JPH04354161A - Solid-state image sensing element - Google Patents

Abstract

PURPOSE:To prevent the generation of a smear by preventing the light made obliquely incident on the opening of the aluminum light shielding film of a solid-state image sensing element from reaching adjacent picture elements. CONSTITUTION:After removing an interlayer oxide film 6 which is formed around an n-type semiconductor layer 3 for photoelectric conversion to the upper surfaces of polysilicon films 8 along the circumference of the opening section 7a of a light shielding film 7, tungsten peripheral walls 9 are formed by burying tungsten in the places from which the film 6 is removed by a selective tungsten CVD method.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention relates to a solid-state image sensor,
In particular, the present invention relates to a device designed to reduce false signals (smear) during photoelectric conversion.

0002

2. Description of the Related Art FIG. 2 is a cross-sectional view of a conventional solid-state image sensing device manufacturing process. In the figure, 1 is a P-type semiconductor substrate, 2 and 3 are an n-type semiconductor layer 2 for forming a buried channel and an n-type semiconductor layer 3 for photoelectric conversion, which are provided at predetermined locations on the surface of the substrate 1, and 4 is a buried channel forming layer. This is a thick P-type semiconductor layer for separating the n-type semiconductor layer 2 for photoelectric conversion and the n-type semiconductor layer 3 for photoelectric conversion. 5 is a polysilicon electrode for charge transfer provided through an insulating film 10, and is a polysilicon electrode for photoelectric conversion.
This is for transferring photocharges accumulated in the type semiconductor layer 3 to the channel forming n-type semiconductor layer 2. Reference numeral 6 denotes an interlayer oxide film between a first aluminum layer for wiring (not shown) connected to the polysilicon electrode 5 and a second aluminum layer 7 for shielding and wiring.

Next, the manufacturing method will be explained. First, Figure 2
As shown in (a), after implanting impurities into a predetermined region of a substrate 1 to form an n-type semiconductor layer 2 for forming a buried channel, an n-type semiconductor layer 3 for photoelectric conversion, and a P-type semiconductor layer 2, A polysilicon electrode 5 for charge transfer (first polysilicon electrode for charge transfer) is formed through an insulating film 10.

Next, unlike the polysilicon electrode 5 described above, a second polysilicon electrode (not shown) is provided for transferring the photocharges transferred to the n-type semiconductor layer 2 for channel formation in a direction perpendicular to the plane of the paper, and an insulating film is further provided. An interlayer oxide film 6 is provided through the interlayer oxide film 10, and a contact hole is provided in the interlayer oxide film 6.
The polysilicon electrode 5 and the first aluminum layer for wiring (not shown) are connected (FIG. 2(b)). Finally, a second aluminum layer 7 for light shielding and wiring is formed on the interlayer oxide film 6 so as to cover the area other than the photoelectric conversion section (FIG. 2(c)).

Next, the operation will be explained. Figure 2(c)
, the light incident from the opening 7a of the light shielding film 7 is n
The photoelectric charges are photoelectrically converted in the type semiconductor layer 3 and accumulated there as optical signal charges. Then, at a certain timing, this charge is transferred to the buried channel layer 2 using the first charge transfer polysilicon electrode 5, and then the first charge transfer polysilicon electrode 5 and the second charge transfer polysilicon electrode ( (not shown) in a direction perpendicular to the paper surface.

[0006]

[Problems to be Solved by the Invention] Since the conventional solid-state image sensing device is constructed as described above, the distance between the substrate surface on which the active region is formed and the light-shielding aluminum layer is wide, and as shown in FIG.
), there is a problem in which light incident from an angle reaches the adjacent pixel area or its transfer area, where it is photoelectrically converted or enters the transfer area, resulting in a false signal (smear). Ta.

The present invention was made in order to solve the above-mentioned problems, and it is a solid-state film that does not generate false signals in adjacent pixels even if light enters the opening of the light-shielding film obliquely. The purpose is to obtain an image sensor.

[0008]

[Means for Solving the Problems] A solid-state image sensing device according to the present invention is provided with a peripheral wall that reaches near the surface of a silicon substrate along the periphery of an opening in a light-shielding film.

[0009]

[Operation] In the present invention, a peripheral wall is formed along the periphery of the opening of the light shielding film so as to reach near the substrate surface, so that light incident obliquely to the opening is blocked by this peripheral wall, and the adjacent wall It never reaches the pixel.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a process cross-sectional view showing a method for manufacturing a solid-state image sensor according to an embodiment of the present invention. The same reference numerals as in FIG. 9 is a peripheral wall formed by selectively embedding tank stencil in the portion above this polysilicon film 8 from which interlayer oxide film 6 has been removed.

Next, the manufacturing method will be explained. 1(a) in the same manner as before, and then patterning is performed using the same polysilicon when forming a second layer of polysilicon electrode (not shown) to form a photoelectric conversion section as shown in FIG. 1(b). A polysilicon film 8 is provided so as to frame the periphery of the n-type semiconductor layer 3.

Next, an interlayer oxide film 6 is provided in the same manner as before.
After passing through the contact process and the first aluminum process for wiring, the interlayer oxide film 6 on the polysilicon film 8 is removed (FIG. 1(c)).
).

Then, by selective tungsten CVD, the part where the oxide film 6 was removed in FIG. 1(c) is filled,
A peripheral wall 9 surrounding the n-type semiconductor layer 3 is formed (see FIG. 1(
d)). Finally, as in the conventional method, a second aluminum layer 7 for light shielding and wiring is provided in the region excluding the upper part of the n-type semiconductor layer 3 (FIG. 1(e)).

As described above, according to this embodiment, since the peripheral wall 9 surrounding the n-type semiconductor layer 3, which is the photoelectric conversion section, is provided, even if light enters the opening 7a of the light-shielding film 7 in an oblique direction, It is blocked by this peripheral wall 9 and does not invade the active region of an adjacent pixel portion, so that smear does not occur.

Furthermore, although oxide films and tungsten generally do not have good adhesion, in this embodiment, the polysilicon film 8 is provided around the n-type semiconductor layer 3 and then the tungsten is embedded, so that it is easy to can be embedded with tungsten. Furthermore, since this polysilicon film 8 is obtained by patterning simultaneously when forming the second layer polysilicon electrode (not shown), the number of manufacturing steps does not increase.

Although the peripheral wall was formed using tungsten in the above embodiment, it goes without saying that the material used is not limited to this. Furthermore, if the peripheral wall can be formed using a material that has good adhesion to the insulating film and has a high light shielding ability, it is not necessary to provide the polysilicon film 8.

[0017]

As described above, according to the solid-state image pickup device of the present invention, since the peripheral wall is provided along the periphery of the opening of the light-shielding film so as to reach near the substrate surface, light enters the opening obliquely. Even if it is incident, it is blocked by this peripheral wall, and there is an effect that it is possible to obtain a solid-state image sensor in which smear does not occur in adjacent pixels.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a method for manufacturing a solid-state image sensor according to an embodiment of the present invention.

FIG. 2 is a diagram showing a conventional method for manufacturing a solid-state image sensor.

[Explanation of symbols]

1 P-type semiconductor substrate 2 N-type semiconductor layer for buried channel formation (CCD)
3 N-type semiconductor layer for photoelectric conversion (photoelectric conversion section) 4 Dark P-type semiconductor layer 5 Polysilicon electrode for charge transfer 6 Interlayer oxide film 7 Second aluminum layer for light shielding and wiring 8 Polysilicon film 9 Peripheral wall

Claims (2)

[Claims] 1. A plurality of photoelectric conversion layers formed for each pixel on the surface of a semiconductor substrate, a buried channel layer for transferring photoelectrically converted charges, a transfer electrode formed on the buried channel layer, and a plurality of photoelectric conversion layers formed for each pixel on the surface of a semiconductor substrate. In the solid-state imaging device, the solid-state imaging device includes a light-shielding film provided through an interlayer film to cover a region other than the photoelectric conversion section, in which the photoelectric conversion section is provided in the interlayer film region extending from above the photoelectric conversion section to the light-shielding film. What is claimed is: 1. A solid-state imaging device comprising: a peripheral wall formed to surround a solid-state image sensor. 2. The solid-state image pickup device according to claim 1, wherein the peripheral wall is formed via a base member provided at the periphery of the photoelectric conversion section.