JP2011029474A - Solid-state image sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state image sensor which has an optical waveguide having superior light harvesting properties and evenness, and can easily be manufactured. <P>SOLUTION: This solid-state image sensor 100 includes a substrate 10, a photoelectrically converting part 20 formed above the substrate 10, and an optical waveguide part 30 formed above the photoelectrically converting part 20, and the optical waveguide part 30 includes at least one kind selected from a polyamic acid represented by the formula (1) and an imidization polymer of the polyamic acid at 90 mass% or over. In the formula (1), R<SP>1</SP>indicates an alkyl or cyano group of a carbon number 1-3 independently, a indicates an integer 0-4 independently, R indicates a tetravalent organic group, n indicates an integer 1-4, and m indicates an integer 1-100,000. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device.

  A solid-state imaging device mounted on a digital camera, a mobile phone, or the like has a structure in which a plurality of light receiving units (photoelectric conversion mechanisms) such as a CCD (Charge Coupled Device) and a MOS (Metal Oxide Semiconductor) are two-dimensionally arranged. Have Such a solid-state imaging device has been required to increase the number of pixels. In other words, in the solid-state imaging device, each pixel is increasingly miniaturized. As a result, the amount of light received per unit pixel of the solid-state image sensor has become very small.

  If the amount of light received by the light receiving unit is insufficient, the quality of the captured image is degraded. For this reason, a method for increasing the amount of received light per pixel has been proposed. For example, it has been proposed to provide a lens for condensing light in the light receiving portion of a solid-state imaging device, or to provide an optical waveguide for the device. As an example of forming the optical waveguide, for example, Patent Document 1 describes that the optical waveguide is formed of a material having a high refractive index. This document discloses the use of a composite material of a highly transparent resin and metal oxide particles having a high refractive index such as titanium oxide as such a high refractive index material.

JP 2008-091744 A

  However, since the pixels of the solid-state imaging device are becoming very small, the dimensions of the optical waveguide are also becoming very small. That is, the optical waveguide has a light receiving surface with a small area and a long waveguide path (a shape with a large aspect ratio).

  Therefore, when a resin composition containing metal oxide particles as described above is used as the material of the optical waveguide, the material is uniformly distributed over the entire opening for the optical waveguide in the process of forming the optical waveguide during manufacturing. It is getting harder to fill.

  On the other hand, when the opening for the optical waveguide is designed to be large, there is a problem that irregularities derived from the opening are generated in the same process on the upper surface side of the solid-state imaging device. When the flatness of the upper surface of the optical waveguide is impaired, it is difficult to efficiently guide light to the light receiving unit, and there is a problem that the sensitivity of the solid-state imaging device is lowered.

  Further, in the manufacturing process of the solid-state imaging device, after the optical waveguide is formed, it may be etched as necessary. Even in such a case, when the resin composition containing the metal oxide particles as described above is used for the optical waveguide, there is a problem that it is difficult to increase the etching rate.

  One of the objects according to some embodiments of the present invention is to provide a solid-state imaging device that has an optical waveguide with good condensing property and flatness and is easy to manufacture.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
One aspect of the solid-state imaging device according to the present invention is:
A substrate,
A photoelectric conversion unit formed above the substrate;
An optical waveguide part formed above the photoelectric conversion part;
Including
The optical waveguide portion is formed of at least one selected from a polyamic acid represented by the following general formula (1) and an imidized polymer of the polyamic acid.

（一般式（１）中、Ｒ^１はそれぞれ独立に炭素数１〜３のアルキル基またはシアノ基を示し、ａはそれぞれ独立に０〜４の整数を示し、Ｒは４価の有機基を示し、ｎは１〜４の整数を示し、ｍは１〜１０００００の整数を示す。）

(In general formula (1), R ¹ each independently represents an alkyl group having 1 to 3 carbon atoms or a cyano group, a represents each independently an integer of 0 to 4, and R represents a tetravalent organic group. , N represents an integer of 1 to 4, and m represents an integer of 1 to 100,000.)

  In such a solid-state imaging device, the optical waveguide portion is formed of a polyamic acid represented by the general formula (1) and / or an imidized polymer thereof. Therefore, such a solid-state imaging device is easy to manufacture because it has good light condensing property to the photoelectric conversion part, flatness of the optical waveguide part, and filling property.

  In addition, in the description according to the present specification, the word “above” is formed, for example, “above” the “specific thing” (hereinafter referred to as “A”) and other specific thing (hereinafter referred to as “B”). And so on. In the description of the present specification, in the case of this example, the case where B is formed directly on A, the case where B is formed on A via another, and the upper part of A The word “upward” is used as a case where B is formed.

[Application Example 2]
In application example 1,
The material of the optical waveguide part may further include a surfactant.

[Claim 3]
In application example 1 or application example 2,
The optical waveguide portion is continuous with the upper surface of the photoelectric conversion portion, and has a shape extending upward from the upper surface,
The height of the optical waveguide portion with respect to the longest difference on the lower surface of the optical waveguide portion may be not less than 2 times and not more than 10 times.

[Application Example 4]
In any one of Application Examples 1 to 3,
The material of the optical waveguide part may not include particulate matter.

[Application Example 5]
One aspect of the method for producing a solid-state imaging device according to the present invention is as follows.
Preparing a substrate;
Forming a photoelectric conversion portion above the substrate;
Forming an interlayer insulating layer so as to cover the photoelectric conversion part;
Forming a continuous hole in the interlayer insulating layer from the upper surface of the interlayer insulating layer to the upper surface of the photoelectric conversion unit;
Filling the hole with at least one selected from a polyamic acid represented by the following general formula (1) and an imidized polymer of the polyamic acid;
including.

（一般式（１）中、Ｒ^１はそれぞれ独立に炭素数１〜３のアルキル基またはシアノ基を示し、ａはそれぞれ独立に０〜４の整数を示し、Ｒは４価の有機基を示し、ｎは１〜４の整数を示し、ｍは１〜１０００００の整数を示す。）

(In general formula (1), R ¹ each independently represents an alkyl group having 1 to 3 carbon atoms or a cyano group, a represents each independently an integer of 0 to 4, and R represents a tetravalent organic group. , N represents an integer of 1 to 4, and m represents an integer of 1 to 100,000.)

  In this way, it is possible to easily manufacture a solid-state imaging device having good light condensing property to the photoelectric conversion portion, flatness of the optical waveguide portion, and good filling properties.

[Application Example 6]
In application example 5,
The depth of the hole with respect to the difference between the openings at the top of the hole on the upper surface of the interlayer insulating layer may be not less than 2 times and not more than 10 times.

[Application Example 7]
In Application Example 5 or Application Example 6,
The hole may not be filled with particulate matter.

  In the solid-state imaging device according to the present invention, the optical waveguide portion is formed of a polyamic acid represented by the general formula (1) and / or an imidized polymer thereof. Therefore, such a solid-state imaging device is easy to manufacture because it has good light condensing property to the photoelectric conversion part, flatness of the optical waveguide part, and filling property. Moreover, according to the manufacturing method of the solid-state image sensor concerning this invention, an optical waveguide part has a process with which the polyamic acid represented by General formula (1) and / or its imidized polymer are filled. Therefore, it is possible to easily manufacture a solid-state imaging device having good light condensing property to the photoelectric conversion unit, flatness of the optical waveguide unit, and good filling property.

The schematic diagram of the cross section of the principal part of the solid-state image sensor 100 concerning embodiment. The schematic diagram which expanded the cross section of the principal part of the solid-state image sensor 100 concerning embodiment. The schematic diagram of the manufacturing process of the solid-state image sensor 100 concerning embodiment. The schematic diagram of the manufacturing process of the solid-state image sensor 100 concerning embodiment. The schematic diagram of the manufacturing process of the solid-state image sensor 100 concerning embodiment. The schematic diagram of the manufacturing process of the solid-state image sensor 100 concerning embodiment.

  Hereinafter, preferred embodiments of the present invention will be described. Embodiment described below demonstrates an example of this invention. In addition, the present invention is not limited to the following embodiments, and includes various modifications that are implemented within a range that does not change the gist of the present invention.

  Examples of the solid-state imaging device according to the present invention include a charge coupled device (CCD) and a MOS type imaging device. In the following embodiment, a solid-state imaging device 100 including a CCD is illustrated.

1. Solid-State Imaging Device FIG. 1 is a schematic diagram of a cross-section of a main part of a solid-state imaging device 100 according to an embodiment. FIG. 2 is an enlarged schematic view of the cross section of the main part of the solid-state imaging device 100.

  The solid-state imaging device 100 according to the present embodiment includes a substrate 10, a photoelectric conversion unit 20, and an optical waveguide unit 30.

1.1. Substrate The substrate 10 serves as a base of the solid-state image sensor 100. The substrate 10 has a flat shape, a film shape, a sheet shape, or the like. The substrate 10 may be a stacked body of a plurality of substrates. The substrate 10 may be configured including, for example, a semiconductor substrate or a wiring substrate. A photoelectric conversion unit 20 (described later), a register, and the like can be formed on the substrate 10. The substrate 10 may have a transistor (for example, TFT), a control IC, a wiring layer, and the like. FIG. 1 illustrates an example in which the photoelectric conversion unit 20 is formed on the substrate 10.

  The material of the substrate 10 is not particularly limited, and may be an inorganic material such as metal, glass, silicon, or gallium arsenide, or a polymer material such as (meth) acrylic resin, polyimide resin, alicyclic olefin resin, or polycarbonate. Can do. The first substrate 10 may be a stack of a plurality of different materials. For example, the substrate 10 may include a reflective layer that reflects light. If the substrate 10 is a semiconductor substrate such as a silicon substrate or a GaAs substrate, the photoelectric conversion unit 20 can be easily formed in the substrate 10.

1.2. Photoelectric Conversion Unit The photoelectric conversion unit 20 is formed above the substrate 10. The photoelectric conversion unit 20 may be formed so as to be embedded in the upper surface of the substrate 10. In the solid-state imaging device 100 of the present embodiment, the photoelectric conversion unit 20 is formed on the upper surface side of the substrate 10.

  The shape of the photoelectric conversion unit 20 is not particularly limited, and may be an oval, a circle, a rectangle, a square, or the like in plan view. The size of the photoelectric conversion unit 20 in plan view can be appropriately selected according to the design such as the resolution of the solid-state imaging device 100. For example, the length of one side in a square shape is 100 nm or more and 10 μm or less. it can. A plurality of photoelectric conversion units 100 can be formed on the substrate 10. The number of photoelectric conversion units 100 formed on the substrate 10 is appropriately selected according to the design such as the resolution of the solid-state imaging device 100 and is not particularly limited. Moreover, the thickness etc. of the photoelectric conversion part 20 are not specifically limited.

  The photoelectric conversion unit 20 is a part (photosensor) that converts light into an electrical signal, and a known photoelectric conversion element, for example, a photodiode can be applied. The photoelectric conversion unit 20 can be configured by, for example, a pn junction in which a substrate 10 is a semiconductor substrate and regions having different conductivity types are formed on the surface thereof. Further, the photoelectric conversion unit 20 may be formed including other components such as a register.

  The wavelength range of the electromagnetic wave (light) detected by the photoelectric conversion unit 20 is not particularly limited, but is, for example, in the range of 300 nm to 1100 nm. The photoelectric conversion unit 20 can typically detect visible light and convert it into an electrical signal.

1.3. Optical waveguide section 1.3.1. Shape of Optical Waveguide Part, etc. The optical waveguide part 30 is formed above the photoelectric conversion part 20. The optical waveguide unit 30 may be formed continuously with the photoelectric conversion unit 20. Further, the optical waveguide unit 30 may be connected to the photoelectric conversion unit 20 via another member (for example, an optical member such as a lens). One of the functions of the optical waveguide unit 30 is to collect light incident on the solid-state imaging device 100 with respect to the photoelectric conversion unit 20. For this reason, the optical waveguide portion 30 is formed of a material having a higher refractive index than other adjacent members. As a result, light can be confined in the optical waveguide section 30 and the light collection efficiency on the photoelectric conversion section 20 can be further increased. Details of the material of the solid-state imaging device 100 of the present embodiment will be described later.

  The optical waveguide unit 30 is provided corresponding to each photoelectric conversion unit 20. The shape of the optical waveguide portion 30 is not particularly limited, and can be, for example, a cylindrical shape, a prismatic shape, a truncated cone, a truncated pyramid, or the like. In the example of FIG. 1, the optical waveguide portion 30 has a truncated cone shape that is smaller in size on the photoelectric conversion portion 20 side. Furthermore, the upper surface or the lower surface of the optical waveguide portion 30 may have a convex shape or a concave shape. In this way, the function of an optical lens can be imparted to the optical waveguide portion 30. The uneven shape in this case can be freely designed in consideration of the optical path of incident light.

  It is more preferable that the optical waveguide unit 30 has a shape that is continuous with the upper surface of the photoelectric conversion unit 20 and extends upward from the upper surface. In this way, it becomes easier to collect the light incident from the outside of the solid-state imaging device 100 on the photoelectric conversion unit 20. In this way, the photoelectric conversion units 20 can be more densely arranged in the solid-state imaging device 100. That is, the resolution of the solid-state imaging device 100 (the planar density of the photoelectric conversion unit 20) can be further increased.

  It is more preferable that the height of the optical waveguide portion 30 with respect to the longest difference between the optical waveguide portion 30 and the lower surface of the optical waveguide portion 30 is not less than 2 times and not more than 10 times. Here, the longest difference corresponds to the radius when the lower surface is a circle when the lower surface of the optical waveguide portion 30 is viewed in a plane, and corresponds to the major axis when the lower surface is an ellipse. Further, the longest difference is that when the lower surface of the optical waveguide portion 30 is viewed in a plane, it corresponds to one of the diagonal lines if the lower surface is rectangular, and a specific point on the outer periphery if it is indefinite. This corresponds to the largest distance among the distances from one point to the opposite point. The height of the optical waveguide unit 30 refers to the distance from the end of the optical waveguide unit 30 on the substrate 10 side to the opposite (upper) end. By making the optical waveguide part 30 into such a shape, for example, light incident from the outside of the solid-state imaging device 100 can be more easily collected on the photoelectric conversion part 20.

  The optical waveguide unit 30 may be disposed alone as long as it is disposed above the photoelectric conversion unit 20, but, for example, an interlayer formed above the substrate 10 as in the solid-state imaging device 100 of the present embodiment. A hole 42 may be provided in the insulating layer 40, and the optical waveguide portion 30 may be formed inside the hole 42 (see FIG. 2). In this way, for example, the manufacture of the optical waveguide part 30 can be facilitated.

The refractive index of the optical waveguide portion 30 is preferably sufficiently higher than the surrounding refractive index. In the case of forming the interlayer insulating layer 40, in order to increase the light collection efficiency to the photoelectric conversion unit 20, as the material of the interlayer insulating layer 40, SiO ₂ having a refractive index of about 1.4 to 1.5 or a refractive index Formed with SiO ₂ materials such as BPSG (borophosphosilicate glass), PSG (phosphosilicate glass), SOG (spin-on-glass), and SiON (silicon oxynitride) materials with a thickness of about 1.4 to 1.5 It is preferred that In the case where the optical waveguide portion 30 is formed using the interlayer insulating layer 40 and the interlayer insulating layer 40 is formed of silicon oxide (SiO ₂ ), for example, a thermal oxidation method or CVD (Chemical Vapor Deposition) is used. ) Method or the like.

  Further, the solid-state imaging device 100 of the present embodiment may include an on-chip lens 50 for condensing light on the optical waveguide unit 30, as shown in FIG. In the illustrated example, the on-chip lens 50 is provided above the optical waveguide portion 30, but may be provided below. A plurality of on-chip lenses 50 may be provided.

1.3.2. Material of Optical Waveguide Portion, etc. The optical waveguide portion 30 is formed of at least one selected from polyamic acid represented by the following general formula (1) and an imidized polymer of the polyamic acid.

（上記一般式（１）中、Ｒ^１はそれぞれ独立に炭素数１〜３のアルキル基またはシアノ基を示し、ａはそれぞれ独立に０〜４の整数を示し、Ｒは４価の有機基を示し、ｎは１〜４の整数を示し、ｍは１〜１０００００の整数を示す。）

(In the general formula (1), each R ¹ independently represents an alkyl group having 1 to 3 carbon atoms or a cyano group, each a independently represents an integer of 0 to 4, and R represents a tetravalent organic group. N represents an integer of 1 to 4, and m represents an integer of 1 to 100,000.)

  The polyamic acid having the structure represented by the general formula (1) has a high refractive index (25 ° C., wavelength 400 to 700 nm), and is excellent in transparency and heat resistance. Similarly, the imidized polymer of the polyamic acid has a high refractive index (25 ° C., wavelength 400 to 700 nm) and is excellent in transparency and heat resistance. .

In General Formula (1), R ¹ independently represents an alkyl group having 1 to 3 carbon atoms or a cyano group, a represents the number of substitutions of the group R ¹ , and represents an integer of 0 to 4. It is preferred that a is 0 (ie, no substituent) or R ¹ is a cyano group and a is 1. R represents a tetravalent organic group, and specifically corresponds to a residue obtained by removing an anhydride group from an aliphatic, alicyclic or aromatic tetracarboxylic dianhydride, and the resulting polymer has transparency. It is preferable that it is a residue of an alicyclic tetracarboxylic dianhydride or an aliphatic tetracarboxylic dianhydride at the point which raises more. R preferably contains a sulfur atom since a high refractive index can be obtained. n shows the integer of 1-4 and it is preferable that it is an integer of 2-4. m represents an integer of 1 to 100,000, and is preferably an integer of 10 to 10,000.

  The polyamic acid having the structure represented by the general formula (1) can be produced, for example, as follows. The polyamic acid having the structure represented by the general formula (1) is obtained, for example, by reacting a diamine represented by the following general formula (2) with a tetracarboxylic acid dianhydride represented by the following general formula (3). be able to.

In the general formula (2) and the general formula (3), R ¹ , R, a, and n are as described in the general formula (1), and thus the description thereof is omitted.

  Examples of the diamine represented by the general formula (2) include 4,4 ′-(p-phenylenedisulfanyl) dianiline, 1,3-bis (4-aminophenylsulfanyl) benzene, 1,3-bis ( 4-aminophenolsulfanyl) 5-cyanobenzene, 4,4′-thiobis [(p-phenylenesulfanyl) aniline], 4,4′-bis (4-aminophenylsulfanyl) -p-dithiophenoxybenzene and the like. Of these, 4,4′-thiobis [(p-phenylenesulfanyl) aniline] and the like are more preferable.

  In addition, the optical waveguide part 30 may contain polyamic acid other than the polyamic acid which has a structure shown by the said General formula (1). That is, in addition to the diamine represented by the general formula (2), a diamine not containing a sulfur atom may be used in combination. Further, examples of diamines that can be used in combination include p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylethane, 4,4′-diaminodiphenyl sulfide, 4, 4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 3,3-dimethyl-4,4'-diaminobiphenyl, 4,4'-diaminobenzanilide, 3,4'- Diaminodiphenyl ether, 3,3′-diaminobenzophenone, 3,4′-diaminobenzophenone, 4,4′-diaminobenzophenone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-Aminophenoxy) phenyl] hexafluoropropyl Pan, 2,2-bis (4-aminophenyl) hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] sulfone, 1,4-bis (4-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 9,9-bis (4-aminophenyl) -10-hydroanthracene, 9,9-bis (4-amino) Phenyl) fluorene, 4,4′-methylene-bis (2-chloroaniline), 2,2 ′, 5,5′-tetrachloro-4,4′-diaminobiphenyl, 2,2′-dichloro-4,4 '-Diamino-5,5'-dimethoxybiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 4,4'-(p-phenylenediisopropylidene) bisaniline , 4,4 ′-(m-phenylenediisopropylidene) bisaniline, aromatic diamine having a heteroatom such as diaminotetraphenylthiophene; 1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, Pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro- Mention may be made of aliphatic or alicyclic diamines such as 4,7-methanoindanylene methylenediamine and tricyclo [6,2,1,02.7] -undecylenedimethyldiamine.

  Of the diamines used for producing the polyamic acid of the general formula (1), the proportion of the diamine represented by the general formula (2) is preferably 50 mol% or more, more preferably 80 mol% or more. In order to obtain a sufficient refractive index, the content is preferably 100 mol%.

  In general formula (3), R corresponds to a residue obtained by removing an anhydride group from tetracarboxylic dianhydride. Such compounds include aliphatic, alicyclic or aromatic tetracarboxylic dianhydrides, and the resulting polymer has excellent transparency, so that aliphatic and alicyclic tetracarboxylic dianhydrides. Anhydrides are preferred.

  Examples of aliphatic and alicyclic tetracarboxylic dianhydrides include, for example, butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4 -Cyclopentanetetracarboxylic dianhydride, 4,10-dioxatricyclo [6.3.1.02,7] dodecane-3,5,9,11-tetraone, 1,2,4,5-cyclohexane Tetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dihydrate, 3,5,6-tricarboxynorbornane-2-acetic acid dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic Acid dianhydride, 1,3,3a, 4,5,9b-hexahydro-5-tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, bicyclo [2,2,2] -oct-7-ene-2,3 Mention may be made of aliphatic and alicyclic tetracarboxylic dianhydrides such as 5,6-tetracarboxylic dianhydride. Among these, butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 4,10-dioxatricyclo [6.3.1.02,7] dodecane-3 , 5,9,11-tetraone, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid Dianhydride and 1,3,3a, 4,5,9b-hexahydro-5-tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione More preferably, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 4,10-dioxatricyclo [6.3.1.02,7] dodecane-3,5,9,11-tetraone, 1, 2, 4 5-cyclohexane tetracarboxylic acid dianhydride are particularly preferred.

  Specific examples of the aromatic tetracarboxylic dianhydride include, for example, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4 ′. -Biphenylsulfone tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3 ', 4,4 '-Biphenyl ether tetracarboxylic dianhydride, 3,3', 4,4'-dimethyldiphenylsilane tetracarboxylic dianhydride, 3,3 ', 4,4'-tetraphenylsilane tetracarboxylic dianhydride 1,2,3,4-furantetracarboxylic dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, 4,4′-bis (3,4-dical) Xylphenoxy) diphenylsulfone dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 4,4 ′-(hexafluoroisopropylidene) bis (phthalic acid) dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenylphosphine oxide dianhydride, p-phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis Aromatic tetra such as (triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4′-diphenyl ether dianhydride, bis (triphenylphthalic acid) -4,4′-diphenylmethane dianhydride Carboxylic dianhydrides can be mentioned. Among these, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic dianhydride, 4 4,4 ′-(hexafluoroisopropylidene) bis (phthalic acid) dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride are more preferred.

  Moreover, since the polyamic acid of a higher refractive index is obtained, it is also preferable to use the tetracarboxylic dianhydride containing a sulfur atom. Examples of the sulfur atom-containing acid anhydride include 4,4 '-[p-thiobis (phenylene-sulfanyl)] diphthalic acid anhydride.

  The reaction of the diamine represented by the general formula (2) and the tetracarboxylic dianhydride represented by the general formula (3) can be performed in an aprotic organic solvent such as N-methyl-2-pyrrolidone. A polyamic acid of the general formula (1) can be obtained by stirring and mixing the diamine compound and the acid dianhydride. Further, for example, a diamine compound may be dissolved in an organic solvent, and acid dianhydride may be added thereto and mixed with stirring. A mixture of a diamine compound and acid dianhydride may be added to an organic solvent and mixed with stirring. May be. The reaction is usually performed at a temperature of 100 ° C. or lower, preferably 80 ° C. or lower, under normal pressure. However, the reaction may be performed under pressure or under reduced pressure as necessary. The reaction time varies depending on the diamine compound and acid dianhydride used, the organic solvent, the reaction temperature, etc., but is usually in the range of 4 to 24 hours.

  The optical waveguide unit 30 may contain an additive such as a surfactant. For example, in the manufacture of the solid-state imaging device 100, the surfactant can be added to form a uniform coating film when the optical waveguide portion 30 is formed by applying the above-described material by spin coating. .

  Examples of the surfactant that may be blended in the optical waveguide unit 30 include polydimethylsiloxane surfactants, fluorine surfactants, and the like, and polydimethylsiloxane surfactants. Examples of polydimethylsiloxane-based surfactants include, for example, SH28PA (Toray Dow Corning, dimethylpolysiloxane polyoxyalkylene copolymer), Paintad 19, 54 (Toray Dow Corning, dimethylpolysiloxane polyoxy). Alkylene copolymer), FM0411 (silaplane, manufactured by Chisso), SF8428 (manufactured by Toray Dow Corning, dimethylpolysiloxane polyoxyalkylene copolymer (containing side chain OH)), BYK UV3510 (manufactured by BYK Japan, Dimethylpolysiloxane-polyoxyalkylene copolymer), DC57 (manufactured by Toray Dow Corning Silicone, dimethylpolysiloxane-polyoxyalkylene copolymer), DC190 (manufactured by Toray Dow Corning Silicone, Methylpolysiloxane-polyoxyalkylene copolymer), Silaplane FM-4411, FM-4421, FM-4425, FM-7711, FM-7721, FM-7725, FM-0411, FM-0421, FM-0425, FM-DA11, FM-DA21, FM-DA26, FM0711, FM0721, FM-0725, TM-0701, TM-0701T (manufactured by Chisso), UV3500, UV3510, UV3530 (manufactured by Big Chemie Japan), BY16-004, SF8428 (made by Toray Dow Corning Silicone), VPS-1001 (made by Wako Pure Chemical Industries), etc. are mentioned. In particular, Silaplane FM-7711, FM-7721, FM-7725, FM-0411, FM-0421, FM-0425, FM0711, FM0721, FM-0725, VPS-1001, etc. can be mentioned. Moreover, as a commercial item of the said silicone compound which has an ethylenically unsaturated group, Tego Rad2300, 2200N, Tego Chemie, etc. can be mentioned, for example.

  Examples of the fluorosurfactant include, for example, MegaFuck F-114, F410, F411, F450, F493, F494, F443, F444, F445, F446, F470, F471, F472SF, F474, F475, R30, F477. F478, F479, F480SF, F482, F483, F484, F486, F487, F553, F172D, F178K, F178RM, ESM-1, MCF350SF, BL20, R08, R61, R90 (manufactured by Dainippon Ink & Chemicals, Inc.) .

  The compounding amount of the surfactant in the optical waveguide part 30 is usually 0 to 10% by mass, preferably 0.1 to 5% by mass, more preferably 0.5 to 3% when the total solid content is 100% by mass. It is in the range of mass%. When the compounding amount of the surfactant exceeds 10% by mass, the refractive index may decrease.

  In the solid-state imaging device 100 of the present embodiment, the optical waveguide unit 30 is formed of the above-described compound. Therefore, the refractive index of the optical waveguide part 30 is sufficiently high (the refractive index at a wavelength of 633 nm is 1.76 at the maximum).

  The optical waveguide portion 30 preferably has a particulate matter content of 10% by mass or less, more preferably 5% by mass or less, and particularly preferably no particulate matter. The particulate material refers to, for example, an insoluble or infusible material such as metal oxide particles. By not containing such a particulate material in the optical waveguide portion 30, it is possible to make it difficult for defects or the like to occur in the optical waveguide portion 30. The defect in this case refers to, for example, the structural nonuniformity such as voids and the distribution of the characteristic value such as the refractive index in the optical waveguide portion 30.

1.4. Other Configurations The solid-state imaging device 100 according to the present embodiment can further include various other members. For example, the solid-state imaging device 100 may include an in-layer lens, a transfer electrode, a light shielding film, a color filter, a planarization layer, an antireflection film, and the like.

1.5. Operational Effect In the solid-state imaging device 100 according to the present embodiment, the optical waveguide portion 30 is formed of the polyamic acid represented by the general formula (1) and / or its imidized polymer. Therefore, the solid-state imaging device 100 is excellent in the light condensing property to the photoelectric conversion unit 20. Furthermore, when the solid-state imaging device 100 according to the present embodiment does not include a particulate substance in the optical waveguide portion 30, the flatness, filling property, and uniformity of the optical waveguide portion 30 are good and easy to manufacture.

2. Manufacturing Method of Solid-State Image Sensor FIG. 3 to FIG. 6 are schematic diagrams of the manufacturing process of the solid-state image sensor 100 of this embodiment.

  The method of manufacturing a solid-state imaging device according to the present invention includes a step of preparing a substrate, a step of forming a photoelectric conversion unit, a step of forming an interlayer insulating layer, a step of forming a hole in the interlayer insulating layer, Filling the hole with at least one selected from a polyamic acid represented by the following general formula (1) and an imidized polymer of the polyamic acid.

（一般式（１）中、Ｒ^１はそれぞれ独立に炭素数１〜３のアルキル基またはシアノ基を示し、ａはそれぞれ独立に０〜４の整数を示し、Ｒは４価の有機基を示し、ｎは１〜４の整数を示し、ｍは１〜１０００００の整数を示す。）

(In general formula (1), R ¹ each independently represents an alkyl group having 1 to 3 carbon atoms or a cyano group, a represents each independently an integer of 0 to 4, and R represents a tetravalent organic group. , N represents an integer of 1 to 4, and m represents an integer of 1 to 100,000.)

  Hereinafter, although each process is explained in full detail, in description of the above-mentioned solid-state image sensor 100, about the member described, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  First, as shown in FIG. 3, the substrate 10 is prepared, and the photoelectric conversion unit 20 is formed above (upper surface) of the substrate 10. The photoelectric conversion unit 20 can be formed by a known method, for example, by doping the substrate 10 with impurities. Moreover, a charge transfer part etc. can be formed as needed simultaneously with or before or after the formation of the photoelectric conversion part 20. Further, after the photoelectric conversion unit 20 is formed, a transfer electrode, an antireflection film, and a light shielding film may be formed as necessary. Further, an insulating film other than the interlayer insulating layer 40 may be formed.

  Next, as illustrated in FIG. 3, an interlayer insulating layer 40 a is formed so as to cover the photoelectric conversion unit 20. The interlayer insulating layer 40 a may be formed to cover the photoelectric conversion unit 20 and the substrate 10. In the illustrated example, the interlayer insulating layer 40 a is formed to cover the photoelectric conversion unit 20 and the substrate 10. The interlayer insulating layer 40 can be formed by, for example, a spin coating method, a CVD method, or the like.

  Next, as illustrated in FIG. 4, a hole 42 is formed in the interlayer insulating layer 40 a so as to continue from the upper surface of the interlayer insulating layer 40 a to the upper surface of the photoelectric conversion unit 20. By this step, the interlayer insulating layer 40 is formed at the same time. The hole 42 has a shape corresponding to the outer shape of the optical waveguide portion 30. The hole 42 is formed above the photoelectric conversion unit 20. In this embodiment, the hole 42 is formed through the interlayer insulating layer 40 so as to reach the photoelectric conversion unit 20, but is formed in the interlayer insulating layer 40 so as not to reach the photoelectric conversion unit 20. It may be a recess. The hole 42 can be formed by photolithography or the like using an appropriate mask and etchant. The hole 42 can also be formed by a known method such as anisotropic dry etching or reactive dry etching.

  Next, as shown in FIG. 5, the hole 42 is filled with at least one selected from the polyamic acid represented by the general formula (1) and an imidized polymer of the polyamic acid, and the optical waveguide portion 30a is formed. Form. Specifically, in this step, a method such as application using a liquid injection nozzle such as a dispenser, spray application such as an ink jet method, application by rotation such as spin coating, application by squeezing such as printing, or transfer may be used. it can.

  In this step, in order to adjust the viscosity of the raw material liquid during spin coating, the compound represented by the general formula (1) may be dissolved and applied in an appropriate organic solvent. Examples of the organic solvent at this time include an aprotic organic solvent. As the aprotic organic solvent, for example, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), cyclohexanone, N, N-dimethylacetamide (DMAc) and the like are preferable. Besides these, N, N-dimethylformamide, N, N-diethylacetamide, N, N-dimethoxyacetamide, 1,3-dimethyl-2-imidazolidinone, N-methylcaprolactam, 1,2-dimethoxyethane, 1 , 2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, bis [2- (2-methoxyethoxy) ethyl] ether, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, pyrroline, picoline, dimethyl sulfoxide, dimethyl sulfone, tetramethyl urea, hexamethyl phosphoramide, propylene glycol monomethyl ether (PGMME), γ-butyrolactone (GBL), phenol, o-cresol, m-cresol P-cresol, - cresylic acid, p- chlorophenol, mention may be made of anisole, benzene, toluene, and xylene. These organic solvents can be used alone or as a mixture of two or more.

  The amount of the organic solvent added to the compound represented by the general formula (1) in this step is usually 100 to 9900 parts by weight, preferably 100 parts by weight of the compound represented by the general formula (1). It is 300-1900 weight part, More preferably, it exists in the range of 400-1900 weight part. If the blending amount of the organic solvent is less than 100 parts by weight, spin coating may not be possible, and if it exceeds 9900 parts by weight, the required film thickness may not be expressed. In addition, the solvent derived from manufacture of the compound represented by General formula (1) is included in the compounding quantity of an organic solvent. When the above-mentioned organic solvent is used, it may include a step of removing the solvent after applying the coating liquid as necessary.

  Furthermore, at this process, the imidation catalyst for hardening the compound represented by General formula (1) by heating can also be added to a coating liquid. As an imidation catalyst, an acetic anhydride-pyridine mixed solution etc. are mentioned, for example. Moreover, an acetic anhydride-triethylamine mixed solution, trifluoroacetic anhydride, and dicyclohexylcarbodiimide can also be used. Moreover, the optical waveguide part 30 can be made into the material which can be patterned by using the photo-acid generator or photobase generator which is a compound which generate | occur | produces an acid or a base by irradiation of light as an imidation catalyst. Examples of the photobase generator include carbamate type photobase generators. The amount of the imidization catalyst is in the range of 0 to 20% by mass, preferably 1 to 10% by mass, more preferably 1 to 5% by mass, when the optical waveguide portion 30 is 100% by mass. When the above-mentioned imidation catalyst is used, a step of performing a curing treatment can be added as necessary. The curing process can be, for example, photocuring or heat curing.

  Further, in this step, a thermosetting compound and a photocurable compound can be added. By blending these compounds, the hardness of the obtained optical waveguide portion 30 can be increased. Examples of the thermosetting compound include melamine compounds and alkoxysilanes. Examples of the photocurable compound include a compound having a (meth) acryloyl group, a compound having a vinyl group, and the like.

  In this step, it is preferable that no particulate matter is added to the compound represented by the general formula (1). In this case, the hole 42 is filled without gaps by coating using a liquid injection nozzle such as a dispenser, spray coating such as an ink jet method, coating by rotation such as spin coating, coating by squeezing such as printing, or transfer. Is even easier. In this way, in particular, when the depth of the hole 42 with respect to the difference in opening of the hole 42 is 2 times or more and 10 times or less, the hole 42 can be easily filled without a gap.

  Thereafter, as shown in FIG. 6, a step of removing the optical waveguide portion 30a formed on the interlayer insulating layer 40 can be performed as necessary. This step can be performed by dry etching, wet etching, or the like. In the case where this step is performed, when no particulate matter is added to the compound represented by the general formula (1), the etching rate of dry etching, wet etching, or the like can be sufficiently increased.

  Next, for example, by providing a separately prepared microlens array above the interlayer insulating layer 40, the solid-state imaging device 100 of this embodiment shown in FIG. 1 can be obtained.

  According to the method for manufacturing a solid-state imaging device of the present embodiment, it is possible to easily manufacture a solid-state imaging device that has good condensing property to the photoelectric conversion unit, flatness of the optical waveguide unit, and filling property.

3. Examples and Comparative Examples Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the scope of the present invention.

  In Examples and Comparative Examples, the embedding property of the compound represented by the general formula (1) into the hole was evaluated. That is, the composition of each example was apply | coated with respect to the following base material, and the various shapes after drying were evaluated.

3.1. As the substrate 10, a silicon substrate was used. A SiO ₂ film having a thickness of 3 μm was formed on the upper surface of the silicon substrate by spin coating and baked. Then, the SiO ₂ film was etched to form a hole (through hole reaching the silicon substrate) having an opening diameter of 0.8 μm and a depth of 3 μm.

3.2. Compositions Compositions of Examples and Comparative Examples shown in Table 1 were prepared.

  In Table 1, P-1 is BT-100 (1,2,3,4-butanetetracarboxylic dianhydride manufactured by Shin Nippon Chemical Co., Ltd.) as an acid dianhydride, and 3SDA (4,4) as a diamine. A compound synthesized using '-thiobis [(p-phenylenesulfanyl) aniline]) is shown.

  P-1 is the following compound. In a reaction vessel equipped with a nitrogen introduction tube, dimethylacetamide (30 g) (hereinafter referred to as DMAc) was added to 3SDA (11.88 g, 27.46 mmol), and the mixture was stirred at room temperature for complete dissolution. Next, BT-100 (5.45 g, 27.50 mmol) and DMAc (10 g) were added, and the mixture was stirred at 40 ° C. for 4 hours. Next, after adding DMAc (110 g), acetic anhydride (2.81 g) and pyridine (2.18 g) were added as imidation catalysts, and the mixture was stirred at 110 ° C. for 5 hours to obtain a DMAc solution of P-1. . A predetermined amount of DMAc was removed by a vacuum distillation method to obtain a solution having a solid content concentration of 20%, and then a predetermined amount of γ-butyrolactone (hereinafter referred to as GBL) was added to obtain a solution having a solid content concentration of 10%. After this operation was repeated twice, the solid content concentration was again adjusted to 25% by a vacuum distillation method to obtain a P-1 GBL solution. The imidation ratio of P-1 was 50%.

  In Table 1, P-2 indicates a compound synthesized by using SDA (4,4′-thiodianiline instead of 3SDA as a diamine. For P-2, SDA (9.04 g, 41.84 mmol) is used. A PBL GBL solution was obtained in the same manner as P-1, except that BT-100 (8.29 g, 41.84 mmol) was used, and the imidization ratio of P-2 was 50%.

  Experimental Examples 1 and 2 do not contain a particulate material, and Experimental Examples 3 and 4 include a silicon oxide-coated tin oxide-containing rutile titanium oxide (particle diameter of 5 to 15 nm) (particularly titanium oxide in the table). System particles). In addition, as surfactants, Experimental Examples 1 and 2 contain Megafac F-553 (manufactured by Dainippon Ink & Chemicals, Inc.), and Experimental Examples 3 and 4 are dimethylpolysiloxane-polyoxyalkylene copolymers. (DC-190, manufactured by Toray Dow Corning Silicone).

  Moreover, as shown in Table 1, the composition of each Example and each Comparative Example contains a mixed solvent of propylene glycol monomethyl ether (PGMME) and γ-butyrolactone (GBL).

  The composition of each example and each comparative example is a mixture of these compounds in the formulation shown in Table 1.

3.3. Evaluation Sample The composition of each Example and each Comparative Example was applied to the prepared substrate by a spin coat method under the condition that the film thickness of the portion other than the hole was 0.6 μm, and dried to evaluate the sample. It was.

3.4. Evaluation of embedding property The cross section of the evaluation sample of each Example and each Comparative Example was observed with a scanning electron microscope (SEM). The height (t1) of the coating film in the region where no hole was formed in the substrate and the height (t2) from the substrate surface in the region of the hole were measured. The results are shown in Table 1 with ◯ when t1> 0.6 μm and (t2 / t1)> 0.8, and x when none of these relationships are satisfied.

3.5. Evaluation of etching processability The evaluation samples of each Example and each Comparative Example were dry-etched to obtain an etching rate. The dry etching conditions were O ₂ plasma for 60 seconds and CF ₃ plasma for 8 seconds. Table 1 shows the case where the obtained etching rate was 200 (nm / min) or more, and the case where it was less than 100 (nm / min) as x.

3.6. Evaluation Results In Examples 1 and 2, both the embedding property and the etching property were good. In Comparative Example 1 and Comparative Example 2, the embedding property was poor and the etching property was in an allowable range. In each example and each comparative example, no voids were observed.

  From the above embodiments, according to the method for manufacturing a solid-state imaging device of the present invention, it is possible to easily manufacture a solid-state imaging device with good condensing property to a photoelectric conversion unit, flatness of an optical waveguide unit, and good filling properties. I found out that

  The solid-state imaging device of the present invention can be applied to various uses such as a digital camera, a video camera, a camera-equipped mobile phone, a scanner, a digital copying machine, and a facsimile. In addition, according to the method for manufacturing a solid-state imaging device of the present invention, a solid-state imaging device with excellent flatness and fillability of the optical waveguide portion can be easily manufactured.

DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 20 ... Photoelectric conversion part, 30, 30a ... Optical waveguide part, 40, 40a ... Interlayer insulation layer, 42 ... Hole, 50 ... On-chip lens, 100 ... Solid-state image sensor

Claims (8)

A substrate,
A photoelectric conversion unit formed above the substrate;
An optical waveguide part formed above the photoelectric conversion part;
Including
The said optical waveguide part is a solid-state image sensor containing 90 mass% or more of at least 1 type selected from the polyamic acid represented by following General formula (1), and the imidation polymer of this polyamic acid.

(In general formula (1), R ¹ each independently represents an alkyl group having 1 to 3 carbon atoms or a cyano group, a represents each independently an integer of 0 to 4, and R represents a tetravalent organic group. , N represents an integer of 1 to 4, and m represents an integer of 1 to 100,000.) In claim 1,
The material of the said optical waveguide part is a solid-state image sensor further containing surfactant. In claim 1 or claim 2,
The optical waveguide portion is continuous with the upper surface of the photoelectric conversion portion, and has a shape extending upward from the upper surface,
The solid-state imaging device, wherein the height of the optical waveguide portion with respect to the longest difference on the lower surface of the optical waveguide portion is not less than 2 times and not more than 10 times. In any one of Claims 1 to 3,
The material of the optical waveguide part is a solid-state imaging device in which the content of particulate matter is 10% by mass or less. Preparing a substrate;
Forming a photoelectric conversion portion above the substrate;
Forming an interlayer insulating layer so as to cover the photoelectric conversion part;
Forming a continuous hole in the interlayer insulating layer from the upper surface of the interlayer insulating layer to the upper surface of the photoelectric conversion unit;
Filling the hole with at least one selected from a polyamic acid represented by the following general formula (1) and an imidized polymer of the polyamic acid;
The manufacturing method of a solid-state image sensor containing this.

(In general formula (1), R ¹ each independently represents an alkyl group having 1 to 3 carbon atoms or a cyano group, a represents each independently an integer of 0 to 4, and R represents a tetravalent organic group. , N represents an integer of 1 to 4, and m represents an integer of 1 to 100,000.) In claim 5,
The method of manufacturing a solid-state imaging device, wherein the depth of the hole with respect to the difference in opening of the hole on the upper surface of the interlayer insulating layer is not less than 2 times and not more than 10 times. In claim 5 or claim 6,
A method for manufacturing a solid-state imaging device, wherein the hole is not filled with a particulate matter. A composition for forming a waveguide of a solid-state imaging device, containing 90% by mass or more of at least one selected from a polyamic acid represented by the following general formula (1) and an imidized polymer of the polyamic acid.

(In general formula (1), R ¹ each independently represents an alkyl group having 1 to 3 carbon atoms or a cyano group, a represents each independently an integer of 0 to 4, and R represents a tetravalent organic group. , N represents an integer of 1 to 4, and m represents an integer of 1 to 100,000.)

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