WO2016103936A1

WO2016103936A1 - Solid-state imaging element and method for manufacturing solid-state imaging element

Info

Publication number: WO2016103936A1
Application number: PCT/JP2015/081624
Authority: WO
Inventors: 裕行川野; 康彦末吉
Original assignee: シャープ株式会社
Priority date: 2014-12-24
Filing date: 2015-11-10
Publication date: 2016-06-30
Also published as: JPWO2016103936A1; JP6301500B2

Abstract

To avoid decrease in the light blocking properties of a light blocking part that blocks light to an optical black region, while suppressing the thickness of the light blocking part. A light blocking part (170), which is formed on a semiconductor substrate (120) and blocks light to an optical black region (B), is provided with an upper Al light blocking film (12) that has a film thickness from 50 nm to 125 nm (inclusive).

Description

Solid-state imaging device and method for manufacturing solid-state imaging device

The present invention relates to a solid-state imaging device and a method for manufacturing the solid-state imaging device, and more particularly to a solid-state imaging device including a light-shielding unit that shields an optical black region and a method for manufacturing the solid-state imaging device.

2. Description of the Related Art Conventionally, research is being conducted to ensure the light shielding property of a light shielding portion that shields an optical black region (hereinafter referred to as an OB region) of a solid-state imaging device.

For example, in Patent Document 1 listed below, in order to solve the problem of a single-layer aluminum light-shielding portion (hereinafter, aluminum is abbreviated as “Al”) “local light transmission occurs due to metal voids” A light shielding part having a three-layer structure including an Al light shielding film, an intervening film, and an upper Al light shielding film is disclosed. With reference to FIG. 14, the light-shielding part according to Patent Document 1 will be described.

FIG. 14 is a cross-sectional view of the solid-state imaging device 1000 including the light shielding unit 20 according to Patent Document 1. As shown in FIG. 14, the solid-state imaging device 1000 disclosed in Patent Document 1 includes a light receiving unit 101 formed in a semiconductor substrate 120 and

interlayer insulating films

106, 109, 112, formed on the semiconductor substrate 120. 114 and a conventional light shielding part 20 formed on the interlayer insulating film 114. The conventional light shielding portion 20 includes a conventional lower light shielding film 20d, a conventional intervening film 20m, and a conventional upper light shielding film 20u in order from the side closer to the semiconductor substrate 120. That is, the conventional light shielding unit 20 includes a conventional lower Al light shielding film 20d, a conventional upper Al light shielding film 20u formed in a layer above the conventional lower Al light shielding film 20d, and a conventional lower layer. It includes a three-layer structure including a conventional intervening film 20m formed in a region sandwiched between the Al light shielding film 20d and the conventional upper Al light shielding film 20u. The conventional intervening film 20m is formed of a refractory metal having a particle diameter smaller than that of Al and its nitride film, silicide film, or oxide film. Therefore, in the conventional light shielding part 20, the metal voids in the conventional lower Al light shielding film 20d and the metal voids in the conventional upper Al light shielding film 20u are discontinuous, and the conventional light shielding part 20 passes through the metal voids. This prevents a decrease in light shielding performance due to light leaking.

Japanese Patent Publication “JP-A-6-151794 (published May 31, 1994)”

As shown in FIG. 14, in the conventional light shielding unit 20 according to Patent Document 1, the film thickness of the conventional upper Al light shielding film 20u is the film of the conventional intervening film 20m in order to ensure the light shielding property. It is thicker than the thickness. For a light shielding part that shields the OB region of the solid-state imaging device, as a method for securing and improving the light shielding property of the light shielding part, a method of increasing the thickness of the light shielding film included in the light shielding part is generally used. It is.

On the other hand, the inventors of the present invention have found that the conventional upper-layer Al light-shielding film 20u is thick in the conventional light-shielding portion 20, and therefore metal voids are likely to occur. Although the mechanism of occurrence of metal voids is not clear, there are holes in the conventional upper Al light shielding film 20u, and the voids are caused by external factors (for example, film stress of the conventional light shielding part 20, And the heat treatment temperature, etc.), it is considered that the metal agglomerates and becomes metal voids or metal bubbles.

That is, it is considered that the conventional upper Al light shielding film 20u has a large film thickness and many vacancies, and therefore metal voids are likely to occur.

Further, the conventional light-shielding portion 20 is prone to metal bubbles (aggregation of metal voids) due to stress generated from the difference in thermal expansion coefficient between the conventional upper Al light-shielding film 20u and the conventional intervening film 20m. it is conceivable that.

When metal bubbles (aggregation of metal voids) are generated, light leaks through the metal bubbles, resulting in a reduction in light shielding performance.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the light shielding property of the light shielding part while suppressing the thickness of the light shielding part that shields the OB region. An object of the present invention is to provide an imaging device and a method for manufacturing a solid-state imaging device.

In order to solve the above-described problem, a solid-state imaging device according to an aspect of the present invention is a solid-state imaging device including a light-shielding unit that shields an optical black region formed on a substrate. In order from the side closer to the substrate, a lower-layer light-shielding film, an intervening film, and an upper-layer light-shielding film are included, and the lower-layer light-shielding film and the upper-layer light-shielding film are formed of aluminum or an aluminum alloy containing aluminum as a main component. The film thickness is 50 nm or more and 125 nm or less.

In order to solve the above problems, a method for manufacturing a solid-state imaging device according to an aspect of the present invention is a method for manufacturing a solid-state imaging device including a light-shielding portion that shields an optical black region formed on a substrate. The light shielding portion includes a lower light shielding film, an intervening film, and an upper light shielding film in order from the side closer to the substrate, and a lower light shielding film forming step of forming the lower light shielding film with aluminum or an aluminum alloy containing aluminum as a main component. And an upper light-shielding film forming step of forming the upper light-shielding film which is aluminum or an aluminum alloy containing aluminum as a main component and has a film thickness of 50 nm or more and 125 nm or less.

According to one aspect of the present invention, there is an effect that it is possible to avoid a reduction in the light shielding property of the light shielding part while suppressing the thickness of the light shielding part that shields the OB region.

It is sectional drawing of the solid-state image sensor which concerns on Embodiment 1 of this invention. It is a top view which shows schematic structure of the solid-state image sensor which concerns on each embodiment of this invention. 2 is a cross-sectional view for explaining the film thicknesses of a lower layer light shielding film, an intervening film, and an upper layer light shielding film included in the light shielding part of the light shielding part of the solid-state imaging device of FIG. It is sectional drawing explaining the manufacturing method of the solid-state image sensor of FIG. It is sectional drawing explaining the manufacturing method of the solid-state image sensor of FIG. 1, and is sectional drawing explaining the manufacturing process following the manufacturing process shown in FIG. It is sectional drawing explaining the manufacturing method of the solid-state image sensor of FIG. 1, and is sectional drawing explaining the manufacturing process following the manufacturing process shown in FIG. It is a flowchart explaining the outline | summary of the manufacturing method of the solid-state image sensor of FIG. It is sectional drawing of the solid-state image sensor which concerns on Embodiment 2 of this invention. It is sectional drawing of the solid-state image sensor which concerns on Embodiment 3 of this invention. It is sectional drawing explaining the manufacturing method of the solid-state image sensor which concerns on Embodiment 4 of this invention. It is a figure explaining the relationship between the film thickness of the upper-layer light shielding Al film of the solid-state image sensor which concerns on each embodiment of this invention, and a metal bubble generation frequency. It is a figure explaining the relationship between intervening film stress and metal bubble generation frequency. It is a figure explaining the relationship between hydrogen sintering process temperature and metal bubble generation frequency. It is sectional drawing of the solid-state image sensor concerning patent document 1. FIG.

[Embodiment 1]
Hereinafter, a solid-state imaging device 100 according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 7. The solid-state image sensor 100 is, for example, a CMOS image sensor. First, the outline of the solid-state imaging device 100 will be described as follows.

That is, the solid-state imaging device 100 is a solid-state imaging device including a light-shielding unit 170 that shields the optical black region B formed on the semiconductor substrate 120 (substrate), and the light-shielding unit 170 is from the side close to the semiconductor substrate 120. In order, it includes a third layer aluminum wiring 10 (lower light shielding film), an intervening film 11, and an upper layer aluminum light shielding film 12 (upper layer light shielding film), and the third layer aluminum wiring 10 and upper layer aluminum light shielding film 12 are made of aluminum or aluminum. The upper aluminum light-shielding film 12 has a thickness of 50 nm or more and 125 nm or less.

Here, it is considered that one cause of the metal void generated in the upper layer aluminum (hereinafter abbreviated as “Al”) light shielding film 12 is a hole existing in the upper layer Al light shielding film 12. The solid-state imaging device 100 reduces the film thickness of the upper Al light shielding film 12, specifically, by setting the film thickness of the upper aluminum light shielding film 12 to 50 nm or more and 125 nm or less. 12 is reduced. Therefore, the solid-state imaging device 100 can prevent the occurrence of metal voids in the upper Al light-shielding film 12 and avoid the deterioration of the light-shielding property. Further, in the solid-state imaging device 100, the thickness of the upper light shielding part 12 can be suppressed by reducing the film thickness of the upper Al light shielding film 12 to 50 nm or more and 125 nm or less. That is, the solid-state imaging device 100 can avoid a reduction in the light shielding property of the light shielding unit 170 while suppressing the thickness of the light shielding unit 170 that shields the optical black region (hereinafter abbreviated as “OB region”).

Furthermore, the tensile stress of the intervening film 11 of the solid-state imaging device 100 is 5.0E8 Pa or more and 7.0E8 Pa or less. Although details will be described later with reference to FIG. 12, the solid-state imaging device 100 is controlled so that the difference in thermal expansion coefficient between the intervening film 11 and the upper aluminum light shielding film 12 is reduced. Therefore, the solid-state imaging device 100 can suppress the generation of metal bubbles due to the stress caused by the film stress.

The outline of the solid-state imaging device 100 can be paraphrased as follows. That is, the solid-state imaging device 100 includes a third-layer Al wiring 10, an upper-layer Al light shielding film 12 formed in a layer above the third-layer Al wiring 10, and a third-layer Al wiring 10 in the OB region. And an intervening film 11 formed in a region sandwiched between the upper Al light shielding film 12 and a light shielding portion 170 having a multilayer structure. The third layer Al wiring 10 in the OB region also serves as a lower Al light shielding film.

According to the above configuration, the solid-state imaging device 100 can reduce the voids in the upper Al light shielding film 12 that are a cause of metal voids, and suppress the generation of metal voids, thereby reducing the light shielding performance. It can be avoided. In addition, the solid-state imaging device 100 can suppress the thickness of the entire light shielding unit 170. Therefore, the solid-state imaging device 100 can avoid a decrease in the light shielding property of the light shielding unit 170 while suppressing the thickness of the light shielding unit 170 that shields the optical black region (hereinafter abbreviated as “OB region”).

Next, the solid-state imaging device 100 having been outlined above, in particular, the light-shielding portion 170 of the solid-state imaging device 100 will be described in detail with reference to FIG.

(Details of solid-state image sensor)
FIG. 1 is a cross-sectional view of a solid-state imaging device 100 according to Embodiment 1 of the present invention. The solid-state imaging device 100 has the same configuration as that of a general CMOS type image sensor except for the configuration related to the light shielding unit 170, and the details will be omitted. However, the outline will be described as follows. .

That is, as shown in FIG. 1, the solid-state imaging device 100 includes a light receiving unit 101, a floating diffusion unit 102, and an element separation unit 103. The light receiving unit 101 includes, for example, a photodiode (photoelectric conversion element), is arranged in a matrix form in the semiconductor substrate 120, and generates a signal charge by photoelectric conversion of image light (incident light) from a subject. The floating diffusion unit 102 (hereinafter abbreviated as “FD unit 102”) is provided for each pixel of the plurality of light receiving units 101, and converts signal charges obtained by photoelectric conversion into voltage signals. The element separating unit 103 is for electrically separating the light receiving unit 101 and the FD unit 102.

The solid-state imaging device 100 also includes a gate insulating film 104, a charge transfer electrode 105 made of a polysilicon electrode, an interlayer insulating film 106, a through hole 107, a first layer Al wiring 108, an interlayer insulating film 109, a through hole 110, a first hole. A second layer Al wiring 111, an interlayer insulating film 112, and a through hole 113 are included.

The solid-state imaging device 100 further includes a light shielding unit 170 that shields the optical black region B formed on the semiconductor substrate 120 (substrate). As shown in FIG. 1, the light shielding portion 170 includes a third-layer Al wiring 10, which is a lower AL light shielding film, an intervening film 11, and an upper aluminum light shielding film 12 in order from the side closer to the semiconductor substrate 120. The third-layer Al wiring 10 and the upper-layer aluminum light shielding film 12 are made of aluminum or an aluminum alloy containing aluminum as a main component.

The third-layer Al wiring 10 is an Al wiring as a lower-layer Al light-shielding film provided on the side closest to the semiconductor substrate 120 in the light-shielding portion 170, and the film thickness of the third-layer Al wiring 10 is 150 nm or more, 250 nm or less. Further, the solid-state imaging device 100 uses titanium nitride (TiN) as the interposition film 11, and the interposition film 11 has a thickness of 100 nm. The film thickness of the upper Al light shielding film 12 is preferably 50 nm or more and 125 nm or less, and more preferably 50 nm or more and 90 nm or less. In the solid-state imaging device 100, the upper Al light shielding film 12 has a thickness of 70 nm and is thinner than the intervening film 11 having a thickness of 100 nm.

However, as will be described later, the film thickness of the upper Al light shielding film 12 may be 50 nm or more and 125 nm or less, and the film thickness of the upper Al light shielding film 12 is larger than the intervening film 11 having a film thickness of 100 nm. Thinness is not essential. For example, the thickness of the upper Al light shielding film 12 may be 125 nm, and the thickness of the intervening film 11 may be 100 nm.

When the film thickness of the upper Al light shielding film 12 is 125 nm or less, it is possible to reduce the occurrence probability of vacancies existing in the upper Al light shielding film 12 and suppress the generation of metal bubbles. However, when the film thickness of the upper Al light shielding film 12 is smaller than 50 nm, the transmittance of incident light is increased and the light shielding property is deteriorated.

Next, a schematic configuration of the solid-state imaging device 100 described so far with reference to FIG. 1 will be described with reference to FIG.

FIG. 2 is a plan view showing a schematic configuration of the solid-state imaging device according to each embodiment of the present invention. As shown in FIG. 2, the solid-state imaging device 100 includes a rectangular effective pixel area A formed in the center, an OB area B arranged around the effective pixel area A, and an OB area B. And a peripheral circuit region C arranged around the periphery.

In the effective pixel area A and the OB area B, the light receiving portions 101 are arranged in a matrix, and the effective pixel area A and the OB area B constitute a pixel area. The effective pixel region A is a region where the light receiving unit 101 that is actually used for imaging is arranged in the light receiving units 101 arranged in a matrix, and generates signal charges by photoelectrically converting incident light from a subject. . The OB region B is a region in which the light receiving units 101 used for black detection are arranged among the light receiving units 101 arranged in a matrix. The peripheral circuit area C is an area in which drivers (peripheral circuits) for controlling signal transfer and signal reading are arranged.

FIG. 3 shows an embodiment in which the film thickness of the upper AL light shielding film 12 is thinner than the film thickness of the intervening film 11, and the third layer AL included in the light shielding part 170 for the light shielding part 170 of the solid-state imaging device 100. 4 is a cross-sectional view for explaining the film thicknesses of a wiring 10, an intervening film 11, and an upper aluminum light shielding film 12. FIG. As shown in FIG. 3, in the light shielding portion 170 of the solid-state imaging device 100, the film thickness of the upper AL light shielding film 12 is thinner than the film thickness of the intervening film 11.

As shown in FIG. 3, the solid-state imaging device 100 includes a light shielding unit 170 having a multilayer structure using an AL wiring layer used for a peripheral circuit. The film thickness of the upper AL light shielding film 12 of the light shielding portion 170 is smaller than the film thickness of the intervening film 11. Here, it is considered that one cause of the metal void generated in the upper Al light shielding film 12 is a vacancy existing in the upper Al light shielding film 12. In the solid-state imaging device 100, the thickness of the upper Al light-shielding film 12 is 50 nm or more and 90 nm or less, which is smaller than the thickness of the intervening film 11, so that the holes present in the upper Al light-shielding film 12 are further reduced. It is decreasing. Therefore, the solid-state imaging device 100 can avoid a decrease in light shielding property due to metal bubbles. Further, in the solid-state imaging device 100, the thickness of the entire light shielding portion 170 can be further suppressed by making the film thickness of the upper Al light shielding film 12 50 nm or more and 90 nm or less, which is smaller than the film thickness of the intervening film 11. In addition, an increase in the distance between the semiconductor substrate 120 and the lens 17 can be minimized. Therefore, since the solid-state imaging device 100 has a short distance until the incident light shown in FIG. 1 reaches the light receiving unit 101, attenuation of the incident light can be reduced and deterioration of sensitivity can be prevented. In addition, although the light shielding part of the CMOS type image sensor has been described so far, the light shielding part of the CCD type image sensor can be configured similarly.

Next, in order to facilitate understanding of the present invention, the knowledge obtained by the inventor of the present invention regarding the frequency of occurrence of metal bubbles will be described with reference to FIGS.

(Organization of matters discovered by the inventors of the present invention up to the present invention)
The inventor of the present invention experimented how the metal bubble occurrence frequency, the film thickness of the upper light-shielding Al film, the film stress of the intervening film, and the hydrogen sintering temperature were related, and obtained the following knowledge . That is, the inventors of the present invention have found that the generation of metal bubbles can be suppressed by setting the film thickness of the upper light-shielding film to 50 nm or more and 125 nm or less. The inventors of the present invention have also found that the generation of metal bubbles can be suppressed by setting the tensile stress of the intervening film to 5.0E8 Pa or more and 7.0E8 Pa or less. Furthermore, the inventors of the present invention have found that the generation of metal bubbles can be suppressed by setting the hydrogen sintering temperature to 400 ° C. or more and 450 ° C. or less for the hydrogen sintering treatment. The details of how the metal bubble generation frequency, the film thickness of the upper light-shielding Al film, the film stress of the intervening film, and the hydrogen sintering temperature are related to each other will be described below.

(Relationship between film thickness of upper light-shielding Al film and frequency of occurrence of metal bubbles)
FIG. 11 is a diagram for explaining the relationship between the film thickness of the upper light-shielding Al film of the solid-state imaging device and the metal bubble occurrence frequency according to each embodiment of the present invention. The inventor of the present invention sets the film stress of the upper light-shielding Al film by setting the film stress of the intervening film to Tensile 6.0E8 Pa (that is, the interstitial film tensile stress is 6.0E8 Pa), the hydrogen sintering temperature to 420 ° C. Experiments were conducted on the relationship with the frequency of occurrence of metal bubbles, and the experimental results shown in FIG. 11 were obtained.

That is, as shown in FIG. 11, when the thickness of the upper Al light shielding film 12 is 50 nm or more, the frequency of occurrence of metal bubbles (compared to the conventional) increases as the thickness of the upper Al light shielding film 12 is increased. ing. However, when the film thickness of the upper Al light shielding film 12 is 50 nm or more and 90 nm or less, the film of the upper Al light shielding film 12 is larger than the case where the film thickness of the upper Al light shielding film 12 is larger than 90 nm. It was confirmed that the rate of increase in the frequency of occurrence of metal bubbles (compared to the prior art) with increasing thickness was moderate. In addition, when the film thickness of the upper Al light shielding film 12 is thicker than 125 nm, it is confirmed that the frequency of occurrence of metal bubbles (compared to the prior art) increases rapidly as the film thickness of the upper Al light shielding film 12 increases. did. Furthermore, when the film thickness of the upper Al light shielding film 12 is less than 50 nm, the transmittance of incident light is increased and the light shielding property is deteriorated.

Therefore, the inventors of the present invention have found that the thickness of the upper Al light shielding film 12 is preferably 50 nm or more and 125 nm or less. Further, the inventors of the present invention have found that the film thickness of the upper Al light shielding film 12 is 50 nm or more and more preferably 90 nm or less.

When the film thickness of the upper Al light shielding film 12 is 50 nm or more and 125 nm or less, it is possible to reduce the generation probability of holes existing in the upper Al light shielding film 12 and suppress the generation of metal bubbles. it can. Further, when the film thickness of the upper Al light shielding film 12 is 50 nm or more and 90 nm or less, the generation probability of vacancies in the upper Al light shielding film 12 is further reduced, and the generation of metal bubbles is further reduced. It can be effectively suppressed.

(Relationship between interstitial film stress and metal bubble frequency)
FIG. 12 is a diagram for explaining the relationship between the intervening film stress and the frequency of occurrence of metal bubbles. For convenience of explanation, terms and the like regarding the intervening film stress (film stress of the intervening film) will be described first.

When a thin film is formed on a flat substrate (wafer), mechanical stress (film stress) is generated in the film due to the difference between the thermal expansion coefficient (thermal expansion coefficient) of the film and the thermal expansion coefficient of the substrate. To do. In order to relieve the film stress, the substrate is warped. Here, the direction in which the periphery of the substrate is pulled is stretched (tensile), and the direction in which the periphery of the substrate is suppressed is compressed (compressive). The film stress (film stress) is based on the substrate (wafer), when it acts in the direction of pulling the periphery of the substrate, and when it acts in the direction of restraining the periphery of the substrate, it is compressed. It is called stress (Compressive Stress).

The inventor of the present invention conducted an experiment on the relationship between the film stress of the intervening film and the frequency of occurrence of metal bubbles with the film thickness of the upper Al light shielding film 12 being 85 nm and the hydrogen sintering temperature being 420 ° C. The experimental results shown are obtained. That is, as shown in FIG. 12, the film stress (film stress) of the intervening film is Tensile (that is, film stress in the direction of pulling the periphery), 5.0E8 Pa or more, 7.0E8 Pa or less (5.0E9 dyne / The inventor of the present invention has found that it is preferable to set it to cm ² or more and 7.0E9 dyne / cm ² or less. In other words, the inventors of the present invention have found that the tensile stress of the intervening film is preferably 5.0E8 Pa or more and 7.0E8 Pa or less.

As shown in FIG. 12, when the tensile stress of the intervening film was made smaller than 5.0E8 Pa, the frequency of occurrence of metal bubbles (compared to the conventional) increased as the tensile stress of the intervening film was reduced. On the other hand, when the tensile stress of the intervening film is 5.0E8 Pa or more and 7.0E8 Pa or less, the frequency of occurrence of metal bubbles (compared to the conventional) is not increased.

(Relationship between hydrogen sintering temperature and metal bubble frequency)
FIG. 13 is a diagram for explaining the relationship between the hydrogen sintering temperature and the metal bubble occurrence frequency. The inventor of the present invention sets the film thickness of the upper Al light shielding film 12 to 85 nm, sets the film stress of the intervening film to Tensile 6.0E8 Pa (that is, sets the tensile stress of the intervening film to 6.0E8 Pa), and performs the hydrogen sintering treatment temperature. Experiments were performed on the relationship between (hydrogen sinter temperature when performing hydrogen sinter treatment) and metal bubble generation frequency, and experimental results shown in FIG. 13 were obtained.

That is, as shown in FIG. 13, when the hydrogen sintering temperature is set to 420 ° C. or higher, the frequency of occurrence of metal bubbles (compared to the conventional technology) increases as the hydrogen sintering temperature is increased.

However, when the hydrogen sintering temperature is 420 ° C. or higher and 450 ° C. or lower, the frequency of occurrence of metal bubbles accompanying the increase in the hydrogen sintering temperature (as compared to when the hydrogen sintering temperature is higher than 450 ° C.) It was confirmed that the rate of increase) was moderate. On the other hand, when the hydrogen sintering temperature was higher than 450 ° C., it was confirmed that the frequency of occurrence of metal bubbles (compared to the prior art) increased rapidly as the hydrogen sintering temperature increased.

In addition, the inventors of the present invention show that when the hydrogen sintering process is performed at a temperature higher than 450 ° C., the stress applied to the light-shielding portion is increased compared to when the hydrogen sintering temperature is set to 450 ° C. or lower. It was confirmed that the occurrence frequency of metal bubbles increased.

Furthermore, when the hydrogen sintering temperature is less than 400 ° C., the device characteristics of the solid-state imaging device are deteriorated due to white scratches and dark current.

Therefore, the inventors of the present invention have found that the hydrogen sintering temperature is preferably 400 ° C. or higher and 450 ° C. or lower.

(Details of manufacturing method)
Below, the manufacturing method of the solid-state image sensor 100 is demonstrated in detail using FIGS. 4-6. As described above, the solid-state imaging device 100 has the same configuration as that of a general CMOS image sensor except for the configuration related to the light shielding unit 170. The manufacturing method of the solid-state imaging device 100 is also the same as the manufacturing method of the configuration of a general CMOS image sensor because the manufacturing method of the configuration other than the light shielding unit 170 is the same as that of the general CMOS type image sensor.

FIG. 4 is a cross-sectional view illustrating a method for manufacturing the solid-state imaging device 100. FIG. 4A shows a part of the cross-sectional structure of the solid-state imaging device 100, and the through holes 113 are formed based on a manufacturing method similar to a general CMOS image sensor manufacturing method. Yes. In the method for manufacturing the solid-state imaging device 100, after forming the through hole 113, the third-layer Al wiring 10, which is the lower Al light shielding film, the intervening film 11, and the upper Al light shielding film 12 are formed. Hereinafter, the manufacturing method of the light shielding part 170, more specifically, the manufacturing method of each of the third layer Al wiring 10, the intervening film 11, and the upper layer Al light shielding film 12 will be described in detail.

First, as the lower Al light shielding film provided on the side closest to the semiconductor substrate 120 in the light shielding portion 170, the third layer Al wiring 10 which is an Al wiring is formed. The third layer Al wiring 10 was formed of aluminum or an aluminum alloy containing aluminum as a main component, and the film thickness of the third layer Al wiring 10 was 150 nm or more and 250 nm or less.

Next, the intervening film 11 is formed using titanium nitride (TiN). The thickness of the intervening film 11 was 100 nm. At this time, in order to suppress the metal bubble occurrence frequency and avoid the deterioration of the light shielding property, the film stress of the intervening film 11 is set to Tensile of 5.0E8 Pa or more and 7.0E8 Pa or less as shown in FIG. Is preferred. In this embodiment, the intervening film 11 is formed by setting the film stress of the intervening film 11 to Tensile 6.0E8 Pa.

The inventor of the present invention has found that the generation of metal bubbles can be suppressed by reducing the difference between the thermal expansion coefficient (thermal expansion coefficient) of the upper Al light shielding film 12 and the thermal expansion coefficient of the intervening film 11. did. Specifically, the intervening film 11 and the upper Al light shielding film 12 are arranged such that the direction of the film stress of the intervening film 11 and the direction of the film stress of the upper Al light shielding film 12 are both in the direction of extension (Tensile). It means that was formed. Specifically, the interstitial film 11 has a film stress of Tensile 5.0E8 Pa or more and 7.0E8 Pa or less, that is, the interstitial film 11 has a tensile stress of 5.0E8 Pa or more and 7.0E8 Pa or less. It was discovered that the formation of the intervening film 11 can suppress the generation of metal bubbles.

Although the generation mechanism of the metal bubble is not clear, since the difference between the thermal expansion coefficient of the intervening film 11 and the thermal expansion coefficient of the upper Al light shielding film 12 is reduced, the stress on the upper Al light shielding film 12 is reduced and metal voids are generated. It is thought that it is hard to generate. Note that the gas flow rate, pressure, temperature, and film thickness at the time of forming the intervening film 11 are controlled so that the film stress of the intervening film 11 is set to Tensile 5.0E8 Pa or more and 7.0E8 Pa or less.

Finally, as the upper Al light shielding film in the light shielding part 170, the upper Al light shielding film 12 was formed using aluminum or an aluminum alloy mainly composed of aluminum. The film thickness of the upper Al light shielding film 12 was 70 nm.

Here, the thickness of the upper Al light shielding film 12 is preferably 50 nm or more and 125 nm or less, and more preferably 50 nm or more and 90 nm or less. When the film thickness of the upper Al light shielding film 12 is 125 nm or less, the generation probability of vacancies existing in the upper Al light shielding film 12 is reduced, and the generation of metal bubbles can be suppressed. However, when the thickness of the upper Al light shielding film 12 is smaller than 50 nm, the transmittance of incident light is increased and the light shielding property is deteriorated.

Next, as shown in FIG. 4B, a resist 18 for leaving the upper Al light shielding film 12 and the intervening film 11 is formed. Thereafter, as shown in FIG. 4C, an upper Al light shielding film 12 and an intervening film 11 are formed in the OB pixel region B by using photolithography and dry etching.

FIG. 5 is a cross-sectional view illustrating a manufacturing method of the solid-state image sensor 100, and is a cross-sectional view illustrating a manufacturing process of the solid-state image sensor 100 following the manufacturing process illustrated in FIG. As shown in FIG. 5A, the third-layer Al wiring 10 is left in the effective pixel area A, the third-layer Al wiring 10, the intervening film 11, and the upper-layer Al light shielding film in the OB pixel area B. And a resist 19 for leaving 12 is formed. At that time, a resist 19 is also formed around the upper Al light shielding film 12 and the interposition film 11 in order to leave the upper Al light shielding film 12 and the interposition film 11 in the OB pixel region B with certainty. Thereafter, by using photolithography and dry etching, as shown in FIG. 5B, a third-layer Al wiring 10 is formed as a lower Al light shielding film in the OB pixel region B. Further, as shown in FIG. 5C, an interlayer insulating film 13 is formed by HDP film formation and CMP process.

FIG. 6 is a cross-sectional view illustrating a manufacturing method of the solid-state image sensor 100, and is a cross-sectional view illustrating a manufacturing process of the solid-state image sensor 100 following the manufacturing process illustrated in FIG. As shown in FIG. 6, after the manufacturing process shown in FIG. 5C, a passivation film 14 is further formed by a general CMOS image sensor manufacturing method, and a hydrogen sintering process is performed.

The hydrogen sintering process can be performed any time after the formation of the Al wiring layer structure. However, by performing the hydrogen sintering process after forming the passivation film 14, the following effects are obtained. That is, by performing the hydrogen sintering process after the formation of all the Al wiring layer structures, the effect of the hydrogen sintering process can be obtained for all the processes.

The hydrogen sintering process is performed after the passivation film 14 is formed, but may be performed in any process as long as it is after the formation of the light shielding portion 170 having a multilayer structure. At this time, in order to suppress the frequency of occurrence of metal bubbles and avoid a decrease in light shielding properties, it is preferable that the hydrogen sintering temperature be 400 ° C. or higher and 450 ° C. or lower.

The inventor of the present invention, when performing the hydrogen sintering process with the hydrogen sintering temperature higher than 450 ° C., the stress applied to the light shielding portion 170 is increased as compared with the case where the hydrogen sintering temperature is set to 450 ° C. or lower. It was confirmed that the occurrence frequency of metal bubbles increased. When the frequency of occurrence of metal bubbles increases, the light shielding property of the light shielding unit 170 deteriorates. On the other hand, when the hydrogen sintering temperature is less than 400 ° C., the device characteristics of the solid-state imaging device 100 deteriorate due to white scratches and dark current. Accordingly, the hydrogen sintering temperature is preferably 400 ° C. or higher and 450 ° C. or lower.

By controlling the hydrogen sintering temperature in the hydrogen sintering process performed after forming the light shielding portion 170 having the multilayer structure, the stress applied to the upper AL light shielding film 12 is reduced to suppress metal voids, and the light shielding property of the OB pixel region B is improved. It is improving.

The inventors of the present invention performed the hydrogen sintering treatment at a hydrogen sintering treatment temperature of 420 ° C. in consideration of the influence on device characteristics other than “avoidance of deterioration in light shielding”.

After that, the color filter 15 is formed so as to have the desired spectral characteristics of Red, Green, and Blue, and the protective film 16 and the microlens 17 are formed to complete the solid-state imaging device 100.

(Outline of manufacturing method)
Next, the manufacturing method of the solid-state imaging device 100 described so far will be described in an organized manner with reference to FIG.

FIG. 7 is a flowchart for explaining the outline of the manufacturing method of the solid-state imaging device 100. As shown in FIG. 7, the method for manufacturing the solid-state imaging device 100 includes the step of controlling the film stress of the intervening film to form the intervening film (S100: intervening film forming step) and the thickness of the upper aluminum light-shielding film. Controlling to form an upper aluminum light shielding film (S200: upper aluminum light shielding film forming step), controlling a hydrogen sintering temperature to perform hydrogen sintering (S300: hydrogen sintering process execution step), including.

Here, in the intervening film formation step (S100), the intervening film 11 is formed by controlling the tensile stress of the intervening film 11 to be 5.0E8 Pa or more and 7.0E8 Pa or less.

In the upper-layer aluminum light-shielding film forming step (S200), the upper-layer Al light-shielding film 12 (upper-layer light-shielding film) is controlled so that the film thickness of the upper-layer Al light-shielding film 12 is 50 nm or more and 125 nm or less. It is made of an aluminum alloy containing as a main component. In particular, in the upper-layer aluminum light-shielding film forming step (S200), the upper-layer Al light-shielding film 12 is formed by controlling the film thickness of the upper-layer Al light-shielding film 12 (upper light-shielding film) to be 50 nm or more and 90 nm or less. Is preferred.

Further, in the hydrogen sintering process execution step (S300), after forming the light shielding part 170, the hydrogen sintering process is performed at a hydrogen sintering temperature of 400 ° C. or higher and 450 ° C. or lower.

The manufacturing method of the solid-state imaging device 100 described so far can be organized as follows. That is, the manufacturing method of the solid-state imaging device 100 is a manufacturing method of the solid-state imaging device including the light-shielding unit 170 that shields the OB region B formed on the semiconductor substrate 120 (substrate). In order from the side close to 120, the third layer Al wiring 10 (lower light shielding film), the intervening film 11, and the upper aluminum shielding film 12 (upper light shielding film) are made of aluminum or an aluminum alloy containing aluminum as a main component. Lower layer light shielding film forming step for forming third layer Al wiring 10 and upper layer for forming upper aluminum light shielding film 12 having a film thickness of 50 nm or more and 125 nm or less by aluminum or an aluminum alloy containing aluminum as a main component A light shielding film forming step (S200). In the upper light-shielding film forming step (S200), it is preferable to form the upper aluminum light-shielding film 12 having a thickness smaller than that of the intervening film 11.

In the manufacturing method of the solid-state imaging device 100, the tensile stress of the intervening film 11 is 5.0E8 Pa or more and 7.0E8 Pa or less after the lower layer light shielding film formation step and before the upper layer light shielding film formation step (S200). In addition, an intervening film forming step (S100) for forming the intervening film 11 is further included.

The method for manufacturing the solid-state imaging device 100 further includes a hydrogen sintering process execution step (S300) of performing a hydrogen sintering process at a hydrogen sintering temperature of 400 ° C. or higher and 450 ° C. or lower after the light shielding portion 170 is formed.

Regarding the light-shielding portion 170 having a multilayer structure using the Al wiring layer used for the peripheral circuit, (1) the stress of the intervening film 11 immediately below the upper Al light-shielding film 12 is set to a Tensile of 5.0E8 Pa or more and 7.0E8 Pa or less. (2) The upper Al light shielding film 12 is formed with a film thickness in the range of 50 nm to 125 nm, and (3) the hydrogen sintering temperature is 450 ° C. or lower, thereby shielding light from metal bubbles. It is possible to avoid a decrease in performance, and to minimize an increase in the distance between the semiconductor substrate 120 and the lens 17.

Further, by forming the third layer Al wiring 10 as the lowermost layer of the light shielding portion 170 having a multilayer structure in the OB pixel region B, the following effects are obtained. That is, the second layer Al wiring 111 and the first layer Al wiring 108 can be formed under the third layer Al wiring 10. That is, the second-layer Al wiring 111 and the first-layer Al wiring 108 below the third-layer Al wiring 10 in the OB pixel region B are connected to the light-receiving unit 101 and the FD unit 102 for transmitting signals. As wiring, it can be used in circuit design. Considering the degree of freedom in circuit design using Al wiring for signal transmission to the light receiving unit 101 and the FD unit 102, it is most preferable to provide the light shielding unit 170 having a multilayer structure in the uppermost layer.

[Embodiment 2]
The following will describe another embodiment of the present invention with reference to FIG. For convenience of explanation, members having the same functions as those described in the embodiment are given the same reference numerals, and descriptions thereof are omitted.

FIG. 8 is a cross-sectional view of the solid-state imaging device 200 according to Embodiment 2 of the present invention. The solid-state image sensor 200 is, for example, a CMOS image sensor. First, the outline of the solid-state imaging device 200 will be described as follows.

That is, the solid-state imaging device 200 is a solid-state imaging device including a light shielding unit 270 that shields the OB region B formed on the semiconductor substrate 120 (substrate), and the light shielding unit 270 is sequentially arranged from the side closer to the semiconductor substrate 120. , Second layer Al wiring 111 (lower layer light shielding film), intervening film 11 and upper layer aluminum light shielding film 12 (upper layer light shielding film). Second layer Al wiring 111 and upper layer aluminum light shielding film 12 are made of aluminum or aluminum. The upper aluminum light-shielding film 12 has a thickness of 50 nm or more and 125 nm or less.

Next, the outline of the method for manufacturing the solid-state imaging device 200 will be described as follows. That is, the manufacturing method of the solid-state imaging device 200 is a manufacturing method of the solid-state imaging device including the light-shielding unit 270 that shields the OB region B formed on the semiconductor substrate 120 (substrate). In order from the side close to 120, the second layer Al wiring 111 (lower light shielding film), the intervening film 11, and the upper aluminum shielding film 12 (upper light shielding film) are used. Lower layer light shielding film forming step for forming second-layer Al wiring 111, and upper layer for forming upper aluminum light shielding film 12 having a thickness of 50 nm or more and 125 nm or less with aluminum or an aluminum alloy containing aluminum as a main component A light shielding film forming step (S200). In particular, in the upper-layer aluminum light-shielding film forming step (S200), the upper-layer Al light-shielding film 12 is formed by controlling the film thickness of the upper-layer Al light-shielding film 12 (upper light-shielding film) to be 50 nm or more and 90 nm or less. Is preferred.

Note that the differences between the solid-state image sensor 100 and the solid-state image sensor 200 are summarized as follows. That is, in the light shielding unit 170 of the solid-state imaging device 100, the third layer AL wiring 10 is provided on the side closest to the semiconductor substrate 120, whereas in the light shielding unit 270 of the solid-state imaging device 200, The second layer Al wiring 111 is provided on the side closest to the semiconductor substrate 120. Except for this point, the solid-state imaging device 100 and the solid-state imaging device 200 have substantially the same configuration. Therefore, in the following description, this point will be mainly described, and the same configuration as that described in the above embodiment will be described. Description of is omitted.

Hereinafter, details of the solid-state imaging device 200 and the manufacturing method thereof will be described. However, since the solid-state imaging device 200 has the same configuration as that of a general CMOS image sensor except for the configuration related to the light shielding unit 270, the details are omitted.

As shown in FIG. 8, the solid-state imaging device 200 includes a gate insulating film 104, a charge transfer electrode 105 made of a polysilicon electrode, an interlayer insulating film 106, a through-hole 107, a first layer Al wiring 108, an interlayer insulation. A film 109 and a through hole 110 are sequentially formed. Thereafter, a second layer Al wiring 111, an intervening film 11, and an upper Al light shielding film 12 are formed.

The second-layer Al wiring 111 is an Al wiring as a lower-layer Al light-shielding film provided on the side closest to the semiconductor substrate 120 in the light-shielding portion 270 of the OB pixel region B, and is a film of the second-layer Al wiring 111. The thickness was 150 nm or more and 250 nm or less. Further, the solid-state imaging device 200 uses titanium nitride (TiN) as the intervening film 11, and the intervening film 11 has a thickness of 100 nm. The film thickness of the upper Al light shielding film 12 was 70 nm.

That is, in the solid-state imaging device 200, the thickness of the intervening film 11 is smaller than the thickness of the second layer Al wiring 111 (lower Al light shielding film), and the thickness of the upper Al light shielding film 12 is the thickness of the intervening film 11. Thinner than.

However, the film thickness of the upper Al light-shielding film 12 may be 50 nm or more and 125 nm or less, and it is not essential that the film thickness of the upper Al light-shielding film 12 is thinner than the intervening film 11 having a film thickness of 100 nm. Absent. For example, the thickness of the upper Al light shielding film 12 may be 125 nm, and the thickness of the intervening film 11 may be 100 nm.

In forming the intervening film 11, in order to suppress the occurrence frequency of metal bubbles and avoid the deterioration of the light shielding property, the film stress of the intervening film 11 is set to Tensile of 5.0E8 Pa or higher, 7 as shown in FIG. 0.0E8 Pa or less is preferable. That is, it is preferable to form the intervening film 11 so that the tensile stress of the intervening film 11 is 5.0E8 Pa or more and 7.0E8 Pa or less. By setting the film stress of the intervening film 11 as described above, the generation of metal bubbles can be suppressed. That is, the difference between the thermal expansion coefficient of the upper Al light shielding film 12 and the thermal expansion coefficient of the intervening film 11 is reduced, and the direction of the film stress of the intervening film 11 and the direction of the film stress of the upper Al light shielding film 12 are both extended ( By forming the intervening film 11 and the upper Al light shielding film 12 so as to be in the direction of Tensile, the generation of metal bubbles can be suppressed. Note that the gas flow rate, pressure, temperature, and film thickness at the time of forming the intervening film 11 are controlled so that the film stress of the intervening film 11 is set to Tensile 5.0E8 Pa or more and 7.0E8 Pa or less. In this embodiment, the intervening film 11 is formed by setting the film stress of the intervening film 11 to Tensile 6.0E8 Pa.

Further, in order to suppress the metal bubble generation frequency and avoid the deterioration of the light shielding property, the film thickness of the upper Al light shielding film 12 is preferably 50 nm or more and 125 nm or less as shown in FIG. When the film thickness of the upper Al light shielding film 12 is 125 nm or less, vacancies existing in the upper Al light shielding film 12 can be reduced and generation of metal bubbles can be suppressed. However, when the thickness of the upper Al light shielding film 12 is less than 50 nm, the transmittance of incident light is increased and the light shielding property is deteriorated. Therefore, the thickness of the upper Al light shielding film 12 is preferably 50 nm or more and 125 nm or less.

After the second layer Al wiring 111, the intervening film 11, and the upper layer Al light shielding film 12 are formed, the second layer Al wiring 111 is left in the effective pixel region A by using photolithography and dry etching, and the OB pixel In the region B, the second-layer Al wiring 111, the intervening film 11, and the upper-layer Al light shielding film 12 are left. The second-layer Al wiring 111 that remains in the OB pixel region B is formed as a lower-layer Al light-shielding film provided on the light-shielding portion 270 on the side closest to the semiconductor substrate 120.

Thereafter, an interlayer insulating film 112 is formed by HDP film formation and CMP process. Then, using a general CMOS image sensor manufacturing method, the through hole 113, the third-layer AL wiring 10, the interlayer insulating film 13, and the passivation film 14 are formed, and hydrogen sintering is performed.

The hydrogen sintering process is performed after the passivation film 14 is formed, but may be performed in any process as long as it is after the formation of the light-shielding portion 270 having a multilayer structure. At this time, in order to suppress the frequency of occurrence of metal bubbles and avoid a decrease in light shielding properties, it is preferable that the hydrogen sintering temperature be 400 ° C. or higher and 450 ° C. or lower.

When the hydrogen sintering temperature is higher than 450 ° C., the light shielding performance of the light shielding portion 270 is deteriorated as compared with the case where the hydrogen sintering temperature is 450 ° C. or lower. On the other hand, when the hydrogen sintering temperature is less than 400 ° C., the device characteristics of the solid-state imaging device 200 deteriorate due to white scratches and dark current. Accordingly, the hydrogen sintering temperature is preferably 400 ° C. or higher and 450 ° C. or lower. In manufacturing the solid-state imaging device 200, the inventor of the present invention performed the hydrogen sintering process at a hydrogen sintering process temperature of 420 ° C. in consideration of the influence on device characteristics other than “avoidance of a decrease in light shielding”.

After that, the color filter 15 is formed so as to have red, green, and blue spectral requirements, and the protective film 16 and the microlens 17 are formed to complete the solid-state imaging device 200.

Regarding the light-shielding portion 270 having a multilayer structure using an Al wiring layer used for the peripheral circuit, (1) the intervening film 11 immediately below the upper Al light-shielding film 12 has a thickness of 5.0E8 Pa or more of Tensile. (2) forming the upper Al light shielding film 12 by controlling the film thickness of the upper Al light shielding film 12 to be 50 nm or more and 125 nm or less; and (3) By performing the hydrogen sinter treatment at a hydrogen sinter temperature of 450 ° C. or lower, it is possible to avoid a reduction in light shielding property due to the generation of metal bubbles, and between the semiconductor substrate 120 (substrate) and the lens 17. The increase in distance can be minimized.

Further, by forming the second layer Al wiring 111 as the Al light shielding film in the OB pixel region B, the following effects are obtained. That is, the first layer Al wiring 108 formed immediately below the second layer Al wiring 111 is below the second layer Al wiring 111 for signal transmission to the light receiving unit 101 and the FD unit 102. The Al wiring can be used in circuit design. Therefore, the solid-state imaging device 200 can improve the degree of freedom in circuit design using Al wiring for signal transmission to the light receiving unit 101 and the FD unit 102. Further, the solid-state imaging device 200 can be provided with the light-shielding portion 370 near the light-receiving portion 101 as compared with the first embodiment (solid-state imaging device 100), and the light-shielding performance can be improved as compared with the first embodiment.

[Embodiment 3]
The following will describe another embodiment of the present invention with reference to FIG. For convenience of explanation, members having the same functions as those described in the embodiment are given the same reference numerals, and descriptions thereof are omitted.

FIG. 9 is a cross-sectional view of a solid-state imaging device 300 according to Embodiment 3 of the present invention. The solid-state image sensor 300 is, for example, a CMOS image sensor. First, the outline of the solid-state imaging device 300 will be described as follows.

That is, the solid-state imaging device 300 is a solid-state imaging device including a light shielding unit 370 that shields the OB region B formed on the semiconductor substrate 120 (substrate), and the light shielding unit 370 is sequentially arranged from the side closer to the semiconductor substrate 120. , First layer Al wiring 108 (lower layer light shielding film), intervening film 11 and upper layer aluminum light shielding film 12 (upper layer light shielding film). First layer Al wiring 108 and upper layer aluminum light shielding film 12 are made of aluminum or aluminum. The upper aluminum light-shielding film 12 has a thickness of 50 nm or more and 125 nm or less.

Next, the outline of the manufacturing method of the solid-state imaging device 300 will be described as follows. That is, the manufacturing method of the solid-state imaging device 300 is a manufacturing method of a solid-state imaging device including a light shielding unit 370 that shields the OB region B formed on the semiconductor substrate 120 (substrate), and the light shielding unit 370 is a semiconductor substrate. In order from the side close to 120, the first layer Al wiring 108 (lower light shielding film), the intervening film 11, and the upper aluminum shielding film 12 (upper light shielding film) are made of aluminum or an aluminum alloy containing aluminum as a main component. Lower-layer light-shielding film forming step for forming first-layer Al wiring 108, and upper layer for forming upper-layer aluminum light-shielding film 12 having a thickness of 50 nm or more and 125 nm or less with aluminum or an aluminum alloy containing aluminum as a main component A light shielding film forming step (S200). In particular, in the upper-layer aluminum light-shielding film forming step (S200), the upper-layer Al light-shielding film 12 is formed by controlling the film thickness of the upper-layer Al light-shielding film 12 (upper light-shielding film) to be 50 nm or more and 90 nm or less. Is preferred.

Note that the differences between the solid-state image sensor 100 and the solid-state image sensor 300 are summarized as follows. That is, in the light shielding portion 170 of the solid-state imaging device 100, the third layer Al wiring 10 is provided on the side closest to the semiconductor substrate 120, whereas in the light shielding portion 370 of the solid-state imaging device 300, The first layer Al wiring 108 is provided on the side closest to the semiconductor substrate 120. Except for this point, the solid-state imaging device 100 and the solid-state imaging device 300 have substantially the same configuration. Therefore, in the following description, the description will be focused on this point, and the same configuration as that described in the first embodiment. Description of is omitted.

Hereinafter, details of the solid-state imaging device 300 and the manufacturing method thereof will be described. However, the configuration of the solid-state imaging device 300 is the same as that of a general CMOS image sensor except for the configuration related to the light shielding unit 370, and thus the details are omitted.

As shown in FIG. 9, in the solid-state imaging device 300, first, a gate insulating film 104, a charge transfer electrode 105 made of a polysilicon electrode, an interlayer insulating film 106, and a through hole 107 are sequentially formed. Thereafter, the first layer Al wiring 108, the intervening film 11, and the upper Al light shielding film 12 are formed.

The first-layer Al wiring 108 is an Al wiring as a lower-layer Al light-shielding film provided on the side closest to the semiconductor substrate 120 in the light-shielding portion 370 of the OB pixel region B, and is a film of the first-layer Al wiring 108. The thickness was 150 nm or more and 250 nm or less. The solid-state imaging device 300 uses titanium nitride (TiN) as the intervening film 11, and the intervening film 11 has a thickness of 100 nm. The film thickness of the upper Al light shielding film 12 was 70 nm.

That is, in the solid-state imaging device 300, the thickness of the intervening film 11 is smaller than the thickness of the first layer Al wiring 108 (lower Al light shielding film), and the thickness of the upper Al light shielding film 12 is the thickness of the intervening film 11. Thinner than.

After forming the first-layer Al wiring 108, the intervening film 11, and the upper-layer Al light-shielding film 12, the first-layer Al wiring 108 is left in the effective pixel region A by using photolithography and dry etching, and the OB pixel In the region B, the first-layer Al wiring 108, the intervening film 11, and the upper-layer Al light shielding film 12 are left. The first layer Al wiring 108 remaining in the OB pixel region B is formed as a lower Al light shielding film provided on the light shielding portion 370 on the side closest to the semiconductor substrate 120.

Thereafter, an interlayer insulating film 109 is formed by HDP film formation and CMP process. Then, using a general CMOS image sensor manufacturing method, the through hole 110, the second layer wiring 111, the interlayer insulating film 112, the through hole 113, the third layer AL wiring 10, the interlayer insulating film 13, and the passivation. A film 14 is formed and hydrogen sintering is performed.

The hydrogen sintering process is performed after the passivation film 14 is formed, but may be performed in any process as long as it is after the formation of the light shielding portion 370 having a multilayer structure. At this time, in order to suppress the frequency of occurrence of metal bubbles and avoid a decrease in light shielding properties, it is preferable that the hydrogen sintering temperature be 400 ° C. or higher and 450 ° C. or lower.

When the hydrogen sintering temperature is higher than 450 ° C., the light shielding performance of the light shielding portion 370 is deteriorated as compared with the case where the hydrogen sintering temperature is 450 ° C. or lower. On the other hand, when the hydrogen sintering temperature is lower than 400 ° C., the device characteristics of the solid-state imaging device 300 deteriorate due to white scratches and dark current. Accordingly, the hydrogen sintering temperature is preferably 400 ° C. or higher and 450 ° C. or lower. In manufacturing the solid-state imaging device 300, the inventor of the present invention performed the hydrogen sintering process at a hydrogen sintering temperature of 420 ° C. in consideration of the influence on device characteristics other than “avoidance of light shielding performance reduction”.

After that, the color filter 15 is formed so as to have red, green, and blue spectral requirements, and the protective film 16 and the microlens 17 are formed to complete the solid-state imaging device 300.

Regarding the light-shielding portion 370 having a multilayer structure using an Al wiring layer used for the peripheral circuit, (1) the intervening film 11 immediately below the upper Al light-shielding film 12 is set to 5.0E8 Pa or more when the film stress of the intervening film 11 is Tensile, (2) forming the upper Al light shielding film 12 by controlling the film thickness of the upper Al light shielding film 12 to be 50 nm or more and 125 nm or less; and (3) By performing the hydrogen sinter treatment at a hydrogen sinter temperature of 450 ° C. or lower, it is possible to avoid a reduction in light shielding property due to the generation of metal bubbles, and between the semiconductor substrate 120 (substrate) and the lens 17. The increase in distance can be minimized.

Further, by forming the first-layer Al wiring 108 as the Al light-shielding film in the OB pixel region B, the circuit design using the Al wiring is more than that in the first embodiment (solid-state imaging device 100) and the second embodiment (solid-state imaging device 200). However, in the solid-state imaging device 300, the light shielding unit 370 can be provided closest to the light receiving unit 101, and the light shielding performance can be further improved.

[Embodiment 4]
The following will describe another embodiment of the present invention with reference to FIG. For convenience of explanation, members having the same functions as those described in the embodiment are given the same reference numerals, and descriptions thereof are omitted.

FIG. 10 is a cross-sectional view illustrating a method for manufacturing the solid-state imaging device 400 according to Embodiment 4 of the present invention. The solid-state image sensor 400 is, for example, a CCD image sensor. First, the outline of the solid-state imaging device 400 will be described as follows.

That is, the solid-state imaging device 400 is a solid-state imaging device including a light shielding unit 470 that shields the OB region B formed on the semiconductor substrate 120 (substrate), and the light shielding unit 470 is in order from the side closer to the semiconductor substrate 120. , Lower Al light shielding film 115 (lower light shielding film), intervening film 11, and upper aluminum light shielding film 12 (upper layer light shielding film). Lower Al light shielding film 115 and upper aluminum light shielding film 12 are mainly composed of aluminum or aluminum. The upper aluminum light shielding film 12 is made of an aluminum alloy and has a thickness of 50 nm or more and 125 nm or less.

Next, the outline of the manufacturing method of the solid-state imaging device 400 will be described as follows. That is, the manufacturing method of the solid-state imaging device 400 is a manufacturing method of the solid-state imaging device including the light-shielding unit 470 that shields the OB region B formed on the semiconductor substrate 120 (substrate). In order from the side close to 120, the lower Al light shielding film 115 (lower light shielding film), the intervening film 11, and the upper aluminum light shielding film 12 (upper light shielding film) are made of aluminum or an aluminum alloy containing aluminum as a main component, and the lower Al light shielding. A lower light-shielding film forming step for forming the film 115, and an upper light-shielding film forming step for forming the upper aluminum light-shielding film 12 of aluminum or an aluminum alloy containing aluminum as a main component and having a film thickness of 50 nm or more and 125 nm or less. (S200). In particular, in the upper-layer aluminum light-shielding film forming step (S200), the upper-layer Al light-shielding film 12 is formed by controlling the film thickness of the upper-layer Al light-shielding film 12 (upper light-shielding film) to be 50 nm or more and 90 nm or less. Is preferred.

The differences between the solid-state image sensor 100 and the solid-state image sensor 400 can be summarized as follows. That is, in the light shielding unit 170 of the solid-state imaging device 100, the third layer Al wiring 10 is provided on the side closest to the semiconductor substrate 120, whereas in the light shielding unit 470 of the solid-state imaging device 400, A lower Al light shielding film 115 is provided on the side closest to the semiconductor substrate 120. Except for this point, the solid-state imaging device 100 and the solid-state imaging device 400 have substantially the same configuration. Therefore, in the following description, this point will be mainly described and the same configuration as that described in the first embodiment will be described. Description of is omitted.

Hereinafter, details of the solid-state imaging device 400 and the manufacturing method thereof will be described. However, the configuration of the solid-state imaging device 400 is the same as that of a general CCD type image sensor except for the configuration related to the light shielding unit 470, and therefore the details are omitted.

As shown in FIG. 10A, in the method of manufacturing the solid-state imaging device 400, first, the light receiving portion 101, the gate insulating film 104 (gate oxide film 104B), the charge transfer electrode 105 made of a polysilicon electrode, the gate A tungsten (W) light-shielding film 114B, an interlayer insulating film 106, and a through hole (peripheral circuit portion, not shown) for sequentially suppressing noise generated by light incidence on the oxide film 104B are formed.

Thereafter, as shown in FIG. 10B, an Al film for wiring (peripheral circuit portion, not shown) and a lower Al light shielding film 115 in the OB pixel region B are simultaneously deposited, and the intervening film 11 and upper Al light shielding are further deposited. A film 12 is formed.

The lower Al light shielding film 115 is an Al wiring as a lower Al light shielding film provided on the side closest to the semiconductor substrate 120 in the light shielding portion 470 of the OB pixel region B, and the film thickness of the lower Al light shielding film 115 is 150 nm. As mentioned above, it was set to 250 nm or less. The solid-state imaging device 400 uses titanium nitride (TiN) as the intervening film 11, and the intervening film 11 has a thickness of 100 nm. The film thickness of the upper Al light shielding film 12 was 70 nm.

That is, in the solid-state imaging device 400, the thickness of the intervening film 11 is smaller than the thickness of the lower Al light shielding film 115 (lower Al light shielding film), and the thickness of the upper Al light shielding film 12 is larger than the thickness of the intervening film 11. thin.

Next, by using photolithography and dry etching, Al wiring (not shown) is left in the peripheral circuit portion C, and in the OB pixel region B, the lower Al light shielding film 115, the intervening film 11, and the upper Al light shielding film 12 To remain.

Thereafter, as shown in FIG. 10C, an interlayer insulating film 13 and a passivation film 14 are formed, and hydrogen sintering is performed. In order to suppress the metal bubble generation frequency and avoid the deterioration of the light shielding property, as shown in FIG. 13, the hydrogen sintering treatment is preferably performed at a hydrogen sintering temperature of 400 ° C. or higher and 450 ° C. or lower.

When the hydrogen sintering temperature is higher than 450 ° C., the light shielding performance of the light shielding portion 470 is deteriorated as compared with the case where the hydrogen sintering temperature is 450 ° C. or lower. On the other hand, when the hydrogen sintering temperature is less than 400 ° C., the device characteristics of the solid-state imaging device 400 are deteriorated due to white scratches and dark current. Accordingly, the hydrogen sintering temperature is preferably 400 ° C. or higher and 450 ° C. or lower. In the manufacture of the solid-state imaging device 400, the inventor of the present invention performed the hydrogen sintering process at a hydrogen sintering process temperature of 420 ° C. in consideration of the effect on device characteristics other than “avoidance of light shielding performance reduction”.

Thereafter, the color filter 15 is formed so as to have red, green, and blue spectral requirements, and the protective film 16 and the microlens 17 are formed to complete the solid-state imaging device 400.

Regarding the light-shielding portion 470 having a multilayer structure using an Al wiring layer used for the peripheral circuit, (1) the intervening film 11 immediately below the upper Al light-shielding film 12 is 5.0E8 Pa or more at which the film stress of the intervening film 11 is Tensile, (2) forming the upper Al light shielding film 12 by controlling the film thickness of the upper Al light shielding film 12 to be 50 nm or more and 125 nm or less; and (3) By performing the hydrogen sintering process at a hydrogen sintering temperature of 450 ° C. or less, it is possible to form a good light-shielding portion 470 in the OB pixel region B of the solid-state imaging device 400 without causing a light-shielding deterioration due to the generation of metal bubbles. .

[Appendix 1]
In the first to fourth embodiments, “the intervening film 11 and the upper Al film are aligned so that the direction of the film stress of the intervening film 11 and the direction of the film stress of the upper Al light shielding film 12 are both in the direction of extension (Tensile). The formation of the light shielding film 12 can suppress the generation of metal bubbles ”. However, if the difference between the thermal expansion coefficient (thermal expansion coefficient) of the intervening film 11 and the thermal expansion coefficient (thermal expansion coefficient) of the upper Al light shielding film 12 can be reduced, the direction of the film stress of the intervening film 11 extends ( The intervening film 11 and the upper Al light shielding film 12 may be formed so that the direction of the film stress of the upper Al light shielding film 12 is the compression (compressive) direction.

If the difference between the thermal expansion coefficient (thermal expansion coefficient) of the intervening film 11 and the thermal expansion coefficient (thermal expansion coefficient) of the upper Al light-shielding film 12 is small, the direction of the film stress of the intervening film 11 is extended (tensile, Even if the direction of the film stress of the upper Al light-shielding film 12 is the compression (compressive) direction, the stress on the upper Al light-shielding film 12 is reduced, and metal voids are less likely to occur. It is possible.

That is, if the difference between the thermal expansion coefficient (thermal expansion coefficient) of the intervening film 11 and the thermal expansion coefficient (thermal expansion coefficient) of the upper Al light shielding film 12 is reduced, the direction of the film stress of the intervening film 11 and the upper layer The direction of the film stress of the Al light shielding film 12 does not need to match.

[Appendix 2]
In the first to fourth embodiments, the case where the film thickness of the upper Al light shielding film (upper Al light shielding film 12) is 50 nm or more and 125 nm or less has been described. However, the film thickness of the lower Al light shielding film (third layer Al wiring 10, first layer Al wiring 108, second layer Al wiring 111, and lower Al light shielding film 115) is 50 nm or more, By setting the thickness to 125 nm or less, it is considered that vacancies existing in the lower Al light shielding film can be reduced, generation of metal voids in the lower Al light shielding film can be suppressed, and deterioration of the light shielding property can be avoided. . Further, for the same reason as described above for the film thickness of the upper Al light shielding film, it is more preferable that the film thickness of the lower Al light shielding film is 50 nm or more and 90 nm or less.

[Summary]
The solid-state imaging device (100, 200, 300, 400) according to the first aspect of the present invention has a light shielding portion (170, 270, 370, 470) that shields the optical black region (B) formed on the substrate (semiconductor substrate 120). ), Wherein the light-shielding portion is formed of a lower-layer light-shielding film (a third-layer aluminum wiring 10, a second-layer Al wiring 111, and a first-layer Al wiring in order from the side closer to the substrate). 108, a lower Al light shielding film 115), an intervening film (11), and an upper light shielding film (upper aluminum shielding film 12). The lower light shielding film and the upper light shielding film are made of aluminum or an aluminum alloy containing aluminum as a main component. The upper light-shielding film is formed with a thickness of 50 nm or more and 125 nm or less.

Here, it is considered that one cause of the metal voids generated in the upper light shielding film is a vacancy existing in the upper light shielding film. According to said structure, the said solid-state image sensor makes the film thickness of the said upper layer light shielding film thin, specifically, the film thickness of the upper layer aluminum light shielding film 12 shall be 50 nm or more and 125 nm or less. Thus, the vacancies existing in the upper light shielding film are reduced. Therefore, the solid-state imaging device can suppress the generation of metal voids in the upper light-shielding film and avoid a reduction in light-shielding performance.

In the solid-state imaging device, the thickness of the entire light-shielding portion can be suppressed by making the thickness of the upper light-shielding film thinner than the thickness of the intervening film.

Therefore, the solid-state imaging device can avoid a reduction in the light shielding property of the light shielding part while suppressing the thickness of the light shielding part that shields the optical black region.

In the solid-state imaging device according to aspect 2 of the present invention, in the above aspect 1, the interstitial film may have a tensile stress of 5.0E8 Pa or more and 7.0E8 Pa or less.

According to said structure, in the said solid-state image sensor, the tensile stress of the said interposition film is 5.0E8Pa or more and 7.0E8Pa or less, and the thermal expansion coefficient of the said interposition film and the said upper layer light shielding film is The difference is small.

Here, the inventor of the present application considered that the occurrence of the metal void is related to the film stress of the intervening film. Therefore, it was considered that the generation of the metal voids due to the stress caused by the film stress can be suppressed by reducing the difference in thermal expansion coefficient (thermal expansion coefficient) between the intervening film and the upper light shielding film. And this inventor confirmed that generation | occurrence | production of the said metal void can be suppressed by making tensile stress of the said intervening film into 5.0E8Pa or more and 7.0E8Pa or less. Therefore, the solid-state imaging device can suppress the generation of the metal voids.

In the method for manufacturing the solid-state imaging device (100, 200, 300, 400) according to the third aspect of the present invention, the light shielding portions (170, 270, 370, 470), wherein the light-shielding portion is formed of a lower-layer light-shielding film (third-layer aluminum wiring 10, second-layer Al wiring 111, in order from the side closer to the substrate). The first layer Al wiring 108, the lower layer Al light shielding film 115), the intervening film (11), the upper layer light shielding film (upper layer aluminum light shielding film 12), and the lower layer light shielding film is made of aluminum or an aluminum alloy mainly composed of aluminum. A lower-layer light-shielding film forming step of forming aluminum, and aluminum or an aluminum alloy containing aluminum as a main component, and having a film thickness of 50 nm or more, nm was controlled to become less including, an upper light shielding film formed step (S200) of forming the upper light shielding film.

According to the above manufacturing method, the same effects as those of the first aspect are obtained.

In the solid-state imaging device manufacturing method according to aspect 4 of the present invention, in the aspect 3, the interstitial film has a tensile stress of 5 after the lower light-shielding film forming step and before the upper light-shielding film forming step. An intervening film forming step (S100) for forming the intervening film by controlling the pressure to be 0E8Pa or higher and 7.0E8Pa or lower may be further included.

According to the above manufacturing method, the same effects as those of the second aspect are obtained.

The method for manufacturing a solid-state imaging device according to Aspect 5 of the present invention is the method of Aspect 3 or 4, wherein after the light shielding portion is formed, the hydrogen sintering process is performed at a hydrogen sintering temperature of 400 ° C. or higher and 450 ° C. or lower. A hydrogen sintering process execution step (S300) may be further included.

Here, the inventor of the present invention shows that when the hydrogen sintering temperature is higher than 450 ° C., the frequency of occurrence of metal bubbles (compared to the prior art) is higher than that when the hydrogen sintering temperature is 450 ° C. or lower. It was confirmed that the temperature rapidly increased as the sintering temperature increased. Further, the inventors of the present invention have confirmed that when the hydrogen sintering temperature is less than 400 ° C., the device characteristics of the solid-state imaging device are deteriorated due to white scratches and dark current.

Therefore, according to the above manufacturing method, it is possible to obtain the solid-state imaging device having good device characteristics while suppressing the frequency of occurrence of metal bubbles that cause a reduction in light shielding properties.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment.

The solid-state imaging device according to the present invention can be applied to various electronic devices such as camera-equipped mobile phones, digital video cameras, digital still cameras, security cameras (surveillance cameras), door phones, image input cameras, scanners, and facsimiles.

10 Third layer aluminum (Al) wiring (underlying light shielding film)
11 Intervening film 12 Upper layer aluminum (Al) light shielding film (upper layer light shielding film)
DESCRIPTION OF SYMBOLS 13 Interlayer insulation film 14 Passivation film 15 Color filter 16 Protective film 17 Micro lens 18 Resist 19 Resist 20 Conventional light-shielding part 20d Conventional lower-layer light-shielding film 20m Conventional intervening film 20u Conventional upper-layer light-shielding film 100 Solid-state imaging device DESCRIPTION OF SYMBOLS 101 Light-receiving part 102 Floating diffusion (FD) part 103 Element isolation part 104 Gate insulating film 104B Gate oxide film 105 Charge transfer electrode 106 Interlayer insulating film 107 Through-hole (contact)
108 First layer aluminum (Al) wiring (underlying light shielding film)
109 Interlayer insulating film 110 Through hole (via)
111 Second layer aluminum (Al) wiring (lower light shielding film)
112 Interlayer insulating film 113 Through hole (via)
114 Interlayer insulating film 114B Tungsten (W) light shielding film 115 Lower aluminum (Al) light shielding film (lower light shielding film)
120 Semiconductor substrate (substrate)
170 light-shielding part 200 solid-state image sensor 270 light-shielding part 300 solid-state image sensor 370 light-shielding part 400 solid-state image sensor 470 light-shielding part 1000 solid-state image sensor disclosed in Patent Document 1 A effective pixel area B OB pixel area C peripheral circuit area

Claims

A solid-state imaging device including a light-shielding portion that shields an optical black region formed on a substrate,
The light-shielding portion includes, in order from the side close to the substrate, a lower-layer light-shielding film, an intervening film, and an upper-layer light-shielding film,
The lower light-shielding film and the upper light-shielding film are formed of aluminum or an aluminum alloy containing aluminum as a main component,
A film thickness of the upper light-shielding film is 50 nm or more and 125 nm or less.
2. The solid-state imaging device according to claim 1, wherein the interstitial film has a tensile stress of 5.0E8 Pa or more and 7.0E8 Pa or less.
A method for manufacturing a solid-state imaging device including a light-shielding portion that shields an optical black region formed on a substrate,
The light-shielding portion includes, in order from the side close to the substrate, a lower-layer light-shielding film, an intervening film, and an upper-layer light-shielding film,
A lower light-shielding film forming step for forming the lower light-shielding film with aluminum or an aluminum alloy containing aluminum as a main component;
An upper light-shielding film forming step of forming the upper light-shielding film of aluminum or an aluminum alloy containing aluminum as a main component and having a film thickness of 50 nm or more and 125 nm or less. Production method.
After the lower light shielding film forming step, before the upper light shielding film forming step,
4. The method according to claim 3, further comprising an intervening film forming step of controlling the intervening film to have a tensile stress of 5.0E8 Pa or higher and 7.0 E8 Pa or lower to form the intervening film. Manufacturing method of the solid-state image sensor.
5. The solid according to claim 3, further comprising: a hydrogen sintering process performing step of performing a hydrogen sintering process at a hydrogen sintering temperature of 400 ° C. or more and 450 ° C. or less after forming the light shielding part. Manufacturing method of imaging device.