KR20100067982A

KR20100067982A - Image sensor and method for fabricating the same

Info

Publication number: KR20100067982A
Application number: KR1020080126611A
Authority: KR
Inventors: 박승룡
Original assignee: 주식회사 동부하이텍
Priority date: 2008-12-12
Filing date: 2008-12-12
Publication date: 2010-06-22

Abstract

Embodiments relate to an image sensor and a method of manufacturing the same. The image sensor according to the embodiment includes a substrate on which a pixel array is formed and a prism array in which prisms having an inclined angle increase in a radially outward direction from a central region of the substrate are disposed corresponding to each pixel. In an embodiment, the prism array is disposed under the color filter array to change the path of the light passing through the prism array so that light may be incident perpendicularly to all pixels, thereby eliminating the difficulty of wiring design and photodiode throughout the chip. By allowing light to be incident at a uniform angle, it is possible to improve the uniformity of light sensitivity, thereby improving the reliability of the image sensor.

Description

Image sensor and manufacturing method thereof {IMAGE SENSOR AND METHOD FOR FABRICATING THE SAME}

Embodiments relate to an image sensor and a method of manufacturing the same.

Recently, with the development of semiconductor manufacturing technology, semiconductor devices for converting images into electric signals have been developed. The image sensor device is a representative semiconductor device for electrically converting an image. Representative image sensor devices include charge coupled device (CCD) devices and CMOS image devices. The CCD device includes a plurality of MOS capacitors, which are operated by moving carriers generated by light. On the other hand, the CMOS image element includes a plurality of unit pixels and CMOS logic circuit for controlling the output signal of the unit pixel.

After the fabrication process is completed, the image sensor device undergoes a packaging process and the like, and an external lens is attached to the upper portion thereof.

In a conventional image sensor, light is incident on an image sensor pixel from an external lens.

The light incident from the external lens does not have any problem in forming an image on the center of the pixel of the image sensor, but the amount of light incident to the photodiode through the microlens decreases toward the pixel edge of the image sensor.

When the amount of light incident on the unit pixel is changed, the number of generated electrons is also changed so that the original image is incident on the color and edge of the image incident on the center of the image sensor element even though the original image has the same color. The color of the image is displayed in a different color. This phenomenon causes serious problems in the reliability of the image sensor.

The embodiment provides an image sensor and a method of manufacturing the same, by arranging a prism array under a color filter array to change a path of light passing through the prism array so that light is incident perpendicularly to all pixels.

The image sensor according to the embodiment includes a substrate on which a pixel array is formed and a prism array in which prisms having an inclined angle increase in a radially outward direction from a central region of the substrate are disposed corresponding to each pixel.

According to an embodiment, there is provided a method of manufacturing an image sensor, including forming a pixel array on a substrate, and corresponding to each pixel on the substrate, prisms in which the inclination angles increase in a radially outward direction from the center region of the substrate are arranged. Forming an array.

An image sensor according to an embodiment includes a semiconductor substrate including a light receiving element in each pixel;

And a metal wiring layer formed on the semiconductor substrate, a prism array formed on the metal wiring layer and having a prism corresponding to each pixel, and a color filter array formed on the prism array.

In the manufacturing method of the image sensor according to the embodiment, the step of forming a light receiving element in each pixel on the semiconductor substrate, forming a metal wiring layer on the semiconductor substrate, the prism is disposed corresponding to each pixel on the metal wiring layer Forming an array of prisms, and forming an array of color filters on the prisms array.

In an embodiment, the prism array is disposed under the color filter array to change the path of the light passing through the prism array so that light may be incident perpendicularly to all pixels, thereby eliminating the difficulty of wiring design and photodiode throughout the chip. By allowing light to be incident at a uniform angle, it is possible to improve the uniformity of light sensitivity, thereby improving the reliability of the image sensor.

In the image sensor according to the embodiment, in forming the micro-prism array corresponding to the unit pixels, the angle of the micro-prism is adjusted from the center of the substrate to the outside to make the incident angle of the light constant throughout the pixel design of the image sensor There is an effect that can be simplified.

In the description of an embodiment, where each layer (film), region, pattern, or structure is described as being formed "on" or "under" a substrate, each layer (film), region, pad, or pattern, The meaning may be interpreted as when each layer (film), region, pad, pattern or structures is formed in direct contact with the substrate, each layer (film), region, pad or patterns, and other layers (film), It may also be interpreted that another region, another pad, another pattern, or another structure is additionally formed therebetween. Therefore, the meaning should be determined by the technical spirit of the invention.

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

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

The circuit layer 20 is formed on the semiconductor substrate 10.

The metal wiring layer 30 is formed on the circuit layer 20.

A protective film is formed on the metal wiring layer 30.

The prism array 40 is formed on the passivation layer.

The planarization layer 45 is formed on the prism array 40.

The color filter array 50 is formed on the planarization layer 45.

The micro lens array 60 is formed on the color filter array 50.

An isolation layer 11 and a light receiving element 12 may be formed on the semiconductor substrate 10.

The light receiving element 12 may be a photo diode.

The circuit layer 20 may be formed of a circuit including a transistor.

The metallization layer 30 may include a wiring 31 connected to the circuit. The metal wiring layer 30 may be formed to include an interlayer insulating layer 33.

The passivation layer may include at least one of an organic layer and an inorganic layer.

The planarization layer 45 may include an organic layer.

The color filter array 50 includes a red color filter, a green color filter, and a blue color filter corresponding to each pixel.

The micro lens array 60 may be formed of lenses in which an upper surface thereof is convex in a dome shape corresponding to each pixel.

According to an embodiment, the prism array 40 includes prisms 41 that change the light path corresponding to each pixel. The prism array 40 has a different inclination angle of the prism 41 according to the incident angle of light incident on each prism 41.

The light exiting the prism array 40 may be incident on the light receiving element 12 in a direction perpendicular to the semiconductor substrate 10.

Although the angles of the light incident on the prism array 40 are different, the light emitted through the prism array 40 is emitted in the same direction in a direction perpendicular to the semiconductor substrate 10.

The lower surface of each prism 41 in the prism array 40 has the same plane as the upper surface of the passivation layer, and the degree of light refraction of the prism 41 depends on the inclination angle and inclination direction of the upper surface having the inclined surface with respect to the plane. Can be adjusted.

The inclination angle of the inclined surface may increase as the prism array 40 moves from the center region to the outer region of the pixel array region.

The inclination angle of the inclined surface may increase as the prism array 40 moves radially outward from the center of the pixel array region.

The prism array 40 may have an inclined direction of the inclined surface of each prism 41 in a radially outward direction at the center of the pixel array region.

As such, the prism 41 of each prism array 40 may be formed using a gray scale mask 70.

The gray scale mask 70 is a mask that can adjust the amount of light irradiated to the photosensitive film according to position, and the photoresist pattern exposed and developed by the gray scale mask 70 may be formed such that its upper surface has an inclined surface. Can be.

That is, when the light transmittance is continuously changed in one mask pattern 71 corresponding to each pixel, the thickness of the photoresist exposed to light passing through the mask pattern 71 is continuously changed according to the exposure amount. Therefore, the upper surface of the photoresist pattern corresponding to the mask pattern 71 has an inclined surface.

2 to 5 are cross-sectional views illustrating a manufacturing process of an image sensor according to an embodiment.

2 to 5 illustrate the pixels of the center region, the pixels of the left outer region, and the pixels of the right outer region.

Referring to FIG. 2, as shown in FIG. 1, the circuit layer 20 is formed on the semiconductor substrate 10, the metal wiring layer 30 is formed on the circuit layer 20, and then the metal wiring layer ( A photosensitive film 40a is formed on 30.

Before forming the photosensitive film 40a, a protective film made of an organic film or an inorganic film may be further formed on the metal wiring layer 30.

The gray scale mask 70 is disposed on the photosensitive film 40a.

Each mask pattern 70a of the gray scale mask 70 is continuously changed in gray scale to have a desired inclination angle.

If the photoresist film 40a is a positive photoresist film, the positive photoresist film has a characteristic of being removed by a developer as more light is received.

Therefore, in the positive photosensitive film pattern having the inclined surface, the exposure amount decreases from the lower side to the higher side.

If the photosensitive film 40a is a negative photosensitive film, since it has the opposite characteristics, it will be designed in consideration of this.

In addition, the center region of the pixel array region may not be formed since light is incident vertically into the light receiving element so that the prism 41 for refracting the light is not necessary.

In this case, as long as the photosensitive film is a positive photosensitive film, the portion where the prism is not formed may be 100% of the exposure amount.

When light does not need to be refracted by the light incident vertically to the light receiving element, it may be formed as a flat surface parallel to the lower surface without placing an inclined surface of the upper surface of the prism 41.

As described above, the gray scale mask 70 may be used to form the prism array 40 as shown in FIG. 3. The inclination direction and the inclination angle of the inclined surface of each prism 41 may be adjusted to correspond to each pixel by using the gray scale mask 70.

As shown in FIG. 4, a planarization film 45 is formed on the prism array 40.

Subsequently, as illustrated in FIG. 5, the color filter array 50 may be formed on the planarization layer 45, and the micro lens array 60 may be formed on the color filter array 50.

The color filter array 50 may include a blue color filter, a red color filter, and a green color filter.

The refractive index of the photosensitive film 40a for forming the singer prism array 40 may be 1.5 to 1.6, and the refractive index of the planarization film 45 and the interlayer insulating film 33 of the metal wiring layer 30 may be the prism array 40. For example, it may be less than the refractive index of the photosensitive film 40a for forming.

6 and 7 are a perspective view and a schematic enlarged cross-sectional view showing an image sensor according to an embodiment.

6 shows a prism array 40 formed in one die on a wafer. FIG. 7 shows a prism array 40 having a tilt angle that varies from the center direction to the outward direction in the wafer 90.

Referring to FIG. 6, it can be seen that the inclination direction of the prism array 40 varies from the center to the radially outward direction in the pixel array region.

That is, not only the inclination directions of the left and right outer directions in the pixel array region may be changed, but also the inclination directions of the inclined surfaces of the prism may vary in the up, down, and diagonal directions.

7, it can be seen that the inclination angle of the inclined plane of the prism 41 of the prism array increases from the center to the outer side in the pixel array region.

Each prism 41 has an inclined surface having a predetermined inclination angle with respect to the lower surface, and each inclination angle becomes larger from the center to the outer direction (θ1> θ2> θ3> θ4> θ5) and becomes smaller toward the center. Lose.

This is because light incident on the inclined surface of each prism 41 should pass in the direction perpendicular to the lower surface of the prism 41 after passing through the prism 41.

In the embodiment, the prism array 40 is disposed under the color filter array 50 to change the path of the light passing through the prism array 40 so that light can be incident perpendicularly to all pixels, thereby making it difficult to design the wiring. By solving the problem and allowing light to be incident at a uniform angle to the photodiode from the entire chip, it is possible to improve the uniformity of the light sensitivity, thereby improving the reliability of the image sensor.

In forming the micro-prism array 60 corresponding to the unit pixels, the image sensor according to the embodiment adjusts the angle of the micro-prism from the center of the substrate to the outside to make the incident angle of light constant throughout the pixels. The effect is to simplify the design of the sensor.

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.

6 is a perspective view illustrating an image sensor according to an exemplary embodiment.

7 is a schematic enlarged cross-sectional view showing a portion of an image sensor according to an embodiment.

Claims

A substrate on which a pixel array is formed; And

And a prism array formed on a substrate, the prism array having an inclination angle that increases in a radially outward direction from a central region of the substrate to correspond to each pixel.

The method of claim 1,

And the inclined surface of the prism has an inclined direction in a radially outward direction from the center of the pixel array.

The method of claim 1,

And the height of the inclined surface of the prism is high in the center direction of the pixel array and low in the radially outward direction.

The method of claim 1,

The refractive index of the prism is higher than the refractive index of the peripheral portion.

The method of claim 1,

A color filter array formed on the prism array; And

And a lens array formed on the color filter array.

Forming a pixel array on the substrate; And

And forming a prism array on the substrate, the prism array having a plurality of prisms having an inclined angle in a radially outward direction in a central region of the substrate, corresponding to each pixel.

The method of claim 6,

Forming a planarization layer on the prism array;

Forming a color filter array on the planarization layer; And

Forming a lens array on the color filter array.

The method of claim 6,

The inclined surface of the prism has a direction inclined radially outward from the center of the pixel array, the height of the inclined surface of the prism is high in the center direction of the pixel array and low in the radially outward direction.

The method of claim 6,

The refractive index of the prism is higher than the refractive index of the peripheral portion, the manufacturing method of the image sensor.

The method of claim 6,

The prism array is formed by a photo process using a gray scale mask.

A semiconductor substrate including a light receiving element in each pixel;

A metal wiring layer formed on the semiconductor substrate;

A prism array formed on the metal interconnection layer and having a prism disposed corresponding to each pixel; And

And a color filter array formed on the prism array.

The method of claim 11,

And a micro lens array formed on the color filter array.

The method of claim 11,

And a planarization film formed on the prism array.

The method of claim 11,

Forming a light receiving element in each pixel on the semiconductor substrate;

Forming a metal wiring layer on the semiconductor substrate;

Forming a prism array on which the prism is disposed corresponding to each pixel on the metallization layer; And

And forming a color filter array on the prism array.

The method of claim 17,

And forming a planarization film on the prism array.

The method of claim 17,

And the prism array is formed by a photo process using a gray scale mask.