JP2022103081A - Solid-state imaging element and manufacturing method of solid-state imaging element - Google Patents

Abstract

To provide a solid-state imaging element and a manufacturing method thereof that can reduce the light that becomes noise in the solid-state imaging pixel, and can realize a high-precision solid-state imaging element.SOLUTION: A solid-state imaging element includes a semiconductor substrate having a plurality of photoelectric conversion elements arranged two-dimensionally, a first optical path layer, a second optical path layer, a light-shielding layer provided between the first optical path layer and the second optical path layer, and a plurality of microlenses two-dimensionally arranged on the surface opposite to the light-shielding layer of the second optical path layer. When the height dimension in the thickness direction of an opening is b, the minimum value of the opening dimension in the direction orthogonal to the thickness direction of the opening is a, and the aspect ratio which is the ratio b/a of the height dimension to the opening dimension, is α, α≥1 and a≥3 μm are satisfied, a pillar structure through which light can be transmitted is formed in the same shape as the opening, and a photosensitive resist constituting the pillar structure is a negative type resist.SELECTED DRAWING: Figure 1

Description

The present invention relates to a solid-state image sensor and a method for manufacturing a solid-state image sensor.

In an authentication device such as an optical fingerprint detection sensor, a fingerprint image is taken using a solid-state image sensor and used for authentication. The solid-state image sensor is provided corresponding to a semiconductor substrate having a plurality of photoelectric conversion elements arranged two-dimensionally and a plurality of photoelectric conversion elements, respectively, and after condensing light from the outside, photoelectric conversion is performed. It includes a plurality of microlenses incident on the element, an optical path layer for transferring the light emitted from the microlenses to the photoelectric conversion element, and a light-shielding layer having an opening through which the light incident on the photoelectric conversion element is passed. For example, see Patent Document 1).

An alignment mark is formed at a suitable portion of such a solid-state image sensor, and this alignment mark is used, for example, for aligning a photomask used when forming an opening of a light-shielding layer. When illuminated with a light source, there is a difference between the light transmitted or reflected at the location where the alignment mark is formed and the light transmitted or reflected at the location where the alignment mark is not formed, and this difference is detected by the optical sensor. The position of the alignment mark is identified by detecting.

Japanese Unexamined Patent Publication No. 2008-168118

The fingerprint detection sensor needs to be enlarged in order to increase the amount of light received by the photoelectric conversion element, but at the same time, light from other than the desired optical path (light path of light useful for fingerprint detection) also increases as noise. However, the detection accuracy is reduced. In order to reduce the light that becomes noise, it is required to increase the thickness of the light-shielding layer to improve the alignment accuracy. However, the material used for the light-shielding layer requires light-shielding performance, and may block the light of the light source used for alignment, which may reduce the alignment accuracy. Further, there is a similar problem when the light-shielding layer is thickened in order to improve the light-shielding performance.

The present invention has been made to solve the above problems, and is a solid-state image pickup device and a solid-state image pickup that can reduce light that becomes noise in a solid-state image pickup pixel and can realize a high-precision solid-state image pickup element. An object of the present invention is to provide a method for manufacturing an element.

The solid-state imaging device according to the first aspect of the present invention includes a semiconductor substrate having a plurality of photoelectric conversion elements arranged two-dimensionally, and a first optical path layer provided on the first surface side of the semiconductor substrate. , A second optical path layer provided on the surface of the first optical path layer opposite to the semiconductor substrate, and a light-shielding layer provided between the first optical path layer and the second optical path layer. And a plurality of microlenses arranged two-dimensionally on the surface of the second optical path layer opposite to the light-shielding layer. The light-shielding layer has an opening for securing an optical path for light incident on the photoelectric conversion element at a position corresponding to the photoelectric conversion element, and has a cross section along the thickness direction of the light-shielding layer and passing through the opening. The height dimension of the opening in the thickness direction is b, the minimum value of the opening dimension in the direction orthogonal to the thickness direction of the opening is a, and the ratio of the height dimension to the opening dimension. When the aspect ratio of b / a is α, α ≧ 1 and a ≧ 3 μm, and the pillar structure through which light can be transmitted is formed in the opening in the same shape as the opening. The photosensitive resist constituting the pillar structure is a negative type resist.

According to the above-mentioned solid-state image sensor, the opening of the light-shielding layer has an opening dimension a ≧ 3 μm along the direction orthogonal to the thickness direction of the light-shielding layer, that is, the minimum dimension is 3 μm and the aspect ratio α is 1 or more. It is configured to be formed, thereby thickening the light-shielding plate for an opening having a predetermined opening size. By thickening the light-shielding layer, light can be reliably blocked, thereby suppressing the transmission of light from the non-opening portion of the light-shielding layer, which causes noise in the solid-state image sensor. Can be reduced.

Further, according to the above-mentioned solid-state image sensor, a pillar structure capable of transmitting light is formed in the opening of the light-shielding layer in the same shape as the opening, and the pillar structure is changed from a microlens to a photoelectric conversion element. It functions as an opening that secures the optical path of the light. Since the pillar structure can be easily formed to be extremely minute or elongated, the opening can be easily formed even if the thickness of the light-shielding layer is increased and the opening is elongated in size. The solid-state image sensor according to the present invention has a pillar structure formed at the opening, and the size of the opening is defined by the pillar structure, so that the solid-state image sensor depends on the resolution of the pigment resist of the light-shielding layer. It is possible to form an opening without.

The pillar structure may have a height that is the sum of the film thicknesses of the first optical path layer, the second optical path layer, and the light-shielding layer.
After forming the plurality of pillar structures configured in this way, the first optical path layer, the light-shielding layer, and the second optical path layer are sequentially laminated on the substrate on which the pillar structure is formed by spray coating, printing, or the like. It can be formed and each layer can be easily formed. Further, when forming each layer, the pillar structure can be used as a positioning reference.

The pillar structure may have the same height as the film thickness of the light-shielding layer.

The solid-state image sensor includes an effective pixel region in which a plurality of pixels for photosensitive imaging are arranged, and an alignment mark is provided on the outer periphery of the effective pixel region, and the height of the alignment mark is lower than the upper surface of the light-shielding layer. It may be formed so as not to become.
By providing the alignment mark, the solid-state image sensor can perform accurate alignment when forming each layer, and in particular, by aligning the photomask used when forming the opening, the accuracy of forming the opening is improved. Therefore, only effective light useful for image formation can be passed through the opening, and light that becomes noise can be reduced.

The alignment mark may be formed of the same material as the pillar structure.
With this configuration, alignment marks can be collectively formed in the process of forming the pillar structure, and the process can be simplified.

The method for manufacturing a solid-state image pickup element according to a second aspect of the present invention is the method for manufacturing the above-mentioned solid-state image pickup element, wherein the aspect ratio, which is the ratio of the height dimension to the width dimension of the pillar structure, is 1 or more. Moreover, the pillar structure forming step in which the pillar structure through which light can be transmitted is formed by the negative type photosensitive resist so that the width dimension is 3 μm or more, and after the pillar structure forming step, the pillar structure is formed. A light-shielding layer forming step of forming the light-shielding layer so as to be included as a filler is included.

In the method for manufacturing a solid-state image sensor according to a second aspect of the present invention, after forming the light-shielding layer, a predetermined thickness of the light-shielding layer is removed so as to expose the pillar structure from the light-shielding layer. The pillar structure may be formed at the same height as the film thickness of the light-shielding layer.

In the method for manufacturing a solid-state imaging device according to another embodiment of the present invention, the first optical path layer, the light-shielding layer, and the second optical path layer are sequentially included so as to include at least a part of the pillar structure as a filler. The step of forming the first optical path layer and the second optical path layer to be formed by laminating is further included, and the first optical path layer, the light-shielding layer, and the second optical path layer are sequentially laminated and formed, and then the above. The predetermined thickness of the second optical path layer is removed so as to expose the pillar structure from the second optical path layer, and the pillar structure is removed from the first optical path layer, the second optical path layer, and the light-shielding layer. It may be formed to the total height of the film thicknesses of.

When the first optical path layer, the light-shielding layer, and the second optical path layer are sequentially laminated and formed, the pillar structure is positioned by positioning the first optical path layer, the light-shielding layer, and the second optical path layer. It may be used as a reference.

An alignment mark forming step of providing an alignment mark on the outer periphery of the effective pixel region of the solid-state image sensor may be further included, and the height of the alignment mark may be formed so as not to be lower than the upper surface of the light-shielding layer.

According to the solid-state image sensor and the method for manufacturing a solid-state image sensor of the present invention, it is possible to reduce light that becomes noise in the solid-state image sensor, and it is possible to realize a high-precision solid-state image sensor.

It is a schematic diagram which shows the structure of the solid-state image sensor which concerns on one Embodiment of this invention. It is a figure of the example which shows the cross-sectional shape of the opening of the light-shielding layer in the solid-state image pickup device which concerns on one Embodiment of this invention. It is a figure of the example which shows the cross-sectional shape of the opening of the light-shielding layer in the solid-state image pickup device which concerns on one Embodiment of this invention. It is a figure of the example which shows the cross-sectional shape of the opening of the light-shielding layer in the solid-state image pickup device which concerns on one Embodiment of this invention. It is a figure of the example which shows the cross-sectional shape of the opening of the light-shielding layer in the solid-state image pickup device which concerns on one Embodiment of this invention. It is a top view which shows the formation position of the alignment mark in the solid-state image pickup device which concerns on the said embodiment of this invention. It is a schematic diagram which shows the structure of the solid-state image sensor which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the manufacturing method which manufactures the solid-state image sensor which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows the process of manufacturing the solid-state image pickup device which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows the process of manufacturing the solid-state image pickup device which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows the process of manufacturing the solid-state image pickup device which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows the process of manufacturing the solid-state image pickup device which concerns on 1st Embodiment of this invention. It is a flowchart which shows the manufacturing method which manufactures the solid-state image sensor which concerns on 2nd Embodiment of this invention. It is a schematic diagram which shows the process of manufacturing the solid-state image pickup device which concerns on 2nd Embodiment of this invention. It is a schematic diagram which shows the process of manufacturing the solid-state image pickup device which concerns on 2nd Embodiment of this invention. It is a schematic diagram which shows the process of manufacturing the solid-state image pickup device which concerns on 2nd Embodiment of this invention.

Hereinafter, the solid-state image pickup device and the manufacturing method thereof according to the present invention will be described with reference to the drawings. The embodiments described herein are optimal embodiments for carrying out the invention, and the present invention is not limited to these embodiments.
Here, the drawings are schematically shown, and the relationship between the thickness of each layer and the plane dimensions, the ratio of the thickness of each layer, and the like may differ from the actual ones. Further, the embodiments shown below exemplify a configuration for embodying the technical idea of the present invention, and the technical idea of the present invention is not limited thereto.

<Structure of the entire solid-state image sensor>
The solid-state image sensor of the present invention comprises a semiconductor substrate having a plurality of photoelectric conversion elements arranged two-dimensionally, a first optical path layer formed on one surface side of the semiconductor substrate, and a first optical path layer. A second optical path layer formed on the surface opposite to the semiconductor substrate, a light-shielding layer formed between the first optical path layer and the second optical path layer, and a light-shielding layer of the second optical path layer. Equipped with a plurality of microlenses arranged two-dimensionally on the opposite surface. Further, in the light-shielding layer, an opening for securing an optical path for light incident on the photoelectric conversion element is formed at a position corresponding to the photoelectric conversion element. Further, in the cross section along the thickness direction of the light-shielding layer and passing through the opening, the height dimension in the thickness direction of the opening is b, and the minimum value of the opening dimension in the direction orthogonal to the thickness direction of the opening is set. When a and the aspect ratio, which is the ratio b / a of the height dimension to the opening dimension, is α, α ≧ 1 and a ≧ 3 μm. Further, in the opening, a pillar structure through which light can be transmitted is formed in the same shape as the opening, and the photosensitive resist constituting the pillar structure is a negative resist.

The solid-state image sensor of the present invention includes an effective pixel region in which a plurality of pixels for photosensitive imaging are arranged, an alignment mark is provided on the outer periphery of the effective pixel region, and the height of the alignment mark is lower than the upper surface of the light-shielding layer. It is formed so that it does not become.

Hereinafter, a specific form of the solid-state image sensor according to the present invention will be specifically described with reference to the drawings.
<Solid image sensor of the first embodiment>
The solid-state image sensor according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a schematic view showing the configuration of a solid-state image sensor according to the first embodiment of the present invention. First, each component of the solid-state image pickup device 1 according to the present embodiment will be schematically described.
As shown in FIG. 1, in the solid-state image sensor 1 according to the present embodiment, the semiconductor substrate 2, the first optical path layer 3, and the light-shielding layer 4 are viewed from the side farther from the subject S (lower side in the figure). A second optical path layer 5 and a microlens 6 are provided in this order.

Specifically, in the solid-state image sensor 1 according to the present embodiment, the first optical path layer 3 is provided on the first surface 2a (upper surface) side of the semiconductor substrate 2. The light-shielding layer 4 is provided on the first surface 3a (upper surface) of the first optical path layer 3 opposite to the semiconductor substrate 2. The second optical path layer 5 is provided on the first surface 4a (upper surface) of the light-shielding layer 4 opposite to the semiconductor substrate 2. The microlens 6 is provided on the first surface 5a (upper surface) of the second optical path layer 5 opposite to the semiconductor substrate 2.

Further, in the solid-state imaging device 1 according to the present embodiment, a plurality of photoelectric conversion elements 21 are two-dimensionally arranged on the semiconductor substrate 2, and the light-shielding layer 4 corresponds to each of the plurality of photoelectric conversion elements 21. A minute opening 41 is formed therein. As shown in FIG. 2, the plurality of openings 41 are formed so as to penetrate from the first surface 4a to the second surface 4b opposite to the first surface 4a in the thickness direction of the light-shielding layer 4.
A plurality of microlenses 6 are two-dimensionally arranged so as to correspond to each of the plurality of photoelectric conversion elements 21 and the plurality of openings 41 described above. The opening 41 is formed with a pillar structure capable of transmitting light and made of a negative photosensitive resist.

Hereinafter, each component of the solid-state image sensor 1 will be specifically described.
<Semiconductor substrate>
As shown in FIG. 1, a plurality of photoelectric conversion elements 21 are two-dimensionally arranged on the semiconductor substrate 2 of the solid-state image pickup device 1 according to the present embodiment. The plurality of photoelectric conversion elements 21 have a function of converting incident light into an electric signal.
The semiconductor substrate 2 on which the photoelectric conversion element 21 is formed is made of a material that allows visible light to pass through and can withstand a temperature of at least about 300 ° C. Here, examples of the material used for the semiconductor substrate 2 include oxides such as Si and SiO2, nitrides such as SiN, and materials containing Si such as a mixture thereof.

<First optical path layer and second optical path layer>
The first optical path layer 3 is formed on the first surface 2a of the semiconductor substrate 2. The second optical path layer 5 is formed above the semiconductor substrate 2. The first optical path layer 3 and the second optical path layer 5 can transmit the light incident from the microlens 6. The transmittance of the first optical path layer 3 and the second optical path layer 5 is preferably 90% or more, more preferably 95% or more with respect to visible light having a wavelength of 400 nm or more and 700 nm or less. One optical path layer 3 and a second optical path layer 5 are formed.

<Micro lens>
The plurality of microlenses 6 are two-dimensionally arranged above the semiconductor substrate 2 so as to correspond to the plurality of photoelectric conversion elements 21 respectively. That is, the microlens 6 is provided at a position corresponding to each of the photoelectric conversion elements 21. The microlens 6 can compensate for the decrease in sensitivity of the photoelectric conversion element 21 by condensing the incident light incident on the microlens 6 on each of the photoelectric conversion elements 21.
The microlens 6 is, for example, one of acrylic resin, epoxy resin, polyimide resin, phenol novolac resin, polyester resin, urethane resin, melamine resin, urea resin, styrene resin, silicon resin and the like. Or it is formed of a resin material containing a plurality. Further, the microlens 6 may be formed of a substance other than the organic compound. Specifically, the microlens 6 contains at least one of silicon, carbon, oxygen, hydrogen, tin, zinc, indium, aluminum, gallium, titanium, molybdenum, tungsten, niobium, tantalum, hafnium, silver and fluorine. It may be formed of a compound, oxide or nitride contained therein. As the compound of these materials, for example, ITO, ZnO, TiO2, HfO2 and the like can be used.

<Shading layer>
The light-shielding layer 4 is made of a pigment resist. The light-shielding coloring material contained in the light-shielding layer 4 has absorbency in the visible light wavelength region and the infrared region, and has a light-shielding function. Further, in the present embodiment, the resist is a coloring composition containing carbon or a pigment, and the light-shielding layer may be a material having photosensitivity or a material having no photosensitivity.

As the color material of the light-shielding layer 4, for example, carbon black, titanium oxide, or the like can be used. As the dyes that can be included in the light-shielding layer 4, for example, azo dyes, anthraquinone dyes, phthalocyanine dyes, quinone imine dyes, quinoline dyes, nitro dyes, carbonyl dyes, methine dyes and the like are used. Can be done. One kind of these light-shielding coloring materials may be used, or two or more kinds may be combined at an appropriate ratio.

As shown in FIG. 1, the light-shielding layer 4 is arranged between the first optical path layer 3 and the second optical path layer 5. Further, the light-shielding layer 4 is formed with minute openings 41 at positions corresponding to the plurality of microlenses 6 and the plurality of photoelectric conversion elements 21.

An opening 41 is formed in the light-shielding layer 4 to secure an optical path for light incident on the photoelectric conversion element 21. Specifically, as shown in FIG. 1, the incident light L incident from the subject S side is incident on the microlens 6, condensed by the microlens 6, and then passed through the second optical path layer 5 to block light. After passing through the opening 41 formed in the layer 4, it is incident on the first optical path layer 3. Finally, the incident light L reaches the photoelectric conversion element 21 formed on the semiconductor substrate 2. As a result, the optical image of the subject S becomes an electric signal after photoelectric conversion, and is used for authentication of personal information such as a fingerprint. On the other hand, in the incident light incident from the subject S side, a part of the incident light is unnecessary light, is incident on the microlens 6 and is condensed, passes through the second optical path layer 5, and then passes through the opening 41 of the light shielding layer 4. It reaches an area other than (light-shielding area). Since the light-shielding layer 4 is composed of a pigment resist having a light-shielding function, a part of the light is shielded by the light-shielding layer 4 and does not enter the photoelectric conversion element 21.

In the solid-state image sensor 1 according to the present embodiment, the thickness of the light-shielding layer 4 is 1.0 μm or more.
In the cross section along the thickness direction of the light-shielding layer 4 (vertical direction in the drawing) and passing through the opening 41, the height dimension of the opening 41 in the thickness direction is b, and the height direction of the opening 41 is the thickness direction. The minimum value of the opening dimension in the direction orthogonal to the opening dimension (width direction, left-right direction in the figure) is a, and the aspect ratio, which is the ratio b / a of the height dimension to the opening dimension, is α. In this case, a ≧ 3 μm and α ≧ 1 are satisfied.

In the solid-state image sensor 1 according to the present embodiment, the cross-sectional shape of the pillar structure 42, which is the cross-sectional shape of the opening 41, can be arbitrarily set according to an actual requirement.
Hereinafter, some forms of the cross-sectional shape of the opening 41 will be specifically shown.

2A to 2D are examples showing the cross-sectional shape of the opening of the light-shielding layer in the solid-state image sensor. As shown in FIG. 2A, the opening 41 is formed in a tubular shape in which the opening dimension in the width direction is constant over the thickness direction. Further, the height dimension of the light-shielding layer 4 in the thickness direction is the same as the height dimension of the pillar structure 42 in the thickness direction.

The shape of the opening 41 is not limited to the tubular shape as shown in FIG. 2A. For example, as shown in FIG. 2B, the opening 41a may be formed in a frustum shape. Specifically, the opening dimension (opening area) in the width direction of the opening 41a is formed so as to increase from the second surface 4b on the semiconductor substrate 2 side toward the first surface 4a in the thickness direction.
As shown in FIG. 2B, the opening 41a may be formed so that the opening size of the opening 41a increases with respect to the distance from the semiconductor substrate 2 in the thickness direction. That is, as shown in FIG. 2B, the opening 41a can be formed in an inverted frustum shape.

Further, as shown in FIG. 2C, in the opening 41c, an inverted frustum-shaped opening 41c1 and a tubular opening 41c2 are laminated in this order from the second surface 4b toward the first surface 4a. It may be a structure. The opening dimension (opening area) in the width direction of the opening 41c1 is formed so as to increase from the second surface 4b of the semiconductor substrate 2 toward the first surface 4a to substantially the center in the thickness direction. The opening size of the opening 41c2 is constant in the thickness direction from substantially the center of the light-shielding layer 4 toward the first surface 4a.
As shown in FIG. 2C, the opening 41c has a structure in which an inverted frustum-shaped opening 41c1 and a tubular opening 41c2 are laminated in order from the semiconductor substrate 2 side, and is located on the light incident side (subject S side). By providing it in the tubular opening 41c2, it is possible to suppress the incident light.

Further, as shown in FIG. 2D, the opening 41d has a structure in which a frustum-shaped opening 41d1 and a tubular opening 41d2 are laminated in this order from the second surface 4b toward the first surface 4a. It may be. The opening dimension of the opening 41d1 in the width direction is formed so as to decrease from the second surface 4b of the semiconductor substrate 2 toward the first surface 4a to substantially the center in the thickness direction. The opening size of the opening 41d2 is constant in the thickness direction from substantially the center of the light-shielding layer 4 toward the first surface 4a.
As shown in FIG. 2D, the opening 41d has a structure in which a cone-shaped opening 41d1 and a tubular opening 41d2 are laminated in order from the semiconductor substrate 2 side, and a cylinder is formed on the light incident side (subject S side). By providing it in the opening 41d2 of the shape, it is possible to suppress the incident light. Further, by providing the frustum-shaped opening 41d1 on the semiconductor substrate 2 side, the incident light can be amplified and the light utilization efficiency can be enhanced.

<Pillar structure>
In the opening 41, a pillar structure 42 is formed as a member different from the opening 41 in the same shape as the opening 41. The pillar structure 42 is made of a material that allows light to pass through, and is made of a negative photosensitive resist. For the pillar structure 42, for example, a linear phenol resin, polymethylmethacrylate, or the like can be used. As shown in FIG. 1, the pillar structure 42 of the present embodiment has the same height as the film thickness of the light-shielding layer 4.

<Alignment mark>
FIG. 3 is a plan view showing the formation position of the alignment mark in the solid-state image sensor according to the present embodiment. When manufacturing a solid-state image sensor, a large number of solid-state image pickup elements are arranged side by side on a single substrate, and then each solid-state image pickup element is divided from the array. FIG. 3 shows a state in which the solid-state image pickup device 1 is not divided after being manufactured, and a total of four solid-state image pickup devices 1 are arranged in a 2 × 2 matrix in the figure.

In the present embodiment, as shown in FIG. 3, the solid-state imaging device includes an effective pixel region 11 in which a plurality of pixels for photosensitive imaging are arranged, and a frame region 12 surrounding the effective pixel region. An alignment mark 7 is provided on the 12th.
Further, the alignment mark 7 may be provided in the region between the solid-state image pickup devices. In either case, the alignment mark 7 may be provided on the outer periphery of the effective pixel region 11 and may play a role of alignment.

FIG. 3 shows that the alignment mark 7 is provided in the frame area 12. FIG. 1 shows that the height of the alignment mark 7 is substantially flush with the upper surface of the light-shielding layer. The height of the alignment mark 7 may not be lower than the upper surface 4a of the light-shielding layer 4, and may be higher than the upper surface 4a of the light-shielding layer 4. As a result, even if the light-shielding layer is formed in the manufacturing process, it can be guaranteed that the alignment mark 7 is exposed from the light-shielding layer 4, so that the alignment mark is not masked by the light-shielding layer and can be reliably identified. Can play the role of alignment.

The alignment mark 7 may be formed by using the same material as the pillar structure 42, or may be formed by using a material different from the pillar structure 42. When the same material as the pillar structure 42 is used, it can be collectively formed by the step of forming the pillar structure, which is preferable because the step can be simplified.

<Solid image sensor of the second embodiment>
FIG. 4 is a schematic view showing the configuration of the solid-state image sensor 1A according to the second embodiment of the present invention. This embodiment is different from the first embodiment in that the height of the pillar structure is different from that of the first embodiment and the second optical path layer 5 is provided on the alignment mark 7A, and the other configurations are different from the first embodiment. Are similar, so duplicate explanations will be omitted.
In FIG. 4, the pillar structure 42 has a total height of the film thicknesses of the first optical path layer 3, the light-shielding layer 4, and the second optical path layer 5. That is, the pillar structure 42 is formed from the upper surface 2a of the semiconductor substrate 2 to the upper surface 5a of the second optical path layer 5.
The alignment mark 7A has a total height of the first optical path layer 3 and the light-shielding layer 4.
The configuration of the solid-state image pickup devices 1 and 1A of the present invention has been described above by taking the first embodiment and the second embodiment as examples. Next, the effects obtained based on the solid-state image pickup devices 1 and 1A configured in this way will be described.

<Effect>
The solid-state image sensor 1 according to the first embodiment can obtain the following effects by having the above-mentioned components.
In the solid-state image sensor 1 according to the present invention, the opening of the light-shielding layer has an opening dimension a ≧ 3 μm in a direction orthogonal to the thickness direction of the light-shielding layer, that is, the minimum dimension is 3 μm and the aspect ratio α is 1. By being configured as described above, the thickness of the light-shielding layer is increased with respect to the opening having a predetermined opening size. By increasing the thickness of the light-shielding layer, light can be reliably blocked, thereby suppressing the transmission of light from the non-opening portion of the light-shielding layer, which causes noise in the solid-state image sensor. Can be reduced.

In the solid-state image sensor 1 according to the present invention, the opening 41 of the light-shielding layer 4 has a pillar structure having the same shape as the opening 41 and capable of transmitting light, and the pillar structure 42 is the microlens 6. It functions as an opening 41 for securing an optical path of light from the light to the photoelectric conversion element 21. Since the pillar structure 42 can be easily formed to be extremely minute or elongated, the opening 41 can be easily formed even if the thickness of the light-shielding layer 4 is increased and the opening 41 is elongated in size. In the solid-state image sensor 1 according to the present invention, the pillar structure 42 is formed in the opening 41, and the size of the opening 41 is defined by the pillar structure 42, so that the pigment resist of the light-shielding layer 4 is solved. The opening 41 can be formed without depending on the image quality.

In the solid-state image sensor 1 according to the present invention, since the pillar structure is formed of a negative photosensitive resist, it has the advantages of strong adhesive force, high sensitivity, and less stringent requirements for development conditions.
By providing the alignment mark 7 in the solid-state image pickup device 1 according to the present invention, accurate alignment can be performed when forming each layer. In particular, by aligning the photomask used when forming the aperture, the accuracy of forming the aperture can be improved, and only the effective light useful for imaging can pass through the aperture, reducing the light that becomes noise. can do.

In the solid-state image sensor 1 according to the present invention, since the alignment mark 7 is formed of the same material as the pillar structure 42, the alignment mark 7 can be collectively formed in the process of forming the pillar structure 42, which simplifies the process. can do.
In the solid-state image pickup device 1 according to the present invention, if the opening size of the opening 41 is set to be constant over the thickness direction, the opening 41 can be easily formed.
In the solid-state image pickup device 1 according to the present invention, if the opening dimension of the opening 41a is provided so as to increase as the distance from the semiconductor substrate increases in the thickness direction, the incident of scattered light can be suppressed on the incident side of the light.
In the solid-state image sensor 1 according to the present invention, if the opening 41a is formed in a frustum shape, the incident light can be amplified and the light utilization efficiency can be enhanced.
In the solid-state image sensor 1 according to the present invention, when the opening 41c is provided in a structure in which an inverted cone shape and a tubular shape are laminated in order from the semiconductor substrate 2 side, when the opening is provided in a tubular shape on the incident side of light. The incident light can be suppressed, and when the opening is provided in a cone shape on the semiconductor layer side, the incident light can be amplified and the light utilization efficiency can be enhanced.

The solid-state image sensor 1A according to the second embodiment can obtain the following effects in addition to the above-mentioned effects.
After forming the plurality of pillar structures 42A, the first optical path layer 3, the light-shielding layer 4, and the second optical path layer 5 are sequentially laminated on the substrate on which the pillar structure 42A is formed by spray coating, printing, or the like. In this case, the pillar structure can be used as a positioning reference.

<Manufacturing method of solid-state image sensor>
FIG. 5 is a flowchart showing a manufacturing method for manufacturing the solid-state image sensor 1 according to the first embodiment of the present invention, and FIG. 6 shows a process of manufacturing the solid-state image sensor 1 according to the first embodiment of the present invention. It is a schematic diagram.
Hereinafter, the method for manufacturing the solid-state image sensor 1 according to the first embodiment will be described with reference to FIGS. 5 and 6.

In the method for manufacturing the solid-state image sensor 1 according to the first embodiment, known methods can be used for manufacturing the semiconductor substrate 2, the first optical path layer 3, the second optical path layer 5, and the microlens 6. , Hereinafter, the detailed description thereof will be omitted, and only the part having the characteristic point with respect to the prior art in the manufacturing method will be described.

As shown in FIG. 5, the method for manufacturing the solid-state imaging device according to the first embodiment uses a negative photosensitive resist such as linear phenol resin or polymethylmethacrylate, and is a ratio of the height dimension to the width dimension. After the pillar structure forming step of forming a pillar structure through which light can be transmitted and the pillar structure forming step so that the aspect ratio α is 1 or more and the opening dimension a is 3 μm or more, the pillar structure is included as a filler. Mainly includes a light-shielding layer forming step S2 for forming a light-shielding layer. Further, the alignment mark forming step S3 is executed at the same time as the pillar structure forming step S1 to form the alignment mark by the same material and method as the pillar structure.

Next, the pillar structure forming step S1 will be specifically described.
FIG. 6 is a schematic view showing a pillar structure forming step S1 and a light shielding layer forming step S2.
In the pillar structure forming step S1, a step S11 (FIG. 6A) for forming a negative type photosensitive resist layer and a step S12 (FIG. 6B) for removing a predetermined portion of the photosensitive resist layer to leave only the pillar structure are performed. Mainly included.

Next, an example of the pillar structure forming step S1 will be specifically described. In the method for manufacturing the solid-state image sensor 1 of the present invention, a negative type lesbian is used as the photosensitive resist.
In the pillar structure forming step S1, for example, in step S11, a coating step of applying a negative-type photosensitive resist to the substrate 45 and a coating step of rotating the substrate 45 to dry the applied photosensitive resist to form a photosensitive resist film. A drying step of forming the 46 and a prebaking step of prebaking the photosensitive resist film 46 are included, and in step S12, an exposure step of exposing the prebaked photosensitive resist film 46 with a mask having a predetermined pattern. , The photosensitive resist film 46 is developed with a developing solution, and only a predetermined portion is left as a pillar structure (here, since the applied is a negative type photosensitive resist, it is irradiated with light through a mask. The development step (which is left as a pillar structure), the cleaning step of cleaning the substrate 45 where the pillar structure remains, the drying step of rotating the substrate 45 to dry it, and hard baking the pillar structure. Includes a hard bake process for post-baking.
In the method for manufacturing the solid-state image sensor 1 of the present invention, the photosensitive resist film 46 is exposed using a mask, and the tubular photosensitive resist film 46a has a cylindrical photosensitive resist film 46a as a pillar structure. It is left as an alignment mark 7.

In the exposure step in step S12, light is also irradiated to a predetermined position on the outer periphery of the photosensitive resist film via a mask, and after the above-mentioned development step, the photosensitive resist film 46b irradiated with light is used as an alignment mark. By being left behind, an alignment mark (photosensitive resist film 46b) was also formed outside the pillar structure 42 by using the same material as the pillar structure 42 in the same process as the pillar structure forming step S1 (alignment mark formation). Step S3). Here, the formation position of the alignment mark is set according to the specifications of the solid-state image pickup device to be formed, and is set so as to be located on the outer periphery of the effective pixel region of the solid-state image pickup device.

In the pillar structure forming step S1, the photosensitive resist is exposed using a gray scale mask. In this way, the pillar structure is formed in an inverted frustum shape in which the width dimension increases as the distance from the semiconductor substrate 2 increases in the height direction of the light-shielding layer 4. As a result, as shown in FIG. 2B, the pillar structure 42 having a frustum-shaped cross section can be formed.

In the pillar structure forming step S1, the first pillar structure forming step for forming the first layer and the second pillar structure forming for forming the second layer so as to overlap the first layer after the first layer is cured. It may be configured to include steps. The pillar structure thus formed is a laminated structure including at least a first layer and a second layer. In this case, for example, the first layer has the configuration shown in FIG. 2B formed by using a gray scale mask, the second layer has the configuration shown in FIG. 2A, and the pillar has the cross-sectional shape shown in FIG. 2C. The structure can be formed. Further, the first layer has an inverted frustum shape having the configuration shown in FIG. 2B (that is, a frustum shape in which the opening dimension (opening area) decreases from the second surface 4b toward the first surface 4a). The second layer has the configuration shown in FIG. 2B, and a pillar structure having a cross-sectional shape shown in FIG. 2D can also be formed.

Next, an example of the light-shielding layer forming step S2 will be specifically described.
In the light-shielding layer forming step S2, the light-shielding material film forming step S21 (FIG. 6C) for forming the light-shielding material film 47 so as to embed the pillar structure 42, and the pillar structure 42 and the alignment mark 7 are exposed from the light-shielding material film 47. Mainly includes a light-shielding material film removing step S22 (FIG. 6D) for removing a predetermined thickness of the light-shielding material film 47.
Specifically, the light-shielding layer forming step S2 includes a coating step of applying a light-shielding material so as to embed the pillar structure 42, a drying step of drying the applied light-shielding material to form a light-shielding material film 47, and a light-shielding material film. A pre-baking step of prebaking 47 and a light-shielding material film removing step of removing a predetermined thickness of the light-shielding material film 47 so as to expose the pillar structure 42 and the alignment mark 7 from the light-shielding material film 47 to form the light-shielding material film 4. including. Further, the pillar structure is formed at the same height as the film thickness of the light-shielding layer, and the height of the alignment mark 7 is formed so as not to be lower than the upper surface 4a of the light-shielding layer 4.

When the light-shielding material film 47 is a photosensitive material, the light-shielding material film removing step includes an exposure step of exposing the light-shielding material film 47 using a mask having a predetermined pattern and a light-shielding material film 47 using a developing solution. The present invention includes a development step of removing a predetermined thickness of the light-shielding material film 47 so as to expose the pillar structure 42 from the light-shielding material film 47.
When the light-shielding material film 47 is a non-photosensitive material, the light-shielding material film removing step includes a dry etching step of removing a predetermined thickness of the light-shielding material film 47 by dry etching.
After the step S22, in order to form the solid-state image sensor 1, it is necessary to further arrange the first optical path layer 3, the second optical path layer 5, the microlens 6, and the like, and at this time, the alignment mark 7 is used. Alignment can be done.

As described above, as a method for manufacturing the solid-state image sensor 1, an example of the pillar structure forming step S1 and the light-shielding layer forming step S2 has been described. These steps are an example, in which the pillar structure 42 is formed so that the aspect ratio, which is the ratio of the height dimension to the width dimension, is 1 or more and the width dimension is 3 μm or more, and the effective pixel region of the solid-state image sensor 1 is formed. The alignment mark 7 may be formed on the outer periphery of the above, and the specific process is not limited to this.

Hereinafter, the method for manufacturing the solid-state image sensor according to the second embodiment will be described with reference to FIGS. 7 and 8A to 8C.
FIG. 7 is a flowchart showing a manufacturing method for manufacturing the solid-state image sensor according to the second embodiment of the present invention, and FIG. 8 is a schematic view showing a process of manufacturing the solid-state image sensor according to the second embodiment of the present invention. be.

Since the pillar structure forming step S1A and the alignment mark forming step S3A in the method for manufacturing the solid-state image sensor according to the second embodiment are the same as the pillar structure forming step S1 and the alignment mark forming step S3 according to the first embodiment, they overlap. The explanation to be done is omitted. Also, the pillar structure is formed higher than in the first embodiment.
As shown in FIG. 7, in the laminating step S2A, the first optical path layer 3, the light shielding layer 4, and the second optical path layer 5 laminating step (step S21A) are sequentially performed so as to include at least a part of the pillar structure as a filler. It is formed by laminating, and at this time, the light-shielding layer 4 is formed so that the height of the alignment mark 7A is not lower than the upper surface 4a of the light-shielding layer 4, that is, the alignment mark is exposed from the light-shielding layer and can be identified. do. After that, the predetermined thickness of the second optical path layer is removed, and the pillar structure is formed to the total thickness of the film thicknesses of the first optical path layer, the light-shielding layer, and the second optical path layer (S22A).

As shown in FIGS. 8A to 8C, the pillar structure 51a (42A) and the alignment mark 51b (7A) are formed in the step S21A. Then, in FIG. 8C, the mask is positioned based on the alignment mark 7, and the first optical path layer 3 and the light-shielding layer 4 are sequentially applied to the substrate 50 on which the pillar structure is formed via the mask. Apply the light-shielding layer 4 to a thickness that allows the alignment mark 7 to be exposed. Next, using the alignment mark 7 and the pillar structure 42A as the alignment reference, the second optical path layer 5 is further applied, and finally three layers of the first optical path layer 3, the light shielding layer 4, and the second optical path layer 5 are applied. Laminated structure was formed.

Next, in step S22A, although not shown, the predetermined thickness of the second optical path layer 5 is removed, and the pillar structure 42A is provided with the first optical path layer 3, the light shielding layer 4, and the second optical path layer 5. It is formed to the total thickness of the film thicknesses of. Here, the pillar structure 42A is formed so as to be exposed from the upper surface 5a of the second optical path layer 5. Alternatively, the pillar structure 42A and the second optical path layer 5 are formed of different materials that are visually distinguishable.

After the step S22A, in order to form the solid-state image sensor 1, it is necessary to further arrange the microlens 6 on the second optical path layer 5 or to perform the electrode opening by etching. At this time, in addition to being able to perform alignment using the alignment mark 7, the pillar structure 42A can also be used as an alignment reference between the microlens 6 and the light-shielding layer 4, and the pillar structure 42A is provided with an electrode opening. It can be used as a reference for alignment.
Further, in the method for manufacturing the solid-state imaging devices 1 and 1A according to the first and second embodiments described above, it has been described that the alignment mark is formed in the same process as the pillar structure forming step with the same material as the pillar structure. The mark may be formed in a different process using a material different from the pillar structure.

In the method for manufacturing a solid-state image sensor according to the second embodiment described above, since the pillar structure can play a role of alignment, the formation of an alignment mark can be omitted.

The method for manufacturing the solid-state image pickup devices 1 and 1A according to the first embodiment and the second embodiment described above can obtain the following effects in addition to the effects of the solid-state image pickup devices 1 and 1A described above.
In the same process as the pillar structure forming step, the alignment marks 7 and 7A can be formed from the same material as the pillar structures 42 and 42A, and the process can be simplified.
By forming the pillar structure 42A so as to be exposed from the upper surface 5a of the second optical path layer 5, or by forming the pillar structure 42A and the second optical path layer 5 so as to be formed of different materials that are visually distinguishable. , The pillar structure 42A can play a role of alignment, and at this time, the formation of the alignment mark 7 can be omitted.

Although the specific embodiments of the solid-state image sensor and the method for manufacturing the solid-state image sensor according to the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. The novel embodiment can be implemented in various other embodiments, and various omissions, substitutions and changes of components can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1,1A ... Solid-state image sensor 2 ... Semiconductor substrate 3 ... First optical path layer 4 ... Light-shielding layer 5 ... Second optical path layer 6 ... Microlens 7,7A ... Alignment mark 11 ... Effective pixel area 21 ... Photoelectric conversion element 41 … Opening 42, 42A… Pillar structure

Claims (10)

A semiconductor substrate having a plurality of photoelectric conversion elements arranged two-dimensionally,
The first optical path layer provided on the first surface side of the semiconductor substrate and
A second optical path layer provided on a surface of the first optical path layer opposite to the semiconductor substrate, and
A light-shielding layer provided between the first optical path layer and the second optical path layer,
A plurality of microlenses two-dimensionally arranged on a surface of the second optical path layer opposite to the light-shielding layer are provided.
In the light-shielding layer, an opening for securing an optical path for light incident on the photoelectric conversion element is formed at a position corresponding to the photoelectric conversion element.
In the cross section along the thickness direction of the light-shielding layer and passing through the opening, the height dimension of the opening in the thickness direction is b, and the opening dimension in the direction orthogonal to the thickness direction of the opening. When the aspect ratio, which is the ratio b / a of the height dimension to the opening dimension, is α, α ≧ 1 and a ≧ 3 μm.
In the opening, a pillar structure through which light can be transmitted is formed in the same shape as the opening.
A solid-state imaging device in which the photosensitive resist constituting the pillar structure is a negative resist. The pillar structure has a height obtained by adding the film thicknesses of the first optical path layer, the second optical path layer, and the light-shielding layer.
The solid-state image sensor according to claim 1. The pillar structure has the same height as the film thickness of the light-shielding layer.
The solid-state image sensor according to claim 1. The solid-state image sensor includes an effective pixel region in which a plurality of pixels for photosensitive imaging are arranged.
An alignment mark is provided on the outer periphery of the effective pixel area, and an alignment mark is provided.
The height of the alignment mark is formed so as not to be lower than the upper surface of the light shielding layer.
The solid-state image sensor according to claim 1. The alignment mark is made of the same material as the pillar structure.
The solid-state image sensor according to claim 4. The method for manufacturing a solid-state image sensor according to any one of claims 1 to 5.
The pillar structure capable of transmitting light is formed by a negative photosensitive resist so that the aspect ratio, which is the ratio of the height dimension to the width dimension of the pillar structure, is 1 or more and the width dimension is 3 μm or more. Pillar structure formation process and
After the pillar structure forming step, the light-shielding layer forming step of forming the light-shielding layer so as to include the pillar structure as a filler is included.
A method for manufacturing a solid-state image sensor. After forming the light-shielding layer, a predetermined thickness of the light-shielding layer is removed so that the pillar structure is exposed from the light-shielding layer, and the pillar structure is formed at the same height as the film thickness of the light-shielding layer. ,
The method for manufacturing a solid-state image sensor according to claim 6. Further, a step of forming the first optical path layer and the second optical path layer formed by sequentially laminating the first optical path layer, the light shielding layer, and the second optical path layer so as to include the pillar structure as a filler. Including,
After forming the first optical path layer, the light-shielding layer, and the second optical path layer by laminating them in this order, a predetermined position of the second optical path layer so as to expose the pillar structure from the second optical path layer. The thickness is removed to form the pillar structure at the total height of the thicknesses of the first optical path layer, the second optical path layer, and the light-shielding layer.
The method for manufacturing a solid-state image sensor according to claim 6. When the first optical path layer, the light-shielding layer, and the second optical path layer are sequentially laminated and formed, the pillar structure is positioned by positioning the first optical path layer, the light-shielding layer, and the second optical path layer. Used as a reference,
The method for manufacturing a solid-state image sensor according to claim 8. Further, an alignment mark forming step of providing an alignment mark on the outer periphery of the effective pixel region of the solid-state image sensor is included.
The method for manufacturing a solid-state image sensor according to claim 6, wherein the height of the alignment mark is formed so as not to be lower than the upper surface of the light-shielding layer.

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