JP2002261261A - Imaging device and manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device which has a simple structure, microlenses made of organic resin and having antireflection effect, and marked effects for avoiding flare, ghost, and noise, and to provide its manufacturing method. SOLUTION: Photoelectric transducers 21, light-shielding parts 31, a leveling layer 41, color filters 51, leveling layer 42, and an undercoat layer 61 are formed on a semiconductor substrate 11. Further, microlenses 90 comprising resin lenses 71a and porous layers 81 are formed on resin surface with optical voids (gaps). The voids (gaps) and thicknesses of the porous layers 81 are approximately λ/4 of the wavelength of a light. Light-absorbing layer are formed in recessed parts between the microlenses. Moreover, the etching rate for dry-etching of the undercoat layer 61 is set higher than that of a resin material, of which the resin lenses 71a are made.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to C-MOS and CC
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image sensor represented by a light receiving element such as D, and a micro lens formed on the image sensor, and more particularly, to an image sensor having improved sensitivity and reduced smear by increasing the effective aperture ratio of the micro lens, and a method of manufacturing the same. About.

[0002]

2. Description of the Related Art The area (opening) contributing to photoelectric conversion of a light receiving element such as a CCD depends on the element size and the number of pixels, but is limited to about 20 to 40% of the entire area. Since a small aperture directly lowers the sensitivity, a microlens for condensing light is generally formed on the light receiving element to compensate for this. However, in recent years, there has been a strong demand for high-definition CCD image sensors having more than 2 million pixels. It is becoming. Furthermore, light re-reflected or scattered from the surface of the imaging device (such as the surface of a microlens) and the inner surface of the cover glass is a cause of noise to the imaging device, which is a problem.

As a technique for preventing such noise, a technique for forming an antireflection film on the surface of a microlens has been proposed. For example, a technique of laminating a thin film having a refractive index difference from a lens material on a resin lens is disclosed in Japanese Patent Laid-Open No. Hei 4-223371.
No. 6,086,045. Here, although the names of the materials used are not disclosed, they are shown as two-layer antireflection films having a high refractive index and a low refractive index formed on the microlens surface.

Further, as a means for forming a convex lens-shaped microlens, a technique called a heat flow method is disclosed. Japanese Patent Application Laid-Open No. 6-1124 discloses a stable production technique or a high aperture ratio technique for avoiding sticking between adjacent microlenses which occurs when the heat flow method is used.
No. 59, Japanese Patent Application Laid-Open No. 9-45884 and the like disclose a technique called “groove method” using etching. It is necessary to provide a narrow gap between the microlenses formed on the high-definition CCD. However, although these techniques can form a concave portion for preventing sticking between lenses, they are hardly a narrowing means for reducing the concave portion. That is, since the concave portion is formed by etching using a microlens as a master mold by dry etching or the like, the concave portion is basically processed at the same time as the lens shape tends to be gently widened. In both cases of isotropic etching and anisotropic etching, the gap is not basically processed into a narrower gap than the master pattern. The “groove method” is effective in a wide gap of 1 μm level as disclosed in Japanese Patent Application Laid-Open No. 6-112459, and cannot reproduce a narrow gap of 0.3 μm or less. The disclosed technology is a technology for basically processing a shape between lenses smoothly.

[0005]

In order to reduce re-reflected light and scattered light between the inner surface of the cover glass and the surface of the microlens, an effective method is to use a low-refractive-index fluoride (or a low-refractive-index oxidized material). It is effective to form an inorganic multi-layered film obtained by laminating a high-refractive-index oxide on a microlens surface as an antireflection film. Such oxides and fluorides can provide a large difference in refractive index, so that a high-performance antireflection film can be manufactured. However, this kind of antireflection film needs to be formed using a vacuum device such as a vapor deposition machine, and is an extremely costly method.

Moreover, when a vapor deposition machine or the like is used, it is inevitable that foreign matter adheres due to the peeling of the vapor deposition material adhered to the inside of the vacuum chamber, and it can be said that the semiconductor device forming process has a large reduction in yield. In addition, forming an inorganic multilayer film on the surface of a microlens made of an organic resin is inferior in reliability due to a difference in coefficient of thermal expansion and a difference in the degree of water content. Further, in the conventional configuration, it is difficult to avoid that light entering the concave portion between the microlenses from an oblique direction enters the photoelectric conversion element, causing flare, ghost, and noise, which leads to deterioration of image quality.

[0007] Higher definition of the image sensor has required an arrangement of microlenses with a pitch of 5 µm or less and a gap between lens patterns of 0.3 µm or less (hereinafter abbreviated as a narrow gap). However, in general, microlenses are formed by using a photolithography method using a photosensitive resin and a heat flow technique in combination. Due to the restrictions brought by these techniques, a gap dimension (inter-lens dimension) of the microlens in a side direction. Is from 1 μm to at most 0.4 μm. If the inter-lens size is 0.3 μm or less, adjacent microlenses are often stuck at each pattern edge, resulting in non-uniformity, which is not a mass production level technology. Such a restriction caused by the conventional technique has a problem that the aperture ratio of the microlens is reduced due to the high definition, in other words, the sensitivity of the imaging device is reduced.

A technique for isotropically depositing an inorganic film or a resin film on a resin lens to achieve a narrow gap is as follows.
For example, as disclosed in a method of synthesizing and depositing a urea resin using an evaporator, and as disclosed in JP-A-5-48057,
There is a method of depositing using CVD such as ECR plasma. However, these techniques require expensive vacuum equipment and CVD.
This method requires the use of an apparatus, and is not a simple method, but a significant cost increase.

The present invention has been devised in view of the above problems, and has a microlens having a simple structure and an organic resin structure having an antireflection effect, and has a remarkable effect on preventing flare, ghost and noise. It is an object of the present invention to provide an imaging device and a method for manufacturing the same.

[0010]

In order to achieve the above object, the present invention first provides at least a plurality of photoelectric conversion elements, a flattening layer, a color filter, and an undercoat layer. And a microlens, wherein the microlens comprises a resin lens and a porous layer having an optical void (gap) on the resin surface.

According to a second aspect of the present invention, in the imaging device according to the first aspect, a void (gap) and a thickness of the porous layer are approximately λ / 4 of a light wavelength in a visible light region. It is what it was.

According to a third aspect of the present invention, there is provided the image pickup device according to the first or second aspect, wherein a concave portion is formed between the microlenses, and a light absorbing layer is provided in the concave portion. Things.

According to a fourth aspect of the present invention, the material of the undercoat layer is made of a resin having an etching rate higher than that of the resin constituting the resin lens. The image pickup device described in the section.

According to a fifth aspect of the present invention, there is provided a method of manufacturing an image sensor, comprising at least the following steps. (A) a photoelectric conversion element, a light shielding portion, a flattening layer,
A step of manufacturing an image pickup device in an intermediate step in which a color filter, a flattening layer, and an undercoat layer are formed. (B) applying a photosensitive material on the undercoat layer,
A step of forming a photosensitive resin layer, and exposing and developing to form a resin pattern. (C) forming a resin lens by heat-flowing the resin pattern. (D) a step of forming a concave portion in the exposed undercoat layer between the resin lenses (e) applying a transparent resin on the resin lens to form a transparent resin layer, and dry-etching the transparent resin layer Thereby, a porous layer is formed such that the voids (voids) and the thickness of the resin surface are approximately λ / 4 of the wavelength of light.
A step of producing an image sensor;

Still further, according to a sixth aspect of the present invention, there is provided a method of manufacturing an imaging device, comprising at least the following steps. (A) a photoelectric conversion element, a light shielding portion, a flattening layer,
A step of manufacturing an image pickup device in an intermediate step in which a color filter, a flattening layer, and an undercoat layer are formed. (B) applying a photosensitive material on the undercoat layer,
A step of forming a photosensitive resin layer, and exposing and developing to form a resin pattern. (C) forming a resin lens by heat-flowing the resin pattern. (D) forming a concave portion in the exposed undercoat layer between the resin lenses; and (e) applying a black resin containing a light absorbing agent to the resin lens and the concave portion between the resin lenses to form a black resin layer. Removing the black resin layer on the resin lens, and forming a light absorbing layer in a concave portion between the resin lenses. (F) A transparent resin is applied on the resin lens to form a transparent resin layer, and the transparent resin layer is dry-etched, so that the voids (voids) and the thickness of the resin surface are approximately λ of the wavelength of light. A step of forming a porous layer having a thickness of / 4 and manufacturing an image sensor.

The terms related to microlenses used in the present invention will be described. The micro lens 140 is shown in FIG.
As shown in (a) to (c), a resin lens 121 and a transparent resin layer 131 formed on the resin lens 121 are provided.
Means a resin lens before is formed. The dimension between the lenses indicates a dimension between pattern edges in the side direction of the resin lens 121. The gap size is determined based on the position of an inflection point extending from the curved surface of the transparent resin layer 131 constituting the microlens 140 to the concave portion 141, and the narrower dimension between the inflection points (the larger one is the lens opening dimension). Point. Since the gap size (concave size) in the present invention is equal to or less than the wavelength of light, it has no optically concave lens effect. The “depth of the concave portion” used in the present invention roughly indicates the depth from the inflection point of the curved surface of the lens cross section to the bottom of the concave portion 141. The concave portion 141 indicates a concave portion between the micro lenses 140.

[0017]

Embodiments of the present invention will be described below. FIG. 1A is a partial schematic plan view showing an embodiment of the imaging device of the present invention, and FIG. 1B is a partial schematic plan view of FIG. 1A cut along line AA ′. FIGS. 2A to 2E are partial schematic structural cross-sectional views of an image sensor, showing an embodiment of a method of manufacturing an image sensor according to claim 5 of the present invention in the order of steps. FIG.
(A) to (f) are partial schematic structural cross-sectional views of an image sensor showing an embodiment of a method for manufacturing an image sensor according to the sixth aspect of the present invention in the order of steps, and FIG. The schematic configuration sectional views of the porous layer are shown respectively.

The image pickup device according to the first aspect of the present invention is directed to a semiconductor substrate 11 as shown in FIGS. 1 (a) and 1 (b).
The photoelectric conversion element 21, the light shielding portion 31, the flattening layer 41, the color filter 51, the flattening layer 42, and the undercoat layer 6
An image pickup device in an intermediate step where 1 is formed is manufactured. further,
This is to produce an imaging device in which a micro lens 90 formed of a resin lens 71a and a porous layer 81 having an optical void (gap) formed on the resin surface. According to a second aspect of the image pickup device of the present invention, in the porous layer 81 having optical voids (voids) formed on the resin lens, the pitch and thickness of the voids (voids) are adjusted to the light wavelength in the visible light region. Of the porous layer 8
By lowering the apparent refractive index in No. 1, the resin lens has an antireflection effect. According to a third aspect of the present invention, a light absorbing layer is formed in a concave portion between microlenses to absorb light incident between microlenses and to prevent a reduction in the S / N ratio of an image sensor due to stray light. is there. In the invention according to claim 4 of the imaging device of the present invention, the etching rate of the undercoat layer 61 at the time of etching by dry etching or the like is set to a higher value than the resin material constituting the resin lens 71a. This is because the surface shape of the resin lens is maintained when the concave portion 62 is formed between the resin lenses 71a by dry etching or the like after the resin lens 71a is formed on the undercoat layer described later.

A method for manufacturing an image pickup device according to claim 5 of the present invention will be described. First, an image pickup device in an intermediate step in which a photoelectric conversion element 21, a light shielding portion 31, a flattening layer 41, a color filter 51, a flattening layer 42, and an undercoat layer 61 are formed on a semiconductor substrate 11 is manufactured (FIG. 2A). reference).
Next, a photosensitive resin solution is applied on the undercoat layer 61 by a spin coater or the like to form a photosensitive resin layer, and is exposed and developed to form a resin pattern 71 (FIG. 2).
(B)). 2 (b) to 2 (d), the portions from the semiconductor substrate 11 to the planarization layer 42 are not shown. The thickness of the photosensitive resin layer is as thin as 0.3 μm or less, so that the resin lens shape after the formation of the resin pattern 71 is easily maintained, and a narrow gap between the lenses is easily achieved. Further, in order to improve coatability and dispersibility, a surfactant may be added to the photosensitive resin solution, a plurality of solvent types may be mixed, or the molecular weight of the resin or other resins may be added. In addition, as a pre-treatment for application, the undercoat layer may be lightly etched, plasma-treated, ultraviolet-washed, or the like.

Next, the resin pattern 71 is heat-flowed to form a resin lens 71a (see FIG. 2C).
The resin material used for forming the resin lens 71a includes a transparent resin for forming a porous layer, which will be described later, and a material for forming an undercoat layer.
It is only required that they have high reliability and practical reliability (heat resistance, light resistance, heat resistance cycle, etc.). For example, acrylic resin, epoxy resin, polyester resin, urethane resin, melamine resin, urea resin such as area resin, phenolic resin or a copolymer thereof can be used as a material of the resin lens, and generally, phenol-based A photosensitive resin or a low molecular weight melamine-epoxy copolymer is used.

Next, the undercoat layer 61 exposed between the resin lenses 71a is subjected to plasma ashing and dry etching to form a concave portion 62 (see FIG. 2D). Here, the undercoat layer 61 and the resin lens 71
a, the etching rate is different from that of the resin lens 7.
Since the etching rate of the undercoat layer 61 is set higher than 1a, the concave portion 62 can be formed while the surface shape of the resin lens 71a is maintained.
The depth of the concave portion 62 may be set in the range of 6 μm to 0.05 μm. However, if the depth of the concave portion 62 exceeds 1.5 μm, application unevenness occurs when a transparent resin layer is formed on the resin lens 71 a. Preferably, it is in the range of 1.5 to 0.05 μm. .

Next, the resin lens 7 having the concave portion 62 is formed.
1a is coated with a transparent resin solution by spin coating or the like,
A transparent resin layer is formed. As the transparent resin solution, a solution obtained by mixing an appropriate amount of a curing agent into an epoxy resin or an acrylic resin is used. Further, by dry-etching the resin surface of the transparent resin layer in an oxygen plasma atmosphere, a porous layer 81 having optical voids (voids) 81b in which columnar resins 81a are arranged on the resin lens 71a is formed. An image sensor 100 is obtained (see FIGS. 2E and 4).
The pitch or size of the columnar resin 81a is 0.03.
It is desirable to set it to 0.3 μm.

FIG. 4 is a schematic sectional view of the structure of the porous layer 81. As shown in FIG. 4, the porous layer 81 has a columnar resin 81a and voids (voids) 81b formed on a resin lens 71a. In a general resin film, a large number of fine bubbles exist in the film, and when the density decreases, the refractive index of the resin film decreases. In the porous layer 81, the voids (voids) 81b have the role of the air bubbles, and the refractive index is lowered to function as a reflective film. In other words, by using a porous layer, it is possible to form an antireflection film using a low-priced resin without using an expensive resin even if the refractive index is low, such as a fluorine-based resin.

The void (gap) 81b can be expressed by a pitch V _P between the columnar resin 81a, becomes V _P = 0.1 to 0.2 [mu] m to be approximately lambda / 4 optical wavelengths in the visible light region ing. The thickness Vt of the porous layer 81 is also set to be λ / 4 (0.1 to 0.2 μm) of the light wavelength in the visible light region. With such a configuration, the light reflected from the porous layer 81 after being incident on the porous layer 81 has a phase shift, and the incident light and the reflected light cancel each other out, and the porous layer 81 has an antireflection effect. Will have. Further, if the difference in the refractive index between the porous layer 81 and the resin lens 71a is reduced,
The reflection at the interface with a can be prevented. In this way, by suppressing the reflection of light on the surface of the microlens, noise light that causes re-reflection from the cover glass of the image sensor and causes smear due to re-incident light is reduced, and the characteristics of the image sensor are deteriorated. Preventing.

A method for manufacturing an image pickup device according to claim 6 of the present invention will be described. First, an image pickup device in an intermediate step in which a photoelectric conversion element 21, a light shielding portion 31, a flattening layer 41, a color filter 51, a flattening layer 42, and an undercoat layer 61 are formed on a semiconductor substrate 11 is manufactured (FIG. 3A). reference).
Next, a photosensitive resin solution is applied on the undercoat layer 61 by a spin coater or the like to form a photosensitive resin layer, and exposed and developed to form a resin pattern 71 (FIG. 3).
(B)). 3B to 3E, the portions from the semiconductor substrate 11 to the planarization layer 42 are not shown. If the thickness of the photosensitive resin layer is as thin as 0.3 μm or less, it is easy to maintain the shape of the resin lens after the resin pattern 71 is formed, and it is easy to achieve a narrow gap between the lenses. Further, in order to improve coatability and dispersibility, a surfactant may be added to the photosensitive resin solution, a plurality of solvent types may be mixed, or the molecular weight of the resin or other resins may be added. In addition, as a pre-treatment for application, the undercoat layer may be lightly etched, plasma-treated, ultraviolet-washed, or the like.

Next, the resin pattern 71 is heat-flowed to form a resin lens 71a (see FIG. 3C).
The resin material used to form the resin lens 71a, including the transparent resin forming the porous layer and the material forming the undercoat layer, has high transparency in the visible region (visible region transmittance), and has practical reliability (heat resistance). , Light resistance, heat resistance cycle, etc.). For example, acrylic resin, epoxy resin, polyester resin, urethane resin, melamine resin, urea resin such as area resin, phenolic resin, or a copolymer thereof can be used as a resin lens material. A hydrophilic resin or a low molecular weight melamine-epoxy copolymer is used.

Next, the exposed undercoat layer 61 between the resin lenses 71a is subjected to plasma ashing, dry etching or the like to form a concave portion 62 (see FIG. 3D). Here, the undercoat layer 61 and the resin lens 71
a, the etching rate is different from that of the resin lens 7.
Since the etching rate of the undercoat layer 61 is set higher than 1a, the concave portion 62 can be formed while the surface shape of the resin lens 71a is maintained.
The depth of the concave portion 62 may be set in the range of 6 μm to 0.05 μm. However, if the depth of the concave portion 62 exceeds 1.5 μm, application unevenness occurs during the formation of the transparent resin layer. ０．０５0.05 μm.

Next, a colored resin solution containing a light absorbing agent such as carbon or a coloring agent is applied by a spin coater, dried and heat reflowed to form a light absorbing resin layer. The resin layer is removed by plasma ashing or the like, and a light absorbing layer 63 is formed in the recess 62.
(E)). The light absorbing layer 63 absorbs light incident between the microlenses, and prevents a decrease in the S / N ratio of the image sensor due to stray light.

Next, a transparent resin solution is applied on the resin lens 71a by spin coating or the like to form a transparent resin layer. As the transparent resin solution, a solution obtained by mixing an appropriate amount of a curing agent into an epoxy resin or an acrylic resin is used. Further, the resin surface of the transparent resin layer is dry-etched in an oxygen plasma atmosphere to form a columnar resin 8 having a pitch or size of 0.03 to 0.3 μm on the resin lens 71a.
A porous layer 81 having an optical void (gap) 81b in which 1a is arranged is formed, and an image sensor 200 of the present invention is obtained (see FIGS. 3F and 4). By providing a light absorbing layer and a porous layer, the reflection of light from the microlens surface or the concave portion between the microlenses is suppressed, so that the reflection from these ineffective portions is re-reflected from the cover glass of the image sensor and re-incident. As a result, noise light that causes smear or the like is reduced to prevent the characteristics of the image sensor from deteriorating, and to prevent a reduction in the S / N ratio of the image sensor due to stray light.

[0030]

The present invention will be described in detail with reference to the following examples. <Example 1> First, a light-shielding portion 31 was formed on a semiconductor substrate 11 on which a photoelectric conversion element 21 was formed by a known technique and method.
Flattening film 41, color filter 51 and flattening film 42
Were sequentially formed, and an undercoat layer 61 was formed by spin-coating an epoxy-based resin solution on the flattening layer 42 to manufacture an image sensor in an intermediate step (see FIG. 2A).

Next, a phenol-based photosensitive resin solution (trade name "380H": manufactured by JSR Corporation) is applied on the undercoat layer 61 of the image pickup device in the intermediate step by a spinner and dried to a thickness of 1.2 μm. Form a photosensitive resin layer, using a photomask having a predetermined pattern the photosensitive resin layer,
A series of patterning processes such as exposure and development are performed to form a resin pattern 7 having a pitch of 5 μm and a gap of 0.6 μm corresponding to the arrangement of the photoelectric conversion elements 31 on the undercoat layer 61.
1 was formed (see FIG. 2B).

Next, the image pickup device in the intermediate step in which the resin pattern 71 is formed is heated at 180 ° C. for 3 minutes on a hot plate and subjected to a heat flow treatment, so that a gap in the side direction on the undercoat layer 61 is 0.4 μm. 1.4 μm lens height
The resin lens 71a was formed (see FIG. 2C).

Next, using a dry etching apparatus, O
₂ gas introduced, pressure: 20Pa, RF power: 1k
w, substrate temperature: room temperature (RT), processing time: 25 seconds,
Etching was performed to form a concave portion 62 having a depth of 0.3 μm in the undercoat layer 61 between the resin lenses 71a (see FIG. 2D). Here, under the above-mentioned etching conditions, the etching rate of the photosensitive phenol-based resin used for forming the resin lens 71a is equal to that of the undercoat layer 61.
Of the etching rate of the epoxy resin used to form
/ 3. Since the etching rate of the photosensitive phenolic resin, which is the material of the resin lens, is small, the
Even after the concave portion 62 of μm is formed, the lens shape of the resin lens is maintained, and the effect of reducing the change in the curvature of the lens and the concave portion in the diagonal direction between the microlenses can be deeply processed. The narrow gap of the resin lens can be realized.

Next, a transparent acrylic resin (trade name “TO”)
C ": Fuji Pharmaceutical Co., Ltd.) 5 parts of an acid-based curing agent (trade name" TOHC-HA ") mixed with 2 parts of an acrylic resin solution is applied by spin coating to form a resin lens 71a and a concave portion 62. A transparent resin layer having a thickness of less than 0.2 μm was formed so as to cover. As a result, the gap dimension between the microlenses (resin lens and transparent resin layer) was as narrow as 0.1 μm. Further, 50 sc of oxygen is supplied to the dry etching apparatus.
cm, pressure: 20 Pa, RF power: 1 kw,
The surface of the transparent resin layer was etched at a substrate temperature of room temperature (RT) and a processing time of 20 seconds to form a porous layer 81. In the porous layer 81, columnar resins 81a of about 0.1 μm were arranged at a pitch of 0.05 to 0.15 μm. Through the steps described above, the image sensor 100 having the microlenses 90 in which the porous layer 81 was formed on the resin lens 71a was obtained (see FIG. 2E).

The reflectivity of the microlens 90 in which the porous layer 81 is formed on the resin lens 71a of the imaging device 100 obtained in the first embodiment is 1/4 of that in the case where the porous layer 81 is not formed. It showed low reflectance. FIG. 5 shows an electron micrograph (magnification: 60,000) showing the texture of the surface of the porous layer 81 obtained in Example 1. About 0.1
It was confirmed that a resin column of μm was formed.

<Embodiment 2> First, a light shielding portion 31, a flattening film 41, and a color filter 51 are formed on a semiconductor substrate 11 on which a photoelectric conversion element 21 is formed by a known technique and method.
Then, a flattening film 42 is sequentially formed, and an epoxy resin solution is spin-coated on the flattening layer 42 to form an undercoat layer 61, thereby producing an image sensor in an intermediate step (FIG. 3).
(A)).

Next, a phenol-based photosensitive resin solution (trade name "380H": manufactured by JSR Corporation) is applied on the undercoat layer 61 of the image pickup device in the intermediate step by a spinner, and dried to a thickness of 1.2 μm. Form a photosensitive resin layer, using a photomask having a predetermined pattern the photosensitive resin layer,
A series of patterning processes such as exposure and development are performed to form a resin pattern 7 having a pitch of 5 μm and a gap of 0.6 μm corresponding to the arrangement of the photoelectric conversion elements 31 on the undercoat layer 61.
1 was formed (see FIG. 3B).

Next, the image sensor in the intermediate step where the resin pattern 71 is formed is heated on a hot plate at 180 ° C. for 3 minutes and subjected to a heat flow treatment, so that a gap in the side direction on the undercoat layer 61 is 0.4 μm. 1.5μm lens height
The resin lens 71a was formed (see FIG. 3C).

Next, using a dry etching apparatus,
₂ gas introduced, pressure: 20Pa, RF power: 1k
w, substrate temperature: room temperature (RT), processing time: 25 seconds,
Etching was performed to form a concave portion 62 having a depth of 0.4 μm in the undercoat layer 61 between the resin lenses 71a (see FIG. 3D).

Next, a light absorbing resin solution containing 8% of carbon having a particle size of 0.1 μm or less in a thermosetting phenol resin at a solid ratio of 8% is applied by a spinner so as to cover the resin lens 71a and the concave portion 62. Then, the temperature is raised at a stretch to 200 ° C. on a hot plate at 200 ° C., the resin is cured, a light absorbing resin layer is formed, and the thin film light absorbing resin layer on the resin lens 71 a is removed by plasma treatment. Then, a light absorbing layer 63 was formed in the concave portion 62 (see FIG. 3E). Since the light absorbing resin has a heat flow property, the resin melts when the temperature rises, flows into the concave portion 62, and the light absorbing layer 63 having a thickness of about 0.7 μm is formed. .1μ
The thin film light absorbing resin layer of m remained and was removed by plasma treatment.

Next, a transparent acrylic resin (trade name "TO")
C ": Fuji Chemical Co., Ltd.) 5 parts of an acid-based curing agent (trade name" TOHC-HA ") mixed with 2 parts of an acrylic resin solution is applied by spin coating to cover the resin lens 71a. A transparent resin layer having a thickness of less than 0.2 μm was formed. Further, oxygen was introduced into the dry etching apparatus at 50 sccm, pressure: 20 Pa, RF power: 1 kw, substrate temperature:
The surface of the transparent resin layer was etched at room temperature (RT) at a processing time of 20 seconds to form a porous layer 81. The porous layer 81 has a columnar resin 81a of about 0.1 μm.
Were arranged at a pitch of 0.05 to 0.15 μm.
Through the above steps, the porous layer 8 is formed on the resin lens 71a.
An image sensor 200 having the light absorbing layer 63 between the microlenses 90 on which the light-emitting elements 1 were formed was obtained (FIG. 3F).
reference).

The reflectivity of the microlens 90 in which the porous layer 81 is formed on the resin lens 71a of the image pickup device 200 obtained in the second embodiment is 1/4 of that in the case where the porous layer 81 is not formed. It showed low reflectance. FIG. 5 shows an electron micrograph (magnification: 60,000) showing the texture of the surface of the porous layer 81 obtained in Example 2. About 0.1
It was confirmed that a resin column of μm was formed.

[0043]

According to the present invention, since a microlens having a porous layer formed on a resin lens is provided on an image sensor element, reflection and scattering of light on the microlens are suppressed, and a substantial aperture is provided. An image sensor capable of improving the rate and achieving a significant improvement in the S / N ratio can be provided at low cost. Further, since the light absorbing layer is formed selectively (self-aligned) between the microlenses, the light absorbing layer can be formed with high alignment accuracy, oblique incident light and scattered light can be cut, and the S / S of the image sensor can be reduced. Significant improvements in N ratio can be obtained.

[Brief description of the drawings]

FIG. 1A is a schematic partial plan view showing one embodiment of an imaging device of the present invention. FIG. 2B is a schematic partial cross-sectional view of the schematic plan view of FIG.

2 (a) to 2 (e) are partial schematic sectional views showing one embodiment of a method for manufacturing an image sensor according to claim 5 of the present invention in the order of steps.

3 (a) to 3 (f) are partial schematic sectional views showing one embodiment of a method for manufacturing an image sensor according to claim 6 of the present invention in the order of steps.

FIG. 4 is an explanatory view schematically showing a porous layer formed on a resin lens of the image sensor of the present invention.

FIG. 5 is an explanatory view showing an electron micrograph of a texture of a surface of a porous layer formed on a resin lens of the imaging device of the present invention.

FIG. 6A is a plan view showing a schematic partial plan view of a microlens. (B) is an explanatory view showing a configuration of a resin lens formed on the undercoat layer. (C)
FIG. 4 is an explanatory diagram showing a configuration of a microlens formed on an undercoat layer.

[Explanation of symbols]

Reference Signs List 11 semiconductor substrate 21 photoelectric conversion element 31 light-shielding portion 41, 42 flattening layer 51 color filter 61, 111 undercoat layer 62 concave portion 63 light absorbing layer 71 Resin patterns 71a, 121 Resin lens 81 Porous layer 81a Columnar resin 81b Optical voids (voids) 90, 140 Microlenses 100, 200 Image sensor 131 Transparent resin layer 141 ...... thickness pitch Vt ...... porous layer in the recesses V _P ...... voids

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/335 G02B 1/10 A H01L 31/02 B F term (Reference) 2H042 AA09 AA15 AA21 2K009 AA04 BB11 CC21 DD02 DD12 4M118 AA01 AA05 AB01 BA10 BA14 CA03 GC07 GD04 5C024 CX03 CX41 EX24 EX43 EX52 GX03 GY01 GY31 5F088 BA01 BB03 EA04 HA05 HA20

Claims (6)

[Claims] 1. An imaging device comprising at least a plurality of photoelectric conversion elements, a flattening layer, a color filter, an undercoat layer, and a microlens, wherein the microlens is optically formed on the resin lens and the resin surface. An image sensor comprising a porous layer having voids (voids). 2. The imaging device according to claim 1, wherein voids (voids) and a thickness of the porous layer are approximately λ / 4 of a light wavelength in a visible light region. 3. The imaging device according to claim 1, wherein a concave portion is formed between the microlenses, and a light absorbing layer is provided in the concave portion. 4. The imaging device according to claim 1, wherein the material of the undercoat layer is made of a resin having an etching rate higher than that of a resin constituting the resin lens. . 5. A method for manufacturing an image pickup device, comprising at least the following steps. (A) a photoelectric conversion element, a light shielding portion, a flattening layer,
A step of manufacturing an image pickup device in an intermediate step in which a color filter, a flattening layer, and an undercoat layer are formed. (B) applying a photosensitive material on the undercoat layer,
A step of forming a photosensitive resin layer, and exposing and developing to form a resin pattern. (C) forming a resin lens by heat-flowing the resin pattern. (D) a step of forming a concave portion in the exposed undercoat layer between the resin lenses (e) a transparent resin is applied on the resin lens to form a transparent resin layer, and the transparent resin layer is dry-etched Thereby, a step of forming a porous layer such that the voids (voids) and the thickness of the resin surface become approximately λ / 4 of the wavelength of light, thereby manufacturing an image sensor. 6. A method of manufacturing an image pickup device, comprising at least the following steps. (A) a photoelectric conversion element, a light shielding portion, a flattening layer,
A step of manufacturing an image pickup device in an intermediate step in which a color filter, a flattening layer, and an undercoat layer are formed. (B) applying a photosensitive material on the undercoat layer,
A step of forming a photosensitive resin layer, and exposing and developing to form a resin pattern. (C) forming a resin lens by heat-flowing the resin pattern. (D) forming a concave portion in the exposed undercoat layer between the resin lenses; and (e) applying a black resin containing a light absorbing agent to the resin lens and the concave portion between the resin lenses to form a black resin layer. Removing the black resin layer on the resin lens, and forming a light absorbing layer in a concave portion between the resin lenses. (F) By applying a transparent resin on the resin lens to form a transparent resin layer and dry-etching the transparent resin layer, the voids (voids) and the thickness of the resin surface become approximately λ of the wavelength of light. Forming a porous layer having a thickness of / 4 and manufacturing an image sensor.