JP2010066727A - Manufacturing method of microlens array and manufacturing method of photoelectric conversion device - Google Patents

Abstract

A microlens array in which a plurality of microlenses each having a spherical surface on the entire surface is arranged even when the gap between adjacent microlenses is reduced.
A method of manufacturing a microlens array using an exposure apparatus, the method comprising: applying a photosensitive resin on a substrate on which a plurality of pixel regions are arranged; and a plurality of pixel regions in the photosensitive resin. A first exposure step of exposing the photosensitive resin using a first original plate for forming a distribution of exposure amount according to the shape of each microlens, and developing the exposed photosensitive resin The pattern is exposed using a second original plate for shielding the inner part of the pixel area and exposing the outer part in each of the plurality of pixel areas after the developing process for forming the pattern and after the developing process. A second exposure step and a heating step of forming a plurality of microlenses in a plurality of pixel regions by heating the pattern after the second exposure step.
[Selection] Figure 2

Description

  The present invention relates to a method for manufacturing a microlens array and a method for manufacturing a photoelectric conversion device.

  In an imaging system such as a video camera or a digital still camera, a photoelectric conversion device such as a CCD image sensor or a CMOS sensor is used. The photoelectric conversion device includes a pixel array in which a plurality of pixels are arrayed. Each of the plurality of pixels includes a light receiving unit (photoelectric conversion element) and a microlens that collects light on the light receiving unit.

  In Patent Document 1, as shown in FIG. 2 of Patent Document 1, a resist layer 32 is applied on a semiconductor substrate 12 via a fixed layer 30 and patterned using a photomask 34, followed by thermal deformation. It is described that the microlens 28 is formed by the above.

  In recent years, with the demand for photoelectric conversion devices to generate high-resolution image signals, the size of each pixel in the pixel array has been reduced, and the light receiving area of the light receiving unit in each pixel tends to decrease. is there. Therefore, it is required for the microlens of each pixel to efficiently incorporate light into the light receiving unit.

  In order to satisfy this requirement, it is conceivable to improve the sensitivity by forming the above-described microlens up to the vicinity of the boundary between pixels and increasing the efficiency of capturing light into the microlens. For this purpose, it is necessary to narrow the gap between the microlenses of adjacent pixels as much as possible.

On the other hand, in Patent Document 2, as shown in FIG. 1 of Patent Document 2, a positive photosensitive lens material is spin-coated on a semiconductor substrate 10 through a planarizing layer 16 and a color filter layer 18. A photosensitive lens material layer 20 is formed. As shown in FIG. 2A of Patent Document 2, the photosensitive lens material layer 20 uses a photomask 24 composed of a halftone mask having a pattern gradation that allows microlenses to be formed. And exposed. Thereafter, as shown in FIG. 2B of Patent Document 2, after the exposed photosensitive lens material layer 20 is developed, the surface is subjected to light irradiation treatment to be temporarily cured, and further subjected to heat treatment. To cure. Thereby, according to patent document 2, it is supposed that the curvature of an outer surface can be made equal to each microlens from each vertex to each base end.
Japanese Patent Laid-Open No. 3-152972 JP 2007-316153 A

  In Patent Document 2, as shown in FIG. 3A of Patent Document 2, by adjusting the number of dots having a dimension equal to or smaller than the wavelength of the exposure light in the photomask 24, gradations are concentrically formed. It is described to change sequentially.

  When the present inventor exposed the photosensitive lens material layer 20 using such a photomask 24, the outer portion of the pixel deviates from the ideal spherical surface in the microlens pattern obtained by subsequent development. I found out that it would be in shape. In addition, since the inventor performs a light irradiation process in the developed state to temporarily cure the microlens pattern, the outer portion of the pixel is ideal on the final microlens surface as well. It was also found that there is a high possibility of curing in a shape deviating from a spherical surface.

  An object of the present invention is to obtain a microlens array in which a plurality of microlenses each having a spherical surface on the entire surface are arranged even when a gap between adjacent microlenses is reduced.

  A microlens array manufacturing method according to a first aspect of the present invention is a microlens array manufacturing method for manufacturing a microlens array by using an exposure apparatus, wherein the microlens array is photosensitive on a substrate on which a plurality of pixel regions are arranged. Applying the photosensitive resin using a first original plate for forming a distribution of exposure amount according to the shape of the microlens in each of the plurality of pixel regions in the photosensitive resin; A first exposure step of exposing, a developing step of developing a pattern by developing the exposed photosensitive resin, and an inner side of the pixel region in each of the plurality of pixel regions after the developing step. A second exposure step of exposing the pattern using a second original plate for shielding a portion of the mask and exposing an outer portion; and after the second exposure step, the pattern By heating, characterized by comprising a heating step of forming a plurality of micro-lenses to said plurality of pixel areas.

  A method for manufacturing a photoelectric conversion device according to a second aspect of the present invention is a method for manufacturing a photoelectric conversion device having a substrate on which a plurality of pixel regions are arranged, wherein photoelectric conversion is performed on each of the plurality of pixel regions on the substrate. Forming a portion, forming a photosensitive resin on the substrate, and forming a distribution of exposure amount according to the shape of the microlens in each of the plurality of pixel regions in the photosensitive resin. A first exposure step of exposing the photosensitive resin using a first original plate, a development step of developing a pattern by developing the exposed photosensitive resin, and after the development step, A second exposure that exposes the pattern using a second original plate that includes a pattern that shields an inner portion of the pixel region and exposes an outer portion corresponding to each of the plurality of pixel regions. And extent, after the second exposure step, by heating the pattern, characterized by comprising a heating step of forming a plurality of micro-lenses to said plurality of pixel areas.

  According to the present invention, a microlens array in which a plurality of microlenses each having a spherical surface on the entire surface can be obtained even when the gap between adjacent microlenses is reduced.

  In this specification, “pixel” is used as a concept including not only a photoelectric conversion unit (for example, a photodiode) but also a microlens. The “pixel region” means a three-dimensional region where a pixel is to be formed. In addition, forming a predetermined layer “on” includes not only the case where the predetermined layer is directly formed above, but also the case where the predetermined layer is formed on another layer.

  In the drawings, the microlens and the photomask to be formed are shown at the same scale for the sake of explanation. However, in actuality, the pattern on the photomask is reduced at a predetermined magnification by reduced projection exposure (photosensitive). To be transferred). For example, in a photomask, a pattern having a dimension four or five times as large as a pattern actually formed is formed of chromium or the like. The pattern on the photomask is reduced to ¼ or に よ り by reduction projection exposure and transferred onto a semiconductor substrate (to a photosensitive resist). For this reduced projection exposure, an exposure device (not shown) such as a stepper or a scanner is used.

  The problem of the present invention will be described in detail with reference to the drawings.

  First, problems when the reflow method is set so as to reduce the gap between the microlenses will be described with reference to FIGS. FIG. 4 is a process flow diagram illustrating a flow of processes for manufacturing the photoelectric conversion device 100 using the reflow method. FIG. 5 is a diagram illustrating a plurality of pixel regions. FIG. 6 is a process cross-sectional view illustrating a flow of a process for manufacturing the photoelectric conversion device 100 using the reflow method.

  In the step of S11 shown in FIG. 4, the photoelectric conversion unit 1 is formed in each of the plurality of pixel regions PA11 to PA33 (see FIG. 5) in the semiconductor substrate SB (formation step, see FIG. 6A). Here, as shown in FIG. 5, a plurality of pixel regions PA11 to PA33 are arranged on the semiconductor substrate SB. FIG. 6 shows a cross section in the pixel areas PA11 to PA13. Hereinafter, the pixel areas PA11 to PA13 will be exemplarily described.

  Next, a photosensitive photoresist 6 (photosensitive resin) is applied on the semiconductor substrate SB (application process, see FIG. 6A).

  Specifically, after the light shielding portion 2, the planarizing layer 3, the color filters 4a to 4c, and the planarizing layer 5 are formed on the semiconductor substrate SB, the microphotosensitive photoresist 6 is applied to the planarizing layer 5. Apply on top. As the photosensitive photoresist 6, for example, photosensitive photoresist TMR-P10PM 2.1 cp manufactured by Tokyo Ohka Kogyo Co., Ltd. is used. The photosensitive photoresist 6 is applied by spin coating, for example, at a rotation speed of 1000 rpm. Thereafter, baking is performed on a hot plate at 100 ° C. for 2 minutes. The film thickness of the photosensitive photoresist 6 at this time is, for example, 0.4 μm.

  In step S12, the photosensitive photoresist 6 is exposed using a photomask M (see FIG. 6A) having a pattern in which the vicinity of the boundary between the pixel areas PA11 to PA33 is opened. In this photomask M, the widths d1 and d2 of the opening pattern are set to be small so as to reduce the gap between adjacent microlenses in the developed microlens pattern.

  Here, the amount of light irradiation by the exposure apparatus is, for example, 1200 J / m 2.

  In step S13, the exposed photosensitive photoresist 6 is developed. Thereby, the developed pattern 7 is formed (see FIG. 6B). For example, paddle development is performed for 30 to 60 seconds on the photosensitive photoresist 6 using an alkaline developer (TMAH (tetramethylammonium hydroxide) aqueous solution: solution concentration 2.38 wt%).

  In step S14, the developed pattern 7 is heated and thermally deformed (reflowed) to form a plurality of microlenses 8-11 to 8-13 (see FIG. 6C). Thereby, the photoelectric conversion apparatus 100 is manufactured.

  Here, a variation in the size of the gap between the microlenses due to the exposure process (S12) and the development process (S13), and a variation in the flow amount that is melted and deformed by the heating process (S14) occur. For this reason, the microlenses may be fused after the heat treatment (see FIG. 6C). The fused microlens loses its light condensing function to the photoelectric conversion unit 1 of the fused microlens, so that the effective surface area of the microlens is reduced, and photoelectric conversion from the microlens 8 is performed. There is a possibility that the light collection efficiency to the part 1 is deteriorated.

  Next, a problem in the case of setting to reduce the gap between the microlenses in the technique using the photomask having the gradation pattern will be described with reference to FIGS. FIG. 7 is a process flow diagram showing a flow of a process for manufacturing the photoelectric conversion device 200 using a technique using a photomask having a gradation pattern. FIG. 8 is a process cross-sectional view illustrating a flow of a process for manufacturing the photoelectric conversion device 200 using a technique using a photomask having a gradation pattern. Below, it demonstrates centering on a different point from the manufacturing method shown in FIGS.

  In the step S22 shown in FIG. 7 (first exposure step), a photomask M1 (first original, diagram) including a plurality of dot patterns corresponding to each of the plurality of pixel regions below the resolution limit of the exposure apparatus. 8 (a)), the photosensitive photoresist 6 (photosensitive resin) is exposed. That is, the photomask M1 is a photomask for forming an exposure amount distribution corresponding to the shape of the microlens in each of a plurality of pixel regions in the photosensitive photoresist 6. Thereby, a latent image is formed on the photosensitive photoresist 6.

  Specifically, the photosensitive photoresist 6 is exposed using a photomask M1 (see FIG. 8A) having a gradation pattern in which the light transmittance decreases concentrically from the periphery to the center in the pixel region. . In the photomask M1, a concentric gradation pattern is formed by adjusting the number of dots having a dimension less than the resolution limit of the exposure apparatus. For example, by adjusting the number of fine dots that are not resolved at 365 nm, which is the exposure wavelength of the exposure apparatus, the photomask M1 can have concentric gradations with different light transmittances concentrically. In the photomask M1 used in this embodiment, the number of white dots is reduced (or the number of black dots is increased) as it approaches the line passing through the center of the light receiving unit. The light transmittance is reduced.

  In step S23 (development step), the developed pattern is formed by developing the latent image.

  Specifically, the exposed photosensitive photoresist 6 is developed. Thereby, the latent image in the photosensitive photoresist 6 is developed, and developed patterns 207-11 to 207-12 are formed (see FIG. 8B).

  In step S24, the developed patterns 207-11 to 207-12 are temporarily cured by performing a light irradiation process on the developed patterns 207-11 to 207-12. Thereafter, the temporarily cured developed patterns 207-11 to 207-12 are heated and cured to form a plurality of microlenses 208-11, 208-12, and 208-13. Thereby, the photoelectric conversion apparatus 200 is manufactured.

  Here, the present inventor has found that the amount of light irradiation on the outer portions OA11 to OA13 (see FIG. 5) in each of the pixel regions PA11 to PA13 may be excessive. In this case, on the surface of the microlens actually completed, the outer portion of each of the pixel areas PA11 to PA13 does not have an ideal spherical shape, but is a concave shape so that the ideal spherical surface approaches the surface of the semiconductor substrate SB. become. The thickness of the outer portions OA11 to OA13 in the pixel areas PA11 to PA13 is, for example, 0 to 0.1 μm.

  As described above, although the gap between the microlenses is zero, the slender shape (recessed shape) in the outer portion of each pixel area PA11 to PA13 of the microlens causes the microlens 10 to the photoelectric conversion unit 1 to move. There is a possibility of deteriorating the light collection efficiency.

  Therefore, the present invention provides a method by which a microlens having a hemispherical spherical surface that has zero gap between the microlenses on the photoelectric conversion device and an ideal lens shape can be easily manufactured. Objective.

  Next, a method for manufacturing the photoelectric conversion device 300 according to the embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a process flow diagram illustrating a method for manufacturing a photoelectric conversion apparatus 300 according to an embodiment of the present invention. FIG. 2 is a process cross-sectional view illustrating the method for manufacturing the photoelectric conversion device 300 according to the embodiment of the present invention. Below, it demonstrates centering on a different point from the manufacturing method shown in FIGS.

  In step S4 (second exposure step) shown in FIG. 1, a photomask M2 (second original plate) is used. The photomask M2 includes patterns corresponding to each of the plurality of pixel regions PA11 to PA13 that shield the inner portions IA11 to IA13 in the pixel regions PA11 to PA13 and expose the outer portions OA11 to OA13. The developed patterns 207-11 to 207-13 are exposed using the photomask M2. As a result, the outer portions OA11 to OA13 in the plurality of pixel areas PA11 to PA13 of the developed patterns 307-11 to 307-13 are cured (see FIG. 2E).

  Specifically, the photomask M2 includes rectangular shielding patterns SP11 to SP13 for shielding the inner portions IA11 to IA13 in the pixel areas PA11 to PA13, corresponding to each of the plurality of pixel areas PA11 to PA13. . The interval between the shielding patterns SP11 to SP13 is, for example, about 3% of the size of each pixel area PA, and is 0.4 μm in actual size, for example.

  Note that when the size of the pixel region is reduced, it is necessary to reduce the interval between the shielding patterns. However, when the interval between the shielding patterns is less than 0.2 μm, a photomask using an electron beam or a laser beam is manufactured. Requires a lot of time and money. For this reason, the interval between the shielding patterns is preferably 0.2 μm or more. For example, when a photomask having a shielding pattern interval of 0.2 μm and a reduction ratio of 4 times is used, the outer portions OA11 to OA13 in the exposed pixel regions PA11 to PA13 are the ends of the pixel regions PA11 to PA13. To a portion having a width of 25 nm.

  On the other hand, in consideration of alignment variations of the exposure apparatus, it is preferable to irradiate light to a region 100 nm from the end of the pixel regions PA11 to PA13. However, if light is irradiated to a region larger than 100 nm from the end of the pixel regions PA11 to PA13, the region that is difficult to be melted is increased. Therefore, the outer portions OA11 to OA13 in the pixel regions PA11 to PA13 are made spherical in the subsequent heating process. It may not be possible.

  Therefore, the outer portions OA11 to OA13 in the pixel regions PA11 to PA13 to be exposed in S4 (second exposure step) are preferably portions having a width of 25 to 100 nm from the ends of the pixel regions PA11 to PA13. .

  Moreover, the exposure light irradiation amount by the exposure apparatus is, for example, 3000 J / m 2, and the wavelength of the exposure light is 365 nm. The exposure amount is preferably 900 J / m 2 or more and 20000 J / m 2 or less. The wavelength of the exposure light may be 172 nm (excimer UV light), 192 nm (ArF laser), and 254 nm (KrF laser).

  In step S5 (heating step), the developed patterns 307-11 to 307-13 are heated to form a plurality of microlenses 308-11 to 308-13 in the plurality of pixel regions PA11 to PA13.

  Specifically, the developed patterns 307-11 to 307-13 are heated at a temperature of 140 ° C to 170 ° C. Thereby, the inner portions IA11 to IA13 in each of the plurality of pixel areas PA11 to PA13 of the developed patterns 307-11 to 307-13 are thermally melted (melting step, see FIG. 2F). For this reason, the inner portions IA11 to IA13 in which the outer portions OA11 to OA13 themselves are not melted in the pixel areas PA11 to PA13 of the developed patterns 307-11 to 307-13 are melted slightly and the outer portions IA11 to IA13 are slightly outer portions. Go to OA11-OA13. Specifically, it flows into the outside portions OA11 to OA13. As a result, the adjacent microlenses 308-11 to 308-13 can be prevented from being thermally welded, and the outer surfaces OA11 to OA13 in the pixel regions PA11 to PA13 have a spherical surface continuous from the inner portions IA11 to IA13. Come to form.

  Here, if the heating temperature of the developed patterns 307-11 to 307-13 is lowered below 140 ° C., there is a possibility that the melting is insufficient and a spherical shape cannot be obtained. When the heating temperature of the developed patterns 307-11 to 307-13 is increased from 170 ° C., the region whose heat resistance has been increased by light irradiation starts to melt, so that the outer portion of the pixel region between adjacent pixel regions Fusion occurs between each other. Therefore, the heating temperature for melting the developed patterns 307-11 to 307-13 is preferably in the range of 140 ° C to 170 ° C.

  Thereafter, the developed patterns 307-11 to 307-13 are heated at a temperature of 180 to 200 ° C. Thus, the developed patterns 307-11 to 307-13 are cured to form a plurality of microlenses 308-11 to 308-13 in the plurality of pixel areas PA11 to PA13 (curing step). Thereby, a microlens array in which a plurality of microlenses each having a spherical surface on the entire surface is arranged is formed.

  Here, when the heating temperature of the developed patterns 307-11 to 307-13 is lowered below 180 ° C., the region whose heat resistance has been increased by the light irradiation starts to melt, so that the outside of the pixel region between the adjacent pixel regions is increased. Fusion of parts occurs. If the heating temperature of the developed patterns 307-11 to 307-13 is increased from 200 ° C., the photosensitive resist may not be sufficiently cured. Therefore, the heating temperature for curing the developed patterns 307-11 to 307-13 is preferably in the range of 180 to 200 ° C.

  In this step, for example, using a hot plate, the developed patterns 307-11 to 307-13 are subjected to a heat treatment at 140 ° C. for 5 minutes and a heat treatment at 200 ° C. for 5 minutes. went.

  Due to the heat treatment at 140 ° C., the inner part of the pixel region not exposed in the step S4 is melted and deformed into a spherical shape determined by the surface tension. At this time, the outer part in the pixel area is hardly thermally deformed and can maintain the state before the heat treatment. It becomes possible to change to.

  Thereafter, the lens material is completely cured by raising the temperature to 200 ° C. and heating. Once the lens melts and changes shape, it is necessary to raise the temperature and then cure, but it has been found that if the temperature range is 180 ° C. or higher, it will cure sufficiently.

  As described above, in the method for manufacturing the photoelectric conversion device according to the present embodiment, the developed pattern that has undergone the development process is exposed again using the photomask having the pattern in which the inner portion of the pixel region is shielded. And after passing through the process which improves the heat resistance of the outer part in a pixel area | region, it heats at the temperature of 140 to 170 degreeC. At this time, since the outer portion of the pixel area exposed again is not melted, the fusion of the microlenses can be reduced. In addition, the inner part of the pixel area is heated and deformed, and flows into the outer part of the pixel area (deformed shape after development), so that the hemispherical shape determined by the surface tension is also applied to the outer part of the pixel area. Can be formed. Furthermore, a photoresist is hardened by heating at the temperature of 180-200 degreeC. By using a developed pattern formed using a photomask M1 having a gradation pattern, the thickness of the outer portion of each pixel region is thin, so that curing by exposure processing is sufficiently possible, and heat treatment It is easy to suppress fusion.

  That is, according to the present embodiment, it is possible to obtain a hemispherical ideal surface shape with no gap between the microlenses and without any drooping. By using this microlens, it is possible to improve the light collection efficiency from the microlens to the photoelectric conversion unit, and it is possible to improve the decrease in device sensitivity due to the recent reduction in pixel size.

  Next, an example of an imaging system to which the photoelectric conversion device of the present invention is applied is shown in FIG.

  As shown in FIG. 3, the imaging system 90 mainly includes an optical system, an imaging device 86, and a signal processing unit. The optical system mainly includes a shutter 91, a lens 92, and a diaphragm 93. The imaging device 86 includes a photoelectric conversion device 300. The signal processing unit mainly includes an imaging signal processing circuit 95, an A / D converter 96, an image signal processing unit 97, a memory unit 87, an external I / F unit 89, a timing generation unit 98, an overall control / calculation unit 99, and a recording. A medium 88 and a recording medium control I / F unit 94 are provided. The signal processing unit may not include the recording medium 88.

  The shutter 91 is provided in front of the lens 92 on the optical path, and controls exposure.

  The lens 92 refracts the incident light and forms an image of the subject on the imaging surface of the photoelectric conversion device 300 of the imaging device 86.

  The diaphragm 93 is provided between the lens 92 and the photoelectric conversion device 300 on the optical path, and adjusts the amount of light guided to the photoelectric conversion device 300 after passing through the lens 92.

  The photoelectric conversion device 300 of the imaging device 86 converts the image of the subject formed on the imaging surface of the photoelectric conversion device 300 into an image signal. The imaging device 86 reads the image signal from the photoelectric conversion device 300 and outputs it.

  The imaging signal processing circuit 95 is connected to the imaging device 86 and processes the image signal output from the imaging device 86.

  The A / D converter 96 is connected to the imaging signal processing circuit 95 and converts the processed image signal (analog signal) output from the imaging signal processing circuit 95 into an image signal (digital signal).

  The image signal processing unit 97 is connected to the A / D converter 96, and performs various kinds of arithmetic processing such as correction on the image signal (digital signal) output from the A / D converter 96 to generate image data. To do. The image data is supplied to the memory unit 87, the external I / F unit 89, the overall control / calculation unit 99, the recording medium control I / F unit 94, and the like.

  The memory unit 87 is connected to the image signal processing unit 97 and stores the image data output from the image signal processing unit 97.

  The external I / F unit 89 is connected to the image signal processing unit 97. Thus, the image data output from the image signal processing unit 97 is transferred to an external device (such as a personal computer) via the external I / F unit 89.

  The timing generation unit 98 is connected to the imaging device 86, the imaging signal processing circuit 95, the A / D converter 96, and the image signal processing unit 97. Thereby, a timing signal is supplied to the imaging device 86, the imaging signal processing circuit 95, the A / D converter 96, and the image signal processing unit 97. The imaging device 86, the imaging signal processing circuit 95, the A / D converter 96, and the image signal processing unit 97 operate in synchronization with the timing signal.

  The overall control / arithmetic unit 99 is connected to the timing generation unit 98, the image signal processing unit 97, and the recording medium control I / F unit 94, and the timing generation unit 98, the image signal processing unit 97, and the recording medium control I / F. The unit 94 is controlled as a whole.

  The recording medium 88 is detachably connected to the recording medium control I / F unit 94. As a result, the image data output from the image signal processing unit 97 is recorded on the recording medium 88 via the recording medium control I / F unit 94.

  With the above configuration, if a good image signal is obtained in the photoelectric conversion device 300, a good image (image data) can be obtained.

The process flow figure showing the manufacturing method of photoelectric conversion device 300 concerning the embodiment of the present invention. Process sectional drawing which shows the manufacturing method of the photoelectric conversion apparatus 300 which concerns on embodiment of this invention. The block diagram of the imaging system to which the photoelectric conversion apparatus which concerns on embodiment of this invention is applied. The figure for demonstrating the subject of this invention. The figure for demonstrating the subject of this invention. The figure for demonstrating the subject of this invention. The figure for demonstrating the subject of this invention. The figure for demonstrating the subject of this invention.

Explanation of symbols

100, 200, 300 Photoelectric conversion device

Claims (4)

A microlens array manufacturing method for manufacturing a microlens array using an exposure apparatus,
A coating step of coating a photosensitive resin on a substrate on which a plurality of pixel regions are arranged;
A first exposure step of exposing the photosensitive resin to each of the plurality of pixel regions in the photosensitive resin using a first original plate for forming a distribution of exposure amount according to a shape of a microlens;
A developing step of forming a pattern by developing the exposed photosensitive resin;
After the developing step, a second exposure step of exposing the pattern using a second original plate for shielding an inner portion of the pixel region and exposing an outer portion of each of the plurality of pixel regions. When,
A heating step of forming a plurality of microlenses in the plurality of pixel regions by heating the pattern after the second exposure step;
A method of manufacturing a microlens array, comprising: 2. The outer portion of each of the plurality of pixel regions exposed in the second exposure step is a portion having a width of 25 to 100 nm from an end of the pixel region. The manufacturing method of the microlens array of description. The heating step includes
A melting step of thermally melting the inner portion of each of the plurality of pixel regions of the pattern by heating the pattern at a temperature of 140 ° C. to 170 ° C .;
After the melting step, the step of curing the pattern by heating the pattern at a temperature of 180 to 200 ° C. to form the plurality of microlenses in the plurality of pixel regions;
The method for producing a microlens array according to claim 1, wherein A method for manufacturing a photoelectric conversion device having a substrate on which a plurality of pixel regions are arranged,
Forming a photoelectric conversion portion in each of the plurality of pixel regions in the substrate;
An application step of applying a photosensitive resin on the substrate;
A first exposure step of exposing the photosensitive resin to each of the plurality of pixel regions in the photosensitive resin using a first original for forming a distribution of exposure amount according to the shape of a microlens;
A developing step of forming a pattern by developing the exposed photosensitive resin;
After the developing step, the pattern is exposed using a second original plate that includes a pattern that shields an inner portion of the pixel region and exposes an outer portion corresponding to each of the plurality of pixel regions. Exposure process,
A heating step of forming a plurality of microlenses in the plurality of pixel regions by heating the pattern after the second exposure step;
A method for manufacturing a photoelectric conversion device, comprising:

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