JPS63312671A - Charge transfer image sensor - Google Patents

Abstract

PURPOSE:To prevent the irregularity of a sensitivities of charge transfer image sensors each made by bonding a color filter having a conductive light shielding layer on a transparent substrate by forming one or more monochromatic color filters in a removed part of the shielding layer of the top of a charge detection floating diffused layer. CONSTITUTION:A charge transfer image sensor has many photoelectric conversion regions, a charge transfer region and charge detection N-type floating diffused layer 2 on a P-type substrate 1. A color filter 4 is bonded similarly to a conventional one through an epoxy adhesive 3 on the sensor. A chromium shielding layer 5 is removed over the top 100mum<2> of the layer 2 of 10mum<2> to prevent a floating electrostatic capacity to the layer 2. When the layer 5 on the layer 2 is removed, a state that a bias charge is injected is obtained under the condition that a solar light is incident, thereby causing a normal operation to be lost. Then, color filter elements 6, 7, 8 provided at blue, red and green valid sections are laminated in the opening of the layer 5 on the layer 2 to shield a light by the filter elements.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a charge transfer imaging device, and more particularly to a structure of a charge transfer imaging device equipped with a color filter.

[Conventional technology]

As shown in Figure 2, this is one of the solid-state color imaging devices in which a plurality of photoelectric conversion sections are two-dimensionally arranged on a semiconductor substrate, and a plurality of color filters are covered in a mosaic pattern on these photoelectric conversion sections. A charge transfer image pickup device 24 having a plurality of photoelectric conversion units is mounted on a semiconductor substrate by bonding a color filter 20 in which color filter elements are formed in a mosaic shape on a glass substrate with epoxy, urethane, or acrylic adhesive.
A structure glued to the surface is often used.

In such a color filter 20, a light shielding layer 23 made of chrome is provided outside the effective photoelectric conversion region 22 including the floating diffusion layer 21 for charge detection.

This floating diffusion layer 21 prevents unnecessary carriers generated by light incident on a region other than the effective photoelectric conversion section 22 of the charge transfer image sensor from leaking into the effective photoelectric conversion section 22 and deteriorating the image quality. When extremely strong light is directly incident on the floating diffusion layer 21 for charge detection, carriers generated in this portion prevent normal charge detection operation from becoming impossible.

[Problem that the invention seeks to solve]

However, the structure above the floating diffusion layer 21 is as shown in FIG. That is, on the P dielectric substrate 34 having the N-type floating diffusion stone 21, there is a gate electrode 37 via a 5i02 layer 36, and a thick 8i0J! 3
It has 3. A color filter formed on a glass substrate 30 is bonded onto this thick 5i02 layer 33 with an adhesive 32. The color filter has a chromium light shielding layer 31 on the floating diffusion layer 21. In such a structure, for example, the chrome light layer 31 on the glass substrate 30, which is effectively grounded by facing the P-type substrate 34 over a large area, is connected to the N-type floating diffusion layer 21.
The upper part is covered with an adhesive resin 32, and a floating capacitance t35 is provided between the floating diffusion layer 21 and the floating diffusion layer 21. By the way, the diffusion capacitance of this floating diffusion layer 21 is usually a very small value of about 0.02 pF in order to increase the load detection sensitivity, so such floating capacitance 35 cannot be ignored, This increases the capacity by about 30% and reduces the sensitivity to stains. Furthermore, such stray capacitance 35 is
Since the sensitivity varies depending on variations in the thickness of the adhesive resin layer 32, there is a drawback that sensitivity variations occur from device to device in camera devices that use a constant output voltage.

[Means for solving problems]

In a charge transfer image pickup device in which a color filter with a conductive neutral light layer is adhered to at least a transparent substrate on a transparent substrate, the conductive light-emitting layer above the floating diffusion layer for charge detection is removed. Further, it is preferable to obtain a charge imaging device in which a color filter of a single color or more is formed in a portion where the conductive film and optical layer are removed above the floating diffusion layer for charge detection.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention. P-type substrate 1
It has a thin 5in2 film 19 and a gate electrode 0 on top,
On the other hand, this charge transfer imaging device has a P-type substrate 1 having a large number of photoelectric conversion regions and charge transfer regions as well as an N-type floating diffusion layer 2 for charge detection.

A color filter 4 is adhered onto this charge transfer image pickup element via an epoxy adhesive 3 as in the conventional case. As in the conventional color filter 4, a light shielding layer 5 made of chrome is provided to prevent unnecessary light from entering outside the effective photoelectric conversion area and generation of unnecessary carriers. However, in order to prevent this light shielding layer 5 from having a floating capacitance with the floating diffusion layer 2, the upper part 1 of the floating diffusion layer 2 with a diameter of 10μ, a is
The chrome optical layer 5 is removed over a length of 0.0011 m''.

Since the thickness of the adhesive 3 is usually about 3 to 5 .mu.m, the capacitive coupling between the floating diffusion layer 2 and the chrome blocking layer 5 is very small, and the charge detection capacitance of the floating diffusion layer of 5 inches or less is only increased.

On the other hand, if the optical layer 5 on the floating diffusion layer 2 is removed, under normal imaging conditions, the charge detection operation by carriers generated by the incident light will be affected. Since the frequency is very fast at 10 KHz, there is almost no effect, but under conditions such as direct incidence of the main beam, a bias charge is injected and normal operation is impaired.

Therefore, as shown in FIG. 1, three layers of filter elements 6, 7, and 8 for each color, provided in the effective parts of blue, red, and green, are laminated in the opening of the light shielding layer 5 above the floating diffusion R2. Color filter elements are used to achieve light blocking. Although the light shielding effect of such a color filter is poor against the chrome light layer, and only 2 to 5% of light is transmitted, experiments have shown that it is sufficient to maintain normal charge detection operation. Confirmed by.

[Effects of the Invention] As explained above, the present invention prevents the generation of stray capacitance between the floating diffusion layer and the optical layer by removing the optical layer above the floating diffusion layer. By preventing an increase in the charge detection capacitance, it is possible to prevent a decrease in sensitivity and variations in sensitivity. Further, in the area where the chrome blocking layer has been removed, by layering the filter elements of each color formed in the effective area, a light blocking effect can be obtained that does not affect the operation at all.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of an embodiment of the present invention, FIG. 2 is a top view of a conventional charge transfer image sensor, and FIG. 3 is a partial sectional view of a conventional charge transfer image sensor. ]...P type substrate, 2...N type floating diffusion layer, 3...adhesive, 4...color filter, 5...・Chromed medium light layer, 20...
...Color filter, 21...Floating diffusion layer, 2
2...Effective photoelectric conversion area, 23...Chrome and medium light 7iji, 24...Charge transfer image sensor,
30... Glass substrate, 31... Chrome medium light layer, 32... Adhesive, 33...
・Thick 9 ducks, 34...P-type substrate, 35...
... Stray capacitance, 36... Thin SiO□,
37...Gate electrode.

Claims (1)

[Claims] 1. Charge transfer imaging comprising a large number of photo-electric conversion regions, a charge transfer section that transfers charges detected in these photo-electric conversion regions, and a charge detection section using a floating diffusion layer. In a charge transfer imaging device in which a color filter having a conductive light-blocking layer is adhered to at least a transparent substrate on an element, at least the conductive light-blocking layer above the floating diffusion layer for charge detection is removed. A charge transfer imaging device characterized by: 2. The charge transfer imaging device according to claim 1, wherein a color filter is formed on the floating diffusion layer for charge detection in a portion where the conductive shielding layer is removed.