KR20100078083A - Image sensor, and method for fabricating thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image sensor and a method of manufacturing the same, in particular, forming an interlayer insulating film including a plurality of metal wirings on a semiconductor substrate including a photodiode, Forming a trench in the trench, forming a protective insulating film on the entire surface of the semiconductor substrate including the trench, and sequentially performing a sintering and heat treatment process on the semiconductor substrate on which the protective insulating film is formed. And a step of sequentially forming a color filter array, a planarization film, and a microlens on the protective insulating film in the trench.

Description

Image sensor, and method for manufacturing the same

TECHNICAL FIELD The present invention relates to semiconductor technology, and more particularly, to an image sensor and a manufacturing method thereof.

In general, an image sensor is a semiconductor device that converts an optical image into an electrical signal. A charge coupled device (CCD) is a device in which individual metal-oxide-silicon (MOS) capacitors are very close to each other. A device in which a charge carrier is stored and transported in a capacitor while in position.

Complementary MOS (CMOS) image sensor uses CMOS technology that uses a control circuit and a signal processing circuit as peripheral circuits to make MOS transistors by the number of pixels and uses them. It is a device that employs a switching system that sequentially detects output.

Meanwhile, in the related art, the following structure is applied to improve the sensitivity of the CMOS image sensor.

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

Referring to FIG. 1, a photodiode 11 is provided in the semiconductor substrate 10. Here, the semiconductor substrate 10 is defined as a photo region in which the photodiode 11 is formed and a peripheral region in which peripheral circuits including metal wirings 13, transistors, etc. are formed around the photo region.

An interlayer insulating film 12 including a plurality of metal wires 13 is provided on the semiconductor substrate 10 including the photodiode 11 as described above. Here, a contact plug 14 may be further provided in the interlayer insulating layer 12 to electrically connect the plurality of metal wires 13.

Next, a trench is formed by removing a portion of the upper side of the interlayer insulating layer 12 formed on the photodiode 11 by etching in the photo region, and the color filter array 16 sequentially formed in the trench is planarized. A film 17 and a microlens 18 are provided.

By forming a trench on the upper side of the interlayer insulating film 12 as described above, the color filter array 16, the flattening film 17 and the microlens 18 are provided in the trench, thereby improving the sensitivity of the image sensor.

However, there is a problem that dark defects occur due to excessive plasma damage generated by the etching process for forming the trench. The low light characteristic on the chip edge side due to the dark defect has a problem of degrading the image sensor.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image sensor and a method for manufacturing the same, which are designed to prevent excessive plasma damage caused by an etching process in a structure for improving the sensitivity of the image sensor.

A feature of the image sensor manufacturing method according to the present invention for achieving the above object is the step of forming an interlayer insulating film including a plurality of metal wiring on a semiconductor substrate including a photodiode, the interlayer insulating film on the photodiode Forming a trench in the trench, forming a protective insulating film on the entire surface of the semiconductor substrate including the trench, and sequentially performing a sintering and heat treatment process on the semiconductor substrate on which the protective insulating film is formed. And sequentially forming a color filter array, a planarization film, and a microlens on the protective insulating film in the trench.

The trench may be formed by etching a portion of the interlayer insulating layer on the photodiode by dry etching using plasma. Here, a silicon nitride layer (SiN) may be deposited as the protective insulating layer in order to cure plasma damage caused by dry etching using the plasma.

Features of the image sensor according to the present invention for achieving the above object, a semiconductor substrate including a photodiode, an interlayer insulating film including a plurality of metal wiring on the semiconductor substrate, and corresponding to the position of the photodiode A trench provided on the interlayer insulating film, a silicon nitride film deposited on the entire surface of the semiconductor substrate including the trench, and a color filter array, a planarization film, and a microlens sequentially provided on the silicon nitride film in the trench. Will be.

In the present invention, the color filter array, the planarization film, and the microlens are provided in the trench formed on the upper side of the interlayer insulating film to improve the sensitivity of the image sensor and to prevent excessive plasma damage generated during the trench formation process. This suppresses the occurrence of dark defects and improves deterioration of the image sensor.

In particular, in the present invention, excessive plasma damage can be prevented by further using a silicon nitride film as a protective insulating film in the trench in which the color filter array, the planarization film, and the microlens are formed.

Other objects, features and advantages of the present invention will become apparent from the detailed description of the embodiments with reference to the accompanying drawings.

Hereinafter, with reference to the accompanying drawings illustrating the configuration and operation of the embodiment of the present invention, the configuration and operation of the present invention shown in the drawings and described by it will be described by at least one embodiment, By the technical spirit of the present invention described above and its core configuration and operation is not limited.

Hereinafter, an image sensor and a manufacturing method thereof according to the present invention will be described in detail with reference to the accompanying drawings.

The image sensor described in the present invention is preferably a CMOS image sensor.

2A to 2B are cross-sectional views illustrating a CMOS image sensor structure and process according to the present invention.

First, the structure of the CMOS image sensor shown in FIGS. 2A to 2B will be described.

In the CMOS image sensor according to the present invention, a photodiode 110 is provided in the semiconductor substrate 100. Here, the semiconductor substrate 100 is defined as a photo region in which the photodiode 110 is formed, and a peripheral region in which peripheral circuits including the metal wire 130 and transistors are formed around the photo region.

An interlayer insulating layer 120 including a plurality of metal wires 130 is provided on the semiconductor substrate 100 including the photodiode 110 as described above. Here, a contact plug 140 for electrical connection of the plurality of metal wires 130 is further provided in the interlayer insulating layer 120.

In particular, a trench 200 is formed by etching a portion of the upper side of the interlayer insulating layer 120 in the photo region in which the photodiode 110 is formed. The trench 200 may be formed by etching the interlayer insulating layer 120 to a predetermined depth between the uppermost metal wirings M3 formed in the peripheral region. For example, the trench 200 may be formed to a depth of 1.1 μm.

In addition, in the CMOS image sensor of the present invention, a silicon nitride film (SiN) 150 is provided as a protective insulating film on the entire surface of the semiconductor substrate 100 including the trench 200. The silicon nitride film 150 is to improve excessive plasma damage generated in the process of forming the trench 200. The silicon nitride film 150 is sintered and heat treated to remove silicon crystal defects. For example, the silicon nitride film 150 may be formed to a thickness of 3000 kPa.

In addition, the CMOS image sensor of the present invention includes a color filter array 160, a planarization film 170, and a microlens 180 sequentially on the silicon nitride film 150 in the trench 200.

Hereinafter, a manufacturing process of the CMOS image sensor according to the present invention having the above-described structure will be described.

Referring to FIG. 2A, a photodiode 110 is formed on the semiconductor substrate 100.

Subsequently, an interlayer insulating film 120 including a plurality of metal wires 130 is formed on the semiconductor substrate 100 including the photodiode 110, and electrical connections of the plurality of metal wires 130 are formed in the interlayer insulating film 120. A contact plug 140 is also formed for this purpose.

Subsequently, the trench 200 is formed by partially etching the upper side of the interlayer insulating layer 120 on the photodiode 110 in the photo region through dry etching using plasma. The trench 200 may be formed by etching the interlayer insulating layer 120 to a predetermined depth between the uppermost metal wirings M3 formed in the peripheral region, and may be formed to have a depth of 1.1 μm.

Subsequently, as illustrated in FIG. 2B, a silicon nitride film (SiN) 150 is deposited to a thickness of 3000 으로써 as a protective insulating film on the entire surface of the semiconductor substrate 100 including the trench 200. The silicon nitride film is intended to improve damage due to plasma dry etching that is performed to form the trench 200.

Subsequently, the silicon nitride film 150 is sintered and heat treated. Sintering is carried out at about 450 degrees for about 30 minutes, using 20% H ₂ and 80% N. On the other hand, the heat treatment proceeds at 20 atm for about 30 minutes at about 420 degrees.

In the above heat treatment is deuterium anneal (deuterium anneal), deuterium is one isotope of hydrogen and chemical properties similar to hydrogen, but the mass number is 2. Therefore, since deuterium is used twice as much as the mass of deuterium heat treatment H ₂ , the bonding force is increased during heat treatment.

Subsequently, the color filter array 160, the planarization film 170, and the microlens 180 are sequentially formed on the sintered and heat treated silicon nitride film 150, particularly in the trench 200.

While the preferred embodiments of the present invention have been described so far, those skilled in the art may implement the present invention in a modified form without departing from the essential characteristics of the present invention.

Therefore, the embodiments of the present invention described herein should be considered in a descriptive sense, not in a limiting sense, and the scope of the present invention is shown in the appended claims rather than the foregoing description, and all differences within the scope are equivalent to the present invention. Should be interpreted as being included in.

1 is a cross-sectional view showing a CMOS image sensor structure according to the prior art.

2A to 2B are cross-sectional views for explaining the structure and process of a CMOS image sensor according to the present invention;

Claims (4)

Forming an interlayer insulating film including a plurality of metal interconnections on a semiconductor substrate including a photodiode; Forming a trench in the interlayer insulating film on the photodiode; Forming a protective insulating film on an entire surface of the semiconductor substrate including the trench; Sequentially performing sintering and heat treatment processes on the semiconductor substrate on which the protective insulating film is formed; And sequentially forming a color filter array, a planarization film, and a microlens on the protective insulating film in the trench. The method of claim 1, wherein the forming of the trench comprises: And forming the trench by etching a portion of the interlayer insulating layer on the photodiode by dry etching using plasma. The method of claim 2, wherein a silicon nitride layer (SiN) is deposited as the protective insulating layer to heal plasma damage caused by dry etching using the plasma. A semiconductor substrate including a photodiode; An interlayer insulating film including a plurality of metal wirings on the semiconductor substrate; A trench provided on the interlayer insulating layer corresponding to the position of the photodiode; A silicon nitride film deposited on the entire surface of the semiconductor substrate including the trench; And a color filter array, a planarization film, and a microlens that are sequentially provided on the silicon nitride film in the trench.

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