KR20110079333A - Stacked Image Sensor - Google Patents

Abstract

Stacked image sensor according to the embodiment comprises a semiconductor substrate; A plurality of first photodiodes formed on the semiconductor substrate and forming a first stack; A plurality of second photodiodes formed on the semiconductor substrate below the first photodiode and forming a second stack; A plurality of transistors formed on the semiconductor substrate between the first photodiodes; An interlayer insulating layer formed on the semiconductor substrate; And a color filter layer formed on the interlayer insulating layer and formed of a complementary color filter pattern.

According to the embodiment, the photodiodes of the stacked structure are divided into potential barrier layers, the color filter layers are formed by complementary color filter patterns forming various arrays, and the integration degree of the image sensor is increased by adjusting the spacing of the metal structures of the interlayer insulating layers. At the same time, high sensitivity can be realized.

Stacked image sensor, complementary color filter pattern, Bayer pattern, potential barrier

Description

Stacked Image Sensors {Image sensor of tacked type}

Embodiments relate to stacked image sensors.

Recently, pixel size of image sensor is getting smaller for high resolution, and the size is approaching the optical limit. In this situation, several similar technologies have been proposed to have a high performance pixel structure while maintaining high sensitivity.

In particular, through the potential barrier structure, the stacked photodiode is applied to the 4T operation method and the CDS scheme, and scale-down is performed by eliminating the need for the junction for reading the signal of the photodiode present in each layer. A two photodiode stacked pixel structure has been developed which makes this possible.

However, in this case, although the corresponding color signals having different transmission coefficients can be extracted depending on the depth of the substrate, when the combination of the color filters is not appropriate, color reproduction is poor and abnormal signals are generated.

1 is a view illustrating a Bayer pattern of a color filter used in a conventional stacked image sensor, and FIG. 2 is a graph measuring a phenomenon in which a signal is distorted when a combination of color filters is not appropriate.

In the green and blue Bayer pattern as shown in FIG. 1, the color reproducibility is reduced on the stacked image sensor, and as shown in FIG. 2, the distortion signal A is generated by the red signal in the blue wavelength band of about 0.46 nm. have.

The embodiment provides a stackable image sensor capable of increasing integration of an image sensor and realizing high sensitivity.

Stacked image sensor according to the embodiment comprises a semiconductor substrate; A plurality of first photodiodes formed on the semiconductor substrate and forming a first stack; A plurality of second photodiodes formed on the semiconductor substrate below the first photodiode and forming a second stack; A plurality of transistors formed on the semiconductor substrate between the first photodiodes; An interlayer insulating layer formed on the semiconductor substrate; And a color filter layer formed on the interlayer insulating layer and formed of a complementary color filter pattern.

According to the embodiment, the following effects are obtained.

The photodiodes of the stacked structure are divided into potential barrier layers, and the color filter layers are composed of complementary color filter patterns forming various arrays. Can be implemented.

With reference to the accompanying drawings, a stack-type image sensor according to an embodiment will be described in detail.

3 is a graph measuring a color spectrum of a filter pattern used in a stacked image sensor according to an embodiment.

The filter pattern used in the stacked image sensor according to the embodiment may be a complementary color filter pattern. For example, a white / cyan complementary color filter pattern may be used.

Referring to FIG. 3, it can be seen that the complementary color filter has significantly less distorted color signals present in the wavelength range of light than in FIG. 2.

4 is a diagram illustrating a filter pattern used in the stacked image sensor according to the embodiment.

(A) of FIG. 4 illustrates a complementary color filter pattern of white / cyan, (b) illustrates a complementary color filter pattern of white / red / cyan / green. c) illustrates a case in which the complementary color filter patterns of white / red / cyan / green have a four-stage structure.

5 is a circuit diagram schematically showing a configuration of a stacked image sensor according to an embodiment, and FIG. 6 is a side cross-sectional view schematically showing the configuration of a stacked image sensor according to an embodiment.

5 and 6, the stacked image sensor according to the embodiment is an image sensor in which two photodiodes form a stacked structure.

Referring to FIG. 6, a plurality of first photodiodes 120 forming a first stack is formed on an upper portion of the semiconductor substrate 100, and a plurality of second photodiodes 105 forming a second stack are formed below the semiconductor substrate 100. Is formed.

A first potential barrier layer 122 is formed between the first photodiode 120 and the second photodiode 105 to separate the first stack from the second stack.

For example, the first photodiode 120 and the second photodiode 105 may be formed by implanting a second conductivity type impurity ion, and the first potential barrier layer 122 may have a first conductivity type. Impurity ions may be implanted and formed.

In the embodiment, the first conductivity type impurity ions are P-type ions, and the second conductivity type impurity ions are N-type ions.

In addition, the first photodiode 120 may be formed to a depth of 0.01um to 2um from the surface of the semiconductor substrate 100, the first potential barrier layer 122 is to be formed to a depth of 2um to 3um. The second photodiode 105 may be formed to a depth of 3um to 5um.

Therefore, the transmission depth for each color of light may be adjusted by the first potential barrier layer 122.

A second potential barrier layer 110 is formed between adjacent unit cells of the first photodiode 120 and the second photodiode 105 to form two first photodiodes 120 and a second photo for each stack. The diodes 105 are separated to form a unit cell.

A plurality of transistors 131 to 134 are formed on the semiconductor substrate 100 between the first photodiodes 120, respectively, two photodiodes 120 of the first stack and two of the second stack. Process the signals of two photodiodes.

An interlayer insulating layer 140 including metal structures 141 and 142 is formed on the semiconductor substrate 100, and the metal structures 141 and 142 are formed of a plurality of metal wires 141 and contacts 142. It may include.

The color filter layer 150 formed of the complementary color filter pattern is formed on the interlayer insulating layer 140, and the planarization protective layer 160 is formed on the color filter layer 150.

As illustrated through FIG. 4, the complementary color filter pattern may configure various pattern arrays on the color filter layer 150.

In addition, the microlens 170 is formed on the planarization protection layer 160.

FIG. 7 is a diagram simulating light transmission efficiency when the interval between the metal structures 141 and 142 according to the embodiment is adjusted.

As in the embodiment, by using the structure of the first potential barrier layer 122, the color filter layer 150 of the complementary color filter pattern, and adjusting the interval of the metal structures (141, 142) can also adjust the horizontal light path. have.

Therefore, it is possible to improve the sensitivity of the image sensor by minimizing light interference between adjacent pixels.

As shown in FIG. 7, when the interval between the metal structures 141 and 142 is adjusted with respect to the medium wavelength light of 480 nm to 580 nm and the long wavelength light of 580 nm to 700 nm, it is understood that the light transmission efficiency is improved.

Although described above with reference to the embodiments are only examples and are not intended to limit the invention, those of ordinary skill in the art to which the present invention does not exemplify the above within the scope not departing from the essential characteristics of the present invention. It will be appreciated that many variations and applications are possible. For example, each component specifically shown in the embodiments of the present invention can be modified and implemented. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

1 is a diagram illustrating a Bayer pattern of a color filter used in a conventional stacked image sensor.

2 is a graph measuring a phenomenon in which a signal is distorted when a combination of color filters is not appropriate.

3 is a graph measuring a color spectrum of a filter pattern used in a stacked image sensor according to an embodiment.

4 illustrates a filter pattern used in a stacked image sensor according to an embodiment.

5 is a circuit diagram schematically illustrating a configuration of a stacked image sensor according to an embodiment.

6 is a side cross-sectional view schematically showing the configuration of a stacked image sensor according to the embodiment.

7 is a view simulating the optical transmission efficiency when adjusting the interval of the metal structure according to the embodiment.

Claims (10)

Semiconductor substrates; A plurality of first photodiodes formed on the semiconductor substrate and forming a first stack; A plurality of second photodiodes formed on the semiconductor substrate below the first photodiode and forming a second stack; A plurality of transistors formed on the semiconductor substrate between the first photodiodes; An interlayer insulating layer formed on the semiconductor substrate; And And a color filter layer formed on the interlayer insulating layer and comprising a complementary color filter pattern. The method of claim 1, wherein the color filter layer Stacked image sensor comprising at least one of a white / cyan complement color filter pattern and a white / red / cyan / green complement color filter pattern. The method of claim 1, wherein the complementary color filter pattern Stacked image sensor, characterized in that to form a variety of pattern array structure on the color filter layer. The method of claim 1, And a first potential barrier layer formed between the first photodiode and the second photodiode to separate the first stack and the second stack. 5. The method of claim 4, The first photodiode and the second photodiode are formed by implanting a second conductivity type impurity ion, And the first potential barrier layer is formed by implanting first conductivity type impurity ions. The method of claim 5, And the first conductivity type impurity ion is a P type ion and the second conductivity type impurity ion is an N type ion. The method of claim 1, The first photodiode is formed to a depth of 0.01um to 2um from the surface of the semiconductor substrate, the second photodiode is a stacked image sensor, characterized in that formed in a depth of 3um to 5um. 5. The method of claim 4, The first potential barrier layer is a stacked image sensor, characterized in that formed in a depth of 2um to 3um from the surface of the semiconductor substrate. The method of claim 1, And a second potential barrier layer formed between adjacent unit cells of the first photodiode and the second photodiode and separated to form a unit cell for each stack. The method of claim 1, wherein the interlayer insulating layer A metal structure comprising at least one of metallization and contacts, The metal structure is a stacked image sensor, characterized in that to increase the light transmission efficiency by adjusting the distance between each other.

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