JPS622651A - Solid state image pick-up device - Google Patents

Abstract

PURPOSE:To ensure electrical connection between a picture element electrode and a photoconducting film, by depositing a conductor film on an insulating film, which has a recess part or a protruded part between picture elements, and using the conductor film in the picture element part as a light shielding layer. CONSTITUTION:Before a conductor layer, which is to becomes a picture element electrode for defining a picture element, is formed, a recess part or a protruded part corresponding to the shape of the picture element 8 is formed in an insulating layer 14 of the surface layer of a solid scanning part by photoetching method and an anisotropic etching method. Then, the conductor layer, which is formed by sputtering evaporation and the like, is separated into a recess part electrode and a protruded part electrode by a step part formed by the anisotropic etching. After the evaporation of the conductor layer, a photoconducting layer can be continuously formed without taking out the device from a vacuum apparatus. Each electrode at the recess part or the protruded part between the picture element electrodes can be used as a light shielding electrode 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a solid-state imaging device that uses a photoconductive film as a photoelectric conversion section.

[Technical background of the invention and its problems]

CCD, CPD, MO with signal charge scanning function
A solid-state imaging device has been proposed in which a photoconductive film such as an amorphous Si film is laminated on top of a conventional solid-state imaging device such as S, and the photoconductive film is used as a photoelectric conversion section. A solid-state imaging device in which this photoconductive film is laminated has a high aperture ratio because almost the entire surface of the laminated light guide can be used for photoelectric conversion, reducing moiré and increasing sensitivity. Because it is a photoconductive film laminated on top, it is characterized by less smear and pluming than conventional solid-state imaging devices that perform photoelectric conversion using photodiodes formed on the bottom of the semiconductor substrate.

Figure 5 shows the photoconductive film described above. This is an example of a solid-state imaging device used as a converter, with CO in the signal scanning section.
FIG. 3 is a cross-sectional view of a pixel when D is used. Smear occurs when light leaking through the gap in the picture electrode (8) reaches the semiconductor substrate (1), so a light shield electrode (II) as shown in Figure 5 is necessary to keep the smear low. be.

However, in order for this light shield electrode αQ to sufficiently cover the gap between the pixel electrode (8), in addition to the width of the gap between the pixel electrodes (8), the alignment error between the pixel part α (8) and the light shield electrode u1 must also be considered. This light shield electrode a
1, the aperture ratio was greatly sacrificed.

In addition, in the conventional manufacturing method of depositing a conductor layer to become the pixel electrode (8) and then forming the electrode in a predetermined shape by photolithography, an oxide layer is formed on the surface of the pixel electrode (8). Then, a photoconductor B! is formed on the top of the pixel electrode (8). Xuυ
It is no longer possible to make a good electrical connection with the

For this reason, the material of the pixel electrode is restricted, and the manufacturing process is
L has become rough.

[Purpose of the invention]

An object of the present invention is to form a structure that reduces smear in a solid-state imaging device using a film as a photoelectric conversion part for light guide without reducing the aperture ratio of the entire photoelectric conversion part, and to provide an electrical connection between a pixel electrode and a photoconductive film. An object of the present invention is to provide a solid-state imaging device that can reliably perform close reading.

[Summary of the invention]

The present invention provides a CCD having a function of scanning signal charges,
Light guide 1 laminated on top of solid state scanning unit such as CPD, MOS! In a solid-state imaging device using d as a photoelectric conversion section, before forming a conductor layer that becomes a pixel electrode that defines a pixel, a recess or recess corresponding to the shape of the pixel electrode is photo-etched in the insulating layer on the surface of the solid-state scanning section. By forming the conductor layer by a method and anisotropic etching, the conductor layer, which is subsequently formed by sputter deposition, etc., is separated into an electrode in a concave part and an electrode in a convex part by a step formed by anisotropic etching. A photoconductive layer can be formed continuously without having to take out the conductive layer from the vacuum apparatus after being vapor-deposited, and the electrodes in the recesses or projections between the pixel electrodes can be used as they are as light shield electrodes. .

〔Effect of the invention〕

The effect of the present invention is that the formation process of the pixel electrode and the light shield electrode, which conventionally required two film formation processes and a photo-etching process, can be reduced to one photo-etching process and one film-forming process, thereby reducing manufacturing costs. It is possible to form a light shield electrode without sacrificing the aperture ratio, which lowers the moiré effect and increases sensitivity, suppressing smear. It is possible to form a photoconductive layer continuously within the photoconductive film, thereby preventing the surface of the pixel electrode from being contaminated or oxidized, and ensuring electrical connection between the pixel electrode and the photoconductive film.

[Embodiments of the invention]

According to Figures 1 to 4, CCDCD is used as a solid-state scanning section.
The present invention will be explained in detail by taking as an example the case where a photo-electro-membrane amorphous Si is used.

FIG. 1 is a cross-sectional view of a pixel of a solid-state imaging device related to the present invention, and shows a semiconductor substrate? l) COD channel (2) on top;
A gate insulating film (3), a transfer electrode (4) and a signal readout source (5) are formed, a first electrode (6) connected to the signal readout source part is formed, and a thick insulating layer is formed on these. The layer is flattened by an etch pack method etc. to form a smoothed insulating layer (with a force formed).
In order to suppress the occurrence of white scratches and increase in dark current due to unevenness of the substrate surface on which the 4' electrode i film is formed, the first electrode (
6) is adopted in order to reduce the height difference of the contact ball for connecting the pixel electrode (8) and the signal readout source section (5). From the state shown in FIG. 1, a contact hole connecting the first electrode and the pixel electrode is further formed with a tapered side surface, a photoresist pattern corresponding to the shape of the pixel electrode is formed, and this photoresist (9) is covered with a mask K.
Perform anisotropic etching using RIE etc. to smooth the insulating layer (
The state shown in FIG. 2 is a state in which a recessed portion is formed in the region between the pixels of the force. After this, when a conductor layer such as Mo, which will become a pixel electrode, is sputter-deposited, as shown in FIG. It is automatically separated into a shield electrode α1 that covers the gap between the electrode and the pixel electrode. Since both the pixel electrode (8) and the light shield electrode orJ are formed by vapor deposition alone, it is possible to proceed to the step of forming the photoconductive film immediately after vapor depositing the conductor layer.

Therefore, by combining the vacuum chamber of the film forming apparatus for forming the conductive film and the film forming apparatus for forming the photoconductive film, the conductive film and the photoconductive film can be continuously formed without exposing the semiconductor substrate to the air. By using a film-forming device that enables this, the surface of the conductive film will not be oxidized or contaminated, and the interface characteristics between the pixel electrode and the photoconductive film will be improved, ensuring electrical connection. It becomes like this.

FIG. 4 is a cross-sectional view of the photoconductive film UυKia in which the transparent electrode Iaα2 is also continuously formed, and shows the completed state of the cross-sectional structure of the pixel portion. In the above embodiment, the light shield electrode a1 is The same effect can be obtained by etching the portion where the pixel electrode (8) is to be formed to make it concave.

In addition, it is important to make the step separating the pixel electrode (8) and the light shield electrode 0C as small as possible so as not to increase white scratches or dark current. Therefore, the pixel electrode (8) should be made as thin as possible, and the contact hole should be made small. Pixel electrode (8) at the step of
The first electrode (6) and pixel electrode (8)
It is necessary to provide a sufficient taper on the side surface of the contact hole for connecting the pixel electrode (8).Also, it is also possible to select a metal for the pixel electrode (8) that reflects incident light sufficiently even if it is made thin. Important 0 In the above example, the contact hole was tapered, but when etch-packing the insulating layer (7), the insulating layer (force) and the electrode (6) were made to be on the same plane. It is also possible to eliminate the

[Brief explanation of the drawing]

1, 2, 3, and 4 are cross-sectional views showing the manufacturing process of a pixel of a solid-state imaging device according to an uninvented embodiment, and FIG. 5 is a sectional view of a pixel of a solid-state imaging device according to the prior art. FIG. 1... Semiconductor substrate 2... COD channel 3... Gate insulating film 4... Transfer electrode 5...
Signal readout source section 6...first electrode 7...smoothing insulating layer 8...pixel to pole 9...photoresist
10...Light shield electric kettle 11...Photoconductive film
12...Transparent single pole 13...Channel separation band 14.
...Excellent agent Patent attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 2

Claims (1)

[Claims] In a solid-state imaging device in which an insulating layer is provided on the surface of a scanning circuit board, a pixel electrode connected to the scanning circuit is provided on the surface of the insulating layer, and a photoelectric conversion layer and an electrode layer are laminated thereon, there is no recess or protrusion between the pixels. A conductive film is entirely deposited on the surface of the insulating layer having a part, the conductive film in the pixel part is used as the pixel electrode, and the conductive film in the concave or convex parts between the pixels is used as a light shield layer. solid-state imaging device.