defocus on the plate P of the mask pattern image by moving the one declination prism in the X direction. )can do. For a more detailed configuration and operation of the image shift correction member H1, Patent Document 1 and the like can be referred to. Japanese Patent Laid-Open No. 2003-309053 and the like can be referred to for a more detailed configuration and operation of the defocus correction member H2.

  FIG. 3 is a diagram illustrating the positional relationship between the pattern area on the mask and the trapezoidal illumination area. In FIG. 3, in order to facilitate understanding of the description, five pattern areas 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 are formed in the pattern areas PAa to PAe, respectively. In this case, the illumination system forms five trapezoidal illumination areas (areas corresponding to the projection field on the object side of the five projection optical units) ILa to ILe arranged in the Y direction on the mask M.

  Here, the lengths of the bottom sides of the illumination areas ILa to ILe correspond to the widths (dimensions in the Y direction) of the pattern areas PAa to PAe. In the central three pattern areas PAb to PAd, the central area extending in the X direction corresponding to the upper side of the illumination areas ILb to ILd corresponds to the area where the overlapping exposure is not performed, and extends in the X direction with hatching on both sides thereof. A region (a region corresponding to the oblique sides of the illumination regions ILb to ILd) corresponds to a region subjected to overlapping exposure. In the pattern areas PAa and PAe at both ends, only the outer hatched area corresponds to the area that is overexposed, and the other areas correspond to areas that are not overexposed.

  FIG. 4 is a diagram for explaining the positional relationship between the mask pattern image on the plate and the trapezoidal static exposure region. On the plate P, as shown in FIG. 4, five trapezoidal stationary exposure regions (in the Y direction) aligned in the Y direction so as to optically correspond to the five trapezoidal illumination regions ILa to ILe on the mask M. Regions ERa to ERe corresponding to the projection field on the image side of the five projection optical units are formed. On the plate P, enlarged pattern images PIa to PIe that are inverted with respect to the Y direction of the patterns PTa to PTe on the mask M are formed.

  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.

  As described above, in FIG. 4, the hatched area extending in the X direction including the overlapping exposure areas Lab to Lde, that is, the area extending in the X direction corresponding to the hypotenuse of the stationary exposure areas ERa to ERe is adjacent to the Y direction. This is an overlapping exposure region where a part of two matching mask patterns are exposed in an overlapping manner. On the other hand, an area extending in the X direction corresponding to the upper sides of the static exposure areas ERa to ERe, and an area extending in the X direction corresponding to the oblique sides outside the static exposure areas ERa and ERe at both ends are mask patterns. Is an exposure region that is not exposed in an overlapping manner.

  In an equal magnification multi-scanning type exposure apparatus, a projection optical unit that forms an equal magnification erect image by twice imaging is often adopted. However, in an enlargement system multi-scanning type exposure apparatus, in order to avoid an increase in the size of the projection optical unit, it is desirable to employ, for example, a one-time imaging type projection optical unit as shown in FIG. In this case, even if the projection magnification of the projection optical unit is set to 2.5, for example, the configuration of the once-imaging type projection optical unit becomes relatively complicated.

  Further, in the magnifying system multi-scanning type exposure apparatus, when the projection magnification of the projection optical unit is 2.5 times, the illuminance on the mask side is 6.25 (= 2.5 × 2.5) of the illuminance on the plate side. Double. That is, when the brightness on the plate side is the same in the magnifying system and the equal magnification system, in the magnifying system multi-scanning exposure apparatus, the optical member arranged on the mask side is irradiated as compared with the equal magnification system. The light energy density (light irradiation energy per unit area) increases, and the influence of light irradiation accompanying exposure on the imaging performance of the projection optical unit increases.

  Further, in the magnifying system multi-scanning type exposure apparatus, similarly to the unit magnification system, the optical characteristics are strictly different for each projection optical unit due to, for example, a manufacturing error, and the environmental change such as temperature is also different for each projection optical unit. In other words, in the multi-scanning exposure apparatus, the change in imaging performance varies from projection optical unit to projection optical unit. In particular, in the enlargement system multi-scanning exposure apparatus, the change in imaging performance of the projection optical unit due to light irradiation tends to be large. .

  Further, in the magnifying system multi-scanning type exposure apparatus, the depth of focus on the mask side is smaller than that in the same magnification system. Specifically, when the projection magnification of the projection optical unit is 2.5 times, the depth of focus on the mask side is 1 / 6.25 (≈1 / (2.5 × 2.5)) times that of the unit magnification system. Reduced. For this reason, in the magnifying system multi-scanning type exposure apparatus, the influence of the position and orientation of the mask on the image formation on the plate is increased.

  Therefore, the exposure apparatus of the present embodiment includes an image plane information detection apparatus that detects information related to a mask pattern image formed in the vicinity of the projection field (stationary exposure region) via the projection optical unit. The image plane information detection device is composed of a plurality of detection units having the same configuration. In the present embodiment, as an example, three detection units are arranged for one projection optical unit.

  FIG. 5 is a diagram schematically showing the configuration of each detection unit of the image plane information detection apparatus according to the present embodiment. As shown in FIG. 5, the detection unit of the present embodiment includes a light source 31 that supplies light having the same wavelength as exposure light, i.e., i-line light. The light emitted from the light source 31 becomes almost parallel light through the collimating lens 32 and illuminates the slit plate 33. As shown in FIG. 6, the slit plate 33 is provided with an elongated rectangular (slit-shaped) opening 33a having a longitudinal direction in a direction inclined, for example, 5 degrees with respect to the Z direction. The opening 33a is disposed at a position optically conjugate with the image plane of the projection optical unit (and thus the exposure surface of the plate P disposed at a desired position).

  The light diffracted by the opening 33 a of the slit plate 33 is incident on, for example, a prism type beam splitter 35 via the relay lens 34. The light reflected by the beam splitter 35 enters the reference sensor 43 and forms a slit image of the opening 33a. The light that has passed through the beam splitter 35 passes through, for example, a prism type beam splitter 36, and then forms a slit image of the opening 33a at a position indicated by reference numeral 37. The light from the slit image of the opening 33a is incident on the mirror 38 disposed in the vicinity of the projection field of the projection optical unit as shown in FIG.

  The light reflected by the mirror 38 forms a slit image of the opening 33a on or near the pattern surface of the mask M through the projection optical unit. The light reflected by the pattern surface of the mask M enters the mirror 38 via the projection optical unit. The light reflected by the mirror 38 is incident on the beam splitter 36 after forming a slit image of the opening 33a at or near the image position 37. The light reflected by the beam splitter 36 enters the image shift sensor 41 through the lens 40. The light transmitted through the beam splitter 36 is reflected by the beam splitter 35 and enters the focal position sensor 42 via the pupil half-hidden light shielding plate 44 and the lens 39. The pupil half-hidden light-shielding plate 44 is disposed on a pupil plane optically conjugate with the aperture stop of the projection optical unit, and shields one area divided by a straight line on the pupil plane that intersects the optical axis.

  The light beam incident on the focal position sensor 42 is only the light beam on the other side of the diffraction order because the light beam on one side of the diffraction order is shielded by the pupil semi-hidden light-shielding plate 44. That is, only the light beam from the half aperture is incident on the focal position sensor 42. The slit image of the opening 33a is, for example, 5 μm × 200 μm at the image position 37, and is, for example, 5 with respect to the Y direction (scanning orthogonal direction) when projected onto the pattern surface of the mask M as described later with reference to FIG. Is tilted. With this configuration, it is possible to reduce changes in the image shape on the sensor due to the influence of a mask pattern composed of a large number of line portions that are elongated in the vertical and horizontal directions along the X and Y directions.

  In the present embodiment, the magnification from the opening 33a of the slit plate 33 to the image position 37 is 1/9, the magnification from the image position 37 to the image shift sensor 41 is 20, and the magnification from the image position 37 to the focus position sensor. The magnification up to 42 is 9 times. As described above, the projection magnification of the projection optical unit, that is, the magnification from the mask M to the plate P is 2.5 times. Of the detection unit shown in FIG. 5, the part excluding the mirror 38 constitutes a unit main body 30.

  The relay lens 34, the beam splitters 35 and 36, and the mirror 38 guide the detection light from the opening 33a disposed at a position optically conjugate with the imaging plane of the projection optical unit from the vicinity of the projection field to the projection optical unit. A light guide system is configured. The light guide system (34, 35, 36, 38), the mirror 38, the beam splitter 36, the lens 40, and the image shift sensor 41, as will be described later with reference to FIG. Based on the light reflected by the surface, an image shift information detection unit is configured to detect image shift information related to displacement (positional deviation from the desired image formation position) of the pattern image of the mask M on the plate P. That is, the mirror 38, the beam splitter 36, the lens 40, and the image shift sensor 41 constitute a first detection system that detects image shift information based on the detection light that reciprocates along the optical path of the projection optical unit. In this embodiment, since the image shift information is detected based on the detection light reciprocating along the optical path of the projection optical unit, not only the pattern image displacement caused by the displacement of the mask M but also the pattern image displacement caused by the projection optical unit. That is, it is possible to detect the state of pattern image displacement that appears during actual exposure.

  As will be described later with reference to FIG. 9, the light guide system (34, 35, 36, 38), the mirror 38, the beam splitters 36, 35, the pupil half-hidden light-shielding plate 44, the lens 39, and the focus position sensor 42 are provided. A defocus information detection unit configured to detect defocus information related to defocus on the plate P of the pattern image of the mask M based on the light reflected by the pattern surface of the mask M through the projection optical unit. . In other words, the mirror 38, the beam splitters 36 and 35, the pupil half-hidden light-shielding plate 44, the lens 39, and the focal position sensor 42 are a second detection system that detects defocus information based on detection light reciprocating along the optical path of the projection optical unit. Is configured. As described above, in the present embodiment, since the information related to the defocusing of the pattern image is detected based on the detection light reciprocating along the optical path of the projection optical unit, only the defocusing of the pattern image due to the displacement of the mask M can be performed. First, it is possible to detect the defocus of the pattern image caused by the projection optical unit, that is, the defocus state of the pattern image that appears during actual exposure.

  Referring to FIG. 7, the mirrors 38a to 38c of the three detection units provided for each projection optical unit are disposed in the vicinity of the projection field of the projection optical unit, that is, the static exposure region ER. More specifically, the mirror 38a of the first detection unit and the mirror 38b of the second detection unit are arranged between the rear group G3b of the third lens group G3 of the projection optical unit and the plate P as shown in FIG. 7 and disposed in the vicinity of the overlapping field of view corresponding to the overlapping exposure region (region extending in the X direction corresponding to the hypotenuse of the trapezoid) in the static exposure region ER as shown in FIG. Has been.

  The mirror 38c of the third detection unit is disposed in the optical path between the rear group G3b of the third lens group G3 of the projection optical unit and the plate P, as shown in FIG. 7B, and FIG. As shown in FIG. 3, the first exposure unit mirror 38a and the second detection unit mirror 38b are disposed in the vicinity of the center in the Y direction of the static exposure region ER. Various modifications are possible for the number of detection units 30 provided for each projection optical unit, the arrangement of the mirrors 38, and the like.

  When the three detection units are arranged as shown in FIG. 7, three slit images 33aa, 33ab, 33ac of the opening 33a are formed on the pattern surface of the mask M as shown in FIG. More specifically, the three slit images 33aa, 33ab, 33ac are formed in the vicinity of the trapezoidal illumination area IL on the mask M and inclined by 5 degrees with respect to the Y direction. The formation positions of the three slit images 33aa, 33ab, 33ac with respect to the illumination area IL (positions corresponding to the three detection points on the mask M) are optically arranged in the arrangement of the three mirrors 38a, 38b, 38c with respect to the static exposure area ER. It corresponds to.

  Hereinafter, the principle of detecting defocus information related to defocus on the plate P of the mask pattern image in the focus position sensor 42 will be described with reference to FIG. In FIG. 9, in order to facilitate understanding of the explanation, the mirror 38 and the beam splitters 36 and 35 are omitted, and the optical path from the mask M to the focal position sensor 42 is developed linearly. The projection optical unit is represented by a single lens PLa. In FIG. 9, a broken line 51 indicates an optical path in a focus state where the pattern surface of the mask M (shown by a broken line in the drawing) is located at a position optically conjugate with the focus position sensor 42. A solid line 52 indicates an optical path in a defocus state in which the pattern surface of the mask M (shown by a solid line in the drawing) is displaced by ΔZ in the Z direction from a position optically conjugate with the focus position sensor 42.

  The focus position sensor 42 is initially positioned at a position optically conjugate with the pattern surface of the mask M when the pattern image is formed on the plate P in the best focus state. Therefore, when the pattern surface of the mask M is shifted in the Z direction by ΔZ from the position optically conjugate with the focus position sensor 42 (and thus the position optically conjugate with the exposure region on the plate P), defocusing is performed. The light amount center of the light beam incident on the focal position sensor 42 moves in the lateral direction by ΔL.

The movement amount ΔL of the light amount center of the light beam in the focal position sensor 42 is incident on the mask M through the projection optical unit with a projection magnification of 22.5 (= 2.5 × 9) from the mask M to the focal position sensor 42. determined by the numerical aperture NA _M of the detection light beam. In this embodiment, as an example, the movement amount ΔL is designed to be expressed by the following equation (1).
ΔL = 0.17 × ΔZ × 22.5 (1)

  The movement amount ΔL of the light beam center of the light beam in the focal position sensor 42 is a positional deviation along the Z direction between the position where the pattern image of the mask M is formed in the best focus state via the projection optical unit and the exposure surface of the plate P. It is related to the quantity or defocus quantity. Therefore, detecting the movement amount ΔL of the center of the light amount of the light beam by the focal position sensor 42 is nothing but detecting defocus information related to defocusing of the pattern image of the mask M on the plate P.

  In the above description, in order to facilitate understanding of the principle, an example is shown in which defocus information generated due to a positional shift along the Z direction of the mask M is detected. However, the focus position sensor 42 is not limited to the positional deviation of the mask M, and the defocus information of the pattern image on the plate P generated for some reason, such as a change in the imaging performance of the projection optical unit due to light irradiation. Can be detected.

  As the focal position sensor 42, a line sensor composed of line-shaped unit elements having the same length as the longitudinal dimension of the slit image formed on the focal position sensor 42 by the detection light from the opening 33 a of the slit plate 33 is used. It is preferable to do. With this configuration, the longitudinal dimension of the opening 33a of the slit plate 33 can be designed to be large, and a sufficient amount of received light can be secured in the focal position sensor 42 to improve S / N.

  In the present embodiment, the defocus information of the mask pattern image on the plate P is detected as needed at three positions surrounding the projection visual field by the three defocus information detection units provided for each projection optical unit. Then, as necessary, each projection optical unit is appropriately optically adjusted by the action of the defocus correction member H2, and the defocus on the plate P of the pattern image of the mask M is adjusted. Detection of defocus information by the defocus information detection unit is possible if the mask M is on the mask stage MS.

  Therefore, if the defocus information is detected during the non-exposure operation time such as when the plate P is exchanged, the defocus on the plate P of the pattern image of the mask M can be adjusted without reducing the throughput. . In the enlargement-type multi-scanning exposure apparatus, as shown in FIG. 3, since the pattern to be subjected to overlap exposure is formed on the mask M at a relatively large interval along the Y direction, this interval is used. It is conceivable that the position of the mask M is different in the Z direction between two regions that are separated from each other. Therefore, as in this embodiment, for each projection optical unit, it is important to detect defocus information and adjust the defocus of the image at two positions in the vicinity of the overlap field corresponding to the overlap exposure region, As a result, good overlapping exposure can be performed. In the present embodiment, the number of defocus information detection units provided for each projection optical unit is not limited to three. However, when the detection points of the plurality of defocus information detection units are three or more, it is possible to obtain the surface on which the mask pattern image is formed.

  Next, the principle of detecting image shift information related to displacement of the mask pattern image on the plate P in the image shift sensor 41 will be described with reference to FIG. In FIG. 10, in order to facilitate understanding of the explanation, the mirror 38 and the beam splitter 36 are omitted, and the optical path from the mask M to the image shift sensor 41 is developed linearly, and the lens 40 and the image shift sensor 41 are also developed. The reference sensor 43 is virtually arranged at a position optically conjugate with the actual position of the reference sensor 43 in the optical path between the two. Further, among the optical members constituting the projection optical unit, only the lens group (one or a plurality of lenses) close to the mask M is represented by a single lens PLb, and the other optical members are not shown.

  In FIG. 10, for example, it is assumed that the lens group PLb close to the mask M is shifted from a predetermined position indicated by a broken line in the drawing to a position indicated by a solid line in the drawing. An optical path 53 indicated by a broken line in the figure is an optical path when the lens group PLb is at a predetermined position, and an optical path 54 indicated by a solid line in the figure is an optical path when the lens group PLb is at a shifted position. The image shift sensor 41 is arranged behind the position optically conjugate with the image plane of the projection optical unit (and thus the display position of the reference sensor 43) by ΔZs.

Therefore, the image position of the opening 33a formed in the reference sensor 43 disposed at a position optically conjugate with the image plane of the projection optical unit is not affected by the shift of the lens group PLb. The incident angle θ (not shown) of the light beam 55 passing through the light quantity centroid of the light beam reaching 41 changes under the influence of the shift of the lens group PLb. As a result, when the lens group PLb is shifted, the light amount center of the light beam reaching the image shift sensor 41 moves in the lateral direction by ΔXs. The incident angle θ of the light intensity barycentric ray 55 is approximated by the following equation (2) by the lateral shift amount ΔXs measured by the image shift sensor 41 and the defocus amount ΔZs of the image shift sensor 41.
θ = ΔXs / ΔZs (2)

  The detection of the movement amount ΔXs of the light beam center of the light beam in the image shift sensor 41 is to detect image shift information related to the displacement of the pattern image of the mask M on the plate P (the positional deviation from the desired image formation position). There is nothing else. In the above description, in order to facilitate understanding of the principle, an example in which image shift information generated due to the shift of the lens group PLb close to the mask M is detected is shown. However, the image shift sensor 41 is not limited to the shift of the lens group PLb, but on the plate P generated for some reason, such as a change in the imaging performance of the projection optical unit or a change in the posture of the mask M due to light irradiation. The image shift information of the pattern image can be detected.

  If the position of the opening 33a of the slit plate 33 does not change with time, the installation of the reference sensor 43 can be omitted. Actually, considering the case where the position of the opening 33a of the slit plate 33 varies with time, the influence of the position variation of the slit plate 33 is based on the difference between the output of the image shift sensor 41 and the output of the reference sensor 43. It is preferable to detect the image shift information without substantially receiving.

  In the present embodiment, the image shift information of the mask pattern image on the plate P is detected at any time at three positions surrounding the projection field by three image shift information detection units provided for each projection optical unit. Then, if necessary, each projection optical unit is appropriately optically adjusted by the action of the image shift correction member H1, and the shift of the pattern image of the mask M on the plate P is adjusted. Specifically, the difference amount between the output of the image shift sensor 41 and the output of the reference sensor 43 is measured in the initial state.

  Then, when the difference amount fluctuates and exceeds a specified value after a predetermined time has elapsed, the image is so adjusted that the difference amount between the output of the image shift sensor 41 and the output of the reference sensor 43 is substantially equal to the difference amount in the initial state. Each projection optical unit is optically adjusted by the action of the shift correction member H1. Image shift information can be detected by the image shift information detector if the mask M is on the mask stage MS. Therefore, if the image shift information is detected during the non-exposure operation time such as when the plate P is replaced, the shift of the pattern image of the mask M on the plate P can be adjusted without reducing the throughput.

  In the enlargement-type multi-scanning exposure apparatus, as shown in FIG. 3, since the pattern to be subjected to overlap exposure is formed on the mask M at a relatively large interval along the Y direction, this interval is used. It is conceivable that the posture of the mask M is different between two regions that are separated from each other. Therefore, as in this embodiment, for each projection optical unit, it is important to detect the image shift information and adjust the image shift at two positions near the overlap field corresponding to the overlap exposure region. Better overlapping exposure can be performed. In the present embodiment, the number of image shift information detection units provided for each projection optical unit is not limited to three.

  As described above, in the present embodiment, the information about the mask pattern image formed in the vicinity of the projection field for each projection optical unit, that is, the image shift information about the displacement of the mask pattern image on the plate and the plate P of the mask pattern image. Defocus information related to the above defocus is detected. Therefore, by adjusting the shift and defocus of the image based on the image plane information, the imaging performance of the projection optical unit that is likely to change due to light irradiation or the like can be kept good, and as a result Overlap exposure can be performed.

  In the above-described embodiment, the slit plate 33 disposed at a position optically conjugate with the imaging surface of the projection optical unit is provided with an elongated rectangular (slit) opening 33a. However, the present invention is not limited to the slit shape, and openings having various shapes such as a cross shape and a V shape can be used. For example, by using a cross-shaped opening, it is possible to detect a focus difference in two orthogonal directions on the plate. However, in this case, it is necessary to use a two-dimensional sensor as the focal position sensor.

  Also, various forms of the specific configuration of the opening are possible. For example, a hole having a predetermined shape formed in a light-shielding (light-reducing) member, a light transmitting portion formed by a light-shielding (light-reducing) member formed on a light-transmitting substrate, or a reflection having a predetermined shape The opening of the present embodiment can be realized by the reflecting portion formed by the conductive member.

  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. FIG. 11 shows an example of a technique for obtaining a semiconductor device as a micro device by forming a predetermined circuit pattern on a wafer or the like as a photosensitive substrate using the exposure apparatus of this embodiment shown in FIG. This will be described with reference to a flowchart.

  First, in step 301 of FIG. 11, 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. 12, in a pattern forming process 401, a so-called photolithography process is performed in which the exposure pattern of the present 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.

  In the above-described embodiment, an example in which the present invention is applied to an enlargement multi-scanning exposure apparatus is shown. However, the present invention is not limited to this, and a projection optical device that forms an enlarged image of the first object arranged on the first surface on the second object arranged on the second surface, or projection optics having an enlargement magnification Similarly, the present invention can be applied to an exposure apparatus that collectively projects and exposes a pattern arranged on the first surface to a substrate arranged on the second surface via a system. Further, the present invention is not limited to application to an exposure apparatus or a projection optical apparatus that includes a plurality of projection optical units, but can also be applied to an exposure apparatus that includes a single projection optical system having a magnification. . In this case, it is possible to reduce the influence of the position and posture of the mask on the image formation on the plate due to the small depth of focus on the mask side.

1 is a perspective view schematically showing an overall configuration of an exposure apparatus according to an embodiment of the present invention. It is a figure which shows schematically the structure of each projection optical unit in this embodiment. It is a figure explaining the positional relationship of the pattern area | region on a mask, and a trapezoid-shaped illumination area | region. It is a figure explaining the positional relationship of the mask pattern image on a plate, and the trapezoid-shaped static exposure area | region. It is a figure which shows schematically the structure of each detection unit of the image surface information detection apparatus concerning this embodiment. It is a figure which shows a mode that opening is provided in the slit board of FIG. It is a figure explaining the example of arrangement of three detection units provided for every projection optical unit. It is a figure which shows a mode that three opening images are formed in the vicinity of an illumination area in the pattern surface of a mask. It is a figure explaining the principle which detects the defocus information regarding the defocus on the plate of a mask pattern image in a focus position sensor. It is a figure explaining the principle which detects the image shift information regarding the displacement on the plate of a mask pattern image in an image shift sensor. 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 Reflecting mirror 4 Relay lens system 5 Fiber box 6 Fly eye integrator 7b Condenser lens system 30 Main body of detection unit 38 Mirror of detection unit 41 Image shift sensor 42 Focus position sensor M Mask MS Mask stages PL1-PL11 Projection optical unit P Plate PS Plate stage

Claims (24)

A projection optical device that forms an enlarged image of a first object disposed on a first surface on a second object disposed on a second surface,
A projection optical unit having a plurality of magnifications arranged along a predetermined direction;
And an image plane information detecting means for detecting information about an image of the at least one projection optical unit of the plurality of projection optical units,
The image plane information detection means is a position between the projection optical unit and the second surface for projection light from the projection optical unit to a region where the enlarged image is formed on the second surface. Based on the detection light that has passed through the projection optical unit after being incident on the projection optical unit from the detection light incident position that is the position outside the optical path and reflected by the first surface through the projection optical unit. And a projection optical apparatus comprising image shift information detecting means for detecting image shift information relating to a displacement of the image of the first object in the second plane.
The image shift information detecting means includes a light guide system that guides detection light from an opening disposed at a position optically conjugate with the second surface from the detection light incident position to the projection optical unit, and the projection optical unit. The projection optical apparatus according to claim 1, further comprising: a detection system that detects the image shift information based on the detection light that reciprocates along the optical path.
The image plane information detection unit detects defocus information related to defocus on the second surface of the image of the first object based on light reflected by the first surface through the projection optical unit. The projection optical apparatus according to claim 1, further comprising a focus information detection unit. 4. The projection optical apparatus according to claim 3, wherein the defocus information detection unit includes a second detection system that detects the defocus information based on the detection light that reciprocates along an optical path of the projection optical unit. . 5. The projection optical apparatus according to claim 3, wherein the defocus information detection unit projects detection light to a plurality of detection points on the first surface via the projection optical unit. 6. The image plane information detection unit projects detection light to a plurality of detection points on the first surface via the projection optical unit. Projection optical device. 2. The projection exposure of an image of the first object onto the second object while relatively moving the substrate along a scanning direction with respect to the enlarged images formed by the plurality of projection optical units. 7. The projection optical apparatus according to any one of items 6. The said image plane information detection means detects the information regarding the image of the said 1st object formed in the vicinity of the overlap visual field corresponding to the overlap exposure area | region among the said projection visual fields. Projection optical device. The projection optical apparatus according to claim 1, wherein the projection optical unit includes an image shift correction unit that corrects a displacement of the image of the first object in the second plane. . The projection optical unit according to any one of claims 3 to 9, wherein the projection optical unit includes a defocus correction unit that corrects defocus on the second surface of the image of the first object. apparatus. An exposure apparatus comprising the projection optical apparatus according to claim 1, wherein the exposure apparatus projects and exposes a pattern arranged on the first surface onto a substrate arranged on the second surface. In an exposure apparatus for projecting and exposing a pattern disposed on a first surface to a substrate disposed on a second surface via a projection optical system having an enlargement magnification,
Image plane information detecting means for detecting information relating to the image of the projection optical system;
The image plane information detection unit is an optical path of projection light that is a position between the projection optical system and the second surface and extends from the projection optical system to a region where an enlarged image on the second surface is formed. Based on the detection light that has entered the projection optical system from the detection light incident position that is an outer position of the projection light, and has been reflected by the first surface through the projection optical system and then passed through the projection optical system An exposure apparatus comprising image shift information detecting means for detecting image shift information relating to displacement of the pattern image in the second plane.
The image shift information detection means includes a light guide system that guides detection light from an opening disposed at a position optically conjugate with the second surface from the detection light incident position to the projection optical system, and the projection optical system. The exposure apparatus according to claim 12, further comprising: a detection system that detects the image shift information based on the detection light that reciprocates along the optical path.
The image plane information detection means detects defocus information related to defocus on the second surface of the image of the pattern based on light reflected by the first surface through the projection optical system. 14. The exposure apparatus according to claim 12, further comprising a detection unit. The exposure apparatus according to claim 14, wherein the defocus information detection unit includes a second detection system that detects the defocus information based on the detection light that reciprocates along an optical path of the projection optical system. The exposure apparatus according to claim 12, wherein the projection optical system includes an image shift correction unit that corrects a displacement of the image of the pattern in the second surface. The exposure apparatus according to claim 14, wherein the projection optical system includes a defocus correction unit that corrects defocus of the pattern image on the second surface. An exposure step of exposing the substrate to the pattern using the exposure apparatus according to claim 11;
And a developing step of developing the substrate that has undergone the exposure step. Information about the image of the first object formed in the vicinity of the projection field via the projection optical system that forms an enlarged image of the first object arranged on the first surface on the second object arranged on the second surface. An image plane information detection device for detecting,
Detection is a position between the projection optical system and the second surface, and a position outside the optical path of the projection light from the projection optical system to a region where the magnified image is formed on the second surface. An image of the first object is incident on the projection optical system from a light incident position and is reflected by the first surface after passing through the projection optical system and then passing through the projection optical system. An image plane information detecting device comprising image shift information detecting means for detecting image shift information relating to displacement in the second plane.
The image shift information detection means includes a light guide system that guides detection light from an opening disposed at a position optically conjugate with the second surface from the detection light incident position to the projection optical system, and the projection optical system. The image plane information detection apparatus according to claim 19, further comprising: a detection system that detects the image shift information based on the detection light that reciprocates along an optical path of the image. Defocus information detection means for detecting defocus information related to defocus on the second surface of the image of the first object based on light reflected by the first surface through the projection optical system. 21. The image plane information detection apparatus according to claim 19, wherein the image plane information detection apparatus is characterized. The image plane information according to claim 21, wherein the defocus information detection means includes a second detection system that detects the defocus information based on the detection light reciprocated along an optical path of the projection optical system. Detection device. An adjustment method for adjusting the projection optical system using the image plane information detection device according to any one of claims 19 to 22,
An adjustment method comprising an image shift adjustment step of adjusting a displacement of the image of the first object in the second plane. The adjustment method according to claim 23, further comprising a defocus adjustment step of adjusting defocus on the second surface of the image of the first object.

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