JPS58220106A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To improve an aperture rate by providing a filter array having lenses which focus incident light and allow the transmission of light of only one color among red, green and blue to the photoelectric converters disposed on a semiconductor substrate. CONSTITUTION:Photoelectric converters 12 are formed like a matrix on the surface region of a semiconductor substrate 10. A filter array 20 is adhered via an oxide film 19 on the surface of the substrate 10. The array 20 is formed with spherical recesses in accordance with the respective converters 12 on the surface of a light transmittable substrate 22. Light transmittable materials 24, 26, 28 contg. respective dyes for red, green and blue are packed in said recesses. The materials 24, 26, 28 act as color sepn. filters and also act as convex lenses as they have high refractive indices. Therefore, the light which is made incident to the light shielding regions except the converters 12 is converted and is made incident only to the transducers 12. The aperture rate is thus improved without requiring intricate adjustment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solid-state imaging device, and particularly to a solid-state imaging device for color imaging.

In recent years, with advances in semiconductor integration technology, solid-state imaging devices have been used in place of image pickup tubes. Here, in a solid-state imaging device, since the incident light is irradiated onto the photoelectric conversion unit from the gap between the M and the poles formed on the surface, the aperture ratio (the ratio of the amount of light actually photoelectrically converted to the total amount of incident light) is Bad Disadvantages Since vertical and horizontal transfer registers, overflow drains, etc. are shielded from light, the opening ratio is particularly poor.

In order to solve this problem, it is conceivable to arrange a lens array having minute convex lenses corresponding to the famous photoelectric conversion elements above the photoelectric conversion section. By using this convex lens to converge the incident light that goes straight into the light shielding section onto the light weight conversion element, the aperture ratio can be improved.

However, normally 1, the 11 method of each photoelectric conversion element is 10
This is around μm, and it is difficult to form a spherical surface of a convex lens with the same precision. If the relative positioning of this lens array and photoelectric conversion section is not yet performed accurately,
It also happens that the incident light is converged not on the light weight conversion element but on the light shielding area 14. Furthermore, for use in color imaging,
It is also necessary to arrange a three-color color separation filter array above the photoelectric conversion section, and in such a crowded case, it is virtually impossible to align the three relative positions.

This invention was made to deal with two situations.
The purpose of this invention is to improve the aperture ratio in solid-state imaging devices for color imaging.

Hereinafter, one embodiment of a solid-state imaging device according to the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view thereof, and FIG. 2 is a sectional view thereof. Photoelectric conversion elements 12 are formed in a matrix on the surface region of semiconductor substrate 10, and control electrodes 14, vertical transfer registers 16, and horizontal transfer registers 18 are also formed. As shown in FIG. 2, a flat filter array 20 is pasted on the surface of the substrate 10 with an oxide film 19 interposed therebetween. The filter array 20 has a filter section made up of a plurality of filters corresponding to each photoelectric conversion element 12 and a light-shielding frame section. As shown in FIG. 2, the details of the filter section are as follows: a large number of four spherical sections are formed on the surface of a translucent substrate 22, and each of the four sections is made of a transparent material in which red, green, and evening pigments are mixed. A photosensitive material 24, 26, 28 is filled. Here, the substrate 22, the transparent materials 24, 26
．． 28 is made of glass, resin, etc., and is a translucent material 24, 2
A material having a higher refractive index than the substrate 22 is used for 6°28.

In the cross-sectional view of FIG. 2, resistors and the like that should be shielded from light other than the photoelectric conversion element 12 are not shown.

According to such a configuration, the translucent materials 24, 26, and 28 filled in the recesses act as color separation filters, and also act as convex lenses because of their high refractive index.

As a result, as shown in FIG. 3, without the filter array 20, light that would otherwise be incident on the light shielding area other than the photoelectric conversion element is converged and incident only on the photoelectric conversion element. Therefore, the aperture ratio can be improved. Furthermore, since the filter array itself has a lens effect, there is no need to align the filter and lens. Furthermore, since the filter array can be manufactured directly on the semiconductor substrate as part of the manufacturing process for photoelectric conversion elements on the surface of the semiconductor substrate, the relative alignment of the filter array and the photoelectric conversion elements can be performed with high precision. It will be done. Direct manufacturing also prevents the filter array from shifting during use.

Next, a method of manufacturing the lever 17 will be explained with reference to FIGS. 4(a) to 4(d). After the photoelectric conversion element 12 and other necessary elements as an image sensor are formed on the substrate 10, the process shown in FIG.
), a transparent substrate 22 and a photoresist 30 are pasted on the oxide film 19. (7) The photoresist 30 is light-damped through a mask having an opening (here, a horizontally long rectangle) corresponding to each fill.Here, the center of each opening of the mask is aligned with each photoelectric conversion element. The mask and the imaging device are aligned so that they coincide with the center of the filter (
The photorenost in the part corresponding to part 4) is removed.

Next, using the remaining photoresist as a mask, the portion corresponding to the filter is irradiated with a laser beam.

Here, since the portion corresponding to the filter has a rectangular planar shape, the laser beam is irradiated as a horizontal beam by a cylindrical lens or the like. The transparent substrate 22 made of resin or the like is thermally denatured by the laser beam and becomes brittle. Here, since the intensity distribution of the laser beam is a Gaussian distribution, the area on the optical axis undergoes thermal degeneration most strongly, and the degree of degeneration becomes weaker toward the periphery. Therefore, if the surface of the transparent substrate 22 is corroded using a corrosive liquid after being irradiated with a laser beam, the thermally denatured portion will be corroded, and the surface area of the substrate 22 will be corroded as shown in FIG. A spherical recess is formed on the surface.

Then, as shown in FIG. 3D, the photoresist 30 left on the surface is removed, and the recesses are filled with a high refractive index transparent member 24, 26, 28 containing a dye. At this time, filling is divided into three times for each color according to the color classification of filling.

In this second embodiment, the recesses of the light-transmitting substrate 22 are provided with some gaps, but if the recesses are provided closely together, the aperture ratio can still be improved.

Next, a second embodiment of the present invention will be described with reference to FIG. A glass M40 is formed on the element by coating, vapor deposition, etc., a mask 42 having a large number of minute holes is placed on the glass layer 40, and these are placed in a certain type of ion atmosphere.

Here, the masks are stacked so that the centers of the holes and the photoelectric conversion elements 12 coincide. In this way, external ions are diffused into the glass layer 40 by ion exchange with ions inside the glass. Since the pores are very small, the ion diffusion distribution becomes spherical with the pores at the center, and the ion concentration gradually decreases as you move away from the pores. In ion exchange, newly diffused ions enter the glass layer 40.
If the polarizability is smaller than that of the ions inside, the refractive index of the part where the ions are diffused will be lower than that of the original glass layer 40.
Garu. Therefore, if ions that satisfy these conditions are selected and ion exchange is performed, the refractive index decreases in the shape of concentric spheres centered around the hole, resulting in the formation of a convex lens. After this, it is taken out of the atmosphere and the mask is removed. Then, a mask having an aperture corresponding to the size of the filter used in the first embodiment is overlaid, and the dye of the color separation filter is applied onto the glass layer 40. Alternatively, dope with a dye.

The second embodiment manufactured in this manner also facilitates alignment between the image sensor, lens, and filter, and improves the aperture ratio.

In this embodiment, instead of entering the ion atmosphere, the ion beam is passed through the hole in the mask 42 to the glass layer 40.
Ion exchange may also be performed by irradiating with. Furthermore, the size of the region within the glass layer 40 that acts as a lens can be adjusted by controlling the ion diffusion time.

As described above, according to the present invention, it is possible to provide a solid-state imaging device with improved aperture ratio without requiring complicated adjustment.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of one embodiment of a solid-state imaging device according to the present invention, FIG. 2 is a sectional view thereof, FIG. 3 is a diagram explaining the effect, and FIGS. FIG. 5 is a diagram showing the manufacturing process of the second embodiment. 10... Semiconductor substrate, 12... Photoelectric conversion element, 22...
...Transparent substrate, 24,26.28...Transparent member,
3θ photoresist. Applicant Sub-Agent Patent Attorney Takehiko Suzue Figure 4 Figure 3 Figure 2 Continued from Figure 5 Page 1 0 Inventor Shunpei Tanaka 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside of Lympus Optical Industry Co., Ltd. 0 Invention Author Hiroshi Matsui 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside of Lymphus Optical Industry Co., Ltd.

Claims (1)

[Claims] It has a plurality of photoelectric conversion elements arranged in a matrix on a surface area of a semiconductor substrate, and a lens arranged on the semiconductor substrate to converge incident light on a portion corresponding to each photoelectric conversion element, and each lens A solid-state imaging device that includes a flat filter array that passes only one color of red, green, or blue light.