JPH0376071B2 - - Google Patents

Description

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

[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 made up of a plurality of discrete semiconductor regions 11a, 11b, 11c, . The signal charge thus obtained is accumulated. This signal charge is transferred to the semiconductor region forming the charge transfer path 12 by a gate pulse applied to the shift gate 15.

The charge transfer path 12 connects each region 11a of the storage section 11,
By applying a predetermined clock pulse to transfer electrodes 16 provided at intervals corresponding to 11b, 11c, . . . , the signal charges are transferred to an output section (not shown).
and extract it as an electrical signal.

Further, the drain 13 is used to eliminate excess charges generated in the storage section 11 and to prevent these charges from adversely affecting signals. For this reason,
A gate 17 is provided on the region 14 between the storage portion 11 and the drain 13, and potential peaks P14 and valleys P13 as shown in FIG. 3 are formed for each region of the conductivity type shown in FIG. 2, for example. By doing so, the excess electrons 18 in the storage section are drawn toward the drain 13 side.

[Problems with background technology]

However, according to the above configuration, the drain 1
3 and 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 this invention,
A light receiving and accumulating section is formed on a semiconductor substrate and consists of a plurality of discrete semiconductor regions that accumulate signal charges obtained by external light irradiation, forming a pn junction with this substrate, and a light receiving and accumulating section in the vicinity of this light receiving and accumulating section. In a solid-state imaging device comprising a charge transfer path formed on the substrate and serving as a semiconductor region for extracting the signal charge, each semiconductor region of the light receiving and accumulating section has the same conductivity type as the substrate and is supplied with an external voltage. It is made to have an island-like area to which the voltage can be applied.

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

[Embodiments of the invention]

Embodiments of the present invention will be described below 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 transfer electrode 46 is provided in the charge transfer path 42. There is.

In the above configuration, according to the present invention, the configuration of the light receiving and accumulating section 41 is significantly different. That is, the light receiving and accumulating section 41 is made up of a plurality of discrete semiconductor regions 41a, 41b, . . . together with the substrate 40.
A pn junction is formed and signal charges are generated and accumulated by external light irradiation from above.

Moreover, according to this embodiment, in each of the semiconductor regions 41a, 41b, .
is provided. These island-like regions 43a, 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 is covered with an insulating film 47,
Further, a shift gate 45 and a transfer electrode 46 are buried in the insulating film 47. Furthermore, this insulating film 4
7 is covered with a shielding metal layer 48 for low light except for a window portion 48' for light reception. At this time, a connection path 48a is provided in order to connect to the above-described island regions 43a, 43b, . . . using this shield metal.

Here, when using the island-shaped region 43 of a conductive type fixed 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 potential P1 of region 41 becomes smaller than potential P3 applied to region 43 due to charge accumulation, the pn junction between region 41 and region 43 becomes forward biased, and excess charge flows out as power supply i. Potential P1 is never smaller than potential P3, so that excess charges generated by strong incident light can be drained away via region 43.

In the above embodiments, it goes without saying that the conductivity type may be opposite to that shown in FIG. It is not limited to.

〔Effect of the invention〕

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

[Brief explanation of drawings]

Figure 1 is a top sectional view of a conventional interline transfer type solid-state imaging device, Figure 2 is a cross-sectional view taken along line XX' in Figure 1, and Figure 3 shows the potential of the device in Figure 1 and therefore Figure 2. Explanatory diagram of operation when applying , 4th
The figure is a top sectional view of a device according to an embodiment of the present invention, FIG. 5 is a cross-sectional view taken along the YY' line of FIG. 4, and FIG. FIG. 40...Semiconductor substrate, 41...Light reception storage unit, 4
2...Charge transfer path, 43...Island region, 45...
Shift gate, 46... Transfer electrode, 47... Insulating film, 48... Shield metal layer, 48'... Light receiving window portion.

Claims (1)

[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 pn junction together with this substrate and accumulating signal charges obtained by external light irradiation, and the vicinity of this light receiving and accumulating section. A solid-state imaging device comprising a charge transfer path formed on the substrate and serving as a semiconductor region for extracting the signal charge, wherein each semiconductor region of the light receiving and accumulating section includes an island-like region of the same conductivity type as the substrate. What is claimed is: 1. A solid-state imaging device characterized in that a light shield metal covering the charge transfer path is electrically coupled to the island-shaped region, and a voltage is applied thereto.