JPH02246586A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a flare signal by covering a part made of a material of high reflection factor other than the light reception part on the upper face of a solid state image pickup element chip with a color filter. CONSTITUTION:The light made incident on a light reception part 2 is separated to spectral components by filters 8 to 10 for red, green, blue light reception as conventional. An anti-reflection filter 17 with which the part other than the light reception part 2 on the upper face of the chip is covered absorbs the light of all wavelengths of incident visible rays. Consequently, the reflected light due to the light made incident on the chip is not generated because of the existence of this antireflection filter 17. Thus, the occurrence of the flare signal is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a solid-state imaging device equipped with a solid-state imaging element chip.

[Conventional technology]

A solid-state imaging device that converts an optical image into an electrical signal uses independent photoelectric conversion elements (i.e., photodetectors or also called pixels) such as photodiodes on a semiconductor substrate.
A device that arranges a large number of photoelectric conversion elements regularly and electrically reads out the amount of light that reaches each photoelectric conversion element, and is used in VTR cameras, copying machines, etc.

A solid-state imaging device mainly consists of primary components. That is, a solid-state image sensor chip having a light receiving section in which a large number of photoelectric conversion elements such as photodiodes are arranged, a scanning circuit (peripheral circuit) that outputs photoelectric conversion information of the photodiodes, electrodes (ponding pads) of the scanning circuit, and an outer lead. (outer lead, external terminal) and inner lead (
A lead frame that has an integral inner lead (also referred to as an internal terminal or bonding post) and electrically connects the solid-state image sensor chip to the outside, and two upper and lower sheets that hold the solid-state image sensor chip and the lead frame. The upper and lower ceramic bodies (i.e.

A lower ceramic substrate on which a lead frame and a solid-state image sensor chip are mounted, an upper ceramic frame having an opening for a storage space for the solid-state image sensor chip), and a lower ceramic frame that covers the opening (light receiving window) of the upper ceramic frame. An optical window (window glass) made of a material such as glass with high light transmittance is bonded to the upper surface of the upper ceramic frame and is used to introduce light into the light receiving section.

The lead frame is 1. Good compatibility with ceramics, for example. 4.
2 alloy (Ni: 42%, Fe: 58% weight base metal)
It is sandwiched between two upper and lower ceramic bodies, and is fixed to the upper and lower ceramic bodies with a low melting point glass such as frit glass.

The solid-state image sensor chip is placed directly on the lead frame, or is placed on the lower ceramic substrate on which the lead frame is placed, within an opening provided in the center of the lead frame.

That is, when electrical continuity is established from both the front and back surfaces of the solid-state image sensor chip, the solid-state image sensor chip is placed directly on the lead frame. On the other hand, when electrical continuity is established only from the surface of the solid-state image sensor chip, it is provided not on the lead frame but on the lower ceramic substrate at the opening of the lead frame. The plurality of bonding pads, which are electrodes formed on the periphery of the top surface of the solid-state image sensor chip, and the plurality of inner leads of the lead frame are composed of a plurality of thin wires made of aluminum (AQ), gold (Au), etc. In other words, they are connected using bonding wires. The plurality of outer leads that are integrally provided on the lead frame each extend horizontally from between the two upper and lower ceramic bodies, and are bent downward almost at right angles to the top surface of the ceramic body a little beyond them. .

In addition, a solid-state image sensor chip has, for example, an AFI wiring on a Si substrate provided with a photodiode, a COD (charge coupled device), etc., an AQ light-shielding film that prevents light from being irradiated to the CCD, and an AQ light-shielding film that prevents light from being irradiated onto the CCD. Color filters and the like are laminated with protective films interposed therebetween.

The color filter is made of an organic resin film such as gelatin or acrylic resin, and usually three types dyed in the three primary colors of red, green, and blue are provided on the photodiode.

Regarding solid-state imaging devices, for example, see Video Information 25-31 published by Japan Industrial Development Corporation, May 1, 1986.
It is written on the page.

[Problem to be solved by the invention]

On the upper surface of the solid-state image sensor chip, that is, on the light-receiving surface, there are a light-receiving part, an Ajl light-shielding film, an AQ wiring, a bonding pad,
There is a Si substrate, etc. The light receiving section includes a light receiving color filter provided on a photodiode.

That is, the parts other than the light receiving part are made of a material with high reflectance. The Si substrate is a silvery white mirror surface, and the AQ is also silvery white and reflects light well. Therefore, when light enters the top surface of the chip, it is reflected by the AQ light-shielding film, Si substrate, AQ wiring, bonding pad, etc., and is then repeatedly reflected and scattered by the inner surface of the package, the glass surface of the optical window, etc. Reflected light enters the photodiode. This phenomenon occurs when a flare signal (light color signal) occurs in contrast to a normal optical signal.

The signal-to-noise ratio S/N decreases, which adversely affects the image.

In particular, in a one-dimensional photo sensor (line sensor) in which photodiodes are arranged one-dimensionally, the area occupied by the part other than the light-receiving part is large compared to the area occupied by the light-receiving part.
For example, the width of a chip is approximately 2 m, while the width of a photodiode is several to several tens of meters.

Conventionally, one-dimensional photosensors that capture black-and-white images use digital signal processing to treat the output as binary values of "1" or "0," so even some flare signals did not pose much of a problem. . However, flare signals pose a serious problem in analog signal processing that attempts to obtain a signal output with several tens to hundreds of gradations, such as in a color-dimensional photosensor that captures color images.

An object of the present invention is to provide a solid-state imaging device that can suppress flare signals caused by reflection on a solid-state imaging element chip and improve image quality.

[Means to solve the problem]

In order to achieve the above object, the solid-state imaging device of the present invention includes the upper surface of the solid-state imaging element chip other than the light-receiving section provided with the light-receiving color filter (that is, the upper surface of the solid-state imaging device chip).

In the solid-state imaging device of the present invention, the solid-state imaging device of the present invention is characterized in that the light-shielding film, substrate, wiring, bonding pad, etc. are covered with an anti-reflection color filter. A light-shielding film made of a highly reflective material other than the light-receiving part on the top surface of the
Since the substrate, wiring, bonding pads, etc. are covered with the color filter, it is possible to prevent flare signals from being generated due to reflection of incident light by these parts.

Of the light incident on the color filter, light with a wavelength equal to the color of the filter is transmitted through the filter, and other light is absorbed by the filter itself. Although a certain degree of effect can be achieved with a single layer of filters, the effect becomes greater when two or more layers of filters are stacked.

For example, if the third layer of red, green, and blue filters are stacked, the color of the five antireflection filters will be black because the three colors of red, green, and blue are mixed, and all wavelengths of visible light will be incident on the filter. Light is absorbed by the filter and no incident light is reflected, so
If this filter is placed on the entire chip other than the light receiving part,
Flare signals caused by light incident on the chip no longer occur.

〔Example〕

FIGS. 3(a) to 3(d) are diagrams showing the structure of a one-dimensional photosensor which is a solid-state imaging device to which the present invention is applied. The imaging device and VC portion (container) is referred to as a package PKG.

In the same figure, (a) shows the solid-state imaging device DVC connected to the chip C.
FIG. 3 is a partially cut-away top view when viewed from the light-receiving surface side of the HI.

Based on the top view (a), (b) is a side view when viewed from above, (C) is a sectional view taken along the Q-8 cutting line, (d
) is a partially omitted side view when viewed from the right side, (e) is a 8-
8 is a partially omitted cross-sectional view taken along the cutting line.

The window glass GLS is a translucent sealing plate and is made of a glass material such as borosilicate glass (B z O3·Sin).

The solid-state image sensor chip CHI is made using monolithic semiconductor integrated circuit technology, and the surface on the window glass GLS side (light-receiving surface)
A plurality of photoelectric conversion elements such as photodiodes are arranged on the substrate, and the back surface is bonded to the lower ceramic substrate LOW with an adhesive such as a silver paste material.

The lower ceramic substrate LOW has a mount portion MNT, which is a recess for mounting the solid-state image sensor chip CHI, in the center thereof, and this recess allows the solid-state image sensor chip C to be mounted.
The height relationship between HI and inner lead IL is adjusted.

The upper ceramic frame UPP has a light-receiving window WDW cut out in the center so that external light hits the solid-state image sensor chip CHI.

The lead LD is a lead for electrically connecting between the solid-state image sensor chip CHI and an external application circuit such as a printed wiring board, and is a lead for electrically connecting the solid-state image sensor chip CHI to an external application circuit such as a printed wiring board.
A frit glass FLT is fixed in between. The lead LD includes an inner lead part IL for connection with the solid-state image sensor chip CHI and an outer lead part O for connection with an external circuit.
L, and both lead portions are formed continuously (integrally) with the lead frame REF. The 16 inner leads IL have the same tip shape and are located in the middle, and the 4 inner leads ILL have a round hole in the center and have a thick tip shape and are located in the 4 corners. inner lead I
There are a total of 20 L2s.

This special shape of the inner lead IL2 is useful for lead position pattern recognition during automatic wire bonding.

The bonding wire WIR is a metal wire made of Al, Au, etc. for electrically connecting the inner lead IL and the bonding pad of the solid-state image sensor chip CHI. Due to the recess of the mount part MNT, the upper surface of the solid-state image sensor chip CHI is at a lower position than the upper surface of the inner lead IL, so the bonding wire WIR hangs down and comes into contact with the edge of the solid-state image sensor chip CHI, causing a short circuit. Such defects can be prevented.

Reference holes HL1 and HL2 are formed in the metal plates REFI and REF2. Solid-state image sensor chip CHI
When is automatically die-bonded to the mount part MNT, its positioning is performed based on the reference holes HL1, HL2 and/or the inner lead IL2, so the relative position of the reference holes HLI, HL2 and the solid-state image sensor chip CHI is is set accurately. Therefore, the solid-state imaging device DV
When mounting S into an application product such as a VTR camera, if the reference holes HLI and HL2 are used as positioning standards, the center of the lens of the application product and the center of the photodiode array of the solid-state image sensor chip CHI can be aligned with high precision. can.

The recess IDX is a recess provided in the upper and lower ceramic bodies UPP and LOW, and is an index indicating the circuit arrangement reference position of the 20 outer leads ILL. This index IDX is used as a means to prevent incorrect connection when inserting the solid-state imaging device DvS (that is, the outer lead ILL) into the printed circuit board by placing pins that fit into the recesses of the index IDX on the printed circuit board side. is also helpful.

Next, a method for assembling the solid-state imaging device DVS will be briefly described.

First, the lead LD and the reference edible metal plate REFI.

A lead frame in which REF2 etc. are connected is formed from a single metal plate by press molding or etching. As a metal material, for example, 42 is compatible with ceramics.
70i is selected.

Next, a lead frame made by bending the outer lead OL at right angles is attached to the lower ceramic substrate LO, which has frit glass FLT coated in a frame shape on the high part around the mount part MNT.
W, sandwiched between upper ceramic frames UPP, and fused together using frit glass FLT.

Next, the solid-state image sensor chip CHI is automatically die-bonded to the mount portion MNT, and automatic wire bonding is performed between the inner lead IL and the solid-state image sensor chip CHI using a bonding wire WIR.

Next, the window glass GLS is attached to the upper ceramic frame Upp using an organic adhesive or the like.

Finally, cut off the unnecessary part of the lead frame LD and
Outer lead OL and reference edible metal plates REFI, RE
Separate each of F2. The convex portions BRD of the reference hole metal plates REFI and REF2 shown in the top view of (a) are the remains after removing unnecessary bridge portions.

FIG. 2(a) is a schematic sectional view of a solid-state image sensor chip CHI to which the present invention is applied, and FIG. 2(b) is a schematic cross-sectional view of a solid-state image sensor chip CHI to which the present invention is applied.
FIG. 2 is a partially enlarged schematic cross-sectional view.

In (a), ■ is a Si substrate, 2 is a photodiode section (light receiving section), 3 is an AQ light-shielding film, and 4 is a protective film made of SiL, PSG, PGMA, or the like.

5. 6, 7 are filter protective films made of PGMA etc., 8
is a first color filter, e.g., a red filter, 9 is a second color filter, e.g., a green filter, and 10 is a third color filter.
A colored filter, for example, a blue filter.

In (b), 11 is a Si film, and 12 is polycrystalline Si.
13.15 is a protective film made of PSG etc., 14 is AM
It is a wiring film.

As shown in these figures, light receiving filters 8, 9, and 10 of each color are formed on the photodiode 2.

FIG. 1(a) is a schematic top view of a solid-state image sensor chip CHI showing one embodiment of the present invention, and FIG.
It is a schematic sectional view taken along the bb cutting line of a).

In (a) and (b), 1 is a Si substrate, 2 is a light receiving part (
3 is an AQ light-shielding film, 16 is a bonding pad, 17 is an anti-reflection filter (indicated by diagonal lines)
Color filters 8.9.10 for light reception of the three primary colors of red, green, and blue are provided on the light receiving section 2, and the light receiving section 2 has the following characteristics:
The AQ light shielding film 3 is open. Light receiving color filter 8
．． AQ light shielding flI made of a material with high reflectance on the upper surface of the solid-state image sensor chip other than the light receiving section 2 provided with 9.10
3. The Si substrate 1 etc. is covered with an anti-reflection color filter 17 in which three layers of red, green and blue 377i (color filters 8, 9 and 10) are laminated.The color of the anti-reflection filter 17 is , red, green, and blue are mixed, so it is black.In this embodiment, most of the AQ and wiring 14 are AQ.
Since it is covered with the light shielding film 3, it hardly appears on the top surface of the chip. In addition, the pounding pad 16 is
Since the bonding wire is bonded, it is not covered with the anti-reflection filter 17 in this embodiment.

In this embodiment, the light incident on the light receiving section 2 is separated into lights by the red, green, and blue light receiving filters 8.9.10 as in the conventional manner. The anti-reflection filter 17 that covers the top surface of the chip other than the light receiving section 2 absorbs light of all wavelengths of the incident visible light. Therefore, due to the presence of this anti-reflection filter 17, reflected light due to light incident on the chip does not occur, so that generation of flare signals can be prevented.

It should be noted that the present invention is not limited to the above-mentioned embodiment, and it goes without saying that various changes can be made without departing from the gist of the invention.For example, in the above-mentioned embodiment, the Although the anti-reflection filter 17 was not formed on the bonding pad 16, the anti-reflection filter 17 was also formed on the bonding pad 16, and when the bonding wire was attached to the bonding pad 16, the anti-reflection filter 17 was formed only on the part where the bonding wire was connected. 17 may be removed by, for example, ultrasonic bonding.

In the above embodiment, one anti-reflection filter 17 is provided by laminating three color filters 8.9, 1o of red, green, and blue, but the anti-reflection effect can be obtained even if only one color filter is provided. Furthermore, in the above embodiment, the three color filters 8,9,10 are provided through the protective layer 5.6, but the three color filters 8,9,10 are provided on the same plane, and are used for antireflection. The filter 17 may be composed of one layer, and the filter 17 may be dyed using, for example, three colors of dyes to form a black filter. In this case, the filter portion can be thinned and flattened.

〔Effect of the invention〕

As explained above, according to the solid-state imaging device of the present invention,
Since the portions of the top surface of the solid-state image sensor chip other than the light-receiving portion made of a substance with high reflectance are covered with color filters, it is possible to prevent the generation of flare signals caused by reflections from these portions. Therefore, the signal-to-noise ratio S
/N is improved, and image quality can be improved.

[Brief explanation of drawings]

FIG. 1(a) is a schematic top view of a solid-state image sensor chip showing one embodiment of the present invention, FIG. 1(b) is a schematic cross-sectional view taken along the line bb in FIG. 1(a), FIG. 2(a) is a schematic cross-sectional view of a solid-state image sensor chip to which the present invention is applied, FIG. 2(b) is a partially enlarged schematic cross-sectional view of FIG. 2(,), and FIG. ) to (d) are diagrams showing the structure of a one-dimensional photosensor that is a solid-state imaging device to which the present invention is applied, and (a)
is a partially omitted cross-sectional view of the solid-state imaging device, (b) is a side view when viewed from above, (c) is a cross-sectional view taken along the Q-Q cutting line, and (d) is a partially omitted cross-sectional view when viewed from the right side. Cross-sectional view, (e
) is a partially omitted sectional view taken along section line 8-8. 1... Si substrate 2... Photodiode section (light receiving section) 3... AM light shielding film 4.5, 6.7.13.15... Protective film 8... First
Colored filter 9...Second color filter O...Third color filter...SiO□ film 2...Polycrystalline Si film 4...AΩ wiring film 6...Pon Ding pad 7...Anti-reflection filter 2------ Door/iode section (Mugiku 115) 3-
---Aj! Shinku film 9----1 second color-) Letter 10----131! , 0 fill 6 ----- Single insert 7-) F-tF'7 --- Anti-reflection filter Fig. 2

Claims (1)

[Claims] 1. A solid-state imaging device characterized in that the upper surface of the solid-state imaging device chip other than the light-receiving portion provided with the light-receiving color filter is covered with an anti-reflection color filter.