KR100989987B1 - Manufacturing method of CMOS image sensor preventing the peeling phenomenon of overcoating layer - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a CMOS image sensor, and in particular, to prevent peeling by protecting the overcoating layer from moisture by performing a silicide treatment on an overcoating layer for planarization. to be. To this end, the present invention comprises the steps of forming a color filter on a substrate on which the relevant elements, including photodiode; Forming an overcoating layer on the color filter; And silicating the overcoating layer to form a silicon layer on a surface of the overcoating layer.

Overcoating Layer, Filling, Silicide, Organic Photoresist

Description

Fabrication method for cmos image sensor with protecting peeling of over coating layer             

1 is a cross-sectional view showing a cross section of a CMOS image sensor according to the prior art,

2A-2B illustrate a process of processing an overcoating layer in accordance with one embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

20: substrate

21: device isolation film

22: photodiode

23: interlayer insulating film

24: metal wiring

25: passivation film

26: color filter

27; Overcoat Layer                 

28 silicon layer

The present invention relates to a CMOS image sensor, and more particularly, to a method of manufacturing a CMOS image sensor that prevents the peeling phenomenon of the overcoating layer by performing a chemical treatment on the overcoating layer used for planarization purposes.

In general, an image sensor is a semiconductor device that converts an optical image into an electrical signal. Among them, a charge coupled device (CCD) includes individual metal-oxide-silicon (MOS) capacitors. A device in which charge carriers are stored and transported in a capacitor while being in close proximity to each other. Complementary MOS image sensors use CMOS technology that uses a control circuit and a signal processing circuit as peripheral circuits. A device employing a switching scheme that creates MOS transistors as many as pixels and sequentially detects outputs using the MOS transistors.

CCD (charge coupled device) has many disadvantages such as complicated driving method, high power consumption, high number of mask process steps, complicated process, and difficult to implement signal processing circuit in CCD chip. Recently, in order to overcome such drawbacks, the development of CMOS image sensors using sub-micron CMOS manufacturing techniques has been studied. The CMOS image sensor forms an image by forming a photodiode and a MOS transistor in a unit pixel and sequentially detects signals in a switching method, and implements an image by using a CMOS manufacturing technology, which consumes less power and uses 30 to 40 masks as many as 20 masks. Compared to CCD process that requires two masks, the process is very simple, and it is possible to make various signal processing circuits and one chip, which is attracting attention as the next generation image sensor.

As described above, the color filter array (CFA) is composed of three colors, red, green, and blue, or yellow, magenta, and cyan. It consists of three colors of).

In addition, the image sensor is composed of a light sensing portion for detecting light and a logic circuit portion for processing the detected light as an electrical signal to make data. The ratio of the area of the light sensing portion in the entire image sensor element to increase the light sensitivity ( Efforts have been made to increase the fill factor, but since the logic circuit part cannot be removed, this effort is limited in a limited area.

Therefore, a condensing technology has emerged to change the path of light incident to an area other than the light sensing portion to raise the light sensitivity, and to collect the light sensing portion. For this purpose, the image sensor uses a microlens on the Cali filter. The method of forming is used.

FIG. 1 is a cross-sectional view illustrating a CMOS image sensor including a color filter and a micro lens as described above. Referring to the structure of the conventional CMOS image sensor, first, an active region and a field region are formed on a semiconductor substrate 10. A device isolation film 11 to be defined is formed, and photosensitive means 12 made of photodiode or the like is formed in each unit pixel.

After the device isolation film 11, the light sensing means 12, and the transistors (not shown) are formed in this manner, an interlayer insulating film is formed on the semiconductor substrate 10 and the metal wiring 14 is formed thereafter. Although FIG. 1 illustrates the case where one metal wire 14 is used, more metal wires may be used.

After the final metal wiring 14 is formed, a passivation film 15 is formed on the final metal wiring to protect the device from moisture, scratches, and the like. A color filter 16 is formed on the passivation layer 15 to realize a color image. A color filter typically uses a dyed photoresist, and one color filter 16 is formed for each unit pixel. The color is separated from the light incident on the light sensing means 12.

Since the color filter 16 is usually formed with a step, it is necessary to eliminate the step caused by the color filter in order for the microlenses to be formed in the subsequent process to be formed on the flattened surface. For this purpose, the planarization film 17 is formed on the color filter 16. Then, the microlens 18 is formed on the planarization film 17. The microlens 18 may form a dome-shaped microlens by flowing a rectangular photosensitive film.

An over coating layer (OCL) is used as the planarization layer 17, and an organic photoresist is generally used as the over coating layer. Unlike the photoresist used in the general mask process, the organic photoresist used as the overcoating layer is not removed until the image sensor is finished and is also very hygroscopic.

In general, a curing process is performed through a thermal process to remove the solvent remaining inside the overcoating layer and to protect the overcoating layer from the surrounding moisture. There is a limit to protecting the layer.

Therefore, in the related art, due to the hygroscopicity of the overcoating layer, a peeling phenomenon occurs in which the overcoating layer is completely peeled off during the packaging process and the test process of the product.

An object of the present invention is to provide a method for manufacturing a CMOS image sensor that prevents peeling by forming a silicon layer through a chemical treatment on the surface of the overcoating layer.

According to an aspect of the present invention, there is provided a method of manufacturing a CMOS image sensor, the method including: forming a color filter on a substrate on which related elements including a photodiode are formed; Forming an overcoating layer on the color filter; And silicating the overcoating layer to form a silicon layer on a surface of the overcoating layer.

The present invention protects the overcoating layer from moisture by forming a silicon layer on the surface of the overcoating layer after a sillation process after forming the overcoating layer.

Hereinafter, the most preferred embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily implement the technical idea of the present invention.

2A to 2B are diagrams illustrating a method of manufacturing a CMOS image sensor according to an exemplary embodiment of the present invention, which will be described with reference to the drawing.

FIG. 2A is a view showing the formation of the overcoating layer after the color filter is formed. The process of forming the color filter 26 and forming the overcoating layer 27 on the color filter 26 is shown in FIG. Same as the prior art.

That is, the device isolation film 21 defining the active region and the field region is formed on the semiconductor substrate 20, and the light sensing means 22 made of photodiode or the like is formed in each unit pixel.

After the device isolation film 21, the light sensing means 22, and the transistors (not shown) are formed, the interlayer insulating film 23 is formed on the semiconductor substrate 20, and then the metal wiring 24 is formed on the interlayer insulating film. ) Is formed. Although FIG. 2A illustrates the case where one metal wire 24 is used, more metal wires may be used.

After the final metal wiring 24 is formed in this manner, the passivation film 25 is formed on the final metal wiring to protect the device from moisture, scratches, and the like. A color filter 26 is formed on the passivation layer 25 to realize a color image. A color filter typically uses a dyed photoresist, and one color filter 26 is formed for each unit pixel. The color is separated from the light incident on the light sensing means 22.

Since the color filter 26 is usually formed with a step, the step due to the color filter must be eliminated in order for the microlens to be formed in the subsequent process to be formed on the flattened surface. To this end, an overcoating layer 27 is formed on the color filter 26.

The overcoating layer is typically an organic photoresist, and after forming the overcoating layer 27, the wafer is placed in a Hexa Methyl Cyclo Tri Silazane (HMCTS) oven and heated for a predetermined time. The surface of the overcoating layer 27 is silized.

When the silicon layer 28 is formed on the surface of the overcoating layer 27 through such a silicide, it is possible to reliably protect the overcoating layer from the surrounding moisture, thereby preventing the peeling phenomenon which is a problem in the past. .

In an embodiment of the present invention, the HMCTS oven is used for the silicide, but in addition, HMDS (Hexa Methyl Di Silazane) may be used as the silicide material formed on the overcoating layer.

In this way, the surface of the overcoating layer is silized using HMCTS and HMDS, thereby preventing the penetration of the overcoating layer.

After the surface of the overcoating layer 27 is silized to form the silicon layer 28, the microlens 29 is formed on the silicon layer 28.

As described above, the present invention is not limited to the above-described embodiments and the accompanying drawings, and the present invention may be variously substituted, modified, and changed without departing from the spirit of the present invention. It will be apparent to those of ordinary skill in the art.

When the present invention is applied to the CMOS image sensor, the peeling phenomenon of the overcoating layer can be prevented, thereby improving the reliability of the device.

Claims (3)

In the method of manufacturing the CMOS image sensor, Forming a color filter on the substrate on which the related elements including the photodiode are formed; Forming an overcoating layer on the color filter; And Silicifying the overcoating layer to form a silicon layer on a surface of the overcoating layer Method for manufacturing a CMOS image sensor comprising a. The method of claim 1, The material used for the silicide treatment is HMCTS (Hexa Methyl Cyclo Tri Silazane) manufacturing method of the CMOS image sensor, characterized in that. The method of claim 1, The material used for the silicide treatment is a method of manufacturing a CMOS image sensor, characterized in that HMDS (Hexa Methyl Di Silazane).

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