JPH07176708A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To improve sensitivity and color reproduction in solid-state image pickup device, by causing full-color light to reach a light-receiving part effectively. CONSTITUTION:A first microlens layer 7A, a second microlens layer 7B, and a third microlens layer 7C are adjusted in height so that the full-color light passing through a color filter layer 5 of red, green, and blue is focused on each corresponding light-receiving part 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device,
In particular, the present invention relates to a solid-state imaging device having a microlens layer effective for improving sensitivity and color reproducibility.

[0002]

2. Description of the Related Art In recent years, as a method of forming a color filter and a microlens in a solid-state image pickup device, a method of directly forming a color filter or a microlens on a wafer (on-chip filter) has become mainstream.

A conventional solid-state image pickup device will be described below.

FIG. 4 shows a sectional structure of a conventional solid-state image pickup device. In FIG. 4, 1 is a semiconductor substrate made of silicon, 2 is a light receiving portion made of a photodiode, 3 is a light shielding portion made of aluminum, and 4 is a light receiving portion. A flattening layer made of an acrylic transparent resin, 5 is made of a gelatin type resin and has a predetermined color,
For example, a color filter layer dyed red, green or blue, 6 is an intermediate layer made of an acrylic transparent resin, and 7 is a microlens layer made of a phenolic resin and formed in the same shape.

The operation of the solid-state image pickup device configured as described above will be described below.

First, not only above the light receiving portion 2 but also the light shielding portion 3
The incident light which has entered also above the light passes through the microlens layer 7, is condensed, and then reaches the color filter layer 5 through the intermediate layer 6. Then, only light having a predetermined wavelength corresponding to the color of the color filter layer 5 is
After passing through, the light enters the light receiving portion 2 through the flattening layer 4. The light incident on the light receiving portion 2 is converted into signal charges in the light receiving portion 2 according to the amount of light.

[0007]

However, the above-mentioned conventional solid-state image pickup device has the following problems. That is, the wavelength of light incident on the microlens layer 7 varies, and the refractive index of light in the microlens layer 7 differs depending on the wavelength of light.

The focal length f of the microlens layer 7 is generally expressed by f = nr / (n-1). Where n;
Refractive index, r; curvature of the microlens layer.

Therefore, if the refractive index of light is different, the focal length is also different. Further, as the solid-state imaging device is downsized and the number of pixels is increased, the area of the light receiving portion 2, that is, the area of the opening of the light shielding portion 3 is reduced. Therefore, visible light (wavelength:
It becomes difficult to make all the light of 400 to 700 nm) enter the light receiving unit 2.

The above reason will be described below with reference to FIG. That is, in the conventional solid-state imaging device, the shape of the microlens layer 7 is the same regardless of the color of the color filter layer 5. Therefore, as shown in FIG. 4, when the shape of the microlens layer 7 is designed so that the green light enters the light receiving portion 2 most efficiently, the light receiving portion corresponding to the green color filter layer 5 is formed. 2 is effectively incident on the red or blue color filter layer 5, but only the red or blue light having a different focal length from the green light reaches the light receiving part 2 corresponding to the red or blue color filter layer 5. However, there is a problem in that light cannot be effectively collected on the light receiving section 2 corresponding to the color filter layer 5 of FIG.

In view of the above, it is an object of the present invention to improve the sensitivity and color reproducibility of a solid-state image pickup device by allowing light of all colors to efficiently reach the light receiving portion.

[0012]

In order to achieve the above-mentioned object, the present invention is such that the focal point of incident light focused by each microlens layer is formed on the corresponding light receiving portion. .

Specifically, the means for solving the problems according to the first aspect of the invention is to provide a plurality of light receiving portions provided on a semiconductor substrate, and a light receiving portion provided corresponding to each of the plurality of light receiving portions to receive incident light. Assuming a solid-state imaging device including a microlens layer for condensing light on a light receiving portion, the shape or material of each microlens layer is set on the light receiving portion to which the focus of incident light condensed by the microlens layer corresponds. The respective configurations are set so as to be formed in the above.

Further, a solution means provided by the invention of claim 2 is that a plurality of light receiving portions provided on the semiconductor substrate and light receiving portions provided corresponding to the plurality of light receiving portions and corresponding to incident light. Assuming a solid-state image pickup device including a microlens layer for condensing light on the surface of each microlens layer, the distance from the lower surface of each microlens layer to the corresponding light receiving portion is such that the focus of incident light condensed by the microlens layer is The configuration is such that each is set so as to be formed on the corresponding light receiving portion.

[0015]

According to the structure of claim 1, the shape or material of each microlens layer is set so that the focal point of the incident light condensed by the microlens layer is formed on the corresponding light receiving portion. Therefore, the light incident on each microlens layer efficiently reaches the light receiving portion.

According to the structure of claim 2, the distance from the lower surface of each microlens layer to the corresponding light receiving portion is such that the focal point of the incident light focused by the microlens layer is formed on the corresponding light receiving portion. The light incident on each microlens layer efficiently reaches the light receiving portion.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a sectional structure of the solid-state image pickup device according to the first embodiment. In FIG. 1, 1 is a semiconductor substrate made of silicon, 2 is a light receiving portion made of a photodiode, and 3 is a photodiode.
Is a light-shielding portion made of aluminum, 4 is a flattening layer made of an acrylic transparent resin, 5 is a gelatin-based resin, and is a color filter layer dyed in a predetermined color, for example, red, green or blue, 6 is an acrylic transparent An intermediate layer made of resin, 7A is a first microlens layer provided above the color filter layer dyed in red, and 7B is a second microlens provided above the color filter layer dyed in green. Layer 7C is a third microlens layer provided above the blue-colored color filter layer, and the first, second and third microlens layers 7A, 7B and 7C are all phenolic resins. Consists of. Further, in the first embodiment, the distance from the upper surface of the light receiving portion 2 to the upper end surface of the intermediate layer 6 is set to 6 μm.

The first, second and third microlens layers 7
The phenol resin constituting A, 7B, and 7C has a refractive index of 1.558 for red light, a refractive index of 1.560 for green light, and a refractive index of 1.562 for blue light. Therefore, as a feature of the first embodiment, the first microlens layer 7A has a spherical shape with a width of 6 μm and a height of 2.510 μm, and the second microlens layer 7B has a width of 6 μm and a height of 2. The third microlens layer 7C is formed in a spherical shape having a diameter of 498 μm and a width of 6 μm and a height of 2.486 μm.

The operation of the solid-state image pickup device having the above structure will be described below.

FIG. 1 shows a state when light is incident on the solid-state image pickup device according to the first embodiment.

First, not only above the light receiving portion 2 but also the light shielding portion 3
The incident light that has entered also above passes through the first to third microlens layers 7A to 7C, is condensed, and then reaches the color filter layer 5 through the intermediate layer 6. Then, only light having a predetermined wavelength corresponding to the color of the color filter layer 5 passes through the color filter layer 5, and then passes through the flattening layer 4 and enters the light receiving unit 2. In this case, since the heights of the first to third microlens layers 7A to 7C are set as described above, the focus of each light passing through the color filter layer 5 is the corresponding light receiving portion 2 Formed on. Therefore, the light passing through the color filter layer 5 is effectively incident on the light receiving section 2, and the sensitivity and color reproducibility of the solid-state imaging device are improved.

Further, the first to third microlens layers 7A
7A to 7C selectively cause light having a specific wavelength to enter the light receiving unit 2, these first to third microlens layers 7A to 7C are included.
C also serves as a color filter. Therefore,
The first to third microlens layers 7A to 7C can supplement the spectral characteristics of the color filter layer 5, and the process margin of the color filter layer 5 increases.

As described above, according to the first embodiment, the light having a predetermined wavelength corresponding to the color of the color filter layer 5 is effectively incident on the light receiving section 2, so that the sensitivity of the solid-state image pickup device and Color reproducibility is improved.

A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a sectional structure of a solid-state image pickup device according to the second embodiment. In FIG. 2, 1 is a semiconductor substrate made of silicon, 2 is a light receiving portion made of a photodiode, and 3 is a photodiode.
Is a light-shielding part made of aluminum, 4 is a flattening layer made of an acrylic transparent resin, 6 is an intermediate layer made of an acrylic transparent resin, and 7A, 7B and 7C are first, second and third layers made of a phenol resin, respectively. It is a microlens layer.
Also in the second embodiment, the distance from the surface of the light receiving portion 2 to the upper end surface of the intermediate layer 6 is set to 6 μm.

The first, second and third microlens layers 7
The phenolic resin constituting A, 7B, and 7C has a red light refractive index of 1.558, a green light refractive index of 1.560, and a blue light refractive index of 1.562. Therefore, also in the second embodiment, as in the first embodiment, the first microlens layer 7A has a spherical shape with a width of 6 μm and a height of 2.510 μm, and the second microlens layer 7B has a width. Is 6 μm and the height is 2.498 μm, and the third microlens layer 7C has a width of 6 μm and a height of 2.4.
Each is formed in a spherical shape of 86 μm.

A feature of the second embodiment is that the color filter layer 5 provided in the first embodiment is not formed and the intermediate layer 6 is formed on the flattening layer 4.

The operation of the solid-state image pickup device having the above structure will be described below.

FIG. 2 shows a state when light is incident on the solid-state image pickup device according to the second embodiment.

First, not only above the light receiving portion 2 but also the light shielding portion 3
The incident light that has also entered above the light source is condensed through the first to third microlens layers 7A to 7C, and then enters the light receiving unit 2 through the intermediate layer 6 and the flattening layer 4. In this case, since the heights of the first to third microlens layers 7A to 7C are set as described above, the first microlens layer 7 is formed.
Of the light passing through A, the focus of red light is formed on the light receiving portion 2 below the first microlens layer 7A, and the focus of green light is formed on the light receiving portion 2 below the second microlens layer 7B. The focus of blue light is the third microlens layer 7
It is formed in the light receiving portion 2 below C. Therefore, the red light, the green light, or the blue light is selected and made incident on the respective light receiving portions 2.

Therefore, according to the solid-state image pickup device according to the second embodiment, color separation can be performed for each light-receiving unit 2, so that the solid-state image pickup device can be operated without forming a color filter layer. it can.

In the first and second embodiments, the heights of the first to third microlens layers 7A to 7C are changed to change the heights of the first to third microlens layers 7A.
The focal points of the light passing through 7C are formed on the corresponding light receiving portions 2, respectively.
By changing the width of the third microlens layers 7A to 7C, or by changing the material of the first to third microlens layers 7A to 7C to change the refractive index, the first to third microlens layers The focal points of the light passing through 7A to 7C may be formed on the corresponding light receiving portions 2.

Further, in the first embodiment, the first to third microlens layers 7A are arranged so that the light having the wavelength of the color of the color filter layer 5 is effectively incident on the light receiving portion 2.
Although the shapes of ˜7C are designed, conversely, it is possible to control the light amount of the light incident on the light receiving section 2 by changing the shapes or materials of the first to third microlens layers 7A to 7C. . This allows control of color characteristics.

The third embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows a sectional structure of a solid-state image pickup device according to the third embodiment. In FIG. 3, 1 is a semiconductor substrate made of silicon, 2 is a light receiving portion made of a photodiode, and 3 is a photodiode.
Is a light-shielding part made of aluminum, 4 is a flattening layer made of an acrylic transparent resin, 5 is a gelatin type resin, and a color filter layer dyed in a predetermined color, for example, red, green or blue, 6A, 6B and 6C. Are first, second and third intermediate layers each made of an acrylic transparent resin, and 7 is a microlens layer made of a phenolic resin.

A feature of the third embodiment is that the heights of the first, second and third intermediate layers 6A, 6B and 6C are such that the light passing through the color filter layer 5 dyed red, green or blue. Are set to be formed on the corresponding light receiving portions 2, respectively. That is, in the third embodiment, by changing the distance from the microlens layer 7 to the light receiving portion 2 without changing the shape or material of the microlens layer 7, the focus of the light passing through each microlens layer 7 is changed. Each of them is formed on the corresponding light receiving portion 2.

By doing so, the first or second
Similarly to the embodiment described above, since light having a predetermined wavelength corresponding to the color of the color filter layer 5 is effectively incident on the light receiving section 2, the sensitivity and color reproducibility of the solid-state imaging device are improved.

[0039]

According to the solid-state image pickup device of the first aspect of the present invention, the shape or material of each microlens layer is formed on the light receiving portion to which the focus of the incident light focused by the microlens layer corresponds. Since the light is incident on each microlens layer efficiently reaches the light receiving portion, the sensitivity and color reproducibility of the solid-state imaging device are improved.

According to the solid-state imaging device of the second aspect of the present invention, the distance from the lower surface of each microlens layer to the corresponding light-receiving portion corresponds to the light-receiving portion to which the focal point of the incident light focused by the microlens layer corresponds. Since the light is incident on each microlens layer efficiently because it is set so as to be formed above, the sensitivity and color reproducibility of the solid-state imaging device are improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a solid-state imaging device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a solid-state imaging device according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a solid-state imaging device according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a conventional solid-state imaging device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Light receiving part 3 Light-shielding part 4 Flattening layer 5 Color filter layer 6 Intermediate layer 6A First intermediate layer 6B Second intermediate layer 6C Third intermediate layer 7 Microlens layer 7A First microlens layer 7B Second microlens layer 7C Third microlens layer

Claims (2)

[Claims] 1. A plurality of light receiving portions provided on a semiconductor substrate, and a microlens layer which is provided corresponding to each of the plurality of light receiving portions and collects incident light on the corresponding light receiving portion. In the provided solid-state imaging device, the shape or material of each microlens layer is set so that the focus of incident light condensed by the microlens layer is formed on the corresponding light receiving portion. Solid-state imaging device. 2. A plurality of light receiving portions provided on a semiconductor substrate, and a microlens layer which is provided corresponding to each of the plurality of light receiving portions and collects incident light on the corresponding light receiving portion. In the provided solid-state imaging device, the distance from the lower surface of each microlens layer to the corresponding light receiving portion is set so that the focal point of the incident light condensed by the microlens layer is formed on the corresponding light receiving portion. A solid-state imaging device characterized by being provided.