JPS6051376A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To prevent the drop of light utilizing efficiency and to improve a blooming characteristic by etching the ground material of a gap part of an electric conductor electrode more widely than the gap of the electric conductor electrode, and providing a light shielding layer on its etched part. CONSTITUTION:When light is irradiated to a photoconductor film 58 in a state impressing a prescribed voltage to a surface electrode 60, it is photoelectrically transduced by the photoconductor film to generate a signal charge and also its signal charge passes through the first electrodes 40, 42, and is accumulated mainly in the first n<+> type impurity areas 4, 6 of a reverse-biased p type semiconductor substrate 2. The signal charge accumulated in this way passes through gate areas 8, 10 and is read out in the second n type impurity areas 12, 14 by impressing an voltage to gate electrodes 28, 30 and 32 after an optional accumulation time. A groove 44 of the gap part of the electric conductor electrodes 40, 42 is etched more widely than the gap of the electric conductor electrode, and a light shielding layer 46 is provided on that part not to expose the semiconductor substrate 2 against incident light 62, and to improve the blooming characteristic.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a solid substrate in which a photoconductive film is formed on a solid substrate on which a plurality of electrically independent electrodes are formed, and further electrodes are formed on the solid substrate. The present invention relates to an imaging device, and particularly to a solid-state imaging device with improved pluming characteristics.

[Technical background of the invention and its problems]

In order to increase photosensitivity, a solid-state imaging device (Japanese Unexamined Patent Publication No. 49-911
No. 16), solid-state imaging devices that combine a photoconductive film and a circuit with a self-scanning function (Japanese Patent Laid-Open No. 51-96720)
Publication No.) is known. Such solid-state imaging devices generally have unevenness on the scanning circuit board of about 1 to 2 μm, so if the photoconductive film is directly laminated, internal cranking or electrical leakage of the photoconductive film is likely to occur, resulting in image defects. Therefore, progress has been made in the direction of forming a scanning circuit by layering a photoconductive film after smoothing. For this reason, such solid-state imaging devices are characterized in that the electrodes that collect the charges photoelectrically converted by the photoconductor have a two-layer structure.

Generally speaking, solid-state imaging devices differ from image pickup tube targets in that the pixel regions are separated, so long-wavelength incident light that is not absorbed by the photoconductive film reaches the scanning substrate through the gap between the electrodes corresponding to the pixel. However, it is known to cause pluming. In order to suppress this blooming, the picture elements on the photoconductive film, however, in such a structure, the efficiency of using light incident on the photoconductive film decreases, resulting in a decrease in photosensitivity, and the incident light enters diagonally. When it comes to light, it has drawbacks such as almost no light transmission effect.

[Purpose of the invention]

The present invention was made in view of the above-mentioned drawbacks, and relates to a structure in which a light-transmitting part is placed near the two-layer electrode in a solid-state imaging device in which a photoconductive film is laminated on a smoothed scanning substrate. The purpose is to prevent a decrease in light utilization efficiency and improve blooming characteristics.

[Summary of the invention]

In the present invention, the base material in the gap between the conductor electrodes is etched to be wider than the gap between the conductor electrodes, and a light-transmitting layer is provided in the etched area. This blocks the incident light directed toward the semiconductor substrate from the isolation region of the electrode corresponding to the picture element, improving the blooming characteristic.

[Embodiments of the invention]

FIG. 1 is a sectional view of a solid-state imaging device according to an embodiment of the present invention, and FIG. 2 is a sectional view of a main part thereof.

The solid-state imaging device of the present invention is configured as shown in FIG. Gate region (8) adjacent to the first n+ type impurity region
, σC to the second n+ type impurity region Q,2,H
There are husbands and wives. Also number 1. a second n+ type impurity region (4), a p+ type stopper region (16) separating these units with (121,,) at position 111,
H, (20) is provided. Furthermore, on the substrate (2) where the gate region, the second n+ type impurity region, and the stopper region are located, a gate insulating film (22,
Polycrystalline silicon gate electrodes (a), po), (32), which are transfer electrodes, are provided through the gate electrodes (32).
4), an insulating film 04) is provided except for a part of (6), and on this insulating film (= is a contact hole (7)).

(2) through the first 11 type impurity region (4), (
6), and a plurality of independent first electrodes (41
. If the insulating film 04) is a SIO film, it is etched with ammonium fluoride.At this time, the first electrodes (4G, G) are etched by side etching.
It is etched wider than the gap Q. The degree of etching is preferably such that it does not affect the transfer electrode [30]. Next, a light-transmitting film 06) is formed at the bottom of the groove (44) formed by this etching.

The optically black light-transmitting film may be any material that prevents incident light, particularly long wavelength light, from reaching the semiconductor substrate (2).
For example, it is formed of a metal material such as Al, Cr, Ti, Mo, or W. The light-transmitting film is formed, for example, by vapor deposition,
A first electrode f40 (421) and a groove (44) are formed on the entire surface C2.

The shape of the groove (44) is as shown in FIG. 2 in the first electrode frame.

(By making the gap wider than the gap at the 4 sides, the groove (44)
The light-transmitting film and the first electrode f40, (4
Electrical connection with the light-transmitting film deposited on 3 is prevented.

Next, the semiconductor substrate formed as described above is covered with an insulating material as a smoothing layer (4 frames) to smooth the surface.

At this time, the groove is filled with an insulating material and smoothed. After this, a contact hole 5G (corresponding to the 4 grooves) is formed on the smoothing layer (4eJ), contact holes 5G (52) are formed on the 4eJ, and a conductive film is placed on the smoothing layer (4 wires) as the first electrode. (43, (4) is deposited so as to be connected to the conductive film. This conductive film is electrically connected to the first electrode via a light-transmitting film which is a conductive material.

This conductive film is separated into a first electrode (4S5) (a predetermined pattern corresponding to the four electrodes), and a second electrode (54).
, (56). The second electrode (54), (
A photoconductor film (58) and a surface electrode (60) are sequentially laminated on 56) and (57).

The photoconductor film (58) is made of, for example, amorphous silicon, and the surface electrode (60) is made of, for example, ITO.

In the solid-state imaging device described above, when light is irradiated onto the photoconductor film (58) with a predetermined voltage applied to the surface electrode (60), the photoconductor film performs photoelectric conversion and generates signal charges. At the same time, the signal charge is transferred to the first electrode (4n, +42
The first of the p-type semiconductor substrate (2) reverse biased through
It is mainly accumulated in the n+ type impurity regions (4) and (6). The signal charge accumulated in this way is transferred to the gate electrode /38), (30), C'+ after an arbitrary accumulation time.
By applying a voltage to the gate region (8),
(10) to the second n-type impurity region (12, (+
41.

Now, according to the solid-state imaging device of the present invention configured as described above, there is no part of the semiconductor substrate (2) that is exposed to the incident light (62), and there is no incident light to the substrate, and the pluming characteristics are improved. . Furthermore, the light utilization efficiency is not reduced by providing a light shielding film.

[Other embodiments of the invention]

In the above embodiment, an example was explained in which the insulating film <34) was side-etched, but it is also possible to form the groove by forming the conductive film that becomes the first electrode with a multilayer structure and etching the conductive film that becomes the lower layer. good. That is, metals with different etching rates are laminated in order from the one with the highest etching rate,
A groove wider than the gap between the first electrodes is formed by side etching the underlying conductor film, which has a low etching rate. As shown in this embodiment in FIG.
4) On top are a molybdenum layer (62) and an aluminum layer (
64) are sequentially stacked. Thereafter, by utilizing the side etching effect by plasma etching or the like, the aluminum layer (64) is separated into a predetermined pattern to form the first electrode, and the molybdenum layer (62) is side etched as shown in the third figure. Etching. After this, an aluminum layer (6
4) Deposit a light shielding film (4G) on top and on the insulating film (goods). Next, a smoothing layer (namely, a photoconductor film (58) and a surface electrode (60) are formed.

Furthermore, in this nine-layered structure, if the top layer is a conductor, the other layers may be insulators. In this case, if the insulator of the other layer is a material having a higher etching rate than the insulating film (3), the same effect as in the above embodiment can be expected.

Furthermore, in the present invention, the structure in which the light shielding film is provided may be provided on the smoothing layer (on the second electrode side provided on the bridge), or may be applied to both the first and second electrodes.

In the above-described embodiments, a CCD is used as a scanning circuit formed on a semiconductor substrate, but the present invention is not limited to these, but can also be applied to a MOS type, CHD+BBT).

〔Effect of the invention〕

As explained above, according to the present invention, even if the first electrode and the second electrode are provided in a matrix, the semiconductor substrate is shielded from incident light by the light shielding film.
Plumping characteristics are improved compared to conventional methods.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
Enlarged view of the main parts of the solid-state imaging device shown in Figure 1, Patent Attorney Kensuke Chika (and one other person), Figure 1, Figure 2

Claims (1)

[Claims] A semiconductor substrate having a scanning circuit and a plurality of charge storage parts, a conductor electrode electrically connected to the storage part and separated from each other correspondingly, a photoconductor film, and a photoconductor film on the photoconductor film. In the solid-state imaging device having a surface electrode provided therein, an insulating film is provided between the gap portion of the conductor electrode and the semiconductor substrate, the insulating film is etched to be wider in the gap portion than the gap, and A solid-state imaging device comprising a light shielding layer in an etched portion.