KR101053729B1 - Image sensor and its manufacturing method - Google Patents

Abstract

An image sensor according to an embodiment includes a substrate having a first metal wire; Bonding silicon on the substrate, the bonding silicon comprising a first impurity region and a second impurity region; A first interlayer insulating film formed on the bonding silicon; A first contact plug penetrating the bonding silicon and connected to the first metal wire; A second interlayer insulating film formed on the first interlayer insulating film; A second contact plug penetrating the second interlayer insulating layer and connected to the first impurity region; And a second metal wire formed on the second interlayer insulating layer and connected to the second contact plug, wherein an insulating layer for isolation with the first impurity region is formed on one side of the first contact plug. It is characterized by being.

According to the image sensor of the embodiment, in the photodiode region constituting the unit pixel, more effective isolation can be achieved between the first impurity regions, and contact with the contact plug can be precisely made for the second impurity regions.

Image sensor

Description

Image sensor and method for manufacturing the same {Image sensor and method for manufacturign thesame}

The embodiment discloses an image sensor and a method of manufacturing the same.

In general, an image sensor is a semiconductor device that converts an optical image into an electrical signal, and is generally classified into a charge coupled device (CCD) and a CMOS (Complementary Metal Oxide Silicon) image sensor.

The CMOS image sensor forms a photodiode and a MOS transistor in a unit pixel, and sequentially detects an electrical signal of each unit pixel in a switching manner to implement an image.

The conventional CMOS image sensor manufacturing process involves a chemical mechanical polishing process for forming a multilayer including a plurality of metal lines and an insulating layer after photodiode formation.

This causes a decrease in light sensitivity due to an increase in the distance from the photodiode to the color filter or the like and an increase in bad pixels due to an increase in defects.

An embodiment of the present invention is a logic chip consisting of an image chip for forming a color filter array and a micro lens after forming a photodiode using two chips, a driver IC for driving the same, and a logic array for providing additional functions. The present invention is to provide an image sensor and a method of manufacturing the same that can be three-dimensional integration of the image chip and logic chip using a single pad.

In addition, by eliminating a plurality of metal lines on the top of the photodiode, by reducing the distance between the photodiode and the micro lens, the optical path is dramatically reduced, and thereby an image sensor and a method of manufacturing the same are proposed. do.

The embodiment proposes a manufacturing method for effectively performing insulation and contact between photodiode regions constituting a unit pixel, for example, between p + regions of each photodiode in a bonding silicon including the photodiode region. A method of realizing insulation and a method in which a contact between an n + region of a photodiode and a contact plug can be effectively implemented.

An image sensor according to an embodiment includes a substrate having a first metal wire; Bonding silicon on the substrate, the bonding silicon comprising a first impurity region and a second impurity region; A first interlayer insulating film formed on the bonding silicon; A first contact plug penetrating the bonding silicon and connected to the first metal wire; A second interlayer insulating film formed on the first interlayer insulating film; A second contact plug penetrating the second interlayer insulating layer and connected to the first impurity region; And a second metal wire formed on the second interlayer insulating layer and connected to the second contact plug, wherein an insulating layer for isolation with the first impurity region is formed on one side of the first contact plug. It is characterized by being.

In addition, the manufacturing method of the image sensor of the embodiment comprises the steps of preparing a substrate on which the first metal wiring is formed; Bonding the top surface silicon of the substrate to form bonding silicon; Forming a first impurity region and a second impurity region in the bonding silicon; Forming a first interlayer insulating film on the bonding silicon; Etching a portion of the first interlayer insulating film to expose a portion of the surface of the bonding silicon; Performing an anisotropic etching process on the bonding silicon; Depositing an oxide film on the bonding silicon and on the first interlayer insulating film; Etching the oxide film so that a portion of the first metal wire is exposed; Forming a first contact plug connected with the first metal wire; And forming a second contact plug penetrating the first interlayer insulating film.

According to an embodiment of the present invention, bonding silicon is etched by wet etch when forming a contact plug penetrating the photodiode region, thereby reducing the number of times of plasma etching and causing defects in the substrate or photodiode region. Can reduce the number of cases.

In addition, in the photodiode region constituting the unit pixel, more effective isolation may be achieved between the first impurity regions, and contact with the contact plug may be precisely formed on the second impurity regions.

Hereinafter, with reference to the accompanying drawings for the present embodiment will be described in detail. However, the scope of the idea of the present invention may be determined from the matters disclosed by the present embodiment, and the idea of the invention of the present embodiment may be performed by adding, deleting, or modifying components to the proposed embodiment. It will be said to include variations.

In the following description, the word 'comprising' does not exclude the presence of other elements or steps than those listed.

1 is a diagram illustrating a configuration of an image sensor according to an exemplary embodiment of the present invention, and FIG. 2 is a diagram illustrating a configuration in which insulation and contact between photodiode regions are performed according to an exemplary embodiment of the present invention.

For reference, the description of the present invention will be described with reference to a part of the pixel region in which the photodiode is formed, and the logic region in which the lower wiring and the upper wiring are formed may be formed on one side of the pixel region, but specifically, It is not shown.

First, referring to FIG. 1, the image sensor of the embodiment includes a substrate 100 provided with a first metal wiring 101, and c-Si is cleaved to form computational inequalities such as transistors. Bonding silicon 120 is formed on the substrate 100 by bonding to the substrate 100.

A photodiode composed of a plurality of impurity regions is formed in the bonding silicon 120, and the photodiode includes a first impurity region 121 formed on an upper side of the bonding silicon 120 and the bonding. The second impurity region 121 formed on the lower side of the silicon 120 is included. For example, the photodiode may have a region in which n + conductive impurities are implanted in the lower side of the bonding silicon 120 and a region in which p + conductive impurities are implanted in the upper side of the bonding silicon 120. Can be.

Here, whether the photodiode in the bonding silicon 120 uses an electron or a hole as an electrical signal may be variously applied according to the embodiment.

In this regard, the photodiode shown in FIG. 1 forms a p + region on the upper side of the silicon and an n + region on the lower side of the silicon, using electrons as a signal when light is received and the n + region. The electrons gathered to the surface are moved through the contact plug and the metal line. On the contrary, it can be seen that when holes are used as signals, the formation of impurities will be different.

In the bonding silicon 120, a first contact plug 160 is formed in a region between photodiodes of each pixel region, and a first impurity region of the photodiode is formed on some side surfaces of the first contact plug 160. An insulating film 140 for insulating between 121 is formed, and the insulating film 140 is not formed in a region adjacent to the second impurity region 122 of the photodiode.

That is, the insulating layer 140 plays a role for isolation between the first impurity regions 121 of the photodiode, and the contact by the first contact plug 160 is performed between the second impurity regions 122. It is not formed on the side of the second impurity region 122 as much as possible.

In addition, an oxide film 131 and a nitride film 132 are sequentially stacked on the bonding silicon 120 including a photodiode having a plurality of impurity regions, and the oxide film 131 and the nitride film ( A second contact plug 180 for contacting the first impurity region 121 of the photodiode penetrates through 132, and an interlayer insulating layer 170 for interlayer insulation is formed on the nitride film 132.

If the oxide film 131 or the nitride film 132 formed on the bonding silicon 120 is a first interlayer insulating film, the interlayer insulating film 170 formed on the nitride film 132 may be referred to as a second interlayer insulating film. Can be.

In addition, a second metal wire 190 for electrical connection with the second contact plug 180 is formed on the second interlayer insulating layer 170.

Although not shown, a passivation layer may be further formed on the second metal wire 190, a color filter may be formed on the passivation layer, and light may be received on the color filter. Microlenses are formed.

On the other hand, in the image sensor according to an embodiment of the present invention, isolation and contact between each photodiode constituting the unit pixel should be performed, which will be described with reference to FIG. do.

2 shows that each photodiode constituting the unit pixel is formed on both sides of the first contact plug 160, and the photodiode has a first impurity region in order to generate holes or electrons as a signal upon receiving light. And a second impurity region 122.

As in the above example, in the case of using electrons as a signal, a first impurity region 121 into which a p + type impurity is implanted is formed inside the bonding silicon 120, and the first impurity region 121 is formed. Under the formation position, the second impurity region 122 into which the n + type impurity is implanted is formed.

When light is received, electrons generated in the photodiode are transferred to the first metal wire 101 through the second impurity region 122 and the first contact plug 160. As a result, an electrical signal is transmitted according to light reception.

However, isolation should be effectively performed between the first impurity regions 121 of each of the photodiodes constituting the unit pixel.

Therefore, as an isolation film formed around the first contact plug 140, the insulating layer 140 is formed around the first impurity region 121 and is formed on the second impurity region 122. Do not form in adjacent areas.

Particularly, the insulating layer 140 is partially formed below the oxide layer 131 which is a part of the first interlayer insulating layer for effective isolation. As a result, the insulating layer 140 is positioned in the lower region of the oxide layer 131. The first surface 141 is provided.

In addition, the insulating layer 140 is provided in a shape in which the thickness thereof gradually decreases from the first impurity region 121 to the second impurity region 122, thereby providing isolation and first separation between the first impurity regions. The contact between the impurity regions is effectively made.

If isolation is not properly performed between the first impurity regions in the photodiodes of the unit pixels, as shown in FIG. 15, the first impurity region may be directly connected to the contact plug. In addition, when the contact between the second impurity regions is not properly performed, as shown in FIG. 14, the second impurity region may not be connected to the contact plug.

In the image sensor according to the exemplary embodiment of the present invention, the second impurity region is contacted to the contact plug by the formation of the insulating layer, and the first impurity region is isolated to not directly contact the contact plug.

According to an embodiment of the present invention, the uniformity guaranteed image sensor is contacted with the n + region of the photodiode at the bottom of the contact plug and with the p + region of the photodiode at the top of the contact plug, as shown in FIG. 13. Isolation is performed correctly.

The method of manufacturing the image sensor as described above will be described in detail.

3 to 10 are views for explaining a manufacturing method of an image sensor according to an embodiment, FIG. 11 is a view showing an image photographing a configuration corresponding to FIG. 6, and FIG. 12 is a configuration corresponding to FIG. 7. Is a view showing the image taken.

First, referring to FIG. 3, the substrate 100 including the first metal wiring 101 is prepared, and c-Si is cleaved on the substrate 100 so that the computing unit is configured. Bonding to (100) to form a bonding silicon (120).

In addition, a process of forming a photodiode in the bonding silicon 120 is performed, and a first impurity region 121 in which impurities of a first conductivity type are injected into the bonding silicon 120 and a second conductivity The second impurity region 122 into which the impurities of the type are implanted is formed.

The first impurity region 121 is formed on the inside of the bonding silicon 120, and the second impurity region 122 is formed under the first impurity region 121. An n− impurity region or a depletion layer may be formed in the region between the first impurity region 121 and the second impurity region 122.

Next, referring to FIG. 4, an oxide film 131 and a nitride film 132 are deposited as a first interlayer insulating film on the bonding silicon 120 including the photodiode.

As the first interlayer insulating film, the oxide film 131 and nitride film 132 in can be formed either only one, and the oxide film 131, to form a SiH ₄ in a thickness of 1000Å the nitride film 132 is also 1000Å It can be formed in thickness.

Next, referring to FIG. 5, a photoresist (not shown) is coated on the nitride layer 132, and the photoresist is patterned to form an insulating layer for isolation between the first contact plug and the impurity region of the photodiode. Part of the nitride film 132 is exposed.

Then, the nitride film 132 and the oxide film 131 are etched by using the patterned photoresist as an etching mask, and as shown in the figure, for the region where the first contact plug and the insulating film are to be formed. A portion of the bonding silicon 120 is exposed.

Next, referring to FIG. 6, an anisotropic etch process is performed on the bonding silicon 120 to which a portion of the nitride layer 132 and the oxide layer 131 are exposed.

For example, dip treatment is performed for about 2 to 8 seconds in a KOH solution at 80 ° C. In this case, anisotropic etching occurs in the [111] direction of the silicon at the silicon surface (the [100] direction). Therefore, in the dip treatment process, a solution capable of generating anisotropic etching in the [111] direction of the silicon is used, an example of which is described as a KOH solution.

As the anisotropic etching process is performed, as illustrated in FIG. 6, a triangular or pyramid-shaped hole 135 is formed in the bonding silicon 120. Here, the hole 135 may be formed in a pyramid shape, because part of the substrate 100 may be exposed by the hole 135 by the anisotropic etching.

In particular, by the anisotropic etching process, the lower part of the lower surface of the oxide film 131 is exposed, that is, the lower surface of the remaining oxide film 131 is larger than the upper surface of the bonding silicon 120. do.

In FIG. 11, a diagram illustrating a photograph having such a configuration is disclosed. A hole having a very small size may be formed to expose a portion of the substrate 100.

Next, referring to FIG. 7, a process of depositing an oxide layer 140 inside the bonding silicon 120 and on the nitride layer 132 is performed. SiO ₂ may be used as the oxide layer 140.

Here, the oxide film 140 may be confused with the oxide film 131 serving as the first interlayer insulating film. However, the oxide film 140 may be easily identified through reference numerals described along with the names of the components.

Meanwhile, in depositing the oxide film 140 inside the bonding silicon 120 and on the nitride film 132, the oxide film 140 may be deposited to a thickness of about 800 μm.

A portion of the hole 135 formed in the bonding silicon 120 is filled by the deposition of the oxide layer 140, and a drawing of a photographic image thereof is attached to FIG. 12.

Next, referring to FIG. 8, an etching process is performed on the oxide film 140 formed in the bonding silicon 120 and on the nitride film 132, and the etching process of the oxide film 140 is performed by an etch back process. Etching is carried out to a uniform thickness. The etching process of the oxide layer 140 is performed until the substrate 100 positioned below the bonding silicon 120 and the first metal wiring 101 formed in the substrate 100 are exposed.

That is, the first metal wiring 101 is exposed by an etch back process or the like.

By the etching process of the oxide layer 140, a contact hole 150 in which a contact plug for contact with the first metal wire 101 is located is provided.

In addition, an etching process for removing the oxide film 140 formed on the nitride film 132 may be further performed, and such an oxide film removing process is not a necessary process.

Next, referring to FIG. 9, a first contact plug 160 is formed in the contact hole 150 formed in the bonding silicon 120 and the substrate 100. The first contact plug 160 may be formed by gap-filling a metal material such as tungsten, and then performing a planarization process, as in various known techniques.

Next, referring to FIG. 10, an insulating film is deposited on the nitride film 132 and the first contact plug 160 to form a second interlayer insulating film 170.

After the photoresist is applied and patterned on the second interlayer insulating layer 170, the second interlayer insulating layer 170 and the first interlayer insulating layer 132 and 131 are etched to form a second contact plug 180. A hole is formed, and a second contact plug 180 is formed in the contact hole.

In particular, the second contact plug 170 is formed to be connected to the first impurity region 121 in the photodiode region of the bonding silicon 120. This is to apply a reverse bias to the photodiode.

In addition, a second metal wire 190 to be electrically connected to the second contact plug 180 is formed on the second interlayer insulating layer 170. For the formation of the second metal wire 190, various known techniques may be applied, and thus a detailed description thereof will be omitted.

Although not shown, a process for forming a protective film may be further performed on the second metal wire 190, and further, a process of forming a color filter layer on the protective film, and a photoresist applied on the color filter layer to form a micro The process of forming the lens is further performed.

By this process, the image sensor according to the embodiment of the present invention is manufactured in the form as shown in FIG.

According to an embodiment of the present invention, bonding silicon is etched by wet etch when forming a contact plug penetrating the photodiode region, thereby reducing the number of times of plasma etching and causing defects in the substrate or photodiode region. Can reduce the number of cases.

In addition, in the photodiode region constituting the unit pixel, more effective isolation may be achieved between the first impurity regions, and contact with the contact plug may be precisely formed on the second impurity regions.

1 is a view showing the configuration of an image sensor according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating in detail a configuration in which insulation and contact between photodiode regions are performed according to an embodiment of the present invention; FIG.

3 to 10 are views for explaining a manufacturing method of the image sensor according to the embodiment.

FIG. 11 is a view showing an image of a configuration corresponding to FIG. 6. FIG.

FIG. 12 is a view showing an image photographing a configuration corresponding to FIG. 7. FIG.

13 is a view showing an image showing an insulating film and a contact plug formed in accordance with an embodiment of the present invention.

14 and 15 are views for exemplarily showing a case where a failure occurs in the lower part and the upper part of the contact plug.

Claims (11)

A substrate having a first metal wiring; Bonding silicon on the substrate, the bonding silicon comprising a first impurity region formed at an upper side and a second impurity region formed at a lower side thereof; A first interlayer insulating film formed on the bonding silicon; A first contact plug penetrating the bonding silicon and connected to the first metal wire; A second interlayer insulating film formed on the first interlayer insulating film; A second contact plug penetrating the second interlayer insulating layer and connected to the first impurity region; A second metal wire formed on the second interlayer insulating layer and connected to the second contact plug; And And a color filter layer and a micro lens formed on the second metal wire. And an insulating film formed on one side of the first contact plug for isolation with the first impurity region. The method of claim 1, A portion of the insulating film is formed to contact a portion of a lower surface of the first interlayer insulating film. The method of claim 1, And the first interlayer insulating film includes an oxide film formed on the bonding silicon and a nitride film formed on the oxide film. The method of claim 1, The insulating film is formed between the first contact plug and the first impurity region, And the second impurity region is in contact with a portion of the first contact plug. The method of claim 1, The first impurity region inside the bonding silicon is made of p + type impurity, and the second impurity region is made of n + type impurity. Preparing a substrate on which the first metal wiring is formed; Bonding silicon to the top surface of the substrate to form bonding silicon; Forming a first impurity region formed above the bonding silicon and a second impurity region formed below; Forming a first interlayer insulating film on the bonding silicon; Etching a portion of the first interlayer insulating film to expose a portion of the surface of the bonding silicon; Performing an anisotropic etching process on the bonding silicon; Depositing an oxide film on the bonding silicon and on the first interlayer insulating film; Etching the oxide film so that a portion of the first metal wire is exposed; Forming a first contact plug connected with the first metal wire; And And forming a second contact plug penetrating the first interlayer insulating film. The method of claim 6, The forming of the second contact plug may include forming a second interlayer insulating film on the first interlayer insulating film, and then etching a portion of the second interlayer insulating film and the first interlayer insulating film, and forming the second interlayer insulating film and the first interlayer insulating film. And a second contact plug penetrating the interlayer insulating film. The method of claim 7, wherein And after forming the second contact plug, forming a second metal wire on the second interlayer insulating layer to be electrically connected to the second contact plug. The method of claim 6, The forming of the second contact plug may include etching the first interlayer insulating layer to expose a portion of the bonding silicon in which the first impurity region is formed. The method of claim 6, The performing of an anisotropic etching process on the bonding silicon may include performing anisotropic etching on the [111] direction of silicon. 11. The method of claim 10, The anisotropic etching process is a method of manufacturing an image sensor, characterized in that the dip treatment process using a KOH solution.

Images