JPWO2020066127A1 - Solid-state image sensor - Google Patents

Abstract

A photoelectric conversion unit that performs photoelectric conversion according to incident light, a microlens that collects the incident light in the photoelectric conversion unit, a resin (A) containing a silicon atom and an aromatic ring on the microlens, and a radiation-sensitive compound. A solid-state image sensor having a cured film formed from a radiation-sensitive composition containing (B).

Description

The present invention relates to a solid-state image sensor.

An image sensor such as a digital camera is equipped with a solid-state image sensor such as a CCD (Charge Coupled Device) image sensor and a CMOS (Complementary Metal Oxide Semiconductor) image sensor. The solid-state image sensor has a very wide wavelength sensitivity from visible light that can be recognized by the human eye to an infrared light region having a longer wavelength.

The solid-state image sensor has a microlens. As the resolution of the solid-state image sensor increases, there is a problem that the amount of light received by the photoelectric conversion unit decreases. The cause is that the incident light is reflected on the surface of the microlens that collects the incident light, and the amount of light received by the photoelectric conversion unit is reduced. To solve this problem, for example, Patent Document 1 describes that a layer made of an acrylic resin or a fluorine-based acrylic resin is provided on the surface of a microlens.

JP-A-2007-053153

In the configuration described in Patent Document 1, since the heat resistance of the layer made of an acrylic resin or a fluorine-based acrylic resin is low, the transparency of the layer tends to decrease in a high temperature environment.

An object of the present invention is to provide a solid-state image sensor having a layer having excellent heat resistance and transparency on a microlens.

The present inventors have conducted diligent studies to solve the above problems. As a result, they have found that the above-mentioned problems can be solved by a solid-state image sensor having the following configuration, and have completed the present invention.

The present invention relates to, for example, the following [1] to [9].

[1] Feeling of a photoelectric conversion unit that performs photoelectric conversion according to incident light, a microlens that collects the incident light in the photoelectric conversion unit, and a resin (A) containing a silicon atom and an aromatic ring on the microlens. A solid-state image sensor having a cured film formed of a radiation-sensitive composition containing a radioactive compound (B).

[2] A structural unit (I) in which a resin (A) containing a silicon atom and an aromatic ring contains an aromatic ring and an alkoxysilyl group directly bonded to the aromatic ring in the same or different polymer, and an acidic group. The solid-state imaging device according to the above [1], which is a polymer component (a) having a structural unit (II) containing.

[3] Crosslinkability in a polymer in which the polymer component (a) is the same as or different from a polymer having at least one structural unit selected from the structural unit (I) and the structural unit (II). The solid-state imaging device according to the above [2], which further has a structural unit (III) including a group.

[4] The structural unit (I) is a substituted or unsubstituted benzene ring, a naphthalene ring or an anthracene ring, and _{a group represented by −SiR 3} directly bonded to the ring (the R is independently hydrogen). [2] or [3], which is a structural unit containing an atom, a halogen atom, a hydroxy group, an alkyl group, an aryl group, or an alkoxy group; however, at least one of the R is an alkoxy group). The solid-state imaging device according to.

[5] The above-mentioned [1] to [4], wherein the radiation-sensitive compound (B) contains at least one compound selected from a radiation-sensitive acid generator and a radiation-sensitive base generator. Solid-state image sensor.

[6] An electronic device having the solid-state image sensor according to any one of the above [1] to [5].

[7] The electronic device according to the above [6], which is a medical or healthcare camera.

[8] A radiation-sensitive composition containing a resin (A) containing a silicon atom and an aromatic ring and a radiation-sensitive compound (B) for forming a cured film for coating a microlens contained in a solid-state image sensor. thing.

[9] A method for manufacturing a solid-state imaging device having a photoelectric conversion unit that performs photoelectric conversion according to incident light, a microlens that collects the incident light in the photoelectric conversion unit, and a cured film on the microlens. A step of forming a coating film of a radiation-sensitive composition containing a resin (A) containing a silicon atom and an aromatic ring and a radiation-sensitive compound (B) on at least the microlens, and radiation on a part of the coating film. By developing the coating film after irradiation and removing the coating film formed on a portion other than a desired portion, and heating the developed coating film on the microlens. A method for manufacturing a solid-state imaging device, which comprises a step of forming the cured film.

According to the present invention, it is possible to provide a solid-state image sensor having a layer having excellent heat resistance and transparency on a microlens.

FIG. 1 shows an embodiment of the solid-state image sensor of the present invention.

Hereinafter, modes for carrying out the present invention will be described.

[Solid image sensor]
The solid-state image sensor of the present invention
A photoelectric conversion unit that performs photoelectric conversion according to incident light,
A microlens that collects (that is, collects) the incident light on the photoelectric conversion unit,
It has a cured film formed of a radiation-sensitive composition containing a resin (A) containing a silicon atom and an aromatic ring and a radiation-sensitive compound (B) on the microlens.

<Semiconductor substrate>
The solid-state image sensor of the present invention usually has a semiconductor substrate including a photoelectric conversion unit. Here, each pixel of the solid-state image sensor usually has the photoelectric conversion unit. The semiconductor substrate has, for example, an n-type semiconductor region for each pixel with respect to the p-type semiconductor region, that is, a pn junction type photodiode for each pixel. A photodiode is a photoelectric conversion unit that performs photoelectric conversion according to incident light. The incident light is, for example, visible light, infrared light, ultraviolet light, and X-ray.

In one embodiment, the upper surface of the semiconductor substrate, that is, the microlens forming surface is the light incident surface, and the lower surface of the semiconductor substrate is composed of a pixel transistor that reads out the charges accumulated in the photoelectric conversion unit, metal wiring, and an interlayer insulating film. A metal wiring layer is formed.

<Micro lens>
The microlens collects the incident light and causes it to enter the photoelectric conversion unit. The constituent material of the microlens is not particularly limited as long as it has transparency to transmit incident light, but for example, acrylic resin, styrene resin, polyester resin, polyimide resin, polyamide resin, novolak resin, epoxy resin, urethane resin, and melamine resin. , Urea resin, phenol resin, organic resin materials such as these copolymer resins; _{inorganic materials such as SiO 2} (silicon dioxide) and SiN _x (silicon nitride).

The maximum height of the microlens is usually 0.1 to 6 μm, preferably 0.1 to 3 μm. The diameter of the microlens is usually 0.1 to 50 μm, preferably 0.1 to 5 μm. When the diameter of the microlens is small, the influence of the reflected light is usually large, but since the solid-state image sensor of the present invention has the cured film on the microlens, the generation of the reflected light is suppressed.

The refractive index of the microlens at a wavelength of 589 nm is usually 1.4 to 2.5, preferably 1.4 to 2.0.

The solid-state image sensor of the present invention usually has a microlens array composed of a plurality of microlenses. In the microlens array, the position of each microlens corresponds to the position of each pixel. Each corresponding pixel (specifically, each photoelectric conversion unit) receives the incident light collected by each microlens.

<Cured film>
The solid-state image sensor of the present invention has a cured film formed on the microlens.

In the present specification, the expressions such as "member 2 on member 1" and "member 2 formed on member 1" are used when the member 2 is in contact with the member 1 and when the member 2 is not in contact with the member 1. This includes cases where it is located above.

The cured film is formed of a radiation-sensitive composition containing a resin (A) containing a silicon atom and an aromatic ring and a radiation-sensitive compound (B). The cured film functions as an antireflection layer that prevents reflection of incident light on the surface of the microlens. Therefore, in the present invention, the amount of light received by the photoelectric conversion unit can be increased by providing the cured film on the microlens. Details of the radiation-sensitive composition and the conditions for forming the cured film will be described later.

The cured film is preferably a flattening film that hides the unevenness of the microlens, that is, covers the microlens. The cured film is preferably a flattening film formed on the uneven surface of the microlens, particularly a single-layer flattening film. Such a flattening film is excellent in terms of manufacturing cost and suppression of reflected light.

The thickness of the cured film is not particularly limited as long as the microlens is covered with the cured film, but is usually 1 to 10 μm, preferably 1 to 5 μm. The thickness of the cured film refers to the height from the microlens forming surface.

The refractive index of the cured film at a wavelength of 589 nm is usually 1.3 to 2.4, preferably 1.3 to 1.9. The absolute value of the difference in refractive index between the microlens and the cured film laminated on the microlens is usually 0.1 to 1.0, preferably 0.1 to 0 from the viewpoint of suppressing light reflection. It is .5.

<Other parts>
The solid-state image sensor of the present invention may further have a color filter between the photoelectric conversion unit and the microlens. In this case, a microlens is formed on the color filter. The arrangement of each color in the color filter is not particularly limited and is arbitrary. A plurality of color color filters corresponding to each of the photoelectric conversion units can be adopted.

The solid-state image sensor of the present invention can have an antireflection film on the entire upper surface of the semiconductor substrate including the photoelectric conversion unit, which is the light incident surface. The antireflection film has, for example, a two-layer structure of a hafnium oxide film and a silicon oxide film.

In the solid-state image sensor of the present invention, a light-shielding portion may be formed at a boundary portion between pixels on the upper surface of a semiconductor substrate including a photoelectric conversion portion, or, in one embodiment, the upper surface of an antireflection film. The light-shielding portion is formed of, for example, a metal material such as aluminum, tungsten, or copper. By arranging a light-shielding portion between the pixels, it is possible to reduce optical color mixing due to light incident on adjacent pixels. A flattening film that covers the antireflection film and the light-shielding portion may be formed on the upper surface of the antireflection film and the light-shielding portion.

FIG. 1 shows an embodiment of the solid-state image sensor of the present invention. The solid-state image sensor 1 includes a semiconductor substrate 10 including a photoelectric conversion unit 2, an antireflection film 12 formed on the semiconductor substrate 10, a light-shielding portion 14 formed on the antireflection film 12, an antireflection film 12, and an antireflection film 12. A flattening film 16 formed on the light-shielding portion 14 and flattening them, a color filter 18 formed on the flattening film 16, a microlens 20 formed on the color filter 18, and a microlens 20. It has a cured film 30 formed on the surface.

Specifically, the solid-state image sensor of the present invention can be a CMOS image sensor, a CCD image sensor, or the like. The CMOS image sensor may be either a front-illuminated type or a back-illuminated type, but a back-illuminated CMOS image sensor with high sensitivity is preferable. The back-illuminated type has excellent sensitivity characteristics because there is no metal wiring layer on the incident side of the light and the incident light can be efficiently taken into the photoelectric conversion unit.

[Radiation-sensitive composition]
The radiation-sensitive composition of the present invention (hereinafter, also referred to as “composition of the present invention”) contains a resin (A) containing a silicon atom and an aromatic ring, and a radiation-sensitive compound (B). By using the composition of the present invention, a transparent cured film can be formed on the microlens.

<Resin (A)>
The resin (A) contains a silicon atom and an aromatic ring, preferably further containing an acidic group and / or a crosslinkable group.

The resin (A) preferably has an alkoxysilyl group. As the alkoxysilyl group, a group represented _{by −SiR 3 described later is preferable.} Examples of the aromatic ring include a benzene ring, a naphthalene ring, and an anthracene ring, and a benzene ring and a naphthalene ring are preferable, and a benzene ring is more preferable. Examples of the acidic group include the acidic groups described in the << Structural Unit (II) >> column described later. Examples of the crosslinkable group include the crosslinkable group described in the << Structural Unit (III) >> column described later.

The resin (A) has a weight having a structural unit (I) containing an aromatic ring and an alkoxysilyl group directly bonded to the aromatic ring and a structural unit (II) containing an acidic group in the same or different polymer. It is preferably the coalesced component (a). The structural units (I) and (II) may be contained in the same polymer or different polymers, respectively.

<< Structural unit (I) >>
The structural unit (I) includes an aromatic ring and an alkoxysilyl group directly bonded to the aromatic ring. The alkoxysilyl group directly bonded to the aromatic ring means that the silicon atom in the alkoxysilyl group is bonded to the ring carbon atom of the aromatic ring. The structural unit (I) can enhance the heat-resistant transparency of the obtained cured film.

The structural unit (I) may be one type of structural unit or a plurality of types of structural units.

The alkoxysilyl group is preferably a group represented by _{−SiR 3.} The R is independently a hydrogen atom, a halogen atom, a hydroxy group, an alkyl group, an aryl group, or an alkoxy group. However, at least one, preferably at least two, and more preferably all three of the R's are alkoxy groups.

Examples of the aromatic ring to which the alkoxysilyl group is directly bonded include a benzene ring, a naphthalene ring, and an anthracene ring, and a benzene ring and a naphthalene ring are preferable, and a benzene ring is more preferable.

Substituents other than the above-mentioned alkoxysilyl group may be bonded to the aromatic ring. Examples of the substituent include a halogen atom, a hydroxy group, an alkyl group, and an alkoxy group. The substituent may be one type or two or more types, and may be one type or a plurality of types.

Hereinafter, each group in the R and the substituent will be described. The alkyl group preferably has 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 3 carbon atoms. The aryl group preferably has 6 to 20 carbon atoms, more preferably 6 to 10 carbon atoms. The alkoxy group has preferably 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms.

Specific examples of the group represented by −SiR ₃ include a trimethoxysilyl group, a triethoxysilyl group, a tripropoxysilyl group, a dimethoxyhydroxysilyl group, a dimethoxymethylsilyl group, a diethoxyethylsilyl group, and a methoxydimethylsilyl group. Groups are preferred.

Examples of the structural unit (I) include a structural unit represented by the formula (1).

式（１）中、Ｒ^Aは、水素原子、メチル基、ヒドロキシメチル基、シアノ基またはトリフルオロメチル基であり、好ましくは水素原子またはメチル基である。Ｒ¹は、前述した、アルコキシシリル基が直接結合した芳香環であり、Ｘに前記芳香環が結合している。Ｘは、単結合または２価の有機基である。

In the formula (1), ^RA is a hydrogen atom, a methyl group, a hydroxymethyl group, a cyano group or a trifluoromethyl group, and is preferably a hydrogen atom or a methyl group. R ¹ is the above-mentioned aromatic ring in which the alkoxysilyl group is directly bonded, and the aromatic ring is bonded to X. X is a single bond or divalent organic group.

Examples of the divalent organic group include a divalent chain hydrocarbon group having 1 to 20 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a divalent hydrocarbon group having 6 to 20 carbon atoms. A divalent hydrocarbon group such as an aromatic hydrocarbon group; an ester bond (-COO-), a group formed by bonding the divalent hydrocarbon group and an oxy group (-O-), and a combination of these groups. The group can be mentioned.

As X, a single bond and -COO- * (* ^{indicates a bond position with an aromatic ring in R 1} ) are preferable, and a single bond is more preferable.

Examples of the structural unit (I) include structural units represented by the formulas (I-1) to (I-20).

式（Ｉ−１）〜（Ｉ−２０）中、Ｒ^Aは、式（１）中のＲ^Aと同義である。

In formulas (I-1) to (I-20), ^RA is synonymous with ^RA in formula (1).

《Structural unit (II)》
The structural unit (II) has an acidic group. For example, the polymer component (a) can have the structural unit (II) in the same or different polymer as the polymer having the structural unit (I). The structural unit (II) may be one type of structural unit or a plurality of types of structural units. The structural unit (II) can increase the solubility of the polymer component (a) in a developing solution and enhance the curing reactivity.

Examples of the acidic group include a carboxy group, a maleimide group, a sulfo group, a phenolic hydroxyl group, a phosphoric acid group, a phosphonic acid group, a phosphinic acid group, a sulfonamide group, and a hydroxyfluorinated alkyl group.

The structural unit (II) includes, for example, a structural unit derived from an unsaturated carboxylic acid, a structural unit derived from maleimide, a structural unit derived from vinyl sulfonic acid, and 1,1,1,3,3,3-hexafluoro. Examples include structural units derived from -2- (4-vinylphenyl) -propan-2-ol, and structural units derived from hydroxystyrene or α-methylhydroxystyrene.

Examples of the unsaturated carboxylic acid include unsaturated monocarboxylic acids such as (meth) acrylic acid, crotonic acid, and α-chloroacrylic acid; and unsaturated monocarboxylic acids such as maleic acid, itaconic acid, citraconic acid, fumaric acid, and mesaconic acid. Dicarboxylic acids; mono-[(meth) acryloyloxyalkyl] esters of divalent or higher valent carboxylic acids such as mono-succinic acid [2- (meth) acryloyloxyethyl], preferably unsaturated monocarboxylic acids, and more. It is preferably (meth) acrylic acid. From the viewpoint of refractive index, the unsaturated carboxylic acid is preferably not an aromatic unsaturated carboxylic acid.

<< Structural unit (III) >>
The polymer component (a) preferably further has a structural unit (III) containing a crosslinkable group. For example, the polymer component (a) can have the structural unit (III) in the same or different polymer as the polymer having the structural units (I) and / or (II). The structural unit (III) may be one type of structural unit or a plurality of types of structural units. The structural unit (III) can enhance the curing reactivity and the heat-resistant transparency of the obtained cured film.

The crosslinkable group is a group other than the alkoxysilyl group and the acidic group, and refers to a group capable of reacting with each other (for example, epoxy groups) of the same type under heating conditions to form a covalent bond. Examples of the crosslinkable group include an epoxy group such as an oxylanyl group (1,2-epoxy structure) and an oxetanyl group (1,3-epoxy structure), a cyclic carbonate group, a methylol group, a (meth) acryloyl group, and a vinyl group. Can be mentioned.

Examples of the structural unit (III) containing an oxylanyl group include structural units represented by the formulas (III-1) to (III-7) and (III-18). Examples of the structural unit (III) containing an oxetanyl group include structural units represented by the formulas (III-8) to (III-11). Examples of the structural unit (III) containing a cyclic carbonate group include structural units represented by the following formulas (III-12) to (III-16). Examples of the structural unit (III) containing a methylol group include a structural unit represented by the formula (III-17).

式（III−１）〜（III−１８）中、Ｒ^Cは、水素原子、メチル基またはトリフルオロメチル基である。

In formulas (III-1) to (III-18), ^RC is a hydrogen atom, a methyl group or a trifluoromethyl group.

The structural unit (III) containing the (meth) acryloyl group includes, for example, a monomer such as a di (meth) acrylate compound, a tri (meth) acrylate compound, a tetra (meth) acrylate compound, and a penta (meth) acrylate compound. The structural unit from which it is derived can be mentioned.

《Structural unit (IV)》
The polymer component (a) may further have a structural unit (IV) other than the structural units (I) to (III). For example, the polymer component (a) can have the structural unit (IV) in the same or different polymer as the polymer having any one or more of the structural units (I) to (III). The structural unit (IV) may be one type of structural unit or a plurality of types of structural units.

Examples of the monomer giving the structural unit (IV) include (meth) acrylic acid chain alkyl ester, (meth) acrylic acid alicyclic-containing ester, (meth) acrylic acid aryl ester, N-substituted maleimide compound, and unsaturated. Saturated dicarboxylic acid diesters, unsaturated aromatic compounds, halides thereof, as well as bicyclounsaturated compounds, tetrahydrofuran skeletons, furan skeletons, unsaturated compounds with tetrahydropyran skeletons or pyran skeletons, and other unsaturated compounds. It can also be mentioned.

<< Content ratio of each structural unit >>
The lower limit of the content ratio of the structural unit (I) to all the structural units in the polymer component (a) is preferably 10% by mass, more preferably 15% by mass. On the other hand, as the upper limit, 80% by mass is preferable, 60% by mass is more preferable, and 40% by mass is further preferable. In such an embodiment, the composition of the present invention can further improve the heat-resistant transparency of the obtained cured film while exhibiting better radiation-sensitive properties.

The lower limit of the content ratio of the structural unit (II) to all the structural units in the polymer component (a) is preferably 3% by mass, more preferably 5% by mass; and the upper limit is preferably 50% by mass, preferably 40% by mass. % Is more preferable, and 25% by mass is further preferable. In such an aspect, the composition of the present invention is more excellent in coatability and can exhibit better radiation-sensitive characteristics.

When the polymer component (a) has a structural unit (III), the lower limit of the content ratio of the structural unit (III) to all the structural units in the polymer component (a) is preferably 1% by mass, preferably 3% by mass. More preferably; as the upper limit, 75% by mass is preferable, and 65% by mass is more preferable. In such an embodiment, the composition of the present invention can further enhance the heat-resistant transparency of the obtained cured film.

When the polymer component (a) has a structural unit (IV), the lower limit of the content ratio of the structural unit (IV) to all the structural units in the polymer component (a) is preferably 3% by mass, preferably 5% by mass. More preferably; as the upper limit, 50% by mass is preferable, and 40% by mass is more preferable.

The polymer component (a) may be composed of one kind of polymer or two or more kinds of polymers as long as the content of each structural unit measured by NMR analysis satisfies the above requirements. .. In the case of two or more kinds of polymers (blended product), the content ratio (measured value) of each structural unit to the entire blended product may satisfy the above requirements.

Examples of the polymer component (a) include a copolymer having structural units (I) and (II), a mixture of a polymer having structural unit (I) and a polymer having structural unit (II), and a structure. Polymers having units (I), (II) and (III), mixtures of polymers having structural units (I) and (II) and polymers having structural unit (III), structural units (I) ) And a mixture of the polymer having the structural unit (II) and (III), the polymer having the structural unit (I), the polymer having the structural unit (II), and the structural unit (III). Examples include a mixture with a polymer. The polymer or copolymer may further have a structural unit (IV).

The copolymer having structural units (I) and (II) means that the same polymer has structural units (I) and (II). The same applies to other copolymers.

Also, the same type of structural unit is contained in different polymers, such as a mixture of a copolymer having structural units (I) and (II) and a copolymer having structural units (II) and (III). It may be a thing. The copolymer may further have a structural unit (IV).

As the polymer component (a), a copolymer having structural units (I) and (II) is preferable, and a copolymer having structural units (I), (II) and (III) is more preferable, and structural units. Copolymers having (I), (II), (III) and (IV) are more preferred.

The polymer component (a) can be produced, for example, by polymerizing a monomer corresponding to each predetermined structural unit in an appropriate polymerization solvent using a radical polymerization initiator. In general, the compounding ratio of each monomer at the time of polymerization is the same as the content ratio of the corresponding structural unit in the obtained polymer component (a). Further, as the polymer component (a), a plurality of types of polymers may be synthesized, and then the plurality of types of polymers may be mixed and used.

<< Physical characteristics and content ratio of resin (A) >>
The polystyrene-equivalent weight average molecular weight (Mw) of the resin (A) by the gel permeation chromatography (GPC) method is preferably 1,000 to 30,000. The ratio (Mw / Mn) of the Mw of the resin (A) to the polystyrene-equivalent number average molecular weight (Mn) by the GPC method is preferably 1 to 3. Details of the measurement conditions of the GPC method are described in the Examples column.

The lower limit of the content of the resin (A) in the total solid content of the composition of the present invention is preferably 50% by mass, more preferably 70% by mass, still more preferably 90% by mass; the upper limit is 99% by mass. Preferably, 97% by mass is more preferable. The total solid content refers to all components other than the organic solvent (G).

<Radiation-sensitive compound (B)>
Examples of the radiation-sensitive compound (B) (hereinafter, also referred to as “component (B)”) include a radiation-sensitive acid generator which is a compound that generates an acid by a treatment including irradiation, and a base by a treatment including irradiation. Examples thereof include a radiation-sensitive base generator, which is a compound that generates the above-mentioned acid generator. Examples of radiation include ultraviolet rays, far ultraviolet rays, visible rays, X-rays, and electron beams. As the treatment, depending on the type of the component (B), only irradiation may be sufficient, and water contact treatment may be required.

By irradiation treatment or the like on the coating film formed from the composition of the present invention, an acid or a base is generated in the irradiated portion based on the component (B), and based on the action of the acid or the base, the coating film on the alkaline developer is coated. Solubility changes.

As an example, a case where the polymer component (a) having the structural units (I) and (II) and the radiation-sensitive acid generator are used will be described. When the coating film of the radiation-sensitive composition is irradiated with radiation, the structural unit (I) is subjected to a hydrolysis reaction with water in the air or a developing solution using an acid generated from the radiation-sensitive acid generator as a catalyst. It is considered that a silanol group is generated from the alkoxysilyl group in), and the silanol group enhances the solubility of the radiation irradiation region in the alkaline developing solution. Therefore, the radiation-sensitive composition of the above-described embodiment can exhibit highly sensitive positive radiation-sensitive characteristics. Further, it is considered that the condensation reaction of the alkoxysilyl group in the structural unit (I) proceeds by the heat treatment after the development treatment to form a polysiloxane.

Examples of the radiation-sensitive acid generator include an oxime sulfonate compound, an onium salt, a sulfonimide compound, a halogen-containing compound, a diazomethane compound, a sulfone compound, a sulfonic acid ester compound, a carboxylic acid ester compound, and a quinonediazide compound. Examples of the radiation-sensitive base generator include a base generator that generates an amine by irradiation.
Specific examples of the oxime sulfonate compound, onium salt, sulfonimide compound, halogen-containing compound, diazomethane compound, sulfone compound, sulfonic acid ester compound and carboxylic acid ester compound include, for example, paragraph [0078] of JP-A-2014-157252. ~ [0106] and the compounds described in WO 2016/124493 are mentioned, and these acid generators shall be described herein.

The component (B) can be used alone or in combination of two or more.

The content of the component (B) in the composition of the present invention is usually 0.05 to 30 parts by mass, preferably 0.05 to 20 parts by mass, more preferably 100 parts by mass with respect to 100 parts by mass of the resin (A). It is 0.05 to 10 parts by mass.

<Additive (X)>
The composition of the present invention can further contain the additive (X). Examples of the additive (X) include a thermoacid generator, a thermobase generator, an adhesion aid, an acid diffusion control agent, a solubility accelerator, an antioxidant, a surfactant, a crosslinkable compound, and a polymerization initiator. Can be mentioned.

In the composition of the present invention, the upper limit of the total content ratio of the additive (X) in the total solid content may be preferably 20% by mass, more preferably 15% by mass, or 10% by mass. May be even more preferred.

<Organic solvent (G)>
The composition of the present invention can further contain an organic solvent (G). As the organic solvent (G), an organic solvent that uniformly dissolves or disperses each component contained in the composition of the present invention and does not react with each of the above components is used. Examples of the organic solvent (G) include an alcohol solvent, an ester solvent, an ether solvent, an amide solvent, a ketone solvent, and an aromatic hydrocarbon solvent.

The organic solvent (G) can be used alone or in combination of two or more.

The content of the organic solvent (G) in the composition of the present invention is usually 5 to 95% by mass, preferably 10 to 90% by mass, and more preferably 15 to 85% by mass.

<Method for preparing radiation-sensitive composition>
The composition of the present invention is prepared by mixing, for example, the resin (A), the component (B), and the additive (X), if necessary, in a predetermined ratio and dissolving them in an organic solvent (G). The prepared radiation-sensitive composition is preferably filtered through, for example, a filter having a pore size of about 0.2 μm.

[Manufacturing method of solid-state image sensor]
An example of the method for manufacturing the solid-state image sensor of the present invention is described below.

The method for producing a solid-state imaging device of the present invention includes a step of forming a coating film of the above-mentioned radiation-sensitive composition of the present invention on at least a microlens, a step of irradiating a part of the coating film with radiation, and after irradiation. The step of developing the coating film and removing the coating film formed in a portion other than a desired portion, and the step of forming the cured film on the microlens by heating the developed coating film. Have.

For example, in the method for manufacturing a solid-state image sensor of the present invention, a microlens is formed on a semiconductor substrate including a photoelectric conversion unit, and then a cured film is formed on the microlens using the radiation-sensitive composition of the present invention. do.

In the microlens, for example, a radiation-sensitive resin layer made of a conventionally known radiation-sensitive resin composition is formed on a semiconductor substrate including a photoelectric conversion unit, and the radiation-sensitive resin layer is formed in pixel units by a photolithography technique. The resin layer, which has been pattern-processed and patterned in pixel units, can be formed by deforming the resin layer into a lens shape that is convex upward and has a curved surface by melt flow processing. The conventionally known radiation-sensitive resin composition is not particularly limited, and examples thereof include a positive-type radiation-sensitive acrylic resin composition and a positive-type radiation-sensitive styrene resin composition. For example, the radiation-sensitive resin compositions described in JP-A-6-18702, JP-A-6-136239, JP-A-2010-134422, and JP-A-2018-0365666, particularly positive-type radiation-sensitive resins. The composition can be used to form microlenses.

_{In the microlens, an inorganic material such as SiO 2} or SiN _x is formed on a semiconductor substrate including a photoelectric conversion part by a method such as CVD, and the formed inorganic film is processed into a lens shape by a method such as dry etching. It can also be formed by etching.

At least one selected from the above-mentioned antireflection film, light-shielding portion, flattening film, and color filter may be formed on the light incident surface side of the semiconductor substrate, and these may be formed by a conventionally known method. Can be done.

The cured film forms a coating film of the radiation-sensitive composition of the present invention on at least the microlens (hereinafter, also referred to as “step (1)”), and irradiates a part of the coating film with radiation (hereinafter, referred to as “step (1)”). The coating film irradiated with radiation is developed (hereinafter, also referred to as “step (3)”), and the developed coating film is heated (hereinafter, “step (4)”). It can also be formed by (also called).

In the step (1), the radiation-sensitive composition is used to form a coating film for covering the microlens. Specifically, the radiation-sensitive composition in the form of a solution is applied to the surface of the microlens, and preferably prebaking is performed to remove the organic solvent (G) to form a coating film. Examples of the coating method include a spray method, a roll coating method, a rotary coating method (spin coating method), a slit die coating method, a bar coating method, and an inkjet method. The prebaking conditions vary depending on the type of each contained component, the content ratio, and the like, but can be, for example, about 30 seconds to 10 minutes at 60 to 130 ° C.

In the step (2), a part of the coating film is irradiated with radiation. Examples of radiation include ultraviolet rays, far ultraviolet rays, visible rays, X-rays, and electron beams. Examples of ultraviolet rays include g-line (wavelength 436 nm), h-line (wavelength 405 nm), and i-line (wavelength 365 nm). Among these radiations, ultraviolet rays are preferable, and among the ultraviolet rays, radiation containing any one or more of g-rays, h-rays and i-rays is more preferable. The amount of radiation exposure is preferably 0.1 to 10,000 J / m ^2. For higher sensitivity, the coating film may be wetted with a liquid such as water before irradiation.

In the step (3), the coating film irradiated with radiation is developed. Specifically, the coating film irradiated with radiation in step (2) is developed with a developing solution, and in the case of the positive type, the irradiated portion is subjected to radiation, and in the case of the negative type, the radiation is not applied. Remove the irradiated area. By the developing process, it is possible to remove the coating film other than the desired portion, for example, the portion where the microlens is formed. In order to increase the sensitivity, the coating film may be wetted with a liquid such as water before development. After development, it is preferable to rinse the patterned coating film by washing with running water.

The developer is usually an alkaline developer, and examples thereof include an aqueous solution of a basic compound. Examples of the basic compound include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, diethylaminoethanol, di-n-propylamine, and triethylamine. Methyldiethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, 1,8-diazabicyclo [5.4.0] -7-undecene, 1,5-diazabicyclo [4] .3.0] -5-Nonan can be mentioned. The concentration of the basic compound in the aqueous solution is, for example, 0.1 to 10% by mass.

Examples of the developing method include a liquid filling method, a dipping method, a rocking dipping method, and a shower method. The development temperature and development time can be, for example, 20 to 30 ° C. and 30 to 120 seconds, respectively.

In step (4), the developed coating film is heated. As a result, the curing reaction of the coating film can be promoted to form a flat cured film that covers the microlens. Examples of the heating method include a method of heating using a heating device such as an oven or a hot plate. The heating temperature is, for example, 120 to 250 ° C. The heating time varies depending on the type of heating equipment, but is, for example, 5 to 40 minutes when the heat treatment is performed on a hot plate and 10 to 80 minutes when the heat treatment is performed in an oven.

[Example of application to electronic devices]
Examples of the electronic device having the solid-state image sensor of the present invention include an image pickup device such as a video camera, a digital camera, and a mobile phone with a camera function; a copying machine using the solid-state image sensor for the image reading unit; a remote control for a game device and a television; Examples include remote control devices such as automatic doors.

Examples of the imaging device include medical or healthcare cameras such as an endoscopic camera, a capsule-type endoscopic camera, a microscope, and a device that performs angiography by receiving infrared light; around an automobile. Alternatively, an in-vehicle camera that photographs the inside of a vehicle or detects an inter-vehicle distance of a vehicle; a surveillance camera; a camera for person authentication; an industrial camera can be mentioned.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. Unless otherwise stated, "parts" means "parts by mass".

[Weight average molecular weight (Mw) and number average molecular weight (Mn)]
The Mw and Mn of the resin were measured by the gel permeation chromatography (GPC) method under the following conditions. The molecular weight distribution (Mw / Mn) was calculated from the obtained Mw and Mn.

Equipment: GPC-101 (manufactured by Showa Denko)
GPC column: GPC-KF-801, GPC-KF-802, GPC-KF-803 and GPC-KF-804 manufactured by Shimadzu GLC are combined. Mobile phase: tetrahydrofuran Column temperature: 40 ° C.
Flow rate: 1.0 mL / min Sample concentration: 1.0 mass%
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene
[Synthesis of resin]
The monomeric compounds used in the synthesis of the resin are shown below.

<< Monomer giving structural unit (I) >>
-STMS: styryltrimethoxysilane-SDMS: styryldimethoxymethylsilane-STES: styryltriethoxysilane
<< Monomer giving structural unit (II) >>
-MA: Methacrylic acid-HFA-ST: 1,1,1,3,3,3-hexafluoro-2- (4-vinylphenyl) -propan-2-ol-MI: maleimide-α-PHS: α- Methyl-p-hydroxystyrene
<< Monomer giving structural unit (III) >>
・ OXMA: OXE-30 (manufactured by Osaka Organic Chemical Industry Co., Ltd.)
(3-Ethyloxetane-3-yl) Methyl Methacrylate / GMA: Glycidyl Methacrylate / ECHMA: 3,4-Epoxy Cyclohexyl Methyl Methacrylate / EDCPMA: Methacrylic Acid [3,4-Epoxytricyclo (5.2.1.0) ^2,6 ) Decan-9-Il]
<< Monomer giving structural unit (IV) >>
-MMA: Methyl methacrylate-HFIPA: Acrylic acid 1,1,1,3,3,3-hexafluoroisopropyl-ST: Styrene-MPTMS: 3-Methoxyloxypropyltrimethoxysilane-MPTES: 3-Methyloxypropyltri Ethoxysilane NVPI: N-vinylphthalimide
[Synthesis Example 1] (Synthesis of resin (M-1))
A flask equipped with a condenser and a stirrer was charged with 8 parts of 2,2'-azobis (2,4-dimethylvaleronitrile) and 200 parts of diethylene glycol methyl ethyl ether. Then, 30 parts of 1,1,1,3,3,3-hexafluoro-2- (4-vinylphenyl) -propan-2-ol, 5 parts of α-methyl-p-hydroxystyrene, 20 parts. 3,4-Epoxycyclohexylmethylmethacrylate and 45 parts of N-vinylphthalimide were charged, substituted with nitrogen, and the temperature of the solution was raised to 70 ° C. while gently stirring, and this temperature was maintained for 5 hours for polymerization. A polymer solution containing the resin (M-1) was obtained. The solid content concentration of this polymer solution was 34% by mass, the Mw of the resin (M-1) was 10,000, and the molecular weight distribution (Mw / Mn) was 2.1.

[Synthesis Examples 2 to 7] Synthesis of Resins (A-1) to (A-4) and (a-1) to (a-2) Monomer compounds of the type and amount shown in Table 1 were used. Except for the above, the same procedure as in Synthesis Example 1 was carried out to synthesize resins (A-1) to (A-4) and (a-1) to (a-2). The solid content concentration of each of the obtained polymer solutions was equivalent to the value of the resin (M-1). The blanks in Table 1 indicate that the corresponding monomer compound was not blended. The content ratio of each structural unit of the obtained resin was equivalent to the charging ratio of the corresponding monomer compound.

［マイクロレンズ用感放射線性組成物の調製］
樹脂（Ｍ−１）１００部（固形分）を含有する重合体溶液と、酸発生剤としての４，４'−［１−［４−［１−［４−ヒドロキシフェニル］−１−メチルエチル］フェニル］エチリデン］ビスフェノール（１．０モル）と１，２−ナフトキノンジアジド−５−スルホン酸クロリド（２．０モル）との縮合物２２部と、接着助剤としてのγ−グリシドキシプロピルトリメトキシシラン２部と、界面活性剤としてのネオス社「ＦＴＸ−２１８」０．２部とを混合し、さらに固形分濃度が１２質量％となるように溶媒としてのジエチレングリコールメチルエチルエーテルを添加した後、孔径０．２μｍのメンブランフィルタで濾過することにより、マイクロレンズ用感放射線性組成物を調製した。

[Preparation of radiation-sensitive composition for microlenses]
A polymer solution containing 100 parts (solid content) of resin (M-1) and 4,4'-[1- [1- [4-hydroxyphenyl] -1-methylethyl) as an acid generator. ] Phenyl] Ethylden] 22 parts of condensate of bisphenol (1.0 mol) and 1,2-naphthoquinonediazide-5-sulfonic acid chloride (2.0 mol) and γ-glycidoxypropyl as an adhesion aid Two parts of trimethoxysilane and 0.2 part of Neos "FTX-218" as a surfactant were mixed, and diethylene glycol methyl ethyl ether as a solvent was further added so that the solid content concentration became 12% by mass. Then, a radiation-sensitive composition for a microlens was prepared by filtering with a polymer filter having a pore size of 0.2 μm.

[Formation of microlens]
Using a clean track, the radiation-sensitive composition for microlenses was applied onto a glass substrate on which an antireflection film was formed, and then prebaked at 90 ° C. for 90 seconds to form a coating film having a film thickness of 0.5 μm. A mask with a 0.25 μm space and a 1.15 μm dot pattern exposed at ^{2000 J / m 2} using a Nikon “NSR2205i12D” reduction projection exposure machine (NA = 0.63, λ = 365 nm (i line)). The coating film was exposed to the coating film. Next, using an aqueous solution of tetramethylammonium hydroxide (developing solution), the coating film after exposure was developed at 25 ° C. for 1 minute by a liquid filling method. After the development treatment, the coating film was rinsed with water and dried to form a pattern film on the glass substrate. Next, using a hot plate, the pattern film was heated at 150 ° C. for 10 minutes and further heated at 200 ° C. for 10 minutes to melt flow to form a microlens. In this way, a member AA having a microlens on the antireflection film of the glass substrate was obtained.

<Preparation of radiation-sensitive composition for cured film>
The radiation-sensitive compound (B), the additive (X) and the organic solvent (G) are shown below.

<< Radiation-sensitive compound (B) >>
B-1: Trifluoromethanesulfonic acid-1,8-naphthalimide B-2: Irgacure PAG121 (manufactured by BASF) (2- [2- (4-methylphenylsulfonyloxyimino)]-2,3-dihydrothiophene- 3-Ilidene] -2- (2-methylphenyl) acetonitrile)
B-3: 4,4'-[1- [4- [1- [4-hydroxyphenyl] -1-methylethyl] phenyl] ethylidene] bisphenol (1.0 mol) and 1,2-naphthoquinonediazide-5 Condensation with -sulfonic acid chloride (2.0 mol) B-4: 1,1,1-tri (p-hydroxyphenyl) ethane (1.0 mol) and 1,2-naphthoquinonediazide-5-sulfonic acid Condensation with chloride (2.0 mol)
<< Additive (X) >>
X-1: 3-glycidyloxypropyltrimethoxysilane X-2: N- (tert-butoxycarbonyl) -2-phenylimidazole
<< Organic solvent (G) >>
G-1: Propylene glycol monomethyl ether acetate (PGMEA) / N-methylpyrrolidone (NMP) = 10/1 (mass ratio)
G-2: Diethylene glycol methyl ethyl ether (EDM) / N-methylpyrrolidone (NMP) = 10/1 (mass ratio)
G-3: Propylene glycol monomethyl ether (PGME) / N-methylpyrrolidone (NMP) = 10/1 (mass ratio)
<Preparation of radiation-sensitive composition for cured film>
[Example 1]
In a polymer solution containing the resin (A-1), 1 part of the radiation-sensitive compound (B-1), (B-2) with respect to an amount corresponding to 100 parts (solid content) of the resin (A-1). ) 0.5 parts were mixed and diluted with an organic solvent (G-1) so that the final solid content concentration was 30% by mass. Then, it was filtered through a membrane filter having a pore size of 0.2 μm to prepare a radiation-sensitive composition for a cured film.

[Examples 2 to 5, Comparative Examples 1 to 2]
The radiation-sensitive compositions of Examples 2 to 5 and Comparative Examples 1 and 2 were prepared by the same method as in Example 1 except that each component of the type and the blending amount (part by mass) shown in Table 2 was used. bottom. The organic solvent (G) shown in Table 2 is the organic solvent type used for dilution.

［放射線感度］
クリーントラックを用い、６０℃で６０秒間ヘキサメチルジシラザン（ＨＭＤＳ）処理したシリコン基板上に硬化膜用感放射線性組成物を塗布した後、９０℃にて２分間ホットプレート上でプレベークして膜厚３μｍの塗膜を形成した。この塗膜に、幅１０μｍのライン・アンド・スペースパターンを有するパターンマスクを介して、ニコン社の「ＮＳＲ２２０５ｉ１２Ｄ」縮小投影露光機（ＮＡ＝０．６３、λ＝３６５ｎｍ（ｉ線））によって所定量の紫外線を照射した。次いで、テトラメチルアンモニウムヒドロキシド２．３８質量％水溶液よりなる現像液を用い、２５℃で６０秒現像処理を行った後、超純水で１分間流水洗浄を行った。このとき、幅１０μｍのライン・アンド・スペースパターンを形成可能な最小露光量を測定した。この測定値が３０００Ｊ／ｍ²未満の場合に放射線感度が良好であり、３０００Ｊ／ｍ²以上の場合に放射線感度が不良であると評価した。

[Radiation sensitivity]
A radiation-sensitive composition for a cured film is applied onto a silicon substrate treated with hexamethyldisilazane (HMDS) at 60 ° C. for 60 seconds using a clean track, and then prebaked on a hot plate at 90 ° C. for 2 minutes to form a film. A coating film having a thickness of 3 μm was formed. A predetermined amount of this coating film is applied to this coating film by a Nikon "NSR2205i12D" reduction projection exposure machine (NA = 0.63, λ = 365 nm (i-line)) via a pattern mask having a line-and-space pattern with a width of 10 μm. Was irradiated with ultraviolet rays. Next, a developing solution consisting of a 2.38% by mass aqueous solution of tetramethylammonium hydroxide was used for development treatment at 25 ° C. for 60 seconds, and then washed with ultrapure water for 1 minute under running water. At this time, the minimum exposure amount capable of forming a line-and-space pattern having a width of 10 μm was measured. This measurement is a good radiation sensitivity of less than 3000 J / m ^2, the radiation sensitivity in the case of 3000 J / m ² or more was evaluated to be defective.

[Applicability]
Using a clean track, the radiation-sensitive composition for a cured film is applied onto the microlens of the member AA produced in the above [formation of microlens], and then prebaked at 90 ° C. for 2 minutes to glass in the member AA. A coating film having a film thickness of 3 μm as the height from the substrate surface was formed. The formed coating film was visually observed, and the coatability was judged according to the following evaluation criteria.

Good: The obtained coating film is even and uniform.

Defective: Pinhole (dot-like unevenness), cissing unevenness, vertical streak unevenness (one or more straight line unevenness formed in the coating direction or in the direction intersecting it), and cloud-like unevenness (cloud-like) in the obtained coating film. There is unevenness such as unevenness).

[Reflectance]
Using a clean track, the radiation-sensitive composition for a cured film is applied onto the microlens of the member AA produced in the above [formation of microlens], and then prebaked at 90 ° C. for 2 minutes to glass in the member AA. A coating film having a film thickness of 3 μm as the height from the substrate surface was formed. The coating film was exposed through a mask having a desired pattern using a Nikon "NSR2205i12D" reduced projection exposure machine (NA = 0.63, λ = 365 nm (i-line)). Next, a developing solution consisting of a 2.38% by mass aqueous solution of tetramethylammonium hydroxide was used for development treatment at 25 ° C. for 60 seconds, and then washed with ultrapure water for 1 minute under running water. Then, it was heated at 200 ° C. for 30 minutes to prepare a measuring member BB. Using the member AA of the above [Formation of microlens] as a reference, a spectral reflectance measuring device (self-recording spectrophotometer U-3410 incorporating a large sample room integrating sphere attachment device 150-09090, manufactured by Hitachi, Ltd.) It was evaluated as good when the reflectance of the measuring member BB at 400 nm was suppressed by 5% or more, and poor when the reflectance was suppressed by less than 5%.

[Heat-resistant transparency]
The substrate prepared under the above [Radiation Sensitivity] was heated at 230 ° C. for 30 minutes to prepare a substrate for measurement, and an ultraviolet-visible light transmission spectrum was collected. Then, the measurement substrate was heated at 250 ° C. for 60 minutes, and then the ultraviolet-visible light transmission spectrum was collected again. At this time, when the decrease in transmittance at a wavelength of 400 nm before and after heating at 250 ° C. was less than 5%, the heat-resistant transparency was evaluated as good, and when it was 5% or more, it was evaluated as poor.

1 ... Solid-state image sensor, 2 ... Photoelectric conversion unit, 10 ... Semiconductor substrate, 12 ... Antireflection film, 14 ... Light-shielding part, 16 ... Flattening film, 18 ... Color filter, 20 ... Microlens, 30 ... Hardened film

Claims (9)

A photoelectric conversion unit that performs photoelectric conversion according to incident light,
A microlens that collects the incident light in the photoelectric conversion unit,
A solid-state image sensor having a cured film formed of a radiation-sensitive composition containing a resin (A) containing a silicon atom and an aromatic ring and a radiation-sensitive compound (B) on the microlens. A structure in which a resin (A) containing a silicon atom and an aromatic ring contains a structural unit (I) containing an aromatic ring and an alkoxysilyl group directly bonded to the aromatic ring in the same or different polymer, and an acidic group. The solid-state imaging device according to claim 1, which is a polymer component (a) having a unit (II). The polymer component (a) contains a crosslinkable group in the same or different polymer as the polymer having at least one structural unit selected from the structural unit (I) and the structural unit (II). The solid-state imaging device according to claim 2, further comprising a structural unit (III). The structural unit (I) is a substituted or unsubstituted benzene ring, naphthalene ring or ankoxy ring and _{a group represented by −SiR 3} directly bonded to the ring (the R is independently a hydrogen atom and a halogen, respectively). The solid-state imaging device according to claim 2 or 3, which is a structural unit containing an atom, a hydroxy group, an alkyl group, an aryl group, or an alkoxy group; however, at least one of the R is an alkoxy group). .. The solid-state image sensor according to any one of claims 1 to 4, wherein the radiation-sensitive compound (B) contains at least one compound selected from a radiation-sensitive acid generator and a radiation-sensitive base generator. An electronic device having the solid-state image sensor according to any one of claims 1 to 5. The electronic device according to claim 6, which is a medical or healthcare camera. To form a cured film that covers the microlens contained in the solid-state image sensor,
Resin (A) containing a silicon atom and an aromatic ring,
A radiation-sensitive composition containing a radiation-sensitive compound (B). A method for manufacturing a solid-state image sensor having a photoelectric conversion unit that performs photoelectric conversion according to incident light, a microlens that collects the incident light in the photoelectric conversion unit, and a cured film on the microlens.
A step of forming a coating film of a radiation-sensitive composition containing a resin (A) containing a silicon atom and an aromatic ring and a radiation-sensitive compound (B) on at least the microlens, and radiation on a part of the coating film. By developing the coating film after irradiation, removing the coating film formed in a portion other than a desired portion, and heating the developed coating film on the microlens. A method for manufacturing a solid-state imaging device, which comprises a step of forming the cured film.

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