JP2687508B2 - Solid-state imaging device - Google Patents

Description

The present invention relates to a one-dimensional and two-dimensional solid-state image pickup device, and more particularly to a device with uniform sensitivity.

[Conventional technology]

Conventionally, in a solid-state imaging device, an aluminum thin film forming a signal wiring and an aluminum thin film forming a light shielding film that defines a light receiving area are formed in the same process. For this reason, the aluminum thin films have the same grain size (grain size), and the grain size is relatively large (about 3.0 μm or more) in order to prevent electromigration in the signal wiring through which a large current flows.

[Problems to be solved by the invention]

In the above-described conventional solid-state imaging device, since the grain size of the aluminum thin film of the light shielding film is the same as the grain size of the aluminum thin film of the signal wiring, the following problems occur.

That is, in the solid-state imaging device, as shown in FIG. 3 showing a part of the plan view of the light receiving element region, after forming the light shielding film 5 ′ so as to define the light receiving elements 8 and the channel cut regions 9 which are alternately arranged, It is annealed at 400-450 ℃. At this time, the aluminum causes thermal transfer due to the annealing temperature, and as shown by the slanted lines in the figure, a phenomenon occurs in which the particles 5b jump out along the boundary toward the light receiving element.

Therefore, the protruding particles 5b cause the light receiving area of the light receiving element 8 in this portion to be smaller than the light receiving areas of the other light receiving elements, and the sensitivity of the light receiving element in this portion is lowered.

It is an object of the present invention to provide a solid-state imaging device that prevents such a decrease in sensitivity.

[Means for solving the problem]

In the solid-state imaging device of the present invention, the aluminum particles of the aluminum thin film forming the light-shielding film that defines the light-receiving area of the light-receiving element are formed to have a smaller particle size than the aluminum particles of the aluminum thin film formed as the signal wiring in the solid-state imaging device. doing.

[Action]

In the above-described configuration, the aluminum grain size of the aluminum thin film in the signal wiring is increased to secure the electromigration resistance, while the reduction of the area of the light receiving element due to the protrusion phenomenon of the aluminum grains on the light shielding plate is suppressed.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

1 (a) and 1 (b) are sectional views showing an embodiment of the present invention in the order of manufacturing steps, and FIG. 2 is a plan view thereof.

That is, as shown in FIG. 1A, an N-type diffusion layer 2 is formed on one main surface of a P-type silicon substrate 1, and a readout electrode 3 made of polycrystalline silicon is formed via an oxide film. After that, an interlayer film 4 is formed, an aluminum thin film is deposited on this, and this is patterned to form a light-shielding film 5. At this time, the aluminum thin film is formed so that the grain size is about 1.0 μm or less. The film thickness is about 0.5 μm.

Next, as shown in FIG. 1B, annealing is performed in the range of about 400 to 450 ° C. to deposit the interlayer film 6 made of a silicon oxide film by the CVD method. The film thickness is about 0.5 μm.

Then, a contact hole (not shown) is formed in the interlayer film, and an aluminum thin film is formed in a desired pattern on the contact hole to form the signal wiring 7. This signal wiring 7 is approximately
Formed with a large grain size of 3.0 μm or more to obtain electromigration resistance.

In the solid-state imaging device manufactured in this manner, the aluminum grain size of the light shielding film 5 is extremely smaller than the aluminum grain size of the signal wiring 7. For this reason, even if a particle pop-out phenomenon occurs due to annealing after the formation of the light-shielding film, the particle pops out into the light-receiving element portion in which the light-receiving elements 8 and the channel cut regions 9 are alternately arranged as shown by the hatched lines in FIG. 5a is extremely small and has almost no effect on the light receiving area of the light receiving element 8. Therefore, the sensitivity of the light receiving element in this portion is not lowered as compared with the other light receiving elements, and a high-sensitivity solid-state imaging device can be configured.

〔The invention's effect〕

As described above, according to the present invention, the aluminum particles of the aluminum thin film forming the light-shielding film have a smaller particle diameter than the particles of the aluminum thin film forming the signal wiring. Thus, the resistance to electromigration is secured, while the reduction of the area of the light receiving element due to the phenomenon of aluminum particles protruding on the light shielding plate is suppressed, and the light receiving sensitivity and the uniformity thereof can be improved.

[Brief description of the drawings]

1 (a) and 1 (b) are cross-sectional views showing an example of a method of manufacturing a solid-state imaging device according to the present invention in the order of manufacturing steps, FIG. 2 is a plan view of a main portion of an embodiment of the present invention, and FIG. It is a top view of a part of conventional solid-state imaging device. 1 ... P-type silicon substrate, 2 ... N-type diffusion layer, 3 ... readout electrode, 4 ... interlayer film, 5,5 '... light-shielding film, 5a, 5b ...
Aluminum particles, 6 ... Interlayer film, 7 ... Signal wiring, 8
...... Light receiving element, 9 ...... Channel cut area.

Claims (1)

(57) [Claims] 1. In a solid-state imaging device comprising a light receiving element arranged on a semiconductor substrate, and the light receiving area of the light receiving element is defined by a light shielding film made of an aluminum thin film, aluminum particles of the aluminum thin film forming the light shielding film are A solid-state imaging device having a particle size smaller than that of aluminum particles of an aluminum thin film formed as signal wiring in the solid-state imaging device.