JP6761306B2 - Illumination optics, lithography equipment, and article manufacturing methods - Google Patents

Description

The present invention relates to illumination optics, lithographic equipment, and article manufacturing methods.

In an exposure apparatus that projects a pattern formed on a mask onto a substrate coated with a photosensitive material such as a resist, improvement in illuminance uniformity on an illuminated surface such as a mask surface or a substrate surface is required. As a method for improving the illuminance uniformity, it is known to use an illumination optical system equipped with a rod-type optical integrator. By using a rod-type optical integrator, it is possible to make the illuminance distribution on the rod ejection surface uniform by superimposing the illumination light from the secondary light source formed according to the number of internal reflections in the rod at the rod ejection end. it can.

However, in an illumination optical system equipped with a rod-type optical integrator, the illuminance distribution on the illuminated surface becomes non-uniform due to various factors such as dirt and eccentricity of the optical system and unevenness of the antireflection film. May be accepted. In response to this problem, Patent Document 1 has a configuration in which a plurality of light quantity adjusting units provided corresponding to a plurality of secondary light source images are arranged at positions that are optically conjugated with the injection surface of the rod-type optical integrator. Is disclosed.

Japanese Unexamined Patent Publication No. 2000-269114

However, in the illumination optical system disclosed in Patent Document 1, once the angle distribution condensing on the illuminated surface (hereinafter referred to as “effective light source distribution”) is determined, the amount of illuminance distribution correction on the illuminated surface is fixed. It becomes. Therefore, it has been difficult to correct the illuminance non-uniformity (hereinafter referred to as "illuminance unevenness") peculiar to each airframe caused by the film formation state of the antireflection film and the assembly accuracy. Further, when the optical element deteriorates after using the device for a long period of time and the illuminance unevenness changes with time, it is necessary to replace the adjusting unit as appropriate.

An object of the present invention is, for example, to provide a technique advantageous for improving the correction performance of illuminance unevenness.

According to one aspect of the present invention, an illumination optical system that illuminates an illuminated surface using light from a light source, an optical integrator arranged between the light source and the illuminated surface, and the optical integrator. The optical integrator is a rod-type optical integrator that reflects the incident light on the inner surface, and has an optical filter having an adjusting unit for adjusting the intensity of the light incident on the illumination optical system, and is perpendicular to the optical axis of the illumination optical system. Provided is an illumination optical system characterized in that the illumination on the illuminated surface is changed by changing the position of the adjustment unit in a different direction.

According to the present invention, a technique advantageous for improving the correction performance of illuminance unevenness is provided.

The figure which shows the structure of the exposure apparatus. The schematic diagram which shows the relationship between the adjustment part and a secondary light source. (A) is a diagram showing the imaging relationship between the adjustment unit and the injection end face of the optical integrator, and (B) and (C) are diagrams showing an arrangement example of the adjustment unit on the optical filter. The figure explaining the operation of an optical filter. The figure explaining the correction method of the illuminance unevenness. The flowchart which shows the correction procedure of the inclined illuminance unevenness. The flowchart which shows the correction procedure of the illuminance unevenness of optical axis symmetry. The figure explaining the operation of an optical filter. The figure explaining the correction method of the illuminance unevenness. The figure explaining the operation of an optical filter. The figure explaining the operation of an optical filter.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and the following embodiments merely show specific examples of the embodiment of the present invention. In addition, not all combinations of features described in the following embodiments are essential for solving the problems of the present invention.

<First Embodiment>
FIG. 1 is a schematic view showing the configuration of the exposure apparatus 100 according to the present embodiment. The exposure apparatus 100 is used, for example, in a lithography process in a semiconductor device manufacturing process, and is a projection type that exposes (transfers) an image of a pattern formed on a reticle R (mask) onto a wafer W as a substrate. It is an exposure device. In FIG. 1, the Z axis is taken along the normal direction of the wafer W, and the X axis and the Y axis are taken in the direction perpendicular to each other in the plane parallel to the wafer W plane. The exposure apparatus 100 includes an illumination optical system 101, a reticle stage 102, a projection optical system 103, a wafer stage 104, and a control unit 105.

The illumination optical system 101 adjusts the light (luminous flux) from the discharge lamp 1 which is a light source to illuminate the reticle R which is an illuminated region. The discharge lamp 1 can be, for example, an ultra-high pressure mercury lamp that supplies light such as i-line (wavelength 365 nm). Further, the present invention is not limited to this, and for example, a KrF excimer laser that supplies light having a wavelength of 248 nm, an ArF excimer laser that supplies light having a wavelength of 193 nm, and an F2 laser that supplies light having a wavelength of 157 nm may be used. When the illumination optical system 101 and the projection optical system 103 are composed of a reflection / refraction system or a reflection system, a charged particle beam such as an X-ray or an electron beam may be used as the light source.

The reticle R is an original plate made of, for example, quartz glass, in which a pattern (for example, a circuit pattern) to be transferred is formed on the wafer W. The reticle stage 102 holds the reticle R and is movable in each of the X and Y axial directions. The projection optical system 103 projects the light that has passed through the reticle R onto the wafer W at a predetermined magnification. The wafer W is a substrate made of, for example, single crystal silicon, on which a resist (photosensitive material) is coated on the surface. The wafer stage 104 holds the wafer W via a wafer chuck (not shown) and is movable in each axial direction of X, Y, and Z (which may include ωx, ωy, and ωz, which are the respective rotation directions). .. The wafer stage 104 can be driven by the wafer stage drive unit 114.

The illumination optical system 101 includes an elliptical mirror 2, a first relay optical system 3, an optical integrator 4, and a second relay optical system 5 in this order from the discharge lamp 1 toward the reticle R, which is an illuminated area. The elliptical mirror 2 is a condensing mirror that collects the light (luminous flux) emitted from the discharge lamp 1 at the second focal position F2. The light emitting portion in the bulb portion of the discharge lamp 1 is arranged in the vicinity of the first focal point F1 of the elliptical mirror 2, for example. The first relay optical system 3 as an imaging optical system includes a lens front group 3a (first lens) composed of a single or a plurality of lenses and a lens rear group 3b (second lens) composed of a single or a plurality of lenses. Including. The front lens group 3a makes the light from the light source parallel light. The rear lens group 3b collects the light parallelized by the rear lens group 3a onto the incident end surface 4a of the optical integrator 4. The second focal position F2 and the incident end surface 4a of the optical integrator 4 are optically conjugated by the front lens group 3a and the rear lens group 3b. In the present embodiment, the optical axis of the illumination optical system 101, particularly the optical system including the first relay optical system 3, the optical integrator 4, and the second relay optical system 5, is in the Z-axis direction.

In the present embodiment, the optical integrator 4 is a rod-type optical integrator that reflects incident light on the inner surface and forms a plurality of secondary light source images corresponding to the number of reflections thereof. The shape of the optical integrator 4 is, for example, a quadrangular prism. That is, the shapes of the incident end face and the ejection end face parallel to the XY plane of the optical integrator 4 are rectangular shapes similar to the illuminated surface. However, such a shape is an example and does not prevent the application of a member having the same action as the optical integrator 4. For example, the optical integrator 4 may be composed of a hollow rod that forms a reflective surface inside. Further, the cross-sectional shape of the incident end surface 4a and the injection end surface 4b of the optical integrator 4 on the XY plane may be a polygon other than a quadrangle.

Between the discharge lamp 1 and the optical integrator 4, the optical filter 6 is arranged perpendicular to the optical axis in the vicinity of the reticle R, that is, the conjugate surface S1 conjugated to the wafer W. The optical filter 6 is configured to be movable two-dimensionally along the XY plane, and the movement is performed by, for example, the filter driving unit 7. The optical filter 6 is included in the first relay optical system 3, for example, as shown in FIG. 1, and may be arranged between the front lens group 3a and the rear lens group 3b. The optical filter 6 has a plurality of adjusting units for adjusting the intensity of light incident on the optical integrator 4, which are provided according to the number of secondary light source images formed by the optical integrator 4. The optical action of the optical filter 6 will be described in detail later.

The rear lens group 3b is arranged at a position separated by a focal length from the position of the virtual image plane S2 of the secondary light source formed by the optical integrator 4, and the illumination light emitted from the optical filter 6 substantially parallel to the optical axis is emitted. , The light is once focused on the virtual image plane S2.

The incident end surface 4a of the optical integrator 4 is arranged in the vicinity of the virtual image surface S2. The illumination light collected by the rear lens group 3b is reflected and emitted a plurality of times on the inner surface of the optical integrator 4. The illumination light emitted from the optical integrator 4 is emitted as if it were directed from a virtual image of a discrete secondary light source corresponding to the number of reflections. Therefore, the angle of the illumination light emitted from the optical integrator 4 corresponds to the angle of emission of the illumination light from the virtual image of the secondary light source arranged on the virtual image surface S2.

The injection end surface 4b of the optical integrator 4 is superimposed by a plurality of light source images arranged on the virtual image surface S2 and is uniformly illuminated. The light emitted from the ejection end surface 4b of the optical integrator 4 passes through the second relay optical system 5 and then illuminates the reticle R, which is the illuminated surface. The second relay optical system 5 includes a lens front group 5a composed of a single lens or a plurality of lenses that makes the light from the emission end surface 4b of the optical integrator 4 parallel. The front lens group 5a is configured to be movable in the optical axis direction (Z-axis direction) of the second relay optical system 5. The second relay optical system 5 further includes a lens rear group 5b composed of a single lens or a plurality of lenses that collects the light parallel light in the lens front group 5a onto the illuminated surface. The movement of the front lens group 5a is performed by the lens driving unit 51. By moving the front lens group 5a in the direction of the optical axis, it is possible to change the distortion while keeping the focal length substantially unchanged. Due to this action, it is possible to raise or lower the ambient illuminance by moving the front lens group 5a.

In the present embodiment, the injection end surface 4b of the optical integrator 4 is arranged at the front focal position of the lens front group 5a, and the injection end surface 4b of the optical integrator 4 is optically conjugated with the reticle R which is the illuminated surface. It has become. Strictly speaking, the position of the injection end face 4b may be slightly shifted from the conjugate in order to prevent foreign matter on the injection end face 4b of the optical integrator 4 from being transferred. Then, the light emitted from the reticle R, that is, the image of the mask pattern is transferred onto the wafer W via the projection optical system 103.

The illuminance distribution measurement unit 115 measures the illuminance distribution on the reticle R, which is the illuminated surface. The control unit 105 controls the discharge lamp 1, the filter drive unit 7, the lens drive unit 51, the wafer stage drive unit 114, and the illuminance distribution measurement unit 115. The control unit 105 may include a storage unit 105a that stores various data required for control.

Next, the optical action of the optical filter 6 will be described. FIG. 2 is a diagram schematically showing the relationship between a plurality of adjusting units provided on the optical filter and a plurality of secondary light sources formed by the optical integrator 4. FIG. 2 shows an optical path of illumination light emitted from the optical filter 6 in parallel with the optical axis. The adjustment unit 60 on the optical axis provided on the optical filter 6 adjusts the intensity of the light flux from the secondary light source 40 that is not reflected by the inner surface of the optical integrator 4. Further, the pair of adjusting units 61a and 61b adjacent to both outer sides of the adjusting unit 60 adjust the intensity of the light flux from the secondary light source images 41a and 41b reflected once on the inner surface of the optical integrator 4. Further, the pair of adjusting portions 62a and 62b adjacent to both outer sides of the adjusting portions 61a and 61b adjust the intensity of the light flux from the secondary light source images 42a and 42b reflected twice on the inner surface of the optical integrator 4. According to such a configuration, the transmittance can be controlled independently for the luminous flux of each of the plurality of secondary light sources formed by the optical integrator 4.

The adjusting portions 60, 61a, 61b, 62a, 62b are arranged in the vicinity of the conjugate surface S1 conjugated with the injection end surface 4b of the optical integrator 4. Therefore, the shape of one adjusting unit corresponds to the illumination region on the reticle R or the wafer W of FIG. 1, and the transmittance distribution of the adjusting units 60, 61a, 61b, 62a, 62b is on the wafer W. It will be reflected in the illuminance distribution of the illumination area of.

FIG. 3A is a diagram illustrating an imaging relationship between each adjusting portion of the optical filter 6 and the injection end surface 4b of the optical integrator 4. In the optical integrator 4, the luminous flux from adjacent secondary light sources is inverted. Therefore, when the direction of the image formed on the injection end surface 4b of the optical integrator 4 is "F", the images of the adjacent adjustment portions are in opposite directions, and are in a mirror image relationship with each other.

FIG. 3B is a schematic view of the optical filter 6 arranged in the vicinity of the conjugate surface S1 as viewed from the incident side. Here, a pattern filter (or a light-shielding member) is used as the adjusting unit. In the present embodiment, the plurality of pattern filters constituting the plurality of adjustment units are arranged at predetermined positions on the optical filter corresponding to the mirror image relationship in the plurality of secondary light source images of the optical integrator 4. The optical filter 6 includes a plurality of first regions A and B, and a plurality of second regions excluding the first region. Here, the plurality of first regions A and B are regions where images in the same orientation are formed on the injection end faces 4b of the optical integrator 4. Further, the plurality of second regions are regions where an image having a mirror image relationship with the image of the first region is formed on the injection end surface 4b of the optical integrator 4. In the present embodiment, on the surface of the optical filter 6, rectangular pattern filters 6A and 6B are arranged in a plurality of first regions A and B, respectively, corresponding to a plurality of secondary light source images of the optical integrator 4. There is. The pattern filters 6A and 6B may be arranged in at least a part of the plurality of first regions A and B, not all of them.

In the present embodiment, by arranging circular pattern filters having different sizes as the pattern filters 6A and 6B, each pattern filter portion is provided with the effects as shown in FIGS. 4A and 4B. ing. By appropriately adjusting the diameter, transmittance, and arrangement of each pattern filter, the illuminated surface is finally approximated as shown in FIG. 4 (C) showing the sum of FIGS. 4 (A) and 4 (B). The effect of increasing the illuminance in the peripheral portion of the illuminated surface can be obtained in proportion to the square of the image height.

Generally, in the illumination optical system of a projection exposure apparatus, if an attempt is made to achieve both a uniform numerical aperture and a uniform illuminance distribution on an illuminated surface, the ambient illuminance decreases due to the angular characteristics of the antireflection film used for the lens. There is a tendency. Therefore, an optical filter having an action of increasing the illuminance in the surroundings as in the present embodiment is effective for correcting the illuminance distribution.

Further, the luminous flux incident on the optical integrator 4 is adjusted so as to have an illuminance distribution symmetrical with respect to the optical axis. As a result, the effective light source distribution on the illuminated surface is symmetrical with respect to the main ray, so that image deviation does not occur with respect to defocus. As a result, exposure with good telecentricity can be realized.

If the illumination light incident on the optical integrator 4 has an asymmetric illuminance distribution with respect to the optical axis, the symmetry of the effective light source distribution is lost, and the image performance is affected in the form of a shift in telecentricity. .. However, according to the present embodiment, since the pattern filters are arranged symmetrically on the optical axis, there is almost no deviation in telecentricity.

In this embodiment, two types of pattern filters 6A and 6B are used as the adjusting unit, but for example, by changing the density of fine dot patterns, one type of pattern is approximately proportional to the square of the image height. It is also possible to create an illuminance distribution.

Hereinafter, a method for correcting illuminance unevenness as shown in FIG. 5A will be described. The illuminance unevenness in FIG. 5 (A) forms an oblique illuminance unevenness as shown in FIG. 5 (B) and an arc shape symmetrical with the optical axis as shown in FIG. 5 (C), and goes to the periphery. It can be decomposed into uneven illuminance, which decreases the illuminance. These can be separated by calculating the average illuminance and inclination component for each image height from the illuminance distribution.

First, a method for correcting the inclined illuminance unevenness in FIG. 5B will be described. As described above, the optical filter 6 of the present embodiment has the effect of increasing the illuminance in the peripheral portion in proportion to the square of the image height. At this time, if the incident end surface 4a of the optical integrator 4 is equivalent to the illuminated surface and a normalized XY coordinate system is used, the effect z of the illuminance distribution adjustment by the optical filter 6 is z = a (x ² + y ² ). Can be written. Here, a is a constant.

The pattern filters 6A and 6B of the optical filter 6 are arranged in at least a part of a plurality of first regions A and B where images in the same orientation are formed on the injection end faces 4b of the optical integrator 4. The optical filter 6 can move in a direction along the plurality of first regions A and B and a plurality of second regions other regions, that is, in a direction along the XY plane. That is, it is possible to change the position of the optical filter 6 in the direction (X direction or Y direction) perpendicular to the optical axis (Z axis) of the illumination optical system. Here, even if the optical filter 6 is moved in the direction along the XY plane, the effects of the illuminance distribution change on the illuminated surface given by the pattern filters 6A and 6B are not canceled out with each other.

Therefore, the effect z'of the illuminance distribution adjustment by the optical filter 6 when the optical filter 6 is moved by a predetermined distance δ in the X and Y directions can be written as z'= a ((x + δ) ² + (y + δ) ² ). Here, a is a constant. That is, since the first-order terms of x and y depending on δ are generated, an inclined illuminance distribution can be generated.

FIG. 6 is a flowchart showing a procedure for correcting inclined illuminance unevenness. In S601, the control unit 105 calculates the illuminance unevenness on the illuminated surface based on the illuminance distribution data measured by the illuminance distribution measurement unit 115 (illuminance unevenness measurement 1). Assuming that the maximum value of the illuminance value on the illuminated surface is Smax and the minimum value is Smin, the illuminance unevenness S is calculated by, for example, the following equation.
S = (Smax-Smin) / (Smax + Smin)
After that, the control unit 105 moves the optical filter 6 in the X direction by a predetermined distance δ in S602, and measures the illuminance unevenness on the illuminated surface in S603 (illuminance unevenness measurement 2). Next, the control unit 105 moves the optical filter 6 in the Y direction by a predetermined distance δ in S604, and measures the illuminance unevenness on the illuminated surface in S605 (illuminance unevenness measurement 3). After that, the control unit 105 calculates the amount of change in the illuminance unevenness from the results of the illuminance unevenness measurements 1, 2 and 3 in S606 and stores it in the storage unit 105a. This amount of change corresponds to the inclination of the above-mentioned inclined illuminance distribution.

Next, in S607, the control unit 105 calculates the moving direction and the moving amount of the optical filter 6 based on the change amount calculated in S606. Then, the control unit 105 moves the optical filter 6 in the calculated direction by the filter drive unit 7 by the calculated movement amount.

After that, in S609, the control unit 105 measures the illuminance unevenness on the illuminated surface again (illuminance unevenness measurement 4), and in S610, confirms whether the illuminance unevenness is within a predetermined allowable range. If the illuminance unevenness is within the permissible range, the process ends. On the other hand, if the illuminance unevenness is not within the permissible range, the process proceeds to S611, the result of the illuminance unevenness measurement 4 is fed back, and the process returns to S607 to recalculate the moving direction and the moving amount of the optical filter 6.

Next, a method of correcting the optical axis-symmetrical illuminance unevenness of FIG. 5C will be described with reference to the flowchart of FIG. 7. When the optical axis-symmetrical illuminance unevenness occurs, the peripheral illuminance correction amount is adjusted. As described above, the second relay optical system 5 has a configuration in which the front lens group 5a is moved in the optical axis direction to change the distortion while substantially not changing the focal length. This makes it possible to raise or lower the ambient illuminance by moving the front lens group 5a.

In S701, the control unit 105 obtains the amount of change in the illuminance of the outermost peripheral portion of the illuminated surface when the lens front group 5a is moved by a predetermined distance Δ in the optical axis direction by the illuminance distribution measurement unit 115, and this amount of change. Is stored in the storage unit 105a (illuminance unevenness measurement 1). Note that this S701 may be performed in advance by simulation or the like. In S702, the control unit 105 calculates the amount of movement of the front lens group 5a in the optical axis direction based on this amount of change. In S703, the control unit 105 moves the lens front group 5a in the optical axis direction by the lens driving unit 51 with the calculated movement amount.

After that, in S704, the control unit 105 again obtains the amount of change in the illuminance of the outermost peripheral portion of the illuminated surface when the lens front group 5a is moved by a predetermined distance Δ in the optical axis direction (illuminance unevenness measurement 2), and S705. Then, it is confirmed whether the fluctuation amount is within the predetermined allowable range. If the amount of fluctuation is within the permissible range, the process ends. On the other hand, if the fluctuation amount is not within the permissible range, the process proceeds to S706, the result of the illuminance unevenness measurement 2 is fed back, and the process returns to S703 to recalculate the movement amount of the optical filter 6. In this way, the control unit 105 feedback-controls the movement amount of the optical filter 6 so that the illuminance unevenness calculated from the illuminance distribution measured by the illuminance distribution measurement unit 115 is within an allowable range.

More precise correction can be performed by both moving the optical filter 6 according to the control procedure of FIG. 6 and driving the front lens group according to the control procedure of FIG. 7 as described above. At this time, the control procedure of FIG. 6 and the control procedure of FIG. 7 by the control unit 105 may be executed in series or in parallel in chronological order.

The execution results of each of the control procedure of FIG. 6 and the control procedure of FIG. 7 can be stored in the storage unit 105a. When the execution is performed again under the same lighting conditions, the execution result can be called from the storage unit 105a to drive each element to the optimum position. As a result, the steps shown in FIGS. 6 and 7 can be omitted, and the inclined illuminance unevenness and the concentric illuminance unevenness (optical axis symmetric illuminance unevenness) can be quickly corrected.

Further, when the illumination optical system is used for a long period of time, it is conceivable that the transmittance of any lens in the apparatus deteriorates and illuminance unevenness in an inclined shape with rotational asymmetry occurs. Even in such a case, the control procedure of FIGS. 6 and 7 may be executed again to correct the inclined illuminance unevenness and the concentric illuminance unevenness (optical axis symmetric illuminance unevenness). ..

For example, in Japanese Patent Application Laid-Open No. 2001-135564, an optical filter is arranged near the incident surface of an optical integrator in which a plurality of microlenses are two-dimensionally arranged at a predetermined pitch. The optical filter has a light amount adjusting unit that can adjust the transmitted light amount in a plurality of regions corresponding to each of the plurality of minute lenses constituting the optical integrator. Even with such a configuration, it is possible to control the illuminance unevenness by moving the optical filter along the XY plane.

However, since an optical integrator in which a plurality of microlenses are two-dimensionally arranged at a predetermined pitch is generally expensive, the rod-type optical integrator according to the present embodiment is lower in cost. According to the configuration of the present embodiment using the rod-type optical integrator, the arrangement location of each adjustment unit is determined by utilizing the imaging relationship as shown in FIG. 3 (A). Specifically, the plurality of adjustment parts are optical filters so that the image of each adjustment part formed on the injection end face of the rod-type optical integrator by the light transmitted through each of the plurality of adjustment parts is oriented in the same direction. Placed on top. This makes it possible to control illuminance unevenness.

<Second Embodiment>
Next, the illumination optical system according to the second embodiment will be described. The schematic configuration of the device is the same as in FIG. FIG. 3C is a schematic view of the optical filter 6 according to the present embodiment as viewed from the incident side. On the surface of the optical filter 6, rectangular pattern filters 6C are arranged in a plurality of first regions C corresponding to a plurality of secondary light source images of the optical integrator 4, and a plurality of rectangular pattern filters 6D are arranged. It is arranged in the second area D. The pattern filters 6C and 6D may be arranged in at least a part of the plurality of first regions C and the plurality of second regions D, respectively, instead of all of them. Here, the plurality of first regions C are regions in which images in the same orientation are formed on the injection end faces 4b of the optical integrator 4. Further, the plurality of second regions D are regions where an image having a mirror image relationship with respect to the image of the plurality of first regions C is formed on the injection end surface 4b of the optical integrator 4.

In the present embodiment, the pattern filter 6C has an effect of increasing the illuminance of the peripheral portion of the illuminated surface approximately in proportion to the square of the image height, as shown in FIG. 8A. Further, the pattern filter 6D has the opposite characteristic, that is, the effect of lowering the illuminance in the peripheral portion approximately in proportion to the square of the image height as shown in FIG. 8 (B). By such a combination of the pattern filters 6C and 6D, the effects of the change in the illuminance distribution as a whole are configured to cancel each other out.

Hereinafter, a method for correcting inclined illuminance unevenness as shown in FIG. 9A will be described. Assuming that the incident end surface 4a of the optical integrator 4 is equivalent to the illuminated surface and has a normalized XY coordinate system, the effect z of the optical filter 6 can be expressed only in one dimension in the X direction for the sake of simplicity. Z = ax ² -ax ² = 0, which does not affect the illuminance distribution. Here, a is a constant.

The effect z'when the optical filter 6 is moved by a predetermined distance δ in the X direction can be written as z'= a (x + δ) ^2- a (x-δ) ² because the direction of δ changes in the pattern filters 6C and 6D. .. That is, since the first-order argument of x depending on δ is generated, an inclined illuminance distribution can be generated.

Also in the present embodiment, by executing the same procedure as the flowchart of FIG. 6, the inclined illuminance unevenness can be corrected so as to be flat as shown in FIG. 9B. As described above, when the decrease in peripheral illuminance of the secondary shape is originally small and the illuminance unevenness in the inclined shape is dominant, the configuration of the adjusting portion as in the present embodiment is effective for correcting the illuminance distribution.

<Third Embodiment>
Next, the illumination optical system according to the third embodiment will be described. In the present embodiment, the effects of the pattern filters 6C and 6D in the second embodiment are different. The pattern filter 6C in the present embodiment has an effect that the illuminance distribution changes approximately in proportion to the cube of the image height, as shown in FIG. 10A. Further, the pattern filter 6D has the opposite characteristic, that is, the effect that the illuminance distribution changes approximately in proportion to the cube of the image height as shown in FIG. 10 (B). By such a combination of the pattern filters 6C and 6D, the effects of the change in the illuminance distribution as a whole are configured to cancel each other out.

Similar to the second embodiment, the effect z of the optical filter 6 is z = ax ³ -ax ³ = 0 when expressed only in one dimension in the X direction, and does not affect the illuminance distribution. Here, a is a constant.

The effect z'when the optical filter 6 is moved by a predetermined distance δ in the X direction is z'= a (x + δ) ^3- a (x-δ) ³ because the direction of δ changes in the pattern filters 6C and 6D. .. In the present embodiment, since a delta-dependent quadratic argument of x is generated, a concentric quadratic illuminance distribution can be generated.

Also in the present embodiment, by executing the same procedure as the flowchart of FIG. 6, the illuminance distribution of the secondary shape as shown in FIG. 11 (A) is corrected so as to be flat as shown in FIG. 11 (B). be able to. As described above, when there is originally no inclined illuminance unevenness and concentric secondary illuminance unevenness is dominant, the configuration of the adjusting portion as in the present embodiment is effective for illuminance distribution correction.

Even if the illuminance distribution to be corrected is a high-order shape of the third or higher order, the illuminance unevenness can be corrected by appropriately setting the transmittance distribution of the pattern filter.

<Embodiment of Article Manufacturing Method>
The article manufacturing method according to the embodiment of the present invention is suitable for manufacturing articles such as microdevices such as semiconductor devices and elements having a fine structure, for example. The article manufacturing method of the present embodiment includes a step of transferring the pattern of the original plate to the substrate using the above-mentioned lithography apparatus (exposure apparatus, imprint apparatus, drawing apparatus, etc.) and processing the substrate to which the pattern is transferred in such a step. Including the process of Further, such a manufacturing method includes other well-known steps (oxidation, film formation, vapor deposition, doping, flattening, etching, resist peeling, dicing, bonding, packaging, etc.). The article manufacturing method of the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article as compared with the conventional method.

100: Exposure device, 101: Illumination optical system, 103: Projection optical system, 105: Control unit, 4: Optical integrator, 6: Optical filter

Claims (10)

An illumination optical system that illuminates the illuminated surface using light from a light source.
An optical integrator arranged between the light source and the illuminated surface,
An optical filter having an adjusting unit for adjusting the intensity of light incident on the optical integrator, and an optical filter.
Have,
The optical integrator is a rod-type optical integrator that reflects incident light on the inner surface.
The optical filter includes a plurality of first regions in which images in the same orientation are formed on the injection end faces of the rod-type optical integrator, and a plurality of images having a mirror image relationship with the image on the injection end faces. Including the second area of
The adjusting unit is not provided in the plurality of second regions, but is provided in the plurality of first regions.
An image formed on the injection end face of the rod-type optical integrator by light from the adjusting portion provided in the plurality of first regions, and the light from the plurality of second regions of the rod-type optical integrator. Illuminate the illuminated surface with an image formed on the injection end face.
An illumination optical system characterized in that the illuminance on the illuminated surface is changed by changing the position of the adjustment unit in a direction perpendicular to the optical axis of the illumination optical system. An illumination optical system that illuminates the illuminated surface using light from a light source.
An optical integrator arranged between the light source and the illuminated surface,
It has an optical filter having an adjusting unit for adjusting the intensity of light incident on the optical integrator.
The optical integrator is a rod-type optical integrator that reflects incident light on the inner surface.
The optical filter includes a plurality of first regions in which images in the same orientation are formed on the injection end faces of the rod-type optical integrator, and a plurality of images having a mirror image relationship with the image on the injection end faces. Including the second area of
The adjusting unit is arranged in a part of the plurality of first regions and a part of the plurality of second regions.
The number of the adjusting parts arranged in the part of the plurality of first regions and the number of the adjusting parts arranged in the parts of the plurality of second regions are the same.
The image formed on the injection end face of the rod-type optical integrator by the light from the adjustment unit arranged in the plurality of first regions and the light from the adjustment unit arranged in the plurality of second regions The illuminated surface is illuminated with an image formed on the injection end surface of the rod-type optical integrator.
And characteristics of illuminance distribution on the surface to be illuminated is adjusted by the adjusting portion of the first region, Ri and the Do different characteristics of illuminance distribution on the surface to be illuminated is adjusted by the adjusting portion of the second region,
The illumination optical system irradiation Meiko science system characterized by changing the illuminance on the surface to be illuminated by changing the position of the adjustment section in a direction perpendicular to the optical axis of the. Further having a first relay optical system arranged between the light source and the optical integrator and directing light from the light source to the optical integrator.
The first relay optical system includes a first lens that makes the light from the light source parallel light, and a second lens that collects the light made parallel by the first lens onto the incident end surface of the optical integrator. ,
The illumination optical system according to claim 1 or 2 , wherein the optical filter is arranged between the first lens and the second lens. It also has a measuring unit that measures the illuminance distribution on the illuminated surface.
The illumination optical system according to any one of claims 1 to 3 , wherein the position of the optical filter is changed based on the illuminance distribution measured by the measuring unit. Further having a control unit for controlling the drive of the optical filter,
The illumination according to claim 4 , wherein the control unit feedback-controls the drive of the optical filter so that the illuminance unevenness calculated from the illuminance distribution measured by the measurement unit is within an allowable range. Optical system. Wherein the optical integrator is arranged between the surface to be illuminated, further comprising a second relay optical system for guiding light from the exit end surface of said optical integrator to said surface to be illuminated,
The second relay optical system is a third lens that makes light from the emission end surface of the optical integrator parallel light, and is a third lens configured to be movable in the optical axis direction of the second relay optical system. Including
Wherein the control unit is further to claim 5, characterized in that the uneven illuminance is calculated from the illuminance distribution measured by said measuring unit performs feedback control of the drive of the third lens to fall within the permissible range The illumination optical system described. The plurality of first regions are regions in which light from the plurality of first regions is reflected by the inner surface of the rod-type optical integrator to form an image on the injection end surface of the rod-type optical integrator. The illumination optical system according to any one of claims 1 to 6. Among the plurality of first regions, the region in which light from the plurality of first regions is not reflected by the inner surface of the rod-type optical integrator and forms an image on the injection end surface of the rod-type optical integrator is described. The illumination optical system according to any one of claims 1 to 7, wherein an adjusting unit is not provided. A lithography system that forms the pattern of the original plate on the substrate.
The illumination optical system according to any one of claims 1 to 8 , which illuminates the original plate arranged on the illuminated surface .
A projection optical system that projects the pattern onto the substrate,
A lithographic apparatus characterized by including. A step of forming a pattern on a substrate by using the lithography apparatus according to claim 9 .
The process of processing the substrate on which the pattern is formed in the process and
A method for manufacturing an article, which comprises.

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