KR20110075945A - Image sensor and method for manufacturing the same - Google Patents

Abstract

PURPOSE: An image sensor and a manufacturing method thereof are provided to improve efficiency of light by forming a light shielding layer in an empty space between metal lines selectively. CONSTITUTION: A plurality of photo diodes are formed per a unit pixel on a semiconductor substrate(100). A bottom insulation layer is formed on the semiconductor substrate. A first insulation layer(120) includes first metal lines(121) formed on the bottom insulation layer. The first insulation layer is arranged along the X direction of the photo diode. A first light shielding layer is arranged on the first insulation layer. The first light shielding layer is formed along the Y direction in an empty space between the first metal lines.

Description

Image sensor and manufacturing method thereof {IMAGE SENSOR AND METHOD FOR MANUFACTURING 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, and includes a charge coupled device (CCD) image sensor and a complementary metal oxide silicon sensor (CIS). Are distinguished.

The CMOS image sensor generates an image by sequentially detecting an electrical signal of each unit pixel by switching a photodiode and transistors in the unit pixel.

As the design rule of the image sensor is gradually reduced, the size of the unit pixel may be reduced, thereby reducing the light sensitivity.

Microlenses are formed on a color filter corresponding to a unit pixel in order to increase light sensitivity.

However, diffracted light scattering of light due to a plurality of wiring layers present in the optical path from the microlens to the photodiode may occur. Scattered light can be transmitted to adjacent pixels through the empty space between the wirings.

The scattered light may be reflected by the wiring to be returned or incident to adjacent pixels to cause crosstalk.

This phenomenon is more pronounced as the pixel size becomes smaller, because light interference increases as the pixel size decreases.

As a result, as the pixel size decreases, light scattering of the photodiode decreases due to scattering of light, which may cause a decrease in sensitivity of the image sensor.

On the other hand, the color filter array corresponding to the unit pixel may be divided into red, green and blue filters.

At this time, the light incident to the photodiodes corresponding to the color filters of the same color adjacent to each other should be the same, which causes an imbalance of the image by increasing or decreasing either side due to the irregular arrangement of the wiring lines.

The embodiment provides an image sensor and a method of manufacturing the same, which can selectively form a light blocking layer in an empty space between metal lines and improve light efficiency.

According to an exemplary embodiment, an image sensor includes: a plurality of photodiodes formed in unit pixels on a semiconductor substrate; A lower insulating layer formed on the semiconductor substrate; A first insulating layer aligned in the x-axis direction with respect to the photodiode and including first metal lines formed on the lower insulating layers corresponding to both sides of the photodiode so as not to cover the photodiode; And a first light blocking layer disposed on the first insulating layer so as not to cover the photodiode, and formed in a y-axis direction in a space between the first metal lines.

In another embodiment, a method of manufacturing an image sensor includes: forming a plurality of photodiodes for each pixel on a semiconductor substrate; Forming a lower insulating layer on the semiconductor substrate; Forming a first insulating layer including first metal lines on the lower insulating layer that is aligned in the x-axis direction with respect to the photodiode and does not cover the photodiode; And forming a first light blocking layer formed on the first insulating layer so as not to cover the photodiode, and having a y-axis direction in a space between the first metal lines.

In example embodiments, a light blocking layer may be formed in an empty space of a metal line formed in an upper region of a photodiode of a unit pixel to improve light sensitivity of an image sensor.

In particular, the light blocking layer may be formed by selectively implanting ions into the insulating layer so as not to cover the photodiode, and to propagate light to the photodiode of the pixel.

Accordingly, crosstalk and noise generation of the image sensor can be prevented and image characteristics can be improved.

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

In the description of the embodiments, where it is described as being formed "on / under" of each layer, it is understood that the phase is formed directly or indirectly through another layer. It includes everything.

1 is a cross-sectional view illustrating an image sensor according to an embodiment. 3 is a plan view illustrating the first wiring layer of FIG. 1. FIG. 5 is a plan view illustrating the second wiring layer of FIG. 1. 6 is a view showing the results of electromagnetic wave simulation (electromagnetic wave simulation) according to the wavelength of light in the image sensor and the general image sensor according to the embodiment.

According to an exemplary embodiment, an image sensor includes a plurality of photodiodes (PD1, PD2, PD3, and PD4) formed in a unit pixel on a semiconductor substrate 100; A lower insulating layer 110 formed on the semiconductor substrate 100; First insulation including first metal lines 121 formed on the lower insulation layer 110 corresponding to both sides of the photodiode so as to be aligned in the x-axis direction with respect to the photodiode and not to cover the photodiode. Layer 120; And a first light blocking layer 125 disposed on the first insulating layer 120 so as not to cover the photodiode, and formed in a y-axis direction in a space between the first metal lines 121.

The second insulating layer 130 including the second metal line 131 may be further formed on the first insulating layer 120.

The second metal lines 131 may be arranged in the y-axis direction with respect to the photodiode and disposed on the first insulating layer 120 corresponding to both sides of the photodiode so as not to cover the photodiode. .

A second light blocking layer 135 may be further formed in the second insulating layer 130 in the x-axis direction in a space between the second metal lines 131 so as not to cover the photodiode.

For example, the photodiodes may include a first photodiode PD1, a second photodiode PD2, a third photodiode PD3, and a fourth photodiode PD4.

The first to fourth photodiodes PD1, PD2, PD3, and PD4 may be disposed in a mesh or matrix form so as to be adjacent to each other.

A protective layer may be disposed on the second insulating layer 130.

The color filter 140, the planarization layer 150, and the microlens 160 may be further disposed on the passivation layer 140 to correspond to the first to fourth photodiodes PD1, PD2, PD3, and PD4. have.

As shown in FIG. 2, the rows formed by the first and second photodiodes PD1 and PD2 and the rows formed by the third and fourth photodiodes PD3 and PD4 are in a horizontal direction when the x-axis is referenced. Can be arranged parallel to each other.

The first metal line 121 may be disposed on both sides of the first and second photodiodes PD1 and PD2 based on the x-axis and disposed on both sides of the third and fourth photodiodes PD3 and PD4. have.

The first light blocking layer 125 may be disposed in an empty space in the y-axis direction of the first, second, third and fourth photodiodes PD3 and PD4.

That is, the first light blocking layer 125 may be disposed in the empty space between the first to fourth photodiodes PD1, PD2, PD3, and PD4 based on the y-axis direction.

When viewed in plan view, the first metal line 121 and the first light blocking layer 125 may have a shape surrounding all sides of the first to fourth photodiodes PD1, PD2, PD3, and PD4.

Accordingly, incident light may be incident on the photodiode of the corresponding unit pixel.

The first light blocking layer 125 may be an ion implantation layer.

For example, the first insulating layer 120 may be formed of an oxide film and have a first refractive index (n = 1.4 to 1.5).

The first light blocking layer 125 may be formed of a material having an atomic radius larger than that of the oxide film. The first light blocking layer 125 may have a second refractive index (1.6 to 2.0) greater than the first refractive index. For example, the first light blocking layer may be formed of an argon (Ar) element.

The first light blocking layer 125 may be metal.

For example, the first light blocking layer 125 may be formed of the same metal material as the first metal line M1.

Accordingly, the first light blocking layer 125 and the first metal line 121 may block light incident to the neighboring pixel and improve light sensitivity.

As shown in FIG. 4, when the y-axis is referenced, the rows formed by the first and third photodiodes PD1 and PD3 and the rows formed by the second and fourth photodiodes PD2 and PD4 are vertically aligned. Can be arranged parallel to each other.

The second metal line 131 may be disposed on both sides of the first to third photodiodes PD1PD3 on the y-axis, and disposed on both sides of the second and fourth photodiodes PD2 and PD4.

The second light blocking layer 135 may be disposed in an empty space in the x-axis direction of the first to fourth photodiodes PD1, PD2, PD3, and PD4.

That is, the second light blocking layer 135 may be disposed in the empty space between the first to fourth photodiodes PD1, PD2, PD3, and PD4 based on the x-axis direction.

When viewed in plan view, the second metal line 131 and the second light blocking layer 135 may have a shape surrounding all sides of the first to fourth photodiodes PD1, PD2, PD3, and PD4.

Accordingly, incident light may be incident on the photodiode of the corresponding unit pixel.

The second light blocking layer 135 may be an ion implantation layer.

For example, the second insulating layer 130 may be formed of an oxide film and have a first refractive index (n = 1.4 to 1.5).

The second light blocking layer 135 may be formed of a material having an atomic radius larger than that of the oxide film. The second light blocking layer 135 may have a second refractive index (1.6 to 2.0) greater than the first refractive index. For example, the second light blocking layer 135 may be formed of an argon (Ar) element.

The second light blocking layer 135 may be metal.

For example, the second light blocking layer 135 may be formed of the same metal material as the second metal line M2.

Accordingly, the second light blocking layer 135 and the second metal line 131 may block light incident to the neighboring pixel and improve light sensitivity.

FIG. 6A illustrates a simulation result of an electromagnetic wave (EMW) simulation by a general first metal line M1 and a second metal line M2. For example, the first metal line M1 is aligned with the x-axis, and the second metal line M2 is aligned with the y-axis.

As shown in FIG. 6A, light passing through the microlens and the color filter enters a neighboring pixel due to scattering of light by the first and second metal lines M1 and M2. You can confirm that

FIG. 6B is a result of an electromagnetic wave (EMW) simulation by the first metal line M1 and the second metal line M2 according to the embodiment. In an embodiment, the first metal line M1 is aligned with the x-axis, and the first light blocking layer 125 is formed in the empty space between the first metal lines M1. In addition, the second metal line M2 of the embodiment is aligned with the y-axis, and the second light blocking layer 135 is formed in the empty space between the second metal lines M2.

As shown in FIG. 6B, light passing through the micro lens and the color filter may enter the corresponding pixel by the first and second metal lines 131 and the first and second light blocking layers.

That is, the first and second metal lines 131 and the first and second light blocking layers 135 may be formed at upper portions of the first and second photodiodes PD1, PD2, PD3, and PD4. It is formed in the, can improve the crosstalk and noise characteristics.

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

1 and 2, a first metal line 121 is formed on a semiconductor substrate 100 on which first, second, third and fourth photodiodes PD1, PD2, PD3, and PD4 are formed. The first insulating layer 120 is formed.

An isolation layer STI is formed in the semiconductor substrate 100 to define an active region and a field region. The first to fourth photoelectric charges are generated in the active region of the semiconductor substrate 100 to receive light. Photo diodes PD1, PD2, PD3, and PD4 and a CMOS circuit (not shown) connected to the photodiodes to convert the received photocharges into electrical signals may be formed for each pixel.

The first to fourth photodiodes PD1, PD2, PD3, and PD4 may be formed in a matrix or mesh type. That is, the first to fourth photodiodes PD1, PD2, PD3, and PD4 may be adjacent to each other.

For example, based on the x-axis, one row formed by the first and second photodiodes PD1 and PD2 and one row formed by the third and fourth photodiodes PD3 and PD4 are in a horizontal direction. Can be arranged parallel to each other.

Based on the y-axis, one column formed by the first and third photodiodes PD1 and PD3 and one row formed by the second and fourth photodiodes PD2 and Pd4 are parallel to each other in the longitudinal direction. Can be arranged.

The lower insulating layer 110 is formed on the semiconductor substrate 100 including the first to fourth photodiodes PD1, PD2, PD3, and PD4. The lower insulating layer 110 may be an insulating layer before metal wiring, and the lower insulating layer 110 may include a contact plug connected to the metal wiring.

The first metal line 121 may be formed by depositing and patterning a metal on the lower insulating layer 110. The first insulating layer 120 may be formed by depositing an insulating layer on the first metal line 121 and then performing a planarization process.

The first metal line 121 may be formed in the x-axis direction so as not to cover the first to fourth photodiodes PD1, PD2, PD3, and PD4.

For example, the first metal line 121 may be formed on both sides of the first and second photodiodes PD1 and PD2 based on the x-axis. In addition, the first metal line 121 may be formed at both sides of the third and fourth photodiodes PD3 and PD4.

Unit pixels may be electrically connected to a circuit region (not shown) by the first metal line 121.

In this case, the first metal line 121 is not formed

Empty spaces are formed in regions corresponding to both sides of the first to fourth photodiodes PD1, PD2, PD3, and PD4 in the y-axis direction.

Referring to FIG. 3, a first light blocking layer 125 is formed on the first insulating layer 120 so as not to cover the first to fourth photodiodes PD1, PD2, PD3, and PD4.

The first light blocking layer 125 may be formed on the first insulating layer 120 coplanar with the first metal line 121.

The first light blocking layer 125 may be formed by selectively ion implantation into empty spaces corresponding to both sides of the first to fourth photodiodes PD1, PD2, PD3, and PD4 in the y-axis direction.

The first light blocking layer 125 may be formed of a material having a refractive index larger than that of the first insulating layer 120.

For example, the first light blocking layer 125 may be formed of a material having an atomic radius larger than that of the oxide film. The first light blocking layer 125 may be formed of Ar ions.

Accordingly, a first metal line 121 and a first light blocking layer 125 are formed on the first insulating layer 120 corresponding to the peripheral portions of the first to fourth photodiodes PD1, PD2, PD3, and PD4. This can be formed.

Accordingly, light incident on the first to fourth photodiodes PD1, PD2, PD3, and PD4 may be incident on the corresponding pixel without refraction to the adjacent pixel.

The refractive index of the first insulating layer 120 is about 1.4 to 1.5. In order to selectively block the incidence of light, the refractive index difference should be higher than 0.2. When the first light blocking layer 125 is selectively formed of an element such as argon having an atomic radius greater than that of the material forming the first insulating layer 120, the refractive index may be selectively increased, and light may be blocked.

The first light blocking layer 125 may be formed of the same metal as the first metal line 121.

The first light blocking layer 125 may be patterned at the same time when the first metal line 121 is formed.

The first metal line 121 and the first light blocking layer 125 may be formed of a metal, and light may be incident on the photodiode.

1 and 4, a second insulating layer 130 including a second metal line 131 on the semiconductor substrate 100 on which the first metal line 121 and the first light blocking layer 125 are formed. ) Is formed.

Meanwhile, an interlayer insulating layer (not shown) may be further formed on the first insulating layer 120 before forming the second insulating layer 130.

The second metal line 131 may be formed by depositing and patterning a metal on the first insulating layer 120. The second insulating layer 130 may be formed by depositing an insulating layer on the second metal line 131 and then performing a planarization process. Alternatively, the second metal line 131 may be formed by gap filling through a damascene process after forming an insulating layer.

The second metal line 131 may be formed in the y-axis direction so as not to cover the first to fourth photodiodes PD1, PD2, PD3, and PD4.

For example, the second metal line 131 may be formed at both sides of the first to third photodiodes PD1 and PD3 based on the y axis. In addition, the second metal lines 131 may be formed at both sides of the second and fourth photodiodes PD2 and PD4.

The surface of the second insulating layer 130 may have a region corresponding to both sides of the first to fourth photodiodes PD1, PD2, PD3, and PD4 in which the second metal line 131 is not formed in the x axis direction. Exposed and voids are formed.

Referring to FIG. 5, a second light blocking layer 135 is formed on the second insulating layer 130 so as not to cover the first to fourth photodiodes PD1, PD2, PD3, and PD4.

The second light blocking layer 135 may be formed by ion implantation into the second insulating layer 130 coplanar with the second metal line 131.

The second light blocking layer 135 may be formed by selectively ion implanting into empty spaces corresponding to both sides of the first to fourth photodiodes PD1, PD2, PD3, and PD4 in the x-axis direction.

The second light blocking layer 135 may be formed of the same material as the first light blocking layer 125.

The second light blocking layer 135 may have a higher refractive index than the second insulating layer 130.

For example, the second insulating layer 130 may be an oxide film and the second light blocking layer 135 may be formed of an Ar element.

A second metal line 131 and a second light blocking layer 135 may be formed on the second insulating layer 130 corresponding to the peripheral portion of the first to fourth photodiodes PD1, PD2, PD3, and PD4. Can be.

That is, all directions of the first to fourth photodiodes PD1, PD2, PD3, and PD4 may be surrounded by the second metal line 131 and the second light blocking layer 135.

Accordingly, light incident on the first to fourth photodiodes PD1, PD2, PD3, and PD4 may be incident on the corresponding pixel without refraction to the adjacent pixel.

The second light blocking layer 135 may be formed of the same metal as the first metal line 131.

The second light blocking layer 135 may be simultaneously patterned when the second metal line 131 is formed.

The second metal line 131 and the second light blocking layer 135 may be formed of metal, and light may be incident on the corresponding photodiode.

Referring to FIG. 1 again, a protective layer (not shown) is formed on the second insulating layer 130 and the color filters correspond to the first to fourth photodiodes PD1, PD2, PD3, and PD4, respectively. 140 and microlens 160 are formed.

In example embodiments, a light blocking layer may block light in an empty space of a metal line formed in an upper region of a photodiode of a unit pixel, thereby improving light sensitivity of an image sensor.

In particular, the light blocking layer may be formed by selectively implanting ions into the insulating layer so as not to cover the photodiode, and to propagate light to the photodiode of the corresponding pixel.

Accordingly, crosstalk and noise generation of the image sensor can be prevented and image characteristics can be improved.

The present invention is not limited to the described embodiments and drawings, and various other embodiments are possible within the scope of the claims.

1 is a perspective view illustrating a part of an image sensor according to an embodiment.

2 and 3 are plan views illustrating the first wiring layer in FIG. 1.

4 and 5 are plan views illustrating the second wiring layer in FIG. 1.

6 is a view showing the results of electromagnetic wave simulation (electromagnetic wave simulation) according to the wavelength of light in the image sensor and the general image sensor according to the embodiment.

Claims (20)

A plurality of photodiodes formed for each unit pixel on the semiconductor substrate; A lower insulating layer formed on the semiconductor substrate; A first insulating layer aligned in the x-axis direction with respect to the photodiode and including first metal lines formed on the lower insulating layers corresponding to both sides of the photodiode so as not to cover the photodiode; And And a first light blocking layer disposed on the first insulating layer so as not to cover the photodiode, and formed in a y-axis direction in a space between the first metal lines. The method of claim 1, The first light blocking layer is an image sensor formed of an ion implantation layer. The method of claim 2, And a second insulating layer aligned in the y-axis direction with respect to the photodiode and including second metal lines formed on the first insulating layer corresponding to both sides of the photodiode so as not to cover the photodiode. Image sensor. The method of claim 3, And a second light blocking layer disposed on the second insulating layer so as not to cover the photodiode, and formed in the x-axis direction in the space between the second metal lines. 5. The method of claim 4, The second light blocking layer is an image sensor formed of an ion implantation layer. 5. The method of claim 4, And the first and second insulating layers have a first refractive index, and the first and second light blocking layers have a second refractive index greater than the first refractive index. 5. The method of claim 4, And the first insulating layer is formed of an oxide film, and the first light blocking layer is formed of a material having an atomic radius larger than that of the oxide film. 5. The method of claim 4, The first and second light blocking layers are formed of argon (Ar) ions. 5. The method of claim 4, And a color filter and a micro lens formed on the second insulating layer corresponding to the photodiode. 5. The method of claim 4, The first and second light blocking layers are formed of metal. Forming a plurality of photodiodes for each unit pixel on the semiconductor substrate; Forming a lower insulating layer on the semiconductor substrate; Forming a first insulating layer including first metal lines on the lower insulating layer that is aligned in the x-axis direction with respect to the photodiode and does not cover the photodiode; And And forming a first light blocking layer formed on the first insulating layer so as not to cover the photodiode, and having a y-axis direction in a space between the first metal lines. The method of claim 11, The first light blocking layer is formed on both sides of the photodiode in the y-axis direction through a selective ion implantation process. The method of claim 12, The first insulating layer is formed of an oxide film, The first light blocking layer is formed by implanting argon (Ar) ions into the space between the first metal line. The method of claim 11, Forming a second insulating layer including second metal lines on the first insulating layer that is aligned in the y-axis direction with respect to the photodiode and does not cover the photodiode on both sides of the photodiode; Method of manufacturing an image sensor further comprising. The method of claim 14, And forming a second light shielding layer formed on the second insulating layer so as not to cover the photodiode, and having a x-axis direction in a space between the second metal lines. The method of claim 15, The second light blocking layer is formed in an empty space corresponding to both sides of the photodiode in the x-axis direction through a selective ion implantation process. The method of claim 15, The second insulating layer is formed of an oxide film, And the second light blocking layer is formed by injecting argon (Ar) ions into the space between the second metal lines. The method of claim 14, And the first and second insulating layers are formed at a first refractive index, and the first and second light blocking layers are formed at a second refractive index greater than the first refractive index. The method of claim 15, And forming a color filter and a micro lens on the second insulating layer corresponding to the photodiode. The method of claim 15, The first light blocking layer is patterned at the same time when forming the first metal line, And the second light blocking layer is patterned and formed at the same time when the second metal line is formed.

Images