JPS58220578A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To improve the integration of an element, by providing an island area to a semiconductor area constituting a photodetection storing part, and by using it as a drain. CONSTITUTION:A photodetection storing part 41 consists of plural semiconductor areas 41a, 41b and so on arranged at intervals, and forms a p-n junction together with a substrate 40. Island areas 43a, 43b and so on of the same conductive type as that for the substrate 40 are provided in the semiconductor areas 41a, 41b and so on. If the island area 43 is used as a drain, a shift gate 45 is turned off before driving, and the voltage P3 is applied for the area 43 through a metallic layer 48. When light is irradiated through a window part 48', the potential P1 of the area 41 where a signal electric charge is stored lowers. If the potential P3 applied for the area 43 by the P1 lowers, the p-n junction between the area 41 and area 43 becomes the forward bias state, and an excess electric charge is discharged as an electric power source (i). The P1 never become smaller than the P3, and, therefore, the excess electric charge can be discharged through the area 43.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a solid-state imaging device, and particularly to a solid-state imaging device using an interline transfer method.

[Technical background of the invention]

Among solid-state imaging devices, the structure of a so-called interline transfer method is shown in FIGS. 1 and 2.

A light receiving and accumulating section 11 is formed on the semiconductor substrate 10 and is composed of a plurality of discrete semiconductor regions 11a, llb, llc, . . .
It forms a pn junction with 0 and accumulates signal charges obtained by external light irradiation. This signal charge is transferred to the charge transfer path 1 by a gate pulse applied to the shift gate 15.
The charge transfer path 12 is transferred to the semiconductor region forming the storage section 11, and
, llc.

Transfer electrodes 16 provided at intervals in response to...
By applying a predetermined clock pulse ξ to ξ, the signal charge is transferred to an output section (not shown) and extracted as an electrical signal.

Further, the P-rain 13 is provided to remove excess charges generated in the storage section 11 and to prevent these charges from adversely affecting the signal. For this purpose, a gate 7 is provided above the region 14 between the storage portion 11 and the drain 130, and, for example, potential peaks P14 and valleys P13 as shown in FIG. 3 are provided for each region of the conductivity type shown in FIG. By forming this, the excess electrons 18 in the storage portion are drawn toward the drain 13 side.

[Problems with background technology]

Shika, shika, that's it. In such a configuration, the skew 1, the ray 713 and the region 13 occupy a considerable area, which has been an obstacle to the integration of semiconductor devices.

[Purpose of the invention]

The present invention was made in order to eliminate the drawbacks of the prior art as described above, and an object of the present invention is to provide a solid-state imaging device with a novel configuration that can improve the degree of integration of elements.

[Summary of the invention]

In order to achieve this object, according to the present invention, a light-receiving device is formed on a semiconductor substrate to form a pn junction with the substrate, and is composed of a plurality of discrete semiconductor regions that accumulate signal charges obtained by external tS radiation. In a solid-state imaging device comprising a storage section and a charge transfer path formed on the substrate near the light receiving and accumulating section and serving as a semiconductor layer for extracting the signal charge, one semiconductor region of the light receiving and accumulating section is provided. The device has an island-like region having the same conductivity type as the substrate and to which a voltage can be applied from the outside.

More specifically, a voltage is applied to this island-like region to use it as a drain.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 4 and 5 show an interline transfer type solid-state imaging device according to an embodiment of the present invention, and are a top sectional view and a horizontal sectional view, respectively. According to the figure, a light receiving and accumulating section 41 and a charge transfer path 42 are formed on a semiconductor substrate 40, a shift gate 45 is provided between the two, and a charge transfer path 42 is provided.
2 is provided with a transfer electrode 46.

In the above configuration, according to the present invention, the light receiving and accumulating section 4
1 has a significantly different configuration. That is, the light receiving and accumulating section 41 includes a plurality of discrete semiconductor regions 41a.

41b, . . . form a pn junction together with the substrate 40, and generate and accumulate signal charges by externally irradiating light from above.

Moreover, according to this embodiment, in each of the semiconductor regions 41a, 41b, .
...is established. These island-like regions 43a and 43b
, . . . can be used as a drain as described later.

The surface of the semiconductor substrate 40 having each of these elements 41, 42, 43'i is covered with an insulating film 47, and a shift gate 45 and a transfer electrode 46 are buried in the insulating film 47. Further, above this insulating PS47, a shield metal layer 48 for insulating light is covered except for a window portion 48' for receiving light. At this time, a connection path 48g is provided in order to connect to the above-described island regions 43a, 43b, . . . using this shield metal.

Here, when using the island region 43 of a conductivity type solid-state imaging device as shown in FIG. 5 as a drain, it is driven as follows. Prior to driving, the shift gate 45 is turned off. Next, a voltage P3 is applied to the region 43 via the shield metal layer 48 as shown in FIG. By doing this, when light is irradiated through the light receiving window portion 48', signal charges photoelectrically converted in the region 41 are accumulated and transferred to the region 4.
1's potential P1 decreases. When the potential P1 of the region 41 becomes smaller than the potential P3 applied to the region 43 due to accumulation of charge, the pn junction between the region 41 and the region 43 becomes in an negative state one after another, and the excess charge flows out as a source 1. The potential P1 never becomes smaller than the potential P3, so that excess charges generated by the dangerous incident light can be discharged through the region 43.

In the above embodiment, the conductivity type is opposite to that shown in FIG.
3 in the area 41 is not particularly limited to the part shown in FIG.

〔Effect of the invention〕

As described above, this invention provides a solid-state imaging device with a novel configuration in which the degree of integration of elements can be improved by providing an island-like region in the semiconductor candy region forming the light receiving and accumulating section and utilizing this as a drain. can be provided.

[Brief explanation of the drawing]

Fig. 1 is a top sectional view of a conventional interline transfer type solid-state imaging device 1&', Fig. 2 is a cross-sectional view at xx'H of Fig. An explanatory diagram of the operation when a potential is applied, FIG. 4 is a top sectional view of the device according to the embodiment of the present invention, and FIG. 5 is YY'? f#
FIG. 6 is a cross-sectional view of the device shown in FIG. 40... Semiconductor substrate, 41... Light receiving and accumulating unit, 42...
... Charge transfer path, 43... Island-like region, 45... Shift gate, 46... Transfer amount, pole, 47... Insulating film,
48... Shield metal layer, 48'... Light receiving window portion. Applicant's agent Kiyoshi Inomata Figure 1 Dan v=, Figure 2 Iku J Figure 1 Day Market 4M 0 Townization Figure 5 Figure 6

Claims (1)

[Scope of Claims] 1. A light receiving and accumulating section formed on a semiconductor substrate and consisting of a plurality of discrete semiconductor regions that form a pi junction together with the substrate and accumulate signal charges obtained by external light irradiation; In the solid-state imaging device, the solid-state imaging device includes a charge transfer path, which is a semiconductor region formed on the substrate near the light receiving and accumulating section and for taking out the signal charge, in each semiconductor region of the light receiving and accumulating section. A solid-state imaging device comprising one island-like region of the same conductivity type and to which a voltage can be applied from the outside. 2. A solid-state imaging device according to claim 1, wherein a light shield metal covering the charge transfer path is electrically coupled to the island region to apply pressure to the cage. 3. A solid-state imaging device according to claim 1 or 2, wherein the island-like region functions as an r-rain for excess charge generated in the light receiving and accumulating section.