JPS6057711B2 - solid state imaging device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a solid-state imaging device capable of capturing color images.

In recent years, with the development of semiconductor technology, especially integrated circuit technology, there has been active development of image pickup devices to replace conventional image pickup tubes, and devices that can be used practically as black and white cameras are already on the market. At the same time, development of color cameras using a single image sensor by equipping this image sensor with three color filters of green, blue, and red is also active, but it is still a step forward in terms of resolution, sensitivity, and color separation. This is the place.
One of the causes of these problems in sensitivity and color separation will be explained with reference to FIG. Those using conventional three-color filters are
It consists of an imaging device plate A of the imaging MOS type or CCD type, etc., a color filter B, and an adhesive layer C that adheres the two. The basic composition of the image sensor plate A is a silicon substrate 1, an oxide film 2, transparent gate electrodes 3, 3...
It consists of

The width of this gate electrode 3 is about 10 μm, and the interval between them is about 6 μm. When a voltage is applied to this gate electrode 3, a potential well capable of accumulating charges is formed on the surface of the substrate 1 directly under the gate electrode 3. When a portion is irradiated with light, photocharges generated in accordance with the amount of light are accumulated and the imaging function is activated. Therefore, this gate electrode 3 has a function as a picture element, but since it is necessary to separate each adjacent picture element, the electrodes 3 are electrically insulated from each other. To enable color imaging, it is necessary to synchronously irradiate each picture element with light of a different color, so a color filter B is bonded to the image sensor plate A.

This color filter B has chromium films 6, 6, etc., which do not transmit light, on a thin transparent glass plate 5 with a thickness of about lwn, at locations corresponding to the spacing between the gate electrodes 3, 3, etc. of the image sensor plate A. Filter films 7, 8, and 9 of green, blue, and red, which are the three primary colors of light, are formed in transparent areas where the chromium films 6, 6, . . . are not present. These filter films 7, 8, and 9 are made of gelatinous organic resist mixed with respective dyes, and a transparent intermediate layer is added to prevent color interference when forming each filter film 7, 8, and 9. 10, 10 are provided, and a surface protective film 11 of the same quality is formed on the surface of the red filter film 9.The reason for providing the chromium films 6, 6, etc. is that the chromium films 6, 6, etc. This is to prevent a phenomenon in which photocharges generated by the light stochastically flow into adjacent picture elements, making complete color separation or picture element separation impossible.Image sensor plate A and color filter B are bonded together. Although it is better for the adhesive layer C to be thin, it actually has a thickness of about 10μ.However, due to the presence of the chromium films 6, 6...
The light that arrived at ... did not contribute to the imaging operation at all, resulting in a decrease in the sensitivity of the imaging device.

The present invention solves such problems and provides an imaging device that uses incoming irradiation light without wasting it for imaging operations and is capable of color separation and pixel separation.

FIG. 2 is a cross-sectional view of one embodiment of the device of the present invention, and all figure numbers are the same as in FIG. 1.

The difference from FIG. 1 is that instead of providing chromium films 6, 6, etc., the gate electrodes 3, 3 of the image sensor plate A are provided on the transparent glass plate 5.
A concave groove with a width of approximately 6 μm is formed so as to form a concave lens corresponding to the spacing of . In the case of the example, filter membranes 7 adjacent to each other within this groove
, 8, and 9 are at least slightly overlapped. In order to form concave lens-shaped concave grooves on the transparent glass plate 5, approximately the desired concave lens can be obtained by isotropic etching using liquid etching. Specifically, a slit of about 3 μm, which is about half the width of this concave groove, is formed in the etching-resistant film of the glass plate 5, and by using a hydrofluoric acid-based etching solution, a slit with a depth of about 6 μm and a focal length of about 6 μm is formed. A groove with a thickness of approximately 10 μm, which is approximately equal to the thickness of the adhesive layer C, is obtained. ~According to such a structure, the light that reaches this groove is passed through the color filters 7, 8, and 9, respectively.
It reaches the concave lens part through the lens, and there, as shown by the arrow, is bent toward the gate electrodes 3, 3, . It happens.

As explained above, in the present invention, all the light that has arrived between the picture elements of the image sensor is guided to the picture elements, so the efficiency is extremely high, and since there is no light irradiation between the picture elements, color separation is possible. Picture elements are completely separated, allowing for high resolution.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an existing imaging device, and FIG. 2 is a sectional view of the device of the present invention, in which A is an image sensor plate, B is a color filter, C is an adhesive layer, 5 is a transparent glass plate, and 6 is a sectional view of an existing imaging device. chrome film, 7,
8 and 9 indicate filter membranes, respectively.

Claims (1)

[Claims] 1. An image sensor plate having photoelectric conversion units at predetermined intervals;
and a color filter disposed close to the element plate, each filter having a transparent substrate, each of which has grooves at locations corresponding to the spacing between the photoelectric conversion sections of the image sensor plate. A concave lens portion is provided in the groove, and filter films of different colors are provided from approximately the center of each groove to approximately the center of the adjacent groove, and the filter film at each groove position is provided with a filter film of a different color. A solid-state imaging device characterized by guiding the light passing through the image to an adjacent photoelectric conversion section by the action of a concave lens.