JPS58114684A - Solid-state image pickup element - Google Patents

Abstract

PURPOSE:To improve the sensitivity of a solid-state image pickup element regardless of the form of the pickup element, by providing periodically plural color separating filter regions on a single side of a transparent substrate and at the same time distributing plural condensers along the filter regions to condense the beams passed through those filter regions. CONSTITUTION:A photodetecting part 51 is formed to a solid-state image pickup element 56 by a diffusing layer, and a color separating part 52 is formed with coloring matters, etc. on the substrate of a color separating filter 55 as if the part 52 covered over the part 51. At the same time, a light shielding part 53 is formed at other parts. Then plural lens 54 are aligned on the substrate of the filter 55 via a surface protecting film 57 and in response to a color separating part 42. The filter 55 and the element 56 are fixed to each other with a transparent adhesive 58. The beams transmitted through the part 52 are condensed by the lens 54, and the effective light transmitting area of the element 56 is set equal to a light sensing part. Thus the sensitivity of the element 56 is improved regardless of the form of the element 56.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solid-state image sensor, and more particularly to an improvement in a color separation filter mainly used for colorizing a solid-state image sensor.

FIG. 1 shows an example of the basic configuration of a solid-state image sensor.

In this device, the imaging section is a two-dimensional array of 7 photodiodes 1 formed by a PN junction, and electrical signals generated by photoelectric conversion in the photodiodes are sent to a vertical switch 6, a vertical selection line 2. Vertical signal line 3. It is read out by the horizontal shift register 6 and the vertical shift register 4. The vertical shift register 4 in a configuration like the first region can usually be composed of a MOS shift register, and the horizontal shift register 6 can be composed of a MOS shift register or a COD shift register.

In many cases, the diffusion layer 7 is formed on the semiconductor substrate.

In the progress of such solid-state imaging devices, one of the major technological issues has always been the resolution characteristic, and this characteristic is determined by the photodiodes that are integrated over a predetermined area for imaging. Determined by the number of

Therefore, as a result of efforts to increase the density, it is now possible to reduce the vertical and horizontal combing periods of photodiodes to about 10 microns and 20 microns, respectively. ) This is made possible by using the most minute processing technology among all other types of roads.

However, the characteristics of an image sensor depend on such processing.
Even with the miniaturization of technology, unresolved technical issues remain. That is, the problem is a decrease in the ratio of the light-receiving area of the photodiode section that performs the photoelectric conversion to the total imaging area. As shown in FIG. 2, the area of the photosensitive area 7 of the photodiode is less than 50% of the total area even when the degree of integration is relatively low, and the number of integrated stages in the horizontal and vertical directions is about 4oo and 600, respectively. Then, the area of the photo-sensing region 7 becomes 20-30%. In the case of the configuration example shown in FIG. 1, vertical selection lines 2. This is because it is necessary to provide the vertical switch 6 and the vertical signal line 3. Furthermore, when a so-called overflow drain structure is incorporated to prevent abnormal operation due to excessive light input, the ratio of the light receiving portion of the photodiode to the total area further decreases.

When a color solid-state image sensor is constructed by combining a color separation filter and a solid-state image sensor, color separation sections corresponding to the light sensing area 7 of the light receiving section shown in FIG. and a color separation filter array attached to the surface thereof can be combined as shown in FIG.

FIG. 3 shows the configuration of a conventional color solid-state image sensor. In the figure, 31 is a diffusion layer of a photodiode in an image sensor 36, and 32 is a color separation filter 35.
33 is a light-shielding area between the color separating units 32, and 34 is an area between the image sensor 36 and the color separating filter 36.

For the diffusion layer 31 of the photodiode which becomes the light sensitive cheek part,
A color separation section 32 of a color separation filter is combined. The dimensions of the dye part must match the dimensions of the photodiode part. Therefore, the size of the diffusion layer region 31 which becomes the light-sensitive cheek in the semiconductor chip is smaller than the size of the image sensor.
When the size of the diffusion layer becomes smaller, the sensitivity decreases due to a decrease in the light receiving area. Further, when a stripe or mosaic color separation filter for colorization is attached as shown in FIG. 3, one color separation 932 must be aligned with the diffusion region 31. The color separation section 32 is usually composed of a natural or synthetic polymer compound layer or an interference filter dyed with an organic synthetic dye or the like.

The region 34 between the color separation filter 35 and the image sensor 36 may be a void, but may also be filled with a colorless transparent material. The colorless transparent material is often an adhesive for fixing the color separation filter 36 to the image sensor 36. The light shielding area 33 other than the color separation N532 of the color separation filter 36 is usually formed of a vapor deposited film of metal chromium or the like.

As shown in FIG. The light utilization rate is about 20 to 30%.

The present invention attempts to significantly alleviate the above-mentioned decrease in sensitivity due to the increase in the density of image pickup devices by using a new configuration of a color separation filter formed on the front surface of the image pickup device.

FIG. 4 shows the basic configuration of a solid-state image sensor according to the present invention. As shown in FIG. 4, the solid-state image sensor of the present invention includes a color separation section 42 that covers the photosensitive cheek part 41 of the image sensor 46, and a color separation section 42 that directs the light transmitted through the same color separation section 42 onto the photosensitive area 41 on the image sensor 46. It is characterized by having a color separation filter equipped with a condensing means 44 for converging light.

With this configuration, whereas in the conventional image sensor, only a light separation area with a light transmission area approximately the same size as the light-sensitive cheek area could be used, in principle, the entire area of the image sensor can be used. can be made into a light-transmitting region, and the efficiency of light utilization is greatly increased. The condensing means 44 is preferably made of a transparent dielectric material such as synthetic resin, and has a high refractive index. Due to the condensing action of the condensing means 44, the light transmitted through the color separation section 42 is condensed onto the light-sensitive cheek section 41 of the image pickup device 4e.The solid-state image pickup device is most commonly used in the production of semiconductor integrated circuits. The color separation filter can be manufactured using a photolithographic technique, for example, by uniformly forming a light-transmitting dielectric layer on the surface of the color separation filter.

FIG. 6 shows an embodiment of the solid-state imaging device of the present invention manufactured by such a method, and shows a cross-sectional view of the color separation filter that forms the light collecting structure and the portion to which the imaging device is fixed. . A feature of this solid-state image sensor is that it uses a translucent lens body to collect the light that has passed through the color separation filter onto the photosensitive cheek area. In the figure, 51 is the image sensor 5
6 is a light-sensitive cheek area formed by a diffusion layer, 52 is a color separation area such as a pigment formed on the substrate of the color separation filter 55, 63 is a light shielding area such as metal chromium, and 64 is a color. It is a lens body made of a transparent resin formed on a color separation filter 56 through a surface protection film 5 formed to protect the surface of the separation filter. Note that a transparent adhesive 68 is interposed in the area between the color separation filter 66 and the image sensor 66 to fix the two to each other.

In the solid-state virtual image element having such a configuration, when light is incident, the lens body 64 does not touch the light rays corresponding to the light-sensitive cheek part 51 of the image pickup element, but extends beyond the original sensor g61 to the rays of light that are deviated from the light rays. By focusing the light on the light-sensitive cheek portion 61, the utilization rate of the light can be increased and the sensitivity can be made the same.

It should be noted that the lens body 64 only needs to have a curved surface portion that focuses light onto the light sensor 851, and does not necessarily need to be an accurate spherical surface.

FIG. 6 shows a sectional view of a main part of a solid-state imaging probe according to another embodiment of the present invention. A feature of this solid-state image sensor is that it uses a light reflector to collect the light that has passed through the color separation filter onto the photodetector. In the figure, reference numeral 61 denotes a light-sensitive cheek portion, which is a diffusion layer formed on the image sensor 66;
2 is a color separation area formed on the substrate of the color separation filter 66, such as a dye, 63 is a light shielding area such as a vapor deposited film of metal chromium, etc., and 64 is a surface protection film 87 of the color separation filter.
A transparent dielectric layer 68 is formed in the color separation filter 66 through the transparent dielectric layer 64, and is a light reflector made of aluminum or the like formed in the groove 69 of the transparent dielectric layer 64.

A solid-state imaging device having such a configuration can be manufactured as follows. Color separation area 6 using interference filter method on glass substrate
2, a dielectric layer 64 is formed via a surface protective film 67.
grooves 6 are formed in the dielectric layer 64 using well-known photolithographic techniques.
9 will be provided. Thereafter, a metal film 68 such as aluminum is vacuum-deposited on the entire surface of the dielectric layer 64, leaving the metal film 68 in the groove 69 of the dielectric layer 64, and depositing the metal film at a location corresponding to the photosensitive cheek of the image sensor. 68 is removed. Colors like this ^
A filter is attached to the image sensor 66 (Ml).

Due to the condensing structure of the solid-state virtual image element having the above configuration, as shown in FIG.
By focusing not only light rays a but also light rays deviated from the light sensitive cheek part 61 on the light sensitive cheek part 61, it is possible to achieve a sensitivity approximately six times that of the conventional example.

As explained above, the present invention can be applied regardless of the form of the solid-state image sensor, and has excellent photosensitivity in both the cases where a lens effect is used as a light focusing means and when a single reflection effect is used. The solid-state image sensing device of the present invention is industrially useful.

[Brief explanation of the drawing]

The first figure is a diagram showing the basic configuration of a solid-state virtual image device, the second figure is a diagram showing the imaging section of the same element, the third figure is a cross-sectional view of the main part of a conventional solid-state image sensor, and the fourth figure is the invention of the present invention. FIG. 5 is a cross-sectional view of a main part of a solid-state virtual image device according to an embodiment of the present invention, and FIG. 6 is a cross-sectional view of a main part of a solid-state virtual image device according to another embodiment of the present invention. FIG. 2 is a cross-sectional view of a main part of a solid-state image sensor. 41.51.61...Light receiving section (diffusion section), 4
2.52.82...Color separation section, 43,53゜6
3... Light shielding part, 44... Light condensing means, 6
4...Lens body, 64...Transparent dielectric, 6B...Light reflector, 45,55.65...
...Color separation filter, 46°66.66...
・Image sensor. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 6 Figure 2 Figure 3 Figure 1 Figure 4 Figure 5

Claims (1)

[Scope of Claims] (1) A plurality of color separation 'p% filter areas arranged periodically on one surface of a transparent plate, juxtaposed corresponding to the color separation filter areas, and the color separation A solid-state imaging device characterized by having a color separation filter including a plurality of condensing bodies that condense light that has passed through a filter region. (2) The solid-state image sensor according to claim 1, wherein the light condenser is constituted by an optical lens. (3) The solid-state image sensor according to claim 1, wherein the light condenser has a surface that reflects the light transmitted through the color separation filter region. (4) Light condenser and color separation filter 2. The solid-state imaging device according to claim 1, wherein a transparent adhesive is interposed between the first and second regions.