JPH06310701A - Solid state image pickup element - Google Patents

Abstract

PURPOSE:To provide a CCD solid state image pickup element in which smear due to the light component entering between the Al light shield film and semiconductor region is reduced. CONSTITUTION:The solid state image pickup element comprises a vertical transfer register 5 arranged on the CCD solid state imaging element side at a light receiving part 10, and an Al light shield film 18 covering the vertical transfer register 5, wherein a dielectric film 12 underlying the part 18a of the Al light shield film stretching to the side of the light receiving part 10 is colored.

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 for reducing smear.

[0002]

2. Description of the Related Art FIG. 6 shows an example of a conventional CCD solid-state image pickup device. This CCD solid-state imaging device 1 has a first conductivity type, for example, an N-type silicon substrate 2, and a first second conductivity type, that is, P.
An N-type impurity diffusion region 4, an N-type transfer channel region 6 and a P-type channel stop region 7 forming a vertical transfer register 5 are formed in the N-type well diffusion region 3, and on the N-type impurity diffusion region 4. The P-type positive charge storage region 8 is
The second P-type well regions 9 are formed immediately below the transfer channels 6 of the respective shapes.

Here, a photodiode PD is formed by the PN junction j of the N type impurity diffusion region 4 and the P type well region 3.
The light receiving unit (photoelectric conversion unit) 10 is configured by. The light receiving unit 10 is formed corresponding to each pixel.

Then, S is formed on the transfer channel region 6, the channel stop region 7 and the read gate portion 11 which will be described later, which constitute the vertical transfer register 5, via the SiO ₂ film 12.
The iN film 13 is laminated. This SiO ₂ film 12 and Si
A transfer electrode 16 made of polycrystalline silicon is formed on the gate insulating film 15 having a two-layer structure of the N film 13, and the transfer channel region 6, the gate insulating film 15 and the transfer electrode 16 form C
A vertical transfer register 5 having a CD structure is configured.

An SiO ₂ film 14 is formed on the surface of the transfer electrode 16, and an interlayer insulating film 17 made of PSG (phosphorus silicate glass) is formed on the entire surface including the transfer electrode 16 and the positive charge storage region 8 of the light receiving portion. Are laminated, and an Al light-shielding film 18 is selectively formed on the transfer electrode 16 via the interlayer insulating film 17.

The Al light-shielding film 18 has a protruding portion that partially extends toward the light-receiving portion 10 in order to block light that is directly incident on the vertical transfer register 5 from the light-receiving portion 10 (light that is obliquely incident). 18a is integrally provided. And this Al
For example, a plasma SiN film 19 is formed on the entire surface including the light shielding film 18.
And the planarization film 20 is sequentially formed. This flattening film 20
The color filter layer 21 is formed thereon, and the on-chip microlens 22 is further formed on the color filter layer 21 at a position corresponding to the light receiving portion 10.

The transfer electrode 16 is formed so as to extend between the vertical transfer register 5 and the light receiving portion 10, and the read gate portion 11 is formed here.

[0008]

In recent years, miniaturization of solid-state image pickup devices has been promoted. Along with this miniaturization, even if the curvature of the on-chip microlens 22 or the film thickness of the flattening film 20 or the like is adjusted, it is impossible to make a focus on the light receiving unit 10.

Therefore, since the light L that has passed through the on-chip microlens 22 is not completely condensed, a part of the light component L ₁
However, light leakage into the so-called vertical transfer register 5, which causes repeated reflection between the protruding portion 18a of the Al light-shielding film 18 and the silicon region to directly enter the vertical transfer register 5, increases smear. It is the main cause.

In view of the above points, the present invention provides a solid-state image sensor capable of reducing smear.

[0011]

The present invention provides a solid-state image pickup device in which a vertical transfer register 5 is arranged on one side of a light receiving portion 10 and a light-shielding film 18 is formed so as to cover the vertical transfer register 5. The insulating film 12 (or 17 and 12) under the protruding portion 18a protruding toward the light receiving portion 10 side of the film 18 is colored and configured.

[0012]

In the present invention, the insulating film 12 (or 1) below the protruding portion 18a protruding toward the light receiving portion 10 side of the light shielding film 18 is provided.
7 and 12) are colored, the multiple reflection caused between the protrusion portion and the semiconductor region by the light component L ₁ incident below the protrusion portion 18a of the light shielding film 18 is attenuated, and the light to the vertical transfer register 5 is attenuated. Leakage is reduced and smear is reduced.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a CCD solid-state image pickup device according to the present invention. In the CCD solid-state imaging device 30 of this example, an N-type impurity diffusion region 4 and a N-type impurity diffusion region 4 are vertically formed in a well region 3 of a first conductivity type, that is, an N-type silicon substrate 2, that is, a P-type. An N-type transfer channel region 6 and a P-type channel stop region 7 which form the transfer register 5 are formed, and a P-type positive charge storage region 8 and an N-type transfer channel are formed on the N-type impurity diffusion region 4. The second P-type well regions 9 are formed immediately below the regions 6, respectively.

Here, the photodiode PD is formed by the PN junction j of the N type impurity diffusion region 4 and the P type well region 3.
The light receiving unit (photoelectric conversion unit) 10 is configured by. The light receiving unit 10 is formed corresponding to each pixel.

Then, the SiN film 1 is formed on the transfer channel region 6, the channel stop region 7 and the read gate portion 11 which constitute the vertical transfer register 5 via the SiO ₂ film 12.
3 are stacked. This SiO ₂ film 12 and SiN film 13
A transfer electrode 16 made of polycrystalline silicon is formed on the gate insulating film 15 having a two-layer structure, and the transfer channel region 6, the gate insulating film 15 and the transfer electrode 16 form a vertical transfer register 5 having a CCD structure.

An SiO ₂ film 14 is formed on the surface of the transfer electrode 16, and an interlayer insulating film 17 made of PSG (phosphorus silicate glass) is formed on the entire surface including the transfer electrode 16 and the positive charge storage region 8 of the light receiving portion. Are laminated, and an Al light-shielding film 18 is selectively formed on the transfer electrode 16 via the interlayer insulating film 17.

The Al light-shielding film 18 has a protruding portion 18a partially extending toward the light-receiving portion 10 in order to block light (light obliquely incident) directly incident on the vertical transfer register 5 from the light-receiving portion 10. Are provided integrally.

For example, a plasma SiN film 19 and a flattening film 20 are sequentially formed on the entire surface including the Al light-shielding film 18, a color filter layer 21 is formed on the flattening film 20, and further on the color filter layer 21. An on-chip microlens 22 for condensing incident light on the light receiving unit 10 is formed at a position corresponding to the light receiving unit 10.

In this example, the Al light shielding portion 18 is particularly
For example, the insulating film of the portion located below the protruding portion 18a
SiO₂The film 12 has a color of low reflection and high absorptivity (for example, black,
Other colors, etc.) 23 is this insulation
The colored area of the membrane is shown. SiO ₂The color of the film 12 is, for example,
It is made by ion implantation of carbon.

A low reflection film 24 is formed under the Al light-shielding film 18, at least under the protruding portion 18a. As the low reflection film 24, for example, TiON film, TiN
It can be formed of a film or the like.

2 and 3 show an example of a manufacturing method for forming the colored region 23 of the SiO ₂ film 12. First, FIG.
As shown in A, a SiO ₂ film 12 is formed on the entire surface of the first P-type well region 3 in which the transfer channel region 6, the second P-type well region 9 and the channel stop region 7 are formed. _{2 A} SiN film 13 and a transfer electrode 16 made of polycrystalline silicon are selectively formed on a part of the film 12 (that is, a part excluding the light receiving portion 10). Next, Al formed later
On the SiO ₂ film 12 corresponding to the light receiving portion 10 and the transfer electrode 1 except the portion corresponding to the protruding portion 18 a of the light shielding portion 18.
A photoresist mask 26 is selectively formed on the surface 8.

Next, as shown in FIG. 2B, the Al light-shielding film 18 of the SiO ₂ film 12 is interposed through the photoresist mask 26.
A colorant, for example, carbon 27 is ion-implanted into a portion corresponding to the underside of the protruding portion 18a.

Next, by removing the photoresist mask 26, as shown in FIG. 3C, a colored region 23 colored black with carbon is selectively formed at a desired position of the SiO ₂ film 12.

Next, as shown in FIG. 3D, an N-type impurity diffusion region 4 and a P-type positive charge accumulation region 8 are ion-implanted in a region of the first P-type well region 3 corresponding to the light receiving portion 10. Form. Next, after the SiO ₂ film 14 is formed on the surface of the transfer electrode 16, the PSG interlayer insulating film 17 is formed, and then the Al light shielding film 18 is formed. Thereafter, although not shown, the plasma SiN film 19, the flattening film 20, the color filter layer 21, and the on-chip microlens 22 are formed.

It should be noted that N-type impurities forming the light receiving portion 10
For forming the diffusion region 4 and the P-type positive charge accumulation region 8
Ion implantation process and car for forming colored region 23
The order of the ion implantation process of Bonn can be either first.
Is. In the above example, SiO₂Film 12 and SiN film 1
Although the gate insulating film 15 was formed in the two-layer structure of No. 3,
Other, SiO₂The film 12, the SiN film 13 and the Si thereon
O ₂It is also possible to construct the gate insulating film with a three-layer structure of film.
It

According to this embodiment described above, the Al light-shielding film 1 is formed.
The SiO ₂ film 12 under the protruding portion 18a of No. 8 is colored with carbon, and the colored region 23 of low reflection and high absorptivity
By forming
The light component L _{1 that} is multiply reflected between the Al protrusion 18 a and the silicon region 8 is attenuated in the colored region 23. In addition, the light component L _{1 which} is multiply reflected is the protrusion 1 of the Al light-shielding film 18.
It is also attenuated by the low reflection film 24 formed on the lower surface of 8a.

As a result, leakage of light into the vertical transfer register 5 is reduced, and smear caused by multiple reflection between the Al protrusion 18a and the silicon region 8 can be reduced.

Although the entire thickness of the SiO ₂ film 12 is colored in the above example, only the surface of the SiO ₂ film 12 may be colored.

FIG. 4 shows another embodiment. In this example, all of the insulating film below the protruding portion 18a of the Al light-shielding film 18, that is, P
The interlayer insulating film 17 made of SG and the SiO ₂ film 1 thereunder
Both 2 are colored with a color of low reflection and high absorptivity (for example, black or other color) to form the colored region 23. With this configuration, the effect of attenuating the multiple reflection between the protrusion 18a and the silicon region is further enhanced, and smear can be further reduced.

FIG. 5 shows still another embodiment. In this example, A
l With respect to the insulating film below the protruding portion 18a of the light-shielding film 18,
The interlayer insulating film 17 is included in FIG. 5 up to the middle of the film thickness direction, and the colored region 23 is formed up to the middle of the SiO ₂ film 12 thereunder by coloring with a color of low reflection and high absorptivity. With this configuration, the occurrence of smear can be reduced and the colored area 23
Does not contact the silicon region 8, the silicon region 8 is not affected by the colored region 23.

The CCD solid-state image pickup device according to the present invention described above can be applied to a CCD solid-state image pickup device of a frame interline transfer system, an interline transfer system or the like.

[0033]

According to the present invention, by coloring the insulating film below the protruding portion protruding to the light receiving portion side of the light shielding film covering the vertical transfer register, the light is incident below the light shielding film through the opening of the light receiving portion. Multiple reflection of the generated light component can be attenuated, and smear due to the light component incident between the light-shielding film and the semiconductor region can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a CCD solid-state image sensor according to the present invention.

FIG. 2 is a manufacturing process diagram (1) showing an example of a method for manufacturing a CCD solid-state imaging device according to the present invention.

FIG. 3 is a manufacturing process diagram (2) showing an example of a method of manufacturing the CCD solid-state imaging device according to the present invention.

FIG. 4 is a cross-sectional view of a main part showing another example of the CCD solid-state imaging device according to the present invention.

FIG. 5 is a sectional view of an essential part showing still another example of the CCD solid-state imaging device according to the present invention.

FIG. 6 is a sectional view showing an example of a conventional CCD solid-state imaging device.

[Explanation of symbols]

1,30 CCD solid-state image sensor 2 N-type silicon substrate 3 First P-type well region 4 N-type impurity diffusion region 5 Vertical transfer register 6 Transfer channel region 7 Channel stop region 8 Positive charge storage region 9 Second P-type well Region 10 Light receiving portion 11 Reading portion 12 SiO ₂ film 13 SiN film 14 SiO ₂ film 15 Gate insulating film 16 Transfer electrode 17 Interlayer insulating film 18 Al light shielding film 18a Overhanging portion 19 Plasma SiN film 20 Flattening film 21 Color filter layer 22 On-chip micro lens 23 Colored area 24 Low reflection film 26 Photoresist mask 27 Carbon

Claims (1)

[Claims] 1. A solid-state imaging device comprising a vertical transfer register disposed on one side of a light-receiving portion, and a light-shielding film formed on the vertical transfer register so as to extend to the light-receiving portion side of the light-shielding film. A solid-state image pickup device, characterized in that an insulating film below the protruding portion is colored.