JP2003204055A - Solid-state imaging device and method of manufacturing the same - Google Patents

Abstract

(57) Abstract: A solid-state imaging device capable of realizing an improvement in S / N ratio and an improvement in image quality by promoting reduction of interface states by hydrogenation and reducing dark current. And a method for producing the same. A CMO having main wiring layers (41b, 42b) containing aluminum for pixel selection and signal propagation in a pixel portion.
In the S-type solid-state imaging device, each main wiring layer 41b, 42
barrier metal 41a, 41c, 42 for preventing reaction b
Tungsten nitride is used for the adhesion layers 31a and 32a of the conductive layers 31b and 32b made of tungsten or the like for filling the contact holes a and 42c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device used for an image input device such as a digital camera, a video camera, an image reader, etc., and a manufacturing method thereof.

[0002]

2. Description of the Related Art Image input devices such as digital cameras, video cameras, and image readers are equipped with a CCD (Charge Coupl
ed Device) A solid-state image sensor such as an image sensor or a non-CCD type image sensor such as a CMOS image sensor is provided, where optical image information is converted into an electric signal, and various signals are converted into the electric signal. It is processed and displayed on a display or recorded on a recording medium.

In order to obtain a high-performance solid-state image pickup device, the light-collecting efficiency and photoelectric conversion efficiency of each pixel on the sensor portion are increased to enhance the sensitivity, and the random noise depending on the dark current and the amplifier, and the fixed pattern noise. Is required to be low and the S / N ratio is high.

In the CMOS image sensor which uses the CMOS technology such as memory and logic, the wiring technology of the CMOS element is also used for the selection line of each pixel and the signal propagation line. In the wiring technology of the CMOS element, aluminum or aluminum containing copper or silicon is generally used as the wiring material of each layer.

This aluminum wiring forms an alloy layer at the junction with silicon, polysilicon, or tungsten polycide, so-called alloy spike that destroys the pn junction inside the silicon bulk, or disconnection failure due to sucking up silicon or tungsten. cause.

In order to prevent this and stabilize the junction resistance, titanium (Ti) or titanium nitride (TiN) is used.
There is widely used a structure in which a so-called barrier metal made of is sandwiched between a joint portion of aluminum wiring and silicon or the like.

With the miniaturization of elements, contact holes for connecting multi-layered wirings have also been miniaturized, and CVD (Chemical Vapor Deposition) is used to supplement the step coverage of aluminum wiring formed by sputtering. A technique of filling a contact hole with tungsten is widely used.

Since this tungsten is difficult to grow on an insulating film such as silicon oxide and has poor adhesion, titanium (Ti) or titanium nitride (Ti) is used as an adhesion layer.
N) is widely used.

In the CMOS image sensor, by applying the CMOS wiring technique as described above, for pixel selection for selecting pixels formed in the pixel portion and for signal propagation for reading out signal charges accumulated in each pixel. A wiring and a contact connected to the wiring are formed.

[0010]

As described above, in order to improve the S / N ratio of the image sensor, it is necessary to reduce noise due to dark current. As a means for reducing the dark current, it is necessary to terminate the dangling bond with hydrogen in order to reduce the interface state at the interface between silicon and the silicon oxide film. Therefore, heat treatment is performed in a gas containing hydrogen (H ₂ ) or a film containing an NH group is formed.

However, titanium, which is used as a barrier metal for the wiring of the CMOS image sensor, has the function of adsorbing hydrogen, as is commonly used for hydrogen storage alloys, and is used to reduce the interface level. It hinders the above-mentioned hydrotreatment. As a result, CMO
The dark current of the S image sensor could not be reduced, leading to deterioration of image quality.

The present invention has been made in view of the above circumstances, and its object is to improve the S / N ratio by promoting the reduction of the interface state by hydrogenation and reducing the dark current. An object of the present invention is to provide a solid-state imaging device capable of realizing improvement in image quality and a manufacturing method thereof.

[0013]

In order to achieve the above object, a solid-state image pickup device of the present invention has a substrate in which a plurality of pixels are provided, and a contact hole is filled with a conductive layer to form a contact via a contact. A solid-state imaging device having a wiring layer connected to the pixel, wherein the wiring layer has a barrier layer for preventing reaction of a main wiring material, and the contact is in close contact with the conductive layer embedded in the contact hole. And an adhesion layer capable of ensuring the property, and the barrier layer and the adhesion layer are formed of a material containing tungsten nitride.

The wiring layer contains aluminum as the main wiring material.

The conductive layer contains tungsten.

It further has a hydrogen-containing film formed in the upper layer of the substrate and containing hydrogen which can be captured by defects in the substrate.

In the above solid-state image pickup device of the present invention, the barrier layer and the adhesion layer are made of a material containing tungsten nitride having no hydrogen storage property, and no metal having a high hydrogen storage property is used. Hydrogenation of the substrate is not hindered when diffusing into the substrate. Further, the tungsten nitride employed in the present invention, by containing nitrogen, functions as a barrier layer for preventing reaction of the main wiring material and as an adhesion layer for ensuring adhesion of the conductive layer to the contact hole. have.

In order to achieve the above object, in the method for manufacturing a solid-state image pickup device of the present invention, a plurality of pixels are formed on a substrate, a contact layer is filled with a conductive layer to form a contact, and the contact is formed through the contact. A method of manufacturing a solid-state imaging device for forming a wiring layer connected to the pixel, comprising the steps of forming a barrier layer for preventing reaction of a main wiring material in the formation of the wiring layer, and forming the contact,
And a step of forming an adhesion layer capable of ensuring the adhesion of the conductive layer embedded in the contact hole, and in forming the barrier layer and the adhesion layer, the barrier layer and the adhesion layer are formed of a material containing tungsten nitride.

In forming the wiring layer, a material containing aluminum is used as the main wiring material.

In forming the contact, the conductive layer containing tungsten is buried in the contact hole through the adhesion layer.

In forming the barrier layer and the adhesion layer, tungsten nitride is formed by sputtering.

After the step of forming the wiring layer, there is a step of heat treatment in a gas atmosphere containing hydrogen.

After the step of forming the wiring layer, a step of forming a hydrogen-containing film containing hydrogen that can be captured by a defect of the substrate on the substrate in the pixel portion, and a step of performing heat treatment are further included. Have.

According to the above-described method for manufacturing a solid-state image pickup device of the present invention, a material containing tungsten nitride having no hydrogen storage property is used for the barrier layer and the adhesion layer, and no metal having high hydrogen storage property is used. Therefore, when hydrogen is diffused into the substrate later, hydrogenation of the substrate is not hindered.
Further, the tungsten nitride employed in the present invention, by containing nitrogen, functions as a barrier layer for preventing reaction of the main wiring material and as an adhesion layer for ensuring adhesion of the conductive layer to the contact hole. have.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a solid-state image pickup device and a method of manufacturing the same according to the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the configuration of a CMOS type solid-state image pickup device according to this embodiment. The solid-state imaging device 1 shown in FIG. 1 includes a photodiode (that is, a pn) that performs photoelectric conversion.
Junction type photo sensor) 2 and a pixel for selecting, for example, M
Vertical selection switch element 4 consisting of an OS transistor
And a control electrode (gate electrode) of the vertical selection switch element 4 for each row, and an imaging region in which a plurality of unit pixels 5 configured by a read switch element 3 including, for example, a MOS transistor, are arranged in a matrix. To the vertical selection line SVL connected in common with
(ΦV1, ... φVm, ... φVm + k, ...)
And the vertical signal line VL to which the main electrodes of the read switch elements 3 are connected in common for each column.
And a read pulse line RL connected to the main electrode of the vertical selection switch element 3 for each column, and a horizontal switch element 7 composed of, for example, a MOS transistor having main electrodes connected to the vertical signal line VL and the horizontal signal line HL. A horizontal scanning circuit 8 connected to the control electrode of the horizontal switch element 7 and the read pulse line RL, and an amplifier 9 connected to the horizontal signal line HL.

In each unit pixel 5, one main electrode of the read switch element 3 is connected to the photo sensor 2, and the other main electrode is connected to the vertical signal line VL. Also,
One main electrode of the vertical selection switch element 4 is connected to the control electrode of the read switch element 3, the other main electrode is connected to the read pulse line RL, and the control electrode thereof is connected to the vertical select line SVL. ing.

From the horizontal scanning circuit 8 to each horizontal switching element 7
Horizontal scanning pulse φH (φH1, ... φH
n, ... φHn + 1, ...) is supplied, and a horizontal read pulse φH is supplied to each read pulse line RL.
^R (φH ^R 1, ... φH ^R n, ... φH ^R n + 1,
...) is supplied.

The basic operation of the solid-state image pickup device 1 is as follows. Vertical scanning pulse φVm from vertical scanning circuit 6
And the vertical selection switch element 4 which has received the read pulse φH ^R n from the horizontal scanning circuit 8 receives those pulses φV.
A pulse of the product of m and φH ^R n is generated, and the control electrode of the read switch element 3 is controlled by this pulse of the product to read the signal charge photoelectrically converted by the photosensor 2 to the vertical signal line VL. This signal charge is output to the horizontal signal line HL through the horizontal switch element 7 controlled by the horizontal scanning pulse φH from the horizontal scanning circuit 8 during the horizontal video period,
The signal is converted into a signal voltage by the amplifier 9 connected to this and output.

In the above example, an example in which two transistors are included in the unit pixel has been described. However, the present invention is not limited to this, and there are various types such as one having five transistors in the unit pixel. .

FIG. 2 is a sectional view showing the photosensor 2 and its upper layer structure. As shown in FIG. 2, for example, n is formed in the active region of the p-type semiconductor substrate 10 pixel-separated by the element isolation insulating film 10 made of silicon oxide or the like.
An n-type semiconductor region 12 containing a type impurity is formed, and a photosensor 2 is formed by forming a pn junction between the n-type semiconductor region 12 and the p-type semiconductor substrate 10.

An n-type semiconductor region 12 'formed at the same time as the n-type semiconductor region 12 of the photosensor 2 is formed in another portion of the semiconductor substrate 10 in which pixels are separated,
A gate insulating film 13 made of silicon oxide or the like is formed on the semiconductor substrate 10 between the n-type semiconductor regions 12 and 12 ′.
And a read switch element 3 formed of an nMOS transistor formed by laminating a gate electrode 14 having a polycide structure. In a region (not shown), a vertical selection switch element composed of a MOS transistor and other elements are formed on the semiconductor substrate 10 in which pixels are separated.

A first interlayer insulating film 21 made of silicon oxide or the like is formed so as to cover the photosensor 2 and the read switch element 3, and the gate electrode 14 and the n-type are formed on the first interlayer insulating film 21. A contact hole reaching the semiconductor region 12 'is formed. Although not shown, contact holes are also formed in regions that need to be connected to the vertical selection switch element and other elements.

The inner surface of the contact hole formed in the first interlayer insulating film 21 is covered with tungsten nitride (W
The contact layer 31a made of N) is formed, and the conductive layer 31b made of tungsten (W) is embedded in the contact hole via the contact layer 31a. Contact 3
1 is formed.

A first layer wiring 41 is formed on the first interlayer insulating film 21 so as to connect to the first contact 31. The first layer wiring 41 is arranged in order from the lower layer.
A barrier metal 41a made of tungsten nitride and a main wiring layer 41 made of aluminum containing copper or silicon
b and a barrier metal 41c made of tungsten nitride. The barrier metal 41a is made up of the aluminum forming the main wiring layer 41b and the first contact 3
It has a role of preventing the reaction with the tungsten forming the first conductive layer 31b. Similarly, the barrier metal 41c also has a role of preventing a reaction between aluminum forming the main wiring layer 41b and tungsten used for the conductive layer of the upper contact.

First layer wiring 41 and first interlayer insulating film 2
A second interlayer insulating film 22 made of silicon oxide or the like is formed so as to cover No. 1 and the surface of the second interlayer insulating film 22 is flattened.

The upper layer structure of the second interlayer insulating film 22 is basically formed by repeating a contact forming layer and a wiring layer. In this embodiment, a two-layer wiring is shown as an example. That is, a third interlayer insulating film 23 made of, for example, silicon oxide is formed on the entire surface covering the second interlayer insulating film 22, and a desired portion of the third interlayer insulating film 23 is contacted. A hole is formed.

An inner surface of the contact hole formed in the third interlayer insulating film 23 is covered, and an adhesion layer 32a made of tungsten nitride (WN) is formed in the same manner.
A conductive layer 32b made of tungsten (W) is embedded in the contact hole via the adhesion layer 32a,
The contact layer 32a and the conductive layer 32b form a second contact 32.

A second layer wiring 42 is formed on the third interlayer insulating film 23 so as to be connected to the second contact 32. The second layer wiring 42 is arranged in order from the lower layer.
A barrier metal 42a made of tungsten nitride and a main wiring layer 42 made of aluminum containing copper or silicon
b and a barrier metal 42c made of tungsten nitride.

Second layer wiring 42 and third interlayer insulating film 2
A third interlayer insulating film 24 made of silicon oxide or the like is formed so as to cover 3 and the surface of the fourth interlayer insulating film 24 is flattened.

In this way, multilayer wiring is formed on the photosensor 2, the read switch element 3, and the other transistors formed on the semiconductor substrate 10. In the present embodiment, as an example, the two-layer wiring including the first-layer wiring 41 and the second-layer wiring 42 is shown, but the present invention is not limited to this.

Fourth interlayer insulating film 24 whose surface is flattened
A protective film 50 made of, for example, silicon nitride or the like is formed thereon.

Although not shown, the upper layer of the protective film 50 is
An on-chip color filter is formed, and an on-chip lens made of a light transmissive material such as a negative photosensitive resin is formed on the on-chip color filter. The on-chip color filters are red (R), green (G),
It is colored in blue (B), and in the complementary color system, for example,
Cyan (Cy), magenta (Mg), yellow (Y
e), green (G), or the like.

Next, a method of manufacturing the solid-state image pickup device according to this embodiment will be described with reference to FIGS.

First, as shown in FIG. 3A, the necessary elements are formed on the semiconductor substrate 10 by using the CMOS technique as in the case of forming a general CMOS image sensor. For example, after the element isolation insulating film 11 is formed by selective oxidation for pixel isolation on the semiconductor substrate 10 made of p-type silicon or the like, the semiconductor substrate 1 in the active region where the unit pixel is to be formed.
0 to form a gate insulating film 13 by thermal oxidation, and then form a polycrystalline silicon film, a tungsten silicide (WSi) film, etc., and pattern this by dry etching to form the polycide structure of the read switch element. The gate electrode 14 is formed. At this time,
Gate electrodes of elements such as vertical selection switch elements (not shown) are also formed at the same time. After the gate electrode 14 is formed, n is formed in the drain region of the read switch element and the region where the photosensor is to be formed using the gate electrode 14 as a mask.
A type impurity, for example, arsenic (As) is ion-implanted to form the n-type semiconductor regions 12 and 12 '. As a result, the photosensor 2 having a pn junction is formed, and the n-type semiconductor region 12 ′ serving as the drain of the read switch element 3 is formed. At this time, the source / drain regions of elements such as vertical selection switch elements (not shown) are also formed at the same time.

Next, as shown in FIG. 3B, the entire surface of the semiconductor substrate 10 is covered with TEOS (tetraethylorthos).
LPCVD (Low Pressure Chemica) using ilicate
l Vapor Deposition) method is used to deposit silicon oxide to form the first interlayer insulating film 21.

Next, as shown in FIG. 3C, a resist pattern (not shown) having an opening in a region where a contact hole is formed is formed by photolithography technique, and the anisotropic dry mask is used as a mask. By performing the etching, the first interlayer insulating film 21
Contact holes C11 and C12 reaching the gate electrode 14 and the n-type semiconductor region 12 'are formed. At this time, the semiconductor substrate 1 is formed in other regions than those shown in the drawing.
A contact hole is formed in a region where a contact with the element formed in 0 is to be formed.

Next, as shown in FIG. 4D, the entire surface of the semiconductor substrate 10 is covered, and tungsten nitride is deposited by reactive sputtering to form the adhesion layer 31a.
At this time, the conditions for forming the tungsten nitride film are as follows: target: tungsten, gas flow rate: mixed gas of Ar and N ₂ (N ₂ ratio is in the range of 30 to 60%), pressure: 0.133.
~ 1.33 Pa (1-10 mTorr), Power: 10
The film is formed within the range of 0 to 1000 W and the film thickness of 10 to 100 nm. That is, in the gas flow rate ratio, the larger the N ₂ ratio, the smaller the metal composition ratio and thus the resistance, and the smaller the N ₂ ratio, the larger the metal composition ratio and the smaller the resistance. The optimum flow rate ratio is set in consideration of. Further, since the pressure affects the in-plane uniformity of the film thickness and the composition of the film to be formed, and also the stress on the substrate, the optimum pressure is set within the above range. Further, since the power influences the film forming rate and the stress on the substrate, the optimum power is set within the above range in consideration of these factors. The film thickness depends on the diameter of the contact hole, but basically, if the film thickness of the adhesion layer is too large, the contact hole is blocked, so the film thickness is set to a small value within the range that functions as the adhesion layer. It is preferable. In addition, as a suitable example, gas flow rate: Ar / N
₂ = 60/40 sccm, pressure: 0.266 Pa (2 m
Torr), power: 500 W, and film thickness 40 nm.

Next, as shown in FIG. 4 (e), the adhesion layer 3
Tungsten (W) is deposited on the entire surface of 1a by a CVD method to form a conductive layer 31b. At this time, an example of CVD conditions for tungsten is gas: Ar / N ₂ / H
₂ / WF ₆ = 2200/300/500 / 75scc
m, temperature: 450 ° C., pressure can be about 1040 Pa.

Next, as shown in FIG. 4F, the entire surface is etched back until the first interlayer insulating film 21 is exposed,
Adhesion layer 31a other than in the contact holes C11, C12
And the conductive layer 31b is removed. As a result, the first contact 31 including the adhesion layer 31a and the conductive layer 31b is formed in the contact holes C11 and C12.
At this time, as an example of etch back conditions, gas: S
F ₆ = 50 sccm, RF power: 150 W, pressure:
It can be about 1.33 Pa.

Next, as shown in FIG. 5G, the entire surface of the semiconductor substrate 10 is covered and tungsten nitride is deposited by reactive sputtering to form a barrier metal 41a. As the film forming conditions of the tungsten nitride at this time, target: tungsten, gas flow rate: mixed gas of Ar and N ₂ (N ₂ ratio is in the range of 30 to 60%), pressure, similar to the forming conditions of the adhesion layer 31 a. : 0.133 to 1.33
Pa (1 to 10 mTorr), power: 100 to 100
A film is formed within a range of 0 W and a film thickness of 10 to 100 nm. Here, it is basically the same as that described for the adhesion layer, but in the gas flow rate ratio, the smaller the N ₂ ratio, the smaller the barrier property to the aluminum wiring. Set the gas flow rate ratio in consideration. Further, it is considered that at least about 10 nm is necessary to fulfill the function as a barrier metal. In addition, as a preferable example, the same conditions as those of the tungsten nitride forming the adhesion layer, gas flow rate: Ar / N ₂ = 60/40 sccm, pressure: 0.2
66 Pa (2 mTorr), power: 500 W, film thickness 4
0 nm is mentioned.

Next, as shown in FIG. 5 (h), aluminum containing copper and silicon is deposited by sputtering on the entire surface of the barrier metal 41a to form a main wiring layer 41.
b is formed.

Next, as shown in FIG. 5 (i), the entire surface of the main wiring layer 41b is covered and tungsten nitride is deposited by reactive sputtering to form a barrier metal 41c. The film forming conditions for the barrier metal 41c at this time are the same as those described for the barrier metal 41a.

Next, as shown in FIG. 6J, a resist pattern (not shown) having a pattern of the first layer wiring is formed on the barrier metal 41a, the main wiring layer 41b, and the barrier metal 41c by a photolithography technique. Then, anisotropic dry etching is performed using the resist pattern as a mask to form the first-layer wiring 41 including the barrier metals 41a and 41c and the main wiring layer 41b.

Next, as shown in FIG. 6 (k), a high density plasma enhanced CV (High Density Plasma enhanced CV
D: A silicon oxide film is deposited by the HDP-CVD method, and then CMP (Chemical Mechanical Polishin) is performed.
by the method g) until the first layer wiring 41 is exposed,
By eliminating the step due to the first-layer wiring 41, the second interlayer insulating film 22 having a flattened surface is formed.

Next, as shown in FIG. 7 (l), the silicon oxide film is removed from the silicon oxide film by the LPCVD method using TEOS in the same manner as the contact forming process shown in FIGS. 3 (b) to 4 (f). Is formed, a contact hole is formed in the third interlayer insulating film 23, and the adhesion layer 3 made of tungsten nitride is formed by sputtering.
2a is formed, the conductive layer 32b made of tungsten is formed by the CVD method, and the entire surface is etched back.
A second contact 32 is formed, which includes an adhesion layer 32a and a conductive layer 32b buried in the contact hole of the third interlayer insulating film 23.

Next, as shown in FIG. 7 (m), a barrier metal made of tungsten nitride is formed by sputtering and etching in the same manner as the wiring forming process shown in FIGS. 5 (g) to 6 (k). 42a, a main wiring layer 42b made of aluminum to which copper and silicon are added, and a second layer wiring 42 of a predetermined pattern made of a barrier metal 42c made of tungsten nitride are formed, and HDP-CVD is performed.
A silicon oxide film is deposited by the CMP method and the surface is polished by the CMP method to form a fourth interlayer insulating film 24 having a flattened surface.

As the subsequent steps, when further multilayer wiring is formed, the contact forming step shown in FIG. 7L and the wiring forming step shown in FIG. 7M are repeated as necessary to form the final wiring. After that, a protective film 50 is formed by depositing a silicon nitride film by a plasma CVD method.

Subsequently, annealing (hereinafter referred to as hydrogenation treatment) is performed at a temperature of 200 ° C. to 350 ° C. for a time of 30 minutes to 180 minutes. The gas used in this hydrogenation treatment is 100% hydrogen gas, a mixed gas of hydrogen gas and nitrogen gas, or the like. This enables plasma CVD
Film 50 made of silicon nitride and formed by the method
Contains a large amount of hydrogen, the hydrogen contained in the protective film 50 is diffused by the heat treatment, and the dangling bond existing in the interface between the substrate 10 and the first interlayer insulating film 21 in the photosensor 2 is present. Alternatively, the dangling bond existing at the interface between the semiconductor substrate 10 and the gate insulating film 13 under the gate electrode 14 of the read switch element 3 is eliminated to reduce the interface state between the semiconductor substrate 10 and the insulating film. . Note that hydrogenation is performed not only after forming a protective film formed of a silicon nitride film by plasma CVD as described above, but also by annealing in a gas containing hydrogen before forming the protective film. May be.

Subsequently, for example, an on-chip color filter is formed on the protective film 50, and an on-chip lens is formed on the on-chip color filter. When using a dyeing method as a method of forming an on-chip color filter,
A sensitizer is added to a polymer such as casein and applied, and exposure, development, dyeing and fixing are repeated for each color. Alternatively, the on-chip color filter may be formed by using a dispersion method, a printing method, an electrodeposition method, or the like. The on-chip lens has a lens material such as a light-transmitting resin such as a negative photosensitive resin formed on the entire surface, and a lens-shaped resist pattern having a predetermined curvature is formed on the lens material. It can be formed by processing the lens material by etching using the pattern as a mask.

As described above, the solid-state image pickup device according to this embodiment shown in FIG. 2 can be manufactured.

In the present embodiment described above, the hydrogenation treatment is performed by performing heat treatment in an atmosphere containing hydrogen before or after forming the protective film 50, and as a result, as described above, the protective film 50 is formed. Of hydrogen contained in the photosensor 2 and hydrogen in the external atmosphere are diffused toward the substrate by the heat treatment, and dangling bonds existing at the interface between the substrate 10 and the insulating film 21 in the photosensor 2 and the gate electrode 14 of the read switch element 3. The interface state between the semiconductor substrate 10 and the insulating film is reduced by eliminating the dangling bond existing at the interface between the semiconductor substrate 10 and the gate insulating film 13 below. In the present embodiment, since tungsten nitride having no hydrogen storage property is used for the barrier metal of the wiring and the adhesion layer, and titanium (Ti) having high hydrogen storage property is not used at all, this hydrogen diffuses to the substrate 10. At this time, since hydrogenation of the substrate 10 is not hindered, the reduction of the interface state due to hydrogenation is promoted.

Further, in the present embodiment, the wirings 41 and 42 are
As described above, the tungsten nitride (WN) used for the barrier metals 41a, 41c, 42a, and 42c of the above contains the nitrogen, thereby preventing the reaction of aluminum constituting the main wiring layer equivalent to that of the conventional titanium nitride. It has been confirmed that it has a barrier property to protect the material and has workability equivalent to that of titanium nitride. Further, although tungsten deposited by the CVD method as the conductive layers 31b and 32b of the contacts 31 and 32 does not adhere well to the surface of the insulating film, tungsten nitride deposited by sputtering is used as the adhesion layer. It was confirmed that the adhesion was improved and that the adhesion layer had a function equivalent to that of conventional titanium nitride.

As described above, according to this embodiment, titanium (Ti) and titanium nitride (TiN) which adsorb hydrogen are adsorbed.
It is possible to manufacture a CMOS type solid-state imaging device without using the above, and to reduce the dark current of the CMOS type solid-state imaging device without hindering the hydrogenation treatment for reducing the interface state. As a result, it is possible to improve the S / N ratio and the image quality of the solid-state imaging device.

The present invention is not limited to the above description of the embodiments. For example, in the present embodiment, an example of forming a film by ordinary sputtering has been described as a method of manufacturing the tungsten nitride forming the barrier metal or the adhesion layer.
In order to prevent the film thickness deposited on the bottom of the contact hole from decreasing with the increase of the aspect ratio and improve the film deposition on the bottom of the contact hole, long-distance sputtering that draws the orthogonal component of sputtered particles, collimated sputtering, etc. Can also be used. Besides, various modifications can be made without departing from the scope of the present invention.

[0066]

According to the present invention, the S / N ratio is improved by promoting the reduction of the interface state by hydrogenation and reducing the dark current.
It is possible to improve the ratio and the image quality.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a configuration of a CMOS type solid-state imaging device according to an embodiment.

FIG. 2 is a cross-sectional view showing an example of a photosensor of the solid-state imaging device according to the present embodiment and an upper layer structure thereof.

FIG. 3 is a cross-sectional view after forming a contact hole in the manufacture of the solid-state imaging device according to the present embodiment.

FIG. 4 is a cross-sectional view after the formation of the first contact in the manufacture of the solid-state imaging device according to the present embodiment.

FIG. 5 is a cross-sectional view after deposition of a conductive layer to be the first-layer wiring in the manufacture of the solid-state imaging device according to the present embodiment.

FIG. 6 is a cross-sectional view after forming a second interlayer insulating film in the manufacture of the solid-state imaging device according to the present embodiment.

FIG. 7 is a cross-sectional view after formation of a fourth interlayer insulating film in the manufacture of the solid-state imaging device according to the present embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Solid-state imaging device, 2 ... Photo sensor, 3 ... Read-out switch element, 4 ... Vertical selection switch element, 5 ... Unit pixel, 6 ... Vertical scanning circuit, 7 ... Horizontal switch element, 8 ...
Horizontal scanning circuit, 9 ... Amplifier, 10 ... Semiconductor substrate, 11 ...
Element isolation insulating film, 12, 12 '... N-type semiconductor region, 13
... gate insulating film, 14 ... gate electrode, 21 ... first interlayer insulating film, 22 ... second interlayer insulating film, 23 ... third interlayer insulating film, 24 ... fourth interlayer insulating film, 31 ... first , 31a ... Adhesion layer, 31b ... Conductive layer, 32 ... Second contact, 32a ... Adhesion layer, 32b ... Conductive layer, 41 ... First layer wiring, 41b ... Main wiring layer, 41a, 41c ... Barrier metal, 42 ... Second layer wiring, 42b ... Main wiring layer, 42
a, 42c ... Barrier metal, 50 ... Protective film, SVL ... Vertical selection line, VL ... Vertical signal line, RL ... Read pulse line, HL ... Horizontal signal line, C11, C12 ... Contact hole.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 21/90 CAF term (reference) 4M118 AA05 AB01 BA14 CA03 CA34 EA01 FA06 FA28 GC08 GC09 GD04 5C024 CX32 CY47 5F033 HH04 HH09 HH28 HH34 JJ19 JJ34 KK01 KK09 KK34 MM07 MM08 MM13 NN06 PP16 PP22 QQ08 QQ09 QQ10 QQ11 QQ16 QQ37 QQ39 QQ48 QQ73 RR04 RR06 SS04 SS13 SS15 TT02 VV06 XX14 XX20

Claims (10)

[Claims] 1. A solid-state imaging device comprising: a substrate provided with a plurality of pixels; and a wiring layer connected to the pixels through a contact formed by burying a conductive layer in a contact hole. Has a barrier layer for preventing reaction of the main wiring material, the contact has an adhesion layer capable of ensuring adhesion of the conductive layer embedded in the contact hole, the barrier layer and the adhesion layer The solid-state imaging device is made of a material containing tungsten nitride. 2. The solid-state imaging device according to claim 1, wherein the wiring layer contains aluminum as the main wiring material. 3. The solid-state imaging device according to claim 1, wherein the conductive layer contains tungsten. 4. The solid-state imaging device according to claim 1, further comprising a hydrogen-containing film that is formed on an upper layer of the substrate and contains hydrogen that can be captured by defects in the substrate. 5. A method of manufacturing a solid-state imaging device, comprising forming a plurality of pixels on a substrate, forming a contact by embedding a conductive layer in a contact hole, and forming a wiring layer connected to the pixel via the contact. And a step of forming a barrier layer for preventing a reaction of a main wiring material in the formation of the wiring layer, and an adhesion layer capable of ensuring the adhesion of the conductive layer embedded in the contact hole in the formation of the contact. And a step of forming the barrier layer and the adhesion layer, wherein the barrier layer and the adhesion layer are formed of a material containing tungsten nitride. 6. The method for manufacturing a solid-state imaging device according to claim 5, wherein in forming the wiring layer, a material containing aluminum is used as the main wiring material. 7. The method for manufacturing a solid-state imaging device according to claim 5, wherein in forming the contact, the conductive layer containing tungsten is embedded in the contact hole via the adhesion layer. 8. The method of manufacturing a solid-state imaging device according to claim 5, wherein tungsten nitride is deposited by sputtering in the formation of the barrier layer and the formation of the adhesion layer. 9. The method for manufacturing a solid-state imaging device according to claim 5, further comprising a step of performing heat treatment in an atmosphere of a gas containing hydrogen after the step of forming the wiring layer. 10. After the step of forming the wiring layer, a step of forming, on the substrate in the pixel portion, a hydrogen-containing film containing hydrogen that can be captured by defects in the substrate, and a step of performing heat treatment. The method for manufacturing a solid-state imaging device according to claim 5, further comprising: