JPS6195680A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To reduce smears of a two-dimensional solid-state image pickup device by constituting said device of plural photoelectric conversion parts formed on a semiconductor substrate and a scan circuit and constituting an inter-layer insulating film except the photoelectric conversion parts of a high-resistance light shielding member. CONSTITUTION:Photodiode 2, a gate channel part 3 of a read MOS, a transfer channel 4 of a CCD, a gate oxide film 5, a PolySi electrode 6 for servicing as the read gate of the read MOS and the transfer gate of the CCD, a field oxide film 7 and a channel stopper 8 are formed on the semiconductor substrate 1. Moreover, an inter-layer insulating film 19 of low transmissivity, which employs a-Si or other photoelectric target member of an image pickup tube, and a light shielding metallic film 10 on the transfer channel of the CCD are formed. Direct entry of a strong incident light 11 on the transfer channel to the transfer channel is inhibited by the light shielding metallic layer 10. On the other hand, an incident light 13 passing through an opening 12 on the photodiode 2 reduces entry light up to adjacent picture element parts due to the existence of the film 19.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a two-dimensional solid-state imaging device, and relates to a solid-state imaging device having a novel structure for eliminating the adverse effects of strong incident light on the screen.

Conventional configurations and their problems In general, in two-dimensional solid-state imaging devices, when strong signal light is incident on the imaging surface where the scanning circuit perpendicular to the light receiving section is formed, the strong incident light causes a signal to be generated within the semiconductor substrate. False signal charges enter the vertical scanning circuit. As a result, a phenomenon called smear, in which thin vertical stripes are drawn, appears on the image capture screen. This is a major problem with solid-state imaging devices.

FIG. 1 is a cross-sectional view showing an example of a unit pixel of an imaging section of a two-dimensional solid-state imaging device using an Sl pn junction as a light receiving section and an embedded COD as a scanning circuit.

Here, 1 is a semiconductor substrate, 2 is an impurity diffusion layer of a conductivity type opposite to that of the semiconductor substrate) f) diode, 3
M reads the signal charge of photodiode 2 into COD
O3) Gate channel part of transistor, 4 is embedded C
Transfer channel part of OD, 5 is gate oxide film, 6 is PolySi electrode which serves as read gate of read MO8 transistor and transfer gate of COD, 7 is field oxide film, 8 is channel stopper, 9 is PSG, BS
G.

An interlayer insulating film made of NSG or the like, 1o, is an insulating film 1o that blocks light from directly entering the transfer channel of the COD.

It is a metal such as MO.

Here, when strong light hν is incident on the imaging surface, the incident light 11 on the transfer channel is prevented from entering the transfer channel by the light shielding metal 10, but the incident light through the aperture 12 on the photodiode is 13 directly enters the adjacent transfer channel while interfering between the photodiode and the light shielding metal through the transparent glabella insulating film 9, or enters the semiconductor substrate under the field oxide film at the boundary with the adjacent pixel. The incident electrons generate electron-hole pairs, and the electrons at this time invade adjacent transfer channels and become a cause of smear generation as false signal charges. This smear has a serious adverse effect on the characteristics of the imaging screen and must be reduced as much as possible.

Purpose of the Invention In view of these conventional problems, the present invention aims to provide a two-dimensional solid-state imaging device with a novel structure that reduces smear in the two-dimensional solid-state imaging device and thereby improves the characteristics of the imaging screen. It is something.

Structure of the Invention The present invention uses a material with significantly low transmittance to light as the glabellar insulating film on the transfer channel. This from K.
Intense light incident through the aperture on the photodiode is attenuated from entering the adjacent transfer channel due to interference.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention is shown in FIG. Here, 1 is the semiconductor substrate, 2 is the photodiode, 3 is the gate channel part of the read MoS transistor, 4 is the transfer channel of the COD, 6 is the gate oxide film, e is the read MOS) transistor read gate and the COD transfer gate Po1 also serves as
y Si electrode, 7 is a field oxide film, 8 is a channel
Stopper.

19 is an interlayer insulating film with low transmittance to light, a-8i
(Amorphous silicon) or other light guide target materials for image pickup tubes (Ubicon film, Sachicon film, etc.) are used. 1o
is a light-shielding metal film on the transfer channel of the COD. Here, the strong incident light 11 on the transfer channel is reflected by the light shielding metal 1o
This prevents direct intrusion into the transfer channel. on the other hand,
Incident light 13 passing through the aperture 12 on the photodiode 2
Due to the presence of the glabella insulating film 19 with low transmittance, interference between the substrate side and the shielding metal 1o side is attenuated, and unlike the conventional example, the amount of light penetrating into the adjacent pixel portion is significantly reduced. For this reason,
When compared with the conventional example, the smear signal charges that invade into adjacent transfer channels due to the interference of strong incident light within the interlayer dielectric film are significantly reduced.

Effect of the invention A scanned image of a two-dimensional solid-state imaging device according to the present invention.

By using a material with extremely low light transmittance for the glabellar insulating film between the path and the light shielding metal film on the scanning circuit, when strong light enters, it will not interfere between the substrate side and the light shielding metal. This glabellar insulating film with low transmittance can block light from entering the scanning circuit side. Therefore, the smear caused by the false signal charge that conventionally occurs due to the wraparound light due to such interference can be significantly improved.

By the way, a-
When a 5i film or the like is used, due to its low transmittance to visible light, it is possible to improve the smear suppression rate by more than 10 times compared to the conventional 8102 oxide film-based transparent interlayer insulating film.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional structural diagram of a unit pixel portion of a general two-dimensional solid-state imaging device showing a conventional example, and FIG. 2 is a cross-sectional structural diagram showing a unit pixel portion of the same device according to an embodiment of the present invention. 1...Semiconductor substrate, 2...Photodiode, 3...QCD transfer channel node 6...
...Transfer Po1y Si electrode, 1o...Light shielding metal film, 19...1. Opaque interlayer dielectric film.

Claims (1)

[Claims] 1. A solid-state imaging device comprising a plurality of photoelectric conversion sections and a scanning circuit formed on a semiconductor substrate, wherein an interlayer insulating film in a portion other than the photoelectric conversion sections is made of a high-resistance light shielding material.