JP2002083946A - Image sensor - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To realize a high sensitivity, high resolution and compact image sensor. SOLUTION: A blue component of light incident on an image sensor is absorbed by a photoelectric conversion film 21B. A photocharge is generated by applying a voltage between the electrodes 22B-1 and 22B-2 sandwiching the photoelectric conversion film 21B. The generated photocharge is transported to the storage diodes 25B-1 and 25B-2 through the conductors 24B-1 and 24B-2, respectively. The green and red components are similarly conveyed to storage diodes 25G-1 and 25G-2 and 25R-1 and 25R-2, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image sensor used for, for example, a television camera and having a light receiving element having a plurality of photoelectric conversion films.

[0002]

2. Description of the Related Art In a conventional television camera, incident light is separated into three primary colors of red, green and blue by a color separation prism, and faithful color reproduction and high resolution are realized by light receiving elements corresponding to the respective colors. Although such a configuration is excellent in performance, it requires a color separation prism and three light receiving elements, and thus has a disadvantage of increasing the size of the television camera.

In order to solve such inconvenience, an on-chip color filter single-plate image sensor including one light receiving element and a filter corresponding to each pixel has been proposed. Are shown in FIGS. 1 and 2, respectively.

Such an image sensor has a vertical transfer C
Light receiving element 5 on which CDs 1a-1d, photodiodes 2a-2d, vertical transfer CCD 3 and signal output unit 4 are formed
And vertical transfer CCD electrodes 6a-6d and light shielding metal films 7a-7d respectively corresponding to the vertical transfer CCDs 1a-1d.
And on-chip color filters 8a-8d.
In FIG. 1, R, G, and B are assigned to the on-chip color filters corresponding to red, green, and blue, respectively. In addition,
As shown in FIG. 3, instead of the red, green, and blue on-chip color filters, complementary color on-chip color filters of Ye, Cy, Mg, and G can be used.

[0005] However, such an image sensor has disadvantages that light use efficiency is reduced and resolution is deteriorated. In order to solve such inconveniences, for example, a light receiving element having a plurality of photoelectric films as described in Japanese Patent Application No. 11-178413 has been proposed, and this is shown in FIG.

Such a light receiving element is an n ⁺ type c-Si
An electrode 12 formed on one side of the c-Si substrate 11 and made of, for example, Al;
N-type a-SiC formed on the other side of Si substrate 11
_z : O13, a nanosilicon layer 14 formed thereon as a first photoelectric conversion film for absorbing red light, and a second silicon oxide layer formed thereon thereon for absorbing green light and nano silicon layer 15 is formed thereon, blue nano silicon layer 16 as the third photoelectric conversion layer that absorbs light, a p-type formed on the a-SiC _z: O
And a transparent electrode 18 formed thereon, for example, made of ITO, a terminal 19 for applying a positive bias to the electrode 12, and a terminal 20 for applying a negative bias to the transparent electrode 18.

Each of the nanosilicon layers 14-16 is composed of silicon (SiO ₂ ) crystal grains of several nanometers, and the grain size is such that the nanosilicon layer 15 is smaller than the nanosilicon layer 14, Nanosilicon layer 16 is smaller than layer 15.

By using such a light receiving element, a high-sensitivity, high-resolution and compact image sensor, that is, a high-resolution single-chip camera can be realized.

[0009]

However, in the above-mentioned Japanese Patent Application No. 11-178,413 or the like, there is no specific proposal for reading out the charge, that is, the signal from each of these photoelectric conversion films. As a result, a high-sensitivity, high-resolution, compact image sensor having such a light receiving element cannot be realized.

An object of the present invention is to provide a highly sensitive, high resolution and compact image sensor.

[0011]

According to the present invention, there is provided an image sensor, comprising: a plurality of photoelectric conversion films sequentially arranged corresponding to mutually different colors; a transparent insulating layer disposed between the photoelectric conversion films; In order to read out the electric charges generated in the plurality of photoelectric conversion films, a reading means electrically connected to each of the plurality of photoelectric conversion films is provided.

According to the present invention, the electric charges generated in the plurality of photoelectric conversion films are read out by the readout means electrically connected to the plurality of photoelectric conversion films, respectively. The present invention can be applied to a sensor, and as a result, a high-sensitivity, high-resolution, compact image sensor can be realized.

For example, the plurality of photoelectric conversion films are three photoelectric conversion films respectively corresponding to three primary colors of red, green and blue.

Preferably, electrodes are respectively formed on both surfaces of the plurality of photoelectric conversion films, and an electrode which is most distant from an electrode to which light is first incident is made opaque and / or
Alternatively, an opaque insulating layer adjacent to the most distant electrode is provided. This makes it possible to omit a light-shielding film required when forming a light receiving element, and thus to more easily realize a high-sensitivity, high-resolution, and compact image sensor.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image sensor according to the present invention will be described in detail with reference to the drawings. FIG.
FIG. 1 is a diagram illustrating a first embodiment of an image sensor according to the present invention. FIG. 5 shows a cross section of three photoelectric conversion films 21R, 21B, and 21B respectively corresponding to the three primary colors of red, green, and blue in a region corresponding to two pixels.

In this case, in order for light to be incident on the layer that senses light of a relatively short wavelength before the layer that senses light of a relatively long wavelength, the photoelectric conversion corresponding to the red photosensitive layer is performed. Conversion film 21R, photoelectric conversion film 21 corresponding to green photosensitive layer
The photoelectric conversion films 21B corresponding to the G and blue photosensitive layers are arranged in order from the bottom.

These photoelectric conversion films 21R, 21B and 21R
B, on both sides, electrodes 22R-1 and 22R-2, 22G
-1 and 22G-2 and 22B-1 and 22B-2. These electrodes 22R-1 and 22R-2, 22G
-1 and 22G-2 and 22B-1 and 22B-2, only the electrode 22R-1 is an opaque electrode, and the others are transparent electrodes.

Also, the electrodes 22R-1, 22G-1 and 2
A bias voltage Vb is applied to 2B-1, and transparent insulating layers 23-1, 23-2, and 23-3 are provided to electrically insulate the photoelectric conversion films 21R, 21B, and 21B from each other. Note that the transparent insulating layer 23-1 may be an opaque insulating layer as described later.

In this embodiment, the reading means is used as the corresponding photoelectric conversion films 21R, 21G and 21B, ie, the electrodes 2
Conductors 24R-1 and 24R-2, 24G-1 and 24 electrically connected to 2R-1, 22G-1 and 22B-1
G-2 and 24B-1 and 24B-2, and storage diodes 25R-1 and 25R-2, 25G-1 and 25G
-2 and 25B-1 and 25B-2, and vertical transfer CC
D26R-1 and 26R-2, 26G-1 and 26G-
2 and 26B-1 and 26B-2, and vertical transfer CCD
Electrodes 27R-1 and 27R-2, 27G-1 and 27G
-2 and 27B-1 and 27B-2.

Of these components, the conductors 24R-1 and 24R-2, 24G-1 and 24G-2, and 24B
-1 and 24B-2 and the vertical transfer CCD electrode 27R-1
And 27R-2, 27G-1 and 27G-2 and 27
B-1 and 27B-2 are formed in the transparent insulating layer 23-1, and the storage diodes 25R-1 and 25R-2, 25G
-1 and 25G-2 and 25B-1 and 25B-2
And vertical transfer CCDs 26R-1 and 26R-2, 26G
-1 and 26G-2 and 26B-1 and 26B-2 are formed in the substrate 28.

The operation of this embodiment will be described with reference to FIG. In FIG. 6, the vertical transfer CCD 26R-
1 and 26R-2, 26G-1 and 26G-2 and 2
Channel stoppers 31-3 respectively adjacent to 6B-1
6 and the vertical transfer CCDs 26R-1 and 26R-2, 26
Vertical transfer CC to G-1 and 26G-2 and 26B-1
The terminals 37 and 38 to which the D drive pulse is applied, the horizontal transfer CCD 39, the terminals 40 and 41 to which the horizontal transfer CCD drive pulse is applied, and the signal output terminal 42 are shown.

The blue component of the light incident on the image sensor is absorbed by the photoelectric conversion film 21B. A photocharge is generated by applying a voltage between the electrodes 22B-1 and 22B-2 sandwiching the photoelectric conversion film 21B. The generated photocharge is transported to the storage diodes 25B-1 and 25B-2 through the conductors 24B-1 and 24B-2, respectively.

The green component of the light incident on the image sensor is absorbed by the photoelectric conversion film 21G. Photocharge is generated by applying a voltage between the electrodes 22G-1 and 22G-2 sandwiching the photoelectric conversion film 21G. The generated photocharge is transported to the storage diodes 25G-1 and 25G-2 through the conductors 24G-1 and 24G-2, respectively.

The red component of the light incident on the image sensor is absorbed by the photoelectric conversion film 21R. Photocharge is generated by applying a voltage between the electrodes 22R-1 and 22R-2 sandwiching the photoelectric conversion film 21R. The generated photocharge is transported to the storage diodes 25R-1 and 25R-2 through the conductors 24R-1 and 24R-2, respectively.

Storage diodes 25R-1 and 25R-
2,25G-1 and 25G-2 and 25B-1 and 2
5B-2 is a vertical transfer CCD 26R-1 and 26R-2, 26G-1 and 26G-2 and 26B of the corresponding color.
-1. Vertical transfer CCD26R
-1 and 26R-2, 26G-1 and 26G-2 and 26B-1 respectively correspond to the corresponding vertical transfer CCDs.
And the output of each color is obtained from the signal output unit 42.

Next, a first embodiment of the image sensor according to the present invention will be described.
The manufacturing process according to the embodiment will be described with reference to FIGS. The corresponding components are denoted by the same reference numerals as in FIG.

First, in the first step, the storage diodes 25R-1 and 25R-2, 25G-1 and 25G
-2 and 25B-1 and 25B-2 and vertical transfer CCD
26R-1 and 26R-2, 26G-1 and 26G-2
And vertical transfer CCD electrodes 27R-1 and 27R-2, 27G-1 on a substrate 28 on which
And 27G-2, 27B-1 and 27B-2, and the transparent insulating layer 23-1, and perform a planarization process (FIG. 7).

Next, in the second step, the transparent insulating film 23-1 is subjected to anisotropic etching to form fine through holes, and the conductive wires 24R-1, 24R-2, 24G-
1 and 24G-2 and at least a part of 24B-1 and 24B-2 (FIG. 8).

Next, in a third step, the electrode 22
Deposit R-1, pixel separation and leads 24R-1 and 24
Etching for separation of R-2, 24G-1 and 24G-2 and 24B-1 and 24B-2 is performed (FIG. 9).

Next, in a fourth step, a photoelectric conversion film 21R is deposited (FIG. 10). Next, in a fifth step, a through hole is formed in the photoelectric conversion film 21R, and an insulating material is embedded therein (FIG. 11).

Next, in a sixth step, a fine through-hole is formed by performing anisotropic etching on the portion in which the insulating material is embedded in the fifth step, and the conductive wires 24G-1 and 24G are formed.
G-2 and part of 24B-1 and 24B-2 (FIG. 12).

Next, in a seventh step, the electrode 22
Deposit R-2, pixel separation and leads 24G-1 and 24G
G-2, 24B-1 and 24B-2 are etched for insulation, and a transparent insulating layer 23-2 is formed thereon (FIG. 13).

Next, in an eighth step, a through hole is formed in the transparent insulating layer 23-2 formed in the seventh step,
Conductors 24G-1 and 24G-2 and 24B-1 and 2
A part of 4B-2 is formed (FIG. 14).

Next, in a ninth step, the electrode 22
G-1 is deposited, pixel separation and leads 24B-1 and 24
Etching for separating B-2 is performed (FIG. 15). Next, in a tenth step, a photoelectric conversion film 21G is deposited (FIG. 16).

Next, in an eleventh step, a through hole is formed in the photoelectric conversion film 21G, and an insulating material is buried therein (FIG. 17). Next, in the twelfth step, the eleventh
Anisotropic etching is performed on the portion in which the insulating material is embedded in the step to form fine through holes, a part of the conductive wires 24B-1 and 24B-2 is formed, and an electrode 22G-2 is deposited thereon, Etching is performed for pixel separation and insulation of the conductive wires 24B-1 and 24B-2 (FIG. 18).

Next, in a thirteenth step, a transparent insulating layer 23-3 is deposited, a through hole is formed therein,
Form part of 4B-1 and 24B-2 (FIG. 19).
Next, in a fourteenth step, an electrode 22B-1 is deposited, and etching for pixel separation is performed (FIG. 20).

Next, in a fifteenth step, a photoelectric conversion film 21B is deposited (FIG. 21). Next, in a sixteenth step, a through hole for pixel separation is formed in the photoelectric conversion film 21B, and a transparent insulating material is embedded therein (FIG. 2).
2). Finally, in a seventeenth step, the electrode 22B-
By depositing No. 2, an image sensor as shown in FIG. 5 is formed (FIG. 23).

In the conventional image sensor, in order to prevent light which has reached the lowermost layer but has not been absorbed but is absorbed by the signal readout circuit, photo-charge is prevented from being generated.
A light shielding film is formed on the signal transfer circuit. In the present embodiment, by making only the electrode 22R-1 opaque, it also has the function of the light-shielding film, and the manufacturing process can be omitted. The same effect can be obtained by making the transparent insulating film 23-1 opaque.

FIG. 24 is a diagram showing a second embodiment of the image sensor according to the present invention. This image sensor includes vertical transfer CCDs 26R-1 and 26R-2, 26G.
-1 and 26G-2 and 26B-1 and 26B-2
And vertical transfer CCD electrodes 27R-1 and 27R-2,2
7G-1 and 27G-2 and 27B-1 and 27B-
2 instead of the vertical signal lines 51R-1 and 51R.
-2, 51G-1 and 51G-2, 51B-1 and 51B-2, and signal readout electrodes 52R-1 and 52R-
2,52G-1 and 52G-2 and 52B-1 and 5
2B-2.

The image sensor shown in FIG. 24 has the same effect as the image sensor shown in FIG. 5, and can be manufactured in the same manner as the manufacturing process described with reference to FIGS.

The present invention is not limited to the above-described embodiment, and many modifications and variations are possible. For example, in the above-described embodiment, a case has been described in which the plurality of photoelectric conversion films are three photoelectric conversion films respectively corresponding to the three primary colors of red, green, and blue. However, complementary photoelectric colors of Ye, Cy, Mg, and G are used. Any number of photoelectric conversion films corresponding to other colors can also be used.

[Brief description of the drawings]

FIG. 1 is a block diagram of a conventional on-chip color filter single-plate image sensor.

FIG. 2 is a cross-sectional view of a conventional on-chip color filter single-plate image sensor.

FIG. 3 is a block diagram of another conventional on-chip color filter single-plate image sensor.

FIG. 4 is a diagram showing a linear enemy of a light receiving element having a plurality of photoelectric conversion films.

FIG. 5 is a diagram showing a first embodiment of an image sensor according to the present invention.

FIG. 6 is a diagram for explaining the operation of the first embodiment of the image sensor according to the present invention.

FIG. 7 is a diagram showing a first step of the manufacturing process of the image sensor according to the present invention.

FIG. 8 is a diagram showing a second step of the manufacturing process of the image sensor according to the present invention.

FIG. 9 is a view showing a third step of the manufacturing process of the image sensor according to the present invention.

FIG. 10 is a view showing a fourth step in the process of manufacturing the image sensor according to the present invention.

FIG. 11 is a view showing a fifth step of the manufacturing process of the image sensor according to the present invention.

FIG. 12 is a view showing a sixth step of the manufacturing process of the image sensor according to the present invention.

FIG. 13 is a view showing a seventh step of the manufacturing process of the image sensor according to the present invention.

FIG. 14 is a view showing an eighth step of the manufacturing process of the image sensor according to the present invention.

FIG. 15 is a view showing a ninth step of the process of manufacturing the image sensor according to the present invention.

FIG. 16 is a diagram showing a tenth step in the process of manufacturing the image sensor according to the present invention.

FIG. 17 is a view showing an eleventh step of the manufacturing process of the image sensor according to the present invention.

FIG. 18 is a diagram showing a twelfth step of the process for manufacturing the image sensor according to the present invention.

FIG. 19 is a diagram showing a thirteenth step of the process of manufacturing the image sensor according to the present invention.

FIG. 20 is a view illustrating a fourteenth step of the process for manufacturing the image sensor according to the present invention.

FIG. 21 is a diagram showing a fifteenth step of the process of manufacturing the image sensor according to the present invention.

FIG. 22 is a view illustrating a sixteenth step of the process of manufacturing the image sensor according to the present invention.

FIG. 23 is a view illustrating a seventeenth step of the manufacturing process of the image sensor according to the present invention.

FIG. 24 is a diagram showing a second embodiment of the image sensor according to the present invention.

[Explanation of symbols]

1a, 1b, 1c, 1d, 26R-1, 26R-2, 2
6G-1, 26G-2, 26B-1, 26B-2 Vertical transfer CCD 2a, 2b, 2c, 2d Photodiode 3,39 Horizontal transfer CCD 4,42 Signal output unit 5 Light receiving element 6a, 6b, 6c, 6d, 27R-1, 27R-2, 2
7G-1, 27G-2, 27B-1, 27B-2 Vertical transfer CCD electrodes 7a, 7b, 7c, 7d Light shielding metal film 8a, 8b, 8c, 8d On-chip color filter 11, 28 Substrate 12, 22R-1, 22R-2, 22G-1, 22G-
2,22B-1,22B-2 electrodes 13,17 _a-SiC z: O 14,15,16 nano silicon layer 18 transparent electrodes 19,20,37,38,40,41 terminals 21R, 21G, 21B photoelectric conversion film 23-1, 23-2, 23-3 Transparent insulating layer 24R-1, 24R-2, 24G-1, 24G-2, 2
4B-1, 24B-2 conducting wire 25R-1, 25R-2, 25G-1, 25G-2, 2
5B-1, 25B-2 Storage diodes 31, 32, 33, 34, 35, 36 Channel stoppers 51R-1, 51R-2, 51G-1, 51G-2, 5
1B-1, 51B-2 vertical signal lines 52R-1, 52R-2, 52G-1, 52G-2, 5
2B-1, 52B-2 signal readout electrode

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshiyuki Hirano 1-10-11 Kinuta, Setagaya-ku, Tokyo Japan Broadcasting Corporation Broadcasting Research Institute F-term (reference) 4M118 AA01 AA10 AB01 BA08 BA10 CA15 CB05 CB14 GC08 GC09 GC14 5C024 AX01 CX41 CY47 DX01 EX52 GX07 GY01 5C065 BB42 BB48 CC01 DD17

Claims (3)

[Claims] 1. A plurality of photoelectric conversion films sequentially arranged corresponding to mutually different colors, a transparent insulating layer respectively disposed between the photoelectric conversion films, and a charge generated in the plurality of photoelectric conversion films are read out. An image sensor comprising: readout means electrically connected to the plurality of photoelectric conversion films. 2. The image sensor according to claim 1, wherein said plurality of photoelectric conversion films are three photoelectric conversion films respectively corresponding to three primary colors of red, green and blue. 3. An electrode is formed on each of both surfaces of the plurality of photoelectric conversion films, and an electrode which is the most distant from an electrode to which light is first incident is made opaque and / or adjacent to the most distant electrode. 3. The image sensor according to claim 1, wherein an opaque insulating layer is provided.