JPS6212154A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To improve the sensitivity of a solid-state image pickup element by providing a means introducing incident beams to a photosensitive section. CONSTITUTION:A concave lens 9 is fitted onto a light-shielding section 6 as a means introducing incident beams to a photosensitive section. Beams 1 projected onto the light-shielding section 6 are condensed to the photosensitive section 7 by the concave lens 9, and can be utilized effectively. The dispersion of sensitivity due to the change of the shapes of the lenses by contacts between the lenses 2 on the light-shielding sections 6 is not generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a solid-state imaging device, and particularly to a solid-state imaging device suitable for effectively utilizing light incident on a non-photosensitive portion.

[Background of the invention]

In order to effectively utilize incident light in a solid-state imaging device, conventionally, Japanese Patent Application Laid-Open No. 55-138979 and Japanese Patent Application Laid-open No. 59-004 have been proposed.
As described in No. 67, it has been considered to provide a non-focus condenser array or a convex condenser lens corresponding to each pixel. Figures 1 (a) and (b) show the prior art. Figure 1 (a) shows that the incident light 1 is condensed onto the photosensitive section 7 by the convex lens 2, which effectively reduces the incidence of the incident light. It is something to be used. Here, numerals 3 and 4 are Sin, film, and 5 is Si.
The substrate 6 is a light shielding film. In FIG. 1(b), the incident light is effectively utilized by reflecting the light 1 incident on the light shielding part by a condenser 8 and concentrating it on the photosensitive part 7. In FIG.

However, the following points were not considered. For example, when using a convex lens in Figure 1 (a), the lens is constructed from resin, etc., but this technology is a new technology unique to solid-state imaging devices, and no consideration has been given to the difficulty or simplification of lens formation. . In addition, the photosensitive section 7
Since the lenses are provided correspondingly, adjacent lenses are in contact with each other on the light shielding part. Since the shape of the lens tends to change near this contact point, the direction of the refraction of light incident on this area varies from pixel to pixel, resulting in variations in sensitivity, but this point has not been taken into consideration. Further, when using the condenser 8 shown in FIG. 1(b), no consideration was given to the difficulty in forming a condenser having such a shape.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a solid-state imaging device that can easily utilize light incident on a light-shielding portion effectively and without problems such as variations in sensitivity.

[Summary of the invention]

According to the present invention, a lens is formed on a light shielding part in order to eliminate unevenness in sensitivity from pixel to pixel due to variations in the shape of the lens on the light shielding part, and to eliminate difficult-shaped chambers.

The formation means can be achieved by using techniques such as etching the SiO film 3.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

FIG. 2 is a sectional view of a solid-state imaging device showing an embodiment of the present invention. In this embodiment, a concave lens 9 is provided on the light shielding part 6. According to this embodiment, the light 1 incident on the light shielding part 6 is focused on the photosensitive part 7 by the concave lens 9, and can be used effectively. Further, according to this embodiment, sensitivity variations do not occur due to changes in lens shape due to the lenses 2 coming into contact with each other on the light shielding portion 6.

3(a) and 3(b) show an example of a process for forming the lens 9 shown in FIG. 2. FIG. First, Figure 3 (a)
As shown in FIG. 2, the photosensitive portion 7 is selectively formed so as to be covered by the photoresist 10. As shown in FIG. Next, the S i O film 3 is wet-etched to form a concave lens 9 shown in FIG. 3(b). As described above, according to this embodiment, lens formation can be easily performed.

FIG. 4 is a sectional view of a solid-state imaging device showing another embodiment of the present invention. The difference from the embodiment shown in FIG. 2 is that by optimizing the shape of the concave lens 11 on the light shielding part 6, the light 1 incident on the light shielding part 6 can be used more effectively. In this embodiment, in order to condense the light incident on the light shielding part 6 onto the photosensitive part 7, it is necessary to bend the incident light significantly at the center 12 of the light shielding part 6. For this purpose, it is necessary that the incident angle θ (0@≦θ≦906) has a small value below a certain level at the center 12 of the concave lens 11. In the embodiment shown in FIG. 2, the incident angle θ of the light incident on the center of the concave lens 9 is approximately 90'', so it is hardly bent and cannot be focused on the photosensitive area. According to this embodiment, the incident angle 0 of light to the center 12 of the concave lens is set to a small value below a certain level, and the lens 11 as shown in FIG. It is also possible to effectively utilize the light that enters the area.

FIG. 5(a) is a cross-sectional view of a solid-state imaging device showing another embodiment of the present invention. This embodiment differs from the embodiments shown in FIGS. 2 and 4 in that the light shielding part 14 This is to condense the light onto the photosensitive section 7 by using the reflection of the light incident thereon. By reflecting the light incident on the light shielding part 14 by the light shielding part 14 and the reflecting plate 15 and focusing it on the photosensitive part 7, the light of the light shielding part can be utilized. The 5in2 film 13 can be formed by taper etching. Note that Fig. 5(b) is similar to Fig. 5(b).
It is a top view of (a).

FIG. 6 is a sectional view of a solid-state imaging device showing another embodiment of the present invention. The difference between this embodiment and the embodiment shown in FIG. 5 is that the light shielding part 16 has an upwardly convex shape. Similarly to the embodiment shown in FIG.
It is possible to effectively utilize the light that has entered the light shielding section.

FIG. 7 is a sectional view of a solid-state imaging device showing another embodiment of the present invention. This embodiment differs from the embodiment shown in FIG. 5 in that the reflecting plate 17 is shaped downwardly.
In addition to being able to reflect the light 18 by the reflecting plate 17 and focusing it on the photosensitive part 7, the light 18 reflected by the photosensitive part 7 can also be focused on the photosensitive part 7 by the reflecting plate 17, and the light that enters the light shielding part can be effectively used. can. Further, the reflecting plate 17 can be easily formed in the same manner as in the embodiment shown in FIG.

FIG. 8 is a sectional view of a solid-state imaging device showing another embodiment of the present invention. The difference between this embodiment and the embodiment shown in FIG.
By providing 0, the light can be focused on the photosensitive section 7. This allows for more effective use of incident light, and
It is possible to prevent false signals from being generated due to light entering the light shielding part 4. Note that the light shielding plate 20 can be easily formed by a technique called contouring.

FIG. 9 is a sectional view of a solid-state imaging device showing another embodiment of the present invention. This embodiment differs from the embodiment shown in FIG. 2 in that a lens 9 is provided on the filter 21. Similarly to the embodiment shown in FIG. The light incident on the part can be effectively used.

10 is a cross-sectional view of a solid-state imaging device showing another embodiment of the present invention. This embodiment differs from the embodiment shown in FIG. 2 in that a filter 22 is provided on the lens 9. . Similarly to the embodiment shown in FIG. 9, this embodiment can be easily formed, and the light incident on the light shielding portion can be effectively utilized. Furthermore, by preventing the filters from touching each other, it is possible to eliminate uneven sensitivity due to lens shape variations near the contact points. Note that the light incident between the filters can be focused on the photosensitive section 7 by the lens 9.

By combining the embodiments shown in FIGS. 2 and 4 to 10 described above, incident light can be used more effectively.

For example, FIG. 11 is a sectional view of a solid-state imaging device showing an embodiment that combines the embodiments shown in FIGS. 4 and 8.

In this embodiment, as in the embodiments shown in FIG. 4 and FIG. Can be formed.

〔Effect of the invention〕

According to the present invention, since the light incident on the light shielding portion can be effectively used, the sensitivity of the solid-state image sensor can be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the prior art, FIG. 2 is a diagram showing an embodiment of the present invention, FIGS. 4 to 11 are diagrams showing other embodiments of the present invention, and FIG. It is a figure which shows the process of lens formation. 1.19... Incident light, 2... Convex lens, 3,4° 13... SiO2 film, 5... Si substrate, 6,14° 16.20... Light shielding film, 7. ... Photosensitive part, 8... Concentrator, 9.11... Concave lens, 10... Photoresist, 15.17... Reflection plate, 18... Reflected light from photosensitive part, d Q Section b Section 7 Section 8 Figure 8

Claims (1)

[Scope of Claims] 1. In a solid-state imaging device comprising a photosensitive section made of a photoelectric conversion element and a light shielding section consisting of a charge readout mechanism including a switch element, means for guiding incident light to the photosensitive section is provided on the light blocking section. A solid-state imaging device characterized by being provided with. 2. A solid-state imaging device according to claim 1, further comprising a reflective layer that reflects light reflected from the light shielding portion to the photosensitive portion.