JP2002280532A - Solid-state imaging device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the photosensitivity of a photoelectric conversion unit and suppress a smear phenomenon in which bleeding occurs due to leakage of signal charges from unselected pixels. SOLUTION: A plurality of photoelectric conversion units 2 as light receiving units are provided at regular intervals inside a semiconductor substrate 1,
Charge transfer electrodes 4 for transferring signal charges respectively generated by the photoelectric conversion units 2 on the semiconductor substrate 1 are provided between the photoelectric conversion units 2, respectively.
An insulating film 6 is stacked on the insulating film 6 so as to bury each charge transfer electrode 4, and a pixel separating film 7 is provided on the insulating film 6 at a position facing the photoelectric conversion unit 2. A V-shaped cross section 8 having a predetermined angle is formed between the side surfaces of the pixel separation film 7.

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, and more particularly, to a solid-state imaging device in which a photoelectric conversion unit as a light receiving unit has improved light-collecting efficiency.

[0002]

2. Description of the Related Art In recent years, solid-state imaging devices have become available in the market.
From the viewpoint of convenience and the like, a reduction in the size of the shape and an increase in the number of pixels in the image are required. As a result, the occupied area inside the solid-state imaging device of the unit cell including the photoelectric conversion unit, which is the light receiving unit of the solid-state imaging device, and the charge transfer unit is reduced. The reduction in the area of the photoelectric conversion unit accompanying the reduction in the area occupied by the unit cell reduces the rate of condensing incident light on the photoelectric conversion unit, which is one of the main characteristics of the solid-state imaging device. May decrease the light sensitivity of

Conventionally, in response to such a decrease in light sensitivity of the photoelectric conversion unit, a micro-beam is placed on the optical path of incident light on the upper part of the photoelectric conversion unit so as to face the photoelectric conversion unit which is the light receiving unit of the solid-state imaging device. A lens is formed, and incident light is efficiently condensed on the photoelectric conversion unit to improve the light sensitivity of the photoelectric conversion unit.

FIG. 5 is a schematic cross-sectional view of a conventional solid-state imaging device in which the microlens for condensing incident light on the photoelectric conversion unit is used to improve the light collection rate of the photoelectric conversion unit. is there. In the solid-state imaging device shown in FIG. 5, a plurality of photoelectric conversion units 2 are embedded at regular intervals above a semiconductor substrate 1. A charge transfer unit (transfer register: not shown) is provided between the adjacent photoelectric conversion units 2, and a charge readout unit (transfer gate: transfer gate: charge transfer unit) is provided so as to cover all the photoelectric conversion units 2 and the charge transfer units. (Not shown) and an interlayer film 3 are formed. On the interlayer film 3, a plurality of charge transfer electrodes 4 each having a rectangular cross section are formed between the adjacent photoelectric conversion units 2 at regular intervals. The surface of each charge transfer electrode 4 Are covered with light-shielding films 5 defining the photosensitive regions.

[0005] On the interlayer film 3, an insulating film 6 is laminated so as to bury the charge transfer electrode 4 covered with the light shielding film 5. On the insulating film 6, a color filter 19 and a transparent flattening film 20 for flattening the surface of the color filter 19 are sequentially laminated. Flattening film 20
On the upper side, a plurality of microlenses 15 for condensing incident light on the respective photoelectric conversion units 2 are formed at regular intervals for each pixel. The microlens 15 is provided at a position facing the photoelectric conversion unit 2 as a light receiving unit so as to be extended beyond the area (width) of the photoelectric conversion unit 2. Each micro lens 15 is a convex lens having a central part thicker than a peripheral part.

As shown in FIG. 5, incident light incident on the microlens 15 from the outside (arrows 13, 16 and 1 in FIG. 5).
7 and 18) are refracted on the surface of the microlens 15 and proceed toward the photoelectric conversion unit 2, and pass through the flattening film 20, the color filter 19, the insulating film 6, and the interlayer film 3 to form the photoelectric conversion unit 2. The light is irradiated onto the light receiving surface, and the photoelectric conversion unit 2 excites signal charges. Incident light (arrows 13, 16, 17, 1 in FIG. 5)
8) is read out by a charge reading section (transfer gate: not shown) formed below the charge transfer electrode 4, and is transferred to a charge transfer section (transfer register: not shown). ). The light-shielding film 5 covering the charge transfer electrode 4 is a charge readout section (transfer gate: not shown).
And a function of reducing the amount of light incident on a charge transfer unit (transfer register: not shown).

[0007] Since the microlens 15 is larger than the width of the photoelectric conversion unit 2, the incident light 13 incident from the outside on the periphery of the microlens 15 is such that the incident position of the incident light 13 is the photoelectric conversion unit. Despite being out of the region (width) 2, the light is focused on the photoelectric conversion unit 2 by the microlens 15.

As described above, by providing the microlens 15 at a position facing the photoelectric conversion unit 2, the signal charge excited in the photoelectric conversion unit 2 increases, and
Significant effects such as a reduction in incident light incident on the light-shielding film 5, an improvement in the optical sensitivity of the photoelectric conversion unit 2, and a suppression of a smear phenomenon that causes bleeding due to leakage of signal charges from unselected pixels can be obtained. . Therefore, if the bottom surface of the microlens 15 provided on the flattening film 20 is increased and the region where the microlens 15 is not present is further reduced so that external incident light is incident on the surface of the microlens 15, The incident light indicated by arrows 11 and 12 in FIG. 5 is also collected on the photoelectric conversion unit 2, so that the amount of light collected on the photoelectric conversion unit 2 increases, and the light sensitivity of the photoelectric conversion unit 2 is improved.
Further, the suppression of the smear phenomenon caused by the leakage of the signal charge from the unselected pixels can be further improved.

In this specification, for the sake of simplicity, the refractive indices of the microlens 15, the flattening film 20, the color filter 19, and the insulating film 6 are all the same for the sake of simplicity. The microlens 15 is usually made of a material having a refractive index of about 1.6.

However, on the flattening film 20,
When the bottom surface of the microlens 15 is enlarged and the region where the microlens 15 is not present is reduced, for example, a plurality of adjacent microlenses 15 on the flattening film 20 come into contact with each other, and the contact portion of the microlens 15 becomes a pixel defect. The image quality may be significantly degraded. In addition, due to processing variations at the time of forming the microlenses 15, a part of the incident light projected from the outside onto the microlenses 15 of the solid-state imaging device passes through the color filter 19 facing the adjacent photoelectric conversion unit 2, and an image is formed. Color mixing may occur. Therefore, it is not easy to increase the bottom surface of the microlens 15 and reduce the area where the microlens 15 does not exist on the flattening film 20.

For this reason, the incident light (FIG. 5) incident on the region on the flattening film 20 where the microlens 15 does not exist.
Are indicated by arrows 11 and 12) in the photoelectric conversion unit 2 as a light receiving unit.
6 and 7, a solid-state imaging device in which a concave lens having an action of diffusing incident light from the outside is formed in a region where the microlens 15 does not exist on the flattening film 20 as shown in FIGS. Are described in JP-A-5-27196, JP-A-9-45884, and JP-A-11-876.
No. 73, for example.

In the solid-state imaging device shown in FIG. 6, microlenses 15 for condensing incident light on the photoelectric conversion unit 2 are formed at regular intervals on the insulating film 6 for each pixel. On the insulating film 6, a concave concave lens 21 is provided at a position facing the charge transfer electrode 4 where the microlens 15 is not formed.
Are formed respectively. The micro lens 15 and the concave lens 21 are formed alternately and continuously on the surface of the insulating film 6. Other configurations are the same as those of the solid-state imaging device shown in FIG.

As described above, in the solid-state imaging device shown in FIG. 6, the microlens 15 and the concave lens 21 are provided adjacent to each other on the surface of the insulating film 6, and the incident light (FIG. Arrows 13, 16, 1 to 6
7 and 18) are refracted on the surface of the microlens 15 and proceed toward the photoelectric conversion unit 2, and the microlens 1
Irradiation is performed on the light receiving surface of the photoelectric conversion unit 2 through the inside of the element 5, the insulating film 6, and the interlayer film 3. In addition, incident light (indicated by an arrow 12 in FIG. 6) incident on the concave lens 21 in the vicinity of the bottom surface of the microlens 15 is refracted by the concave lens 21 and proceeds toward the photoelectric conversion unit 2, and the insulating film 6, the interlayer film The light is irradiated to the light receiving surface of the photoelectric conversion unit 2 through the light receiving surface 3.

However, the incident light (see the arrow 11 in FIG. 6) incident near the center of the concave lens 21 is refracted by the concave lens 21 and proceeds in the insulating film 6 toward the photoelectric conversion unit 2. The optical path is interrupted by the light-shielding film 5 covering the transfer electrode 4 and cannot reach the light receiving surface of the photoelectric conversion unit 2. In order to make incident light (see arrow 11 in FIG. 6) incident near the center of the concave lens 21 reach the light receiving surface of the photoelectric conversion unit 2, a light-shielding film must be provided on the optical path of the incident light (see arrow 11 in FIG. 6). It is necessary to increase the thickness of the insulating film 6 so that the insulating film 5 does not exist.

In the solid-state imaging device shown in FIG. 7, charge transfer electrodes 4 covered with a light-shielding film 5 are formed at regular intervals on an interlayer film 3, and the first charge transfer electrodes 4 are buried in the charge transfer electrodes 4. Are laminated. On the surface of the first intermediate film 22, concave lenses 23 are formed at regular intervals in the center of a region facing the charge transfer electrode 4 covered with the light shielding film 5. On the first intermediate film 22, a second intermediate film 24 having a smaller refractive index than the first intermediate film 22 is laminated. On the second intermediate film 24, a plurality of microlenses 15 for condensing incident light on the photoelectric conversion unit 2 are formed at regular intervals for each pixel. The interval between the microlenses 15 formed on the second intermediate film 24 corresponds to the width of the concave lens 23 formed on the first intermediate film 22. Other configurations are shown in FIG.
Has the same structure as the solid-state imaging device shown in FIG.

The solid-state imaging device shown in FIG.
Since the concave lens 23 is provided between the second intermediate film 24 and the second intermediate film 24, incident light (indicated by arrows 13, 16, 17, and 18 in FIG. 7) incident on the micro lens 15 from the outside.
Is refracted by the microlens 15 and proceeds toward the photoelectric conversion unit 2, and the second intermediate film 24, the first intermediate film 22,
The light is irradiated on the light receiving surface of the photoelectric conversion unit 2 through the interlayer film 3. Further, the light incident on the region where the microlens 15 is not formed reaches the concave lens 23 formed on the first intermediate film 22 via the second intermediate film 24. In this case, the incident light (arrow 12 in FIG. 7) incident on the peripheral edge of the concave lens 23 is used.
) Is refracted on the surface of the concave lens 23, proceeds toward the photoelectric conversion unit 2, and irradiates the light receiving surface of the photoelectric conversion unit 2 through the first intermediate film 22 and the interlayer film 3. However,
The incident light (see the arrow 11 in FIG. 7) incident near the center of the concave lens 23 is reflected on the surface of the concave lens 23 by the photoelectric conversion unit 2.
Refracted toward the inside of the first intermediate film 22,
The light path is blocked by the light-shielding film 5 covering the charge transfer electrode 4 and cannot reach the light receiving surface of the photoelectric conversion unit 2.
As a result, similarly to the solid-state imaging device shown in FIG. 6, the incident light (see the arrow 11 in FIG. 7) incident near the center of the concave lens 23 It is necessary to increase the thickness of the first intermediate film 22 so that the light shielding film 5 does not exist on the optical path of the arrow 11 in FIG. 7).

[0017]

The microlens 15, which is a main part of the light collecting characteristics of the incident light in the photoelectric conversion unit 2 of the solid-state imaging device, includes the microlens 15 and the photoelectric conversion unit 2.
There is an optimal value for the distance between to avoid pixel defects. For this reason, when the thickness of the insulating film 6 is increased as in the solid-state imaging device of FIG. 6 or the thickness of the first intermediate film 22 is increased as in the solid-state imaging device of FIG.
Since the attenuation of the incident light decreases the light collection rate of the incident light in the photoelectric conversion unit 2, smearing occurs due to a decrease in the optical sensitivity of the photoelectric conversion unit 2 and leakage of signal charges from unselected pixels. The phenomenon may be accelerated.

An object of the present invention is to solve such a problem, and an object of the present invention is to improve the photosensitivity of a photoelectric conversion unit, which is a light receiving unit, and to prevent signal charges from leaking from unselected pixels. An object of the present invention is to provide a solid-state imaging device that suppresses a smear phenomenon that occurs.

[0019]

According to the solid-state imaging device of the present invention, a plurality of photoelectric conversion units as light receiving units are provided at regular intervals inside a semiconductor substrate. Charge transfer electrodes for transferring signal charges respectively generated in the photoelectric conversion units are provided between the photoelectric conversion units, and an insulating film is laminated on the semiconductor substrate so as to embed the charge transfer electrodes. A solid-state imaging device, wherein a pixel separation film is provided at a position on the insulating film facing the photoelectric conversion unit, and a predetermined angle is formed between side surfaces of a pair of adjacent pixel separation films. A groove having a V-shaped cross section is formed.

Each of the pixel separation films is covered with a transparent film, and a transparent film is provided in each of the grooves.

The refractive index of the transparent film is lower than the refractive index of the pixel separation film.

The surface of the transparent film provided in each of the grooves has a concave shape.

The transparent film provided in each of the grooves has a V-shaped cross section.

A convex lens-shaped microlens is provided on each of the pixel separation films.

The periphery of the bottom surface of each of the micro lenses is disposed on the transparent film.

The pixel separation film is a color filter.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of a main part of a solid-state imaging device according to a first embodiment of the present invention. In the solid-state imaging device according to the first embodiment, a plurality of photoelectric conversion units 2 are embedded at regular intervals above a semiconductor substrate 1. A charge transfer unit (transfer register: not shown) is provided between the adjacent photoelectric conversion units 2, and all the photoelectric conversion units 2 are provided.
A charge reading section (transfer gate: not shown) and an interlayer film 3 are formed so as to cover the charge transfer section.
On the interlayer film 3, a plurality of charge transfer electrodes 4 are formed between the adjacent photoelectric conversion units 2 at regular intervals, respectively.
The surface of each charge transfer electrode 4 is covered with a light-shielding film 5 that defines a photosensitive area of incident light. Interlayer film 3
An insulating film 6 is laminated thereon so as to bury the charge transfer electrode 4 covered with the light shielding film 5.

On the insulating film 6, a pixel separation film 7 is formed for each pixel so as to face each photoelectric conversion unit 2 as a light receiving unit. Each pixel separation film 7 has a flat truncated quadrangular pyramid whose upper surface has a gradually decreasing cross-sectional area as it goes upward, and its bottom surface is wider than the region (width) of the photoelectric conversion unit 2. A groove 8 having a V-shaped cross section is formed between a pair of adjacent pixel separation films 7 by mutually facing inclined side surfaces of each pixel separation film 7. On all of the pixel separation films 7, a transparent film 9 having a lower refractive index than each of the pixel separation films 7 is laminated. Then, the surface of the transparent film 9 located on each groove 8 formed between the adjacent pixel separation films 7 is depressed in a concave shape, and the concave lenses 10 are respectively formed.

In the solid-state imaging device shown in FIG. 1, a photosensitive transparent resin having a refractive index n1 ≒ 1.6 (eg, FVR manufactured by Fuji Pharmaceutical Co., Ltd.) is used as the pixel separation film 7.
This photosensitive transparent resin is applied on the insulating film 6 in a range of 0.5 μm to 1.
It is applied with a film thickness of 0 μm, and a pattern of the pixel isolation film 7 having a truncated quadrangular pyramid shape is formed by photolithography. The pixel separation films 7 each having a truncated quadrangular pyramid shape
Although a pattern is formed for each arbitrary unit cell including the photoelectric conversion unit 2 and the charge transfer unit (not shown), one unit cell is formed so that the pattern of each pixel separation film 7 for an adjacent unit cell is not formed at the same time. The pattern formation of each pixel separation film 7 is performed a plurality of times.
At this time, the inclination angle of the side surface of each pixel separation film 7 is changed in the range of 40 ° to 80 ° with respect to the horizontal direction based on the light irradiation amount from the light source and the focal point of the irradiation light, and a pair of adjacent pixels A groove 8 having a V-shaped cross section is formed by mutually facing side surfaces of the separation film 7. In this way, the truncated quadrangular pyramid-shaped pixel separation films 7 are formed at positions facing all the photoelectric conversion units 2 respectively.

Further, a transparent resin 9 having a refractive index n2 膜 1.35, which has a lower refractive index than the pixel separation film 7 (for example, Cyclic Top) is used. This fluorine-based resin is spin-coated on the pixel separation film 7 to a thickness of 0.2 μm to 0.5 μm, and a concave concave lens 10 is formed on the groove 8.
Is formed. Note that the concave shape of the concave lens 10 is adjusted by the viscosity of the fluorine-based resin, the number of revolutions of spin coating, and the like.

With this configuration, the incident light that enters the upper surface of the pixel separation film 7 from the surface of the concave lens 10 passes through the pixel separation film 7, the insulating film 6, and the interlayer film 3 and irradiates the light receiving surface of the photoelectric conversion unit 2. Is done. Further, the incident light (indicated by an arrow 11 in FIG. 1) incident on the vicinity of the central portion of the concave lens 10 formed on the transparent film 9 covering the groove 8 and the incident light (the arrow in FIG. 11 (indicated by arrows 12 and 13 in FIG. 1).
Is refracted on the surface of the concave lens 10 and proceeds in the transparent film 9, and further refracted toward the photoelectric conversion unit 2 by the side surface of the pixel separation film 7. Then, the light reaches the light receiving surface of the photoelectric conversion unit 2 through the inside of the pixel separation film 7, the insulating film 6, and the interlayer film 3, and the signal charge is excited in the photoelectric conversion unit 2.

Therefore, in the solid-state imaging device shown in FIG. 1, most of the surface of the transparent film 9 between the concave lenses 10 and the incident light incident on the concave lenses 10 irradiate the light receiving surface of the photoelectric conversion unit 2, and the photoelectric conversion is performed. The light sensitivity of the unit 2 can be improved.

FIG. 2 is a schematic sectional view of a main part of a solid-state imaging device according to a second embodiment of the present invention. In the solid-state imaging device according to the second embodiment, a groove 14 having a V-shaped cross section similar to the inclined side surface of each pixel separation film 7 is provided in the groove 8 of the transparent film 9 formed on the pixel separation film 7. Have been. The transparent film 9 provided on the pixel separation film 7 has a lower refractive index than the pixel separation film 7. Other configurations are the same as those of the solid-state imaging device according to the first embodiment shown in FIG.

The transparent film 9 has a refractive index n2 ≒ 1.45.
Of silicon oxide film is used. This silicon oxide film is formed on the pixel isolation film 7 by plasma CVD (deposition temperature: 2).
(At 50 ° C.) to a thickness of 0.2 μm to 0.5 μm.

In the solid-state imaging device having such a configuration, incident light (indicated by an arrow 11 in FIG. 2) which is incident near the center of the groove 14 having a V-shaped cross section formed on the transparent film 9 and
The incident light (indicated by arrows 12 and 13 in FIG. 2) incident on the groove 14 above the incident light (indicated by arrow 11 in FIG. 2) is refracted on the surface of the groove 14 and in the transparent film 9. Then, the light is further refracted toward the photoelectric conversion unit 2 by the side surface of the pixel separation film 7. Then, the light reaches the light receiving surface of the photoelectric conversion unit 2 through the inside of the pixel separation film 7, the insulating film 6, and the interlayer film 3, and the signal charge is excited in the photoelectric conversion unit 2.

Therefore, in the solid-state imaging device shown in FIG. 2, most of the light incident on the surface between the grooves 14 of the transparent film 9 and the light incident on the grooves 14 irradiates the light receiving surface of the photoelectric conversion unit 2, The light sensitivity of the unit 2 can be improved.

In the structure of the solid-state imaging device according to the second embodiment, the inclined surface forming the groove 14 formed in the transparent film 9 and the inclined surface of each pixel separation film 7 forming the groove 8 are constant. , The incident light can be refracted in the direction of the photoelectric conversion unit 2 on the inclined surface of the groove 14 and the inclined surface of the pixel separation film 7 without diffusing the incident light. Therefore, in the solid-state imaging device according to the second embodiment, the transparent film 9
The incident light that has entered the upper region of the groove portion 14 adjacent to the flat surface of the above-mentioned portion surely reaches the photoelectric conversion portion 2 via the inside of the transparent film 9, the inside of the pixel separation film 7, the insulating film 6, and the interlayer film 3. There is no possibility that the light will be irradiated and reach the adjacent light shielding film 5. As a result, the light collection rate on the light receiving surface of the photoelectric conversion unit 2 is further improved.

FIG. 3 is a schematic sectional view of a main part of a solid-state imaging device according to a third embodiment of the present invention. In the solid-state imaging device according to the third embodiment, the microlens 15 is formed on the flat upper surface of the truncated square pyramid-shaped pixel separation film 7, and the microlens 15 and the pixel separation film 7 are covered with the transparent film 9. I have. Then, concave lenses 10 are respectively formed in portions of the transparent film 9 located between the adjacent pixel separation films 7. Other configurations are the same as those of the solid-state imaging device according to the first embodiment shown in FIG.

In the solid-state imaging device shown in FIG. 3, a thermosetting photosensitive resin (for example, PMR manufactured by Fuji Pharmaceutical Co., Ltd.) having a refractive index n3 ≒ 1.6 is used for the microlens 15. This thermosetting photosensitive resin is spin-coated at a thickness of 0.5 μm to 1.0 μm on a flat portion of the pixel separation film 7, and after forming a pattern by photolithography, heating at about 150 ° C. As a result, a micro lens 15 having a thickness of about 0.7 μm to 1.5 μm at the center is formed. After the microlens 15 is formed, the transparent film 9 having a lower refractive index than the pixel separation film 7 is formed on the side surface of each pixel separation film 7 based on the procedure described in the solid-state imaging device of the first embodiment. By laminating so as to cover each microlens 15,
As shown in FIG. 3, a concave lens 10 having a concave surface is formed in the groove 8 between the pixel separation films 7.

In the solid-state imaging device having such a configuration, incident light (indicated by arrows 16, 17, and 18 in FIG. 3) passing through the transparent film 9 and entering the microlens 15 is condensed by the microlens 15. As a result, the light is irradiated onto the light receiving surface of the photoelectric conversion unit 2 through the pixel separation film 7, the insulating film 6, and the interlayer film 3 without fail. The incident light (indicated by arrow 1 in FIG. 3) incident on the surface of the transparent film 9 near the center of the concave lens 10 (or V-shaped surface).
1), and incident light (indicated by arrows 12 and 13 in FIG. 3) incident on the concave lens 10 on the peripheral side with respect to the incident light (indicated by arrow 11 in FIG. 3). The light is refracted on the surface and proceeds in the transparent film 9, and further refracted toward the photoelectric conversion unit 2 by the side surface of the pixel separation film 7. Then, the light reaches the light receiving surface of the photoelectric conversion unit 2 through the inside of the pixel separation film 7, the insulating film 6, and the interlayer film 3, and the photoelectric conversion unit 2 excites signal charges.

Therefore, in the solid-state imaging device shown in FIG. 3, most of the surface of the transparent film 9 between the concave lenses 10 and the incident light incident on the concave lenses 10 irradiate the light receiving surface of the photoelectric conversion unit 2, and the photoelectric conversion is performed. The light sensitivity of the unit 2 can be improved.

Since the refractive index n2 of the transparent film 9 is smaller than the refractive index n3 of the microlens 15 (n2 <n3), the transparent film 9 also has a function as an antireflection film for the microlens 15. The reflection of incident light on the surface of the microlens of the conventional solid-state imaging device is reduced by the transparent film 9.

FIG. 4 is a schematic sectional view of a main part of a solid-state imaging device according to a fourth embodiment of the present invention. In the solid-state imaging device according to the fourth embodiment, the bottom surface of the microlens 15 formed in each pixel separation film 7 is wider than the top surface of the pixel separation film 7, and the periphery thereof is located around the top surface of the pixel separation film 7. Are located. The transparent films 9 are provided only in the adjacent grooves 8, and the concave lenses 10 (or V-shaped surfaces) are formed in the respective transparent films 9. The upper end surfaces on both sides of each transparent film 9 are respectively covered with the bottom surface of the microlens 15. Other configurations are the same as those of the solid-state imaging device shown in FIG.

In the solid-state imaging device shown in FIG. 4, a truncated quadrangular pyramid-shaped pixel separation film 7 having inclined side surfaces is laminated on an insulating film 6, and has a refractive index higher than that of the pixel separation film 7 on the pixel separation film 7. The low transparent film 9 is similarly laminated based on the procedure described in the solid-state imaging device according to the first embodiment, and then the transparent film 9 laminated on the flat upper surface of the pixel separation film 7 is removed. As a method of removing the transparent film 9 laminated on the upper surface of the pixel separation film 7, for example, when the transparent film 9 has the concave lens 10, an etch back by plasma which is a method of flattening the film surface is used. In this method, the thickness of the transparent film 9 provided in the solid-state imaging device according to the first embodiment can be made thinner, so that a concave lens 10 having a large surface area can be formed.

Further, as another method of removing the transparent film 9 laminated on the upper surface of the pixel separation film 7, a pattern is formed by photoresist on the concave lens 10 (or V-shaped surface) on the surface of the transparent film 9; Only the transparent film 9 on the upper surface of the pixel separation film 7 is dry-etched.
The photoresist on the (or V-shaped) is removed. In this method, the shape of the concave lens 10 on the surface of the transparent film 9 is
Concave lens 1 provided with solid-state imaging device of first embodiment
It has the same shape as 0.

As described above, the transparent film 9 on the upper surface of the pixel separation film 7 is removed, and then the microlens 15 is moved to the flat portion of the pixel separation film 7 based on the procedure described in the solid-state imaging device of the third embodiment. Upper and truncated quadrangular pyramid-shaped pixel separation film 7
And on a part of the flattened transparent film 9 on the inclined side surface. The bottom surface of the micro lens 15 is
Lens 10 (or V-shaped surface) formed on the surface of
Is set so as not to protrude into the area of.

In the solid-state imaging device having such a configuration, incident light (indicated by arrows 16, 17, and 18 in FIG. 4) directly incident on the microlens 15 from the outside is
And the light is reliably irradiated on the light receiving surface of the photoelectric conversion unit 2 through the pixel separation film 7, the insulating film 6, and the interlayer film 3.
The incident light (indicated by an arrow 11 in FIG. 4) incident on the surface of the transparent film 9 near the center of the concave lens 10 (or V-shaped surface) and the incident light (FIG.
Incident light (shown by arrows 12 and 13 in FIG. 4) incident on the peripheral edge side of the concave lens 10
Is refracted on the surface of the pixel film and proceeds in the transparent film 9, and further refracted toward the photoelectric conversion unit 2 by the side surface of the pixel separation film 7. Then, the inside of the pixel separation film 7, the insulating film 6, and the interlayer film 3
To the light receiving surface of the photoelectric conversion unit 2 through the
, A signal charge is excited.

Therefore, in the solid-state imaging device shown in FIG.
Most of the incident light that has entered the inside is irradiated on the light receiving surface of the photoelectric conversion unit 2, and the light sensitivity of the photoelectric conversion unit 2 can be improved.

When the solid-state imaging devices according to the first, second, third, and fourth embodiments of the present invention are applied to a color device or the like, the pixel separation film 7 in each embodiment is simply replaced with a color filter. Is fine. In this case, the refractive index n1 of the color filter is generally about n1 = 1.6. A color filter having a truncated quadrangular pyramid shape is laminated on the insulating film 6 at a predetermined interval at a position facing the photoelectric conversion unit 2.
For example, as a color filter, COLOR MOSAIC CM-8000 manufactured by Fuji Film Orin Co., Ltd.
Is used to laminate with a film thickness of 0.5 μm to 1.0 μm.

The color filter having the shape of a truncated quadrangular pyramid is formed for each arbitrary unit cell including the photoelectric conversion unit 2 and the charge transfer unit, but the pattern of each color filter for an adjacent unit cell is not formed at the same time. The pattern formation of each color filter for one unit cell is performed a plurality of times. In this manner, a truncated quadrangular pyramid-shaped color filter can be provided at a position facing all the photoelectric conversion units 2.

The angle of inclination of the side face of the color filter having a truncated pyramid shape is changed in the range of 40 ° to 80 ° with respect to the horizontal direction depending on the light irradiation amount from the light source and the focal point of the irradiation light.

In the case where a truncated quadrangular pyramid-shaped color filter is used instead of the pixel separation film 7, the center of the concave lens 10 formed on the surface of the transparent film 9 is located at the boundary position of each adjacent color filter (at the end of the groove 8). The lower part of the photoelectric conversion unit 2 is located at a position where incident light passing through an arbitrary color filter is opposed to an adjacent color filter.
Is suppressed, and color mixing due to dimensional variations or the like at the time of processing the microlenses 15 formed on each color filter is prevented.

[0054]

According to the solid-state imaging device of the present invention, a plurality of photoelectric conversion units, which are light receiving units, are provided at regular intervals in a semiconductor substrate. A charge transfer electrode for transferring the generated signal charge is provided between the photoelectric conversion units, and the insulating film is stacked on the semiconductor substrate so that the charge transfer electrode is embedded. A pixel separation film is provided at a position facing the upper photoelectric conversion portion, and a V-shaped groove having a predetermined angle is formed between side surfaces of a pair of adjacent pixel separation films. Thereby, the light sensitivity of the photoelectric conversion unit can be improved, and the smear phenomenon that causes bleeding due to leakage of signal charges from unselected pixels can be suppressed.

[Brief description of the drawings]

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

FIG. 4 is a schematic sectional view of a main part of a solid-state imaging device according to a fourth embodiment of the present invention.

FIG. 5 is a schematic sectional view of a conventional solid-state imaging device.

FIG. 6 is a schematic sectional view of another conventional solid-state imaging device.

FIG. 7 is a schematic sectional view of still another conventional solid-state imaging device.

[Explanation of symbols]

 Reference Signs List 1 semiconductor substrate 2 photoelectric conversion unit 3 interlayer film 4 charge transfer electrode 5 light shielding film 6 insulating film 7 pixel separation film 8 groove 9 transparent film 10 concave lens 11 incident light 12 incident light 13 incident light 14 groove 15 incident light 16 incident light 17 incident Light 18 Incident light 19 Color filter 20 Flattening film 21 Concave lens 22 Intermediate film 23 Concave lens 24 Intermediate film

Claims (8)

[Claims] A plurality of photoelectric conversion units, which are light receiving units, are provided at regular intervals inside a semiconductor substrate, and a signal charge generated by each photoelectric conversion unit is provided on the semiconductor substrate. A solid-state imaging device in which a charge transfer electrode for transferring is provided between each photoelectric conversion unit, and an insulating film is stacked on the semiconductor substrate so as to embed the charge transfer electrode. A pixel separation film is provided at a position facing the photoelectric conversion portion, and a V-shaped groove having a predetermined angle is formed between side surfaces of a pair of adjacent pixel separation films. A solid-state imaging device characterized by the above-mentioned. 2. The solid-state imaging device according to claim 1, wherein each of the pixel separation films is covered with a transparent film, and a transparent film is provided in each of the grooves. 3. The solid-state imaging device according to claim 2, wherein the refractive index of the transparent film is lower than the refractive index of the pixel separation film. 4. The solid-state imaging device according to claim 2, wherein the surface of the transparent film provided in each of the grooves has a concave shape. 5. A transparent film provided in each of the grooves has a cross section V
3. The solid-state imaging device according to claim 2, wherein the solid-state imaging device has a character shape. 6. The solid-state imaging device according to claim 1, wherein a convex lens-shaped microlens is provided on each of the pixel separation films. 7. The solid-state imaging device according to claim 6, wherein a peripheral portion of a bottom surface of each of the microlenses is disposed on the transparent film. 8. The solid-state imaging device according to claim 1, wherein the pixel separation film is a color filter.