KR20100055737A - Image sensor and method for fabricating the same - Google Patents

Image sensor and method for fabricating the same Download PDF

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Publication number
KR20100055737A
KR20100055737A KR1020080114601A KR20080114601A KR20100055737A KR 20100055737 A KR20100055737 A KR 20100055737A KR 1020080114601 A KR1020080114601 A KR 1020080114601A KR 20080114601 A KR20080114601 A KR 20080114601A KR 20100055737 A KR20100055737 A KR 20100055737A
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KR
South Korea
Prior art keywords
image sensor
photodiode
interlayer insulating
trench
insulating film
Prior art date
Application number
KR1020080114601A
Other languages
Korean (ko)
Inventor
최하규
Original Assignee
주식회사 동부하이텍
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Application filed by 주식회사 동부하이텍 filed Critical 주식회사 동부하이텍
Priority to KR1020080114601A priority Critical patent/KR20100055737A/en
Publication of KR20100055737A publication Critical patent/KR20100055737A/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
    • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
    • H01L21/76801—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
    • H01L21/76802—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing by forming openings in dielectrics
    • H01L21/76804—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing by forming openings in dielectrics by forming tapered via holes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14625—Optical elements or arrangements associated with the device
    • H01L27/14629—Reflectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14636—Interconnect structures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
    • H01L27/14685—Process for coatings or optical elements

Abstract

PURPOSE: An image sensor and a manufacturing method thereof are provided to minimize a noise by reflecting the diffused light inputted to a photodiode to a photodiode direction. CONSTITUTION: A semiconductor substrate comprises a photodiode(20) and a CMOS circuit which are arranged according to a pixel. An interlayer layer(30) is formed on the semiconductor substrate. A photoresist pattern is formed on the interlayer insulation layer. The interlayer insulation layer is etched with a reactive ion and the trench is formed. The upper width of the trench is larger than the lower width of that. A copper metal layer is formed on the interlayer insulation layer with the trench. A copper metal wire(40) is formed inside the trench by polishing the copper metal layer.

Description

Image sensor and method for manufacturing the same {image sensor and method for fabricating the same}

In an embodiment, an image sensor and a method of manufacturing the same are disclosed.

The image sensor is a semiconductor device that converts an optical image into an electrical signal, and includes a charge coupled device (CCD) image sensor and a complementary metal oxide silicon (CMOS) image sensor (CIS). do.

The CMOS image sensor implements an image by sequentially detecting an electrical signal of each unit pixel by a switching method by forming a photodiode and a MOS transistor in the unit pixel.

As the design rule of the CMOS image sensor is gradually reduced, the size of the unit pixel may be reduced, thereby reducing the light sensitivity. In order to increase the light sensitivity, a micro lens is formed on the color filter.

However, the light sensitivity may be reduced due to diffraction and scattering of light due to additional structures such as insulating films and metal wirings existing in the optical path from the microlenses to the photodiodes.

1 is a cross-sectional view showing a conventional image sensor.

As shown in FIG. 1, a conventional image sensor includes a semiconductor substrate 1 having a photodiode 2 and an element isolator 6, a metal wiring 4, and an interlayer insulating film 3 formed on the semiconductor substrate 1. And a microlens (0_) formed on the color filter unit (8) and the color filter unit (8) corresponding to each photodiode (2) on the metal line layer (5) and the color filter unit (8). Include.

In general, in the image sensor having a pixel size of 2.25 µm or more, the aluminum wiring of the metal wiring layer 5 has a trapezoidal shape. That is, the lower width of the aluminum wiring is larger than the upper width.

Therefore, when the light received by the photodiode 2 is scattered at the interface between the interlayer insulating films 3 and incident on the sidewall of the aluminum wiring, the incident light is reflected from the sidewall of the aluminum wiring to reduce noise due to the profile characteristic of the sidewall. Will be generated.

In particular, the size of an image sensor has recently been reduced, and an image sensor having a pixel having a size of 1.75 μm or less has a problem in that image quality is degraded due to such noise.

The embodiment provides an image sensor and a method of manufacturing the same, which minimize the noise by reflecting scattered light of light incident to a photodiode in the direction of a photodiode by forming metal wirings of an image sensor having a pixel of 1.75 μm or less by a damascene method. .

The embodiment provides an image sensor and a method for manufacturing the same, which can improve light efficiency and increase light sensitivity by adjusting side profiles of metal wires around an optical path incident from the image sensor to the photodiode.

In an image sensor including a semiconductor substrate including a photodiode and a CMOS circuit arranged for each pixel according to an embodiment and an interlayer insulating film including a metal wiring disposed on the semiconductor substrate, at least an optical path incident to the photodiode The peripheral metal wiring is characterized in that the upper width is greater than the lower width.

In one embodiment, a method of manufacturing an image sensor includes preparing a semiconductor substrate including a photodiode and a CMOS circuit arranged for each pixel, forming an interlayer insulating film on the semiconductor substrate, and forming a photoresist on the interlayer insulating film. Forming a pattern, reactive ion etching the interlayer insulating layer using the photoresist pattern as a mask to form a trench having an upper width greater than a lower width, forming a copper metal film on the trench formed interlayer insulating film; Polishing the copper metal layer to form a copper metal wiring in the trench.

According to the embodiment, metal wirings of an image sensor having a pixel of 1.75 μm or less are formed by a damascene method to reflect scattered light of light incident to a photodiode in the photodiode direction, thereby minimizing noise, improving light efficiency, and improving light sensitivity. There is an effect that can be increased.

An image sensor and a method of manufacturing the same according to an embodiment will be described in detail with reference to the accompanying drawings.

In the description of the embodiments, where described as being formed "on / over" of each layer, the on / over may be directly or through another layer ( indirectly) includes everything formed.

In the drawings, the thickness or size of each layer is exaggerated, omitted, or schematically illustrated for convenience and clarity of description. In addition, the size of each component does not necessarily reflect the actual size.

2 is a cross-sectional view of an image sensor according to an embodiment, and FIG. 3 is an enlarged cross-sectional view of a metal wiring according to an embodiment.

2 and 3, an isolation layer 11 defining an active region and a field region is formed on the semiconductor substrate 10. The unit pixel formed in the active region includes a photodiode 20 for receiving light to generate photocharges and a CMOS circuit connected to the photodiode 20 to convert the received photocharges into electrical signals. .

After the related devices including the unit pixels are formed, the metallization 40 and the interlayer insulating layer 30 are formed on the semiconductor substrate 10.

The interlayer insulating layer 30 may be formed of a plurality of layers. For example, the interlayer insulating film 30 may be formed of a nitride film or an oxide film.

The metal wiring 40 may be formed in the form of wiring embedded in the interlayer insulating film 30 by using a damascene method or the like.

In particular, the metal wires 40 around the optical path incident on the photodiode 20 are formed in the form of wiring embedded in the interlayer insulating film 30 by using a damascene method or the like.

For example, the metal wiring 40 forms a trench 35 in the interlayer insulating film 30 and forms a copper film on the interlayer insulating film 30 including the trench 35 using an electroplating method or the like. Thereafter, the copper film may be polished to expose the interlayer insulating layer by using a chemical mechanical polishing method or the like to form a copper metal wiring 40 embedded in the trench 35.

In forming the metallization 40, a side profile is important. That is, by adjusting the inclination of the sidewall of the metal wire 40, the lower width and the upper width of the metal wire 40, the metal wire 40 is formed in an inverted trapezoidal shape.

Since the metal wiring 40 is formed in the trench 35, it is important to adjust the sidewall profile of the trench 35 to adjust the profile of the metal wiring 40.

If the lower width of the metal wire 40 is a and the upper width is b, a <b is satisfied.

The metal wire 40 may be formed in a plurality of pieces through the interlayer insulating film 30. The metal wire 40 is intentionally laid out so as not to block light incident on the photodiode 20.

The metal wire 40 is disposed at a position other than the light path 70, which is a path through which light is incident on the photodiode 20. Therefore, since light is incident perpendicularly to the semiconductor substrate 10 at the center of the pixel, the metal wiring 40 is laid out so as not to be formed at a portion corresponding to the photodiode 20 perpendicularly, and light is incident at an angle toward the outer portion of the pixel. Therefore, the metal wire 40 may be formed in a portion corresponding to the photodiode 20 vertically, but is not formed in the inclined optical path 70.

In addition, the interlayer insulating layer 30 may include a passivation layer. The passivation layer may be formed of an insulating layer to protect the device from moisture or scratches. For example, the passivation layer may be formed of any one of a silicon oxide film, a silicon nitride film, and a silicon oxynitride film, or may have a structure in which one or more layers are stacked.

The color filter array 80 is formed on the semiconductor substrate 10 including the interlayer insulating layer 30. The color filter array 80 uses dyed photoresist, and one color filter is formed for each unit pixel to separate colors from incident light.

Each of the color filter arrays 80 represents a different color and includes a first color filter, a second color filter, and a third color filter. For example, the first color filter may be a red color filter, the second color filter may be a green color filter, and the third color filter may be formed of a blue color filter.

Although not shown, a planarization layer may be formed on the color filter array 80. The microlenses to be formed in the subsequent process should be formed on the flattened surface. Therefore, since the step due to the color filter array 80 should be eliminated, a planarization layer may be formed on the color filter array 80.

The microlens 90 is formed on the color filter array 80.

In more detail, the interlayer insulating film 30 is formed of an oxide film or a nitride film. In the interface between the interlayer insulating film 30, a part of the incident light is scattered and incident to the surroundings. These scattered light hits the side wall of the metal wire 40 and is reflected and irradiated downward. Therefore, the scattered light may be prevented from interfering with the incident light reflected upwards to reduce the overall light intensity.

The incident light 70 that passes through the color filter and the metal wiring layer 50 through the microlens 90 and enters the photodiode 20, even though a part of the incident light 70 is scattered to the periphery at the insulating film interface, It is reflected by the side profile toward the substrate, i.e. below, so that it does not interfere with the incident light.

In particular, in an image sensor having a pixel of 1.75 μm or less, when the intensity of incident light 70 is weakened by scattered light, the image quality may be greatly affected. By forming the inverted trapezoids 40 using the damascene method, the noise of the image sensor can be minimized.

In addition, the embodiment may improve the light efficiency and increase the light sensitivity by adjusting the side profile of the metal wires 40 around the light path incident from the image sensor to the photodiode 20.

4 to 8 are cross-sectional views illustrating metal wirings according to an embodiment.

Here, among the plurality of interlayer insulating films 30 and the metal wires 40 formed on each interlayer insulating film 30, one interlayer insulating film 30 and a metal wiring formed in the interlayer insulating film 30 are shown as an example. This will be described.

First, an interlayer insulating film is deposited to a thickness of 3000 kV to 9000 kV.

For example, the interlayer insulating film 30 may be formed by depositing a material having a low dielectric constant such as fluorinated silicate glass (FSG) by plasma enhanced chemical vapor deposition (PECVD).

Before forming the interlayer insulating layer 30, an etch stop layer may be further formed on the substrate to prevent etching. The etch stop layer may include a silicon nitride layer (SiN) or a silicon oxynitride layer (SiON).

Referring to FIG. 4, a photoresist pattern 51 is formed on the interlayer insulating layer 30.

Referring to FIG. 5, the trench 35 is formed by etching the interlayer insulating layer 30 using the photoresist pattern 51 as a mask.

The etching process may be made by reactive ion etching, the pressure of 65mT ± 6.5mT, RF power of 1700W ± 100W, Ar flow rate of 380 ± 40 sccm, CO flow rate of 300 ± 30 sccm, C 4 F of 14 ± 3 sccm 8 is carried out under conditions of flow rate.

As a result, the upper width of the trench 35 may be larger than the lower width of the trench 35.

Although not illustrated, a barrier layer may be formed on the interlayer insulating layer 30 including the trench 35. The barrier film may effectively prevent copper diffusion of a copper film to be formed later, and have an effect of improving EM (electromigration) resistance.

The barrier layer may include at least one of Ta, Ti, TaN, TiN, TiSiN, TaSiN.

6, a copper metal film 45 is formed on the interlayer insulating film 30.

The copper metal layer 45 may be formed by, for example, electroplating or the like, or may be formed by PVD or CVD (chemical vapor deposition).

Here, the seed film may be formed before the copper metal film 45 is formed.

Subsequently, referring to FIG. 7, the copper metal film 45 is planarized to form a copper metal wire 40 in the trench 35.

That is, the copper metal film 45 may be formed by chemical mechanical polishing to form the copper metal wire 40 embedded in the trench 35.

In the chemical mechanical polishing process, the barrier film and the seed film formed on the interlayer insulating film 30 are also polished and removed, so that the top surface of the interlayer insulating film 30 may be exposed in a region other than the copper metal wiring 40. Can be.

Referring to FIG. 8, another interlayer insulating film is deposited on the exposed interlayer insulating film 30.

Thereafter, the process of FIGS. 4 to 7 may be repeated to form the metal wiring layer 50 including the plurality of interlayer insulating films and the metal wirings 40 formed on the interlayer insulating film 30.

The metal wire 40 using the damascene method as described above is disposed at least around a path where light is incident on the photodiode 20 and can be applied to all metal wires 40 used in the pixel array region of the image sensor. have.

In addition, the metal wire 40 according to the embodiment may be applied to an image sensor having a pixel size of 1.75 μm or less.

Since the image sensor having a pixel size of 1.75 μm or less has a small light receiving area, and may have a great influence on image quality even with small noise caused by scattered light, the image sensor having a pixel size of 1.75 μm or less to which the embodiment is applied has excellent light sensitivity and efficiency. .

Although described above with reference to the embodiments, which are merely examples and are not intended to limit the present invention. Those skilled in the art to which the present invention pertains are not exemplified above without 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 cross-sectional view showing a conventional image sensor.

2 is a cross-sectional view of an image sensor according to an embodiment, and FIG. 3 is an enlarged cross-sectional view of a metal wiring according to an embodiment.

4 to 8 are cross-sectional views illustrating metal wirings according to an embodiment.

Claims (7)

In an image sensor comprising a semiconductor substrate including a photodiode and a CMOS circuit arranged for each pixel and an interlayer insulating film including a metal wiring disposed on the semiconductor substrate, At least a metal wiring around an optical path incident to the photodiode has an upper width greater than a lower width. The method of claim 1, The metal wiring is an image sensor, characterized in that the copper metal wiring formed by the damascene method. The method of claim 1, And the image sensor has a pixel size of 1.75 μm or less. Preparing a semiconductor substrate including a photodiode and a CMOS circuit arranged for each pixel; Forming an interlayer insulating film on the semiconductor substrate; Forming a photoresist pattern on the interlayer insulating film; Reactive ion etching of the interlayer dielectric layer using the photoresist pattern as a mask to form a trench having an upper width greater than a lower width Forming a copper metal film on the trench formed interlayer insulating film; And Polishing the copper metal layer to form a copper metal wiring in the trench. The method of claim 4, wherein Wherein the trench and the copper metallization are formed at least around a light path incident to the photodiode. The method of claim 4, wherein And the image sensor has a pixel size of 1.75 μm or less. The method of claim 4, wherein The reactive ion etching method of manufacturing an image sensor, characterized in that using the Ar, CO and C 4 F 8 gas.
KR1020080114601A 2008-11-18 2008-11-18 Image sensor and method for fabricating the same KR20100055737A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
KR1020080114601A KR20100055737A (en) 2008-11-18 2008-11-18 Image sensor and method for fabricating the same

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR1020080114601A KR20100055737A (en) 2008-11-18 2008-11-18 Image sensor and method for fabricating the same

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KR20100055737A true KR20100055737A (en) 2010-05-27

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