JPS63226959A - Solid-state image sensing device - Google Patents

Abstract

PURPOSE:To obtain a device which prevents a false signal such as a ghost or a flare from occurring and is suitable for high-density integration by a method wherein a false-signal preventive film composed of a resin film dyed by using a dyestuff capable of absorbing the light of a prescribed wavelength range is formed at a signal readout part. CONSTITUTION:At a solid-state image sensing device where a photoelectric conversion part including a group of photoelectric conversion elements and a signal readout part to read out a signal charge from individual photoelectric conversion elements are installed on an identical semiconductor substrate 6, a false-signal preventive film 16 composed of a resin film dyed by a dyestuff capable of absorbing a prescribed wavelength range is formed at said signal readout part. For example, a flattening film 15 composed of a phospho-silicate glass film, a silicon oxide film, a transparent resin film or the like is installed on the main face of a CCD image sensor of an interline transfer system. A resin film 16 which is dyed by a dyestuff capable of absorbing, at least, the visible light of wavelengths ranging from 350-750 nm is installed on a flattening film 15 situated on a transfer electrode 9 and a metal light-shielding film 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a solid-state imaging device, and more particularly to a solid-state imaging device that prevents reflection from a wiring metal film forming the solid-state imaging device.

[Conventional technology]

2. Description of the Related Art Conventionally, a solid-state imaging device includes a photoelectric conversion section and a signal readout section shielded from light by a metal film such as an aluminum film, formed on the main surface of a semiconductor substrate. This metal light-shielding film is a means for preventing direct light from entering the signal reading section and generating false signals.

However, when strong light is incident, the light reflected by this metal light-shielding film is reflected again on the imaging device's cap glass or lens surface and enters the solid-state imaging device, causing image damage such as ghosts and flare, and false signals. cannot sufficiently prevent the occurrence of

FIG. 2 is a plan view ttg of an interline transfer type COD image sensor, which is a conventional solid-state imaging device. For convenience, the figure shows 3×3 picture elements (picture elements).
ture element)) is shown. In the figure, 1 is a light-receiving surface of a photoelectric conversion element such as a photodiode, 2 is a vertical CCD register constituting a signal readout section for reading out a photoelectrically converted signal, and 3
Similarly, 4 is a horizontal COD register, 4 is an output circuit, and 5 is an output terminal. Since the interline transfer type COD image sensor is well known, the details of its operation will not be explained.

FIG. 3 is a sectional view of the semiconductor chip of the COD image sensor shown in FIG. 1. In addition, in the same figure, for convenience of explanation,
It is only a conceptual diagram and does not correspond dimensionally to an actual device.

In FIG. 3, 6 is a p-type semiconductor substrate made of silicon, for example, and 7 is an element region of a photodiode, which is an n-type diffusion layer and forms a p-n junction with the p-type semiconductor substrate 6. In FIG. Reference numeral 8 denotes a transfer channel portion of the vertical COD register, which is usually made of a layer of a conductivity type opposite to that of the semiconductor substrate. 9 is a vertical C formed through an insulating layer film 10 such as 5i02.
This is a CD transfer electrode. Further, the transfer channel section 8 of the vertical CCD register and the element region 7 of the photodiode are electrically separated by a channel stopper 11. Reference numeral 12 denotes a metal light-shielding film made of a metal such as aluminum, which is provided to prevent direct light from entering the transfer channel portion 8 of the vertical COD register from which signals are read. In such an interline transfer type CCD image sensor, as mentioned above, in the part where the vertical COD register part, which is the signal readout part, is light-shielded, light similar to the light 13 incident on the photodiode is reflected by the metal light-shielding film 12, and scattered light is generated. As 14, it causes ghosts and flares. As a means to solve these drawbacks, a frame transfer type CD image sensor in which a photoelectric conversion section and a signal readout section are separated has been announced.

However, this frame transfer type CCD image sensor has a larger chip size and is less flexible.

This is not necessarily effective in practice as a ghost prevention measure.

[Problem that the invention seeks to solve]

As described above, the conventional interline transfer type CCD image sensor has the drawback that false signals are generated due to reflection from a metal light-shielding film. Furthermore, the CD image sensor using the frame transfer method has the disadvantage that it is not suitable for high-density integration.

An object of the present invention is to provide a solid-state imaging device that is suitable for high-density integration and prevents the generation of false signals such as ghosts and flares.

[Means for solving problems]

A solid-state imaging device of the present invention is a solid-state imaging device in which a photoelectric conversion section including a group of photoelectric conversion elements and a signal readout section for reading signal charges from each of the photoelectric conversion elements are provided on the same semiconductor substrate. A false signal prevention film made of a resin film dyed with a dye that absorbs light in a wavelength range is formed in the signal readout section.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a semiconductor chip showing one embodiment of the present invention.

6 is a p-type semiconductor substrate made of, for example, silicon; 7 is an n-type diffusion region selectively formed in the element region of the photodiode, forming a p-n junction with the p-type semiconductor substrate 6; Reference numeral 8 denotes a transfer channel of a vertical COD register, which is a signal readout section, and is usually made of an n-type diffusion layer. That is, the signal readout section is composed of a buried channel type COD. 9 is a transfer electrode formed on the transfer channel via an insulating film 10 such as 5i02. Reference numeral 11 denotes a channel stopper, which is composed of a p+ type region having the same conductivity type as the p type semiconductor substrate 6 and having a high impurity concentration. Reference numeral 12 denotes a metal light-shielding film made of a metal film such as aluminum 4, which is a wiring metal, to prevent light from entering the signal readout section.

The above configuration and operation are completely similar to the conventional example shown in FIG. 2.

The first difference between this embodiment and the conventional one is that, for example, a phosphor glass film or a silicon oxide film formed by bias sputtering is provided on the main surface of a conventional interline transfer type CCD image sensor for flattening. , it has a flattened WA 15 made of a silica film or a transparent resin film such as polymethacrylic acid cridine (PGMA). Although this flattening film 15 is not necessarily a necessary component for the present invention, it is convenient to form this flattening film as a pre-process for taking the next antireflection measure.

The second point is that the dyed resin film 16 is provided on the transfer electrode 9.

To form this dyed resin film, a dyeable resin layer made of gelatin, casein, pullulan, polyvinyl alcohol, etc. mixed with a photosensitizer (for example, potassium dichromate) is applied onto the flattened film 15 using a spin code method. Thereafter, the dyeable resin layer is selectively removed by photolithography so as to cover the metal light shielding film 12.The remaining dyeable resin layer covers the light-receiving surface and scribe area shown in FIG. and is formed so as to remain on the entire surface of the semiconductor chip of the solid-state imaging device except for the bonding region.
The resin layer is dyed by immersing the semiconductor chip in an aqueous solution of an acidic dye, cationic dye, etc. that absorbs nm visible light, and a dyed resin film 16 is formed.

In this configuration, the entire area other than the light-receiving surface 1 of the photodiode is covered with a black-dyed resin film, so the generation of false signals such as ghosts and flares due to metal shielding 71!12, which has been a problem in the past, is completely eliminated. It can be eliminated.

Since the embodiment described above is a solid-state imaging device for visible light, it is dyed black, but since it is sufficient to absorb light at the wavelength to which the solid-state imaging device is sensitive, it may not necessarily be dyed black depending on the spectral sensitivity characteristics. You don't have to.

〔Effect of the invention〕

As explained above, the present invention eliminates ghosts, flares, etc. by covering areas other than the photoelectric conversion element area of a solid-state imaging device, especially the signal readout area, with a resin film dyed with a dye that absorbs light in a predetermined wavelength range. This has the effect of preventing false signals.

Further, although the present invention has been described using an interline transfer type COD image sensor as an example, it goes without saying that the present invention can be applied to all solid-state imaging devices such as an MO8 type image sensor.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a semiconductor chip showing an embodiment of the present invention, FIG. 2 is a plan layout diagram of a conventional interline transfer type CCD imaging device, and FIG. 3 shows the conventional example shown in FIG. 2. FIG. 2 is a cross-sectional view of a semiconductor chip. 1... Light receiving surface, 2... Vertical CCD register, 3...
・Mizuko〇CD register, 4... Output circuit, 5... Output terminal, 6... P-type semiconductor substrate, 7... Photodiode element region, 8... Transfer channel, 9... Transfer electrode, 10... Insulating film, 11... Channel stopper, 12... Metal light shielding film, 13... Incident light, 14...
- Reflected light, 15... Flattening film, 16... Dyed resin film. Agent Patent Attorney Uchihara Oto No. 30

Claims (1)

[Claims] A dye that absorbs light in a predetermined wavelength range in a solid-state imaging device in which a photoelectric conversion unit including a group of photoelectric conversion elements and a signal readout unit that reads signal charges from each of the photoelectric conversion elements are provided on the same semiconductor substrate. A solid-state imaging device, characterized in that a false signal prevention film made of a resin film dyed with is formed in the signal readout section.