JP2000260968A - Solid-state imaging device and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To provide a solid-state imaging device capable of improving sensitivity of all colors and improving a color reproduction area. The size of a microlens formed on a color filter of one color has a different structure from the size of a microlens formed on a color filter of another color. For example, by increasing the spectral sensitivity by making the size of the microlens 10 (blue, red) larger than the microlens 11 of a color with high sensitivity (for example, green), noise can be reduced for a color with low sensitivity. Thus, the color reproduction area of the solid-state imaging device can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state imaging device having a microlens and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in a solid-state imaging device, since an area not contributing to photoelectric conversion such as a charge transfer section exists in each pixel, the aperture ratio of the light receiving section to the light receiving surface occupying the entire pixel surface is 15 to 30%. However, there is a problem that the utilization rate of incident light is not sufficient. In order to solve such problems and achieve higher sensitivity, the technology of miniaturizing the area other than the light receiving part by the semiconductor process and the high energy ion implantation technology are introduced to increase the saturation charge amount of the transfer register part. Attempts have been made to reduce the area of the transfer register section and increase the area of the light receiving section and the area of the aperture, but these are limited in structure of the solid-state imaging device. Therefore, in recent years, FIG.
As shown in (1), there is provided an image sensor having an on-chip microlens in which a convex microlens is provided above a light receiving unit, and the incident light is efficiently condensed on the light receiving unit to increase the effective aperture ratio.

Further, a color solid-state image sensor has a color filter in addition to a micro lens. A general manufacturing method for forming a color filter and a microlens on an imaging device in which a plurality of light receiving portions for performing photoelectric conversion are formed on a surface layer portion of a substrate is as follows. Fill the hole in the light receiving part with the transparent resin of the light receiving part Flatten the light receiving part Form the color filter Flatten the color filter with the transparent resin Form the micro lens

[0004] In particular, the formation of a microlens will be described with reference to the drawings. FIG. 3 is an explanatory diagram of a conventional method for manufacturing a microlens. 1 is a semiconductor substrate, 2 is a light receiving section, 3 is a charge transfer section, 4 is a lower flattening layer, 5 is a color filter, 6
Denotes a light shielding film, and 7 denotes an upper flattening layer (see FIG. 3A). A microlens resist, which is a microlens material, is applied on the upper planarization layer, and a pattern 12 is formed by a conventional photolithography technique (FIG. 3).
(Refer to FIG. 3B), a heat treatment is performed, and the pattern is deformed to form a convex microlens 13 on the light receiving portion (FIG. 3).
(C)).

In recent years, as the resolution and size of the solid-state imaging device have been increased, it has been necessary to increase the definition of the microlens. At the same time, since the light receiving area of the light receiving section is reduced, it is desirable to increase the width of the lenses while keeping the light condensing position of the microlenses and to minimize the distance between the lenses. That is, it is desirable to minimize the space between the microlenses in FIG.

[0006]

However, due to the limitation of the spectral transmittance of the color filter, that is, the color resolution of the color filter and the photoelectric conversion wavelength dependence of the photoelectric conversion element,
Even if the space between microlenses is simply reduced, there is a color that does not sufficiently satisfy the sensitivity, and there is a problem that the color reproduction area of the solid-state imaging device is narrowed.

Accordingly, an object of the present invention is to provide a solid-state imaging device capable of improving the sensitivity of all colors and improving the color reproduction area.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and the invention according to claim 1 is provided with a plurality of light receiving portions on a semiconductor substrate, and a color filter on the light receiving portion. And a size of a micro lens formed on a color filter of one color is different from a size of a micro lens formed on a color filter of another color in a solid-state imaging device formed with a micro lens. A solid-state image sensor.

According to a second aspect of the present invention, there is provided a solid-state image pickup device based on the first aspect of the present invention, wherein the color filters are constituted by primary color filters, and the filter array has a Bayer system and an interline system. is there.

According to a third aspect of the present invention, there is provided a solid-state imaging device in which the size of a microlens formed on a color filter of one color is different from the size of a microlens formed on a color filter of another color. A method of manufacturing a solid-state imaging device, comprising: forming a microlens on a color filter of one color and then forming a microlens on a color filter of another color.

[0011]

[First Embodiment] Next, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the first embodiment.
4A and 4B are explanatory views of a cross-sectional structure and a planar structure showing a manufacturing process of the solid-state imaging device according to the first embodiment. FIG. 1A is a cross-sectional view of the solid-state imaging device when a color filter is formed on the solid-state imaging device and an upper flattening layer is formed thereafter. 1 is a semiconductor substrate, 2
Is a light receiving portion, 3 is a charge transfer portion, 4 is a lower flattening layer, 5 is a color filter, 6 is a light shielding film, and 7 is an upper flattening layer, which is the same as the conventional structure. Description is omitted.

Next, as shown in FIG. 1B, patterns 8 and 9 of microlens resists having different sizes (widths) are formed in a checkered pattern on the upper flattening layer 7 and heat-treated. Micro lenses 10 and 11 are formed. That is, G
A microlens with a small lens width is placed on the (green / 1 color) color filter, and a microlens with a large lens width is placed on the R (red / other color) and B (blue / other color) color filters. (That is, the sizes of the G, R, and B microlenses are different). The heights of the large micro lens and the small micro lens are substantially the same. As a result, the spectral sensitivities of R (red) and B (blue) with low sensitivity can be improved, and the color reproduction area of the solid-state imaging device can be expanded by aligning the spectral sensitivities of R, G, and B.

[Embodiment 2] A second embodiment of the present invention will be described with reference to the drawings. FIG. 2 is an explanatory diagram of a cross-sectional structure and a planar structure showing a manufacturing process of the solid-state imaging device according to the second embodiment. FIG. 2A is a cross-sectional view of the solid-state imaging device when a color filter is formed on the solid-state imaging device and then an upper flattening layer is formed. 1 is a semiconductor substrate, 2 is a light receiving section,
In the three charge transfer portions, 4 is a lower flattening layer, 5 is a color filter, 6 is a light shielding film, and 7 is an upper flattening layer, which is the same as the conventional configuration. .

The filter arrangement of the color filters is as follows.
From the viewpoint of preventing fusion of the microlenses, it is desirable to have a Bayer system or an interline system in which the same colors are arranged in a checkered pattern.

Next, as shown in FIG. 2B, a pattern 8 is formed on the upper flattening layer 7 on a checkered, ie, R (red), B (blue) color filter by a conventional photolithography technique. Then, a microlens 10 having a large lens width is formed by a heat treatment (see FIG. 2C). afterwards,
As shown in FIG. 2D, a pattern 9 and a microlens 11 having a small lens width are formed on the G (green) color filter in the same manner (see FIG. 2E). According to this manufacturing method, it is also possible to change the height of the large micro lens and the small micro lens by changing the thickness of the pattern. Further, by using a microlens forming resist having a different refractive index, it is possible to change the light condensing rate. As a result, the spectral sensitivities of R (red) and B (blue) with low sensitivity can be further improved, and the color reproduction area of the solid-state imaging device can be expanded.

[0016]

As is clear from the above, according to the solid-state imaging device of the first aspect, the size of the microlens formed on the color filter of one color is formed on the color filter of another color. Since the size of the microlens is different from the size of the microlens, the size of the microlens of low sensitivity (for example, blue and red) is made larger than the microlens of high sensitivity (for example, green), and the spectral sensitivity is increased. By increasing the value, noise can be reduced for a color having low sensitivity, and the color reproduction region of the solid-state imaging device can be improved.

According to the method of manufacturing a solid-state imaging device according to the third aspect, the solid-state imaging device according to the first aspect can be easily manufactured, and the height of the microlens can be increased for each color of the color filter. And the microlens resist can be changed. As a result, low sensitivity R (red),
The spectral sensitivity of B (blue) can be further improved, and the color reproduction area of the solid-state imaging device can be expanded.

[0018]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a cross-sectional structure illustrating a manufacturing process of a solid-state imaging device according to a first embodiment.

FIG. 2 is a cross-sectional view of a cross-sectional structure illustrating a manufacturing process of a solid-state imaging device according to a second embodiment.

FIG. 3 is a cross-sectional view of a cross-sectional structure illustrating a manufacturing process of a conventional solid-state imaging device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Light receiving part 3 Charge transfer part 4 Lower flattening layer 5 Color filter 6 Light shielding layer 7 Upper flattening layer 8 Pattern 9 Pattern 10 Large micro lens 11 Small micro lens 12 Pattern 13 Micro lens

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 9/07 H04N 9/07 A F term (Reference) 2H048 BB02 BB10 BB13 BB46 4M118 AA06 AA10 AB01 BA13 CA27 FA06 GC08 GC14 GD04 GD07 5C024 AA01 CA31 EA04 EA08 FA01 FA11 5C065 AA01 BB42 DD01 EE03 EE11

Claims (3)

[Claims] 1. A solid-state imaging device having a plurality of light receiving portions on a semiconductor substrate and a color filter and a micro lens formed on the light receiving portion, the size of a micro lens formed on a color filter of one color. Is different from the size of a micro lens formed on a color filter of another color. 2. The solid-state imaging device according to claim 1, wherein the filter array of the color filter has a Bayer system or an interline system. 3. A method for manufacturing a solid-state imaging device in which the size of a microlens formed on a color filter of one color is different from the size of a microlens formed on a color filter of another color. A method for manufacturing a solid-state imaging device, comprising: forming a microlens on a color filter of one color, and then forming a microlens on a color filter of another color.