KR20070068583A - Cmos image sensor and method for manufacturing threrof - Google Patents

Abstract

A CMOS image sensor and its fabricating method are provided to enhance the photo sensitivity by shortening a distance between a microlens and a photodiode. An isolation film(13) is formed on a semiconductor substrate(11) to define an active region and a field region. Photodiodes(14a to 14c) are formed in the active region. An interlayer dielectric(15) is formed on the semiconductor substrate, and metal wiring layers and metallic interlayer dielectrics(18,20) are formed on the interlayer dielectric. A final metal wiring(24) is formed on the uppermost metallic interlayer dielectric, and a planarized film(25) is formed on the final metal wiring. A microlens(26) is formed on the planarized film and a silicon film(16) is formed between upper portions of red and green regions and the final metal wiring.

Description

CMOS image sensor and its manufacturing method {CMOS IMAGE SENSOR AND METHOD FOR MANUFACTURING THREROF}

1 is a cross-sectional structural view of a CMOS image sensor according to the prior art.

2A to 2D are sequential process cross-sectional views showing a method of manufacturing a CMOS image sensor according to a first embodiment of the present invention.

3A to 3E are sequential process cross-sectional views showing a method of manufacturing a CMOS image sensor according to a second embodiment of the present invention.

4A to 4D are cross-sectional views sequentially illustrating a method of manufacturing a CMOS image sensor according to a third exemplary embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

11 semiconductor substrate 12 p-type epi layer

13: device isolation layer 14a: red photodiode

14b: green photodiode 14c: blue photodiode

15 interlayer insulating film 16 first silicon film

The present invention relates to a method for manufacturing a CMOS image sensor, and more particularly, to a CMOS image sensor and a method for manufacturing the same, which can improve light sensitivity by reducing a distance between a microlens and a photodiode.

In general, a complementary MOS image sensor uses a CMOS technology that uses a control circuit and a signal processing circuit as peripheral circuits to form photodiodes and MOS transistors in a unit pixel. By using this, an image is realized by adopting a switching method of sequentially detecting an output.

The CMOS image sensor is composed of a light sensing part that receives and receives light from the outside to generate and accumulate photocharges, and a logic circuit part that processes the detected light into an electrical signal to make data. Efforts have been made to increase the fill factor of the photosensitive portion to the total area, and the most commonly used method is to form microlenses.

That is, in order to increase the light sensitivity, a condensing technology that changes the path of light incident to the areas other than the light sensing portion and collects the light sensing portion has emerged. For this purpose, the image sensor uses a microlens on the Cali filter. The method of forming is used.

In the prior art, microlenses are typically formed using photoresist, and the structure of the CMOS image sensor including the color filter and the microlens will be described as follows.

1 is a cross-sectional structural view of a CMOS image sensor according to the prior art.

First, an element isolation film 2 defining an active region and a field region is formed on the semiconductor substrate 1, and photosensitive means, that is, a photodiode 3, formed of a photodiode or the like is formed in each unit pixel. . In this case, notation and description of each transistor constituting the unit pixel will be omitted.

As such, a plurality of interlayer insulating films 4 and a plurality of metal wires 5 are formed on the semiconductor substrate 1 on which the device isolation film 2, the photodiode 3, and transistors (not shown) are formed.

The final metal wiring 6 is formed on the upper portion of the lower structure, and the protective film 7 is formed on the top of the final metal wiring 6 to protect the device from moisture, scratches, and the like.

A color filter 8 for implementing a color image is formed on the passivation layer 7. A color filter typically uses a dyed photoresist, and one color filter 8 is formed for each unit pixel. It is formed to separate the color from the light incident on the photodiode (3).

At this time, the microlens to be formed in a subsequent process must be formed on the flattened surface to exhibit the best performance. Therefore, the level difference due to the color filter must be eliminated, and thus the flattening film 9 is formed on the color filter 8. The microlens 10 is formed on the planarization film 9.

However, in the CMOS image sensor, the number of wiring layers is gradually increased according to the miniaturization and the high integration of the device, and the increase in the wiring becomes a problem of increasing the distance between the photodiode and the microlens.

Increasing the distance between the photodiode and the microlens according to the increase in the wiring will cause the focus dispersion and scattering of the light incident on the photodiode, thereby reducing the photosensitivity.

In addition, there is a problem that light passing through the color filter is scattered or dispersed, causing cross talk to adjacent photodiodes.

In order to prevent crosstalk to the photodiode, the radius of curvature of the microlens may be increased, but the radius of curvature of the microlens may be increased, and the color filter may be formed of organic photoresist (PR). Since it is difficult to withstand high temperatures and to form metal wires after the color filter is formed, there is a problem in that the color filter cannot be formed close to the photodiode.

An object of the present invention for solving the problems according to the prior art, by using a difference in the depth and absorption rate of the permeation of silicon in accordance with the wavelength of the light to separate the color of the silicon film near the photodiode with a color filter object The present invention provides a CMOS image sensor and a method of manufacturing the same, which have a different thickness for each region to reduce a gap between a microlens and a photodiode.

In addition, the present invention is to provide a CMOS image sensor and a method of manufacturing the same to form a silicon film for separating the color on the photodiode so that the color separation is performed in front of the photodiode to improve the light sensitivity.

According to an embodiment of the present invention, a CMOS image sensor includes a device isolation layer formed on a semiconductor substrate to define an active region and a field region, and a plurality of red and green regions and blue regions formed in the active region. An interlayer insulating film formed on a photodiode and a semiconductor substrate including the plurality of photodiodes, a plurality of metal wirings formed on the interlayer insulating film, a plurality of metal interlayer insulating films, and a top metal interlayer of the plurality of metal interlayer insulating films A final metal interconnection formed on the insulating film, a planarization layer formed on the final metal interconnection, and a microlens formed on the planarization layer, and formed between an upper portion of the red region and an upper portion of the green region and the final metal interconnection layer, It further comprises a silicon film for separating the incident light Eojinda.

In this case, the silicon film on the green region is formed to have a thickness of 0.2 μm to 0.8 μm in the interlayer insulating film.

In addition, the silicon layer on the red region is formed in the interlayer insulating film 0.2㎛ to 0.8㎛ thickness, the photodiode of the red region is deeper than the doping depth of the photodiode of the green region and the photodiode of the blue region, for example The photodiode in the red region is doped from the substrate surface to a depth of 0.4 μm to 1.0 μm.

Alternatively, the silicon film formed on the red region is formed to have a thickness of 1.2 μm to 1.8 μm through the interlayer insulating film and the multi-layered metal interlayer insulating film, or the silicon film formed on the red region is formed in the interlayer insulating film and the multiple metal interlayer insulating films, respectively. It can be made of a multi-layer structure.

According to another aspect of the present invention, a method of manufacturing a CMOS image sensor includes: forming a photodiode in each of red, green, and blue regions of a semiconductor substrate separated by an isolation layer; and the plurality of photodiodes Forming an interlayer insulating film on the entire surface of the semiconductor substrate; forming a multilayer metal wiring and a multilayer metal interlayer insulating film on the interlayer insulating film; and forming a final metal wiring on the uppermost metal interlayer insulating film of the multilayer metal interlayer insulating film. And forming a planarization film and a micro lens on the final metal wire, wherein the silicon film further separates light incident from the micro lens between the red area and the green area and the final metal wire layer. Form.

In the forming of the photodiode, the photodiode of the red region is formed deeper than the photodiode doping depth of the green region and the blue region. In this case, the red region photodiode may be formed to a depth of 0.4 ~ 1.0㎛ from the substrate surface.

The silicon film may be formed in the interlayer insulating film over the red region and the interlayer insulating film over the green region, or in the green region, and in the red region, and may pass through the interlayer insulating film and the multilayer metal interlayer insulating film in the red region. Can be.

Alternatively, the silicon film may be formed in the interlayer insulating film in the green region, and in the red region in the interlayer insulating film and the multilayer metal interlayer insulating film, respectively, to form a multilayer structure.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like reference numerals designate like parts throughout the specification.

First, a method of manufacturing a CMOS image sensor according to a first embodiment of the present invention will be described in detail with reference to FIGS. 2A to 2D.

2A to 2D are cross-sectional views sequentially illustrating a method of manufacturing a CMOS image sensor according to a first exemplary embodiment of the present invention.

Referring to FIG. 2A, a p-type epitaxial layer 12 having a lower concentration than that of the semiconductor substrate is formed on a high concentration p-type semiconductor substrate 11. The reason for using the low concentration epitaxial layer 13 is that the depth of the depletion layer of the photodiode can be increased to improve the characteristics, and the high concentration substrate can prevent cross talk between unit pixels. Because there is.

Next, a device isolation layer 13 defining an active region and a field region is formed in the p-type epitaxial layer 12 to define a red region R, a green region G, and a blue region B.

Next, the photodiode 14 is formed in a predetermined region among the defined active regions. The photodiode is generally composed of an n-type ion implantation region (typically labeled as 'Deep N region') formed deep inside a semiconductor substrate and a p-type ion implantation region (usually designated as 'P ⁺ region') formed thereon. In addition to the p-type epitaxial layer 12, a p / n / p structure photodiode structure is often used.

Here, the description of the various transistors constituting the unit pixel is omitted.

Referring to FIG. 2B, an interlayer insulating layer 15 is formed on the semiconductor substrate 11 on which the photodiode 14 and related elements are formed.

Subsequently, a portion of the interlayer insulating layer 15 corresponding to the green photodiode 14b is etched through a predetermined photo and etching process to form a trench (not shown).

Then, the first silicon film 16 is formed in the trench (not shown) to a thickness of about 0.2 μm to 0.8 μm, preferably about 0.5 μm. In this case, the first silicon film 16 is formed to reduce the probability of incident light incident on the green region scattering or penetrating into adjacent unit pixels, thereby increasing the final light integration efficiency.

Referring to FIG. 2C, the first metal interconnection 17, the first metal interlayer insulation layer 18, the second metal interconnection 19, and the first metal interconnection layer 15 may be formed on the interlayer insulation layer 15 including the first silicon layer 16. 2 a metal interlayer insulating film 20 is formed.

Referring to FIG. 2D, the second metal interlayer insulating layer 20, the first interlayer insulating layer 18, and the interlayer insulating layer 15 corresponding to the red photodiode 14a are sequentially etched by performing a predetermined photo and etching process. To form a trench (not shown).

Subsequently, the second silicon film 21 is formed in the trench (not shown) to a thickness of about 1.2 μm to 1.8 μm, preferably about 1.5 μm. In this case, the second silicon film 21 is also formed to reduce the probability that incident light scatters or penetrates into adjacent unit pixels like the first silicon film 16.

Next, a third metal wiring 22 is formed on the resultant product on which the second silicon film 21 is formed, and the third metal wiring 22 is embedded with the third metal interlayer insulating film 23 to form a final metal wiring 24. .

Thereafter, the final metal wiring 24 is formed with an over coating layer (OCL) using the planarization layer 25, and finally the microlens 26 is formed.

As described above, according to the first exemplary embodiment of the present invention, a silicon film having a different thickness on the upper portion corresponding to the red photodiode region and the upper portion corresponding to the green photodiode region is obtained by using a characteristic in which absorption and transmittance are different according to the wavelength of light. After forming, by condensing incident light with a photodiode, the distance between the photodiode and the microlens can be reduced by not implementing a color filter.

As a result, color scattering or dispersion of light is suppressed in front of the photodiode, thereby increasing light collection efficiency and preventing light from penetrating into adjacent unit pixels, thereby preventing noise or cross talk. You can do it.

3A to 3E are cross-sectional views sequentially illustrating a method of manufacturing a CMOS image sensor according to a second exemplary embodiment of the present invention, all of which are the same as the first exemplary embodiment, but are formed in the first exemplary embodiment. Since the second trench is deep, that is, because the second silicon film is formed too thick, the second silicon film is formed by dividing the second silicon film into a multilayer silicon layer.

Referring to FIG. 3A, a low concentration p-type epi layer 12 is formed on the semiconductor substrate 11.

Next, an isolation layer 13 defining an active region and a field region is formed in the p-type epitaxial layer 12 to define a red region (R), a green region (G), and a blue region (B). Photodiodes 14a, 14b, and 14c are formed in predetermined regions. Here, the description of the various transistors constituting the unit pixel is omitted.

Referring to FIG. 3B, an interlayer insulating layer 15 is formed on the semiconductor substrate 11 on which the photodiodes 14a, 14b, 14c and related elements are formed.

Subsequently, a portion of the interlayer insulating layer 15 corresponding to the red photodiode 14a and the green photodiode 14b is etched through a predetermined photo and etching process to form a trench, and then the first silicon layer 31a, 31b) is formed in a thickness of 0.2 to 0.8 mu m, preferably about 0.5 mu m. In this case, the first silicon layers 31a and 31b are formed to reduce the probability of incident light incident on the red region or the green region being scattered or penetrating into adjacent unit pixels, thereby increasing final photo-integration efficiency. do.

Referring to FIG. 3C, the first metal interconnection 17 is formed on the interlayer insulating layer 15 including the first silicon layers 31a and 31b, and the first interlayer insulating layer 18 is formed on the resultant.

Then, a trench is formed in the first metal interlayer insulating film 18 corresponding to the red photodiode 14a, and a second silicon film 32 is formed in the trench to a thickness of about 0.5 μm.

Next, a second metal wiring 19 and a second metal interlayer insulating film 20 are formed on the first interlayer insulating film 18 including the second silicon film 32.

Referring to FIG. 3D, a predetermined photo and etching process may be performed to etch the second metal interlayer insulating layer 20 corresponding to the red photodiode 14a to form a trench, and then form a third silicon layer 33 in the trench. It is formed to a thickness of about 0.2㎛ to 0.8㎛ preferably 0.5㎛.

Referring to FIG. 3E, a third metal wire 22 is formed on the second metal interlayer insulating film 20 on which the third silicon film 33 is formed, and is finally embedded with the third metal interlayer insulating film 23. The metal wiring 24 is formed.

Thereafter, the final metal wiring 24 is formed with an over coating layer (OCL) using the planarization layer 25, and finally the microlens 26 is formed.

In the second embodiment of the present invention, the sum of the thicknesses of the first silicon film 31a, the second silicon film 32, and the third silicon film 33 on the red photodiode 14a is 1.2 μm to 1.8 μm. Make it accurate.

4A to 4D are cross-sectional views sequentially illustrating a method of manufacturing a CMOS image sensor according to a third exemplary embodiment of the present invention.

Referring to FIG. 4A, a low concentration p-type epi layer 12 is formed on the semiconductor substrate 11.

Next, an isolation layer 13 defining an active region and a field region is formed in the p-type epitaxial layer 12 to define a red region (R), a green region (G), and a blue region (B). Photodiodes 14a ', 14b and 14c are formed in predetermined regions.

What is important when forming the photodiodes 14a ', 14b and 14c is that the doping depth of the red photodiode 14a' is formed deeper than the green and blue photodiodes, specifically from the substrate surface. It is preferable to form to 0.4 micrometer-1.0 micrometer in depth.

Referring to FIG. 4B, an interlayer insulating layer 15 is formed on the semiconductor substrate 11 on which the photodiode 14 and related elements are formed.

Subsequently, a portion of the interlayer insulating layer 15 corresponding to the red photodiode 14a and the green photodiode 14b is etched through a predetermined photo and etching process to form a trench, and then silicon films 41a and 41b are formed in the trench. It is formed to a thickness of about 0.2㎛ to 0.8㎛ preferably 0.5㎛. In this case, the silicon films 41a and 41b are formed to reduce the probability of incident light incident on the red region or the green region being scattered or penetrating into adjacent unit pixels, thereby increasing final photo-integration efficiency.

Referring to FIG. 4C, the first metal interconnection 17, the first metal interlayer insulation layer 18, the second metal interconnection 19, and the second metal layer may be disposed on the interlayer insulation layer 15 including the silicon layers 41a and 41b. The metal interlayer insulating film 20 is sequentially formed.

Referring to FIG. 4D, the third metal interconnection 22 is formed on the second metal interlayer insulating layer 20, and the final metal interconnection 24 is formed after filling the third metal interconnection 22 with the third metal interlayer insulation layer 23.

Thereafter, the final metal wiring 24 is formed with an over coating layer (OCL) using the planarization layer 25, and finally the microlens 26 is formed.

Although the preferred embodiments of the present invention have been described in detail above, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Accordingly, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

 As described above, according to the present invention, using a difference in depth and absorption rate through which silicon transmits according to the wavelength of light, a silicon film that separates color near the photodiode with a color filter object has a different thickness for each region. Therefore, by not forming a color filter for color separation, the distance between the microlens and the photodiode is reduced, thereby preventing light scattering or scattering and preventing crosstalk to adjacent photodiodes, thereby improving reliability of the device. have.

In addition, the present invention has the advantage that the light sensitivity can be improved by performing the color separation in front of the photodiode.

Claims (17)

An isolation layer formed on the semiconductor substrate to define an active region and a field region; A plurality of photodiodes formed in the red, green and blue regions formed in the active region; An interlayer insulating film formed on the semiconductor substrate including the plurality of photodiodes, A plurality of metal wirings and a plurality of metal interlayer insulating films formed on the interlayer insulating film; A final metal wiring formed on an uppermost metal interlayer insulating film of said plurality of metal interlayer insulating films; A planarization film formed on the final metal wiring; And Including a microlens formed on the planarization film, And a silicon film formed between the red region and the green region and the final metal wiring layer to separate light incident from the microlens. The method of claim 1, The silicon film on the green region, the CMOS image sensor, characterized in that formed in the interlayer insulating film having a thickness of 0.2 ㎛ to 0.8 ㎛. The method of claim 1, The silicon film on the red region, the CMOS image sensor, characterized in that formed in the interlayer insulating film thickness of 0.2㎛ 0.8㎛. The method of claim 3, And the photodiode of the red region is doped more deeply than the doping depths of the photodiode of the green region and the photodiode of the blue region. The method of claim 4, wherein And the photodiode in the red region is doped from the substrate surface to a depth of 0.4 ㎛ to 1.0 ㎛. The method of claim 1, The silicon film formed on the red region is a CMOS image sensor, characterized in that formed to a thickness of 1.2㎛ to 1.8㎛. The method of claim 1, The silicon film formed on the red region, the CMOS image sensor, characterized in that the multi-layer structure formed in each of the interlayer insulating film and a plurality of metal interlayer insulating film. The method of claim 7, wherein The single silicon film of the multilayer silicon film, the CMOS image sensor, characterized in that formed to a thickness of 0.2㎛ to 0.8㎛. The method of claim 7, wherein The silicon film of the multilayer structure, the sum of the thickness is formed from 1.2㎛ to 1.8㎛ CMOS sensor. In the method of manufacturing the CMOS image sensor, Forming a photodiode in each of red, green, and blue regions of the semiconductor substrate separated by the device isolation layer; Forming an interlayer insulating film on an entire surface of the semiconductor substrate including the plurality of photodiodes; Forming a multilayer metal wiring and a multilayer metal interlayer insulating film on the interlayer insulating film; Forming a final metal wiring on an uppermost metal interlayer insulating film of the multilayer metal interlayer insulating films; And Forming a planarization film and a micro lens on the final metal wiring; And forming a silicon film separating the light incident from the microlens between the red region and the green region and the final metal wiring layer. The method of claim 10, Forming the photodiode, And forming a photodiode of the red region deeper than a photodiode doping depth of the green region and the blue region. The method of claim 11, The red region photodiode is formed in a 0.4 μm to 1.0 μm depth from the substrate surface. The method of claim 12, The silicon film is formed on the interlayer insulating film over the red region and the interlayer insulating film over the green region. The method of claim 10, The silicon film is formed on the interlayer insulating film in the green region, and the red region is formed to pass through the interlayer insulating film and the multi-layer metal interlayer insulating film. The method of claim 14, The silicon film thickness of the upper portion of the red region photodiode is formed in a thickness of 1.2㎛ 1.8㎛, manufacturing method of the CMOS image sensor. The method of claim 10, The silicon film, In the green region is formed on the interlayer insulating film, And forming a multi-layered structure in the red region, respectively, on the interlayer insulating film and the multi-layered metal interlayer insulating film. The method of claim 15, The silicon film of the multi-layer structure on the red region is formed so that the sum of the thicknesses is 1.2 µm to 1.8 µm.

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