JPH0434977A - Solid-state image sensor - Google Patents

Abstract

PURPOSE:To notably lower the flare level by focusing an incident light on a reflection preventive film in an optical black part. CONSTITUTION:A beam of light Po supposed to enter through the intermediary of a seal glass 7 enters in a focusing lenses 6 on an optical black part (OPB). The beam of light Po is reflected at the interface of the focusing lenses 6 to advance toward a dyeing layer 5. Since this dyeing layer 5 functions as a reflection preventive film, the reflected light P1 is dimmed with the dyeing layer 5 so that the intensity of the reflected light P2 from the dyeing layer 5 may satisfactorily be decreased. Accordingly, the reflection of the light focused on the focusing lenses 6 can be avoided thereby enabling the flare level to be satisfactorily lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides an optical black section adjacent to an effective pixel section. In the image sensor, flare is reduced by creating a structure in which the incident light is focused on the anti-reflection film in the optical black area, and by making the condensing ratio of the condensing lens in the optical black area lower than that in the effective pixel area. This will significantly improve the level of

[Conventional technology]

Generally, in a solid-state imaging device such as a CCD image sensor, an optical black section for detecting a black level is disposed adjacent to an effective pixel section that effectively performs photoelectric conversion. This optical black portion is usually formed so as to be covered with a light shielding film made of an aluminum film. In addition, as a technology for achieving high sensitivity, there is a known technology that uses on-chip microlenses that are formed directly on the chip for each pixel (for example, Nikkei Microdevices, June issue, 1
990, pp. 91-92, published by Nikkei BP)
.

Figure 6 shows CO formed with on-chip microlens.
It is a sectional view in D image. A plurality of sensor parts 101 are formed on the surface of the silicon substrate 100 at approximately equal intervals. The area between the sensor parts 101 in the effective pixel area and the optical black area are covered with a light shielding film 102 made of an aluminum film. The light shielding film 102
A dyed layer 103 for antireflection is formed on top, and this dyed layer 103 reduces flare.

A condenser lens 106 is formed on each sensor part 101 for each pixel, and each condenser lens 106 focuses light on the sensor part 101. These condensing lenses 106 are formed to extend not only over the originally required effective pixel area but also over the optical black area in order to reduce unevenness in the process. In other words, if the condenser lens 106 is formed only within the effective pixel area without providing continuity at the interface between the optical black area and the effective pixel area, the curvature of the condenser lens 106 will be different from the center of the effective pixel area. In order to prevent this, the condenser lens 106 is continuously formed even on the originally unnecessary optical black part.

[Problem to be solved by the invention]

However, when the condensing lens 106 is formed continuously on the optical black portion, the condensing lens 106
As a result, the light collection rate increases, and the flare caused by reflection at the light shielding 11102 on the optical black portion becomes more emphasized. In particular, oblique light rays undergo total internal reflection at an angle less than the critical angle of the sealing glass 107, so they may be re-imaged in the effective pixel area, resulting in significant flare and ghosting.

SUMMARY OF THE INVENTION In view of the above-mentioned technical problems, the present invention aims to provide a solid-state imaging device that can significantly improve the flare level.

[Means to solve the problem]

In order to achieve the above object, the solid-state image sensor of the present invention has the following features:
A solid-state image sensor in which an optical black section is provided adjacent to an effective pixel section is characterized in that incident light is focused on an antireflection film in the optical black section. In this optical black part, the structure in which the incident light is focused on the anti-reflection film includes, for example, a structure in which the anti-reflection film is formed on the entire surface of the optical black part, and a structure in which the anti-reflection film is formed on the entire surface of the optical black part, or a structure in which the anti-reflection film is formed on the entire surface of the optical black part, and a structure in which the incident light is focused on the anti-reflection film on the optical black part. Examples include a structure in which an antireflection film is provided, and a structure in which the pitch at which condenser lenses are formed is shifted by half a pixel in the optical black area compared to the effective pixel area.

Further, in another solid-state image sensor of the present invention, in a solid-state image sensor in which an optical black part is provided adjacent to an effective pixel part, the light collection rate of the condensing lens of the optical black part is set such that the light collection rate of the effective pixel part is It is characterized by being lower than that of the lens. The condensing lens with a lower condensing efficiency in the optical black portion may be a flat film itself without a lens shape.

[Effect]

By focusing the incident light on the anti-reflection film in the optical black part, even if the flare component is focused and emphasized by the condensing lens, it will be absorbed by the anti-reflection film.
Therefore, a significant reduction in flare will be achieved in the on-chip microlens structure.

Furthermore, in the solid-state image sensor of the other invention of the present application, the condensing lens in the optical black part has a lower light condensing rate than that in the effective pixel part, so that the emphasis on flare in the optical black part is reduced. Become.

〔Example〕

Preferred embodiments of the present invention will be described with reference to the drawings.

First Embodiment This embodiment is an example of a CCD solid-state image pickup device in which a dyed layer as an antireflection film is formed on the entire surface of an optical black portion.

First, the overall arrangement of pixels has a structure as shown in FIG. FIG. 5 is a plan view of the imaging area viewed from the optical axis direction of incident light. As shown in FIG. Kurobe) Surrounded by OPB. This optical black portion OPB is an area for obtaining a black level reference, and is formed in the front and back in the horizontal direction and in the front and back in the vertical direction, for example, with approximately 2.3W pixels. The effective pixel portion EP has a portion of sensors arranged in a matrix as described later, and photoelectric conversion is performed in a portion of the sensor.

Next, sensor portions 2 are arranged at predetermined intervals on the surface of a silicon substrate 1, a cross section of which is shown in FIG. In this sensor part 2, signal charges are generated in response to incident light, and the signal charges are transferred by vertical registers and horizontal registers (not shown).

FIG. 1 shows a cross section of the boundary between the effective pixel portion EP and the optical black portion OPB, and shows the effective pixel portion E.
In P, the light shielding film 3 made of an aluminum film is formed on the region between each sensor part 20, and the region above each sensor part 2 is made into the opening 4 of the light shielding film 3. Conversely, in the optical black part OPB, the light shielding film 3 uniformly covers the silicon substrate 1, and the optical black part OPB
No light is directly incident on the sensor part 2,
A dyed layer 5 functioning as an antireflection film is formed on each of the light shielding films 3. That is, in the effective pixel part EP, the dyed layer 5 is formed on each light shielding film 3 formed on the area between the sensor parts 2, and in the optical black part OPB, the dyed layer 5 is formed on each light shielding film 3 formed on the area between the sensor parts 2.
A dyed layer 5 is placed on the light shielding film 3 covering the entire surface of the PB.
formed over the This optical black part OP
The dyed layer 5 of B is formed to cover the light shielding M3 and functions to absorb flare as described later.

On the dyed layer 5, a condenser lens 6 is formed for each surface element by processing a lens material layer. That is, on the effective pixel part EP, a condenser lens 6 is arranged above each opening 4, and on the optical black part OPB, the condenser lens 6 is arranged at the same pitch as the condenser lens 6 on the effective pixel part EP. is formed. The condensing lens 6 on the effective pixel portion EP has the function of converging incident light and apparently improving the aperture ratio. Furthermore, since the condenser lens 6 on the optical black portion OPB is formed continuously with that on the effective pixel portion EP,
It becomes possible to maintain the lens shape of the peripheral portion of the effective pixel portion EP to be the same as that of the central portion. A sealing glass 7 is disposed on each such condensing lens 6, and the incident light enters through the sealing glass 7.

In the CCD solid-state image sensor of this example having such a structure,
By the following mechanism, the optical black part ○PB
Flare from the air can be suppressed.

For example, as shown in FIG. 1, when a light ray P is incident through the seal glass 7, the light ray P0 is incident on the condenser lens 6 on the optical black portion OPB. The light ray P is refracted at the interface of the condenser lens 6, and the refracted light P1 is focused while heading toward the dyeing layer 5. Since the dyeing layer 5 functions as an anti-reflection film, the refracted light P1
is weakened by the dyeing layer 5, and the reflected light P2 from the dyeing layer 5
The light intensity is sufficiently small. Therefore, reflection of the light condensed by the condenser lens 6 is prevented, making it possible to sufficiently reduce the level of flare.

In this embodiment, the dyed layer 5 is used as the antireflection film, but other material films may be used as long as they have other antireflection functions and are compatible with the process.

Second Embodiment This embodiment is a modification of the first embodiment, and is an example in which a dyed layer functioning as an antireflection film is provided only under the condenser lens.

The CCD solid-state image pickup device of this embodiment has the main parts shown in FIG. Conforms to what is described.

The structure of this CCD solid-state image sensor will be described with reference to FIG. 2. First, sensor portions 12 for performing photoelectric conversion are arranged on the surface of a silicon substrate 11 at predetermined intervals. In the effective pixel portion EP, a light shielding film 13 made of an aluminum film is formed on a region between each sensor part 12, and the region above each sensor part 12 is an opening 14 of a light shield 1113. . Conversely, in the optical black part OPB, the light shielding film 13 uniformly covers the silicon substrate 11, and the sensor part 1 of the optical black part OPB
No light is directly incident on 2.

On such a light shielding film 13, dyed layers 15a and 15b each functioning as an antireflection film are formed. That is, in the effective pixel portion BP, dyed layers 15a are formed on each light shielding film 13, respectively. This effective pixel portion EP
Since the light shielding M13 is formed in the area between the sensor parts 12, the dyed layer 1 is formed in the area between the sensor parts 12.
5a prevents reflection. In addition, the optical black part OPB covers the entire surface of the area to block light! A plurality of dyed layers 15b are formed on 113. The dyed layer 15b of the optical black part OPB is arranged corresponding to the condensing lens 16 described next, and also corresponds to the sensor part 12 hidden under the light shielding film 13 of the optical black part OPB. Placed. By forming the dyed layer 15b in a pattern for each pixel in this way, it is possible to have continuity in processing with the dyed layer 15a of the effective pixel portion EP, which is advantageous for microfabrication.

On the dyed layers 15a and 15b, a lens material layer is processed to form a condenser lens 16 for each pixel, as in the first embodiment. That is, on the effective pixel part EP, a condenser lens 16 is arranged above each opening 14, and on the optical black part OPB, a condenser lens 16 is arranged at the same pitch as the condenser lens 16 on the effective pixel part EP. 16 is formed. The condenser lens 16 on the effective pixel portion EP has a function of converging incident light and apparently improving the aperture ratio. Also,
The condensing lens 16 on the optical black part OPB is
Since it is formed continuously with that on the effective pixel portion EP, it is possible to maintain the lens shape around the effective pixel portion EP to the same lens shape as the central portion thereof. A sealing glass 17 is arranged on each such condensing lens 16,
Incident light enters through the seal glass 17.

In the CCD solid-state image sensing device of this embodiment having such a structure, as in the first embodiment, the light rays condensed by the condenser lens 6 of the optical black portion OPB are absorbed by the dyed layer 15b, which is an anti-reflection film. The reflection is suppressed, and it is possible to reduce flare. In addition, the dyed layer 15b
The processability is also improved due to the continuity with the dyed layer 15a, which is also advantageous for fine processing.

Third Embodiment This embodiment is an example of a CCD solid-state image pickup device in which the condenser lens on the optical black portion is shifted by a half pitch.

The CCD solid-state image sensor of this embodiment has the main parts shown in FIG. 3, and the relationship between the effective pixel part EP and the optical black part OPB is 5rj! This is similar to that described in the first embodiment using J.

The structure of the CCD solid-state image sensor of this embodiment will be explained with reference to FIG. Sensor units 22 are arranged to perform this. In the effective pixel portion EP, a light shielding 823 made of an aluminum film is formed on the vi area between each sensor part 22, and an N area above each sensor part 22 is formed on the opening 2 in which the light shielding film 23 is opened.
It is considered to be 4. Further, in the optical black portion OPB, the light shielding film 23 uniformly covers the silicon substrate 21, and no light is directly incident on the sensor portion 22 of the optical black portion OPB.

A dyed layer 25, which is an antireflection film, is formed on the light shielding film 23. In the effective pixel portion EP, the dyeing layer 25 is light-shielding 1! They are arranged on the light shielding film 23 in accordance with the pitch of I23. In this effective pixel portion BP, the interval between the dyed layers 25 is equal to the pitch between the light shielding films 23. Next, in the optical black portion OPB, dyed layers 25 are arranged at intervals that are the same as the pitch of the effective pixel portion EP. In this optical black part OPB, the light shielding film 23 is formed uniformly covering the substrate surface, but the dyeing layer 25 is formed in the effective pixel part E.
It is formed by taking over the pattern of P as it is.

A condenser lens 26 is formed on the dyed layer 25 functioning as an antireflection film by processing a lens material layer. This condensing lens 26 has an opening 24 on the effective pixel portion EP.
are formed for each pixel on the top.

A similar condensing lens 26 is also formed on the optical black portion OPB, but the pitch of the condensing lens 26 is will be placed at a position shifted by half a picture. That is, in the effective pixel part BP, the condensing lenses 26 are regularly arranged with a period t, but in the effective pixel part EP and the optical black part OP,
A gap 27 provided at the boundary of B is arranged with a size of 1/2, and a condenser lens 26 is placed above this gap 27.
is not formed, as a result, the optical black part O
In PB, the condensing lenses 26 are again arranged regularly with a period l adjacent to the gap 27, but in the effective pixel area B
When viewed from P, there is a shift by the size of the void portion 27, and as a result, the optical black portion OPB is shifted by half a picture compared to the effective pixel portion EP.

A sealing glass 28 is formed on such a condensing lens 26, and incident light enters through this sealing glass 28.

In the CCD solid-state image sensor of this embodiment, as described above, the pitches of the condensing lenses 26 in the optical black portion OPB are shifted by half a picture. - On the other hand, the lower dyeing layer 25 has an effective pixel part EP and an optical black part OP.
B are arranged continuously at intervals. Therefore, the light collected by the condensing lens 26 of the effective pixel part EP enters the sensor part 22 through the opening 24, but the light collected by the condensing lens 26 of the optical black part OPB is It is collected in the dyed layer 25 of the optical black part OPH. In FIG. 3, light rays QI+Q2 each represent light rays that are condensed by the condensing lens 26 of the optical black portion OPB, and are respectively converged on the dyed layer 25 of the optical black portion OPH. Since the light collected in the dyed layer 25 is prevented from being reflected in this way,
Flare will be reduced.

Fourth Embodiment This embodiment is an example of a CCD solid-state image pickup device in which the condenser lens on the optical black portion is replaced with a flattening film.

The CCD solid-state image sensor of this embodiment has the main parts shown in FIG. 4, and the relationship between the effective pixel section EP and the optical black section OPB is as explained in the first embodiment using FIG. In accordance with

The structure of the CCD solid-state image sensing device of this example will be explained with reference to FIG. Similar to the first embodiment, the CCD solid-state image sensor of this embodiment has a sensor portion 32 on the surface of a silicon substrate 310 for performing charge conversion at predetermined intervals.
are arranged. In the effective pixel portion EP, a light shielding film 33 made of an aluminum film is formed on a region between each sensor part 32, and a region above each sensor part 32 is an opening 34 in which the light shielding film 33 is opened. Ru. Further, in the optical black portion OPB, the light shielding film 33 uniformly covers the silicon substrate 31.

A dyed layer 35, which is an antireflection film, is formed on the light shielding film 33. In the effective pixel portion EP, the dyed layer 35 is arranged on the light shielding film 33 in accordance with the pitch of the light shielding film 33. In the optical black portion OPB, the dyeing layer 35 is continuously formed in a periodic pattern similar to that in the effective pixel portion EP.

In this embodiment, the condensing lens 36 formed on the aperture 34 for each pixel is formed only in the effective pixel part EP, and the condensing lens is not formed in the optical black part OPB and is flattened. Only the film 37 is formed by stacking. The thickness T of the lens material layer for obtaining the flattening film 37 and the condensing lens 36 is made relatively thicker than that of other embodiments. The continuity of the pattern of the lens 36 is maintained by the flattening film 3 instead.
7. By forming the flattening film 37 in the optical black part OPB in this manner, the light collection rate of the optical black part OPB is reduced, and as a result, flare is suppressed from being emphasized. Therefore, flare caused by reflection by the light shielding film 33, which is an aluminum film on the optical black portion OPB, is reduced.

In this embodiment, the condensing lens on the optical black part OPB is made of a flat flattening film, but the invention is not limited to this. Even in such a case, the light condensing efficiency in the optical black portion decreases, so that flare is reduced.

〔Effect of the invention〕

As described above, the solid-state image sensor of the present invention has a structure that focuses light on the antireflection film and a structure that reduces the light collection rate of the optical black part, thereby preventing flare caused by reflection of light incident on the light shielding film of the optical black part. can be reduced. As a result, the solid-state image sensor of the present invention can obtain a high-quality video signal with a low level of flare.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part of an example of a solid-state image sensor of the present invention, FIG. 2 is a cross-sectional view of a main part of another example of a solid-state image sensor of the present invention,
FIG. 3 is a cross-sectional view of a main part of still another example of the solid-state image sensor of the present invention, FIG. 4 is a cross-sectional view of a main part of still another example of the solid-state image sensor of the present invention, and FIG. FIG. 6 is a plan view showing the arrangement of an effective pixel section and an optical black section of a solid-state image sensor, and a sectional view of a main part of an example of a conventional solid-state image sensor. 1.11, 21.31...Silicon substrate 2.12, 2
2.32... Sensor part 3.13, 23.33...
Light-shielding film 4.14, 24.34...openings 5.15a, 15b, 25.35=-dyed layer 6.16.
26.36... Light-shielding film 27... Cavity 37... Flattening film Figure 3 Patent applicant: Sony Corporation Patent attorney Akira Kobu (2 others) Figure 4

Claims (2)

[Claims] (1) A solid-state image sensor in which an optical black portion is provided adjacent to an effective pixel portion, wherein incident light is focused on an antireflection film in the optical black portion. (2) In a faceted image sensor in which an optical black part is provided adjacent to an effective pixel part, the light collection efficiency of the condensing lens in the optical black part is lower than that of the condensing lens in the effective pixel part. Characteristic solid-state image sensor.