JPS61154283A - Solid image pick-up element - Google Patents

Abstract

PURPOSE:To improve light sensitivity and to eliminate a shading caused by a lens array by providing the lens array and a reflecting layer which collects a light that is focused on the outside part of a photoelectric transfer part to a photoelectric conversion part, corresponding to the photoelectric conversion part. CONSTITUTION:A transparent lens array 25 and a reflecting layer 26 are provided on the phosphorus glass layer 22 of substrate semiconductor 20 corresponding to the photoelectric convession part. By this mechanism, almost 100% of incident light 31 through 33 inputted vertically is collected on a photo diode 11 and incident lights 35 and 36 out of incident lights 34-36 with a large angle of incidence are collected at another part and reflected by a reflecting layer 26 the reflecting light of which is inputted to a diode 16. Therefore, almost 100% of incident lights 34-36 having large angles of incidence are also inputted to the diode 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a solid-state image sensor, and particularly to a solid-state image sensor equipped with a lens array for improving light sensitivity.

[Conventional technology]

Generally, a solid-state image sensor has a photoelectric conversion section, a signal readout section, and an electrically insulating region on the top surface of a semiconductor substrate.
9. An area of 100 m cannot be used as a photoelectric conversion section. FIG. 2 schematically shows the cross-sectional structure of a conventional solid-state image sensor, which is a device called an interline transfer type CCD.

A photodiode 11 , a transfer gate 12 , and a vertical CCD register 13 are formed on the main surface of the substrate semiconductor 20 , a transfer electrode 14 is arranged with an insulating film 21 interposed therebetween, and a vertical CCD register 13 and a vertical CCD register 13 are further arranged with a phosphor glass layer 22 interposed therebetween. An aluminum light shielding layer 15 is provided to shield the transfer gate 14 from light.
is located. If this light shielding layer 15 is not present, the vertical C
During the period when the signal charges are transferred in the OD register 13, charges generated by the incident light are added to the signal charges, so that a white vertical line called a smear appears on the reproduced image.
Image quality deteriorates significantly.

The light shielding layer 15 is provided to prevent this, and specifically, among the incident lights 31 to 33 corresponding to one pixel pitch (interval between photodiodes), only the incident light 32 enters the fort diode 11, Incident lights 31 and 33 pass through the light shielding layer 15
The light is reflected by the light so that it does not enter the photodiode 11. Therefore, in conventional solid-state image sensors, the area having a photoelectric conversion function for incident light, that is, the aperture ratio is approximately 20 to 40% of the total area. This has resulted in drawbacks such as a decrease in light sensitivity and, if the object is a point light source such as a star, it may not appear in the reproduced image.

Methods for eliminating such drawbacks of conventional solid-state image sensors are disclosed in Japanese Patent Application Laid-open No. 57-9180, Japanese Patent Application Laid-Open No. 57-124485, Japanese Patent Application No. 57-229039, filed by the same applicant as the present invention.
This was proposed in Japanese Patent Application No. 58-147534.

FIG. 3 is a sectional view of a solid-state image pickup device disclosed in an embodiment of the specification of Japanese Patent Application No. 147534/1982. A lens array consisting of first and second transparent resin layers 23 and 24 is formed on the solid-state image sensor. Resin layer 2
3 and the radius of curvature of the resin layer 240 are appropriately determined so that approximately 100 inches of light incident on the lens array is focused on the photodiode 11. Therefore, in this structure, the incident light 31 and 3 that was reflected by the light shielding layer 15
3 will also be incident on the photodiode 11. As a result, the area having a photoelectric conversion function for incident light, that is, the aperture ratio, can be made close to IOOs, and the photosensitivity can be improved compared to conventional solid-state image sensors.

In the method of improving photosensitivity by forming the lens array shown in FIG. 3 on a solid-state image sensor, normally, the incident light is When the light is incident almost perpendicularly as in .about.33, approximately 100 beams of light incident on the lens array are focused on the photoelectric conversion section, so there was no problem with the effect of improving photosensitivity.

[Problem that the invention seeks to solve]

However, in an imaging device equipped with a solid-state image sensor using this method, when the aperture value of the lens used to form an optical image is small, the light sensitivity varies depending on the planar position of the photoelectric conversion section on the solid-state image sensor. The problem was that they were different. For example, in FIG. 3, when the photodiode 11 is located at the center position on the solid-state image sensor, the incident light beams 31 to 33 are incident almost perpendicularly to the lens array.
33 is incident on the photodiode 11, whereas when the photodiode 16 is located at the end above the fixed image sensor, the incident light on the lens array 34-3 is incident on the photodiode 11.
Since the incident angle θ of 6 becomes large, the incident light rays 35 and 36
The light is not incident on the photodiode 16, but is focused on another part. Therefore, the proportion of light incident on the lens array that is incident on the photodiode depends on the planar position of the lens array on the solid-state image sensor, and decreases from the center to the edge. However, there is a drawback that shading occurs.

An object of the present invention is to provide a solid-state image sensor that has good light sensitivity due to the provision of a lens array and is free from shading caused by the provision of the lens array, that is, differences in light sensitivity due to the planar position on the solid-state image sensor. It's about doing.

[Failure to solve the problem]

The present invention provides a solid-state imaging device comprising a photoelectric conversion section formed in a mosaic shape on the same semiconductor substrate and a readout section for a signal photoelectrically converted in the photoelectric conversion section, in which a light condensing section corresponding to the photoelectric conversion section is provided. A transparent lens array having a function, and a reflective layer that reflects light focused on a portion other than the photoelectric conversion section by the lens array and focuses the reflected light on the photoelectric conversion section. Whether it's a solid-state image sensor. 1. [Function] In the present invention, 3. First, by providing a lens array on a conventional solid-state image sensor, the amount of light incident on all the photoelectric conversion functions on the solid-state image sensor increases; By providing a reflective layer that reflects light focused on a part different from the photoelectric conversion part and focuses the reflected light on the photoelectric conversion part, the aperture value of the lens used to form an optical image can be reduced. Even if the angle of incidence of the light incident on the array differs greatly depending on the planar position on the solid-state image sensor, the ratio of the light incident on the lens array to the photoelectric conversion section becomes uniform regardless of the planar position.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

〜Nobu＼＼ FIG. 1 is a sectional view of an embodiment of a solid-state image sensor according to the present invention. In place of the lens array consisting of the first and second resin layers 23 and 24 in the example shown in FIG. 3, a transparent lens array 25 and a reflective layer 26 are provided on the phosphor glass layer 22 of the substrate semiconductor 20. It is. Since the other structural parts are the same as those in FIG. 3, they will be explained using the same numbers. The lens array 25 has the same function as the lens array in the previous example, and almost 100% of the vertically incident incident lights 31 to 33 is focused on the photodiode 11, and also focuses the incident lights 34 to 36 having a large angle of incidence. Among them, incident light 35 and 36 are focused on a portion different from the photodiode 16.

However, these incident lights 35 and 36 are reflected by the reflective layer 26, and the reflected lights are incident on the photodiode 16. Therefore, approximately 100 of the incident lights 34 to 36 having a large angle of incidence are incident on the photodiode 16.

In the embodiment shown in FIG. 1, the reflective layer 26 had a triangular cross-sectional shape, but the reflective layer 26 has a trapezoidal cross-sectional shape or a trapezoidal cross-sectional shape with a curved periphery.

It is clear that the present invention also includes a solid-state image sensor having a reflective layer made of a material that reflects light only at the periphery. Further, in the embodiment, a case where the solid-state image sensor is an interline transfer type CCD is shown, but it is clear that the present invention also includes the case of other solid-state image sensors.

〔Effect of the invention〕

As described in detail above, the solid-state imaging device according to the present invention includes:
By providing a lens array and a reflective layer on a conventional solid-state image sensor, it has good light sensitivity, and it is possible to reproduce objects with point light sources such as stars in the reproduced image. It has the characteristic that there is no shading caused by.

[Brief explanation of drawings]

Claims (1)

[Claims] (1) In a solid-state image sensor that includes a photoelectric conversion section formed in a mosaic shape on the same semiconductor substrate and a readout section for a signal photoelectrically converted in the photoelectric conversion section, a light collecting function is provided corresponding to the photoelectric conversion section. a transparent lens array having;
A solid-state image sensor, comprising: a reflective layer that reflects light focused on a portion other than the photoelectric conversion section by the lens array and focuses the reflected light on the photoelectric conversion section.