JPS6320865A - Solid-state image sensing device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of vertical transfer efficiency by projecting one conductivity type impurity region to the optoelectric transducer side more than an impurity region for forming a buried channel. CONSTITUTION:A high-concentration P-type region 22 is extended up to the N-type region 10 side of a photoelectric conversion section 4 to an N-type region 11 for a buried channel, thus obtaining potential having the flat bottom. Signal charges in a vertical CCD are transferred to a charge storage 5b from a charge storage section 5a through a path 6a and to a charge storage section 5c from the charge storage section 5b through a path 6b. Since there is no partial indentation of potential in the CCD in a process in which charges are transferred to the charge storage section 5c from the charge storage section 5b, charges can be transferred without deteriorating transfer efficiency. Since the indentation of potential is removed, the reduction effect of a smear generated by oblique incident beams can also be expected.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a solid-state imaging device, particularly a photoelectric conversion element and a vertical CC
The present invention relates to a CCD type solid-state imaging device composed of a D shift register and a horizontal CCD shift register.

(Prior Art) The optical conversion section and vertical COD shift register section in a conventional C, CD type solid-state imager are constructed as shown in FIG. In FIG. 2(a), la and lb are element isolation regions, 2a and 2b are first layer electrodes, 3a,
3b is a second layer electrode, 4 is a photoelectric conversion section, and 5a.

5b and 5c are charge storage sections of the vertical CCD shift register.

The direction of the optical signal flow is as follows. The optical signal charges generated and accumulated in the photoelectric conversion section 4 are as follows.

is transferred to the charge storage section 5b of the vertical COD through the path 7,
It sequentially moves toward the charge storage section 5c through the path 6b. However, the cross-sectional structure of a vertical CDD differs depending on the type of electrode. That's what I showed.

Figures 2(b) and 2(c). (b)-■ is a sectional view taken along the arrow 7 in FIG. 2(a), and (b)-■ is a potential diagram. (c)- is a sectional view taken along the arrow 8 in FIG. 2(a), and (C)-■ is a potential diagram.

9 is a P-type substrate, and 10 is an n-shaded area of the photoelectric conversion unit 4.

Reference numeral 11 denotes an n-shaded region which becomes a buried channel in the vertical CDD section, and 12 denotes a high-concentration P shadow region provided as a countermeasure against smear to prevent the depletion layer of the charge storage section from elongating.

18 is a high concentration P shadow area of the channel stopper.

(b) In the cross-sectional view of -〇, a signal charge is applied to the electrode 3a from the photoelectric conversion unit 4 by charge 7? The potential diagram after applying a high voltage for reading to the multiplication part 5b and then changing to a low voltage for charge transfer is shown in (b)-■. The potential 15 of the photoelectric conversion section is reset to the potential of the portion 14 when a high voltage is applied to the electrode 3a. Comparing the potential of the 13th part of the vertical COD with the potential of the other parts, the 13th part becomes deeper because there is no high-concentration P shadow region 12. Therefore, the signal charge falls as indicated by arrow 17. (
In the sectional view of the part e)-■, the P shadow area of the channel stopper protrudes due to the structure, so the vertical CCD n-type area
A high-density P shadow area exists below. Therefore, the potential becomes one without a dent like (C)-■.

(Problems to be Solved by the Invention) Looking at the signal flow in the conventional structure, when the signal moves from the charge storage section 5a to the charge storage section 5b, it passes through the path 6c, and the potential shown in (b) -■ get into the dent. Next, when transferring from the charge storage section 5b to 50, the path 6
d, but due to the dent in the potential, it becomes difficult to maintain a potential difference with the electrodes in the traveling direction, which causes a deterioration in transfer efficiency.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the conventional technology and to
An object of the present invention is to provide a solid-state imaging device that can prevent deterioration in transfer efficiency.

(Means for Solving the Problems) In the solid-state imaging device of the present invention, an impurity region of a conductivity type opposite to that of the buried channel impurity is located deep with respect to the buried channel impurity region of the vertical COD, and the photoconductive It extends to the converter side.

(Function) With the above configuration, on the photoelectric conversion section side, vertical COD
The dent in the potential is eliminated, and as a result, the signal charge is transferred smoothly.

(Example) An embodiment of the present invention will be described based on FIG.

In FIG. 1(a), Ia and lb are separation regions.

2a and 2b are, for example, first layer electrodes, and 3a, 3b are, for example, second layer electrodes. On the contrary, 2a, 2
b may be used as the second layer electrode, and 3a and 3b may be used as the first layer electrode.

As shown in FIG. 1(b)-■ (cross-sectional view along the arrow path 7), the high concentration P shadow area 22 is
By expanding the shaped area 11 to the n-shaded area 10 side of the photoelectric conversion unit 4, the potential is as shown in FIG. 1(b).
− As shown in ■, the bottom becomes flat. In addition, the cross section along the arrow path 8 is as shown in Fig. 1(C)-〇, and there is no difference from the conventional example, so the potential is also as shown in Fig. 1(c)-■. It is the same as.

The signal charges in the vertical CCD are sent from the charge storage section 5a to the charge storage section 5b through the path 6a, and further from the charge storage section 5b to the charge storage section 5c through the path 6b.

In the conventional example, there was a potential dent in the charge storage section 5b during the process of transferring the charge from the charge storage section 5b to the charge storage section 5c, which caused deterioration in transfer efficiency. Since there is no potential depression, charges can be transferred without deteriorating transfer efficiency.

Furthermore, by making a dent in the potential, it can be expected to reduce smear caused by obliquely incident light.

(Effects of the Invention) As explained above, according to the present invention, in the vertical COD potential, by eliminating the local potential depression at the signal readout section from the photoelectric conversion section, the vertical transfer efficiency is degraded. It has great practical effects, such as being able to prevent smear reduction and also being expected to have a smear reduction effect.

[Brief explanation of the drawing]

FIG. 1(a) is a plan view of one embodiment of the present invention, FIG.
b)-〇 and (C)-■ are sectional views, respectively, and Fig. 1(b)
)−〇 and (C)−■ are potential diagrams, respectively.
FIG. 2(a) is a plan view of the conventional example, and FIG. 2(b)-■. (c)-■ is the same cross-sectional view, Figure 2 (b)-■, (C)-
■ is a potential diagram. la, 11) =-separation area, 2a, 2b, 3a
, 3b... Electrode of vertical CCD, 4... Photoelectric conversion section, 5a, 5b, 5c... Charge storage section, 1
1... N-type region for CCD embedded channel, 18.
...High concentration P-type region for channel stopper, 22...
High concentration P shadow area. Patent Applicant: Matsushita Electronics Co., Ltd. 1st stage Ia, Ib...5 areas 2o, 2b, 3o, 3b...tTh4...L electric shock controller 5o, 5bt 5c...e CCD shift) Shi'y7-. 99t A i Loading and unloading Figure 1 1 11 ゛ CC0) t is also 9″ Daki W and punishment n A〉 to fishing ρ pa Jl thick exhibition P type @ rug 18 ・ !rqλ no entry, ha “Sweaty silk 5, Shou P
shape.俟し(Fig. 2

Claims (1)

[Claims] A group of photoelectric conversion elements and a vertical scanning C for reading and transferring optical signals from the group of photoelectric conversion elements are provided on a semiconductor substrate of one conductivity type.
A CD shift register group and a horizontal scanning CCD shift register group are integrated, and the one conductive type is formed under the impurity region of the opposite conductivity type to the one conductive type for forming the buried channel of the vertical scanning CCD shift register. 1. A solid-state imaging device, wherein an impurity region of one conductivity type is formed, and the impurity region of one conductivity type projects further toward the photoelectric conversion element than the impurity region for forming a buried channel.