Image sensor and manufacturing method thereof

Abstract

Provided is a technique capable of improving the accuracy of infrared detection by an image sensor. An image sensor (1A) is provided with: a substrate (2) on which a plurality of photodiodes are provided; a color filter (4) including a plurality of colored layers and having a plurality of first through-holes; an infrared shielding layer (6) that is provided on the color filter and has a plurality of second through-holes that communicate with each of the plurality of first through-holes; a plurality of infrared-transmitting layers (41) that fill one of the plurality of first through-holes and the second through-holes that communicate with the first through-hole; and a plurality of microlenses 51. With respect to the image sensor 1A, the entirety of the side wall of each of the plurality of second through-holes is in contact with the side surface of any one of the plurality of infrared transmission layers 41, and the upper surface of the infrared shielding layer has a maximum height HCH at a position with respect to the boundary of the plurality of infrared transmission layers 41. The maximum height HPH of the upper surface of each of the plurality of infrared-transmitting layers 41 is greater than the minimum height HCL and greater than or equal to the maximum height HCH, and the minimum height HCL is greater than or equal to the maximum height HCH.

Description

Technical Field

[0001] The present invention relates to an image sensor and a method for manufacturing the same. Background Art

[0002] An image sensor (or solid-state imaging element) has a substrate on which a plurality of photodiodes are formed that convert light into electrical signals of a magnitude corresponding to the intensity thereof. An image sensor has a structure that includes: a color filter located on the photodiodes for each color; an infrared transmission layer located on the photodiode for infrared light; and an infrared shielding layer provided on the color filter (for example, see Patent Document 1).

[0003] The image sensor described in Patent Document 1 has a structure in which the upper surface of the infrared transmission layer is lower than the upper surface of the infrared shielding layer. In this document, a color filter is formed on each color photodiode on a substrate, and after an infrared shielding layer is formed as an upper layer thereof, an infrared transmission layer is formed in a manner that fills the concave portion at the position of the infrared photodiode on the substrate, thereby manufacturing an image sensor having the above structure.

[0004] Patent Document 1: Japanese Patent No. 6317695 Summary of the invention

[0005] An object of the present invention is to provide a technology capable of improving the detection accuracy of infrared rays by an image sensor.

[0006] According to one aspect of the present invention, an image sensor is provided, wherein:

[0007] The image sensor has:

[0008] a substrate provided with a plurality of photodiodes;

[0009] a color filter including a plurality of coloring layers respectively disposed on a portion of the plurality of photodiodes, and having a plurality of first through holes respectively disposed at positions of another portion of the plurality of photodiodes;

[0010] an infrared shielding layer, which is disposed on the color filter, shields infrared rays of a specific wavelength and allows visible light to pass therethrough, and has a plurality of second through holes respectively connected to the plurality of first through holes;

[0011] a plurality of infrared light transmitting layers which respectively fill one of the plurality of first through holes and the second through hole connected to the first through hole, shield visible light and transmit infrared light of the specific wavelength; and

[0012] a plurality of micro lenses sandwiching the color filter, the infrared shielding layer, and the plurality of infrared transmitting layers and facing the plurality of photodiodes respectively;

[0013] The entire side wall of each of the plurality of second through holes is in contact with a side surface of any one of the plurality of infrared transmitting layers.

[0014] The upper surface of the infrared shielding layer has a maximum height H at a position relative to the boundary of the plurality of infrared transmitting layers. CH , and has a minimum height H at a position far from the above boundary CL ,

[0015] The maximum height H of the upper surface of each of the plurality of infrared transmission layers is PH Greater than the above minimum height H CL , and greater than or equal to the above maximum height H CH .

[0016] According to another aspect of the present invention, there is provided the image sensor according to the above aspect, wherein the upper surface of each of the plurality of infrared-transmitting layers is convex.

[0017] According to another aspect of the present invention, there is provided an image sensor according to any of the above aspects, wherein, in the above-mentioned upper surface of the above-mentioned infrared shielding layer, the heights of the plurality of first regions respectively adjacent to the above-mentioned plurality of second through holes are greater than the heights of the second regions respectively adjacent to the above-mentioned plurality of second through holes which sandwich the above-mentioned plurality of first regions.

[0018] According to still another aspect of the present invention, there is provided an image sensor according to any one of the above aspects, wherein one or more of the plurality of colored layers in contact with the plurality of infrared-transmitting layers has an inverted tapered cross-sectional shape.

[0019] According to yet another aspect of the present invention, a method for manufacturing an image sensor is provided, wherein:

[0020] The manufacturing method of the image sensor comprises the following steps:

[0021] A color filter including a plurality of coloring layers and having a plurality of through holes is formed in the following manner: the plurality of coloring layers are respectively provided on a portion of a plurality of photodiodes provided on a substrate, and the plurality of through holes are provided at positions of another portion of the plurality of photodiodes;

[0022] A plurality of infrared light transmission layers that shield visible light and transmit infrared light of a specific wavelength are formed by filling the plurality of through holes and protruding from the plurality of through holes;

[0023] forming an infrared shielding layer on the color filter that shields the infrared rays of the specific wavelength and transmits visible light in such a manner that the upper surface of the infrared shielding layer has a smaller height than the plurality of infrared transmitting layers;

[0024] applying a heat flow to the infrared shielding layer; and

[0025] Then, a plurality of micro lenses are formed so as to face the plurality of photodiodes respectively by sandwiching the color filter, the infrared shielding layer, and the plurality of infrared transmitting layers.

[0026] According to the present invention, a technology capable of improving the detection accuracy of infrared rays by an image sensor is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a perspective view showing a part of an image sensor according to an embodiment of the present invention.

[0028] Figure 2 yes Figure 1 A cross-sectional view of the image sensor along line II-II is shown.

[0029] Figure 3 Yes means Figure 1 and Figure 2 A cross-sectional view showing one process step of an example of a method for manufacturing an image sensor shown.

[0030] Figure 4 Yes means Figure 1 and Figure 2 A cross-sectional view showing another step of an example of a method for manufacturing an image sensor shown.

[0031] Figure 5 Yes means Figure 1 and Figure 2 A cross-sectional view showing another step of an example of a method for manufacturing an image sensor shown.

[0032] Figure 6 Yes means Figure 1 and Figure 2 A cross-sectional view showing still another step of an example of a method for manufacturing an image sensor shown.

[0033] Figure 7 It is a cross-sectional view showing a part of an image sensor according to a modification example of one embodiment of the present invention.

[0034] Figure 8 is a cross-sectional view showing a portion of an image sensor according to a comparative example.

[0035] Fig. 9is a cross-sectional view showing a portion of an image sensor according to another comparative example.

[0036] Fig.10 is a cross-sectional view showing a portion of an image sensor according to another comparative example.

[0037] Fig.11 This is a microscope image of the infrared shielding layer in front of the heat flow of Example 1 taken from an oblique direction.

[0038] Fig.12 This is a microscope image of the infrared shielding layer of Example 1 after heat flow, taken from an oblique direction.

[0039] Fig.13 Yes Fig.12 This is a microscope image of a cross section of an infrared shielding layer.

[0040] Fig.14 This is a microscope image obtained by photographing the infrared shielding layer before the heat flow of Comparative Example 1 from an oblique direction.

[0041] Fig.15 This is a microscope image obtained by photographing the infrared shielding layer of Comparative Example 1 after heat flow from an oblique direction.

[0042] Fig.16 Yes Fig.15 This is a microscope image of a cross section of an infrared shielding layer. DETAILED DESCRIPTION

[0043] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below make any of the above aspects more specific. The matters described below may be incorporated into the above aspects individually or in combination of multiple items.

[0044] In addition, the embodiments shown below illustrate the structure for realizing the technical idea of ​​the present invention, and the technical idea of ​​the present invention is not limited by the material, shape and structure of the following structural parts. Various changes can be made to the technical idea of ​​the present invention within the technical scope specified by the technical solution recorded in the claims.

[0045] In addition, in the drawings referred to below, the same reference numerals are used for elements having the same or similar functions and repeated descriptions are omitted. In addition, the drawings are schematic, and the relationship between the size in a certain direction and the size in other directions and the relationship between the size of a certain component and the size of other components may be different from the actual situation.

[0046] Figure 1 It is a perspective view showing a part of an image sensor according to an embodiment of the present invention. Figure 2It is along Figure 1 A cross-sectional view of the image sensor taken along line II-II is shown.

[0047] Figure 1 and Figure 2 The image sensor 1A shown is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge-Coupled Device) image sensor. The image sensor 1A includes: a substrate 2; a color filter 4 including a first coloring layer 42, a second coloring layer 43, and a third coloring layer 44; a microlens array 5; an infrared shielding layer 6; and an infrared transmitting layer 41.

[0048] In addition, in each of the drawings, the X direction is a direction parallel to the principal surface opposite to the microlens array 5 of the substrate 2. The Y direction is a direction parallel to the principal surface and intersecting with the X direction. The Z direction is a direction perpendicular to the X direction and the Y direction, that is, the thickness direction of the substrate 2. Here, as an example, the X direction and the Y direction are set to be perpendicular to each other.

[0049] <Substrate>

[0050] The substrate 2 is a semiconductor substrate such as a silicon substrate. Figure 2 As shown, a plurality of photodiodes 21 as photoelectric conversion elements are provided on the surface area of ​​the substrate 2. The plurality of photodiodes 21 include: photodiodes for each color, which are respectively opposite to the first coloring layer 42, the second coloring layer 43 and the third coloring layer 44; and photodiodes for infrared rays, which are opposite to the infrared transmission layer 41. The photodiodes for each color measure the intensity of visible light having a specific wavelength. The photodiodes for infrared rays measure the intensity of infrared rays. The photodiodes 21 are arranged in the X direction and the Y direction.

[0051] The image sensor 1A may further include a planarization layer on the main surface of the substrate 2 on the photodiode 21 side to improve adhesion.

[0052] <Color filter>

[0053] The color filter 4 includes a plurality of color layers having different transmission spectra. Here, the color filter 4 includes a first color layer 42, a second color layer 43, and a third color layer 44. The color filter 4 may include two or more color layers, and may not include three.

[0054] The first coloring layer 42, the second coloring layer 43, and the third coloring layer 44 have different transmission spectra. The first coloring layer 42, the second coloring layer 43, and the third coloring layer 44 are, for example, a red layer, a blue layer, a green layer, a yellow layer, a magenta layer, or a cyan layer, respectively. According to one example, the first coloring layer 42, the second coloring layer 43, and the third coloring layer 44 are a red layer, a blue layer, and a green layer. According to another example, the first coloring layer 42, the second coloring layer 43, and the third coloring layer 44 are a yellow layer, a magenta layer, and a cyan layer.

[0055] The color filter 4 has a plurality of first through holes. Figure 2 As shown, the first through hole is filled with the infrared transmitting layer 41 .

[0056] Regarding the color filter 4, the first through holes and the first colored layers 42 form a plurality of first columns extending in the X direction and arranged in the Y direction. Regarding each first column, the first through holes and the first colored layers 42 are alternately arranged in the X direction. The second colored layers 43 and the third colored layers 44 form a plurality of second columns extending in the X direction and arranged in the Y direction. Regarding each second column, the second colored layers 43 and the third colored layers 44 are alternately arranged in the X direction. Moreover, the first column and the second column are alternately arranged in the Y direction.

[0057] As described above, the first colored layer 42 , the second colored layer 43 , and the third colored layer 44 are respectively provided to face the photodiodes for the respective colors among the plurality of photodiodes 21 , and the plurality of first through holes are provided to face the photodiodes for infrared rays among the plurality of photodiodes 21 .

[0058] The color filter 4 is patterned by, for example, photolithography using a photosensitive material containing a colorant.

[0059] The film thicknesses of the colored layers included in the color filter 4 may be different from each other or the same. The film thickness of each colored layer may be, for example, in the range of 0.3 μm to 1.0 μm, or in the range of 0.4 to 0.7 μm.

[0060] <Infrared shielding layer>

[0061] The infrared shielding layer 6 is a layer provided on the color filter 4, shielding infrared rays of a specific wavelength and transmitting visible light. The infrared shielding layer 6 shields infrared rays of a wavelength band that can be detected as noise by each photodiode 21 facing the color filter 4. Thus, the detection accuracy of the photodiode 21 can be improved.

[0062] The infrared shielding layer 6 is disposed on the color filter 4 and has a plurality of second through holes respectively connected to the plurality of first through holes included in the color filter 4. Figure 2As shown, the second through hole is filled with the infrared transmitting layer 41 .

[0063] The infrared shielding layer 6 contains, for example, an infrared absorbing colorant and a transparent resin. The infrared absorbing colorant is, for example, a dye such as squarylium dye, chloronium dye, diammonium dye, anthraquinone dye, cyanine dye, phthalocyanine dye, dithiol dye, etc. The transparent resin is, for example, an acrylic resin, a polyamide resin, a polyimide resin, a polyurethane resin, a polyester resin, a polyether resin, a polyolefin resin, a polycarbonate resin, a polystyrene resin, a norbornene resin, etc.

[0064] The infrared shielding layer 6 can be formed by photolithography using a photosensitive material containing an infrared absorbing colorant, a polymerizable compound, a binder resin, a photopolymerization initiator, etc. The photosensitive material can contain additives such as a light stabilizer, an antioxidant, a heat stabilizer, and an antistatic agent for other functions.

[0065] The film thickness of the infrared shielding layer 6 may be, for example, in the range of 0.5 μm to 1.2 μm, or in the range of 0.7 to 1.0 μm.

[0066] <Infrared Transmitting Layer>

[0067] The infrared transmission layer 41 is an optical filter that blocks visible light and transmits infrared light of a specific wavelength. That is, the infrared transmission layer 41 transmits infrared light that can be detected by the photodiode 21 (the infrared photodiode described above) and blocks visible light that can be detected by the photodiode 21. The infrared transmission layer 41 can improve the detection accuracy of infrared light by the photodiode 21. The infrared light of the specific wavelength that can be detected by the photodiode 21 is, for example, near infrared light having a wavelength in the range of greater than or equal to 900 nm and less than or equal to 1100 nm.

[0068] The infrared ray transmission layer 41 is provided on the substrate 2 in such a manner that one of the plurality of first through holes of the color filter 4 and the second through hole of the infrared shielding layer 6 connected to the first through hole are respectively filled. Here, the infrared ray transmission layer 41 is arranged in the X direction and the Y direction. The infrared ray transmission layer 41 respectively fills the first through hole and the second through hole connected to the first through hole, and protrudes upward from the upper surface of the color filter 4.

[0069] The infrared transmission layer 41 contains, for example, an infrared transmission colorant. The infrared transmission colorant is preferably a material that transmits at least a portion of light in the near-infrared region and shields light in the visible region. The infrared transmission layer 41 may contain two or more color colorants as infrared transmission colorants, and may present black color by a combination of two or more color colorants. Alternatively, the infrared transmission layer 41 may contain an organic black colorant as an infrared transmission colorant.

[0070] The coloring agent may be a pigment or a dye, preferably a pigment, and more preferably an organic pigment. The infrared transmission layer 41 contains two or more coloring materials selected from red, green, blue, yellow, purple, and orange coloring agents, for example.

[0071] The infrared transmission layer 41 may contain inorganic oxide particles for adjusting the refractive index. Examples of the inorganic oxides are aluminum oxide, silicon oxide, zirconium oxide, titanium oxide, etc. In addition, the infrared transmission layer 41 may contain additives for having other functions, such as light stabilizers, antioxidants, heat stabilizers, and antistatic agents.

[0072] The infrared transmitting layer 41 can be formed by photolithography using a photosensitive material including an infrared transmitting colorant, a polymerizable compound, a binder resin, a photopolymerization initiator, and the like, for example.

[0073] The film thickness of the infrared ray transmitting layer 41 may be, for example, in the range of 0.9 μm to 2.3 μm, or in the range of 1.2 to 1.8 μm.

[0074] <Microlens Array>

[0075] The microlens array 5 is provided so as to face the substrate 2 with the color filter 4, the infrared shielding layer 6, and the infrared transmitting layer 41 interposed therebetween. The microlens array 5 is made of a colorless and transparent organic substance, for example, a polymer.

[0076] The microlens array 5 includes a plurality of microlenses 51. The microlenses 51 face the photodiodes 21 respectively, sandwiching the color filter 4, the infrared shielding layer 6, and the infrared transmitting layer 41 therebetween.

[0077] Each microlens 51 is a convex lens with a convex upper surface. Here, the orthographic projection of each microlens 51 to a plane perpendicular to the Z direction is circular. The orthographic projection may also have other shapes such as a chamfered quadrilateral. Each microlens 51 may be approximately hemispherical at the top and approximately quadrangular prism at the bottom.

[0078] The image sensor 1A includes a plurality of pixels arranged in the X direction and the Y direction. Here, each pixel includes the first to fourth sub-pixels. The first sub-pixel includes an infrared transmission layer 41, and a photodiode 21 and a microlens 51 opposite to the infrared transmission layer 41. The second sub-pixel includes a first coloring layer 42, and a photodiode 21 and a microlens 51 opposite to the first coloring layer 42. The third sub-pixel includes a second coloring layer 43, and a photodiode 21 and a microlens 51 opposite to the second coloring layer 43. The fourth sub-pixel includes a third coloring layer 44, and a photodiode 21 and a microlens 51 opposite to the third coloring layer 44.

[0079] Regarding the image sensor 1A, the upper surface of the infrared transmission layer 41 is located at a higher position than the upper surface of the infrared shielding layer 6. Here, "the upper surface of the infrared transmission layer 41 is located at a higher position than the upper surface of the infrared shielding layer 6" has the following meaning. That is, the upper surface of the infrared shielding layer 6 has a maximum height H at a position relative to the boundary of the plurality of infrared transmission layers 41. CH , and has a minimum height H at a position far from the above boundary CL Furthermore, the maximum height H of the upper surface of each of the plurality of infrared transmission layers 41 is shown. PH Greater than the minimum height H of the upper surface of the infrared shielding layer 6 CL (H CL <H PH ), and is greater than or equal to the maximum height H of the upper surface of the infrared shielding layer 6. CH (H CH ≤H PH Here, as long as the maximum height H of the upper surface of the infrared shielding layer 6 is satisfied CH and minimum height H CL Satisfy H CL ≤H CH The relationship is enough.

[0080] Figure 2 The image sensor 1A shown in the figure has a maximum height H of the upper surface of the infrared transmission layer 41. PH Greater than the maximum height H of the upper surface of the infrared shielding layer 6 CH The way to form H PH >H CH When the minimum height of the upper surface of the infrared ray transmission layer 41 is set to H PL When H PH >H CH The relationship between the image sensor 1A, such as Figure 2 As shown, the minimum height H of the upper surface of the infrared transmission layer 41 is formed PL Less than the maximum height H PH (HPL <H PH ), and the maximum height H of the upper surface of the infrared shielding layer 6 CH Equal relationship (H PL =H CH In this case, the upper surface of the infrared ray transmission layer 41 is composed of a plurality of layers having a maximum height H PH The area adjacent to the area and the height from the maximum height H PH To minimum height HPL In addition, the above H PH >H CL relationship.

[0081] about Figure 2 In the image sensor 1A shown in FIG. 1 , the upper surface of the infrared shielding layer 6 has a structure in which a portion (a first region D1 described later) in contact with the side surface of the infrared transmitting layer 41 is raised toward the infrared transmitting layer 41 (H CL <H CH ). However, regarding the image sensor 1A, the upper surface of the infrared ray transmission layer 41 is as shown in FIG. Figure 2 As shown in FIG. 1 , the upper surface of the infrared shielding layer 41 is formed to be H PH >H CH When the infrared shielding layer 6 is convex, the upper surface of the infrared shielding layer 6 is not limited to Figure 2 That is, the upper surface of the infrared ray transmitting layer 41 satisfies H PH >H CH When the infrared shielding layer 6 is convex, the maximum height H of the upper surface of the infrared shielding layer 6 CH and minimum height H CL Can be formed into Figure 2 H CL <H CH The relationship can also be expressed as H CL = CH In the latter H CL = CH Although not shown in the figure, the upper surface of the infrared shielding layer 6 is flat.

[0082] Although not shown in the figure, the image sensor 1A may be formed so that the maximum height H of the upper surface of the infrared ray transmission layer 41 is PH and the maximum height H of the upper surface of the infrared shielding layer 6 CH Equal relationship (H PH =H CH ). However, if the above H PH >H CL The relationship between is a condition, so the maximum height H of the upper surface of the infrared shielding layer 6 is required. CHand minimum height H CL Formed as H CL <H CH That is, with respect to the formation of H PH =H CH The relationship between the image sensor 1A and Figure 2 Similarly, the upper surface of the infrared shielding layer 6 has a structure in which the portion (first region D1) in contact with the side surface of the infrared transmitting layer 41 is raised toward the infrared transmitting layer 41. In this case, the upper surface of the infrared transmitting layer 41 has a maximum height H PH The area is flat (H PH =H PL ).

[0083] In the image sensor 1A, the entire side wall of each of the plurality of second through holes of the infrared shielding layer 6 is in contact with the side surface of any one of the plurality of infrared transmitting layers 41. That is, in the image sensor 1A, the entire side wall of the infrared shielding layer 6 is in contact with the infrared transmitting layer 41, and there is no gap between the infrared transmitting layer 41 and the infrared shielding layer 6.

[0084] As described later, the method for manufacturing the image sensor 1A forms the infrared shielding layer 6 after forming the color filter 4 and the infrared transmission layer 41. The infrared shielding layer 6 is formed by applying a heat flow after forming a pattern on the color filter 4 in such a manner that the upper surface thereof is lower in height than the upper surface of the infrared transmission layer 41. In this case, the upper surface of the infrared transmission layer 41 is located at a higher position than the upper surface of the infrared shielding layer 6, so that the color mixing of the infrared shielding layer 6 and the infrared transmission layer 41 caused by the application of a heat flow to the infrared shielding layer 6 can be suppressed. In addition, the generation of color mixing in the case where the upper surface of the infrared transmission layer 41 is located at a lower position than the upper surface of the infrared shielding layer 6 will be described later using a comparative example.

[0085] In the image sensor 1A, the difference H between the height of the upper surface of the infrared ray transmission layer 41 and the height of the upper surface of the infrared ray shielding layer 6 is D is 0 <H D , preferably 0.05μm≤H D , more preferably 0.1 μm ≤ H D Here, the height difference of the upper surface H D The maximum height H of the upper surface of the infrared transmission layer 41 is represented by PH Minimum height H of infrared shielding layer 6 CL The difference (H D =H PH -H CL ). On the other hand, if the height difference H of the upper surface DIf the thickness of the infrared ray transmitting layer 41 increases, coating spots tend to be easily generated when forming the infrared ray shielding layer 6. In addition, if the film thickness of the infrared ray transmitting layer 41 increases, it tends to be difficult to form the infrared ray transmitting layer 41. D Preferably H D ≤1.0μm, more preferably H D ≤0.8μm, more preferably H D ≤0.3μm.

[0086] By applying a heat flow to the infrared shielding layer 6, as described above, the entire surface of the side wall of the infrared shielding layer 6 can be brought into contact with the side surface of the infrared transmission layer 41, and a gap can be prevented from being generated between the infrared transmission layer 41 and the infrared shielding layer 6. Thus, the generation of stray light can be suppressed and noise can be reduced. The above-mentioned effect obtained by applying a heat flow to such an infrared shielding layer 6 can also be easily obtained when the infrared shielding layer 6 contains a dye as an infrared absorbing colorant rather than a pigment.

[0087] about Figure 2 In the image sensor 1A shown, the upper surface of each of the plurality of infrared ray transmitting layers 41 is convex. In this case, a lens effect is produced for focusing light of the microlenses 51 facing the infrared ray transmitting layers 41, and the detection accuracy of infrared rays is improved.

[0088] about Figure 2 In the image sensor 1A shown, in the upper surface of the infrared shielding layer 6, the plurality of first regions D1 adjacent to the plurality of second through holes are higher than the second regions D2 sandwiching the plurality of first regions and adjacent to the plurality of second through holes. Here, in the upper surface of the infrared shielding layer 6, the portion in contact with the side surface of the infrared transmission layer 41 is raised toward the infrared transmission layer 41. In the case where a valley is formed between the side surface of the infrared shielding layer 6 and the side surface of the infrared transmission layer 41, it is easy to generate defects such as pores (voids) when forming the microlens array 5. Regarding the image sensor 1A, as described above, the first region D1 on the upper surface of the infrared shielding layer 6 is higher than the second region D2, thereby suppressing the generation of defects such as pores (voids).

[0089] Regarding the infrared shielding layer 6, if a dye is used as the infrared absorbing colorant instead of a pigment, the portion of the upper surface of the infrared shielding layer 6 that contacts the side surface of the infrared transmitting layer 41 is likely to have a structure that bulges toward the infrared transmitting layer 41. Therefore, the effect of suppressing voids obtained by applying a heat flow to the infrared shielding layer 6 is improved when the infrared shielding layer 6 contains a dye instead of a pigment as the infrared absorbing colorant.

[0090] The image sensor 1A can be manufactured, for example, by the following method. Figures 3 to 6 Respectively represent Figure 1 and Figure 2 1A is a cross-sectional view showing steps included in an example of a method for manufacturing the image sensor 1A.

[0091] In this method, first, the color filter 4 is formed on the substrate 2 .

[0092] As described above, the color filter 4 includes the first coloring layer 42, the second coloring layer 43, and the third coloring layer 44, and has a plurality of first through holes. Figure 3 As shown in FIG. 1 , the first through holes T are located between the first colored layers 42 adjacent to each other in the X direction. In addition, the first through holes T are located between the second colored layers 43 adjacent to each other in the Y direction.

[0093] The first coloring layer 42 is formed by forming a coating film composed of a photosensitive material containing a colorant on the substrate 2, and patterning the coating film by a photographic method including exposure, development, and sintering. The second coloring layer 43 and the third coloring layer 44 are also formed by the same method as the first coloring layer 42. The order of forming the first coloring layer 42, the second coloring layer 43, and the third coloring layer 44 is arbitrary.

[0094] The patterning of the first coloring layer 42, the second coloring layer 43, and the third coloring layer 44 is performed in such a manner that a plurality of first columns formed by the first through holes T and the first coloring layer 42 being alternately arranged in the X direction and a plurality of second columns formed by the second coloring layer 43 and the third coloring layer 44 being alternately arranged in the X direction are alternately arranged in the Y direction.

[0095] As the coloring material contained in the first coloring layer 42, the second coloring layer 43, and the third coloring layer 44, organic or inorganic pigments can be used alone or in combination of two or more. The pigment is preferably a pigment with high color development and high heat resistance, especially a pigment with high resistance to thermal decomposition, and an organic pigment is usually used. Examples of the pigment that can be used include organic pigments such as phthalocyanines, azos, anthraquinones, quinacridones, dioxazines, anthrone, indanones, perenes, thioindigos, isoindolines, quinophthalones, and diketopyrroles.

[0096] Next, if Figure 4 As shown, an infrared ray transmitting layer 41 is formed on the substrate 2 .

[0097] exist Figure 4 in Figure 3 The infrared ray transmitting layer 41 is formed at the position of the first through hole T shown, and the infrared ray transmitting layer 41 and the first colored layer 42 are arranged alternately.

[0098] The infrared transmitting layer 41 is patterned by photolithography including exposure, development, and sintering using a photosensitive material containing an infrared transmitting colorant so as to fill each of the plurality of first through holes T and protrude from the plurality of first through holes T.

[0099] Next, the infrared shielding layer 6 is formed on the color filter 4 and a heat flux is applied thereto. Figure 5 and Figure 6 2 is a cross-sectional view showing a step of forming the infrared shielding layer 6 on the first colored layer 42 included in the color filter 4 . Figure 5 This is a cross-sectional view of the process before applying heat flow to the infrared shielding layer 6. Figure 6 This is a cross-sectional view of a process after heat flow is applied to the infrared shielding layer 6 .

[0100] like Figure 5 As shown, first, the infrared shielding layer 6 is formed on the color filter 4 using a photosensitive material containing an infrared absorbing colorant so that its upper surface has a lower height than the upper surface of the infrared transmitting layer 41. The infrared shielding layer 6 is formed by a photolithography method including exposure and development.

[0101] At a point in time before heat flow is applied to the infrared shielding layer 6 by sintering, as Figure 5 As shown in FIG. 1 , at least a portion of the side surface of the infrared shielding layer 6 (the side wall of the second through hole) is not in contact with the side surface of the infrared transmission layer 41, and a groove-shaped gap is formed between the infrared transmission layer 41. By applying a heat flow to the infrared shielding layer 6, as shown in FIG. Figure 6 As shown, the entire side surface of the infrared shielding layer 6 is in contact with the side surface of the infrared transmission layer 41, so that the groove-shaped gap formed between the infrared shielding layer 6 and the infrared transmission layer 41 disappears. In addition, according to one example, the portion of the upper surface of the infrared shielding layer 6 that is in contact with the side surface of the infrared transmission layer 41 is raised toward the infrared transmission layer 41 by the heat flow.

[0102] Next, a microlens array 5 including a plurality of microlenses 51 is formed to obtain Figure 1 and Figure 2 Image sensor 1A is shown.

[0103] The microlenses 51 are formed in such a manner that the color filter 4, the infrared shielding layer 6, and the infrared transmission layer 6 are sandwiched in between and are respectively opposite to the plurality of photodiodes 21. For example, each microlens 51 is formed by an etch-back method. Regarding the etch-back method, first, a transparent resin layer for forming each microlens 51 is formed in such a manner that the color filter 4, the infrared shielding layer 6, and the infrared transmission layer 6 are sandwiched in between and are opposite to the substrate 2. Next, a resist pattern having a shape (lens shape) of a plurality of hemispherical arrangements is formed on the transparent resin layer. Moreover, the shape (lens shape) of the resist pattern is transferred to the transparent resin layer by dry etching of the transparent resin layer having the resist pattern, thereby forming a plurality of microlenses 51.

[0104] Transparent resins used for forming microlenses 51 include, for example, acrylic resins, polyamide resins, polyimide resins, polyurethane resins, polyester resins, polyether resins, polyolefin resins, polycarbonate resins, polystyrene resins, and norbornene resins.

[0105] The microlenses 51 can also be formed without an etching mask. That is, first, a coating film made of a photosensitive material is formed in such a manner that the color filter 4, the infrared shielding layer 6, and the infrared transmitting layer 6 are sandwiched therebetween and face the substrate 2. Next, the coating film is patterned by a photolithography method including exposure and development, and a plurality of microlenses 51 made of a cured product of a photosensitive material are formed in such a manner that the color separation filter 4 is sandwiched therebetween and face the photodiodes 21, respectively. In addition, it is preferred that the patterning further includes a heat flow based on heating after development.

[0106] As mentioned above, obtain Figure 1 and Figure 2 Image sensor 1A is shown.

[0107] The image sensor 1A obtained by this method has excellent detection accuracy for infrared rays. This will be described below with reference to a comparative example.

[0108] About reference Figures 3 to 6 In the manufacturing method of the image sensor 1A described above, after forming the infrared transmission layer 41, the infrared shielding layer 6 is formed so that the upper surface thereof has a lower height than the infrared transmission layer 41, and a heat flow is applied thereto. Since the upper surface of the infrared transmission layer 41 is located at a higher position than the upper surface of the infrared shielding layer 6, the upper surface of the infrared transmission layer 41 is not partially covered by the infrared shielding layer 6 due to the application of the heat flow to the infrared shielding layer 6, and thus the occurrence of color mixing due to this can be suppressed.

[0109] Furthermore, after forming the infrared transmission layer 6, the infrared shielding layer 6 is formed in a manner that fills the recessed portion and a heat flow is applied thereto, so that the entire side surface of the infrared shielding layer 6 can be brought into contact with the side surface of the infrared transmission layer 41 as described above, and the generation of a groove-shaped gap can be suppressed. Since there is no groove-shaped gap, the generation of stray light due to the small thickness of the infrared shielding layer 6 at this position can be suppressed, and noise can be reduced.

[0110] In addition, by applying a heat flow to the infrared shielding layer 6, not only can a gap not be generated between the infrared transmission layer 41 and the infrared shielding layer 6, but as described above, a structure can be formed in which a portion of the upper surface of the infrared shielding layer 6 that contacts the side surface of the infrared transmission layer 41 is raised toward the infrared transmission layer 41. In this case, the generation of pores (voids) can be suppressed.

[0111] Figure 8 1 is a cross-sectional view showing a portion of an image sensor according to a comparative example. Figure 8 In the image sensor 100A shown, the upper surface of the infrared ray transmitting layer 41 is located lower than the upper surface of the infrared ray shielding layer 6 and has a concave shape.

[0112] The image sensor 100A is manufactured by a method including the following steps in order: a step of forming a color filter 4 including a second coloring layer 42 on a substrate 2; a step of forming an infrared shielding layer 6 on the color filter 4; and a step of forming an infrared transmission layer 41. In this step order, the infrared transmission layer 41 is formed by spin coating on the substrate 2 by photolithography in a manner that fills the first through hole and the second through hole respectively provided in the color filter 4 and the infrared shielding layer 6, and in a manner that makes the height of the upper surface smaller than that of the upper surface of the infrared shielding layer 6. In this case, the upper surface of the infrared transmission layer 41 is as shown in FIG. Figure 8 It is easy to change into a concave shape as shown.

[0113] When the upper surface of the infrared ray transmitting layer 41 has a concave shape as in the image sensor 100A, the light focusing effect obtained by the microlens 51 facing thereto is weakened, and the infrared ray detection accuracy is reduced.

[0114] Fig. 9 and Fig.10 Each of them is a cross-sectional view showing a part of an image sensor according to another comparative example. Fig. 9 The image sensor 100B shown and Fig.10 In the image sensors 100C shown, the upper surface of the infrared ray transmitting layer 41 is located lower than the upper surface of the infrared ray shielding layer 6 , and the side surfaces of the infrared ray shielding layer 6 are formed in a tapered shape.

[0115] The image sensors 100B and 100C are manufactured by changing the order of the process of forming the infrared ray shielding layer 6 and the process of forming the infrared ray transmitting layer 41 with respect to the above-mentioned manufacturing method of the image sensor 100A. That is, the image sensors 100B and 100C are manufactured by a method including the process of forming the color filter 4 including the first colored layer 42, the process of forming the infrared ray transmitting layer 41, and the process of forming the infrared ray shielding layer 6 in this order.

[0116] In this process sequence, for the infrared shielding layer 6, a photosensitive material containing an infrared absorbing colorant is applied to the upper surface of the infrared transmitting layer 41 and the upper surface of the color filter 4, and a pattern is formed on the color filter 4 by a photolithography method including exposure, development, and sintering. The above-mentioned dye pigment is mostly used as the infrared absorbing colorant for the infrared shielding layer 6. Compared with the photosensitive material containing a pigment, the photosensitive material containing a dye pigment is more likely to have its side surface tapered by heat flow during sintering.

[0117] about Fig. 9 In the image sensor 100B shown, the side surface of the infrared shielding layer 6 is formed into a tapered shape, covering a portion of the upper surface adjacent to the side surface of the infrared transmitting layer 41, so that color mixing is likely to occur. Fig.10 In the image sensor 100C shown, the tapered side surface of the infrared shielding layer 6 exists in the pixel including the first colored layer 42 , so stray light is likely to be generated.

[0118] <Modification>

[0119] Figure 7 FIG. 1 is a cross-sectional view showing a portion of an image sensor according to a modification of the image sensor 1A. In addition to the first colored layer 42 having an inverted tapered cross-sectional shape, Figure 7 The image sensor 1B shown is Figure 1 and Figure 2 The first coloring layer 42 has an inverted cone-shaped cross-section, and the infrared light transmitting layer 41 is difficult to fall off due to the anchoring effect. The coloring layer having an inverted cone-shaped cross-section can be obtained by, for example, appropriately combining and adding an appropriate amount of an additive such as an ultraviolet absorber to a photosensitive material forming the coloring layer, and other known techniques.

[0120] Example

[0121] Next, test examples conducted in connection with the present invention are described.

[0122] (Example 1)

[0123] In the method shown below, a Figure 6The image sensor 1A shown includes a portion of the structure (hereinafter referred to as a “partial structure” or a “partial structure of the image sensor”).

[0124] ·1st process

[0125] First, three photosensitive materials containing different pigments are prepared. Using these materials, a first coloring layer 42, a second coloring layer 43, and a third coloring layer 44 are patterned on a substrate 2 by a photolithography method including exposure, development, and sintering to form a color filter 4 (see Figure 3 Here, the first coloring layer 42, the second coloring layer 43, and the third coloring layer 44 are respectively a red layer, a green layer, and a blue layer. The film thickness of each of these coloring layers is 0.5 μm.

[0126] · Second process

[0127] Next, a photosensitive material containing an infrared-transmitting colorant, a polymerizable compound, a binder resin, and a photopolymerization initiator is applied to form a coating film on the color filter 4 and on the portion of the upper surface of the substrate 2 not covered by the color filter 4. Here, a mixed colorant of red organic pigment, green organic pigment, and blue organic pigment is used as the infrared-transmitting colorant.

[0128] Next, the coating film is patterned by a photolithography method including exposure, development, and sintering, thereby forming an infrared transmission layer 41 that fills the first through hole T and protrudes from the first through hole T (see Figure 4 The film thickness of the infrared ray transmission layer 41 obtained was 1.5 μm. Here, the film thickness of the infrared ray transmission layer 41 is represented by Figure 2 The maximum height H shown PH .

[0129] ·3rd process

[0130] Next, a photosensitive material containing an infrared absorbing colorant, a polymerizable compound, an acrylic resin, and a photopolymerization initiator is applied to the color filter 4 so that its upper surface has a lower height than the infrared transmitting layer 41 to form a coating film. Here, an aromatic acid dye is used as the infrared absorbing colorant. Next, the coating film is patterned by a photolithography method including exposure and development, thereby forming an infrared shielding layer 6 (see Figure 5 ).

[0131] Fig.11 This is an electron microscope photograph taken from an oblique direction of the partial structure of the infrared shielding layer 6 after exposure and development obtained in the third step and before heat flow.

[0132] ·Step 4

[0133] Next, the infrared shielding layer 6 obtained in the third step is sintered to apply heat flow. Thus, a partial structure of the image sensor 1A is manufactured in which the microlens array 5 is omitted compared to the image sensor 1A. The film thickness of the infrared shielding layer 6 is 0.7 μm, and the difference H between the height of the upper surface of the infrared transmission layer 41 and the height of the upper surface of the infrared shielding layer 6 is 0.7 μm. D (H D =H PH -H CL ) is 0.3 μm. Here, the film thickness of the infrared shielding layer 6 is expressed from Figure 2 Minimum height H shown CL The film thickness is obtained by subtracting the film thickness of the color filter 4.

[0134] Fig.12 This is an electron microscope photograph taken from an oblique direction of the partial structure of the infrared shielding layer 6 after the heat flow obtained in the fourth step. Fig.13 This is an electron microscope photograph of the cross section of the local structure. Fig.11 By comparing the infrared ray shielding layer 6, it can be confirmed that the gap between the infrared ray shielding layer 6 and the infrared ray transmission layer 41 disappears due to the heat flow of the infrared ray shielding layer 6. On the other hand, the upper surface of the infrared ray transmission layer 41 is higher than the upper surface of the infrared ray shielding layer 6, so it can be confirmed that the upper surface of the infrared ray shielding layer 6 is not covered by the infrared ray shielding layer 6 to which the heat flow is applied. Therefore, it can be seen that the image sensor 1A obtained by the manufacturing method of Example 1 suppresses the generation of color mixing and stray light.

[0135] (Comparative Example 1)

[0136] ·1st process

[0137] The color filter 4 is formed on the substrate 2 by the same method as the first step of Example 1 (see Figure 3 ). The film thickness of each coloring layer was 0.5 μm.

[0138] · Second process

[0139] Next, an infrared ray transmitting layer 41 is formed by the same method as the second step of Example 1 except that the amount of the photosensitive material applied to the color filter 4 and the portion of the upper surface of the substrate 2 not covered by the color filter 4 is changed (see Figure 4 ). The film thickness of the obtained infrared ray transmitting layer 41 was 1.0 μm.

[0140] ·3rd process

[0141] Next, a photosensitive material similar to that used in the third step of Example 1 is applied on the infrared transmission layer 41 and the color filter 4 to form a coating film. Next, the coating film is patterned by a photolithography method including exposure and development, thereby forming an infrared shielding layer 6 on the color filter 4 so that its upper surface has a greater height than that of the infrared transmission layer 41 (see Fig. 9 ).

[0142] Fig.14 This is an electron microscope photograph of a partial structure of an image sensor according to a comparative example having the infrared shielding layer 6 obtained in the third step after exposure and development and before heat flow, taken from an oblique direction.

[0143] ·Step 4

[0144] Next, the infrared shielding layer 6 obtained in the third step is sintered to apply a heat flow. Fig. 9 The image sensor 100B shown in the figure omits the partial structure of the image sensor of the microlens array 5. Here, regarding the partial structure obtained, the film thickness of the infrared shielding layer 6 is 0.7 μm, and the difference H between the height of the upper surface of the infrared transmission layer 41 and the height of the upper surface of the infrared shielding layer 6 is D (H D =H PH -H CL ) is -0.2μm.

[0145] Fig.15 This is an electron microscope photograph taken from an oblique direction of the partial structure of the image sensor having the infrared shielding layer 6 after the heat flow obtained in the fourth step. Fig.16 It is an electron microscope photograph of the cross section of its local structure. Fig.14 By comparison, it can be confirmed that the upper surface peripheral portion of the infrared transmission layer 41 is covered with the infrared shielding layer 6 due to the heat flow through the infrared shielding layer 6. It can be inferred that the image sensor manufactured using this point is prone to color mixing.

[0146] In addition, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made in the implementation stage without departing from the main purpose thereof. In addition, the various embodiments can be appropriately combined and implemented, in which case the combined effect can be obtained. Moreover, the above-mentioned embodiments include various inventions, and various inventions can be extracted by selecting a combination from a plurality of disclosed structural elements. For example, in the case where the problem can be solved and the effect can be obtained even if several technical features are deleted from all the technical features shown in the embodiments, the structure in which the technical features are deleted can be extracted as an invention.

[0147] Description of the label

[0148] 1A…image sensor, 1B…image sensor, 2…substrate, 4…color filter, 5…microlens array, 6…infrared shielding layer, 21…photodiode, 41…infrared transmitting layer, 42…first coloring layer, 43…second coloring layer, 44…third coloring layer, 51…microlens, 100A…image sensor, 100B…image sensor, 100C…image sensor, D…first through hole.

Claims

1. An image sensor, wherein: The image sensor has: a substrate provided with a plurality of photodiodes; a color filter including a plurality of coloring layers respectively disposed on a portion of the plurality of photodiodes, and having a plurality of first through holes respectively disposed at positions of another portion of the plurality of photodiodes; an infrared shielding layer, which is disposed on the color filter, shields infrared rays of a specific wavelength and allows visible light to pass therethrough, and has a plurality of second through holes respectively connected to the plurality of first through holes; a plurality of infrared light transmitting layers which respectively fill one of the plurality of first through holes and the second through hole connected to the first through hole, shield visible light and transmit infrared light of the specific wavelength; as well as a plurality of micro lenses sandwiching the color filter, the infrared shielding layer, and the plurality of infrared transmitting layers and facing the plurality of photodiodes respectively; The entire side wall of each of the plurality of second through holes is in contact with a side surface of any one of the plurality of infrared transmitting layers. The upper surface of the infrared shielding layer has a maximum height H at a position relative to the boundary of the plurality of infrared transmitting layers. CH , and has a minimum height H at a position far from the boundary CL , The maximum height H of the upper surface of each of the plurality of infrared transmission layers PH Greater than the minimum height H CL , and is greater than or equal to the maximum height H CH .

2. The image sensor according to claim 1, wherein: The upper surface of each of the plurality of infrared transmitting layers is convex.

3. The image sensor according to claim 1, wherein: In the upper surface of the infrared shielding layer, the first regions adjacent to the second through holes are higher than the second regions adjacent to the second through holes sandwiching the first regions.

4. The image sensor according to claim 1, wherein: One or more of the colored layers in contact with the infrared-transmitting layers among the plurality of colored layers has an inverted tapered cross-sectional shape.

5. A method for manufacturing an image sensor, wherein: The manufacturing method of the image sensor comprises the following steps: A color filter including a plurality of coloring layers and having a plurality of through holes is formed in the following manner: the plurality of coloring layers are respectively provided on a portion of a plurality of photodiodes provided on a substrate, and the plurality of through holes are provided at positions of another portion of the plurality of photodiodes; forming a plurality of infrared light transmission layers that shield visible light and transmit infrared light of a specific wavelength by filling the plurality of through holes and protruding from the plurality of through holes; forming an infrared shielding layer that shields the infrared rays of the specific wavelength and transmits visible light on the color filter in such a manner that the upper surface of the infrared shielding layer has a smaller height than the plurality of infrared transmitting layers; applying a heat flow to the infrared shielding layer; and Then, a plurality of micro lenses are formed so as to sandwich the color filter, the infrared shielding layer, and the plurality of infrared transmitting layers and face the plurality of photodiodes respectively.

Images