JPH04280680A - S0lid-state image pickup device - Google Patents

Abstract

PURPOSE:To enable an FD region in the output section of a solid-state image pickup device to be miniaturized so as to enhance the image sensing device in sensitivity and output power. CONSTITUTION:In the output section of a solid-state image pickup device, a signal wiring of doped polysilicon 20 is provided onto a semiconductor substrate 19 provided with an FD (floating diffusion) region 9 through the intermediary of an insulating layer where a contact hole 17 is bored, and the dopant contained in the polysilicon 20 is made to diffuse into the FD region 9 through the intermediary of the contact hole 17 to bring the FD region 9 into contact with the signal wiring.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a solid-state imaging device.
In particular, FDA (FloatingD
The present invention relates to the structure of the output section of the Amplifier (Amplifier) configuration.

0002

2. Description of the Related Art As an example of a solid-state imaging device, FIG.
Shown below. In the figure, there are a plurality of photosensor sections 1 that are two-dimensionally arranged in pixel units in the horizontal and vertical directions and accumulate signal charges according to the amount of incident light, and a plurality of photosensor sections 1 that are read out in each vertical column from these photosensor sections 1. An imaging section 3 includes a vertical shift register (vertical transfer section) 2 that vertically transfers the output signal charges. In this imaging section 3, the photosensor section 1 is composed of, for example, a photodiode, and the vertical shift register 2 is a CCD (Charge Co., Ltd.).
Upled Device). The signal charges transferred to the vertical shift register 2 are sequentially transferred to the horizontal shift register (horizontal transfer section) 4 in portions corresponding to one scanning line during a part of the horizontal blanking period. The signal charges for one scanning line are sequentially transferred in the horizontal direction by the horizontal shift register 4. At the final end of the horizontal shift register 4, an output section 5 is arranged that detects the transferred signal charge and converts it into an electrical signal.

As this output section 5, one having an FDA configuration as shown in a plan view of FIG. 3 is known. This FD
The output section 5 of the A configuration has an output MO on the same chip as the CCD.
An S transistor 6 is formed, and a gate electrode 7 of this output MOS transistor 6 is connected to an F transistor provided adjacent to a horizontal output gate (HOG) 8 at the final stage of the horizontal shift register 4.
It has a structure connected to a D (floating diffusion) region 9. The operation is as follows: By applying a reset pulse to the reset gate 10, the potential of the FD region 9 is reset by the voltage applied to the reset drain 11, and then, with the reset gate 10 turned off, the signal charge is horizontally The signal is injected into the FD region 9 through the output gate (HOG) 8, the change in signal potential is detected, and the output MOS transistor 6 amplifies and outputs the signal.

Conventionally, in this type of output section 5, as shown in FIG.
As shown in the cross section along line A-A' in FIG. 3, field oxide film (SiO2) 12 and gate oxide film (SiO2) 13
After forming polysilicon (P) containing phosphorus (P),
-doped-polySi)14 output MOS
Wire a signal line between the gate electrode 7 of the transistor 6 and the FD region 9, and further form an N+ region 15 by injecting phosphorus into the N-type source (FD region) 9 and drain 11.
PSG (Phosho-Silicate Glass)
), etc., and then a contact hole 17 is formed to make a contact (electrical connection) with aluminum 18, for example.

[0005]

[Problems to be Solved by the Invention] However, the contact portion in the conventional output section 5 having the above configuration is limited to the N+ region 1.
Since the formation is performed using three masks: a mask for forming the contact hole 17, a mask for forming the contact hole 17, and a mask for making contact with the aluminum 18, each mask misalignment, line width, etc. It is necessary to design a larger margin for processing errors, and the N+ area 1
Since phosphorus forming 5 has a large lateral diffusion, N
+ The surface area of the region 15 has to become large, which hinders miniaturization and high sensitivity of the FD region 9. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a solid-state imaging device that enables miniaturization of the FD area in the output section and correspondingly higher sensitivity and higher output.

[0006]

[Means for Solving the Problems] A solid-state imaging device according to the present invention contains a dopant in an output portion of a semiconductor substrate having a FD (floating diffusion) region through an insulating layer in which a contact hole is formed. The signal line wiring is made of polysilicon, and the dopant contained in the polysilicon is diffused into the FD region through a contact hole.

[0007]

[Operation] In the solid-state imaging device according to the present invention, a high concentration impurity region is formed by diffusing the dopant in the polysilicon forming the signal line wiring into the FD region through the contact hole. Make contact with the area and the signal line. In this way, by forming a high concentration impurity region in a contact hole in a self-aligned manner, the FD region can be made smaller, and the accompanying capacitance can be reduced to achieve higher sensitivity and higher output.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional structural diagram of an output section in a solid-state imaging device according to the present invention, and shows a cross section taken along the line AA' in FIG. In the figure, on the front side of the semiconductor substrate 19, there is a
An N-type FD region 9 is formed adjacent to the final stage horizontal output gate 8 of the horizontal shift register 4 shown in FIG. A field oxide film (SiO2) 12 and a gate oxide film (SiO2) 13 are formed on the semiconductor substrate 19, and the field oxide film 12 is formed using a mask (not shown) above the approximate center of the FD region 9. A contact hole 17 is then formed. Between this contact hole 17 and the gate electrode 7 of the output MOS transistor 6, for example, arsenic (As)
) as a dopant (As-d
Wiring of signal lines is performed using oped-polySi) 20. In the contact hole 17 portion, arsenic in the polysilicon 20 is diffused into the FD region 9 through the contact hole 17 by heat treatment, and an N+ region 21 is formed.
is formed to make contact between the FD region 9 and the signal line made of polysilicon 20. Then, an interlayer insulating film 16 made of PSG or the like is applied.

As described above, in the output section 5 of the CCD solid-state imaging device, the polysilicon 20 and the FD region 9 which form the signal wiring to the gate electrode 7 of the output MOS transistor 6 are connected to each other.
The contact part with the so-called buried contact (bur
ied contact) structure, polysilicon 20
The arsenic contained therein is transferred to the FD through the contact hole 17.
By diffusing into region 9 and forming N+ region 21 by self-alignment, as in the conventional example using three masks,
Since there is no need to design a larger margin due to processing errors such as mask misalignment and line width, the contact area can be made smaller by that amount, so the FD area 9 can be made smaller, and the resulting reduction in capacitance allows for higher sensitivity and higher sensitivity. High output can be achieved. Furthermore, since the signal wiring to the gate electrode 7 is formed using polysilicon 20 containing arsenic, and the N+ region 21 is formed by diffusion of arsenic in this polysilicon 20, the lateral diffusion of arsenic is small. Therefore, since the surface area of the N+ region 21 can be reduced, the FD
This means that the area 9 can be further miniaturized.

0010

[Effects of the Invention] As explained above, according to the present invention,
In the output section of the solid-state imaging device, a signal line is wired using polysilicon containing a dopant through an insulating layer in which a contact hole is formed on a semiconductor substrate having an FD region, and the dopant in this polysilicon is By forming a high concentration impurity region by diffusing it into the FD region through the contact hole, the high concentration impurity region can be formed in the contact hole with self-alignment. The reduction in capacitance has the effect of contributing to higher sensitivity and higher output.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional structural diagram showing an output section in a CCD solid-state imaging device according to the present invention, and shows a cross section taken along line AA' in FIG.

FIG. 2 is a configuration diagram of an example of an interline transfer type CCD solid-state imaging device.

FIG. 3 is a plan view of the structure of an output section in the CCD solid-state imaging device.

4 is a cross-sectional structural diagram showing a conventional output section, showing a cross section taken along line AA' in FIG. 3. FIG.

[Explanation of symbols]

1 Photo sensor part 2 Vertical shift register 4 Horizontal shift register 5 Output section 6 Output MOS transistor 8 Horizontal output gate 9 FD (floating diffusion) area 12 Field oxide film 13 Gate oxide film 17 Contact hole 20 Polysilicon containing arsenic

Claims (1)

[Claims] 1. In an output section of a solid-state imaging device, a signal is generated by polysilicon containing a dopant on a semiconductor substrate having a floating diffusion region through an insulating layer in which a contact hole is formed above the floating diffusion region. What is claimed is: 1. A solid-state imaging device, characterized in that the dopant in the polysilicon is diffused into the floating diffusion region through the contact hole.