JPH06120472A - Solid-state image sensing device - Google Patents

Abstract

PURPOSE:To provide a solid-state image sensing device having excellent sensitivity characteristic by increasing the numerical aperture of the photosensitive means without increase of a chip size. CONSTITUTION:A vertical transfer electrode plate 205 of the (2n-1)th (n is a natural number) line is provided at the vertical plane in the side of a photodiode 204 of the vertical transfer electrode plate 205 of the nth line buried in the depth direction for the surface of the semiconductor substrate 200 and the vertical transfer means 211 of the 2nth line is provided at the vertical plane in the side of the photodiode 209. Since the vertical transfer electrode plate 200 is provided only between the photosensitive means of the (2n-1)th line and 2nth line arranged in two-dimensional, the area occupied by the vertical transfer means is reduced, resulting in increase of the numerical aperture of the photosensitive means.

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 in which signal charges accumulated in a photosensitive portion are transferred by a plurality of columns of vertical charge transfer portions.

[0002]

2. Description of the Related Art In recent years, there has been a trend toward higher sensitivity for increasing the aperture ratio of a photosensitive section and a trend toward downsizing of a solid-state image pickup device. A schematic diagram of a conventional solid-state imaging device is shown in FIG. In FIG. 3, reference numeral 31 is a photosensitive portion that converts incident light into signal charges of a number proportional to the light intensity. Reference numeral 32 denotes a vertical charge transfer unit that vertically transfers the signal charges accumulated in the photosensitive units 31 arranged in a line in the vertical direction. A horizontal charge transfer unit 33 transfers the signal charges transferred from the vertical charge transfer unit 32 in the horizontal direction. An output unit 34 outputs the signal charges transferred from the horizontal charge transfer unit 33 to the outside of the solid-state imaging device.

The operation of the solid-state image pickup device configured as described above will be described below. First, in FIG. 3, the light received from the outside is incident on each photosensitive portion 31, and each photosensitive portion 31 is exposed.
It is photoelectrically converted into a signal charge in an amount corresponding to the light intensity.
After the signal charges are accumulated for a predetermined time, the vertical charge transfer unit 32
To the vertical charge transfer section 32 and the horizontal charge transfer section 33.
And is transferred to the output unit 34.

FIG. 4 is a horizontal sectional view of the solid-state image pickup device of FIG. 3 which passes through the photosensitive section 31 and the vertical charge transfer section 32. The photosensitive section at the m-th row and the n-th column (m and n are natural numbers). 31
And an enlarged view of the vertical charge transfer unit 32 in the n-th column. In FIG. 4, 400 is a semiconductor substrate. Reference numerals 401 and 402 denote light-shielding films arranged so that the external light A does not enter the areas other than the photosensitive section 31. Reference numerals 403 and 410 denote photodiodes (photosensitive portion 3) that photoelectrically convert incident light and store it as signal charges.
1). Reference numerals 404 and 411 are vertical transfer electrodes for transferring the signal charges from the photosensitive section 31 to the vertical charge transfer section 32. Reference numeral 405 is an insulating film such as silicon oxide for blocking the vertical transfer electrodes 404 and 411 from the semiconductor substrate 400. Reference numeral 406 is a read channel for blocking the photosensitive portion 31 and the vertical charge transfer portion 32 shown in FIG. 407, 4
Reference numeral 12 is a vertical transfer unit for transferring signal charges in the vertical direction. Reference numerals 408 and 409 denote element isolation layers for blocking the mixing of signal charges in the horizontal direction.

First, the external light A is blocked by the light shielding films 401 and 402, and is incident only on the photodiodes 403 and 410 not covered with the light shielding films 401 and 402. In the photodiodes 403 and 410, photoelectric conversion is independently performed according to the intensity of incident light and accumulated as signal charges. Vertical transfer electrode 404, insulating film 405, and read channel 4
Since 06 has a MOS structure in a portion 413 surrounded by a broken line, when a read voltage is applied to the vertical transfer electrode 404, the signal charge accumulated in the photodiode 403 is transferred to the vertical transfer unit 407. . Vertical transfer unit 407
Is a part of the n-th column (n is a natural number) of the vertical charge transfer unit 32 shown in FIG. 3, and the signal charges transferred to the vertical charge transfer unit 32 pass from the horizontal charge transfer unit 33 to the outside of the output unit 34. Is output to.

[0006]

However, in the above-mentioned conventional configuration, the vertical charge transfer section 32 of FIG. 3, that is, FIG.
Since the vertical transfer portions 407 and 412 are formed on both sides of the photosensitive portion 31 in a plane horizontal to the surface of the semiconductor substrate (chip), there is a problem that the aperture ratio of the photosensitive portion 31 cannot be increased.

An object of the present invention is to provide a solid-state image pickup device capable of increasing the aperture ratio of the photosensitive portion and increasing the sensitivity.

[0008]

In the solid-state image pickup device of the present invention, 2N columns (N is a natural number) of photosensitive units are two-dimensionally arranged on the surface of a semiconductor substrate, and the (2n-1) th column (n is The transfer electrode plate of the n-th row is embedded in the depth direction with respect to the surface of the semiconductor substrate at a position between the photosensitive part of the natural number) and the photosensitive part of the 2n-th column, and the transfer electrode plate (2n-1 ) The transfer unit of the (2n-1) th column is arranged on the vertical surface of the photosensitive unit side of the second column, and the transfer unit of the 2nth column is arranged on the vertical surface of the transfer electrode plate of the nth column on the photosensitive unit side of the 2nth column. Are arranged.

[0009]

According to the structure of the present invention, the transfer section of the (2n-1) th column and the transfer of the 2nth column are provided on both sides of the transfer electrode plate of the nth column buried in the depth direction with respect to the surface of the semiconductor substrate. By arranging the parts, in other words, (2n−
1) A transfer electrode plate and a transfer unit are provided only between the photosensitive unit of the 2nd column and the photosensitive unit of the 2nth column to form the photosensitive unit of the 2nth column (2
Since the transfer electrode plate and the transfer part are not provided between the photosensitive part of the (n + 1) th column, the ratio of the charge transfer part occupying the surface of the semiconductor substrate (chip) decreases, and the ratio of the charge occupying the chip surface of the photosensitive part is reduced. It is possible to increase the aperture ratio, the aperture ratio of the photosensitive portion is increased, and a solid-state imaging device having excellent sensitivity characteristics can be realized.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a solid-state image pickup device according to an embodiment of the present invention. In FIG. 1, reference numeral 11 denotes a photosensitive section that converts incident light into signal charges of an amount corresponding to the light intensity. Reference numeral 12 is a vertical charge transfer unit that transfers the signal charges accumulated in the photosensitive units 11 in two columns in the vertical direction without mixing each column. A horizontal charge transfer unit 13 transfers the signal charges transferred from the vertical charge transfer unit 12 in the horizontal direction. An output unit 14 outputs the signal charges transferred from the horizontal charge transfer unit 13 to the outside of the solid-state imaging device.

The operation of the solid-state image pickup device configured as described above will be described below. First, in FIG. 1, light received from the outside is incident on each photosensitive section 11, and is photoelectrically converted into a signal charge in an amount according to the light intensity in each photosensitive section 11. This signal charge is accumulated for a predetermined time, then transferred to the vertical charge transfer unit 12, and transferred to the output unit 14 via the vertical charge transfer unit 12 and the horizontal charge transfer unit 13.

FIG. 2 is a horizontal cross-sectional view of the solid-state image pickup device of FIG. 1 which passes through the photosensitive section 11 and the vertical charge transfer section 12. The photosensitive section (m, n) in the m-th row (2n-1) th column is shown in FIG. Is a natural number) and (2n-1) vertical charge transfer portions, (2n-1) vertical charge transfer portions, and (m) -th and 2n-th photosensitive portions are enlarged views. In FIG. 2, 200 is a semiconductor substrate. 201
Reference numerals 202 and 203 denote light-shielding films arranged so that the external light B does not enter the areas other than the photosensitive section 11. Reference numerals 204 and 209 denote photodiodes (photosensitive portion 11) that photoelectrically convert incident light and store it as signal charges.

Reference numeral 205 denotes the vertical charge transfer unit 1 from the photosensitive unit 11.
2 is a vertical transfer electrode plate having a T-shaped cross section for transferring the signal charges to the electrode 2. 206 is an insulating film for blocking the vertical transfer electrode plate 205 and the semiconductor substrate 200. 207 and 21
Reference numeral 0 is a read channel for blocking the photosensitive portion 11 and the vertical charge transfer portion 12 shown in FIG. Reference numerals 208 and 211 denote vertical transfer units for transferring signal charges in the vertical direction. Reference numeral 212 is a charge separation layer for blocking mixing of the charges transferred to the vertical transfer unit 208 and the vertical transfer unit 211. Two
Reference numerals 13 and 214 are element isolation layers for blocking the mixing of signal charges in the horizontal direction.

First, in FIG. 2, the external light B shields the external light B.
The light is incident only on the photodiodes 204 and 209 that are blocked by the light-shielding films 201 to 203 and are blocked by the light-shielding films 201 to 203. In the photodiodes 204 and 209, photoelectric conversion is independently performed according to the intensity of incident light and accumulated as signal charges. The vertical transfer electrode plate 205, the insulating film 206, and the read channel 207 have a MOS structure in a portion 215 surrounded by a broken line, and the vertical transfer electrode plate 205, the insulating film 206, and a read channel 210 are a portion 216 surrounded by a broken line. Since it has a MOS structure, the signal charge stored in the photodiode 204 is transferred to the vertical transfer unit 208 by applying a read voltage to the vertical transfer electrode plate 205, and the signal stored in the photodiode 209 is transferred. The charges are transferred to the vertical transfer unit 211.

The charges transferred to the vertical transfer units 208 and 211 are independent because they have a sufficient barrier in the charge separation layer 212. The vertical transfer units 208 and 211 are parts of the (2n−1) th column and the 2nth column of the vertical charge transfer unit 12 shown in FIG. 1, respectively.
The signal charges transferred to (1) are output to the outside from the output unit 14 via the horizontal charge transfer unit 13.

According to this solid-state image pickup device, one row of vertical transfer electrode plates 205 vertically embedded in the surface of the semiconductor substrate (chip) is provided, and two rows of vertical transfer electrode plates 205 are provided on both vertical surfaces. By separately configuring the units 208 and 211 and reducing the area occupied by the surface of the semiconductor substrate of the vertical charge transfer unit 12, the aperture ratio of the photosensitive unit 11 is increased, and a solid-state imaging device having excellent sensitivity characteristics can be realized. And

[0017]

According to the solid-state imaging device of the present invention, the transfer electrode plate is provided in a row vertically embedded in the surface of the semiconductor substrate (chip), and the transfer electrodes in one row are transferred in two rows on both vertical surfaces. Units are independently configured, and one row of transfer electrode plates and two rows of transfer portions are provided between the (2n-1) th column photosensitive section and the 2nth column photosensitive section, and the 2nth column photosensitive section is provided. Since the transfer electrode plate and the transfer section are not provided between the photosensitive section of the (2n + 1) th column, the area occupied by the surface of the semiconductor substrate of the charge transfer section can be reduced, and the aperture ratio of the photosensitive section can be increased. It is possible to realize a solid-state imaging device with excellent sensitivity characteristics, and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a solid-state imaging device according to an embodiment of the present invention.

FIG. 2 is a horizontal cross-sectional view passing through the photosensitive section and the vertical transfer section in the solid-state imaging device of one embodiment of the present invention.

FIG. 3 is a schematic diagram of a conventional solid-state imaging device.

FIG. 4 is a horizontal cross-sectional view passing through a photosensitive section and a vertical transfer section in a conventional solid-state imaging device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Photosensitive part 12 Vertical charge transfer part 13 Horizontal charge transfer part 14 Output part 201-203 Light-shielding film 204,209 Photosensitive part 205 Vertical transfer electrode plate 208,211 Vertical transfer part

Claims (1)

[Claims] 1. A 2N-column (N is a natural number) photosensitive section, a (2n-1) -th column (n is a natural number) photosensitive section, and a 2n-th photosensitive section that are two-dimensionally arranged on the surface of a semiconductor substrate. Between the transfer electrode plate on the n-th row and the transfer electrode plate on the (2n-1) -th row of the transfer electrode plate on the n-th row. Placed on a vertical surface (2n
-1) A solid-state imaging device including a transfer unit in the 2nd column and a transfer unit in the 2nth column arranged on a vertical surface of the transfer electrode plate in the nth column on the side of the photosensitive unit in the 2nth column.