KR100907157B1 - Image sensor and method for fabricating the same - Google Patents

Abstract

Embodiments relate to an image sensor and a method of manufacturing the same. The image sensor may include a semiconductor substrate having unit pixels formed thereon, an insulating layer formed on the semiconductor substrate and having first to third color filter regions corresponding to the unit pixels, and a metal wiring connected to the unit pixel. And a microlens formed on the metallization layer in correspondence with the unit pixel and the metallization layer including the unit pixel. According to the embodiment, a color filter array formed as a separate layer using a color filter is formed on an insulating layer by ion implantation to increase the light transmittance by reducing the number of layers, and to reduce the sensitivity by reducing the distance between the microlens and the photodiode. Can be improved.

Color filter, ion implantation

Description

Image sensor and manufacturing method thereof {IMAGE SENSOR AND METHOD FOR FABRICATING THE SAME}

Embodiments relate to an image sensor and a method of manufacturing the same.

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).

CMOS image sensors are devices that digitize light with IMAGING technology. 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.

The structure of the CMOS image sensor is briefly divided into a light receiving unit, a filter unit, a sensor unit, and a circuit unit. The key to imaging technology is to filter the incoming light and digitize the image without losing any light.

1 is a cross-sectional view showing a conventional image sensor.

In the image sensor illustrated in FIG. 1, an insulating layer 15 is formed on a pixel array substrate 10 on which a unit pixel including a photodiode 11 is formed, and a metal wire is formed on the insulating layer 15. A metal wiring layer 20 formed of a multilayer is formed, and a protective layer 30 and a color filter array layer 40 are formed on the metal wiring layer 20, and the color filter array layer 40 is formed on the metal filter layer layer 40. The microlens 50 corresponding to the unit pixel is formed.

The conventional image sensor adopts a structure in which many layers are stacked for a wiring process, and the distance between the microlens 50 and the photodiode 11 is increased by a separate color filter layer, thereby reducing sensitivity. have.

The embodiment provides a thin image sensor and a method of manufacturing the same by forming a color filter array of an image sensor through an ion implantation in an insulating layer.

The image sensor may include a semiconductor substrate having unit pixels formed thereon, an insulating layer formed on the semiconductor substrate and having first to third color filter regions corresponding to the unit pixels, and a metal wiring connected to the unit pixel. And a microlens formed on the metallization layer in correspondence with the unit pixel and the metallization layer including the unit pixel.

The method of manufacturing an image sensor according to the embodiment may include forming unit pixels including a photodiode on a semiconductor substrate, forming an insulating layer on the semiconductor substrate, and selectively performing a primary ion implantation process on the insulating layer. Forming a first color filter region, selectively performing a secondary ion implantation process on the insulating layer, forming a second color filter region, selectively performing a tertiary ion implantation process on the insulation layer, and performing a third color Forming a filter region and forming a metal wiring on the insulating layer.

The embodiment has the effect of realizing a thin image sensor by reducing the thickness of the image sensor by forming the color filter array of the image sensor through the ion implantation in the insulating layer.

The embodiment has the effect of increasing the transmittance of light by reducing the number of layers by forming a color filter array provided as a separate layer in the insulating layer using a color filter in the insulating layer by ion implantation.

The embodiment has the effect of improving the sensitivity by reducing the distance between the micro lens and the photodiode.

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

In the description of the embodiments, where described as being formed "on / over" of each layer, the on / over may be directly or through another layer ( indirectly) includes everything formed.

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.

2 to 6 are cross-sectional views illustrating a manufacturing process of an image sensor according to an embodiment.

Although not illustrated, a field oxide film for electrical insulation between devices is formed on the semiconductor substrate 100, and a pixel region and a peripheral circuit region are formed on the active region.

The circuit region is formed by forming an N type well or a P type well and applying and patterning polysilicon and a metal material. A gate spacer is formed on the gate electrode, and ion implantation is performed to form a source, a drain, and a sensing node of the transistor.

As shown in FIG. 2, a photodiode 101 is formed in a unit pixel by implanting ions into the semiconductor substrate 100 in the pixel region.

As shown in FIG. 3, an insulating layer 110 is formed on the semiconductor substrate 100 on which the transistor and the photodiode 101 are formed. A first photoresist pattern 181 is formed on the insulating layer 110.

The first photoresist pattern 181 forms a photoresist film through a spin coating process, and the photoresist film is patterned and formed by a photo process including an exposure process and a developing process.

The first color filter region 111 is formed in the insulating layer 110 by performing a primary ion implantation process on the semiconductor substrate 100 using the first photoresist pattern 181 as a mask.

The first ion implantation process may include a semiconductor containing at least one of ions containing at least one of a metal element consisting of iron (Fe), copper (Cu), cobalt (Co), manganese (Mn), and antimony (Sb). Inject in 100.

The first color filter area 111 may be formed at a position corresponding to the photodiode 101.

Subsequently, when the first photoresist pattern 181 is removed and heat treated, the first color filter region 111 is formed on the insulating layer 110 with a first depth a.

For example, the first color filter area 111 may be a red color filter area.

As shown in FIG. 4, a second photoresist pattern 182 is formed on the insulating layer 110 on which the first color filter region 111 is formed.

The second photoresist pattern 182 forms a photoresist film through a spin coating process, and the photoresist film is patterned and formed by a photo process including an exposure process and a developing process.

The second color filter region 112 is formed on the insulating layer 110 by performing a secondary ion implantation process on the insulating layer 110 using the second photoresist pattern 182 as a mask.

The secondary ion implantation process includes a semiconductor substrate having ions containing at least one of metal elements consisting of iron (Fe), copper (Cu), cobalt (Co), manganese (Mn), and antimony (Sb) with a predetermined energy. Inject in 100.

The second color filter area 112 corresponds to a photodiode 101 that is different from the photodiode 101 corresponding to the first color filter area 111.

Subsequently, when the second photoresist pattern 182 is removed and then heat treated, the second color filter area 112 is formed on the insulating layer 110 having a second depth b.

For example, the second color filter area 112 may be a green color filter area. The second depth b is shallower than the first depth a.

As shown in FIG. 5, a third photoresist pattern 183 is formed on the semiconductor substrate 100 on which the first color filter region 111 and the second color filter region 112 formed independently of each other are formed. .

The third photoresist pattern 183 forms a photoresist film through a spin coating process, and the photoresist film is patterned and formed by a photo process including an exposure process and a developing process.

The third color filter region 113 is formed on the insulating layer 110 by performing a third ion implantation process on the insulating layer 110 using the third photoresist pattern 183 as a mask.

In the tertiary ion implantation process, the semiconductor substrate contains ions containing at least one of metal elements consisting of iron (Fe), copper (Cu), cobalt (Co), manganese (Mn), and antimony (Sb) with a predetermined energy. Inject in.

The third color filter region 113 corresponds to a photodiode 101 different from the photodiode 101 corresponding to the first and second color filter regions 111 and 112.

Thereafter, when the third photoresist pattern 183 is removed and then heat treated, the third color filter region 113 is formed on the insulating layer 110 having a third depth c.

For example, the third color filter area 113 may be a blue color filter area. The third depth c is shallower than the second depth b.

The color filter array may be formed on the insulating layer 110 through the ion implantation process as described above.

Therefore, by forming the color filter array of the image sensor through the ion implantation in the insulating layer 110, it is possible to implement a thin image sensor by reducing the thickness of the image sensor, color filter array provided as a separate layer using a color filter Can be formed in the insulating layer by ion implantation to reduce the number of layers, thereby increasing the light transmittance.

Sensitivity may be improved by reducing the distance between the microlens to be formed later and the photodiode.

The depth of the first color filter region 111, which is a red color filter among the first to third color filter regions 111, 112, and 113, is the deepest and the third color filter region 113, which is a blue color filter. The depth is the shallowest, which is the relative thickness considering the transmittance of each color.

For example, when the depth of the third color filter region 113 is 2000 microns, the depth of the second color filter region 112 is 4000 microns, and the depth of the first color filter region 111 is deeply formed near the photodiode. do.

As shown in FIG. 6, a metal wiring layer 120 including a metal wiring 121 and a plurality of interlayer insulating films on the insulating layer 110 on which the first to third color filter regions 111, 112, and 113 are formed. ) Is formed.

The metal line 121 is intentionally disposed to be connected to a power line, a signal line, and a pixel area so as not to block light incident to the pixel area.

In addition, a pad (not shown) is formed when the uppermost metal wiring 121 of the metal wiring layer 120 is formed. The pad may include a metal having low electrical resistance, such as aluminum or an aluminum alloy, and the pad may be electrically connected to the pixel.

Although not shown, Ti or TiN may be formed as a conductive barrier layer on the metal line 121 and the pad.

A protective layer 130 is formed on the metal wiring layer 120 including the metal wiring 121 and the pad to protect the device from external moisture or scratches. For example, the protective layer 130 may be a silicon oxide film, a silicon nitride film, or a stacked structure of the films.

The microlens 150 is formed on the passivation layer 130 corresponding to each of the unit pixels.

In the process of forming the microlens 150, the microlens photoresist film is coated on the protective layer 130 through a spin process, and the photoresist film is selectively exposed and developed, and then each of the first to the first A photoresist pattern is formed on the color filter region. Thereafter, a reflow process may be performed to form the dome-shaped micro lens having a convex shape.

In an embodiment, the color filter region is formed in the insulating layer 110 formed on the semiconductor substrate 100. However, the present invention is not limited thereto, and any interlayer between the semiconductor substrate 100 and the microlens 150 may be formed. The color filter region may be formed by ion implantation into the insulating film.

The embodiment has the effect of realizing a thin image sensor by reducing the thickness of the image sensor by forming a color filter array of the image sensor through the ion implantation in the insulating layer.

The embodiment has the effect of increasing the transmittance of light by reducing the number of layers by forming a color filter array provided as a separate layer in the insulating layer using a color filter in the insulating layer by ion implantation.

The embodiment has the effect of improving the sensitivity by reducing the distance between the micro lens and the photodiode.

Although described above with reference to the embodiments, which are merely examples and are not intended to limit the present invention. Those skilled in the art to which the present invention pertains are not exemplified above without departing from the essential characteristics of the present invention. It will be appreciated that many variations and applications are possible. For example, each component specifically shown in the embodiment of the present invention can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

1 is a cross-sectional view showing a conventional image sensor.

2 to 6 are cross-sectional views illustrating a manufacturing process of an image sensor according to an embodiment.

Claims (6)

A semiconductor substrate on which unit pixels are formed; An insulating layer formed on the semiconductor substrate; First to third color filter regions in which metal ions are implanted into the insulating layer at predetermined depths corresponding to the unit pixels, and have different implantation depths; A metal wiring layer formed on the insulating layer and including a metal wire electrically connected to the unit pixel; And And a micro lens formed on the metallization layer corresponding to the unit pixels. The method of claim 1, The first to third color filter regions may include ions including at least one of metal elements including iron (Fe), copper (Cu), cobalt (Co), manganese (Mn), and antimony (Sb) in the insulating layer. And an ion implantation region formed by implantation. The method of claim 1, The first color filter region is a red color filter, the deepest ion implantation depth is formed near the photodiode, the third color filter region is a blue color filter, the image sensor, characterized in that the shallowest ion implantation depth. Forming unit pixels including a photodiode on a semiconductor substrate; Forming an insulating layer on the semiconductor substrate; Selectively performing a first ion implantation process on the insulating layer to form a first color filter region; Selectively performing a secondary ion implantation process on the insulating layer to form a second color filter region different from the depth of the first color filter region; Selectively performing a third ion implantation process on the insulating layer to form a third color filter region different from a depth of the first and second color filter regions; And And forming a metal wiring layer on the insulating layer, the metal wiring layer including metal wires electrically connected to the unit pixels. The method of claim 4, wherein The first to third ion implantation process is characterized by implanting ions containing at least one of a metal element consisting of iron (Fe), copper (Cu), cobalt (Co), manganese (Mn), antimony (Sb). The manufacturing method of the image sensor made into. The method of claim 4, wherein And heat treatment after the first to third order ion implantation processes to form different depths of the first to third color filter regions.

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