JP2007316153A - Method of manufacturing microlens for color imaging element and microlens array for color imaging element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a microlens for a color imaging element by which manufacture cost can be reduced without lowering optical performance of the microlens directly formed on a color filter and to provide a microlens array which can sufficiently function between adjoining microlenses. <P>SOLUTION: In the method of manufacturing the microlens for the color imaging element, a color filter layer 18 is formed on a flattening layer 16 formed on a photoelectric conversion element 12 in a semiconductor substrate 10 of the imaging element 14, then a photosensitive lens material layer 20 is formed on the filter layer. The lens material layer is subjected to pattern exposure by using a photomask 24 with controlled transmittance distribution so that microlenses 22g, 22b and 22r may be formed on the corresponding photoelectric conversion element after development and then is subjected to development and hardening to form the microlens on the corresponding photoelectric conversion element. The microlens array 28 containing a plurality of the microlenses is manufactured by the above-mentioned manufacturing method. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a microlens manufacturing method for a color image sensor and a microlens array for a color image sensor.

  In a conventional color imaging device, color filters of a plurality of colors are formed on a plurality of photoelectric conversion elements provided on a semiconductor substrate, adjacent to each other using a photolithography technique, without a gap. The color filter has a thickness of approximately 1 μm. Color filters include those that are colorless.

  In recent years, the number of pixels of an image sensor has been increased, and in recent years, the number of pixels has reached several million. In addition, as the number of pixels increases, the ratio of the area occupied by various wirings and electronic circuits for operating each pixel in each pixel increases, and the photoelectric conversion element actually receives light in each pixel at present. Therefore, the ratio of the area that can be used (opening ratio) is about 20 to 40%.

  This means that the photosensitivity of the image sensor is lowered.

  In order to improve the photosensitivity of the image pickup device, it is possible to form a microlens on the color filter corresponding to the photoelectric conversion device, as disclosed in JP-A-59-122193 (Patent Document 1) and JP-A-2005-294467. This is disclosed in Japanese Patent Laid-Open No. 2004-145319 and Japanese Patent Laid-Open No. 2004-145319 (Patent Document 3).

In the color imaging device with a microlens described in each of Patent Document 1 and Patent Document 2, the microlens is directly formed on the surface of the corresponding color filter. And in the color image pick-up element with a micro lens of patent document 3, the micro lens is formed on the planarization layer formed on the color filter.
JP 59-122193 A JP 2005-294467 A JP 2004-145319 A

  Conventional microlenses are usually formed by a thermal reflow method.

  Therefore, in the conventional example in which the micro lens is directly formed on the surface of the corresponding color filter, the unevenness of the color filter surface is reflected on the surface of the thin portion of the peripheral portion of the micro lens, and the periphery of the micro lens is The optical performance of the thin part of the part decreases, and as a result, light incident on the corresponding photoelectric conversion element through the color filter from the thin part of the peripheral part of the microlens is generated from the corresponding photoelectric conversion element There has been a problem that the generated electrical signal may generate noise or an electrical signal that does not accurately correspond to the color of the color filter.

  In the conventional example in which the microlens is formed on the flattening layer formed on the corresponding color filter, the unevenness of the color filter surface is not reflected on the surface of the microlens, and the optical as a microlens However, the process of forming the planarization layer increases the manufacturing cost of the color image sensor with microlenses. Furthermore, since the flattening layer increases the distance from the microlens to the photoelectric conversion element and reduces the condensing characteristic of the microlens with respect to the photoelectric conversion element, the photosensitivity of the color imaging element is reduced by the flattening layer.

  Also, in the conventional color image sensor, adjacent microlenses are formed so that their periphery is separated from each other in order to prevent adjacent microlenses from being fused to each other when the microlenses are formed by the thermal reflow method. Is done. Therefore, the planarization layer under the microlens is exposed between the adjacent microlenses. The light incident on the part between the adjacent microlenses is not guided to the corresponding photoelectric conversion element through the color filter by the microlens, and the photosensitivity of the imaging element can be further improved. There wasn't.

  The present invention has been made under the above circumstances, and the object of the present invention is to provide a microlens even if a microlens is directly formed on a color filter corresponding to a photoelectric conversion element in order to improve the photosensitivity of an image pickup element. Providing a microlens manufacturing method for a color image sensor that can further improve the photosensitivity and lower the manufacturing cost without degrading the optical performance, and providing a microlens adjacent to the color image sensor. The object is to provide a microlens array that can sufficiently function as a microlens even between lenses.

  In order to achieve the above-described object of the present invention, a method for manufacturing a microlens for a color image sensor according to the present invention includes: a planarization layer that forms a planarization layer on a plurality of photoelectric conversion elements on a semiconductor substrate of an image sensor. Forming step; forming a color filter layer of a desired color corresponding to each of the plurality of photoelectric conversion elements on the planarizing layer; and forming a layer of photosensitive lens material on the color filter layer A photosensitive lens material layer forming step for forming the photosensitive lens material; pattern exposure using a photomask having a controlled transmittance distribution so that a microlens is formed on the corresponding photoelectric conversion element after development. An exposure step; a development step of developing the pattern-exposed photosensitive lens material layer to form a microlens on a corresponding photoelectric conversion element; and a developed micro It is characterized by comprising; a curing step of curing the lens.

  In addition, the microlens array according to the present invention has the same curvature from its apex to its base end over the entire circumference by the microlens manufacturing method of the color image pickup device configured as described above. It is characterized in that a certain microlens is formed two-dimensionally.

  In the microlens manufacturing method for a color image pickup device according to the present invention, the flattening layer is formed on the plurality of photoelectric conversion elements on the semiconductor substrate of the image pickup device by the flattening layer forming step, and then on the flattening layer. Then, a color filter layer of a desired color is formed corresponding to each of the plurality of photoelectric conversion elements by the color filter layer forming step, and further, the photosensitive lens material layer is formed on the color filter layer by the photosensitive lens material layer forming step. A layer is formed.

  Since the planarizing layer for the photosensitive lens material layer is not formed between the color filter layer and the photosensitive lens material layer, the manufacturing cost can be reduced as compared with the conventional example described above. Furthermore, since there is no such flattening layer, the distance from the microlens to the photoelectric conversion element is reduced. Therefore, in the case of the above-described conventional example in which the amount of light incident on the corresponding photoelectric conversion element through the microlens and the color filter layer formed later from the photosensitive lens material layer has such a flattening layer, In comparison, the light sensitivity of the color image sensor increases.

  In the microlens manufacturing method for a color image pickup device according to the present invention, the photosensitive lens material layer further uses a photomask whose transmittance distribution is controlled from the exposure step, and the color on the photoelectric conversion device corresponding to the color after development. Pattern exposure is performed so that microlenses are formed on the filter layer, and then the pattern-exposed photosensitive lens material layer is developed by a development process to form microlenses on the color filter layer on the corresponding photoelectric conversion element. Finally, the developed microlens is cured by a curing process.

  In order to improve the photosensitivity of the image sensor, the color filter surface of the color filter layer is formed on the surface of the microlens formed directly on the color filter layer in correspondence with the photoelectric conversion element in this way without using the thermal reflow method. Are not reflected on the surface of the thin portion of the peripheral portion of the microlens. Accordingly, the optical performance of the thin portion of the peripheral portion of the microlens is not deteriorated, and the incident portion enters the corresponding photoelectric conversion element through the color filter from the thin portion of the peripheral portion of the microlens. Light does not cause noise in the electric signal generated from the corresponding photoelectric conversion element, and does not cause an electric signal that does not accurately correspond to the color of the color filter.

  Further, as described above, by forming the microlens without using the thermal reflow method, adjacent microlenses are not fused to each other. Therefore, each micro lens can be formed over the entire color filter of the corresponding pixel, and the color filter under the micro lens can be prevented from being exposed between adjacent micro lenses. And since the light which entered into the part between such adjacent microlenses is also guide | induced to a corresponding photoelectric conversion element through a color filter by a microlens, the photosensitivity of an image pick-up element can further be improved.

  The microlens array according to the present invention is formed by two-dimensionally arranging the microlenses formed by the microlens manufacturing method of the color imaging element, which is configured as described above. The microlens can have a curvature from its apex to its base end over its entire circumference.

  Therefore, the microlens array according to the present invention can sufficiently function as a microlens even between adjacent microlenses in a color imaging device.

  Hereinafter, a microlens manufacturing method of a color imaging device according to the present invention and a microlens array manufactured by the microlens manufacturing method will be described in detail with reference to the accompanying drawings.

  FIG. 1A shows a schematic longitudinal section of an image sensor 14 in which a plurality of CMOS photoelectric conversion elements 12 are provided on a semiconductor substrate 10. In this embodiment, the photoelectric conversion element is a CMOS photoelectric conversion element 12. However, according to the concept of the present invention, the photoelectric conversion element may be a CCD photoelectric conversion element. Such a configuration of the image sensor 14 is well known and will not be described in further detail here.

  In addition, the size of a rectangular pixel such as a rectangle or a square in plan view to which the present invention can be applied is in a range of approximately 10 μm to approximately 1 μm, and in this embodiment, in a range of approximately 2.7 μm to approximately 2.2 μm. is there.

  Next, as shown in FIG. 1B, the planarization layer 16 is formed on the surface of the image sensor 14 where the plurality of photoelectric conversion elements 12 are open. In this embodiment, the planarizing layer 16 is formed by applying a thermosetting acrylic resin by spin coating and then heat-curing it, and has a thickness of approximately 0.1 μm.

  Next, as shown in FIG. 1C, a color filter layer 18 of a desired color is formed on the planarizing layer 16 corresponding to each of the plurality of photoelectric conversion elements 12. In this embodiment, the color filter layer 18 is arranged in a desired arrangement corresponding to the plurality of photoelectric conversion elements 12 and has three colors of color filters 18g, 18b, red having a predetermined thickness. Each of the thicknesses including 18r is approximately 1 μm.

  In this embodiment, each of the three color filters 18g, 18b, and 18r is formed from a negative color resist layer of each color that is uniformly and sequentially formed on the entire planarizing layer 16, and the desired photoelectric conversion element 12 is obtained. It is formed by a photolithography method so that it remains only at a position corresponding to. However, instead of the negative color resist layer of each color, a positive color resist layer of each color is used, and only from the positive color resist layer of each color to a position corresponding to the desired photoelectric conversion element 12, respectively. The color filters 18g, 18b, and 18r of the colors may be formed by photolithography.

  The green color resist layer is, for example, an organic solvent such as cyclohexane or PGMEA, a polymer varnish, a monomer, a starting material and the like as a coloring material. I. Pigment yellow 139, C.I. I. Pigment green 36, and C.I. I. It can be prepared by adding Pigment Blue 15: 6.

  In addition, the blue color resist layer may be C.I. as a color material for organic solvents such as cyclohexane and PGMEA, polymer varnish, monomer, and starting material. I. Pigment blue 15: 6, and C.I. I. It can be prepared by adding Pigment Violet 23.

  Further, the red color resist layer 18 is formed of, for example, C.I. as a colorant on an organic solvent such as cyclohexane or PGMEA, a polymer varnish, a monomer, and a starting material. I. Pigment red 117, C.I. I. Pigment red 48: 1, and C.I. I. It can be prepared by adding Pigment Yellow 139.

  Each of the color filters 18g, 18b, and 18r can be formed by various known methods other than those described above as long as each of the color filters 18g, 18b, and 18r can be formed with desired optical characteristics at a position corresponding to the desired photoelectric conversion element 12. Can be formed.

  Next, as shown in FIG. 1D, a photosensitive lens material layer 20 is formed on the color filter layer 18.

  In this embodiment, the photosensitive lens material layer 20 is formed by spin-coating a positive photosensitive lens material on the color filter layer 18 and then pre-baking, and has a thickness of approximately 0.73 μm. ing. Such a positive photosensitive lens material can be mainly composed of an acrylic resin, a phenol resin, or a styrene resin.

  An example of such a photosensitive lens material is sold under the name of product number MFR401-M from JSR Corporation in Japan. At 90 ° C. after spin coating while the imaging device 14 in which the planarizing layer 16 and the color filter layer 18 are formed on the surface where the photoelectric conversion device 12 is opened as described above is rotated at 2000 rpm. Pre-baked for 90 seconds.

  Next, as shown in FIG. 2A, the photosensitive lens material layer 20 is formed on the color filters 18g, 18b, and 18r of the color filter layer 18 on the corresponding photoelectric conversion element 12 after development. 2B, exposure is performed using a photomask 24 composed of a halftone mask having a gradation of a pattern so that the microlenses 22g, 22b, and 22r shown in FIG. 2B are formed. 26.

  FIG. 3A shows a schematic plan view of such a photomask 24. Normally, a photomask has a size five times as large as a pattern to be actually formed, and pattern exposure is performed by reducing the pattern to 1/5 during pattern exposure. Further, the photomask 24 sequentially changes the gradation (gray scale) concentrically. The concentric gradation is formed by adjusting the number of fine black dots (or white dots) per unit area on the photomask 24, for example, when the size is reduced to 1/5, for example, a size smaller than the wavelength of the exposure light. . As a result, the photomask 24 can have concentric gradations having different light transmittances concentrically.

  In the photomask 24 used in this embodiment, the number of black dots is increased toward the center in a concentric shape centering on a line passing through the center of the photoelectric conversion element 12, and as a result, the number of black dots is increased toward the center. The light transmittance is reduced.

  The photomask 24 of this embodiment is a 5 × reticle, and has a pattern with a size that is 5 times larger than the size of the pattern exposed on the surface of the photosensitive lens material layer 20. Then, using a stepper exposure apparatus (not shown), the pattern of the photomask 24 is reduced to 1/5, and the surface of the photosensitive lens material layer 20 is exposed 26 around the line passing through the center of the corresponding photoelectric conversion element 12. ing.

In this embodiment, light having a wavelength of 365 nm in the ultraviolet region is used for the exposure 26, and the irradiation amount is 250 mj / cm ² .

  Next, the photosensitive lens material layer 20 subjected to pattern exposure as described above is developed, and the microlenses 22g and 22b on the corresponding color filters 18g and 18b of the color filter layer 18 on the corresponding photoelectric conversion element 12 and 18r. , And 22r are formed.

  In this embodiment, for example, an alkaline developer (TMAH (tetramethylammonium hydroxide) aqueous solution: 0.05% by weight) was used for the development, and paddle development was performed for 60 seconds.

  The microlenses 22g, 22b, and 22r formed by development as described above are finally cured.

In this embodiment, a combination of light irradiation treatment and subsequent heat treatment is adopted as the curing treatment. In the light irradiation treatment, the light having the same wavelength of 365 nm as the light in the ultraviolet region used for the exposure 26 described above was irradiated at an exposure amount of 200 mj / cm ² . Incidentally, the exposure amount is preferably 2,500 mJ / cm ² or less at 200 mj / cm ² or more. In the heat treatment, a hot plate was used to perform a heat treatment at 160 ° C. for 3 minutes, followed by a heat treatment at 200 ° C. for 6 minutes.

  It should be noted here that a combination of a light irradiation process and a subsequent heat treatment is employed as the curing process. In the curing process using only the heat treatment, heat dripping occurs in the resin forming the microlens by heating, and the microlenses 22g, 22b, formed by development as described above corresponding to the pixels having a square shape in plan view. And in each of 22r, the curvature of each outer surface when it goes to arbitrary surrounding directions (for example, the direction along a diagonal, or the direction along a side) over the perimeter from each vertex to each base end. May not be equal.

  However, by performing the light irradiation treatment before the heat treatment, the light is applied to the respective surfaces of the microlenses 22g, 22b, and 22r formed by the development as described above corresponding to the pixels in the plan view. By performing the irradiation treatment, the resin forming the microlens can be temporarily cured by heating in the heat treatment to such an extent that no thermal dripping occurs. As a result, each of the microlenses 22g, 22b, and 22r formed by development as described above corresponding to a pixel having a square shape in plan view has its apex even when the heat treatment is performed following the light irradiation treatment. The curvature of each outer surface can be kept equal when facing the arbitrary direction (for example, the direction along the diagonal line or the direction along the side) over the entire circumference from the base end to the base end.

Incidentally, in the above light irradiation process, be 2,500 mJ / cm ² or less in the range of the exposure amount of the same 365nm wavelengths of light and light in the ultraviolet range is used in 200 mj / cm ² or more for exposure 26 described above Although it is preferable, if the exposure amount is 200 mj / cm ² or less, there is a high possibility that the desired temporary curing effect cannot be obtained. On the other hand, if the exposure amount is 2500 mj / cm ² or more, the time spent for the temporary curing becomes too much, and the possibility of adversely affecting the productivity of the color image sensor increases.

  In this way, the color filter of the color filter layer 18 formed on the surface of the semiconductor substrate 10 of the imaging device 14 corresponding to the plurality of photoelectric conversion elements 12 via the planarization layer 16 on the surface where the plurality of photoelectric conversion elements 12 are opened. A plurality of microlenses 22g, 22b, and 22r further formed on 18g, 18b, and 18r are formed in this embodiment as shown in FIGS. 2B and 3B. The microlens array 28 is configured to be connected to each other with the thin film TF of the photosensitive lens material remaining between the adjacent microlenses 22g, 22b, and 22r.

  In this embodiment, the thin film TF has a thickness of 0.13 μm, but this thickness is preferably in the range of 0.05 μm to 0.2 μm.

  Thus, when the microlens array 28 leaves the thin film TF of the photosensitive lens material between the microlenses 22g, 22b, and 22r adjacent to each other, each planar view corresponds to a plurality of square pixels. The microlenses 22g, 22b, and 22r adjacent to each other are arranged in an arbitrary direction around the entire circumference including four corners in the diagonal direction of the corresponding pixels from the respective vertexes to the respective base ends. It is possible to maintain the same curvature as the lens of each outer surface when heading in a direction (for example, a direction along a diagonal line or a direction along a side). As a result, each of the microlenses 22g, 22b, and 22r adjacent to each other corresponding to a plurality of pixels each having a square shape in plan view has a diagonal line corresponding to each pixel from the respective vertexes to the respective base ends. Good condensing property can be exhibited with respect to the photoelectric conversion element 12 corresponding to the entire circumference including the four corners of the direction. Furthermore, since the vicinity of the part connected to the thin film TF from the respective base ends of the microlenses 22g, 22b, and 22r also contributes to the light condensing to the corresponding photoelectric conversion element 12, the light condensing property to the photoelectric conversion element 12 is further improved. . The effect of improving the light collecting property becomes remarkable in the diagonal direction of the corresponding pixels of the microlenses 22g, 22b, and 22r.

  If the thin film TF of the photosensitive lens material does not remain between the microlenses 22g, 22b, and 22r, and the microlenses 22g, 22b, and 22r are formed separately from each other, the microlens 22g, The light incident on the surface portions of the color filters 18g, 18b, or 18r exposed between 22b and 22r is affected by the unevenness of the surface of the color filters 18g, 18b, or 18r. The surface of the color filter 18g, 18b, or 18r is exposed between the microlenses 22g, 22b, and 22r in a plurality of pixels each having a square shape in plan view. It is a corner. As a result, light incident on the photoelectric conversion element 12 corresponding to each of the microlenses 22g, 22b, and 22r via the color filters 18g, 18b, or 18r is transmitted between the microlenses 22g, 22b, and 22r. Of the surface of the color filter 18g, 18b, or 18r exposed at (1), particularly the unevenness of the surface portion of the color filter 18g, 18b, or 18r corresponding to the four corners in the diagonal direction of each pixel The received light is included, and noise may be generated in the electric signal generated by the photoelectric conversion element 12, or an electric signal that does not accurately correspond to the color of the corresponding color filter 18g, 18b, or 18r may be generated. Further, since there are no portions connected to the thin film TF from the respective base ends of the microlenses 22g, 22b, and 22r, it is natural that the connected portions correspond to the microlenses 22g, 22b, and 22r, respectively. Therefore, the light condensing property with respect to the photoelectric conversion element 12 is reduced accordingly. Such a decrease in the light condensing property becomes remarkable in the diagonal direction of the corresponding pixels of the micro lenses 22g, 22b, and 22r.

  In this embodiment, the thickness of the thin film TF is preferably in the range of 0.05 μm to 0.2 μm. The first reason is that the photosensitive lens material layer 20 is currently described above. The minimum thickness of the thin film TF that can be reliably controlled even after pattern exposure using a photomask 24, development processing, and further curing processing is 0.05 μm. is there. The second reason is that in the above-described conventional example in which the thickness of the thin film TF is 0.2 μm or more, a microlens is formed on the planarizing layer after the planarizing layer is formed on the color filter layer 18. Functionally the same as the planarizing layer, the distance from each of the microlenses 22g, 22b, and 22r to the corresponding photoelectric conversion element 12 is increased, and the light collection characteristics of the microlens with respect to the photoelectric conversion element 12 are reduced, so that the color This is because the light sensitivity of the image sensor is lowered.

  If the thickness of the thin film TF is in the range of 0.05 μm to 0.2 μm, the microlens applied to a pixel having a square shape in plan view and a size in the range of about 10 μm to about 1 μm The best condensing characteristics can be exhibited with respect to the corresponding photoelectric conversion elements 12 in all the regions including the region in the direction along the diagonal line of the peripheral portion of the pixel.

  In addition, the height of each of the plurality of microlenses 22g, 22b, and 22r from the surface of the corresponding color filter 18g, 18b, and 18r of the color filter layer 18 is 0.60 μm.

  Further, a plurality of photoelectric conversions are performed on the semiconductor substrate 10 of the image sensor 14 from the respective surfaces of the color filters 18g, 18b, and 18r corresponding to the color filter layer 18 on which the plurality of microlenses 22g, 22b, and 22r are formed. The so-called under-lens distance to the surface where the element 12 is open was 1.25 μm.

  The plurality of color filters 22g, 22b corresponding to the plurality of photoelectric conversion elements 12 of the image sensor 14 and the plurality of mutually connected micro lenses 18g, 18b, and 18r are included on the thus formed color filters 22g, 22b and 22r. In a color imaging device with a microlens array 28, adjacent microlenses 22g, 22b, and 22r corresponding to a plurality of pixels each having a square shape in plan view are thin films of photosensitive lens material between them. Since each of the microlenses 22g, 22b, and 22r is connected to each other leaving the TF, the color filter is also provided at the base of each circumference including the four diagonal corners of the corresponding pixel. The unevenness of the surface of the layer 18 is not reflected, and each of the entire circumference including the four corners in the diagonal direction of the corresponding pixel is included. Curvature from the vertex to the proximal end of each of the people is the desired optical performance can be exhibited unchanged. Furthermore, since the vicinity of the part connected to the thin film TF from the respective base ends of the microlenses 22g, 22b, and 22r also contributes to the light condensing to the corresponding photoelectric conversion element 12, the light condensing property to the photoelectric conversion element 12 is further improved. . The effect of improving the light collecting property becomes remarkable in the diagonal direction of the corresponding pixels of the microlenses 22g, 22b, and 22r.

  That is, each of the microlenses 22g, 22b, and 22r adjacent to each other includes a curvature and a square of the surface of the diagonal cross section in the rectangular pixel shown in FIG. The curvature of the surface of the cross section along the line connecting the center of each of the two sides facing each other and the center of the microlens 22g, 22b, or 22r in the shape pixel is the same.

  This means that light incident on the micro lens 22g, 22b, or 22r corresponding to the pixel from any direction along the entire circumference including the four corners in the diagonal direction of the pixel is incident on the pixel. It is possible to reach the corresponding optical conversion element 12 through the color filter 18g, 18b, or 18r corresponding to the pixel and the flattening layer 16 with the same optical characteristics by the microlenses 22g, 22b, or 22r corresponding to. Means. As a result, in all the pixels, the light incident on the corresponding photoelectric conversion element 12 through the entire area including the four corners in the diagonal direction of the corresponding color filter 18g, 18b, or 18r corresponds to the corresponding photoelectric conversion element 12. No noise is generated in the electric signal generated from the image signal, and no electric signal that does not exactly correspond to the color of the corresponding color filter 18g, 18b, or 18r is generated.

  On the other hand, when a microlens is formed corresponding to the entire surface of a pixel having a square shape in plan view by the thermal reflow method, the distance from the apex is different in the peripheral portion of the microlens, for example, in the direction and the side along the diagonal line. The curvature of the surface of the cross section in the direction along the line (that is, the direction substantially orthogonal to each of the two sides facing each other in the rectangular pixel) is not the same. In this case, in the microlens formed by the thermal reflow method corresponding to the entire surface of the square-shaped pixel in plan view, the peripheral portion corresponding to the periphery of the corresponding pixel particularly corresponds to the circumferential position thereof. At the four corners in the diagonal direction of the pixel, the aberration is different, and the light condensing property cannot be efficiently exhibited with respect to the photoelectric conversion element 12 of the corresponding pixel. As a result, in all the pixels, light incident on the corresponding photoelectric conversion element 12 through the corresponding color filter 18g, 18b, or 18r causes noise in the electric signal generated from the corresponding photoelectric conversion element 12. In addition, an electrical signal that does not exactly correspond to the color of the corresponding color filter 18g, 18b, or 18r is generated.

(A) is an outline of a semiconductor substrate having a plurality of photoelectric conversion elements of an image sensor before a color filter or a micro lens is formed by the method for manufacturing a micro lens of a color image sensor according to an embodiment of the present invention. FIG. 2B is a plan view of the planarization layer forming step included in the method of manufacturing the microlens for the color image sensor according to the embodiment of the present invention. It is a longitudinal cross-sectional view which shows a mode that the planarization layer was formed on the several photoelectric conversion element of the semiconductor substrate of the image pick-up element currently used; (C) is according to one Embodiment of this invention. In the color filter layer forming step included in the microlens manufacturing method of the color image sensor, a plurality of layers are formed on the planarization layers on the plurality of photoelectric conversion elements of the semiconductor substrate of the image sensor shown in FIG. of It is sectional drawing which shows a mode that the color filter layer containing the some color filter corresponding to a photoelectric conversion element was formed; and (D) is a color image sensor according to one embodiment of this invention In the photosensitive lens material layer step included in the microlens manufacturing method, a plurality of layers formed on the planarizing layers on the plurality of photoelectric conversion elements of the semiconductor substrate of the imaging element shown in FIG. It is sectional drawing which shows schematically a mode that the photosensitive lens material layer was formed on the color filter layer containing this color filter. (A) shows a plurality of semiconductor substrates of the image sensor shown in FIG. 1D in the exposure step included in the microlens manufacturing method of the color image sensor according to the embodiment of the present invention. The photosensitive lens material layer further formed on the color filter layer including a plurality of color filters formed on the planarizing layer on the photoelectric conversion element is micro-patterned on the color filter layer on the corresponding photoelectric conversion element after development. It is sectional drawing which shows a mode that the pattern exposure by which a lens is formed is shown schematically; And (B) is the image development process included in the micro lens manufacturing method of the color image pick-up element according to one embodiment of this invention 2A, the photosensitive lens material layer subjected to pattern exposure in FIG. 2A is developed to form a microlens, and the microlens thus formed is After being cured in the curing step included in the method for manufacturing a microlens for a color image sensor according to an embodiment of the invention, a plurality of color filters corresponding to a plurality of photoelectric conversion elements of the image sensor are mutually connected. It is sectional drawing which shows schematically a mode that the color image pick-up element with the micro lens array containing the connected micro lens was formed. (A) is a top view which shows roughly the photomask used in the exposure process included in the micro lens manufacturing method of the color image pick-up element according to one embodiment of this invention; and (B) Using the photomask shown in FIG. 3A, the photosensitive lens material layer on the plurality of color filters included in the color filter layer is subjected to pattern exposure, and then the photosensitive lens material layer is developed. It is a longitudinal cross-sectional view which expands and roughly shows the several micro lens obtained after making it harden | cure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Semiconductor substrate, 12 ... Photoelectric conversion element, 14 ... Imaging device, 16 ... Planarization layer, 18 ... Color filter layer, 18g, 18b, 18r ... Color filter, 20 ... Photosensitive lens material layer, 22g, 22b, 22r ... micro lens, 24 ... photomask, 28 ... micro lens array.

Claims (5)

A planarization layer forming step of forming a planarization layer on the plurality of photoelectric conversion elements of the semiconductor substrate of the imaging element;
Forming a color filter layer of a desired color corresponding to each of the plurality of photoelectric conversion elements on the planarizing layer;
Forming a photosensitive lens material layer on the color filter layer;
An exposure process in which a photosensitive lens material layer is subjected to pattern exposure so that a microlens is formed on a color filter layer on a corresponding photoelectric conversion element after development using a photomask having a controlled transmittance distribution;
Developing a pattern-exposed photosensitive lens material layer to form a microlens on a color filter layer on a corresponding photoelectric conversion element; and
A curing step of curing the developed microlens;
A method for manufacturing a microlens for a color imaging device.   2. The color imaging according to claim 1, wherein the photosensitive lens material is a positive photosensitive lens material, and the curing step includes light irradiation to the developed microlens and a heat treatment after the light irradiation. A microlens manufacturing method for an element. Wavelength of light used in the light irradiation of the curing process is 365 nm, the micro-color imaging device according to claim 2, irradiation amount is in the range of 200 mj / cm ² to 2,500 mJ / cm ^2, characterized in that Lens manufacturing method.   4. The microlens manufacturing method for a color imaging device according to claim 1, wherein microlenses having the same curvature from the apex to the base end are arranged two-dimensionally over the entire circumference. A microlens array of color imaging elements formed in the above manner.   The photosensitive lens material layer leaves a thickness of 0.05 μm to 0.2 μm between diagonal directions of microlenses adjacent to each other after the formation of the microlenses. Micro lens array of color image sensor.

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