JPH11289073A - Solid image pickup device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure for efficiently introducing a light transmitted through a photographic lens set in front of a solid image pickup device to a photoelectric converting element in a solid image pickup device. SOLUTION: This solid image pickup device is constituted so that the sum of the thickness of color filters 8a, 8b, and 8c and the thickness of a filter thickness adjusting layer 10 can be made equal at the position of each color filter, and a micro-lens 9 is formed on this. Thus, a distance from the micro-lens 9 to a photoelectric converting element 2 can be made short, and the opening area of the photoelectric converting element 2 for the micro-lens 9 can be apparently increased.

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 plurality of two-dimensionally arranged photoelectric conversion elements, and more particularly to a solid-state imaging device in which a light condensing means is formed on a photoelectric conversion element. And a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for a camera having a built-in solid-state image pickup device, such as a camera-integrated video, to have a smaller size and higher performance. For this reason, the solid-state imaging device has been required to have a reduced chip size, an increased number of pixels, and an improved S / N. Particularly, with respect to S / N, an optical lens is formed directly on the photoelectric conversion element in order to increase the input light to the photoelectric conversion element in parallel with improving the sensitivity of the photoelectric conversion element. .

FIG. 7 is a sectional view of a main part of a conventional solid-state imaging device. In FIG. 7, 31 is a silicon substrate, 32 is a photoelectric conversion element, 33 is a first insulating film, 34 is a polycrystalline silicon electrode, 35 is a light-shielding film composed of a metal deposition film, 36 is a protective film, and 37 is a photoelectric film. A flattening layer for flattening the surface of the conversion element, 38a is a color filter dyed red (hereinafter referred to as R filter), 38b is a color filter dyed green (hereinafter referred to as G filter), and 38c is blue. The dyed color filters (hereinafter referred to as B filters) 39a, 39b, and 39c are flattening layers 40 formed to flatten the upper surface of the color filters, respectively.
Is a microlens formed above the photoelectric conversion element 32.

In a solid-state image pickup device, color filters formed corresponding to the photoelectric conversion elements 32 arranged in a matrix are arranged in a row and a column direction by using a combination of an R filter, a G filter, and a B filter as one unit. In general, the R filter, the G filter, and the B filter have different thicknesses to obtain desired spectral characteristics. In order to flatten the upper surface of the color filter, an acrylic resin or the like is applied several times and then hardened to cure the flattened layers 39a and 39a.
b, 39c are formed.

[0005]

In a solid-state imaging device, it is required that light that has passed through a photographing lens installed in front of the solid-state imaging device be efficiently guided to a photoelectric conversion element. However, the solid-state imaging device is provided with a vertical transfer stage, a horizontal transfer stage, and other circuits for transferring electric charges from the photoelectric conversion element in addition to the photoelectric conversion element. Since the ratio of circuits other than the photoelectric conversion elements occupies a large proportion, a considerable amount of light passing through the photographing lens is lost without being incident on the photoelectric conversion elements.

In order to solve this problem, a method of forming a microlens on the front surface of a photoelectric conversion element by extending a semiconductor process has been developed. When a micro lens is formed, the light passing through the photographing lens is collected by the micro lens, so that the amount of light incident on the photoelectric conversion element increases,
Brightness is improved as a photographing system.

According to the present invention, in a solid-state image pickup device having a microlens formed therein, by improving an optical system from the microlens to the photoelectric conversion element, light passing through the photographing lens can be more efficiently guided to the photoelectric conversion element. It is an object to provide a solid-state imaging device.

[0008]

In order to solve this problem, a solid-state imaging device according to the present invention is arranged such that the sum of the thickness of a color filter and the thickness of a filter thickness adjustment layer is equal at the position of each color filter. It is composed. That is, after forming the color filter, a portion of the thin color filter is filled with a filter thickness adjustment layer, or after forming a filter thickness adjustment layer having a thickness to correct the thickness of the color filter in advance, the color is adjusted. By forming the filter, the sum of the thickness of the color filter and the thickness of the filter thickness adjusting layer can be made equal.

As a result, the distance from the microlens provided on the color filter to the photoelectric conversion element is shortened, and the opening area of the photoelectric conversion element with respect to the microlens is apparently increased. The light amount incident on the photoelectric conversion element increases in the portion.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a plurality of photoelectric conversion elements are two-dimensionally arranged on a main surface of a semiconductor substrate, and a flattening layer is formed on the semiconductor substrate. A color filter composed of a plurality of types of color patterns having different thicknesses is formed on the conversion layer, and a filter thickness adjustment layer made of a transparent resin is formed on the color filter excluding the color pattern having the maximum thickness, and the photoelectric conversion element is formed. Correspondingly, a microlens is formed on the color pattern having the maximum thickness and on the filter thickness adjustment layer, and the sum of the thickness of the filter thickness adjustment layer and the thickness of the color filter formed under the filter thickness adjustment layer Has a configuration in which the filter thickness adjustment layer is formed so as to be substantially equal to the thickness of the color pattern having the maximum thickness, and the distance from the microlens to the photoelectric conversion element is reduced. So that the opening area of the photoelectric conversion element is increased to the eye microlenses.

According to a second aspect of the present invention, a plurality of photoelectric conversion elements are two-dimensionally arranged on a main surface of a semiconductor substrate, a flattening layer is formed on the semiconductor substrate, and A filter thickness adjustment layer made of a transparent resin is formed in a part of the region, and a color filter including a plurality of types of color patterns having different thicknesses is formed on the flattening layer and the filter thickness adjustment layer. The color pattern of the maximum thickness is arranged on the activated layer, the micro lens is formed on the color filter corresponding to the photoelectric conversion element, the thickness of the filter thickness adjusting layer and the thickness of the filter thickness adjusting layer are formed. The filter thickness adjustment layer is formed so that the total of the thickness of the color filter and the thickness of the color pattern having the maximum thickness formed on the flattening layer is substantially equal to the thickness of the color pattern. Same as 1 So that the opening area of the photoelectric conversion element with respect to the micro lens increases.

According to a third aspect of the present invention, in the first or second aspect, a reaction between a resin material forming a microlens below the microlens and a resin material forming a color filter is prevented. Claim 1 has a structure in which a reaction prevention layer is formed, and such a reaction prevention layer can be thinned by appropriately selecting a material.
Or, the function and effect of the invention described in claim 2 are not so much hindered.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a solid-state imaging device according to the first aspect, wherein a transparent resin material is formed on a semiconductor substrate on which photoelectric conversion elements are two-dimensionally arranged and formed. Forming a flattening layer for flattening the surface of the semiconductor substrate using the same, forming a color filter comprising a plurality of types of color patterns having different thicknesses on the flattening layer, and forming a color pattern having a maximum thickness. Forming a filter thickness adjustment layer made of a transparent resin on a color filter excluding the step of forming a microlens on the maximum thickness color pattern and the filter thickness adjustment layer corresponding to the photoelectric conversion element So that the sum of the thickness of the filter thickness adjustment layer and the thickness of the color filter formed under the filter thickness adjustment layer is substantially equal to the thickness of the color pattern having the maximum thickness. And forming a filter thickness adjusting layer, resulting in the surface can provide a flat solid-state imaging device.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a solid-state imaging device according to the second aspect, wherein a transparent resin material is formed on a semiconductor substrate on which photoelectric conversion elements are two-dimensionally arranged. Forming a flattening layer for flattening the surface of the semiconductor substrate by using the method, forming a filter thickness adjusting layer in a partial region on the flattening layer, and forming a filter thickness adjusting layer on the flattening layer. Forming a color filter composed of a plurality of types of color patterns having different thicknesses on the top, and arranging a color pattern having a maximum thickness on the flattening layer;
Forming a microlens corresponding to the photoelectric conversion element on the filter, wherein the sum of the thickness of the filter thickness adjustment layer and the thickness of the color filter formed on the filter thickness adjustment layer is flattened. By forming the filter thickness adjustment layer so as to be substantially equal to the thickness of the color pattern having the maximum thickness formed on the layer, it is possible to provide a solid-state imaging device having a flat surface.

(Embodiment 1) FIG. 1 is a sectional view showing a main part of a solid-state imaging device according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes a silicon substrate, 2 denotes a photoelectric conversion element, 3 denotes a first insulating film, 4 denotes a polycrystalline silicon electrode having an oxide film formed on the surface, and 5 denotes a metal-deposited film such as an aluminum-deposited film. 6, a protection film such as a silicon oxide film or a silicon nitride film; 7, a photoelectric conversion element flattening layer for flattening the surface of the photoelectric conversion element using acrylic; 8a, an R filter; A G filter, 8c is a B filter, 10 is a filter thickness adjustment layer, and 9 is a microlens.

In the example shown in FIG. 1, the B filter 8c is the thickest, and the G filter 8b and the R filter 8a are thinner in this order. This is just an example, and the order of the thickness is actually different depending on the dyeing conditions. This embodiment is different from the conventional example shown in FIG.
Is the thickest, no filter thickness adjusting layer is formed on the upper surface thereof, and the filter thickness adjusting layers corresponding to the respective filter thicknesses are formed on the upper surfaces of the R filter 8a and the G filter 8b. The point is that a layer is formed.

With this configuration, the distance between the microlens and the photoelectric conversion element is determined by the thickness of the thickest B filter.

(Embodiment 2) FIG. 2 is a sectional view of a main part of a solid-state imaging device according to Embodiment 2 of the present invention. 2, the same parts as those in the first embodiment shown in FIG. In FIG. 2, 10a is R
The filter thickness adjustment layers 10b are G filter thickness adjustment layers. These filter thickness adjustment layers are formed using an acrylic resin, and the thickness thereof is, for example, the sum of the thickness of the R filter thickness adjustment layer 10a and the thickness of the R filter 8a being equal to the thickness of the B filter 8c. Adjusted to be equal to
The G filter thickness adjustment layer 8b is similarly adjusted.

The solid-state imaging device according to the second embodiment differs from the first embodiment shown in FIG. 1 in that a filter thickness adjustment layer is provided below the filter. Also in this case, similarly to the first embodiment, the distance between the microlens and the photoelectric conversion element is determined by the total thickness of the thickest B filter and the thickness of the photoelectric conversion element flattening layer. By providing the filter thickness adjustment layer below the filter, the curing temperature of the acrylic resin used for the filter thickness adjustment layer can be determined without considering the effect on the filter. Thus, a more completely cured filter thickness adjusting layer can be obtained.

(Embodiment 3) FIGS. 3 (a) to 3 (c) are cross-sectional views illustrating the first half of the method of manufacturing the solid-state imaging device according to Embodiment 1 shown in FIG. 1, and FIGS. (D)
FIG. 7 is a process cross-sectional view for explaining the latter half of the manufacturing method.
First, as shown in FIG. 3A, on a silicon substrate 1, a photoelectric conversion element 2, a first insulating film 3, a polycrystalline silicon electrode 4 whose surface is oxidized, a light shielding film 5, a protective film 6, and other components. Form a circuit part. Next, as shown in FIG. 3B, an acrylic resin is applied to fill the irregularities on the surface of the silicon substrate 1 and cured to form a flattening layer 7 on the entire surface of the silicon substrate 1.

Next, as shown in FIG. 3C, an R filter 8a, a G filter 8b, and a B filter 8c are sequentially formed. These color filters are formed by a usual dyeing method or a method of applying a filter material mixed with a pigment. In FIG. 3, the R filter 8a is shown as the thinnest, but this is shown only as an example, and the R filter 8a is actually
The thickness of each of the filters 8a, 8b, and 8c is determined in consideration of the respective optical spectral characteristics.

Next, as shown in FIG. 3D, an acrylic resin is applied to the entire surface so that the surface of the thickest filter is exposed, and is cured to form a filter thickness adjusting layer 10.

Next, as shown in FIG. 4A, a photosensitive resin 11 for forming a microlens is applied to the entire surface. Next, as shown in FIG. 4B, a resin pattern 12 is formed by mask exposure and development. Next, as shown in FIG. 4 (c), the acrylic resin pattern 12 is heated at a softening temperature and softened and flowed to form the microlenses 9 by surface tension. Thereafter, the resin constituting the microlens 9 is cured at a temperature higher than the softening temperature.

The subsequent steps are the same as in the case of the conventional solid-state imaging device with microlenses. (Embodiment 4) FIGS. 5A to 5D are process sectional views illustrating a method for manufacturing a solid-state imaging device according to Embodiment 2 shown in FIG. Note that the present embodiment is different from the third embodiment in that a filter thickness adjustment layer is formed before forming a color filter, and only different points will be described.

First, FIGS. 5A and 5B are the same as FIGS. 3A and 3B in the third embodiment. Next, as shown in FIG. 5C, filter thickness adjusting layers 21a and 21b are sequentially formed using acrylic resin as a material. At this time, the thickness of the filter thickness adjustment layer is determined in consideration of the thickness of the color filter formed in a later step.

Next, as shown in FIG. 5D, the R filter 22a is formed on the filter thickness adjusting layer 21a, the G filter 22b is formed on the filter thickness adjusting layer 21b, and the filter thickness adjusting layer is formed. The B filter 22c having the largest thickness is formed in a region where it is not formed. These color filters are formed by a usual dyeing method or a method of applying a filter material mixed with a pigment. In FIG. 3, the R filter 8a is shown as the thinnest, but this is shown only as an example, and the R filter 8a and the G filter 8 are actually shown.
The individual thicknesses are determined in consideration of the respective optical spectral characteristics of the b and B filters 8c. In the fourth embodiment,
The color filters are all exposed on the surface, and if necessary, an extremely thin protective layer may be formed on the surface before forming the microlenses.

The steps after the step of forming the microlenses are almost the same as those shown in FIGS. 4A to 4C, and the description is omitted.

The solid-state imaging device according to the present invention described above has a feature that the distance from the microlens to the photoelectric conversion element is shorter than that of the conventional solid-state imaging device.
FIGS. 6A and 6B are conceptual cross-sectional views illustrating an optical system of a solid-state imaging device according to an embodiment of the present invention. The relationship between the distance up to and the apparent light sensitivity will be described. FIG. 6A shows one photoelectric conversion element located at the center of the solid-state imaging device, and FIG. 6B shows one photoelectric conversion element located at the periphery of the solid-state imaging device. . In these figures, 2a is the photoelectric conversion element of the present invention, 2b
Indicates the position of the conventional photoelectric conversion element.
Is a micro lens. Reference numerals 32 and 33 denote incident light beams incident on the photoelectric conversion element, respectively, 32 denotes an incident light beam when the taking lens is stopped down, and 33 denotes an incident light beam when the stop is almost open. Although not shown, the taking lens is a lens used when a camera is configured using a solid-state imaging device, and forms an optical system of the camera together with the diaphragm. in this way,
The incident light beam 32 when the aperture of the taking lens is narrowed is incident on both of the photoelectric conversion elements 2a and 2b, and there is no difference between this and the present invention. However, when the aperture of the taking lens is opened, the incident light beam becomes like 33. In this case, the difference 34 between the incident light beam 32 and the incident light beam 33 becomes invalid light at the position of the conventional photoelectric conversion element 2b, but becomes sufficiently effective light at the position of the photoelectric conversion element 2a of the present invention.

In the peripheral portion of the solid-state imaging device shown in FIG. 6B, all incident light rays enter the microlens 9 from an oblique direction. The incident light between the incident light 35b and the incident light 35c can be received by both the present invention and the conventional photoelectric conversion element 2a, 2b, but the incident light 36 between the incident light 35a and the incident light 35b is the present invention. Is incident on the position of the photoelectric conversion element 2a, but does not enter the position of the conventional photoelectric conversion element 2b, and becomes invalid light.

Therefore, in the solid-state imaging device according to the present invention, the incident light beam, which was conventionally invalid light, also enters the photoelectric conversion element, and the apparent sensitivity is improved by that amount.

[0031]

As described above, according to the present invention, the distance between the microlens and the photoelectric conversion element can be reduced as compared with the conventional solid-state imaging device, and the amount of light incident on the photoelectric conversion element can be increased. Is obtained. The effect when the distance between the microlens and the photoelectric conversion element is shortened is particularly when the oblique light component is large, such as when the aperture of the imaging lens is opened (the F value is small) under the low illumination condition. Or, it is particularly remarkable in the periphery of the solid-state imaging device when the exit pupil distance is short, such as in a micro camera lens, and the difference in apparent sensitivity between the central and peripheral photoelectric conversion elements is reduced.

[Brief description of the drawings]

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

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

FIG. 3 is a process cross-sectional view for explaining the first half of the method of manufacturing the solid-state imaging device according to Embodiment 1 of the present invention;

FIG. 4 is a process cross-sectional view for explaining the latter half of the method of manufacturing the solid-state imaging device according to Embodiment 1 of the present invention;

FIG. 5 is a process sectional view for illustrating the method for manufacturing the solid-state imaging device according to Embodiment 2 of the present invention.

FIGS. 6A and 6B are diagrams illustrating an optical system of a solid-state imaging device according to an embodiment of the present invention;

FIG. 7 is a sectional view of a main part of a conventional solid-state imaging device.

[Explanation of symbols]

 Reference Signs List 2 photoelectric conversion element 7 flattening layer 8a color filter (R filter) 8b color filter (G filter) 8c color filter (B filter) 9 microlens 10 filter thickness adjustment layer

Claims (5)

[Claims] 1. A plurality of photoelectric conversion elements are two-dimensionally arranged on a main surface of a semiconductor substrate, a flattening layer is formed on the semiconductor substrate, and a plurality of types of colors having different thicknesses are formed on the flattening layer. A color filter made of a pattern is formed, and a filter thickness adjustment layer made of a transparent resin is formed on the color filter excluding the color pattern having the maximum thickness, and the color pattern having the maximum thickness corresponding to the photoelectric conversion element is formed. A solid-state imaging device having a microlens formed thereon and on the filter thickness adjustment layer, wherein a total of a thickness of the filter thickness adjustment layer and a thickness of a color filter formed under the filter thickness adjustment layer is provided. Wherein the filter thickness adjusting layer is formed so that the thickness of the color pattern is substantially equal to the thickness of the color pattern having the maximum thickness. 2. A plurality of photoelectric conversion elements are two-dimensionally arranged on a main surface of a semiconductor substrate, a flattening layer is formed on the semiconductor substrate, and a partial region on the flattening layer is made of a transparent resin. A filter thickness adjustment layer is formed, and a color filter including a plurality of types of color patterns having different thicknesses is formed on the flattening layer and the filter thickness adjustment layer,
A solid-state imaging device in which a color pattern having a maximum thickness is disposed on the flattening layer, and a microlens is formed on the color filter in correspondence with the photoelectric conversion element; The filter so that the sum of the thickness of the layer and the thickness of the color filter formed on the filter thickness adjustment layer is substantially equal to the thickness of the color pattern having the maximum thickness formed on the planarization layer. A solid-state imaging device comprising a thickness adjustment layer. 3. A reaction preventing layer for preventing a reaction between a resin material forming the microlens and a resin material forming a color filter is formed under the microlens. 3. The solid-state imaging device according to 2. 4. A step of forming a flattening layer for flattening the surface of a semiconductor substrate using a transparent resin material on a semiconductor substrate on which photoelectric conversion elements are formed two-dimensionally, and forming a flattening layer on the flattening layer. Forming a color filter composed of a plurality of types of color patterns having different thicknesses; forming a filter thickness adjustment layer made of a transparent resin on the color filter excluding the color pattern having a maximum thickness; Forming a microlens on the color pattern having the maximum thickness and the filter thickness adjustment layer corresponding to the element, wherein the thickness of the filter thickness adjustment layer and the thickness of the filter thickness adjustment layer The filter thickness adjustment layer is formed such that the sum of the thickness of the color filter formed under the filter thickness adjustment layer and the thickness of the color pattern having the maximum thickness is substantially equal to the thickness of the color pattern. And a step of manufacturing the solid-state imaging device. 5. A step of forming a flattening layer for flattening the surface of a semiconductor substrate using a transparent resin material on a semiconductor substrate on which photoelectric conversion elements are two-dimensionally arranged and formed; Forming a filter thickness adjustment layer in the region of the portion, and forming a color filter comprising a plurality of types of color patterns of different thicknesses on the flattening layer and the filter thickness adjustment layer, and A step of arranging a color pattern having a maximum thickness on a passivation layer, and a step of forming a microlens corresponding to the photoelectric conversion element on the filter, the method comprising: The sum of the thickness of the thickness adjustment layer and the thickness of the color filter formed on the filter thickness adjustment layer is substantially equal to the thickness of the color pattern having the maximum thickness formed on the flattening layer. A method for manufacturing a solid-state imaging device, comprising forming the filter thickness adjustment layer.