KR100868653B1 - Image sensor and method for manufacuring thereof - Google Patents

Abstract

The generation of the noise and cross-talk can be prevented by blocking the light which is incident to the gap region of the micro lens. The image sensor comprises as follows. The semiconductor substrate(10) includes optical detecting device(20). The interlayer insulating film(30) having a lower wiring is formed in the semiconductor substrate. The micro lens(50) is formed at the location corresponding to the optical detecting device in the interlayer insulating film. The shielding layer(36) is positioned in the gap region between the micro lens, and is formed in the interlayer insulating film. The shielding layer is formed in the gap region between the micro lens. The shielding layer is formed with one or their laminate among Ti, TiN, and W. The interlayer insulating film and oxide film are the same material.

Description

Image sensor and manufacturing method thereof

1 to 6 are cross-sectional views illustrating a method of manufacturing the image sensor according to the embodiment.

This embodiment relates to an image sensor and a manufacturing method thereof.

An image sensor is a semiconductor device that converts an optical image into an electrical signal. The image sensor is largely a charge coupled device (CCD) and a complementary metal oxide silicon (CMOS) image sensor. (CIS).

In the CMOS image sensor, a photo diode and a MOS transistor are formed in a unit pixel to sequentially detect an electrical signal of each unit pixel in a switching manner to implement an image.

In particular, apart from the conventional method of arranging one color of red-green-blue in one pixel (pixel), all three colors are arranged vertically in one pixel to have a horizontal structure. A vertical image sensor has been developed that can achieve about three times higher image quality than an image sensor.

The vertical image sensor can express various colors without a separate color filter process, thereby increasing productivity and reducing production costs.

The vertical image sensor includes a unit pixel including a photo diode on a semiconductor substrate and a logic circuit area for processing and converting a signal from the unit pixel into data.

Efforts have been made to increase the fill factor of the light sensing region in the entire image sensor device in order to increase the light sensitivity. However, since the logic circuit region cannot be removed, this effort is limited in a limited area.

Therefore, a condensing technology that changes the path of light incident to a region other than the light sensing region and collects the light sensing region in order to increase the light sensitivity has emerged. A method of forming a microlens is used for the condensing.

However, even if the microlens is formed, not all of the refracted light is collected in the light sensing region.

In particular, when the light refracted by the microlens enters into the CMOS circuit region other than the light sensing region, the light constitutes a noise component and causes a deterioration in image quality, thereby acting as an adverse effect on the characteristics of the image sensor.

To this end, after forming a metal wiring layer and a protective layer on which the metal wiring connected to the unit pixel is formed, a light blocking layer is partially formed on the protective layer, but the manufacturing process is increased and the product yield is increased due to the complicated and additional process. Will result in a decrease.

Embodiments relate to an image sensor and a method of manufacturing the same, which can improve the quality of an image sensor by blocking light incident on a CMOS circuit of a unit pixel when forming a microlens.

An image sensor of an embodiment includes a semiconductor substrate including a photosensitive device; An interlayer insulating film having lower wirings formed on the semiconductor substrate; A micro lens formed in a position corresponding to the light sensing element in the interlayer insulating film; And a blocking film disposed in the gap region between the microlenses and formed in the interlayer insulating film.

In addition, the image sensor manufacturing method of the embodiment comprises the steps of forming an interlayer insulating film including a lower wiring on a semiconductor substrate including a light sensing element; Forming a photoresist pattern on the interlayer insulating film; Etching the interlayer insulating film and forming a blocking film; Forming an oxide film on the interlayer insulating film on which the blocking film is formed; And etching the oxide film to form a microlens.

Hereinafter, a manufacturing process of the image sensor according to the present embodiment will be described with reference to the drawings.

In the description of this embodiment, when described as being formed "on / over" of each layer, the on / over is directly or through another layer. It includes everything formed indirectly.

In the drawings, the thickness or size of each layer is exaggerated, omitted, or schematically illustrated for convenience and clarity of description. In addition, the size of each component does not necessarily reflect the actual size.

6 illustrates an image sensor according to an embodiment.

The image sensor of the embodiment includes a semiconductor substrate 10 including a light sensing element 20; An interlayer insulating film 30 having a lower wiring formed on the semiconductor substrate 10; A microlens 50 formed at a position corresponding to the photosensitive device 20 on an upper end of the interlayer insulating film 30; A device disposed in the gap region between the microlenses 50 and formed on the interlayer insulating layer 30 other than the blocking layer 36 formed by being inserted into the interlayer insulating layer 30 and the region in which the microlens 50 is formed. The protective film 41 is included.

The photosensitive device 20 is formed to include a red photodiode, a green photodiode, and a blue photodiode.

The interlayer insulating film 30 may be formed of an oxide film.

In addition, the microlens 50 may be formed of the same material as the interlayer insulating layer 30, and a part of the microlens 50 may be formed of the interlayer insulating layer 30.

The blocking layer 36 blocks light that does not pass through the microlens 50 to prevent light from entering the CMOS circuit area, thereby preventing crosstalk and noise.

The blocking layer 36 may be formed of any one of Ti, TiN, W, or a stack thereof. The blocking layer 36 may be formed by contacting a plurality of adjacent microlenses 50.

The device protection film 41 may protect the device from moisture or external physical impact, and may be formed of an oxide film.

Hereinafter, a manufacturing method of an image sensor according to an exemplary embodiment will be described with reference to FIGS. 1 to 6.

Referring to FIG. 1, a pixel region including a photosensitive device 20 and a peripheral circuit region (not shown) are formed in a semiconductor substrate 10.

The pixel region includes a photosensitive device 20 and a CMOS transistor structure (not shown) for processing light generated by the photosensitive device 20.

The photosensitive device 20 is formed by including a red photodiode, a green photodiode, and a blue photodiode, and thus, three colors in one pixel. All are arranged vertically to achieve high quality images.

In addition, the photosensitive device 20 may express various colors without a separate color filter process.

An interlayer insulating layer 30 having metal wirings (not shown) is formed on the semiconductor substrate 10 including the pixel region.

The metal line may be connected to the power line, the signal line, and the pixel area, and may be disposed under the blocking layer to be formed later so as not to block the light incident to the photosensitive device 20.

The interlayer insulating film 30 may be formed of an oxide film, and may be formed of a material such as a microlens formed thereafter.

The first oxide film 40 is deposited on the interlayer insulating film 30 on which the metal wiring is formed.

Subsequently, the first photoresist pattern 50 is formed on the first oxide film 40 and the first oxide film is etched to form the device protection film 41 as shown in FIG. 2.

The device protective film 41 is formed to protect the device from moisture or external physical impact.

The ashing process is performed to remove the first photoresist pattern 50.

Subsequently, a second photoresist pattern 52 is formed on the interlayer insulating layer 30 on which the device protection layer 41 is formed, and the interlayer insulating layer 30 is etched. As shown in FIG. 3, an interlayer insulating layer ( 30) the groove 34 is formed in the upper portion.

Then, the blocking film 36 is deposited in the groove 34.

Since the blocking layer 36 is formed in the gap region between the microlenses formed thereafter, the blocking layer 36 may block light that does not pass through the microlens.

The blocking layer 36 may be formed of any one of Ti, TiN, W, or a stack thereof by a process of sputtering or chemical vapor deposition (CVD).

As shown in FIG. 4, an ashing process is performed to remove the second photoresist pattern 52.

Subsequently, an HDP CVD (High Density Plasma Chemical Vapor Deposition) process is performed on the interlayer insulating layer 30 on which the device protection layer 41 and the blocking layer 36 are formed to deposit a second oxide layer 46.

As shown in FIG. 5, the second oxide film 46 is formed with a curvature due to the groove 34 formed in the interlayer insulating film 30.

Then, isotropic etching is performed to maintain the shape of the second oxide layer 46, so that the microlens 50 is formed as shown in FIG. 6.

Thus, the microlens 50 is formed to include a portion of the interlayer insulating film 30.

The etching may be performed by performing a reactive ion etch process.

In this case, the microlens 50 may have a gap formed between the microlenses 50 to prevent a bridge or merge with a neighboring microlens.

The blocking layer 36 is positioned in the gap region between the microlens 50 formed at the same time as the microlens 50 is formed.

That is, as shown in FIG. 6, a plurality of adjacent microlenses 50 are formed in contact with the blocking layer 36.

In the present exemplary embodiment, since the blocking film 36 is formed at a position corresponding to the gap region of the microlens 50, when light enters the gap region of the microlens 50, the blocking film 36 reaches the blocking layer 36. do.

Therefore, the incident light to the photosensitive device 20 is prevented, so that the light not passing through the microlens 50 is not incident to the photosensitive device 20, thereby improving the light sensitivity of the image sensor.

In addition, the light incident between the gap regions of the microlens 50 is blocked by the blocking film 36 to block the generation of noise and crosstalk of the photodiode disposed on the semiconductor substrate 10 in advance, thereby preventing the image sensor. Can improve the quality.

Further, unlike forming a microlens by forming a pattern with a photoresist for forming a microlens and performing a reflow process, a microlens may be formed at the same time as an etching process, thereby freeing contamination by the photoresist. .

In addition, as the distance between the microlens 50 and the light sensing device 20 is shortened, the size of the image sensor may also be reduced.

The above-described embodiments are not limited to the above-described embodiments and drawings, and various substitutions, modifications, and changes can be made without departing from the technical spirit of the embodiments, having ordinary skill in the art. It will be obvious to him.

The embodiment may improve the reliability of the image sensor by blocking light incident to the gap region of the microlens to prevent crosstalk and noise.

Further, unlike forming a microlens by forming a pattern with a photoresist for forming a microlens and performing a reflow process, a microlens may be formed at the same time as an etching process, thereby freeing contamination by the photoresist. .

Claims (8)

delete delete delete Forming an interlayer insulating film including a lower wiring on a semiconductor substrate including a photosensitive device; Forming a photoresist pattern on a region of the interlayer insulating layer corresponding to the photosensitive device; Forming a groove in the interlayer dielectric layer by performing a first etching process on the interlayer dielectric layer using the photoresist pattern as a mask; Forming a blocking layer on the bottom surface of the groove and removing the photoresist pattern; Forming an oxide film on the interlayer insulating film having the blocking film formed on the bottom surface of the groove; And Performing a second etching process on the oxide film to form a microlens, And a part of the blocking layer is exposed by the second etching process. The method of claim 4, wherein The blocking film is formed in the gap region between the microlens manufacturing method of the image sensor. The method according to claim 4 or 5, The blocking film is a manufacturing method of an image sensor comprising a formed of any one or a stack of Ti, TiN, W. The method of claim 4, wherein The second etching process is a method of manufacturing an image sensor isotropically etched through the reaction ion etching process. The method of claim 4, wherein And the oxide film and the oxide film are formed of the same material.

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