KR100718778B1 - Method for manufacturing image sensor - Google Patents

Abstract

The present invention is to provide a method for manufacturing an image sensor that can suppress the reflection of light by preventing the formation of a gap between the color filters of different colors, the present invention provides a step of providing a substrate with a flattening film and And forming a plurality of first and second color filters spaced apart from each other on the planarization layer, and filling the empty space between the first and second color filters on the planarization layer. Applying a coating film, exposing the coating film without a mask until the upper surfaces of the first and second color filters are exposed, and developing the coating film to self-align between the first and second color filters. It provides an image sensor manufacturing method comprising the step of forming the third color filter.

Image sensor, color filter, blanket, exposure process, planarization.

Description

Image sensor manufacturing method {METHOD FOR MANUFACTURING IMAGE SENSOR}

1A and 1B are cross-sectional views illustrating a method of forming a color filter of an image sensor according to the prior art.

2A to 2D are cross-sectional views illustrating a method of forming a color filter of an image sensor according to an exemplary embodiment of the present invention.

-Explanation of symbols for the main parts of the drawings-

10, 20: planarization film

11, 21: blue color filter

12, 22: photoresist

12a, 22a: Green color filter

23: exposure process

25: planarization process

The present invention relates to an image sensor manufacturing method, and more particularly, to an image sensor manufacturing method having a color filter.

Recently, the demand of digital cameras is exploding with the development of video communication using the Internet. Moreover, the demand for small camera modules increases as the popularity of mobile communication terminals such as PDAs equipped with cameras, International Mobile Telecommunications-2000 (IMT-2000), Code Division Multiple Access (CDMA) terminals, etc. increases. Doing.

As a camera module, an image sensor module using a charge coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS) image sensor that is a basic component is widely used. The image sensor is arranged on the upper part of the light sensing unit for generating and accumulating photocharges from the outside to implement a color image. The color filter is composed of three colors of red, green, and blue, or three colors of yellow, magenta, and cyan.

1A and 1B are cross-sectional views illustrating a method of forming a color filter of an image sensor according to the prior art.

First, as shown in FIG. 1A, an OCL (Over) is used as the planarization film 10 to remove a step caused by the formation of a lower structure on a protective film (not shown) covering a predetermined lower structure constituting the image sensor. Coating layer).

Subsequently, color filters of different colors are formed on the planarization film 10. For example, first, a red color photoresist (not shown) for forming a red color filter (not shown) is applied, followed by an exposure and development process using a photo mask (not shown) to perform a red color filter (not shown). To form. Then, the blue color filter 11 is formed in the same manner.

In this case, since the process sequence of the red color filter and the blue color filter 11 may be reversed, only the blue color filter 11 is shown here for convenience of description.

Subsequently, a green color photoresist 12 for forming a green color is coated on the planarization film 10 on which the blue color filter 11 is formed.

Subsequently, as illustrated in FIG. 1B, an exposure and development process using a predetermined photo mask (not shown) for forming a green color is performed to form the green color filter 12a.

However, when the plurality of color filters are formed according to the related art, the green color filter 12a and the blue color are misaligned due to mis-alignment of the photo mask used in the exposure process for forming the green color filter 12a. A gap (see 'A' region) is formed between the filters 11. This gap is filled by another planarization film that is subsequently deposited to remove the step formed by the color filter, or just left empty.

As such, when a gap is generated between color filters of different colors, diffuse reflection of light occurs when light having a relatively large incident angle is incident from the outside. Such diffuse reflection occurs due to films having different refractive indices (or light transmitting characteristics). For reference, when the gap is not filled with the planarization film and is left as an empty space, the area where the gap is generated has the refractive index of air (about 1.0).

The present invention proposed to solve the problems of the prior art as described above, the object of the present invention is to provide a method for manufacturing an image sensor that can suppress the diffuse reflection of light by preventing the formation of gaps between color filters of different colors. have.

According to an aspect of the present invention, a flattening film is formed on a substrate, and a red color filter and a blue color filter are formed on the flattening film, wherein the red color filter and the blue color filter Forming a spaced distance between them wider than a width; and green color filter on the substrate including the red color filter and the blue color filter to fill the empty space between the red color filter and the blue color filter. Coating the coating film, exposing the coating film, exposing the coating film such that the exposure target has a predetermined depth from an upper portion of the red color filter and the blue color filter, and developing the coating film. Forming the green color filter self-aligned between the red color filter and the blue color filter, wherein the exposure Forming the green color filter to have a lower thickness than the red color filter and the blue color filter by a target depth, and planarizing the red color filter, the blue color filter, and the green color filter. It provides a sensor manufacturing method.

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DETAILED DESCRIPTION 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 technical idea of the present invention. In addition, in the drawings, the thicknesses of layers and regions are exaggerated for clarity, and in the case where the layers are said to be "on" another layer or substrate, they may be formed directly on another layer or substrate or Or a third layer may be interposed therebetween. Also, throughout the specification, the same reference numerals denote the same components.

Example

2A to 2D are cross-sectional views illustrating a method of forming a color filter of an image sensor according to an exemplary embodiment of the present invention. Here, an example of a method of manufacturing an image sensor including three color filters of red, green, and blue, which are three primary colors of light, will be described.

First, as shown in FIG. 2A, a lower structure (not shown) formed by a lower structure on a substrate (not shown) including various components for forming an image sensor such as a photodiode, a transistor, and a metal wiring is formed due to the lower structure. The planarization film 20 is deposited to remove the step. For example, an OCL film is deposited.

In this case, a protective film (not shown) for protecting the surface of the lower structure may be formed at the bottom of the planarization layer 20 along the step of the upper portion of the lower structure. Such a protective film may be formed of a structure in which an oxide film and a nitride film are stacked or one single film structure of both.

Subsequently, a plurality of red color filters (not shown) and blue color filters 21 spaced apart from each other are formed on the planarization film 20 by applying a known color filter formation technique. For example, after the photoresist (not shown) is applied to the planarization film 20 with a coating film for red color filter, a photoresist (not shown) is performed to perform exposure and development processes on the planarization film 20. A red color filter is formed. Then, a photoresist (not shown) is coated with a coating film for a blue color filter, and then a photomask (not shown) is subjected to an exposure and development process using a photo mask (not shown) so as not to overlap the red color filter. Blue color filter 21 is formed.

In this case, the order of forming the red color filter and the blue color filter 21 may be the first to form the blue color filter 21. Here, only the blue color filter 21 is shown for convenience of description.

Subsequently, the photoresist 22 is coated on the entire structure including the blue color filter 21 with a coating film for green color filters.

Subsequently, as illustrated in FIG. 2B, an exposure process is performed without using a photo mask by using the upper surfaces of the blue color filter 21 and the red color filter (not shown) as target lines (T). That is, the target line T is set lower than the upper surfaces of the blue color filter 21 and the red color filter to irradiate light to the photoresist 22.

Next, as shown in FIG. 2C, a developing process is performed to remove the photoresist 22 from the portion to which the light is irradiated, that is, from the upper surface of the photoresist 22 to the target line T (see FIG. 2B). . As a result, the green color filter 22a is self-aligned in the empty space between the blue color filter 21 and the red color filter (not shown).

That is, in the embodiment of the present invention by performing a blanket exposure process performed without a mask to form the green color filter 22a, a gap between color filters of different colors is prevented due to misalignment of the mask. can do. Therefore, it is possible to prevent the diffuse reflection of the image sensor to improve the optical characteristics.

Subsequently, as shown in FIG. 2D, the planarization process 25 is performed to remove the step difference caused by the color filters of the different colors. For example, the blue color filter 21, the red color filter (not shown), and the green color filter 22a are planarized by performing an etching-back or chemical mechanical polishing (CMP) process.

As described above, according to the exemplary embodiment of the present invention, the step of removing the step between the color filters of the different colors by performing the planarization process such as the front etching process, thereby eliminating the OCL film that is formed separately to remove the step formed by the color filter. can do. Therefore, the manufacturing process of the overall image sensor can be simplified.

In addition, by reducing the height step of the overall image sensor it is possible to reduce the distance between the microlens formed on the color filter to correspond to the color filter and the photodiode formed in the substrate corresponding thereto. Therefore, it is possible to improve the sensitivity of the image sensor.

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

For example, in the above-described embodiment of the present invention, an image sensor having a color filter consisting of three colors of red, green, and blue, which are three primary colors of light, is used as an example. In addition, yellow (Y) and magenta (Magenta) are complementary colors. Mg) and cyan; Cy can also be applied to an image sensor having a color filter consisting of three colors.

As described above, according to the present invention, a blanket exposure process performed without a mask is performed to form a final color filter, thereby preventing a gap between color filters of different colors due to misalignment of the mask. can do. Therefore, it is possible to prevent the diffuse reflection of the image sensor to improve the optical characteristics.

Further, according to the present invention, after the final color filter is formed, a flattening process is performed to remove the step between the color filters of different colors, and thus another flattening film that is formed separately to remove the step formed by the color filter ( For example, the formation of the OCL film) can be omitted. Therefore, the manufacturing process of the overall image sensor can be simplified.

In addition, the height difference of the overall image sensor may be reduced to reduce the distance between the microlens formed on the color filter so as to correspond to the color filter and the photodiode corresponding to the color filter. Therefore, it is possible to improve the sensitivity of the image sensor.

Claims (9)

Forming a planarization film on the substrate; Forming a red color filter and a blue color filter on the planarization layer, wherein the separation distance between the red color filter and the blue color filter is wider than the width of the red color filter and the blue color filter; Coating a coating film for a green color filter on the substrate including the red color filter and the blue color filter such that an empty space between the red color filter and the blue color filter is filled; Exposing the coating film, exposing the coating film such that the exposure target has a predetermined depth from an upper portion of the red color filter and the blue color filter; The coating layer is developed to form the green color filter which is self-aligned between the red color filter and the blue color filter, wherein the green color filter has a lower thickness than the red color filter and the blue color filter due to the exposure target depth. Forming to have; And Planarizing the red color filter, the blue color filter and the green color filter Image sensor manufacturing method comprising a. delete The method of claim 1, Wherein the planarization step is an image sensor manufacturing method performed by a front surface etching process or a chemical mechanical polishing process. delete The method of claim 1, Forming the red color filter, Applying a coating film for a red color filter on the planarization film; And Patterning the coating layer by performing an exposure and development process using a mask; Image sensor manufacturing method comprising a. delete The method of claim 1, Forming the blue color filter, Coating a blue color filter coating film on the planarization film; And Patterning the coating layer by performing an exposure and development process using a mask; Image sensor manufacturing method comprising a. delete The method of claim 1, The coating film is an image sensor manufacturing method consisting of a photoresist.

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