JP2006134932A - Variable slit device, illumination optical device, aligner, and method of exposure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a uniform illuminance distribution in a surface to be illuminated. <P>SOLUTION: A variable slit device 100 which forms a slit-like illuminating area on a surface to be illuminated based on a luminous flux from a light source includes a first shield 10 having a plurality of blades 30 for specifying one long side L2 of the slit-like illuminating area, a second shield 20 for specifying the other long sides L1 of the slit-like illuminating region, and a driving mechanism 50 for driving the first shield 10 and changing the shape of the longitudinal direction of the illuminating light. The second shield 20 is formed in a curved state including the secondary or more components to correct the secondary or more components of the illuminating distribution unevenness in the surface to be illuminated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a variable slit apparatus, an illumination optical apparatus, an exposure apparatus, and an exposure method, and more particularly, to an exposure apparatus and method for manufacturing a microdevice such as a semiconductor element, an imaging element, a liquid crystal display element, and a thin film magnetic head in a lithography process. The present invention relates to an illumination optical apparatus suitable for an exposure apparatus and a variable slit apparatus suitable for the illumination optical apparatus.

  In a typical exposure apparatus of this type, a light beam emitted from a light source is used as a substantial surface light source composed of a large number of light sources via a fly-eye lens (or a micro fly-eye lens or the like) as an optical integrator. A secondary light source is formed. The luminous flux from the secondary light source is condensed by the condenser lens and illuminates the mask on which a predetermined pattern is formed in a superimposed manner. The light transmitted through the mask pattern forms an image on the wafer via the projection optical system. Thus, the mask pattern is projected and exposed (transferred) onto the wafer. The pattern formed on the mask is highly integrated, and it is essential to obtain a uniform illuminance distribution on the wafer in order to accurately transfer this fine pattern onto the wafer.

  However, due to, for example, a manufacturing error of an optical member constituting the illumination optical device, a quadratic component (a component defined according to a quadratic function of position coordinates), a quaternary component, or a higher component on the wafer. Including illumination distribution unevenness may occur.

  In this case, the phenomenon that the line width of the pattern actually formed on the wafer is substantially different from the desired line width due to the uneven illuminance distribution including the second and higher components, that is, the line width abnormality occurs. was there.

  Accordingly, a first object of the present invention is to obtain a uniform illuminance distribution on the irradiated surface by satisfactorily correcting the second or higher order component of the illuminance distribution unevenness on the irradiated surface. In addition, a second object of the present invention is to perform good exposure that does not substantially cause line width abnormality.

  In order to achieve the first object described above, a variable slit device according to the present invention is a variable slit device that forms a slit-shaped illumination area on an irradiated surface based on a light beam from a light source, wherein the slit A first light-shielding part having a plurality of blades for defining one long side of the illumination area, a second light-shielding part defining the other long side of the slit-shaped illumination area, and the first light-shielding part And a drive mechanism for changing the shape of the illumination light in the longitudinal direction. The second light-shielding portion is formed in a curved shape including a second-order or higher component in order to correct a second-order or higher component of the illuminance distribution unevenness on the irradiated surface. .

  In order to achieve the above first object, an illumination optical device according to the present invention is an illumination optical device that illuminates a surface to be irradiated based on a light beam from a light source, and includes the above variable slit device, An optical integrator disposed in an optical path between the light source and the irradiated surface. And the said variable slit apparatus correct | amends at least one part of the illumination intensity distribution nonuniformity in the said to-be-irradiated surface resulting from the said optical integrator, It is characterized by the above-mentioned.

  In order to achieve the second object, an exposure apparatus according to the present invention includes the illumination optical apparatus for illuminating a mask, and exposes a pattern of the mask onto a photosensitive substrate. Features.

  In order to achieve the second object, an exposure method according to the present invention illuminates a mask via the illumination optical device described above, and exposes a pattern formed on the mask onto a photosensitive substrate. It is characterized by that.

  In the variable slit device of the present invention, the high-order component of the illuminance distribution unevenness on the irradiated surface can be corrected by the action of the first light-shielding portion having a plurality of blades, and it is formed in a curved shape including secondary or higher-order components. Due to the action of the second light-shielding part, it is possible to correct a second-order or higher component of the illuminance distribution unevenness on the irradiated surface. Due to the action of the second light shielding part, the stroke of the drive mechanism that drives the first light shielding part having a plurality of blades can be shortened. That is, there is an advantage that the positioning accuracy of a plurality of blades by the driving mechanism can be improved compared to the case where the second light shielding portion is formed in a straight line and the stroke of the driving mechanism is lengthened. The illuminance distribution on the surface can be adjusted with high accuracy. Therefore, in the exposure apparatus and the exposure method using the illumination optical apparatus provided with the variable slit device of the present invention, it is possible to perform a good exposure without causing a line width abnormality substantially, and thus a good micro device. Can be manufactured.

Hereinafter, embodiments of the variable slit device of the present invention will be described with reference to the drawings. FIG. 1 is a view showing a variable slit device 100.
First, illumination light emitted from a light source (not shown) passes through a shaping optical system and is shaped into rectangular illumination light.

  And the variable slit apparatus 100 changes the width | variety in the longitudinal direction of the illumination light EL shaped in the rectangular shape, and forms the slit-shaped illumination light EL which has a desired slit width. The variable slit device 100 includes a first light shielding unit 10 that shields a part of the passing illumination light EL in order to define one long side L2 of the slit illumination light EL, and the other of the slit illumination light EL. In order to define the long side L1, the second light shielding unit 20 that shields a part of the passing illumination light EL and the actuator unit 50 that drives the first light shielding unit 10 are provided. That is, the variable slit device 100 arbitrarily shields both the long sides L1 and L2 in the longitudinal direction of the passing illumination light EL by driving the actuator unit 50, and the first light shielding unit 10 and the second light shielding unit 20. The width in the longitudinal direction of the illumination light EL passing through the space M is partially changed.

  Therefore, the first light-shielding part 10 and the second light-shielding part 20 form a slit-shaped illumination light EL having a slit width S that is partially changed. Note that both short sides of the illumination light EL are defined by two blades (not shown).

The slit width S direction of the illumination light EL is defined as the Y ₀ direction, and the longitudinal direction of the illumination light EL is defined as the X ₀ direction.
The first light shielding unit 10 has a plurality of blades 30, and the plurality of blades 30 are driven independently of each other. The plurality of blades 30 are arranged in a plane orthogonal to the optical axis of the illumination light EL, and are arranged in a comb-like shape without gaps in the plane.

Each blade 30 is formed in a long plate shape, and its longitudinal direction is arranged in parallel to the Y ₀ direction. Moreover, since each blade 30 is heated by the illumination light EL, it is formed of a heat-resistant material, for example, a metal such as stainless steel. Furthermore, a surface treatment is performed so that the blade 30 can slide while in contact with the adjacent blade 30.

Further, a linear edge portion is formed at one end portion in the longitudinal direction of each blade 30, and this edge portion defines one long side L2 of the slit-shaped illumination light EL. . The edge portion is formed in parallel with the _X0 direction. Each edge portion is formed to a thickness of about 10 μm. This is to accurately match the position in the optical axis direction (Z ₀ direction) where the slit-shaped illumination light EL is blocked.

The other end of each blade 30 in the longitudinal direction is connected to a linear actuator 70 described later via a rod 72. Accordingly, by moving each rod 72 by an arbitrary distance in the slit width S direction (Y ₀ direction) of the illumination light EL, each blade 30 moves in the Y ₀ direction, and one length of the illumination light EL is obtained. The side L2 is defined.

The second light-shielding portion 20 is constituted by a substantially long plate-like single blade 40, the blade 40 has its longitudinal direction is parallel to the X ₀ direction.
The blade 40 is made of the same material as the blade 30, and the edge portion on the side of the illumination light EL includes a function including a quadratic or higher order component (a quadratic function or a quadratic function of position coordinates, a higher order function higher than that, etc.). And a thickness of about 10 μm.

  The actuator unit (drive mechanism) 50 includes a plurality of linear actuators 70 and a rod 72 connected to each linear actuator 70. The linear actuator 70 can linearly move the rod 72 by an arbitrary distance in the axial direction, and for example, a voice coil motor or the like can be used.

The actuator unit 50 includes the same number of linear actuators 70 and rods (first push / pull members) 72 as the number of the blades 30. By driving each linear actuator 70, each blade 30 is moved in the Y ₀ direction via the rod 72. Move to.

Next, an embodiment in which the variable slit device 100 described above is applied to an illumination device and an exposure device will be described. FIG. 2 is a schematic diagram showing the exposure illumination system 121 and the exposure apparatus EX.
The exposure apparatus EX moves the reticle (mask) R and the wafer (substrate) P relatively synchronously in the one-dimensional direction while irradiating the reticle R with exposure illumination light (exposure light) EL. This is a so-called scanning stepper, which is a step-and-scan type scanning exposure apparatus that transfers a formed pattern (circuit pattern or the like) onto the wafer W via the projection optical system PL. In such an exposure apparatus EX, the pattern of the reticle R can be exposed in an area on the wafer W wider than the exposure field of the projection optical system PL.

  The exposure apparatus EX includes a light source 120, an exposure illumination system 121 that irradiates a reticle R with exposure illumination light EL from the light source 120, a reticle stage RS that holds the reticle R, and an exposure illumination light EL that is emitted from the reticle R. A projection optical system PL for irradiating W, a wafer stage WS for holding the wafer W, a main control system 220 for comprehensively controlling the operation of the exposure apparatus EX, and the like. The exposure apparatus EX is housed in a chamber (not shown) as a whole.

  In the XYZ orthogonal coordinate system, the X axis and the Y axis are set so as to be parallel to the wafer stage WS holding the wafer W, and the Z axis is set in a direction orthogonal to the wafer stage WS. Actually, in the XYZ orthogonal coordinate system in the figure, the XY plane is set to a plane parallel to the horizontal plane, and the Z axis is set to the vertical direction.

As the light source 120, vacuum ultraviolet rays having a wavelength of about 120 nm to about 190 nm, for example, ArF excimer laser (wavelength: 193 nm), fluorine (F ₂ ) laser (157 nm), krypton (Kr ₂ ) laser (146 nm), argon (Ar ₂ ) ) One that generates a laser (126 nm) or the like is used. The reason why vacuum ultraviolet rays are used as the illumination light EL for exposure is to cope with the fine line width of the pattern formed on the wafer W.

  In addition, the light source 120 is provided with a light source control device (not shown). This light source control device responds to an instruction from the main control system 220 and emits the oscillation center wavelength and the spectrum half of the exposure illumination light EL to be emitted. Performs control of value width, trigger control of pulse oscillation, etc.

The exposure illumination system (illumination device) 121 irradiates the exposure illumination light EL emitted from the light source 120 in a predetermined illumination area on the reticle R with a substantially uniform illuminance distribution.
Specifically, the exposure illumination light EL emitted from the light source 120 is deflected by the deflecting mirror 130 and enters a variable dimmer 131 as an optical attenuator. The variable dimmer 131 can adjust the dimming rate stepwise or continuously in order to control the exposure amount of the photoresist on the wafer. The exposure illumination light EL emitted from the variable dimmer 131 reaches the micro fly's eye lenses 136a and 136b through the diffractive optical element 132 and the zoom lens 134 provided on the turret 132 in this order.

  FIG. 3 is a perspective view schematically showing the configuration of the micro fly's eye lens of FIG. FIG. 4 is a diagram for explaining the operation of the micro fly's eye lens of FIG. Referring to FIG. 3, the micro fly's eye lens 136 includes a first fly eye member 136a disposed on the light source side and a second fly eye member 136b disposed on the mask side (irradiated surface side). . The first fly eye member 136a and the second fly eye member 136b have the same configuration as a whole, but the radii of curvature of the refracting surfaces, the material thereof, and the like do not necessarily match.

  More specifically, cylindrical lens groups 137a and 137b arranged along the X direction are respectively formed on the light source side surface of the first fly eye member 136a and the light source side surface of the second fly eye member 136b. Yes. That is, the cylindrical lens groups 137a and 137b formed on the light source side surface of the first fly eye member 136a and the light source side surface of the second fly eye member 136b have a pitch p1 along the X direction.

  On the other hand, cylindrical lenses arranged along the Y direction on the mask side (variable slit 100 side) surface of the first fly's eye member 136a and the mask side (variable slit 100 side) surface of the second fly's eye member 136b. Groups 138a and 138b are formed respectively. That is, the cylindrical lens groups 138a and 138b formed on the mask side surface of the first fly eye member 136a and the mask side surface of the second fly eye member 136b have a pitch p2 along the Y direction. In the present embodiment, the pitch p1 of the cylindrical lens groups 137a and 137b formed on the light source side surface is smaller than the pitch p2 of the cylindrical lens groups 138a and 138b formed on the mask side (variable slit 100 side) surface. Is set.

  Referring to FIG. 4A, when attention is paid to the refraction action in the X direction of the micro fly's eye lens 50 (that is, the refraction action in the XZ plane), the parallel light flux incident on the micro fly's eye lens 136 along the optical axis AX is as follows. The wavefront is divided at the pitch p1 along the X direction by the cylindrical lens group 137a formed on the light source side (left side in the drawing) of the first fly-eye member 136a. Then, the light beam incident on each cylindrical lens of the cylindrical lens group 137a is subjected to a condensing action on its refractive surface, and then corresponds to one of the cylindrical lens groups 137b formed on the light source side of the second fly's eye member 136b. The light is focused on the refracting surface of the cylindrical lens and focused on the rear focal plane 136c of the micro fly's eye lens 136.

  On the other hand, referring to FIG. 4B, focusing on the refraction action in the Y direction of the micro fly's eye lens 50 (that is, the refraction action in the YZ plane), the parallel light incident on the micro fly's eye lens 136 along the optical axis AX. The light beam is wavefront-divided at a pitch p2 along the Y direction by a cylindrical lens group 138a formed on the mask side (right side in the drawing) of the first fly-eye member 136a. Then, the light beam incident on each cylindrical lens of the cylindrical lens group 138a is focused on the refractive surface thereof, and then formed on the mask side (the variable slit 100 side) of the second fly's eye member 136b. The light is condensed on the refractive surface of the corresponding cylindrical lens 138b and condensed on the rear focal plane 136c of the micro fly's eye lens 136.

  Unlike the position of the entrance pupil plane in the X direction of the micro fly's eye lens 50 and the position of the entrance pupil plane in the Y direction, the entrance pupil plane in the X direction is located closer to the light source than the entrance pupil plane in the Y direction. Will do. As described above, the micro fly's eye lens 136 of the present embodiment is configured by the first fly eye member 136a and the second fly eye member 136b arranged at intervals along the optical axis AX. An optical function similar to that of a normal fly-eye lens configured by arranging a large number of lens elements having a size of p1 in the direction and a size of p2 in the Y direction vertically and horizontally is densely exhibited.

  In the present embodiment, the size and shape of the effective light source are set as desired by the operation of switching the diffractive optical element 132 on the turret 133 and the zooming operation by the zoom lens 134. This diffractive optical element forms an illuminance distribution in the far field, such as an annular shape, multipolar illuminance distribution such as 2-pole, 3-pole, 4-pole, 5-pole, 6-pole, and 8-pole. In cooperation with the above, an annular, multipolar or circular illuminance distribution is formed on the incident surface of the micro fly's eye lens 136. A plurality of types of diffractive optical elements 132 are provided on the turret 133. By switching the type of the diffractive optical elements 132, switching between a normal circular effective light source, an annular effective light source, and a multipolar effective light source is performed. Is possible. Further, the size of the effective light source can be changed by zooming of the zoom lens 134.

  The turret 133 is rotated by a driving device such as a motor, and any one of the diffractive optical elements 132 is selectively disposed on the optical path of the exposure illumination light EL, thereby forming the shape of the secondary light source on the pupil plane. The size is formed in a ring zone, a circle, or a multi-pole. As described above, the illumination condition of the reticle R can be changed by disposing any one of the diffractive optical elements 132 on the optical path of the exposure illumination light EL.

  Further, the illumination light EL for exposure emitted from the micro fly's eye lens 136 illuminates the variable slit 100 via the condenser lens group 140. The exposure illumination light EL emitted from the variable slit 100 passes through an illumination field stop imaging optical system (reticle blind imaging system) including deflection mirrors 142 and 145 and lens groups 143, 144, 146 and 147. Guided onto reticle R.

  As shown in FIG. 2, the variable slit device 100 is arranged at a position conjugate with the pattern of the reticle R (strictly, near the conjugate position), and changes the slit width S of the exposure illumination light EL. Let Further, when the slit width S of the variable slit device 100 is changed, the slit width S in the scanning direction (Y direction) of the exposure illumination light EL irradiated on the reticle R is changed.

As a result, an illumination area (exposure field) having the same shape as the opening of the variable slit device 100 is formed on the reticle R.
The reticle stage RS is provided immediately below the exposure illumination system 121 and includes a reticle holder or the like that holds the reticle R. The reticle holder (not shown) is supported by the reticle stage RS, has an opening corresponding to the pattern on the reticle R, and holds the reticle R pattern by vacuum suction with the pattern on the reticle R down. The reticle stage RS is one-dimensionally scanned and moved in the Y direction by a drive unit (not shown), and can be finely moved in the X direction and the rotation direction (θ direction around the Z axis). Accordingly, the reticle R can be positioned so that the center of the pattern area of the reticle R passes through the optical axis of the projection optical system PL.

Then, the position of reticle R in the Y direction is sequentially detected by laser interferometer 150 and output to main control system 220.
The projection optical system PL is provided immediately below the reticle stage RS, reduces the illumination light EL emitted through the reticle R by a predetermined projection magnification β (β is, for example, 1/4), and the pattern of the reticle R is reduced. An image is formed on a specific area on the wafer W.

  The wafer stage WS includes a wafer holder 180 or the like that holds the wafer W. Wafer holder 180 is supported by wafer stage WS and holds wafer W by vacuum suction. The wafer stage WS is formed by superposing a pair of blocks movable in directions orthogonal to each other on the surface plate 183, and can be moved in an XY plane by a drive unit (not shown).

Then, the position of the wafer stage WS in the X direction and the Y direction is sequentially detected by a laser interferometer 151 provided outside and is output to the main control system 220 (not shown).
At the end of the wafer stage WS on the −Y side, a Y moving mirror 152 made of a plane mirror is extended in the X direction. A measurement beam from a Y-axis laser interferometer 151 arranged substantially perpendicularly to the outside is projected onto the Y moving mirror 152, and the reflected light is received by the Y-axis laser interferometer 151. Is detected. Further, the X position of the wafer W is detected by an X-axis laser interferometer (not shown) with a substantially similar configuration.

  Then, by moving the wafer stage WS in the XY plane, an arbitrary shot area on the wafer W is positioned at the projection position (exposure position) of the pattern on the reticle R, and an image of the pattern on the reticle R is projected and transferred onto the wafer W. To do.

  A grazing incidence autofocus sensor 181 and an off-axis alignment sensor 182 for detecting the position (focus position) and tilt angle of the surface of the wafer W are provided above the wafer stage WS. .

The main control system (control device) 220 controls the exposure apparatus EX in an integrated manner, and includes a calculation unit 221 that performs various calculations and a storage unit 222 that records various types of information.
For example, the exposure operation for transferring the image of the pattern formed on the reticle R to the shot area on the wafer W is repeatedly performed by controlling the positions of the reticle stage RS and the wafer stage WS.

Further, the actuator unit 50 of the variable slit device 100 is instructed to control the shape of the light shielding unit 10 to make the integrated exposure amount uniform.
Subsequently, a method for performing an exposure process for transferring a pattern formed on the reticle R onto the wafer W using the variable slit device 100, the exposure illumination system 121, and the exposure apparatus EX having the above-described configuration will be described. To do.

  Reticle R and wafer W are placed on reticle stage RS and wafer stage WS, respectively, and reticle R is irradiated with exposure illumination light EL from exposure illumination system 121. The light from the illumination area on the reticle R is guided onto the wafer W via the projection optical system PL, and the pattern in the illumination area of the reticle R is projected on the wafer W after being reduced.

  Then, the reticle R and the wafer W are moved synchronously with each other in the direction of the slit width S of the exposure illumination light EL while being irradiated with the slit-shaped exposure illumination light EL on the reticle R, and formed on the reticle R. The exposed pattern is transferred and exposed onto the wafer W via the projection optical system PL. By repeatedly performing such an exposure operation, the pattern formed on the reticle R is sequentially exposed to each shot area on the wafer W.

  At this time, if there is uneven illumination in the exposure illumination light EL irradiated to the reticle R, the integrated exposure amount becomes non-uniform, and the line width of the pattern formed on the wafer W becomes non-uniform. Since the non-uniform line width causes a failure such as a disconnection, it is necessary to make the integrated exposure amount by the illumination light EL for exposure uniform.

  Here, the principle of correcting uneven exposure due to uneven illumination will be described. FIGS. 5A and 5B are diagrams for explaining uneven illuminance of the exposure illumination light. FIGS. 5A to 5C show the form of uneven illuminance (distribution), and FIGS. FIG. 4 is a diagram showing the shape of the opening M of the variable slit device 100 for correcting these uneven illuminances, that is, the shape of the passage region of the illumination light EL formed by the light shielding portions 10 and 20.

  The illumination light EL for exposure is usually formed in a slit shape, and irradiates the wafer W via the reticle R. Then, by scanning the reticle R and the wafer W in the direction of the slit width S of the exposure illumination light EL, the pattern of the reticle R is transferred to a rectangular shot area formed on the wafer W. At this time, if the illuminance of the exposure illumination light EL is uniform and the scanning speed is constant, the integrated exposure amount is uniform, and the shot area on the wafer W should be uniformly exposed.

However, in practice, the illuminance of the exposure illumination light EL is often not uniform. For example, as shown in FIG. 5A, the illuminance of the exposure illumination light EL is higher than an appropriate value at the center. Then, a state occurs in which both ends (the end on the ± X ₀ side) are lowered. When exposure processing is performed with such uneven illumination light EL for exposure, the central portion of the shot area is so-called overexposed and both ends are underexposed. As a result, the exposure of the photosensitive material (photoresist) becomes non-uniform, and the line width formed on the wafer W becomes non-uniform.

  Therefore, it is necessary to correct the non-uniformity of the illumination intensity of the exposure illumination light EL as described above. As a correction method, in a place where the illuminance is higher than an appropriate value (overexposure), the area irradiated with the exposure illumination light EL is reduced in order to reduce the exposure amount. That is, the slit width S is narrowed. Conversely, at a place where the illuminance is lower than the appropriate value (underexposure), the area irradiated with the exposure illumination light EL is increased in order to increase the exposure amount. That is, the slit width S is increased. That is, the variable slit device 100 adjusts the slit width S so that the integrated exposure amount becomes substantially uniform.

  In the above-described example, as shown in FIG. 5D, the light-shielding portion 10 of the variable slit device 100 is driven so that the slit width S at the center is narrowed while the slit width S at both ends is widened. . As a result, the exposure amount at the central portion decreases, while the exposure amount increases at both ends, so that it is possible to correct the exposure unevenness caused by the uneven illumination intensity of the exposure illumination light EL.

  As for the illuminance unevenness of the illumination light EL for exposure, as in the example described above, the quaternary unevenness in the form of a quaternary curve in addition to the secondary unevenness in which the illuminance changes in a quadratic curve shape (FIG. 5A) (FIG. 5B) or random unevenness (FIG. 5C) in which illuminance unevenness occurs randomly.

  In the case of secondary unevenness, as described above, the exposure amount can be adjusted substantially uniformly by changing the slit width S into a quadratic curve (FIG. 5D). In the case of quaternary unevenness or random unevenness, the exposure amount is substantially uniform by changing the slit width S as shown in FIGS. 5E to 5F in accordance with the illuminance distribution. It is possible to suppress the occurrence of uneven exposure due to uneven illumination.

  Note that the variable slit device 100 is not limited to correcting exposure unevenness due to uneven illumination. For example, when the photoresist film thickness is uneven, the slit width S of the variable slit device 100 can be changed in accordance with the uneven film thickness. That is, in a region where the photoresist film is thick, the slit width S is widened to increase the exposure amount. On the other hand, in a thin region, the slit width S is narrowed to reduce the exposure amount. It is also possible to expose substantially uniformly. As described above, the uneven exposure due to the uneven film thickness of the photoresist can also be corrected.

Next, a specific operation of the variable slit device 100 when correcting uneven exposure due to uneven illuminance or the like will be described.
First, the exposure amount of the illumination light EL for exposure is measured. The exposure amount distribution is measured by an illuminance meter (measurement unit) 230 disposed in the optical path of the exposure illumination light EL. The illuminance meter 230 is arranged in the vicinity of a position conjugate with the pattern of the reticle R. For example, as shown in FIG. 2, the wafer W is arranged flush with the wafer W on the wafer stage WS, and is configured to move on the optical path of the exposure illumination light EL during measurement. Then, the exposure amount is measured every shot area, every wafer W, or every lot, and the measurement result is sent to the main control system 220.

  Note that the exposure amount may be indirectly measured by actually measuring the line width on the exposed wafer W without using the illuminance meter 230. Then, the exposure illumination light EL for the wafer W to be subjected to the exposure process may be corrected thereafter.

  By measuring the line width of the pattern actually formed on the wafer W, causes other than the illuminance unevenness of the illumination light EL (for example, synchronization error and focus following error during scan exposure, resist coating unevenness on the wafer W, etc. ) Can be corrected all at once. Further, the timing (frequency) of measuring the exposure amount may be any shot area, wafer W, or lot. The line width measurement on the wafer W is performed at a plurality of locations in at least one shot area. And the correction value of the slit width S is calculated | required according to the position where the illumination light EL in a shot area is irradiated.

  In the main control system 220 to which the measurement result of the exposure amount is sent, the measurement unit 221 analyzes the measurement result, and forms of illuminance unevenness of the illumination light EL for exposure (secondary unevenness, fourth-order unevenness, sixth-order unevenness, random Unevenness etc.) is determined. Then, the shape (slit width S) of the illumination light EL for exposure necessary for correcting the uneven exposure due to the uneven illuminance is obtained, and furthermore, the blades of the light shielding portions 10 for forming the shape are obtained. A driving amount is required.

  Then, the main control system 220 instructs the variable slit device 100 based on the obtained blade driving amount to drive the linear actuator 70 of the actuator unit 50 to drive each blade of the light shielding unit 10.

In this manner, the variable slit device 100 is driven according to the illuminance unevenness of the exposure illumination light EL, and the slit width S of the exposure illumination light EL is partially changed.
In the present embodiment, the passage region of the illumination light EL is limited by the second light shielding unit 20 having an edge defined by a function including a second-order function component, a fourth-order function component, or a sixth-order function component. The first light shielding unit 10 corrects the illuminance unevenness of the component that cannot be corrected by the second light shielding unit 20. In other words, in the present embodiment, the second light-shielding unit performs the illuminance unevenness adjustment, and the first light-shielding unit 10 performs fine adjustment of the illuminance unevenness.

  For this reason, the stroke of actuator 70 itself as a drive means in the 1st light-shielding part 10 can be shortened. That is, there is an advantage that the accuracy of positioning of the blade 30 by the actuator 70 can be increased compared with the case where the stroke of the actuator 70 is lengthened by making the second light shielding portion 20 linear, and consequently the exposure on the wafer W. The quantity distribution can be adjusted with high accuracy.

  In the micro fly's eye lens 136 in the above-described embodiment, a large number of micro lens surfaces are formed on one light-transmitting substrate by applying the MEMS technology (lithography + etching or the like). In this case, since it is required to manufacture all the micro-refractive surfaces simultaneously by an etching process in which it is difficult to obtain a good surface shape as compared with the polishing process, the yield rate tends to be low. Here, when there is a manufacturing error on the minute refractive surface of the micro fly's eye lens 136, the illuminance distribution on the irradiated surface is affected.

  In the micro fly's eye lens 136 of each of the embodiments described above, the illuminance distribution can be corrected by the second light-shielding unit 20 having a curved edge defined by a function including a second-order or higher, preferably a fourth-order or higher component. Accordingly, since the tolerance can be given to the surface shape of the micro-refractive surface of the micro fly's eye lens, that is, the tolerance of the micro fly's eye lens can be relaxed by the illuminance distribution that can be corrected by the second light shielding unit 20. Therefore, it is possible to achieve an improvement in the non-defective rate in manufacturing the micro fly's eye lens.

  Further, as described above, the reticle R can be illuminated under illumination conditions such as a ring zone, a small circle, a large circle, or a fourth. Therefore, the shape (slit width) of the exposure illumination light EL once set for each illumination condition is stored in the main control system 220, and the shape of the exposure illumination light EL is changed every time the illumination condition is changed. The light shielding unit 10 of the variable slit device 100 may be driven so that Alternatively, the variable slit device 100 may be provided so as to be movable in the optical axis direction, and set to an optimal position in the optical axis direction of the variable slit device 100 each time the illumination condition is changed.

  In addition, an actuator may be provided in the second light-shielding unit 20, and the second light-shielding unit 20 may be provided so as to be rotatable about an axis parallel to the optical axis so as to correct an inclination component (primary component) of uneven illuminance. At this time, the first light-shielding unit 10 may correct an error of higher-order components of illuminance unevenness associated with the rotation operation of the second light-shielding unit 20. If the error of the higher-order component is negligible, correction by the first light shielding unit 10 is unnecessary.

  The operation procedure shown in the above-described embodiment, or various shapes and combinations of the constituent members are examples, and various changes can be made based on process conditions, design requirements, and the like without departing from the gist of the present invention. For example, the present invention includes the following modifications.

  In the above-described embodiment, the case where a so-called comb-shaped light-shielding portion in which a plurality of blades are arranged in a comb-like shape with almost no gap is used for one of the light-shielding portions has been described. . As shown in JP-A-10-340854, a so-called chain-type light-shielding portion in which a plurality of blades are rotatably connected at both end portions may be used.

As a linear actuator, a rack and pinion mechanism using a linear motor or a servo motor, a cam mechanism, or the like can be used in addition to a voice coil motor.
The use of the exposure apparatus is not limited to the exposure apparatus for manufacturing a semiconductor device. For example, an exposure apparatus for liquid crystal that exposes a liquid crystal display element pattern on a square glass plate or a thin film magnetic head Widely applicable to exposure apparatus.

The light source of the exposure apparatus to which the present invention is applied includes not only KrF excimer laser (248 nm), ArF excimer laser (193 nm), F ₂ laser (157 nm), but also g-line (436 nm) and i-line (365 nm). ) Can be used. Further, the magnification of the projection optical system may be not only a reduction system but also an equal magnification or an enlargement system.

  An exposure apparatus to which the present invention is applied assembles various subsystems including the constituent elements recited in the claims of the present application so as to maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. It is manufactured by. In order to ensure these various accuracies, before and after assembly, various optical systems are adjusted to achieve optical accuracy, various mechanical systems are adjusted to achieve mechanical accuracy, and various electrical systems are Adjustments are made to achieve electrical accuracy. The assembly process from the various subsystems to the exposure apparatus includes mechanical connection, electrical circuit wiring connection, pneumatic circuit piping connection and the like between the various subsystems. Needless to say, there is an assembly process for each subsystem before the assembly process from the various subsystems to the exposure apparatus. When the assembly process of the various subsystems to the exposure apparatus is completed, comprehensive adjustment is performed to ensure various accuracies as the entire exposure apparatus. The exposure apparatus is preferably manufactured in a clean room where the temperature, cleanliness, etc. are controlled.

In the exposure apparatus according to the above-described embodiment, the illumination optical device illuminates the mask (reticle) (illumination process), and the projection optical system is used to expose the transfer pattern formed on the mask onto the photosensitive substrate (exposure). Step), a micro device (semiconductor element, imaging element, liquid crystal display element, thin film magnetic head, etc.) can be manufactured. Refer to the flowchart of FIG. 6 for an example of a method 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 the above-described embodiment. To explain.

First, in step 301 of FIG. 6, 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 lot of wafers. Thereafter, in step 303, using the exposure apparatus of the above-described embodiment, the pattern image 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 the exposure apparatus of the above-described 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. 7, in the pattern forming process 401, a so-called photolithography process is performed in which the mask pattern is transferred and exposed to a photosensitive substrate (such as a glass substrate coated with a resist) using the exposure apparatus of the above-described embodiment. . 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, the present invention is applied to an illumination optical apparatus having a specific configuration as shown in FIG. 1, but various modifications can be made to the specific configuration of the illumination optical apparatus. It is. For example, an optical system from the diffractive optical element 132 as the first integrator to the micro fly's eye lens 136 as the second integrator in the above-described embodiment is disclosed in Japanese Patent Laid-Open Nos. 2001-85293 and 2002-231619. The present invention can also be applied to an illumination optical device obtained by replacing the optical system of the corresponding part.

  In the above-described embodiment, the present invention has been described by taking a projection exposure apparatus including an illumination optical apparatus as an example. However, the present invention is applied to a general illumination optical apparatus for illuminating a surface to be irradiated other than a mask. Obviously it can be done.

Diagram showing variable slit device Schematic diagram showing exposure illumination system and exposure apparatus The perspective view which shows the structure of the micro fly's eye lens of FIG. 2 roughly The figure explaining the effect | action of the micro fly's eye lens of FIG. The figure explaining the illumination intensity nonuniformity of the illumination light for exposure Flow chart of a technique for obtaining a semiconductor device as a micro device Flow chart of a method for obtaining a liquid crystal display device as a micro device

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 1st light-shielding part 20 2nd light-shielding part 30,40 Blade 50,60 Actuator part (drive mechanism)
72 Rod (first push / pull member)
74 (74a, b) Rod (second push / pull member)
100 Variable slit device 121 Exposure illumination system (illumination device)
220 Main control system (control device)
221 Calculation unit 230 Illuminance meter (measurement unit)
R reticle (mask)
W Wafer (Substrate)
EL illumination light, exposure illumination light L1, L2 long side EX exposure device

Claims (11)

In the variable slit device that forms a slit-shaped illumination area on the irradiated surface based on the light flux from the light source,
A first light-shielding portion having a plurality of blades for defining one long side of the slit-shaped illumination area;
A second light-shielding portion that defines the other long side of the slit-shaped illumination area;
A driving mechanism for driving the first light-shielding portion and changing the shape of the illumination light in the longitudinal direction;
The second light-shielding portion is formed in a curved shape including a second-order or higher component in order to correct a second-order or higher component of the illuminance distribution unevenness on the irradiated surface. apparatus.   The variable slit device according to claim 1, wherein the curve including the second-order or higher-order component of the second light shielding unit includes a fourth-order or higher-order component.   The variable slit device according to claim 2, wherein the curve including the second-order or higher-order component of the second light-shielding unit includes at least one of a fourth-order component and a sixth-order component. In the illumination optical device that illuminates the illuminated surface based on the light flux from the light source,
A variable slit device according to any one of claims 1 to 3,
An optical integrator disposed in an optical path between the light source and the irradiated surface;
The variable optical slit device corrects at least a part of illuminance distribution unevenness on the irradiated surface caused by the optical integrator.   The illumination optical apparatus according to claim 4, wherein the optical integrator includes a wavefront division type integrator that forms a plurality of light beams based on an incident light beam.   The wavefront division type integrator includes a first one-dimensional cylindrical lens array arranged at a pitch along a predetermined first direction, and a second one arranged at a pitch along a second direction intersecting the first direction. The illumination optical apparatus according to claim 5, further comprising: a one-dimensional cylindrical lens array.   The illumination optical apparatus according to claim 6, wherein the first and second one-dimensional cylindrical lens arrays are integrally provided on one light transmissive substrate. An exposure apparatus comprising the illumination optical apparatus according to any one of claims 4 to 7 for illuminating a mask, and exposing a pattern of the mask onto a photosensitive substrate. A projection optical system disposed in an optical path between the mask and the photosensitive substrate to form a pattern image of the mask on the photosensitive substrate;
A stage mechanism for performing exposure while moving the photosensitive substrate along a predetermined scanning direction with respect to the projection optical system;
An exposure apparatus, wherein a shape of a light passage region formed by the first light shielding portion and the second light shielding portion of the variable slit device is changed according to a position in a non-scanning direction crossing the scanning direction.   An exposure method comprising: illuminating a mask via the illumination optical device according to any one of claims 4 to 7, and exposing a pattern formed on the mask onto a photosensitive substrate.   While projecting a pattern image of the mask onto the photosensitive substrate via a projection optical system disposed in an optical path between the mask and the photosensitive substrate, the photosensitive substrate with respect to the projection optical system Is moved along a predetermined scanning direction to perform exposure, and light formed by the first light shielding portion and the second light shielding portion of the variable slit device according to the position in the non-scanning direction across the scanning direction. The exposure method according to claim 10, wherein the shape of the passing region is changed.