Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Patent
1991-05-17
1993-08-24
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
357 30, 257431, H01J 4014
Patent
active
052391728
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to the structure and the method for manufacturing of a filter in case a solid-state imaging device is produced by bonding imaging sensor with color filter or monochromatic filter by adhesive agent, and in particular to a light converging filter and the method for manufacturing the same for increasing converging efficiency to light receiving unit of imaging sensor.
BACKGROUND OF PRIOR ART
In the method for manufacturing a solid-state imaging device, there are two types of method: The method to form color filter directly on solid-state imaging sensor (on-chip method), and the method to form color filter on a transparent substrate such as glass substrate and to bond this with solid-state imaging sensor by adhesive agent (bonnding method).
In order to increase the sensitivity of solid-state imaging device, it has been attempted in recent years to mount lens on front surface of solid-state imaging sensor and to improve the efficiency by increasing the converging property to the light receiving unit. FIG. 9 shows a cross-sectional view of such solid-state imaging device. As shown in this figure, each of the pixels 53 of color filter 52 is arranged on the front surface of light receiving units 51 of CCD 50, and lenses 54 are provided in alignment with each pixel 53. As the material suitable for forming lenses on color filter 52, there are various types of photosetting or thermosetting resin. Because the difference of refractive indices between the air (refractive index.apprxeq.1) and resin layer (refractive index.apprxeq.1.5 to 1.6) is relatively big, it is possible to obtain high converging effect for incident light 55 coming directly to lens 55 through the air 56.
In contrast, the refractive index of the photosetting or thermosetting resin used as adhesive agent in the bonding method is 1.5 to 1.6, and the difference of refractive index from that of lens unit formed on solid-state imaging sensor is too small. Accordingly, if it is in the same arrangement as on-chip method, converging effect is not obtained almost at all.
The object of the present invention is to offer a light converging color filter or monochromatic filter to be used for the bonding method and a method for manufacturing converging filter to solve the above problems of the conventinal bonding method.
SUMMARY OF THE INVENTION
To attain the above object, the light converging filter according to the present invention is a color filter or monochromatic filter to be used on imaging sensor by bonding, and it is characterized in that there are provided at least two resin layers adjacent to each other on transparent substrate and having different refractive index, and that the boundary surfaces of these resin layers are prepared in such curved form that the incident light is converged to the light receiving units of imaging sensor.
In this case, typical arrangement is that a resin layer in convex form with relatively low refractive index is provided in alignment with upper or lower portion of a light shielding layer of color filter or monochromatic filter, and another resin layer with relatively high refractive index is furnished on the surface of the above resin layer.
According to the first method for manufacturing converging filter, photosetting resin is coated on a transparent substrate before or after forming the filter layer, and only the resin at the boundary of color element or at upper or lower portion of light shielding layer is hardened by exposing to light to prepare it in convex form. Then, another resin layer having higher refractive index than that of the above photosetting resin is coated and the surface is flattened.
In this case, it is preferable to adjust the inclination of the edge of convex portion formed through selective exposure and curing of photosetting resin by heating it to its softening point after light curing.
According to the second manufacturing method, photosetting resin is coated on a transparent substrate before or after the formation of filter layer, and onl
REFERENCES:
patent: 4667092 (1987-05-01), Ishihara
patent: 4689652 (1987-08-01), Shimada et al.
patent: 4959533 (1990-09-01), Yamazaki et al.
patent: 5081346 (1992-01-01), Narabu et al.
Mori Hajime
Yokota Toshio
Dai Nippon Printing Co. Ltd.
Nelms David C.
Shami K.
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