JPS6410984B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a charge coupled device (CCD) type solid-state imaging device.

In recent years, this type of solid-state imaging device for use in television cameras has been actively developed, and the applicant has already proposed a cross-gate type solid-state imaging device in Japanese Patent Application No. 84267-1983. are doing.

FIG. 1a shows a plan view of a conventional cross-gate solid-state imaging device, and FIG. 1b shows a cross-sectional view taken along line A--A in FIG. 1a. As shown in these figures, in the conventional element, a plurality of upper layer electrodes 3 and a plurality of lower layer electrodes 4 are orthogonally arranged on a P-type semiconductor substrate 1 in an insulated state with a transparent insulating film 2 interposed therebetween. The gap surrounded by these upper and lower layer electrodes 3, 4, . Then, on this semiconductor substrate 1,
In this case, channel stoppers 12 with a higher impurity concentration than the substrate 1 are formed along the upper layer electrodes 3, and the width of each stopper 12 increases at every other point where it contacts the light receiving section 11. As a result, unevenness is formed that is complementary to the adjacent channel stoppers 12. Furthermore, each of the above-mentioned electrodes 3 remaining between the channel stoppers 12...
. . , 4 . . . One location of the lower P-type semiconductor substrate forms a channel 13 . . . , and each of these channels 13 .

In a solid-state image sensor having such a configuration, when the lower electrodes 4' in odd-numbered rows are turned on, the charge corresponding to the amount of incident light generated in the light receiving section 11 is generated as shown by the solid line arrow in FIG. The light is introduced from the light receiving sections 11, 11, . After that, the upper layer electrodes 3'' of the even number rows and the lower layer electrodes 4'' of the even number rows, and then the upper layer electrodes 3' of the odd number rows and the lower layer electrodes 4' of the odd number rows are alternately switched to the ON state. Therefore, the above charge is transferred in a meandering manner from channel 13 position ○A to ○I, ○U, ○E, ○O,...
The output terminal (not shown) of such an element is outputted to the outside as an image signal.

The conventional solid-state image sensor as described above has a light receiving section 11.
Since there are no electrodes, it has the advantage of being able to directly receive incident light without attenuating it, but the potential of this light receiving section 11 cannot be controlled, and the surrounding electrodes 3
..., 4..., the light receiving section 11
The drawback was that the potential was extremely unstable. That is, for example, when the charge being transferred to the channel 13 position ○U is about to be transferred to the next position ○E, ○O, the unstable potential formed in the light receiving part 11 of the same conductivity type as the channel 13 As a result, the light receiving section 11 would become a channel, and there was a risk that the transferred charge would bypass the light receiving section 11 and flow back to position ○A, as shown by the broken line arrow in FIG.

The present invention has been made in view of these points,
An object of the present invention is to provide a cross-gate type solid-state image sensor in which a light receiving section is not channelized during charge transfer.

FIG. 2a shows a plan view of the solid-state imaging device of the present invention, and FIG. 2b shows a sectional view taken along the line A'-A'.

In these figures, 1, 2, 3, and 4 are a P-type semiconductor substrate, an insulating film, an upper layer electrode,
A lower layer electrode is shown, and high concentration P ⁺ type channel stoppers 12 . . . and P type channels 13 . . . are formed on this semiconductor substrate 1 as in the conventional device. The solid-state imaging device according to the embodiment of the present invention differs from the conventional device in that a channel 13, that is, a light-receiving portion 14 having a higher impurity concentration than the substrate 1 is formed. That is, a high concentration P ⁺ type light receiving section 14 is formed in contact with the upper layer and lower layer electrodes 3..., 4... and the P type channel 13... provided in a meandering manner below, and this light receiving section 14... The point is that the charge, in this case the potential for electrons, is set smaller than that in channels 13...

An example of such a device of the present invention will be explained by citing specific numerical values. Specific resistance 10~20Ωcm as semiconductor substrate 1
The channel stopper 12 is made of P type silicon with a high concentration of P ⁺ type, and boron is applied to the substrate 1 at 80 KeV.
The ions were implanted at a concentration of 2×10 ¹⁶ /cm ³ . After that, the surface of the substrate 1 is thermally oxidized to form a transparent insulating film 2 made of silicon dioxide with a thickness of 1400 Å, and boron is further applied on top of it at a voltage of 80 KeV.
ion implantation with higher concentration than channel 13.
A P ⁺ type light receiving section 11 is formed.

According to the configuration of the present invention, the P ⁺ type light receiving section 14
The charges generated according to the amount of incident light, in this case electrons, are located at the channel 12 position ○A under the lower electrode 4' of the odd row where a positive voltage is applied and is in the ON state, as shown by the solid line arrow in Figure 2. can be stored in Thereafter, by sequentially applying a positive voltage to each electrode 3..., 4..., electrons will be transferred to channel 13 positions ○I, ○U, ○E, ○O, etc., but at this time, Light receiving section 14...
is a P ⁺ type region, unlike the P type channels 13..., so the potentials formed in the light receiving parts 14... under the influence of the positive voltages applied to the respective electrodes 3..., 4... are the channels 13... can be made sufficiently smaller than the potential formed in Therefore, the electrons being transferred in the P-type channel 13 are
There is no risk that the light will bypass the P ⁺ type light receiving section 14 and flow backward.

In the above embodiment, the P-type semiconductor substrate 1 was used as it was as the channel 13, but as shown in the cross-sectional view of FIG. channel 15
Even in the case of a solid-state image sensing device formed with
With this, there is no risk that an unstable potential for transfer charges, in this case electrons, will be formed in the light receiving section 16, as in the example element shown in FIG. Therefore, the light receiving section 16 is prevented from becoming a channel during charge transfer.

As is clear from the above description, the solid-state imaging device of the present invention is a cross-gate type device, and the light-receiving portion provided in contact with the meandering channel is composed of an impurity region in which it is difficult to form a potential compared to the channel. Therefore, there is no risk that the light receiving section will form an unnecessary potential due to the influence of the voltage applied to the potential control electrode of the channel, and thereby the transfer charge generated in conventional elements can be reduced. Accidents such as backflow of water can be prevented. Therefore, a high-quality image signal free from noise caused by backflow charges can be obtained.

[Brief explanation of drawings]

1A and 1B are a plan view and a sectional view thereof of a conventional solid-state image sensor, FIGS. 2A and 2B are a plan view and a sectional view thereof of an embodiment of the solid-state image sensor of the present invention, and FIG. FIG. 7 is a cross-sectional view of another embodiment of the inventive element. DESCRIPTION OF SYMBOLS 1... Semiconductor substrate, 2... Insulating film, 3... Upper layer electrode, 4... Lower layer electrode, 11, 14, 16... Light receiving section, 12... Channel stopper, 13, 15
...Channel.

Claims (1)

[Claims] 1. A semiconductor substrate, an insulating film formed on the semiconductor substrate, a plurality of lower layer electrodes arranged in parallel on the insulating film, and an arrangement direction of the lower layer electrodes provided insulated on the lower layer electrode. a plurality of upper layer electrodes arranged in a direction intersecting with the upper layer electrodes, a gap surrounded by the two electrodes is used as a light entrance window to constitute a light receiving section, and a meandering channel for charge transfer is provided adjacent to the light receiving section. In the solid-state imaging device equipped with the above-mentioned solid-state image sensor, when the conductivity type or impurity concentration of the semiconductor portion of the light receiving section is made different from that of the channel, and a positive voltage for charge transfer is applied to each electrode, the channel under the electrode is A solid-state imaging device characterized in that the potential of the semiconductor portion of the light receiving portion is set to be smaller than the potential of the semiconductor portion of the light receiving portion.