JP3666211B2 - Solid-state image sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solid-state image sensor, particularly a CCD linear sensor.
[0002]
[Prior art]
5 and 6 (showing a pattern excluding the second layer Al light-shielding film from FIG. 5) are enlarged views of the main part of a conventional CCD linear sensor.
The CCD linear sensor 1 has a sensor array 2 in which a plurality of sensor units are arranged in one direction, and charge transfer using, for example, a two-phase drive CCD structure via a read gate unit 3 on one side of the sensor array 2. A register (hereinafter referred to as a CCD register) 4 is provided, and a shutter drain region 6 is provided on the other side of the sensor array 2 via a shutter gate portion 5.
[0003]
The sensor array 2 includes an effective pixel area 2A, an optical black (OPB) area 2B for setting a black level of a signal arranged on the output side thereof, and a dummy arranged outside the subsequent stage of the effective pixel area 2A. And a pixel region 2C. The dummy pixel region 2C is used for measuring transfer efficiency and MTF (Modulation Transfer Function) characteristics.
In the read gate portion 3, the gate electrode 14 is formed of the first polycrystalline silicon film.
In the CCD register 4, for example, a storage electrode 15 made of a first polysilicon film and a transfer electrode 17 made up of a transfer electrode 16 made of a second polysilicon film are formed.
In the shutter gate portion 5, the gate electrode 18 is formed of the first polycrystalline silicon film.
[0004]
Then, as shown in FIG. 6, the shunt Al wiring 20 connected to the gate electrode 18 through the insulating film is formed over the entire length parallel to the sensor row 2 on the gate electrode 18 of the shutter gate portion 5. Reference numeral 21 denotes a contact portion between the shunt Al wiring 20 and the gate electrode 18 made of a polycrystalline silicon film.
[0005]
On the other hand, apart from the shunt Al wiring 20 of the shutter gate portion 5, an Al light shielding film 22 that also serves as the shunt Al wiring in the readout gate 3 is formed. The Al light shielding film 22 is formed so as to cover the optical black region 2B other than the effective pixel region 2A of the sensor row 2 and the dummy pixel region 2C, the readout gate unit 3, and the CCD register 4 through an insulating film. The Reference numeral 23 denotes a contact portion between the gate electrode 14 made of a polycrystalline silicon film in the read gate portion 3 and the Al light shielding film 22 serving as a shunt wiring.
[0006]
The shunt Al wiring 20 and the Al light shielding film 22 of the shutter gate 5 are formed of the first Al film.
Further, in order to ensure the light shielding of the area to be shielded other than the effective pixel area 2A, the second Al film is formed on the entire surface other than the effective pixel area 2A through the insulating film as shown in FIG. An Al light shielding film 24 is formed.
[0007]
[Problems to be solved by the invention]
By the way, in the CCD linear sensor 1 described above, in order to simplify the configuration, reduce the manufacturing process, shorten the manufacturing time, etc., it is desired to further increase the thickness of the Al film used for the shunt wiring and light shielding.
However, when the second Al light shielding film 24 is omitted and a single layer Al structure as shown in FIG. 6 is adopted, the shunt Al wiring 20 and the Al light shielding film 22 are formed in the optical black region 2B and the dummy pixel region 2C in the subsequent stage. Light leaks from the slit-like gap 25 formed between them, and the light shielding for the optical black region 2B and the dummy pixel region 2C becomes incomplete.
This is because the shunt wiring on the shutter gate 5 side and the readout gate 3 side must be provided independently, and it is impossible to share both.
[0008]
In view of the above-described points, the present invention enables a further increase in the thickness of a shunt wiring and a metal film used for light shielding, and simplifies the configuration, reduces the manufacturing process, and reduces the manufacturing time, that is, a linear imaging device. A sensor is provided.
[0009]
[Means for Solving the Problems]
In the solid-state imaging device according to the present invention, the shunt wiring of the read gate unit is continuously provided over the portions corresponding to the optical black region of the charge transfer register unit, the read gate unit, the sensor array, and the optical black region of the shutter gate unit. A light shielding film is also formed, a shunt wiring is formed in the shutter gate portion including a portion corresponding to the effective pixel region, and the light shielding film and the shunt wiring are formed of the first metal film.
[0010]
Since the light shielding film serving also as the shunt wiring of the readout gate portion is continuously formed up to the portion corresponding to the optical black region and the optical black region of the shutter gate portion, the optical black region is completely shielded from light.
On the other hand, the shunt wiring on the shutter gate side is formed except for the portion corresponding to the optical black region.
Therefore, shunt wiring and light shielding can be performed by the first metal film.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
A solid-state imaging device according to the present invention is provided with a sensor column composed of an effective pixel region and an optical black region, a read gate unit and a charge transfer register unit arranged on one side of the sensor column, and a sensor column on the other side. A light-shielding film that also has a shutter gate portion and serves as a shunt wiring for the read gate portion is formed continuously on the charge transfer register portion, the read gate portion, the optical black region, and the portion corresponding to the optical black region of the shutter gate portion. The shunt wiring is formed in the shutter gate portion including the portion corresponding to the effective pixel region, and the light shielding film and the shunt wiring for the shutter gate portion are formed of the first metal film.
[0012]
According to the present invention, in the solid-state imaging device, the gate electrode of the shutter gate portion is formed of a polycrystalline semiconductor film, and the aluminum film is used as the first metal film.
[0013]
Embodiments of the present invention will be described below with reference to the drawings.
[0014]
FIG. 1 shows a schematic configuration of a solid-state imaging device, that is, a CCD linear sensor according to an embodiment of the present invention.
The CCD linear sensor 31 has a sensor array 33 in which a plurality of sensor sections 32 serving as pixels are arranged in one direction, and a two-phase drive CCD, for example, is connected to one side of the sensor array 33 via a readout gate section 34. A charge transfer register (so-called CCD register) 35 having a structure is provided, and a shutter drain region 37 is provided on the other side of the sensor array 33 via a shutter gate portion 36.
[0015]
Adjacent to the final stage of the CCD register 35, an output gate 39 and a floating diffusion region 40 to be a charge-voltage converter are formed, and a reset gate 41 and a reset drain 42 are formed to be adjacent to the floating diffusion region 40. Is done. An output circuit 43 is connected to the floating diffusion region 40.
[0016]
A read gate pulse φ _ROG is applied to the read gate unit 34, a reset pulse is applied to the reset gate unit 41, and a fixed voltage is applied to the output gate unit 39.
Two-phase drive clock pulses φH ₁ and φH ₂ are applied to the CCD register 35.
On the other hand, shutter means is constituted by the shutter gate 36 and the shutter drain region 37, and by applying a shutter pulse φ _SHUT to the shutter gate portion 36, the signal charges accumulated until then in the sensor array 33 pass through the shutter gate portion 36. And is discharged to the shutter drain region 37.
[0017]
In the CCD linear sensor, the same output level can be obtained for the same subject by shortening the charge accumulation time when the light source is too bright, and lengthening the charge accumulation time when the light source is too dark.
Further, for example, in a color CCD linear sensor, a plurality of, that is, three such linear sensors 31 are provided corresponding to red (R), green (G), and blue (B). In the case of a color CCD linear sensor, the white balance of the output voltages of R, G and B can be adjusted by the shutter means.
[0018]
FIG. 2 is an enlarged view of the main part of the CCD linear sensor 31 described above.
The sensor array 33 includes an effective pixel area 33A and an optical black (OPB) area 33B for setting a black level of a signal arranged on the output side thereof. A conventional dummy pixel region (so-called sensor portion structure) is not formed in 33C (referred to as a dummy portion for convenience).
[0019]
As shown in FIGS. 3 and 4, each sensor unit in the effective pixel region 33 </ b> A and the optical black region 33 </ b> B has a first conductivity type, for example, an n-type semiconductor substrate 61 and a second conductivity type, for example, a p-type semiconductor well region 62. It is formed and the p-type n-type semiconductor layer 63 by ion implantation is formed in the semiconductor well region 62, further comprising forming a charge storage region 64 of the p-type on the surface of the n-type semiconductor layer 63 so-called HAD (H ole A cumulative diode) sensor is used. 65 is a gate insulating film, and 66 and 67 are insulating films.
[0020]
In other words, in FIG. 2, in the effective pixel region 33A and the optical black region 33B indicated by diagonal lines, the n-type semiconductor layer 63 is formed by ion implantation to constitute each sensor unit 32, which corresponds to the conventional dummy pixel region. In the region, that is, the dummy portion 33C, the n-type semiconductor layer 63 is not formed, and no signal is output even if light leaks.
[0021]
In the read gate portion 34, the gate electrode 45 is formed of a first polycrystalline silicon film.
In the CCD register 35, a transfer electrode 48 is formed by, for example, a storage electrode 46 made of a first polysilicon film and a transfer electrode 47 made of a second polysilicon film.
In the shutter gate portion 36, the gate electrode 49 is formed of the first polycrystalline silicon film.
[0022]
In the present embodiment, the shunt wiring 50 of the shutter gate portion 36 and the light shielding film 53 for ensuring light shielding are formed by the first metal film, for example, an Al film.
[0023]
That is, the shunt wiring 50 of the shutter gate portion 36 is formed partway, that is, except for the portion corresponding to the optical black region 33B with respect to the gate electrode 49 of the polysilicon film of the shutter gate portion 36 as shown in the figure. A shunt wiring 50 connected to the gate electrode 49 through an insulating film is formed on a portion corresponding to the region including the effective pixel region 33A. Reference numeral 51 denotes a contact portion between the shunt wiring 50 and the gate electrode 49 made of a polycrystalline silicon film.
[0024]
On the other hand, the light-shielding film 53 that also serves as the shunt wiring of the readout gate section 34 independent of the shunt wiring 50 of the shutter gate section 36 is the CCD register 35 other than the effective pixel area 33A of the sensor array 33, and the readout gate section. 34, the optical black region 33B, the dummy portion 33C on the rear side of the effective pixel region 33A, and the shutter gate portion corresponding to the optical black region 33B, that is, over the gate electrode 49 where the shunt wiring 50 is not formed. It is formed continuously through an insulating film so as to cover. Reference numeral 54 denotes a contact portion between the gate electrode 45 made of the polycrystalline silicon film of the read gate portion 34 and the light shielding film 53 acting as a shunt wiring.
[0025]
According to the CCD linear sensor 31 described above, the shunt wiring 50 of the shutter gate portion 36 is not formed in the portion corresponding to the optical black region 33B, and only the gate electrode 49 made of a polycrystalline silicon film is used in this portion. By forming the light shielding film 53 different from the wiring 50 for use on the optical black region 33B and the shutter gate portion 36 corresponding to the optical black region 33B, light leakage does not occur in the optical black region 33B. It can be completely shielded from light.
[0026]
On the other hand, in the dummy portion 33C, a slit-like gap 56 is formed between the light shielding film 53 and the shunt wiring 50, and light leakage occurs from the gap 56, but the sensor portion is not configured in the dummy portion 33C. Since there is no charge accumulation, it is not output as a signal.
Since the transfer efficiency and MTF characteristics can be measured using the effective pixels and the subsequent idle feed area of the CCD register, the dummy pixel area can be omitted.
[0027]
Therefore, light shielding and shunt wiring can be performed by the first Al film, the configuration is simplified, and the cost of the CCD linear sensor can be reduced.
Moreover, since the manufacturing process of such a CCD linear sensor can be reduced, the manufacturing yield can be improved.
Furthermore, the manufacturing time of the CCD linear sensor can be shortened.
[0028]
The present invention can be applied to a color CCD linear sensor, a monochrome CCD linear sensor, and the like.
[0029]
【The invention's effect】
According to the solid-state imaging device according to the present invention, light shielding and shunt wiring can be enabled by the first metal film, the configuration can be simplified, and the cost can be reduced.
Moreover, the manufacturing process of such a solid-state image sensor can be reduced, and the manufacturing yield can be improved.
Furthermore, the manufacturing time of a solid-state image sensor can be shortened.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an embodiment of a solid-state imaging device according to the present invention.
FIG. 2 is an enlarged view of a main part of an embodiment of a solid-state imaging device according to the present invention.
FIG. 3 is a cross-sectional view of an effective pixel region according to an embodiment of a solid-state imaging device according to the present invention.
FIG. 4 is a cross-sectional view of an optical black region according to an embodiment of a solid-state imaging device according to the present invention.
FIG. 5 is an enlarged view of a main part of a conventional CCD linear sensor.
6 is a configuration diagram excluding the second-layer Al light shielding film from FIG. 5. FIG.
[Explanation of symbols]
31 ... CCD linear sensor, 32 ... Sensor section, 33 ... Sensor array, 33A ... Effective pixel area, 33B ... Optical black area, 33C ... Dummy section, 34 ... Read gate section, 35 ... Charge Transfer register section 36 ... Shutter gate section 37 ... Shutter drain area 45 ... Read gate section gate electrode 48 ... Transfer electrode 49 ... Shutter gate section gate electrode 50 ... Shut gate section Wiring for shunts, 53 ... light shielding film

Claims (2)

A sensor array comprising an effective pixel area and an optical black area;
A readout gate portion and a charge transfer register portion arranged on one side of the sensor array;
A shutter gate portion disposed on the other side of the sensor row;
A light-shielding film that also serves as a shunt wiring of the read gate portion is formed continuously over the portion corresponding to the optical black region of the charge transfer register portion, the read gate portion, the optical black region, and the shutter gate portion,
Shunt wiring is formed in the shutter gate portion including a portion corresponding to the effective pixel region,
A solid-state imaging device, wherein the light shielding film and the shunt wiring for the shutter gate portion are formed of a first metal film. A gate electrode of the shutter gate portion is formed of a polycrystalline semiconductor film;
The solid-state imaging device according to claim 1, wherein an aluminum film is used as the first metal film.

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