JPH05226621A - Solid-state image pick-up element and its manufacture - Google Patents

Abstract

PURPOSE:To achieve a solid-stage image pick-up element without any detection of a solid pattern by performing patterning so that a plurality of layers may remain as an annular wall which separates a light-reception part from a peripheral circuit part and then forming a frame body part around a picture-element part. CONSTITUTION:Polysilicon is laminated on a silicon substrate 1 through an insulation interlayer film 3, a resist is coated, and exposure and patterning are made for eliminating etching and obtaining an electrode pattern 4 but a pattern surrounding a periphery of a picture-element part 31 is left at the time of exposure, and a frame-shaped pattern according to the polysilicon layer 4 is formed in reference to pads 32. Also, patterning is made similarly when forming a second polysilicon electrode layer 6 and an alumina layer 8 for screening light and wiring for leaving a frame-shaped pattern so that the picture-element part 31 may be surrounded, thus forming the frame-body part 1. Then, when a resist for patterning a light-screening film and the alumina 8 for wiring is rotated and coated, it spreads from the center part of a wafer toward outside and then a film thickness of the resist within the picture-element part 31 is regulated by the frame body part 1, thus achieving a light-screening pattern for reducing coating nonuniformity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a solid-state image pickup device and a method of manufacturing the same, and more particularly to a method and a structure for improving processing accuracy when forming a light shielding film.

[0002]

2. Description of the Related Art FIG. 3 is an overall view of a chip showing a conventional solid-state image pickup device. In the figure, 31 is a pixel portion for performing photoelectric conversion, in which a plurality of light receiving elements are arranged in a matrix and a light receiving area is formed. Each is divided by a light shielding film having an opening. 32 is a pad section for exchanging signals with the outside of the chip, 33 is a pad section 32 and a pixel section 31.
A wiring bridging portion for connecting to a CCD electrode (not shown) inside, a dicing line portion 34 for cutting out each chip from the wafer, and a resist coating unevenness caused when forming a light shielding film (not shown). Shows the line. See also FIG.
3 is a cross-sectional view taken along the line AA ′ of FIG.
An interlayer insulating film 3, a first electrode polysilicon layer 4, an interlayer insulating film 5, a second electrode polysilicon layer 6, an interlayer insulating film 7, a light-shielding and wiring aluminum 8 are sequentially formed thereon.

Next, a manufacturing method, especially a light-shielding film forming step will be described. Before the light-shielding film forming step, as shown in FIG. 3, the first electrode polysilicon layer 4 forming the pad portion 32 is formed.
And a bridging electrode (an electrode that straddles the wiring) 33, a second electrode polysilicon layer 6 serving as a CCD electrode in the pixel portion 31, and a dicing line 34 are formed. There are irregularities.

FIG. 5 shows a schematic flow of the light-shielding film forming process. First, a light shielding film material 52 such as Al is laminated by a sputtering method or the like on the substrate 51 which has been processed up to the step of forming the light shielding film, and then a resist 53 is applied by a spin coating method (FIG. 5 (a)). ).

Next, exposure and development are performed using a desired mask to form a resist pattern 53a (FIG. 5 (b)).

After that, the light shielding film material 52 is etched by using the resist pattern 53a as a mask, and a desired Al is formed.
A pattern 52a is obtained (FIG. 5 (c)).

Finally, the resist is removed to form an Al pattern 52a which shields a desired portion of the substrate 51 from light (FIG. 5 (d)).
).

[0008]

In the conventional method for manufacturing a solid-state image pickup device, the light-shielding film is patterned by the above-mentioned process. However, the light-shielding film material is formed on the uneven surface of the base and spin coating is performed. Since the resist pattern is formed by the method, uneven coating occurs during resist spin coating, as indicated by the broken line in FIG. 3, and uneven film thickness occurs. Since the unevenness of the film thickness is reflected on the unevenness of the size of the resist pattern, there is a problem in that the unevenness of the opening of the light-shielding pattern in the pixel portion is detected, and the unevenness of the opening in the pixel portion is detected as a fixed pattern during imaging.

In order to solve the above problems, for example, as shown in Japanese Patent Laid-Open No. 62-145770, a separation portion higher than the pixel portion and the peripheral circuit portion is formed so as to surround the pixel portion. However, there is a method in which resist unevenness is reduced by spin-coating the resist in this state, but in this case, a new manufacturing flow for creating the separation part must be added, and the manufacturing process Was caused to increase.

The present invention has been made to solve the above-mentioned problems, and reduces coating unevenness in the pixel portion without increasing the number of manufacturing steps, and fixes the light-shielding pattern at the time of image pickup by the unevenness of the opening. An object of the present invention is to provide a method and a structure for manufacturing a solid-state image sensor without detecting a pattern.

[0011]

In a fixed image pickup device and a method of manufacturing the same according to the present invention, when patterning a plurality of layers for forming a device on a substrate, the plurality of layers form a light receiving portion and a peripheral portion. This is performed so as to remain as an annular wall that separates from the circuit portion, and a frame body portion is formed around the pixel portion.

When the light receiving section and the peripheral circuit section are electrically connected by a wiring layer beyond the frame section,
At the intersection of the frame and the wiring layer, the wiring layer is provided with an overhanging portion parallel to the frame for maintaining the width of the frame.

Further, the semiconductor layer structure forming the frame portion is formed such that the width becomes smaller toward the upper portion thereof.

[0014]

According to the present invention, when patterning a plurality of layers for forming elements on the substrate, the plurality of layers are left as annular walls separating the light receiving portion and the peripheral circuit portion. Since the frame is formed around the pixel portion, it is possible to reduce coating unevenness during resist spin coating without increasing the number of manufacturing steps.

At the intersection of the frame and the wiring layer, an overhanging portion parallel to the frame is provided in the wiring layer to maintain the width of the frame. Even if the light receiving portion and the peripheral circuit portion are electrically connected to each other by the wiring layer, uneven coating of the resist does not occur.

Further, since the semiconductor layer structure forming the frame portion is formed so that the width becomes smaller toward the upper portion thereof, the flow of the resist during spin coating becomes smooth.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A solid-state image sensor according to an embodiment of the present invention will be described below with reference to the drawings. 1, the same reference numerals as those in FIG. 3 indicate the same or corresponding portions, FIG. 1 (a) is an overall view of the chip, and FIG. 1 (b) is a cross section taken along the line AA ′ of FIG. 1 (a). 1 is a frame portion formed around the pixel portion 31, 2 is a Si substrate on which the pixel portion 31 and the like are formed, 3, 5 and 7 are insulating interlayer films, and 4 is a frame body. A first electrode polysilicon formed at a portion corresponding to the portion 1, 6 is a second electrode polysilicon formed above the first electrode polysilicon 4 via an insulating interlayer film 5, 8 Indicates light shielding and wiring aluminum.

Next, the manufacturing method will be described. In a solid-state imaging device composed of two layers of polysilicon for electrodes and one layer of light-shielding and wiring aluminum, for example, when the first electrode polysilicon 4 is formed, the same polysilicon as the conventional light-shielding film formation flow is used. Are laminated on the silicon substrate 1 via the insulating interlayer film 3 by a sputtering method or the like, a resist is subsequently applied, the resist is patterned by exposure and development, and then the polysilicon is etched to remove the desired resist. The electrode pattern 4 is obtained.

At the time of exposing the resist, at the same time, the resist is exposed so as to leave a pattern surrounding the periphery of the pixel portion 31, and a frame-shaped pattern of the first polysilicon layer 4 is formed between the pixel portion 31 and the pad portion 32. .. Similarly, except for the film to be removed over the entire surface, patterning is similarly performed when the second polysilicon electrode layer 6, the light shielding and wiring aluminum layer 8 is formed, and a frame-shaped pattern surrounding the pixel portion 31 is left. The frame body portion 1 is formed.

In this state, when a resist for patterning the light-shielding film and the aluminum 8 for wiring is spin-coated, the resist spreads from the central portion of the wafer to the outside by centrifugal force, and for example, the pixel portion 31 of FIG. To pad 32
Toward the peripheral portion where the pad portion 32 is formed (the direction of the line A′-A), the frame portion 1 is passed over, and the pixel portion 31 flows to the peripheral circuit portion where the pad portion 32 is formed. The thickness is regulated by the frame body portion 1. Therefore, in the pixel portion 31, the coating thickness is uniform without causing coating unevenness due to the steps of the pad portion 32, the wiring bridging portion 33, and the like, and the light shielding pattern as designed can be obtained.

As described above, according to this embodiment, when patterning layers to be laminated such as a semiconductor layer, an insulating layer, and a wiring layer in a process of manufacturing pixels and wirings of a solid-state image pickup device, these are pixel Since the frame portion 1 is formed so as to surround the portion 31, the coating unevenness in the pixel portion 31 at the time of resist rotation coating can be reduced without increasing the number of manufacturing steps, and as designed. A light-shielding pattern having an opening can be obtained.

In forming the frame body 1, the second
The electrode polysilicon 6 is replaced with the first electrode polysilicon 4
Since the patterning is performed so that the width is smaller than that of the frame body 1, the side surface of the frame body portion 1 is formed in a stepped shape, the flow of the resist during the spin coating becomes smooth, and the effect of reducing coating unevenness is enhanced. ing.

By the way, when the pixel portion 31 and the peripheral circuit portion are connected, the frame body portion 1 and the wiring layer intersect with each other. In this case, as shown in FIG. A part of the aluminum 8 constituting 1 may be patterned and removed to form the aluminum 8a intersecting the frame portion 1. In this case, the unevenness of the wiring layers 8 and 8a may cause uneven coating. The distance between the aluminum 8 and 8a is preferably about 50 μm or less so as not to occur.

Further, as shown in FIG. 2 (b), the aluminum 8b intersecting with the frame body 1 is formed with a projecting portion 80 parallel to the aluminum 8 constituting the frame body 1 so that the width of the aluminum 8 can be reduced. By securing it, the frame body part 1 by the space between the aluminum 8 and 8b
It is also possible to reduce the unevenness.

In the above embodiment, the Si of the solid-state image pickup device is
Although the case of reducing the coating unevenness of the resist during the process is shown, it can be similarly applied to the flow of forming the on-chip color filter, the on-chip microlens and the like in the subsequent steps, and the same effect as the above-described embodiment is obtained. ..

Further, in the above-mentioned embodiment, one frame body portion around the pixel portion is formed, but the frame body portion may be double or triplet, and the same effect as that of the above-mentioned embodiment is obtained. Play.

[0027]

As described above, according to the present invention, when patterning a plurality of layers for forming elements on a substrate, the plurality of layers separate the light receiving portion and the peripheral circuit portion. Since the frame is formed so as to remain as an annular wall around the pixel portion, uneven coating during resist spin coating can be reduced without increasing the manufacturing process, and fixing during imaging The effect is that the pattern can be eliminated.

Further, at the intersection of the frame and the wiring layer, the wiring layer is provided with a protrusion parallel to the frame so that the width of the frame is maintained. There is an effect that the light receiving portion and the peripheral circuit portion can be electrically connected to each other by the wiring layer over the frame body without inviting.

Further, since the semiconductor layer structure forming the frame portion is formed so that the width becomes smaller toward the upper portion thereof, the flow of the resist during spin coating becomes smooth,
There is an effect that the effect of reducing coating unevenness can be enhanced.

[Brief description of drawings]

FIG. 1 is a plan view and a partial sectional view of a chip of a solid-state image sensor according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a part of a frame body portion of a solid-state image sensor according to an embodiment of the present invention.

FIG. 3 is a plan view of a chip of a conventional solid-state image sensor.

FIG. 4 is a partial cross-sectional view of a conventional solid-state image sensor.

FIG. 5 is a cross-sectional view showing a manufacturing process of a light-shielding film and a wiring layer of a conventional solid-state imaging device.

[Explanation of symbols]

 1 Frame around pixel part 8 Light-shielding and wiring aluminum 8a Wiring aluminum 8b Wiring aluminum 80 Overhang part 31 Pixel part 32 Pad part 33 Bridging electrode part

Claims (4)

[Claims] 1. A solid-state imaging device comprising: a light receiving section; a peripheral circuit section for processing a signal from the light receiving section; and a frame section provided between the light receiving section and the peripheral circuit section. A solid-state imaging device, wherein the frame body portion is formed by using a semiconductor layer structure forming the light receiving portion and the peripheral circuit portion. 2. The solid-state image pickup device according to claim 1, wherein a part of a semiconductor layer structure forming the frame body includes a wiring layer electrically connecting the light receiving part and a peripheral circuit part, At the intersection between the body and the wiring layer, the width of the frame body portion is reduced, and the wiring layer is parallel to the frame body portion for maintaining the width of the frame body portion at the intersection portion. A solid-state image sensor having an overhang portion. 3. The solid-state image pickup device according to claim 1, wherein the semiconductor layer structure forming the frame body portion is formed so that the width becomes smaller toward the upper part thereof. 4. A method for manufacturing a solid-state imaging device by forming and patterning a plurality of layers for forming an element on a substrate to form a light receiving part and a peripheral circuit part, wherein a plurality of the device forming elements are formed. The method for manufacturing a solid-state imaging device, wherein the patterning of the layers is performed such that the plurality of layers remain as an annular wall that separates the light receiving unit and the peripheral circuit unit.