KR20090068655A - Making method of image sensor - Google Patents

Abstract

A manufacturing method of an image sensor is provided to prevent cross-talk between adjacent pixels by enhancing efficiency of received light and preventing an influence of the light on the adjacent pixels. A field oxide layer is formed on a semiconductor substrate(11) in order to define an active region and a field region. A photodiode(12) is formed on the active region. An etch barrier layer is formed on a semiconductor. A first insulating layer is formed on the etch barrier. A photolithography process is performed to expose the first insulating layer as much as the area of the photodiode. A dry etch process is performed to form a well. The well is filled with an organic material having a high refractive index.

Description

Manufacturing method of image sensor {MAKING METHOD OF IMAGE SENSOR}

The present invention relates to a method of manufacturing an image sensor, and more particularly, to a method of manufacturing a CMOS image sensor to prevent light passing through a color filter from being reflected inside a well and transmitted to a photodiode. It is about.

In general, an image sensor is a semiconductor device that converts an optical image into an electrical signal, and may be roughly divided into a CMOS image sensor and a charge coupled device.

In manufacturing such an image sensor, efforts are being made to increase the photo sensitivity of the image sensor.

For example, the CMOS image sensor is composed of a pixel array unit including a photodiode for detecting light and a CMOS logic circuit unit for processing the detected light into an electrical signal and converting the data into a photodiode. Efforts have been made to increase the ratio of the area of light or to reduce the path of light input and to form a microlens on the top to collect more light into the photodiode region.

1 is a view showing the structure of an image sensor according to the prior art.

Referring to FIG. 1, a field oxide film 12 is formed on a P-type semiconductor substrate 11, a P-type well 13 is formed in a P-type semiconductor substrate, and a predetermined surface of the P-type semiconductor substrate 11 is formed. A gate of the reset transistor is formed, and an N-type diffusion layer 14 and a P diffusion layer 15 are formed in the photodiode region of the P-type well 13 on one side of the gate. The N source / drain 16 is formed in the P-type well 11 on the other side of the gate. Then, a multi-layer interlayer insulating film 17 is formed on the entire surface of the P-type semiconductor substrate 11, and metal wirings M3 and 18 in which the upper portion of the photodiode is opened between the multi-layer interlayer insulating film 17 are formed. It is. Here, the metal wirings M1 and M2 will be omitted.

However, such a prior art requires that light incident on the photodiode pass through the multilayer interlayer insulating film 17, so that the amount of received light scatters to other than the photodiode.

Thus, there is a problem that the received light is not used efficiently.

The present invention is to solve the above problems, an object of the present invention to provide a method of manufacturing an image sensor that can minimize the loss of light generated by the scattered light to a region other than the photodiode. .

According to an aspect of the present invention, there is provided a method of manufacturing an image sensor, the method including: forming an etch barrier layer on a semiconductor; forming a first insulating layer on the etch barrier layer; Performing a photolithography process to expose the area of the diode, dry etching to form a well, filling an organic material having a high refractive index inside the well, and forming a color on top of the layer on which the organic material is formed. Forming a filter layer.

Herein, the organic material is a novolac or a planarization layer photoresist, and when the well is formed into a novolac, an etch-back of extra novolac is performed through a dry etching process. ) To form a planarization layer.

On the other hand, when the well (well) is formed by a planarization layer photoresist, it is characterized in that the planarization through an exposure process.

At this time, the novolac or the planarization layer photoresist is characterized in that the refractive index is higher than the insulating material of the metal wiring layer.

The organic material is further formed to a thickness of 50 to 100 nm after filling the inside of the well.

In addition, the organic material is characterized in that it is formed of a wave guide (wave guide) of light received in a planar type (planar type).

According to the present invention described above, by using all the received light, the efficiency is increased, and since it does not affect other adjacent pixels, there is an effect of preventing cross talk between adjacent pixels.

In addition, since the efficiency of the received light is increased, the sensitivity can be improved, and since the size of the microlens can be reduced based on the same amount of received light, the degree of integration can be improved.

Hereinafter, the accompanying drawings for the manufacturing method of the image sensor according to an embodiment of the present invention will be described in detail.

2A through 2D are cross-sectional views sequentially illustrating a manufacturing process of an image sensor according to an exemplary embodiment of the present invention.

First, a field oxide film (not shown) defining an active region and a field region is formed on the semiconductor substrate 11. P-type substrate is mainly used here as a semiconductor substrate. Next, the photodiode 12 is formed in a predetermined region on the active region.

Although not shown in detail in FIG. 2A, the photodiode 12 is typically composed of an N-type ion implantation region and a P-type ion implantation region, and it is common to form a P / N / P photodiode with a P-type substrate. . However, for convenience of description, in FIG. 2A of the present invention, only 'photo diode' is simply indicated.

Next, although not shown in FIG. 2A, the gate patterning process of the transistor proceeds. After the device isolation film, the related device including the photodiode 12 and the transistor are formed, various insulating films such as pre metal dielectric (PMD) and interlayer insulating film (IMD) are formed on the semiconductor substrate 11. And a plurality of metal wirings are formed. However, in FIG. 2A, all of them are represented by one insulating layer 14 for convenience of description.

In addition, the first metal wiring 13 and the final metal wiring 15 are shown in FIG. 2A, and a passivation film 16 is formed on the top of the final metal wiring 15 to protect the device from moisture or scratches. do.

Next, as shown in FIG. 2B, a lithography process is performed to expose the area of the photodiode, and a dry etching process is performed on the insulating layer to the depth of the first metal wire 13. ).

Then, as shown in FIG. 2C, the well 17 is filled with photo resist 18 of Novolac or planarization layer.

At this time, the refractive index of the novolak or flattening layer photoresist filled in the well has a larger value than the refractive index n to 1.4 at the visible light wavelength.

Further, since the absorption refractive index is k to 0 at the visible light wavelength, there is almost no absorption.

As such, the novolac or flattening layer photoresist is a product that is widely commercially available and is easy to purchase. Both materials have a planar-type property, so the bottom of the well is filled up to fill the well. Can be filled well without voids.

At this time, fill all the inside of the well and then further apply a thickness of about 50 ~ 100nm more than the height of the well is formed.

Thereafter, when the inside of the well is filled with novolak, the extra novolak is etched back through dry etching as in the copper dual damascene process.

On the other hand, when the inside of the well is filled using the planarization photoresist, exposure is performed with exposure energy of a suitable intensity.

After the planarization process is performed to planarize the well layer, a color filter 17 is formed. The color filter is formed by applying a color filter forming material and patterning the same using a suitable mask. As a color filter forming material, a dyed photoresist is mainly used.

As the color filter 17 described above, a dyed photoresist is typically used, and one color filter 17 is formed for each unit pixel to separate colors from incident light.

The color filter 17 is typically composed of three colors of red, green, and blue, and adjacent color filters are formed to overlap each other slightly.

Since the adjacent color filters are formed to overlap each other slightly as described above, a step resulting from this is formed to form an over coating layer (OCL) 18 on the color filter 17 to compensate for this.

Although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the above-described embodiments, and the present invention is not limited to the above-described embodiments without departing from the spirit of the present invention as claimed in the claims. Of course, any person skilled in the art can make various modifications, and such changes are within the scope of the claims.

1 is a view showing the structure of an image sensor according to the prior art,

2A through 2D are cross-sectional views sequentially illustrating a manufacturing process of an image sensor according to an exemplary embodiment of the present invention.

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

11 semiconductor substrate 12 photodiode

13 first metal wiring 14 interlayer insulating film

15: final metal wiring 16: passivation film

17 color filter 18 flattening film

Claims (7)

Forming an etch barrier layer on the semiconductor; Forming a first insulating layer on the etch barrier layer; Performing a photolithography process to expose the first insulating layer by the photodiode area, and dry etching to form a well; Filling the well with an organic material having a high refractive index; And Forming a color filter layer on top of the layer on which the organic material is formed. The method of claim 1, And said organic material is a novolac or planarization layer photoresist. The method of claim 2, When the inside of the well is formed as a novolak, an image sensor, which is formed by etching the excess novolak through a dry etching process, and forming a planarization layer. Method of preparation. The method of claim 2, When the well (well) is formed in the planarization layer photoresist, the manufacturing method of the image sensor, characterized in that the planarization through an exposure process. The method of claim 2, And the novolac or planarization layer photoresist has a higher refractive index than the insulating material of the metallization layer. The method of claim 1, The organic material is a method of manufacturing an image sensor, characterized in that further filling the inside of the well (well), the thickness of 50 ~ 100nm range. The method of claim 1, The organic material is a manufacturing method of an image sensor, characterized in that formed by a wave guide (wave guide) of light received in a planar type (planar type).

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