JPH021978A - Solid-state image sensing device - Google Patents

Abstract

PURPOSE:To obtain an image sensing device which is free from the effect of light rays leaked in from the periphery of a bonding pad and easily manufactured by a method wherein a second conductivity type second semiconductor region is formed on a region of a semiconductor substrate, which includes lower parts of the bonding pad and the part not covered with a light shielding layer around the bonding pad and is apart from a first semiconductor region. CONSTITUTION:Light is leaked in from the gap (non-covered part) of a light shielding aluminum layer 7a provided around a bonding pad 13, and a positive charge Q is generated inside an n-type silicon region 14 through the leaked gap. The charge Q diffuses around the n-type silicon region 14 until it re-joins together but it does not move outside of the n-type silicon region. And, the n-type silicon region, which the light rays are incident on, is electrically connected with an aluminum wiring layer 5a so as to be fixed at a constant voltage, so that the charge Q generated in the n-type silicon region 14 is swept outside through the aluminum wiring layer 5a.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to solid-state imaging devices such as COD (
There is.

[Conventional technology]

Figure 3(a) shows the schematic configuration of a conventional solid-state @imaging device.
FIG. 4 is a sectional view taken along the line AA in FIG. 3(a). This solid-state VI image device is a one-dimensional solid-state image device in which pixels are arranged in a 1911 pattern. Silicon region 2
A substrate 1 containing this n-type silicon full or 2 is formed.
A silicon oxide film 3 is formed in a predetermined region above. Furthermore, a polysilicon layer 4a is formed on the upper silicon oxide film 3;
Another polysilicon layer 4b separated from the polysilicon layer 4a is also formed in a portion corresponding to a position away from the n-type silicon region 2. Further, a part of the silicon oxide film 3 is removed, and an aluminum wiring m5a electrically connected to the p-type silicon substrate 1 is selectively formed on the silicon oxide film 3F-, while a first aluminum wiring m5a is formed on the polysilicon:In layer 4b. An aluminum layer 5b is formed. After the silicon oxide film 6 is formed on the soil in all these areas, a part of the silicon oxide layer 6 on the first aluminum layer 5b is removed, and a second aluminum layer 7b is laminated on the first aluminum layer 5b. A bonding pad is formed. Also, the second aluminum layer 7 which becomes this bonding pad
A light-shielding aluminum layer 7a is also formed in other regions on the silicon oxide film 6 except for the area b. However, the second aluminum IE that becomes the bonding pad! This light-shielding aluminum layer 7
a is not formed. This is done to make it easier to detect bonding pads during bonding work.

FIG. 5 is a plan view showing a specific structure of the n-type silicon region 2 shown in FIGS. 3(a) and 4(r).

In the figure, the left side of the n-type silicon ffi region 2 constitutes a light receiving section 2a, and the right side constitutes a charge transfer section 2b. 8 is a transfer gate.

In this solid w* device a, as a measure to prevent the detection of the bonding pad during the bonding pad work as described above, a light-shielding aluminum layer is applied only to the periphery of the second aluminum layer 7b, which is the bonding pad. The formation of 7a is omitted.

Therefore, light enters the p-type silicon root 1 through the gap as shown in FIG. 4, and a negative charge Q is generated in the substrate 1, which is diffused into the r1-type silicon region 2. do. In this way, since the diffused charge is added to the signal charge in the QSn type silicon region 2, the signal output of each pixel is affected by the incidence of light at each bonding pad, as shown in FIG. 3(b). You'll end up making a lot of noise.

“Physics of Sem1c” by S, M, sze
1st edition (1969)
), formula [5] disclosed in P, 661 [: Diffusion length D = Diffusion coefficient τ: Lifetime D = 30ct/sec, z: = 8
As derived from
Therefore, in the case of the solid-state positive image device described above, in order to reduce the noise caused by the leakage of light from the periphery of the bonding pad, the position of the bonding pad must be changed to the charge transfer part 2b, that is, the n-type series 1. It must be separated from the contact area 2 by about 200 to 300 micrometers, which will reduce the degree of integration.

Therefore, as a means to solve such problems, as shown in FIG.
A type silicon region 12 is formed, and this n-type silicon region 1
2 contains a type 1 silicon region [
It is conceivable to form 2. In the figure, 2 to 7a
, 7b are the same parts as in the case of FIG.

In the solid-state image transfer device configured in this way, the negative charge QBp-type silicon region 1 caused by light leaking from the periphery of the second aluminum lm7b, which is the bonding pad, is
412, if this n-type silicon region 12 is fixed at a constant potential, the diffused charge Q can be prevented from reaching the n-type silicon region 2 in the p-type silicon region I412. Gade monkey.

(Problems to be Solved by the Invention) As described above, the conventional solid-state 1li in which noise is caused by light leaking from the periphery of the bonding pad.
The problems of the i-image device can be improved by adopting the structure shown in FIG. It is difficult to control the impurity concentration when forming the n-type silicon region 12 and then forming the [1-type silicon] region 2 that constitutes the light receiving section and the 'tri load transfer section within the n-type silicon region 12, and therefore the manufacturing process is difficult. The problem is that it is difficult.

The present invention has been made to solve these problems, and an object of the present invention is to provide a solid-state imaging device that is not affected by light leaking from the periphery of the bonding pad and is easy to manufacture.

(Means for Solving the Problems) A solid-state prisoner 81 device according to the present invention includes a first semiconductor of a second conductivity type formed on a semiconductor substrate of a first conductivity type and constituting a light receiving section and a charge transfer section. and a bonding pad formed on the semiconductor substrate apart from the first semiconductor region, and a predetermined region excluding the bonding pad and its peripheral portion is covered with a light-shielding layer. The imaging device includes a second conductive layer on the semiconductor substrate in a region including a lower part of the bonding pad and a portion around the bonding pad that is not covered with the light shielding layer and is away from the first semiconductor region. A type second semiconductor region is formed and the second semiconductor region is fixed at a predetermined potential.

(Function) In the present invention, charges are generated in the second semiconductor region formed in the region including the lower part of the bonding pad due to light leaking from the periphery of the bonding pad. 1° (Embodiment) FIG. 1 is a vertical sectional view of an embodiment of a solid-state imaging device according to the present invention, and FIG. FIG.

This solid-state HaF'A device is a one-dimensional solid state with pixels arranged in a row! b: Image installation, 1 to 7a, 7[ in the figure
) [Not shown in FIG. 1, the conventional device and fjl- or equivalent parts are removed. In this solid-state imaging device, a polysilicon layer 4b stacked on a silicon oxide film 3, a first aluminum br
b Add a second aluminum layer 7b on top of b
An n-type silicon region 14 is formed in a predetermined region on the p-type silicon substrate 1, including the lower part of the bonding pad 1J3 formed by the bonding pad 1J3 and the F portion around the bonding pad 13 which is not covered by the light-shielding aluminum In7a. ing. The nJp silicon region 14 is formed separately from the n-type silicon region 2 constituting the light receiving section and the charge transfer section, and is formed separately from the aluminum wiring 15a selectively formed on the silicon oxide film 3. It is designed to be electrically connected to this n-type silicon region 1414 and fixed at a constant potential.

In the case of this solid-state imaging device, the gap (
Positive charges Q are generated in the r1 type silicon region 14 by light leaking from the uncovered portion).

These charges Q are recombined until ℃ ``type 1 silicon region 14
However, this n-type silicon region j or 14
I never go outside. Therefore, the n-type silicon region 2 constituting the light receiving section and the charge transfer section is not affected by leaking light. In addition, since the "1 type silicon region 14 on which light is incident is electrically connected to the aluminum wiring layer 5a and fixed at a constant potential, this n-type silicon region 14
The charges Q generated inside are swept out to the outside through the aluminum wiring layer 5a.

In this embodiment, the n-type silicon region 2 constituting the light emitting part and the charge transfer part on the p-type silicon base 1 is separated, and another n-type silicon region 14 is formed in the region including the bonding pad 13 part. Since it forms, the ions that form it? One person does not have any difficulty in controlling the impurity temperature at 11.

4. In the above embodiment, a one-dimensional solid-state imaging device in which pixels are arranged in a single row was explained as an example, but the invention is not limited to this, and a two-dimensional solid-state imaging device in which pixels are arranged in a matrix in a vertical and horizontal manner is also applicable. By applying the present invention to Embodiment 6L, it is possible to obtain the same effects as in Example 6L.

〔Effect of the invention〕

As described above, according to the present invention, the charges generated in the semiconductors S and Lli due to light leaking from the peripheral portion of the bonding pad are absorbed by the semiconductor conductor formed in the region including the bonding pad 18 and the reverse conduction. 21'! Since the light is taken into the second semiconductor region of the light receiving part J3,
and the first semiconductor region constituting the charge transfer section, and prevents the influence of the incident light described above from reaching the first semiconductor region constituting the charge transfer section. The formation of the second semiconductor region also has the advantage that it can be manufactured easily since it does not pose any national crisis.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of a solid-state imaging device according to the present invention, FIG. 2 is a plan view of the solid-state positive imaging device, and FIGS. 3(a) and 3(b) are respectively A top view of the solid-state imaging device; a waveform diagram showing its signal output; FIG. 4 is a sectional view taken along the line A-A in FIG. 3(a); and FIG. ) type silicon region, and FIG. 6 is a vertical cross-sectional view showing a structure improved from the conventional solid-state wl image device. In the figure, 1 is a p-type silicon region, 2 and 14 is n
5a is an aluminum wiring layer, and 13 is a bonding pad. Note that the same reference numerals in each figure represent the same or equivalent parts. Agent Masuo Oiwa

Claims (1)

[Claims] (1) A first semiconductor region of a second conductivity type formed on a semiconductor substrate of a first conductivity type and constituting a light receiving section and a charge transfer section, and a first semiconductor region of a second conductivity type formed on the semiconductor substrate away from the first semiconductor region. In the solid-state imaging device, the solid-state imaging device includes a bonding pad that is formed on the semiconductor substrate, and a predetermined area excluding the bonding pad and its surrounding area is covered with a light-shielding layer. A second semiconductor region of a second conductivity type is formed in a region including the lower part of the uncovered portion and is away from the first semiconductor region, and the second semiconductor region is fixed at a predetermined potential. Characteristic solid-state imaging device.