KR101024765B1 - Image Sensor and Method for Manufacturing Thereof - Google Patents

Abstract

An image sensor according to an embodiment includes a semiconductor substrate on which a photodiode is formed; A metal wiring and an interlayer insulating layer formed on the semiconductor substrate; A color filter formed on the interlayer insulating layer so as to correspond to the photodiode and having a gap region formed therebetween; A micro lens formed on the color filter to expose the gap area; An auxiliary lens formed on the micro lens; And a trench formed between the auxiliary lenses to expose the gap region, and a light absorption pattern formed in the trench.

Image Sensor, Photodiode, Micro Lens

Description

Image Sensor and Method for Manufacturing Thereof}

Embodiments relate to an image sensor and a manufacturing method thereof.

An image sensor is a semiconductor device that converts an optical image into an electrical signal, and is largely a charge coupled device (CCD) and a CMOS (Complementary Metal Oxide Silicon) image sensor. Sensor) (CIS).

The CMOS image sensor implements an image by sequentially detecting an electrical signal of each unit pixel in a switching method of 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.

Such microlenses advance the photosensitive organic material in the order of exposure, development, and reflow to form a hemispherical shape.

Then, the light incident between the gaps of the microlenses is straight as it is not collected by the photodiode, which causes a decrease in the light sensitivity of the image sensor.

In addition, there is a problem that noise and crosstalk are generated by passing uncondensed light between the gaps of the microlenses and detecting the unit pixels disposed on the pixel array substrate.

The gap is generated because the wide space generated between the lens and the lens during the patterning process of the micro lens cannot be reduced in the reflow process.

Of course, the gap may be reduced during the reflow process, but excessive reflow may cause the lens and the lens to stick to each other, resulting in a bridge and merge phenomenon, which may cause a defect of the image sensor.

The embodiment provides an image sensor and a method of manufacturing the same, by forming an anti-reflection film between the gaps of the microlenses to suppress interference of incident light to improve light sensitivity.

An image sensor according to an embodiment includes a semiconductor substrate on which a photodiode is formed; A metal wiring and an interlayer insulating layer formed on the semiconductor substrate; A color filter formed on the interlayer insulating layer so as to correspond to the photodiode and having a gap region formed therebetween; A micro lens formed on the color filter to expose the gap area; An auxiliary lens formed on the micro lens; And a trench formed between the auxiliary lenses to expose the gap region, and a light absorption pattern formed in the trench.

In another aspect, a method of manufacturing an image sensor includes: forming a photodiode on a semiconductor substrate; Forming a metal wiring and an interlayer insulating layer on the semiconductor substrate; Forming a color filter having a gap region formed on the interlayer insulating layer so as to correspond to the photodiode and spaced apart from each other; Forming a micro lens on the color filter to expose the gap area; Forming a lens layer on the microlens and the gap region; and forming a light absorption pattern between the microlenses so as to pass through the lens layer corresponding to the gap region.

According to the image sensor and the manufacturing method thereof according to the embodiment, a light absorption pattern is formed between the microlenses to prevent incident light having an inclination angle from entering the neighboring microlenses, thereby preventing crosstalk.

In addition, since the auxiliary lens is formed on the upper portion of the microlens to condense light in duplicate, the image sensitivity may be improved.

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

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

6 is a cross-sectional view illustrating an image sensor according to an embodiment.

An image sensor according to an embodiment includes a semiconductor substrate 10 on which a plurality of photodiodes 20 are formed; A metal wiring 50 and an interlayer insulating layer 40 formed on the semiconductor substrate 10; A color filter 70 formed on the interlayer insulating layer 40 so as to correspond to the photodiode 20 and having a gap region D formed therebetween; A micro lens 80 formed on the color filter 70 to expose the gap region D; An auxiliary lens 95 formed on the micro lens 80; A trench 97 formed between the auxiliary lens 95 to expose the gap region D, and a light absorption pattern 105 formed in the trench 97.

For example, the light absorption pattern 105 may be formed of an antireflection material. Accordingly, crosstalk can be prevented because the light having the inclination angle can absorb the light traveling to the neighboring pixel instead of the corresponding pixel.

The micro lens 80 and the auxiliary lens 95 may be formed of a low temperature oxide film. For example, the microlens 80 may be formed of SiON or SiOC, and the auxiliary lens 95 may be formed of SiO2. Since the refractive index of the material forming the microlens 80 has a higher refractive index than the auxiliary lens 95, the fill factor of the photodiode may be improved.

Unexplained reference numerals among the reference numerals of FIG. 6 will be described in the following manufacturing method.

Hereinafter, a manufacturing method of an image sensor according to an embodiment will be described with reference to FIGS. 1 to 7.

Referring to FIG. 1, a photosensitive device including a photodiode 20 and a CMOS circuit (not shown) is formed on a semiconductor substrate 10.

An isolation layer 20 defining an active region and a field region is formed on the semiconductor substrate 10, and a photodiode 20 for generating photocharges by receiving light in the active region of the semiconductor substrate 10. And a CMOS circuit (not shown) connected to the photodiode 20 to convert the received photocharges into an electrical signal, may be formed for each unit pixel.

After the related devices including the photodiode 20 are formed, a metal wiring 50 and an interlayer insulating layer 40 are formed on the semiconductor substrate 10.

The metal wires M1, M2, and M3 50 may be formed of a plurality of layers to connect a power line, a signal line, an optical sensing element, and a peripheral circuit. That is, the interlayer insulating layer 40 may be formed of a plurality of layers, and a plurality of the metal wires 50 passing through the interlayer insulating layer 40 may also be formed to be in electrical contact with each other.

The metal wire 50 is intentionally laid out so as not to block light incident on the photodiode 20.

For example, the interlayer insulating layer 40 may be formed of an oxide film material, and the metal wire 50 may be formed of various conductive materials including metal, alloy, or silicide, that is, aluminum, copper, cobalt, or tungsten. Can be.

Next, a protective layer 60 is formed on the interlayer insulating layer 40. The protective layer 60 is formed on the interlayer insulating layer 40 including the final metal wiring 50 to protect the device from moisture or scratches. For example, the protective layer 60 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. Of course, the protective layer 60 may not be formed.

Next, the color filter 70 is formed on the protective layer 60. The color filter 70 is formed for each unit pixel to separate colors from incident light. The color filter 70 represents a different color for each unit pixel, and may be formed of three colors of red (R), green (G), and blue (B).

The color filter 70 forms a color filter material (not shown) including a photosensitive material and a pigment or a photosensitive material and a dye on the semiconductor substrate 10 through a spin coating process or the like. Subsequently, the color filter material may be exposed and developed using a pattern mask (not shown) to form a color filter 70 on the semiconductor substrate 10. That is, the green and blue color filters 70 may be formed after the color filters 70 corresponding to red are formed. In addition, the color filter 70 may be formed to have a gap region D to be spaced apart from the neighboring color filter 70. For example, the gap region D may be formed to have a width corresponding to the metal wiring 50. Therefore, the surface of the protective layer 60 corresponding to the metal wiring 50 may be exposed by the gap region D.

Referring to FIG. 2, a microlens 80 is formed on the color filter 70. The microlens 80 may be formed one by one for each color filter 70 to condense light to the photodiode 20 formed at a lower portion thereof. In addition, since the microlens 80 is formed to correspond to the color filter 70, the protective layer 60 exposed by the gap region D may be exposed as it is even when the microlens 80 is formed. have.

The micro lens 80 may be formed of a low temperature oxide layer including SiON or SiOC. The refractive index of the micro lens 80 may be 1.5 to 2.2.

Although not shown, in order to form the micro lens 80, an oxide layer is formed on the color filter 70 by a low temperature process. After forming a hemispherical photoresist pattern on the oxide layer, the oxide layer may be etched using the photoresist pattern as an etching mask to form the hemispherical microlens 80.

Referring to FIG. 3, a lens layer 90 is formed on the semiconductor substrate 10 including the gap region D and the micro lens 80. For example, the lens layer 90 may be formed of a low temperature oxide film such as SiO ₂ . For example, the refractive index of the lens layer 90 may be 1.4 to 1.45.

The lens layer 90 may be formed by depositing an oxide layer on the microlens 80 and the gap region D at a low temperature, and then performing a CMP process. Thus, the lens layer 90 may have a flattened surface.

Referring to FIG. 4, a mask pattern 200 is formed on the lens layer 90. The mask pattern 200 may be formed by coating and patterning a photoresist layer on the lens layer 90. The mask pattern 200 may be formed on the lens layer 90 corresponding to the micro lens 80 to expose a surface of the lens layer 90 corresponding to the gap region D.

Next, the lens layer 90 is etched using the mask pattern 200 as an etch mask to form an auxiliary lens 95 on the microlens 80. That is, when the etching process is performed by the mask pattern 200, the lens layer 90 corresponding to the gap region D is selectively etched so that the auxiliary lens 95 is formed on the microlens 80. A trench 97 is formed between the auxiliary lenses 95 to expose the gap region D.

The microlens 80 and the auxiliary lens 95 may be separated for each unit pixel by the trench 97. In addition, an auxiliary lens 95 is formed on the microlens 80 to condense light primarily by the auxiliary lens 95, and then, by the microlens 80 under the auxiliary lens 95, the second lens 95 is formed. By condensing light with a car, the light condensing ratio of the photodiode 20 may be improved.

Subsequently, the mask pattern 200 may be removed by ashing and cleaning.

Referring to FIG. 5, a light absorption film 100 is formed on a semiconductor substrate 10 including the trench 97 and the auxiliary lens 95. The light absorption film 100 may be formed to completely fill the trench 97.

For example, the light absorption film 100 may be formed of an organic anti-reflection layer (BARC). That is, the light absorption film 100 may be formed by applying an organic material that is easy to absorb light in the wavelength range of light.

Referring to FIG. 6, a light absorption pattern 105 is formed in the trench 97. The light absorption pattern 105 may be formed by performing an etch-back process on the light absorption layer 100 until the upper surface of the auxiliary lens 95 is exposed. Then, the light absorption pattern 105 may be formed only in the trench 97.

The light absorption pattern 105 may be formed inside the trench 97 between the micro lenses 80 to prevent incident light having an inclination angle from incident to adjacent unit pixels, thereby preventing cross talk. That is, since the light absorption pattern 105 is formed of the anti-reflection film material and the incident light having the inclination angle proceeds to the adjacent pixels, the light absorption pattern 105 is absorbed by the light absorption pattern 105, thereby suppressing cross talk.

In addition, a recess 107 is formed on the light absorption pattern 105 as shown in FIG. 7. The recess groove 107 may be formed by a recess process for selectively etching only the light absorption pattern 105. By the recess process, all residues of the light absorption film 100 remaining on the auxiliary lens 95 may be removed to improve image characteristics of the image sensor.

According to the method of manufacturing the image sensor according to the embodiment, the auxiliary lens 95 is formed on the micro lens 80 to improve the light condensation rate of the photodiode 20. That is, since the auxiliary lens 95 has a larger refractive index than the atmosphere, light incident at an inclination angle may be first collected into the microlens 80. In addition, since the light collected by the microlens 80 is first collected by the photodiode 20 by the high refractive index of the microlens 80, image characteristics may be improved by improving the fill factor.

In addition, the light absorption pattern 105 is formed between the micro lens 80, the light absorption pattern 105 when the incident light having a large inclination angle proceeds to the lens of the adjacent unit pixel instead of the corresponding unit pixel. By absorbing this, the sensitivity of the image sensor can be optimized by suppressing cross talk, that is, interference.

The above-described embodiments are not limited to the above-described embodiments and drawings, and it is common in the technical field to which the present embodiments belong that various changes, modifications, and changes can be made without departing from the technical spirit of the present embodiments. It will be apparent to those who have

1 to 7 are cross-sectional views illustrating a manufacturing process of an image sensor according to an embodiment.

Claims (10)

delete delete delete delete Forming a photodiode on the semiconductor substrate; Forming a metal wiring and an interlayer insulating layer on the semiconductor substrate; Forming a color filter having a gap region formed on the interlayer insulating layer so as to correspond to the photodiode and spaced apart from each other; Forming a micro lens on the color filter to expose the gap area; Forming a lens layer on the micro lens and the gap region: and And forming a light absorption pattern between the micro lenses to penetrate the lens layer corresponding to the gap region. The method of claim 5, Forming the lens layer, Forming a low temperature oxide film on the micro lens; And The manufacturing method of the image sensor comprising the step of performing a CMP process for the low-temperature oxide film. The method of claim 5, Forming the light absorption pattern, Forming a photoresist pattern on the lens layer to correspond to the micro lens; Forming a trench to expose the gap region by etching the lens layer using the photoresist pattern as an etching mask; Forming a light absorption layer to gap-fill the inside of the trench; And And forming a light absorption pattern only in the trench by performing an etch back process on the light absorption layer. The method of claim 7, wherein And further performing a recess process so that the light absorption layer does not remain in the lens layer. The method of claim 5, The light absorption pattern is a manufacturing method of the image sensor, characterized in that formed of an anti-reflection material. The method of claim 5, The micro lens is a method of manufacturing an image sensor, characterized in that formed of a low temperature oxide film.

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