JP2006030651A - Manufacturing method for fine pattern, manufacturing method for optical device, and aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that an etching selection ratio is varied in accordance with time to use an etching device though the operation condition of the etching device is always kept constant so that an etching condition can be the same. <P>SOLUTION: In the forming method for the fine pattern, a substrate to which resist is applied is exposed by using a plurality of gray scale masks, the exposed resist is developed, and the shape of the resist is transferred to the substrate. Then, at least one of a plurality of gray scale masks is the one whose transmittance distribution is set in accordance with the change of the selection ratio of the resist to the substrate in the case of transferring the shape of the resist to the substrate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, a resist is applied on a substrate, the resist is exposed to light using a gray scale mask and developed, and then the resist and the substrate are etched to remove the resist, and the resist The present invention relates to a method of manufacturing a substrate or a microlens having a predetermined pattern shape on the surface by transferring a pattern formed by development to the substrate, or an exposure apparatus using the microlens.

  In recent years, fine optical elements have been manufactured by a photolithography process and an etching process using a gray scale mask. For example, according to the disclosure of JP-A-8-504515, a mask having a gray scale is prepared according to the shape of a microlens to be manufactured, and a resist having a predetermined thickness is applied. Prepare a quartz substrate. Next, the mask and the quartz substrate are set in an exposure apparatus. Then, the transmitted light of the mask is projected onto the quartz substrate for a predetermined time. Thereafter, the resist applied to the quartz substrate is developed, and the shape of the developed resist is transferred to the quartz substrate. Through such a process, the microlens array is manufactured.

When transferring the resist shape onto the quartz substrate, reactive ion etching or ion milling is used.
Japanese National Patent Publication No. 8-504515

    By the way, reactive ion etching and ion milling techniques have different etching rates depending on the material. The ratio of the etching rates of different materials is called the etching selectivity. Depending on the etching selectivity, the shape transferred to the quartz substrate differs from the developed shape of the resist. Furthermore, according to the knowledge of the present inventors, it is known that the etching selectivity changes depending on the resist shape.

  Therefore, in order to manufacture a substrate having a desired shape, a shape that changes due to etching is predicted in advance, and the shape that changes due to etching is taken into consideration, and then the shape of the resist is set. In reality, since the resist shape is determined by the transmitted light distribution of the gray scale mask, the etching selectivity is taken into consideration when designing the mask pattern of the gray scale mask.

  However, although the operating conditions of the etching apparatus are always constant so that the etching conditions are the same, the etching selectivity varies depending on the time during which the etching apparatus is used.

Therefore, it was decided to solve the problem by the following means.
In the first aspect of the present invention, a substrate coated with a resist is exposed using a plurality of gray scale masks, and after the exposed resist is developed, a fine pattern is formed to transfer the shape of the resist to the substrate. In the method, at least one of the plurality of gray scale masks has a transmittance distribution set in accordance with a change in a selection ratio between the resist and the substrate when the resist shape is transferred to the substrate. It is a gray scale mask.

The second aspect of the present invention is the first aspect, wherein the selection ratio is a ratio obtained for each position of a fine pattern to be formed.
Further, the third aspect of the present invention is the second aspect, wherein the fine pattern to be formed has a rotationally symmetric shape, and the selection ratio is determined from each of the symmetry pattern to the peripheral part of the fine pattern to be formed. It is characterized in that the selection ratio at the position is acquired and set as the selection ratio at each position of the fine pattern to be formed.

The fourth aspect of the present invention is the second aspect or the third aspect, wherein the fine pattern to be formed is a pattern having a repetitive shape.
According to a fifth aspect of the present invention, in the method for manufacturing an optical element, a main gray is formed in consideration of the step of applying a resist to a substrate, at least the selectivity between the substrate and the resist, and the shape of the optical element. A step of manufacturing a scale mask, a step of exposing a resist applied to the substrate by the main gray scale mask, a step of developing the exposed resist, and a step of etching the substrate together with the developed resist Comparing the shape of the substrate after the etching with the shape of the optical element, manufacturing a correction gray scale mask, applying a resist to the substrate again, exposure with the main gray scale mask, and the correction After exposure with a gray scale mask and developing the resist, the substrate is etched together with the resist. Characterized in that it comprises a that step.

  The sixth aspect of the present invention is the fifth aspect, wherein the optical element has a symmetrical shape, and in the step of manufacturing the correction grayscale mask, from the center of symmetry of the optical element to the periphery. The correction grayscale mask is manufactured based on the selection ratio obtained at each position and based on the acquired selection ratio and the selection ratio considered in manufacturing the main grayscale mask.

  The seventh aspect of the present invention is the fifth or sixth aspect, wherein the main grayscale mask and the correction grayscale mask have a pattern corresponding to a lens array composed of a plurality of lenses. Features.

  According to an eighth aspect of the present invention, there is provided an exposure apparatus having an optical system provided with the microlens array manufactured in the seventh aspect.

  According to the present invention, a microlens having a desired shape can be manufactured even if the etching conditions cannot be accurately reproduced for each manufacturing rod in the etching process.

Next, embodiments of the present invention will be described with reference to the drawings. A method of manufacturing a microlens array in the embodiment of the present invention will be described.
The process of the microlens array is shown in FIG. FIG. 2 shows the cross-sectional shapes of the resist and the substrate for the process shown in FIG. The method of manufacturing the microlens array in the present embodiment sets the grayscale pattern of the mask according to the shape of the designed microlens and the etching selectivity, and the step of manufacturing the main grayscale mask (S001), An exposure process (S002) for projecting and exposing a resist-coated quartz substrate using a main grayscale mask, a developing process (S003) for developing the resist, and an etching process (S004) for etching the resist and the quartz substrate The method includes an evaluation step (S005) for evaluating the shape of the quartz substrate and a selectivity correction mask manufacturing step (S006).

  First, in the main gray scale mask manufacturing step (S001), the shape of the resist to be manufactured is set based on the lens shape to be manufactured and the etching selectivity. By the way, it has been found by the efforts of the inventors that the etching selectivity varies depending on the shape in addition to the characteristics of the etching apparatus and the etching conditions. The details are as disclosed in Japanese Patent Application No. 2003-393846 (the filing date is November 25, 2003). For example, FIG. 3 shows an etching selectivity when manufacturing a microlens having a radius of curvature of 1455 μm, an effective diameter of 600 μm, and a height of 43 μm. As shown in FIG. 3, the etching selection ratio changes according to the distance from the rotationally symmetric center of the lens. When the etching selectivity varies depending on each lens position, it is very difficult to control the etching selectivity to be the same at any location by changing the etching conditions.

  Therefore, in this embodiment, based on the difference in etching selectivity depending on the position, the shape after development of the resist is determined in consideration of the difference between the shape after development of the resist and the shape after shape transfer to the quartz substrate. The gray scale pattern and the exposure time are determined so that the determined shape of the resist after development can be formed.

When the gray scale pattern is determined in this way, the main gray scale mask 1 having a plurality of patterns as shown in FIG. 4A is manufactured.
In manufacturing the main gray scale mask 1, a chromium film is first formed on a glass substrate for a mask, and an opening 101 corresponding to the gray scale pattern is formed at a predetermined size at each position. The opening is preferably formed by a photolithography process.

  4A is a diagram showing a schematic plane of the gray scale mask 1, and FIG. 4B is obtained by developing after exposure for a predetermined time using the gray scale mask 1 of FIG. The distribution of residual film thickness of the resist is shown. Note that the pattern shown in FIG. 4A is illustrated with only a pattern corresponding to one microlens, and the grayscale mask 1 actually used has a two-dimensional pattern as shown in FIG. Are arranged.

  A method of making a gray scale mask in which the same pattern is two-dimensionally arranged is as follows. A mask having a pattern corresponding to one microlens is manufactured in advance using a laser plotter or an electron beam drawing apparatus. By using the mask, the projection exposure apparatus is projected and exposed on the mask substrate while performing a step-and-repeat operation, and a plurality of the same gray scale patterns can be formed on the main gray scale mask substrate.

  Note that the dimension of the mask pattern having a pattern corresponding to one microlens at first is the reduction ratio of the projection exposure apparatus used when the main grayscale mask 1 is manufactured and the exposure process performed thereafter (S002). It is necessary to determine in consideration of the reduction ratio of the projection exposure apparatus used in (1).

  Next, an exposure step (S002) is performed using the main grayscale mask 1 manufactured in the previous step. FIG. 2 is a diagram showing how the microlens array after the exposure process is manufactured. In this exposure process, as shown in FIG. 2A, the quartz substrate 3 coated with the resist 4 is applied to the quartz substrate 3 as shown in FIG. The projection exposure apparatus projects and exposes the image of the main grayscale mask 1. The exposure time at that time is the same as the time set at the time of manufacturing the main gray scale mask. When a plurality of types of main gray scale masks 1 are used, exposure is sequentially performed before developing the resist. Originally, the projection exposure optical system is disposed between the main grayscale mask 1 and the quartz substrate 3 coated with the resist 4, but this portion is omitted in FIG.

Next, a developing step (S003) for developing the exposed resist is performed. In the developing process, the film is immersed in the developer, and a predetermined shape appears on the surface of the resist 4 as shown in FIG.
Then, the etching process (S004) is performed in a state where the developed resist 4 is provided on the surface of the substrate 3. The quartz substrate 3 having a three-dimensional shape appearing on the surface of the resist 4 by development is placed on an ICP apparatus (inductively coupled plasma etching apparatus), and the quartz substrate 3 is etched together with the resist 4. By this etching, the shape of the resist 4 is transferred to the quartz substrate 3 according to the etching selectivity as shown in FIG. By the way, this ICP apparatus etches the developed resist 4 and the quartz substrate 3 while introducing CHF ₃ , Ar, and O ₂ gas into a vacuum vessel at a predetermined ratio and discharging with a set power. . Thus, when the etching is completed, a predetermined microlens appears on the substrate.

  Next, an evaluation step (S005), which is a step of evaluating the shape of the microlens, is performed. In this evaluation step, it is evaluated whether or not the shape formed on the quartz substrate is a predetermined shape. If the shape is good, the microlens array is shipped. Then, the same steps are repeated again from the exposure steps (S002) to (S005), and microlens arrays having a predetermined shape are sequentially manufactured.

  In the evaluation step (S005), when the evaluation of the shape of the microlens is different from the predetermined shape, the cause of the difference in shape is determined. As a result, when a change is recognized in the etching selection ratio, a manufacturing process (S006) of the selection ratio change correction mask is performed.

  By the way, according to the knowledge of the present inventors, it was found that the shape of the microlens is different from the predetermined shape as the number of microlens arrays manufactured increases. The reason is that the etching selectivity changes differently at each position on the microlens.

  Therefore, the present inventors have selected a gray scale pattern as shown in FIG. 4C when a change in the etching selection ratio that causes a phenomenon that the height of the manufactured lens is lowered occurs. By manufacturing the ratio change correction mask 2 and using the mask 2 and the main grayscale mask 1 during the exposure process, a microlens having a predetermined shape is manufactured without remaking the previously manufactured main grayscale mask 1. be able to.

  Next, the selection ratio change correction mask 2 will be described. As shown in FIG. 4C, the selection ratio change correction mask 2 is a mask having a plurality of openings 201 like the gray scale mask 1. The opening 21 formed in the selection ratio change correction mask 2 has a size set in accordance with a change in the etching selection ratio at a predetermined position. However, the dimensional accuracy of the opening may be worse than that of the main gray scale mask 1 because the shape ratio error is enlarged to produce the selection ratio change correction mask 2 and the exposure time is shortened accordingly.

  The selection ratio change correction mask 2 is designed as follows, for example. The etching selection ratio shown in FIG. 3 is such that when x is a radial distance from the center of the microlens, the selection ratio at each position is substantially on the straight line 0.000873x + 1.482 except for the vicinity of the center and the outer periphery. To do. Based on this, the main gray scale mask 1 is usually designed, but on the other hand, the selection ratio changes for each position as the ICP device becomes dirty or the internal environment of the vacuum vessel changes. As a result, in the example we performed, the etching selectivity was 0.000673 × + 1.4. Taking the position at a radius of 150 μm from the center as an example, the etching selectivity changed from 1.613 to 1.501.

  When the etching selectivity changes, the shape error has the distribution shown in FIG. FIG. 5 is a diagram in which the shape error caused by the change in the selection ratio is plotted for each position in the radial direction from the center of the microlens.

  In the manufacturing method of the microlens array in the embodiment of the present invention, the etching selection ratio is determined from the generated shape error, and the selection ratio change correction mask is designed based on the determined selection ratio.

  When the etching selectivity changes from 0.000873x + 1.482 to 0.000673x + 1.4 as in this embodiment, the selectivity changing mask 2 has an aperture ratio distribution as shown in FIG. Set the size of the opening at each position. FIG. 6 is a graph showing the aperture ratio of the selection ratio change correcting mask for each distance from the lens center. In this embodiment, since the maximum correction amount is 4.7 μm, the exposure time of the selection ratio change correction mask is set to 100 ms in view of the resist sensitivity and the maximum aperture ratio of the selection ratio change correction mask.

  By the way, the exposure time set for the selection ratio change correction mask 2 is also set to be much shorter than the exposure time when the main grayscale mask 1 is used. This is because the thickness of the resist remaining film after development has an inversely proportional relationship to the product of the exposure time and the aperture ratio. Therefore, when the exposure time is short, the change in the thickness of the resist remaining film due to the change in the size of the opening is small as compared with the exposure time set in the main grayscale mask 1, and therefore the selection ratio change correction mask 2. The tolerance of the opening dimension is also large compared to the gray scale described above. The selection ratio change correction mask 2 is easier to manufacture than the main grayscale mask 1 and is simpler than remanufacturing the main grayscale mask 1 every time the etching selection ratio changes.

  In particular, when the aperture ratio is 15% or less, in order to reduce the shape tolerance to about 10%, the tolerance of the opening dimension of the main gray scale mask 1 is on the order of several nm. However, it is sufficient that the tolerance of the selection ratio change correction mask 2 is larger than that. If higher accuracy is required, the minimum aperture ratio of the selection ratio change correction mask is added by 15%. Therefore, the selection ratio change correction mask 2 has a minimum aperture ratio of 15% and a maximum of about 70%. For this reason, the minimum opening size is also increased, and the allowable error is also determined by a predetermined ratio to the size, so that the allowable error of the opening having the minimum opening size is also increased.

  Thus, the manufactured selective ratio change correction mask 2 is used in the exposure step (S002) as shown in FIG. First, exposure using a selective ratio change correction mask 2 is performed on a quartz substrate coated with the same resist as that described above. This exposure is also performed by the projection exposure apparatus as described in the above description. Subsequently, exposure using the main gray scale mask 1 is also performed. In the embodiment of the present invention, the exposure using the selection ratio change correction mask 2 having a short set exposure time is performed first. By first performing exposure using a mask having a short set exposure time, it was possible to prevent the actual resist sensitivity from changing significantly compared to the set resist sensitivity during the subsequent exposure. Therefore, sufficient shape accuracy can be obtained with a predetermined exposure time. In the subsequent steps, as described above, the development step (S003) to the evaluation step (S005) are similarly performed.

  When the etching selection ratio changes again, the selection ratio change correction mask manufacturing process (S006) is performed. At that time, a new selective ratio change correction mask is manufactured again depending on how much the current selective ratio has changed with respect to the etching selective ratio set in the gray scale mask 1.

  As described above, according to the method for manufacturing a microlens array according to the embodiment of the present invention, many microlens arrays with good shape accuracy can be manufactured without remanufacturing the gray scale mask 1.

Moreover, there is no restriction | limiting in the shape of a microlens in the application range of the manufacturing method of this invention. For example, a cylindrical lens array or an optical element array having a free-form surface may be used.
When manufacturing the cylindrical lens array, it is necessary to provide a pattern corresponding to the shape of one lens in the main grayscale mask or the selection ratio correction mask in the direction having the curvature, but in the direction having no curvature, It is not necessary to provide a pattern corresponding to the pattern for one lens. A cylindrical lens can be manufactured by performing exposure while joining exposure regions by a step-and-repeat method in an exposure process in a direction having no curvature.

Alternatively, the substrate on which the microlens is manufactured is not limited to quartz but may be fluorite. What is necessary is just to apply by changing etching gas suitably with the material of a board | substrate.
Furthermore, the manufacturing method of the present invention may be applied when manufacturing the microlens array on both sides of the substrate.

In particular, by manufacturing a cylindrical lens array in which the arrangement directions are orthogonal to each other on opposite surfaces of the same position substrate, a pseudo-lens substitute can be obtained.
By the way, an optical apparatus using the cylindrical lens array according to the manufacturing method of the present invention will be described.

  As an example of this optical apparatus, a reduced projection exposure apparatus used for semiconductor manufacturing will be described as an example. In particular, the reduction projection exposure apparatus according to an example of the present invention can collect light from a light source in a predetermined space with a high accuracy cylindrical lens array, so that light use efficiency of the light source is high and high processing capability is exhibited. I was able to.

Next, the reduced projection exposure apparatus will be described with reference to a schematic configuration diagram.
FIG. 7 shows an outline of the optical system of the reduction projection exposure apparatus according to the embodiment of the present invention. In FIG. 7, the Z axis is along the normal direction of the wafer W coated with resist, the Y axis is parallel to the plane of FIG. 7 in the wafer plane, and is perpendicular to the plane of FIG. 7 in the wafer plane. The X axis is set for each direction. In FIG. 7, the illumination optical device is set to perform annular illumination.

  The reduced projection exposure apparatus of FIG. 7 uses, as the light source 11 for supplying exposure light (illumination light), for example, a KrF excimer laser light source that supplies light with a wavelength of 248 nm or an ArF excimer laser light source that supplies light with a wavelength of 193 nm. It has. A substantially parallel light beam emitted from the light source 11 along the Z direction has a rectangular cross section elongated along the X direction, and enters a beam expander 12 including a pair of lenses 12a and 12b. The light beam is shaped into a light beam having a rectangular cross section.

  The substantially parallel light beam that has passed through the beam expander 12 as a shaping optical system is deflected in the Y direction by the bending mirror 13 and then enters the afocal zoom lens 15 through the diffractive optical element 14. In general, a diffractive optical element is formed by forming a step having a pitch of about the wavelength of exposure light (illumination light) on a glass substrate, and has a function of diffracting an incident beam to a desired angle. Specifically, the diffractive optical element 14 has a function of forming a circular light intensity distribution in the far field (or Fraunhofer diffraction region) when a parallel light beam having a rectangular cross section is incident. Therefore, the light beam passing through the diffractive optical element 14 forms a circular light intensity distribution, that is, a light beam having a circular cross section at the pupil position of the afocal zoom lens 15.

  The afocal zoom lens 15 is configured so that the magnification can be continuously changed within a predetermined range while maintaining an afocal system (non-focus optical system). The light beam that has passed through the afocal zoom lens 15 enters the diffractive optical element 16 for annular illumination. The afocal zoom lens 15 optically substantially conjugates the divergence origin of the diffractive optical element 14 and the diffractive surface of the diffractive optical element 16. The numerical aperture of the light beam condensed on one point of the diffractive surface of the diffractive optical element 16 or a surface in the vicinity thereof changes depending on the magnification of the afocal zoom lens 15.

The diffractive optical element 16 for annular illumination has a function of forming a ring-shaped light intensity distribution in the far field when a parallel light beam is incident.
The light beam that has passed through the diffractive optical element 16 enters the zoom lens 17. A micro fly's eye lens 18 is provided in the vicinity of the rear focal plane of the zoom lens 17. The micro fly's eye lens 18 includes, in order from the light source side, a first fly eye member 18a and a second fly eye member 18b made of a micro cylindrical lens manufactured by the manufacturing method of the present invention.

  The incident surface of the micro fly's eye lens (or fly eye lens) 18 (that is, the incident surface of the first fly's eye member 18a) is positioned. The micro fly's eye lens 18 functions as an optical integrator that forms a large number of light sources based on incident light beams.

  As described above, the light beam from the circular light intensity distribution formed at the pupil position of the afocal zoom lens 15 via the diffractive optical element 14 is emitted from the afocal zoom lens 15 and then has various angular components. Is incident on the diffractive optical element 16. That is, the diffractive optical element 16 constitutes an optical integrator having an angle beam forming function. On the other hand, the diffractive optical element 16 has a function of forming a ring-shaped light intensity distribution in the far field when a parallel light beam is incident. Therefore, the light beam that has passed through the diffractive optical element 16 forms an annular illumination field centered on the optical axis AX, for example, on the rear focal plane of the zoom lens 17 (and hence on the incident surface of the micro fly's eye lens 18). .

  The outer diameter of the annular illumination field formed on the incident surface of the micro fly's eye lens 18 changes depending on the focal length of the zoom lens 17. Thus, the zoom lens 17 substantially connects the diffractive optical element 16 and the incident surface of the micro fly's eye lens 18 in a Fourier transform relationship. The light beam incident on the micro fly's eye lens 18 is two-dimensionally divided, and a large number of ring-shaped zones that are the same as the illumination field formed by the light beam incident on the micro fly's eye lens 18 on the rear focal plane of the micro fly eye lens 18. A light source (hereinafter referred to as “secondary light source”) is formed.

  The light beam from the annular secondary light source formed on the rear focal plane of the micro fly's eye lens 18 is subjected to the light collecting action of the condenser optical system 19 and then superimposed on the mask M on which a predetermined pattern is formed. To illuminate. The light beam that has passed through the pattern of the mask M forms an image of the mask pattern on the wafer W coated with the resist via the projection optical system PL. Thus, by performing batch exposure or scan exposure while driving and controlling the wafer W two-dimensionally in a plane (XY plane) orthogonal to the optical axis AX of the projection optical system PL, each exposure region of the wafer W is masked. M patterns are sequentially exposed.

  In addition, the manufacturing method of the microlens array in the present invention is not limited to this, and a shape formed on a quartz substrate, a fluorite substrate, or the like is used as a mold. You may apply to the method of manufacturing. In this method, the cost per set of microlens arrays can be reduced. Furthermore, the shape formed on the quartz substrate or the fluorite substrate is used as a mother mold, and a film necessary for forming plating on the surface of the mother mold is formed by vapor deposition, and a plating layer is further formed. It is also possible to obtain a mold and manufacture a microlens array having a shape that becomes an inverted shape of the mold using a resin or the like.

It is a flowchart which shows the manufacturing process of the micro lens array which is embodiment of this invention. It is a figure which shows the cross-sectional shape of the board | substrate and resist in each process of the manufacturing method in embodiment of this invention. In the manufacturing method of the microlens array in embodiment of this invention, it is the figure which showed the etching selectivity for every distance from the center of a microlens. In the method of manufacturing a microlens array in the embodiment of the present invention, a schematic configuration diagram of a grayscale mask to be used (a) obtained as a result of exposure with a grayscale mask (b) a residual film distribution of a resist after development, and It is a schematic block diagram of a selection ratio change correction mask. In the manufacturing method of the microlens array which is embodiment of this invention, it is the figure which showed error distribution of the microlens manufactured without using a selection ratio change correction mask after an etching selection ratio change. It is an aperture ratio distribution of the selection ratio change correction mask used in the manufacturing method of the microlens array manufacturing method according to the embodiment of the present invention. It is a figure which shows the outline | summary of the optical system of the reduction projection exposure apparatus which is an example of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Gray scale mask, 2 ... Selection ratio change correction mask, 101, 201 ... Aperture, 3 ... Quartz substrate, 4 ... Resist, 11 ... Light source, 12 ... Beam expander, 13 ... Folding mirror, 14, 16 ... Diffractive optical element 15 ... afocal zoom lens, 17 ... zoom lens, 18 ... micro fly eye, 19 ... condenser optical system

Claims (8)

In a method for forming a fine pattern in which a resist-coated substrate is exposed using a plurality of gray scale masks, and after developing the exposed resist, the shape of the resist is transferred to the substrate.
At least one of the plurality of gray scale masks is a gray scale mask in which a transmittance distribution is set according to a change in a selection ratio between the resist and the substrate when the resist shape is transferred to the substrate. A method for forming a fine pattern, characterized in that   The method for forming a fine pattern, wherein the selection ratio is a ratio obtained for each position of the fine pattern to be formed. The fine pattern to be formed has a rotationally symmetric shape,
3. The selection ratio according to claim 2, wherein the selection ratio at each position from the center of symmetry to the periphery of the fine pattern to be formed is obtained as a selection ratio at each position of the fine pattern to be formed. The formation method of the fine pattern of description.   The method for forming a fine pattern according to claim 2 or 3, wherein the fine pattern to be formed is a pattern having a repetitive shape. In the method of manufacturing an optical element,
Applying a resist to the substrate;
In consideration of at least the selectivity between the substrate and the resist and the shape of the optical element, a step of manufacturing a main grayscale mask;
Exposing the resist applied to the substrate with the main grayscale mask;
Developing the exposed resist;
Etching the substrate with the developed resist;
Comparing the shape of the substrate after the etching with the shape of the optical element to produce a corrected grayscale mask;
An optical element comprising: applying a resist to the substrate again, performing exposure using the main gray scale mask and exposure using the correction gray scale mask, and etching the substrate together with the resist after developing the resist. Manufacturing method. In the manufacturing method of the optical element according to claim 5, the optical element is symmetrical.
In the step of manufacturing the corrected grayscale mask, the selection ratio at each position from the symmetry center to the periphery of the optical element is acquired, and is taken into consideration when the acquired selection ratio and the main grayscale mask are manufactured. An optical element manufacturing method, wherein the correction grayscale mask is manufactured based on a selection ratio. In the manufacturing method of the optical element according to claim 5 or 6,
The method of manufacturing an optical element, wherein the main gray scale mask and the correction gray scale mask have a pattern corresponding to a lens array including a plurality of lenses. An illumination optical system including a microlens array manufactured by the method for manufacturing an optical element according to claim 7, and a projection optical system that forms a projection image of a mask irradiated with light output from the illumination optical system An exposure apparatus comprising: