JPH06132508A - Solid-state image sensing element and manufacture thereof - Google Patents

Abstract

PURPOSE:To reduce smear and optical black false signal and prevent the generation of metallic spike by forming a metallic film constituting a light-shielding film by using a metallic material to suppress the generation of silicon nodule and forming a metallic film constituting a wiring film by using a metal to suppress generation of metallic. spike. CONSTITUTION:An aluminum film 9 forming a light-shielding film contains 0-0.5wt.% silicon. An aluminum film 10 forming a wiring film contains 0.5-1.2wt.% silicon. The film 9 has a low silicon content, so it is hard to generate silicon nodules. On the other hand, the film 10 has a high silicon content, so it is hard to generate aluminum spikes. Therefore, any smear and optical black false signal due to the silicon nodules of the light-shielding film and also the aluminum spikes can be reduced and prevented from being generated on the wiring film in a peripheral circuit as well.

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, and more particularly, to a solid-state image pickup device having an aluminum film which forms a light-shielding film for shielding the light except for the light-receiving part in the image pickup region and an aluminum film which forms a wiring film for peripheral circuits. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Generally, a solid-state image pickup device has a structure as shown in FIG. In the drawing, 1 is a semiconductor substrate, which is roughly divided into an imaging region 2 and a peripheral circuit 3.
The imaging region 2 is composed of an effective pixel portion 4 in which effective pixels are present, and an optical black portion 5 in which pixels are shielded from the surface and light does not enter.

Reference numeral 6 is a light receiving element for photoelectric conversion, which constitutes a pixel. Reference numeral 7 denotes a diffusion layer which forms, for example, a source and a drain of a transistor of the peripheral circuit, and 8a denotes a vertical transfer electrode, which is made of polycrystalline silicon. 8b is a silicon gate electrode of the above transistor. The interlayer film and the passivation film are not shown for convenience. 9 is a light-shielding film made of aluminum,
The image pickup area is covered except for the portion where the effective pixels are formed. In the effective pixel portion 4, the light is prevented from entering the transfer register to eliminate smear, and in the optical black portion 5, the light receiving element itself forming the pixel is provided. It blocks the entry of light into the optical black level signal.

Reference numeral 10 denotes an aluminum wiring film, which is in contact with a diffusion layer which forms a source and a drain of a transistor in the peripheral circuit. Then, conventionally, the aluminum film 10 forming the wiring film and the aluminum film 9 forming the light-shielding film are formed.
And were simultaneously formed of the same material. The material was specifically aluminum containing 1 wt% of silicon. The reason why the aluminum film containing 1 wt% of silicon is formed in this manner is to prevent a spike of aluminum toward the diffusion layer 7 side due to melting of silicon in the contact portion of the aluminum film 10 forming the wiring film. . Reference numeral 11 indicates a transfer register.

[0005]

By the way, in the conventional solid-state image pickup device, the light-shielding property of the light-shielding film 9 made of aluminum is deteriorated, smear occurs in the effective pixel portion 4, and optical black in the optical black portion 5. There was a problem that a false signal was generated. This is because when 1 wt% of silicon is contained in the aluminum film, silicon in aluminum is deposited, silicon nodules are generated, and light is transmitted therethrough due to the low light-shielding property of silicon nodules. To do.

That is, after forming an aluminum film forming a light-shielding film and a wiring film, a forming annealing (temperature 30
However, if silicon is present in the aluminum film, the silicon nodules 12 may be formed by the growth of the silicon during the annealing. The silicon nodule 12 has a poor light shielding property. Therefore, FIG.
As shown in FIG. 6A, the silicon nodules 12 above the vertical transfer electrodes 8 in the effective pixel area cause smear, and as shown in FIG. 6B, the silicon nodules 12 on the light receiving element 6 of the optical black 5 are formed. Causes an optical black false signal and is not preferable.

Therefore, it has been attempted to reduce the silicon content rate of the aluminum film to less than 1 wt%. However, if this is done, a spike will occur in the aluminum film forming the wiring film of the peripheral circuit, and therefore even if a spike occurs. The depth of the diffusion layer 7 must be increased so as not to hinder the operation, which not only hinders miniaturization and high integration, but also increases the parasitic capacitance of the transistor. Therefore, it is not a good idea to reduce the silicon content. As described above, conventionally, there is a trade-off relationship between preventing the generation of silicon nodules and preventing the generation of aluminum spikes.

The present invention has been made to solve such a problem, and has an aluminum film that forms a light-shielding film that shields light except for the light-receiving portion in the image pickup region, and an aluminum film that forms a wiring film for peripheral circuits. In the solid-state imaging device, it is possible to prevent generation of smear and silicon nodules that cause optical black spurious signals in the aluminum film that forms the light-shielding film, and the aluminum film that forms the wiring film of the peripheral circuit causes deterioration of transistor characteristics. The purpose is to prevent spikes from occurring.

[0009]

According to another aspect of the present invention, there is provided a solid-state image pickup device, wherein an aluminum film forming a light-shielding film is formed of an aluminum material which suppresses generation of silicon nodules, and an aluminum film forming a wiring film prevents generation of aluminum spikes. It is characterized in that it is formed of an aluminum material which is suppressed. A solid-state image pickup device according to a second aspect is the solid-state image pickup device according to the first aspect, wherein the aluminum film forming the light-shielding film is formed of aluminum having a silicon content of 0 to 0.5 wt% and the aluminum film forming the wiring film. Silicon content is 0.
It is characterized by being formed of aluminum of 5 to 1.2 wt%.

According to a third aspect of the method of manufacturing a solid-state image pickup device, after forming an aluminum film forming a wiring film of a peripheral circuit, an aluminum film forming a light shielding film is formed. The method for manufacturing a solid-state image pickup device according to claim 4, wherein after forming an aluminum film forming a light-shielding film, an aluminum separation film is formed on at least the surface of the image pickup region, and then an aluminum film forming a wiring film is formed. To do.

[0011]

According to the solid-state image pickup device of the present invention, since the aluminum film forming the light-shielding film is formed of an aluminum material which suppresses the generation of silicon nodules, smear and optical black false signals caused by the silicon nodules of the light-shielding film are produced. And the aluminum film forming the wiring film is made of an aluminum film that suppresses the generation of aluminum spikes, so that it is possible to prevent the generation of aluminum spikes in the wiring film in the peripheral circuits. In addition, it is allowed to make the diffusion layer shallow, so that the parasitic capacitance can be reduced and the peripheral circuit can be highly integrated. Therefore, it is possible to prevent both the generation of silicon nodules and the generation of aluminum spikes.

According to the solid-state imaging device of the second aspect, since the aluminum film forming the light-shielding film has a low silicon content of 0 to 0.5 wt% which is a factor for forming silicon nodules, it is possible to suppress the generation of silicon nodules. Since the aluminum film forming the wiring film contains a large amount of silicon, which is a factor for suppressing aluminum spikes, of 0.5 to 1.2 wt%, aluminum spikes can be suppressed. According to the method of manufacturing a solid-state imaging device of claim 3, since the aluminum film forming the wiring film is formed and then the aluminum film forming the light shielding film is formed, the aluminum film forming the wiring film and the aluminum film forming the light shielding film are formed. Can be formed of another material, and thus the solid-state imaging device according to claim 1 or 2 can be obtained.

According to the method of manufacturing a solid-state image pickup device of the fourth aspect, since the aluminum film forming the light-shielding film is formed and the aluminum film forming the wiring film is formed after that, the aluminum film forming the light-shielding film and the wiring are formed. The aluminum film forming the film can be formed of a material different from that of the aluminum film.
Alternatively, the solid-state image sensor 2 can be obtained. Moreover, since the aluminum separation film is formed after the formation of the aluminum film forming the light-shielding film and before the formation of the aluminum film forming the wiring film, the aluminum film forming the wiring film and the aluminum film forming the light-shielding film therebelow are integrated, It is possible to prevent silicon from moving between both aluminum films and causing silicon nodules.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The solid-state image pickup device of the present invention and its manufacturing method will be described in detail below with reference to the illustrated embodiments. FIG. 1 (A),
(B) is sectional drawing which shows each another Example of the solid-state image sensor of this invention. The respective examples are substantially different from the solid-state imaging device shown in FIG. 5 in that the aluminum film forming the wiring film and the aluminum film forming the light-shielding film are made of different materials and are formed in different steps. Since there are some points, the common points have already been described, so the description thereof will be omitted and only the different points will be described.

In FIGS. 1A and 1B, 9 is an aluminum film which forms a light-shielding film and contains 0 to 0.5 wt% of silicon. That is, the silicon content of the aluminum film forming the light-shielding film is lower than in the conventional case. Reference numeral 10 is an aluminum film forming a wiring film, which is 0.5 to 1.2 wt%
Contains silicon. That is, the silicon content of the aluminum film forming the wiring film is, for example, the same as the conventional one.

In each of the solid-state image pickup elements shown in FIGS. 1A and 1B, the aluminum film 9 forming the light-shielding film is formed of an aluminum film having a low silicon content and thus hardly generating silicon nodules. Since the aluminum film 10 forming the wiring film is formed of an aluminum film having a high silicon content rate and thus less likely to cause aluminum spikes, it is possible to reduce smear due to the silicon nodules of the light-shielding film and optical black false signals.
It is possible to prevent aluminum spikes from being generated in the wiring film in the peripheral circuit, and it is possible to make the diffusion layer shallow, which makes it possible to reduce the parasitic capacitance and increase the degree of integration of the peripheral circuit. Therefore, it is possible to prevent both the generation of silicon nodules and the generation of aluminum spikes.

The solid-state image sensor shown in FIG. 1A and FIG.
The solid-state imaging device shown in (B) is different in the order of forming the aluminum film 9 forming the light-shielding film and the light-shielding film 10 forming the wiring film. 2A and 2B show a method of manufacturing the solid-state imaging device shown in FIG. After forming the contact holes of the transistors in the peripheral circuit, first, as shown in FIG.
As shown in FIG. 1A, an aluminum film 10 forming a wiring film of a peripheral circuit is formed, and then an aluminum film 9 forming a light shielding film is formed as shown in FIG. 2B.
The solid-state imaging device shown in can be obtained.

In this case, after the aluminum film 10 is selectively formed, the aluminum film 9 is formed over the entire surface, and when the selective etching is performed, the aluminum film 10 forming portion forming the wiring film already formed is masked. Since it is necessary, the aluminum film 10 forming the wiring film in the peripheral circuit
It has a structure in which an aluminum film 9 forming a light-shielding film is overlaid on it. However, in this case, since the silicon in the aluminum film 10 functions to suppress the generation of spikes, the generation of spikes can be prevented.

FIGS. 3A to 3C are sectional views showing a method of manufacturing the solid-state image pickup device shown in FIG. 1B in the order of steps.
First, as shown in FIG. 3 (A), an aluminum film 9 forming a light-shielding film is formed, and then, as shown in FIG. 3 (B), a separation film 13 made of, for example, silicon nitride or silicon oxide is formed.

The isolation film 13 is formed by selectively forming the aluminum film 9 forming the light-shielding film, and then forming the aluminum film 1 forming the wiring film.
0 has a two-layer structure in which an aluminum film 9 forming a light-shielding film and an aluminum film 10 having a high silicon content are stacked when 0 is formed by, for example, the aluminum in the aluminum film 10 forming a light-shielding film by forming sintering. It is formed in order to prevent it from moving into the film 9 and causing silicon nodules.

After that, as shown in FIG. 3C, after forming the contact holes, the aluminum film 10 forming the wiring film is formed. Then, the solid-state imaging device shown in FIG. 1B is completed. Note that the silicon-containing aluminum film generally has a silicon content of 1 wt% in many cases, and therefore 1 wt%
% Aluminum film is easy to make. However, the aluminum film forming the light-shielding film has a silicon content of 0 to 0.5 wt%.
I have to That is, the solid solution limit of aluminum must be 0.5 wt% or less. Then, it is difficult to form an aluminum film containing silicon of 0.5 wt% or less.

Therefore, as a method of forming an aluminum film of 0.5 wt% or less, as shown in FIG.
Forming an aluminum film 14 containing 100% silicon,
Aluminum film with silicon content of 0 wt% (pure) 1
5 is laminated on the aluminum film 14 and then subjected to forming annealing, a sufficient annealing time is taken to obtain an arbitrary silicon according to the ratio of the thickness t1 of the aluminum film 14 to the thickness t2 of the aluminum film 15. An aluminum film having a content rate can be obtained. This is because it is possible to move the silicon in the aluminum film 14 to the aluminum film 15 side by forming annealing so that the silicon content can be made uniform over the entire aluminum films 14 and 15. Of course, 0 ≦ t1 ≦ t2 should be satisfied in order to reduce the silicon content to 0.5 wt% or less.

[0023]

According to the solid-state image pickup device of the present invention, the aluminum film forming the light-shielding film is formed of an aluminum material which suppresses the generation of silicon nodules, and the aluminum film forming the wiring film suppresses the generation of aluminum spikes. It is characterized by being formed by.
Therefore, according to the solid-state imaging device of the first aspect, since the aluminum film forming the light-shielding film is formed of the aluminum material that suppresses the generation of silicon nodules, smear and optical black spurious signals generated by the silicon nodules in the light-shielding film are generated. In addition, since the aluminum film forming the wiring film is made of an aluminum film that suppresses the generation of aluminum spikes, it is possible to prevent the generation of aluminum spikes in the wiring film in the peripheral circuit. Allows the diffusion layer to be shallow, which enables reduction of parasitic capacitance and high integration of peripheral circuits. Therefore, it is possible to prevent both the generation of silicon nodules and the generation of aluminum spikes.

According to another aspect of the solid-state imaging device of the present invention, the aluminum film forming the light-shielding film is formed of aluminum having a silicon content of 0 to 0.5 wt%, and the aluminum film forming the wiring film has a silicon content of 0.5 to 0.5%. It is characterized by being formed of 1.2 wt% of aluminum. Therefore,
According to the solid-state imaging device of claim 2, since the aluminum film forming the light-shielding film has a small silicon content of 0 to 0.5 wt% which is a factor for forming silicon nodules, the generation of silicon nodules can be suppressed, and the wiring film can be suppressed. Since the aluminum film forming the above has a large silicon content of 0.5 to 1.2 wt% which is a factor for suppressing the aluminum spike, the aluminum spike can be suppressed.

According to a third aspect of the present invention, there is provided a method of manufacturing a solid-state image pickup device, which comprises forming an aluminum film forming a wiring film of a peripheral circuit and then forming an aluminum film forming a light shielding film. Therefore, according to the method of manufacturing a solid-state imaging device of claim 3, since the aluminum film forming the wiring film is formed and then the aluminum film forming the light shielding film is formed, the aluminum film forming the wiring film and the aluminum forming the light shielding film are formed. The membrane can be made of a different material and, by extension, the membrane of claim 1.
Alternatively, the solid-state image sensor 2 can be obtained.

According to a fourth aspect of the present invention, in the method for manufacturing a solid-state image pickup device, after forming an aluminum film forming a light-shielding film, a silicon movement suppressing film for suppressing silicon movement is formed on at least the surface of the image pickup region, and then a wiring film is formed. It is characterized by forming an aluminum film. Therefore, claim 4
According to the method for manufacturing a solid-state image pickup device, the aluminum film forming the light-shielding film is formed, and the aluminum film forming the wiring film is formed after that, so that the aluminum film forming the light-shielding film and the aluminum film forming the wiring film are formed. Can be formed of another material, and thus the solid-state imaging device according to claim 1 or 2 can be obtained.

Moreover, since the aluminum separation film is formed after the formation of the aluminum film forming the light-shielding film and before the formation of the aluminum film forming the wiring film, the aluminum film forming the wiring film and the aluminum film forming the light-shielding film below the aluminum film are formed. Integrated,
It is possible to prevent silicon from moving between both aluminum films and causing silicon nodules.

[Brief description of drawings]

1A and 1B are cross-sectional views showing another embodiment of the solid-state image pickup device of the present invention.

2A and 2B are cross-sectional views showing a method of manufacturing the solid-state imaging device of FIG. 1A in the order of steps.

3A to 3C are cross-sectional views showing a method of manufacturing the solid-state imaging device of FIG. 1B in the order of steps.

FIG. 4 is a cross-sectional view illustrating an example of a method of forming an aluminum film that forms a light-shielding film.

FIG. 5 is a cross-sectional view showing a schematic configuration of a conventional example of a solid-state image sensor.

6A and 6B are cross-sectional views showing problems to be solved by the invention, FIG. 6A is an explanatory view of smear generation, and FIG. 6B is an explanatory view of optical black false signal. Is.

[Explanation of symbols]

 9 Aluminum film forming a light-shielding film 10 Aluminum film forming a wiring film 13 Aluminum separation film

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[Procedure amendment]

[Submission date] August 17, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title: Solid-state imaging device and method of manufacturing the same

[Claims]

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, particularly a metal film forming a light-shielding film for shielding light except for the light-receiving portion in the image pickup region,
The present invention relates to a solid-state image sensor having a metal film that forms a wiring film of a peripheral circuit, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A solid-state image sensor generally has a structure as shown in FIG. In the drawing, 1 is a semiconductor substrate, which is roughly divided into an imaging region 2 and a peripheral circuit 3.
The imaging region 2 is composed of an effective pixel portion 4 in which effective pixels are present, and an optical black portion 5 in which pixels are shielded from the surface and light does not enter.

Reference numeral 6 is a light receiving element for photoelectric conversion, which constitutes a pixel. Reference numeral 7 denotes a diffusion layer which forms, for example, a source and a drain of a transistor of the peripheral circuit, and 8a denotes a vertical transfer electrode, which is made of polycrystalline silicon. 8b is a silicon gate electrode of the above transistor. The interlayer film and the passivation film are not shown for convenience. 9 is a light-shielding film made of aluminum,
The image pickup area is covered except for the portion where the effective pixels are formed. In the effective pixel portion 4, the light is prevented from entering the transfer register to eliminate smear, and in the optical black portion 5, the light receiving element itself forming the pixel is provided. It blocks the entry of light into the optical black level signal.

Reference numeral 10 is an aluminum wiring film, which is in contact with the diffusion layer 7 which forms the source and drain of the transistor of the peripheral circuit. In the past, the aluminum film 10 forming the wiring film and the aluminum film 9 forming the light-shielding film were simultaneously formed of the same material. The material was specifically aluminum containing 1 wt% of silicon. The reason why the aluminum film containing 1 wt% of silicon is formed in this manner is to prevent a spike of aluminum toward the diffusion layer 7 side due to melting of silicon in the contact portion of the aluminum film 10 forming the wiring film. . Reference numeral 11 indicates a transfer register.

[0005]

By the way, in the conventional solid-state image pickup device, the light-shielding property of the light-shielding film 9 made of aluminum is deteriorated, smear occurs in the effective pixel portion 4, and optical black in the optical black portion 5. There was a problem that a false signal was generated. This is because when 1 wt% of silicon is contained in the aluminum film, silicon in aluminum is deposited, silicon nodules are generated, and light is transmitted therethrough due to the low light-shielding property of silicon nodules. To do.

That is, after forming an aluminum film forming a light-shielding film and a wiring film, a forming annealing (temperature 30
However, if silicon is present in the aluminum film, the silicon nodules 12 may be formed by the growth of the silicon during the annealing. The silicon nodule 12 has a poor light shielding property. Therefore, FIG.
As shown in FIG. 7A, the silicon nodules 12 above the vertical transfer electrodes 8 in the effective pixel portion cause smears, and as shown in FIG. 7B, the silicon nodules 12 on the light receiving element 6 of the optical black 5 are formed. Causes an optical black false signal and is not preferable.

By the way, as a light-shielding film, a so-called two-layer structure aluminum in which pure aluminum and aluminum containing 1% of silicon are continuously formed is formed, and pure aluminum and aluminum containing 1% of silicon are formed. When the smear when the film thickness ratio was changed was examined, a film thickness ratio / smear relationship diagram as shown in FIG. 8 was obtained. From FIG. 8, the smear increases as the film thickness ratio of the aluminum containing silicon increases, and the ratio of the film thickness of the silicon containing aluminum to the total film thickness becomes 2
It can be seen that the smear increases twice as much as it is increased from 5% to 100%, and it can be said that the selection of the light-shielding film material is highly important.

Therefore, it has been attempted to reduce the silicon content rate of the aluminum film to less than 1 wt%. However, if this is done, a spike will occur in the aluminum film forming the wiring film of the peripheral circuit, so that a spike will occur. However, it is necessary to increase the depth of the diffusion layer 7 so as not to cause any trouble, which not only hinders miniaturization and high integration, but also increases the parasitic capacitance of the transistor.
Therefore, it is not a good idea to reduce the silicon content. As described above, conventionally, there is a trade-off relationship between preventing the generation of silicon nodules and preventing the generation of aluminum spikes.

The present invention has been made to solve such a problem, and has a metal film which forms a light-shielding film for shielding the light except for the light-receiving portion in the image pickup region and a metal film which forms a wiring film of peripheral circuits. In the solid-state image sensor, the metal film that forms the light-shielding film prevents the generation of smear and silicon black nodules that cause optical black spurious signals, and the metal film that forms the wiring film of the peripheral circuit prevents the deterioration of transistor characteristics. The purpose is to prevent spikes from occurring.

[0010]

According to another aspect of the solid-state image pickup device of the present invention, the metal film forming the light-shielding film is formed of a metal material which suppresses the generation of silicon nodules, and the metal film forming the wiring film prevents the generation of metal spikes. It is characterized in that it is formed of a suppressing metal material. The solid-state imaging device according to claim 2 is the solid-state imaging device according to claim 1, wherein the metal film forming the light-shielding film is formed of aluminum having a silicon content of 0 to 0.5 wt% and the metal film forming the wiring film contains silicon. The amount is 0.5-1.2w
It is characterized by being formed of t% aluminum.

According to a third aspect of the present invention, there is provided a method of manufacturing a solid-state image pickup device, which comprises forming a metal film forming a wiring film of a peripheral circuit and then forming a metal film forming a light shielding film. The solid-state imaging device manufacturing method according to claim 4, wherein after forming the metal film forming the light-shielding film, the metal separation film is formed at least on the surface of the imaging region, and then the metal film forming the wiring film is formed. To do.

[0012]

According to the solid-state image pickup device of the present invention, since the metal film forming the light-shielding film is made of a metal material that suppresses the generation of silicon nodules, smear and optical black false signals generated by the silicon nodules in the light-shielding film are generated. The metal film forming the wiring film is made of a metal film that suppresses the generation of metal spikes, so that it is possible to prevent metal spikes from being generated in the wiring film in the peripheral circuit. In addition, it is allowed to make the diffusion layer shallow, so that the parasitic capacitance can be reduced and the peripheral circuit can be highly integrated. Therefore, it is possible to both prevent the generation of silicon nodules and the generation of metal spikes.

According to the solid-state image pickup device of the second aspect, the aluminum film which is the metal film forming the light-shielding film has a silicon content of 0 to 0.5 wt% which is a factor for forming silicon nodules.
Therefore, the generation of silicon nodules can be suppressed, and the aluminum film, which is a metal film forming the wiring film, has a silicon content of 0.5 to 5 which is a factor for suppressing metal spikes.
Since it is as large as 1.2 wt%, metal spikes can be effectively suppressed. According to the method for manufacturing a solid-state imaging device of claim 3, since the metal film forming the wiring film is formed and then the metal film forming the light shielding film is formed, the metal film forming the wiring film and the aluminum film forming the light shielding film are formed. Can be formed of another material, and thus the solid-state imaging device according to claim 1 or 2 can be obtained.

According to the method of manufacturing a solid-state imaging device of claim 4, since the metal film forming the light-shielding film is formed and the metal film forming the wiring film is formed after that, the metal film forming the light-shielding film and the wiring are formed. The metal film forming the film can be formed of a different material, and by extension, the solid-state imaging device according to claim 1 or 2 can be obtained. In addition, since the metal separation film is formed after the formation of the metal film forming the light-shielding film and before the formation of the metal film forming the wiring film, the metal film forming the wiring film and the metal film forming the light-shielding film thereunder are integrated. It is possible to prevent silicon from moving between the metal films and causing silicon nodules.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The solid-state image pickup device of the present invention and its manufacturing method will be described in detail below with reference to the illustrated embodiments. FIG. 1 (A),
(B) is sectional drawing which shows each another Example of the solid-state image sensor of this invention. The respective examples are substantially different from the solid-state imaging device shown in FIG. 5 in that the aluminum film forming the wiring film and the aluminum film forming the light-shielding film are made of different materials and are formed in different steps. Since there are some points, the common points have already been described, so the description thereof will be omitted and only the different points will be described.

In FIGS. 1A and 1B, 9 is an aluminum film forming a light-shielding film, which contains 0 to 0.5 wt% of silicon. That is, the silicon content of the aluminum film forming the light-shielding film is lower than in the conventional case. Reference numeral 10 is an aluminum film forming a wiring film, which is 0.5 to 1.2 wt%
Contains silicon. That is, the silicon content of the aluminum film forming the wiring film is, for example, the same as the conventional one.

In each of the solid-state image pickup devices shown in FIGS. 1A and 1B, the aluminum film 9 forming the light-shielding film is formed of an aluminum film having a low silicon content rate and thus hardly causing silicon nodules. Since the aluminum film 10 forming the wiring film is formed of an aluminum film having a high silicon content rate and thus less likely to cause aluminum spikes, it is possible to reduce smear due to the silicon nodules of the light-shielding film and optical black false signals.
It is possible to prevent aluminum spikes from being generated in the wiring film in the peripheral circuit, and it is possible to make the diffusion layer shallow, which makes it possible to reduce the parasitic capacitance and increase the degree of integration of the peripheral circuit. Therefore, it is possible to prevent both the generation of silicon nodules and the generation of aluminum spikes.

The solid-state image sensor shown in FIG. 1A and FIG.
The solid-state imaging device shown in (B) is different in the order of forming the aluminum film 9 forming the light-shielding film and the light-shielding film 10 forming the wiring film. 2A and 2B show a method of manufacturing the solid-state imaging device shown in FIG. After forming the contact holes of the transistors in the peripheral circuit, first, as shown in FIG.
As shown in FIG. 1A, an aluminum film 10 forming a wiring film of a peripheral circuit is formed, and then an aluminum film 9 forming a light shielding film is formed as shown in FIG. 2B.
The solid-state imaging device shown in can be obtained.

In this case, after the aluminum film 10 is selectively formed, the aluminum film 9 is formed over the entire surface, and when the selective etching is performed, a portion of the aluminum film 10 forming the wiring film which has already been formed is masked. Since it is necessary, the aluminum film 10 forming the wiring film in the peripheral circuit
It has a structure in which an aluminum film 9 forming a light-shielding film is overlaid on it. However, in this case, since the silicon in the aluminum film 10 functions to suppress the generation of spikes, the generation of spikes can be prevented.

3A to 3C are sectional views showing a method of manufacturing the solid-state image pickup device shown in FIG. 1B in the order of steps.
First, as shown in FIG. 3 (A), an aluminum film 9 forming a light-shielding film is formed, and then, as shown in FIG. 3 (B), a separation film 13 made of, for example, silicon nitride or silicon oxide is formed.

The isolation film 13 is formed by selectively forming the aluminum film 9 forming the light-shielding film, and then forming the aluminum film 1 forming the wiring film.
0 has a two-layer structure in which an aluminum film 9 forming a light-shielding film and an aluminum film 10 having a high silicon content are stacked when 0 is formed by, for example, the aluminum in the aluminum film 10 forming a light-shielding film by forming sintering. It is formed in order to prevent it from moving into the film 9 and becoming a factor for generating silicon nodules, or to serve as an etching stopper when the aluminum film 10 laminated on the imaging region 2 is etched. .

After that, as shown in FIG. 3C, after forming the contact holes, the aluminum film 10 forming the wiring film is formed. Then, the solid-state imaging device shown in FIG. 1B is completed. Note that the silicon-containing aluminum film generally has a silicon content of 1 wt% in many cases, and therefore 1 wt%
% Aluminum film is easy to make. However, the aluminum film forming the light-shielding film has a silicon content of 0 to 0.5 wt%.
I have to That is, the solid solution limit of aluminum must be 0.5 wt% or less. Then, it is difficult to form an aluminum film containing silicon of 0.5 wt% or less.

Therefore, as a method for forming an aluminum film of 0.5 wt% or less, as shown in FIG.
Forming an aluminum film 14 containing 100% silicon,
Aluminum film with silicon content of 0 wt% (pure) 1
5 is laminated on the aluminum film 14 and then subjected to forming annealing, a sufficient annealing time is taken to obtain an arbitrary silicon according to the ratio of the thickness t1 of the aluminum film 14 to the thickness t2 of the aluminum film 15. An aluminum film having a content rate can be obtained. This is because it is possible to move the silicon in the aluminum film 14 to the aluminum film 15 side by forming annealing so that the silicon content can be made uniform over the entire aluminum films 14 and 15. Of course, 0 ≦ t1 ≦ t2 should be satisfied in order to reduce the silicon content to 0.5 wt% or less.

FIGS. 5A to 5D are sectional views showing still another example of the method of manufacturing the solid-state image pickup device of the present invention in the order of steps. (A) A diffusion layer (not shown) is formed in a predetermined portion of the semiconductor substrate 1 by a conventional manufacturing method, and a transfer electrode 15 made of polysilicon is formed on the gate insulating film 14 (note that 16 is an interlayer insulating film). Film), a reflow film 17 made of PSG, for example, is formed, and after a necessary heat treatment, a light shielding film made of aluminum (thickness: 1.0 μm, for example) of the first layer.
m) is formed. Pure aluminum having a high light shielding property is used as an aluminum material forming the light shielding film 9.

Needless to say, the patterning of the light-shielding film 9 is performed by applying a photoresist film, exposing, developing and etching. Although pure aluminum has a weak effect of suppressing aluminum spikes, the light-shielding film 9 does not have any portion in contact with the silicon semiconductor substrate 1, so there is no possibility of aluminum spike problems. FIG. 5A shows a state after the patterning of the light shielding film 9 is completed.

(B) Next, as shown in FIG. 5B, a separation film 13 for separating the first-layer aluminum 9 and the second-layer aluminum 10 to be formed thereafter is formed. For example, it is formed of 100 mm PSG having a thickness of about 2 wt%. (C) Next, a contact hole 18 for contacting the aluminum wiring film and the semiconductor substrate 1 is formed, then an aluminum film forming a wiring film is formed, and then the aluminum film is patterned by the same method as the patterning of the light shielding film 9. Is patterned to form the wiring film 10. This wiring film 10 is, for example, 1
% Aluminum, which has a thickness of, for example, 1 μm to suppress silicon nodules containing silicon. FIG. 5C shows a state after the wiring film 10 is formed.

(D) Then, as shown in FIG.
The overcoat film 19 is formed. Further, a pad film (not shown) is formed. The metal film 9 forming the light-shielding film and the metal film 10 forming the wiring film can be formed of different materials by the manufacturing method of such a solid-state image sensor, and after the metal film 9 forming the light-shielding film is formed. , A metal film 10 forming a wiring film
Since the metal separation film 13 is formed before the formation, the metal film 10 that forms the wiring film and the metal film 9 that forms the light-shielding film therebelow are integrated, and silicon moves between the both metal films to cause the generation of silicon nodules. Can be prevented.

In each of the above embodiments, pure aluminum and silicon-containing aluminum were used as the material of the metal film forming the light-shielding film and the wiring film, but the present invention is not necessarily limited thereto. in short,
It is preferable to use a metal material having excellent light-shielding properties as the light-shielding film and a metal material that does not generate metal spikes as the wiring film. For example, refractory metals such as tungsten and molybdenum and their silicides and metals such as copper are converted to aluminum. It can be considered to be used as an alternative material.

[0029]

According to the solid-state image pickup device of the present invention, the metal film forming the light-shielding film is formed of a metal material which suppresses the generation of silicon nodules, and the metal film forming the wiring film suppresses the generation of metal spikes. It is characterized by being formed by. Therefore, according to the solid-state imaging device of claim 1,
Since the metal film forming the light-shielding film is formed of a metal material that suppresses the generation of silicon nodules, it is possible to reduce smear and optical black false signals caused by the silicon nodules of the light-shielding film, and also to form the wiring film. Since the metal film is made of a metal film that suppresses the generation of metal spikes, it is possible to prevent the metal spikes from being generated in the wiring film in the peripheral circuit, which in turn allows the diffusion layer to be shallow, thus reducing parasitic capacitance. And the peripheral circuits can be highly integrated. Therefore, it is possible to both prevent the generation of silicon nodules and the generation of metal spikes.

According to another aspect of the solid-state imaging device of the present invention, the metal film forming the light-shielding film is formed of aluminum having a silicon content of 0 to 0.5 wt%, and the metal film forming the wiring film has a silicon content of 0.5 to 0.5 wt%. It is characterized by being formed of 1.2 wt% of aluminum. Therefore, according to the solid-state imaging device of claim 2, since the aluminum film, which is the metal film forming the light-shielding film, has a low silicon content of 0 to 0.5 wt% which causes formation of silicon nodules, the generation of silicon nodules is suppressed. In addition, the aluminum film, which is a metal film forming the wiring film, has a large content of silicon, which is a factor for suppressing the metal spike, of 0.5 to 1.2 wt%, so that the metal spike can be suppressed.

The method of manufacturing a solid-state image pickup device according to a third aspect is characterized in that after forming a metal film forming a wiring film of a peripheral circuit, a metal film forming a light shielding film is formed. Therefore, according to the method for manufacturing a solid-state imaging device of claim 3, since the metal film forming the wiring film is formed and then the metal film forming the light shielding film is formed, the metal film forming the wiring film and the metal forming the light shielding film are formed. The film and the film can be formed of a different material, and thus the solid-state imaging device according to claim 1 or 2 can be obtained.

According to a fourth aspect of the present invention, in the method for manufacturing a solid-state image pickup device, after forming a metal film that forms a light-shielding film, a metal separation film that suppresses silicon migration is formed at least on the surface of the image pickup region, and then a metal that forms a wiring film. It is characterized by forming a film. Therefore, according to the method for manufacturing a solid-state imaging device of claim 4, since the metal film forming the light-shielding film is formed and the metal film forming the wiring film is formed after that, the metal film forming the light-shielding film and the wiring film are formed. It is possible to form the solid-state imaging device according to claim 1 or 2 by forming it with a material different from that of the metal film.

Moreover, since the metal separation film is formed after the formation of the metal film forming the light shielding film and before the formation of the metal film forming the wiring film,
It is possible to prevent the metal film that forms the wiring film and the metal film that forms the light-shielding film therebelow from being integrated, and prevent silicon from moving between the metal films to cause silicon nodules.

[Brief description of drawings]

1A and 1B are cross-sectional views showing another embodiment of the solid-state image pickup device of the present invention.

2A and 2B are cross-sectional views showing a method of manufacturing the solid-state imaging device of FIG. 1A in the order of steps.

3A to 3C are cross-sectional views showing a method of manufacturing the solid-state imaging device of FIG. 1B in the order of steps.

FIG. 4 is a cross-sectional view illustrating an example of a method for forming a metal film that forms a light-shielding film.

5A to 5D are cross-sectional views showing still another example of a method of manufacturing a solid-state image sensor in the order of steps.

FIG. 6 is a cross-sectional view showing a schematic configuration of a conventional example of a solid-state image sensor.

7A and 7B are cross-sectional views showing problems to be solved by the invention, FIG. 7A is an explanatory diagram of occurrence of smear, and FIG. 7B is an explanatory diagram of optical black false signal. Is.

FIG. 8 is an Al film thickness ratio / smear relationship diagram showing a relationship between a ratio of a film thickness of an aluminum film containing silicon to a film thickness of an aluminum film having a two-layer structure of an aluminum film containing silicon and an aluminum film not containing silicon and a smear. Is.

[Explanation of reference numerals] 9 metal film forming a light-shielding film 10 metal film forming a wiring film 13 metal separation film

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[Document name to be corrected] Drawing

[Correction target item name] All drawings

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Claims (4)

[Claims] 1. In a solid-state image sensor having an aluminum film forming a light-shielding film for shielding light except for a light-receiving part of an image pickup region and an aluminum film forming a wiring film of a peripheral circuit, the aluminum film forming the light-shielding film generates silicon nodules. Solid-state imaging device, characterized in that it is formed of an aluminum material that suppresses the occurrence of aluminum spikes 2. An aluminum film forming a light-shielding film is formed of aluminum having a silicon content of 0 to 0.5 wt%, and an aluminum film forming a wiring film has a silicon content of 0.5 to 1.2 wt%. The solid-state imaging device according to claim 1, wherein the solid-state imaging device is formed of aluminum. 3. The method for manufacturing a solid-state image pickup device according to claim 1, wherein the aluminum film forming the light-shielding film is formed after forming the aluminum film forming the wiring film of the peripheral circuit. 4. The solid-state imaging device according to claim 1, wherein the aluminum film forming the light-shielding film is formed, the aluminum separation film is formed, and then the aluminum film forming the wiring film is formed. Production method