JPH05291551A - Solid-state image sensing device - Google Patents

Abstract

PURPOSE:To provide a solid-state image sensing device which can reduce a chip size without lowering performance by using a null region effectively below a gate electrode. CONSTITUTION:In a solid-state image sensing device wherein a P<->-type well 12 is formed on an N-type substrate 11 and which has a photoelectric conversion part 101 including a photoelectric conversion N<->-type layer 13 formed on the P<->-type well 12 and a charge transfer part 100 which is formed next to the photoelectric conversion part 101 and includes a charge transfer N<->-type layer 17 formed on the P<->-type well 12 and a gate electrode 19 formed on the charge transfer N<->-type layer 17 with a gate insulating film 18 between, the photoelectric conversion N<->-type layer 13 includes an extension part 13a which extends toward the charge transfer N<->-type layer 17 below the gate electrode 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device,
More specifically, the present invention relates to an interline transfer CCD (charge transfer device) type solid-state imaging device.

[0002]

2. Description of the Related Art Generally, this kind of interline transfer C
As shown in FIG. 2, the CD-type solid-state imaging device has a low impurity concentration P ⁻ type well 22 formed on an N type semiconductor substrate 21, and a low impurity concentration photoelectric conversion on the P ⁻ type well 22. A plurality of photoelectric conversion units 201 including the N ⁻ type layer 23 are provided at equal intervals in the lateral direction.

Further, a pixel separation region 2 composed of a P ⁺ type layer
A charge transfer unit 200 is provided adjacent to each of the photoelectric conversion units 201 with 5 interposed therebetween. Each charge transfer unit 200 has N
^- it is composed of a transfer channel 27 and the gate insulating film 28 and the gate electrode 29 of the mold.

Further, 24 and 26 are P-type impurity layers, and 26 can be omitted. The pixel separation areas 25 and 2
One pair of photoelectric conversion unit 201 and charge transfer unit 200 sandwiched by 5
And each form one column.

The photoelectric conversion units 201 in each of the columns convert incident light into signal charges, and the signal charges are transferred to the charge transfer units 2 in the columns.
00 transfers.

[0006]

By the way, in the recent solid-state image pickup devices, the size of the lens used is from 1/2 inch to 1 inch.
The size of the semiconductor substrate 21 tends to be reduced to ⅓ inch, and further to ¼ inch.
It is desired to reduce (chip size). However, reducing the sizes of the transfer unit 200 and the photoelectric conversion unit 201 reduces the maximum signal charge amount, sensitivity, etc.
It is not preferable because it causes performance deterioration. Therefore, in order to reduce the chip size without degrading the performance, it is necessary to effectively use the ineffective regions A and B below the gate electrode 29 shown in FIG.

Therefore, an object of the present invention is to provide a solid-state image pickup device capable of reducing the chip size without lowering the performance by effectively utilizing the ineffective region below the gate electrode.

[0008]

In order to achieve the above object, the present invention provides a photoelectric conversion section including an N-type layer for photoelectric conversion formed on a P-type well formed on an N-type substrate, and A charge including an N-type layer for charge transfer formed on the P-type well formed in parallel with the photoelectric conversion unit, and a gate electrode formed on the N-type layer for charge transfer via a gate insulating film. In the solid-state imaging device having a transfer part, the photoelectric conversion N-type layer includes an extension part extending below the gate electrode toward the charge transfer N-type layer.

[0009]

According to the above structure, the region, which is a conventional ineffective region, below the gate electrode can be effectively used as an extension of the photoelectric conversion N-type layer, and the photodiode capacitance is improved.
It is possible to prevent the generation of smear components due to obliquely incident light, improve sensitivity, and reduce the chip size without degrading performance.

[0010]

The present invention will be described in detail below with reference to the embodiments shown in the drawings.

FIG. 1 shows an embodiment of the solid-state image pickup device of the present invention.

The manufacturing process of the embodiment shown in FIG. 1 will be described.
First, a P ⁻ type well 12 having a low impurity concentration is formed in an upper layer including the upper surface 11 a of the N type semiconductor substrate 11. Then, the P ^-
N for forming the photoelectric conversion portion 101 in the mold well 12
^- type impurity layer 13 above P ^- the upper layer of the type well 12 the whole surface
It is formed on the entire effective pixel area. After that, a P ⁺ -type impurity is implanted to form a P ⁺ -type impurity layer 14 to form a photoelectric conversion N forming the photoelectric conversion unit 101.
The mold layer 13 is separated at equal intervals. Further, a pixel isolation region 15 which is a channel stop portion formed of a P ⁺ type layer, a transfer channel 17 formed of an N ⁻ type layer, and a transfer gate portion which transfers charges generated in the photoelectric conversion portion 101 to the charge transfer portion 100 are formed. ^The -type layer 20, the gate insulating film 18, and the gate electrode 19 are formed.

In the solid-state image pickup device, the N ^-- type impurity layer 13 constitutes the photoelectric conversion portion 101, and the gate electrode 19 is formed.
The gate insulating film 18 and the transfer channel 17 constitute the charge transfer section 100. In addition, the N ⁻ type impurity layer 1
3 is the transfer channel 1 below the gate electrode 19.
7 includes an extension 13a extending toward 7.

Each pair of the photoelectric conversion section 101 and the charge transfer section 100 sandwiched by the pixel separation regions 15 and 15 is one.
It consists of two columns.

The photoelectric conversion units 101 in each column convert incident light into signal charges, and the signal charges are transferred to the charge transfer units 1 in the columns.
00 transfers.

According to the above-mentioned structure, the region below the gate electrode 19 which is a conventional ineffective region can be effectively used as the extension 13a of the photoelectric conversion N-type layer 13 to improve the photodiode capacitance and oblique incidence. The generation of smear components due to light can be prevented, the sensitivity can be improved, and the chip size can be reduced without degrading performance.

[0017]

As is apparent from the above description, in the solid-state imaging device of the present invention, the photoelectric conversion N-type layer includes the extension portion extending below the gate electrode toward the charge-transfer N-type layer. The area under the gate electrode, which was the ineffective area in the past, can be effectively used as an extension of the N-type layer for photoelectric conversion, and the photodiode capacity is improved, the smear component is prevented from being generated by obliquely incident light, and the sensitivity is improved. The chip size can be reduced without degrading the performance.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a solid-state imaging device of the present invention.

FIG. 2 is a sectional view of a conventional solid-state imaging device.

[Explanation of symbols]

11 N-type semiconductor substrate 12 P ⁻ type well 13 N ⁻ type impurity layer 14 P ⁺ type impurity layer 15 Pixel isolation region 17 Transfer channel 18 Gate insulating film 19 Gate electrode 20 P ⁻ type layer 100 Charge transfer part 101 Photoelectric conversion part

Claims (1)

[Claims] 1. A photoelectric conversion part including an N-type layer for photoelectric conversion formed on a P-type well formed on an N-type substrate; and a photoelectric conversion part formed in parallel with the photoelectric conversion part. A solid-state imaging device comprising a formed charge transfer N-type layer and a charge transfer unit including a gate electrode formed on the charge transfer N-type layer via a gate insulating film. The solid-state imaging device, wherein the mold layer includes an extension that extends below the gate electrode toward the charge transfer N-type layer.