JP3047535B2 - Charge transfer device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge transfer device, and more particularly to a charge transfer device in which a transparent coating layer is formed on an upper surface of a light receiving portion to prevent foreign matter from adhering to the upper surface of the light receiving portion.

[0002]

2. Description of the Related Art A conventional charge transfer device is shown in FIG.
As shown in (b), a light-receiving photodiode is formed by providing an N-type diffusion region 2 on a P-type substrate 1, and a first metal coating 4 is formed on the upper surface of the P-type region via an insulating oxide film 3a. It has a photoelectric conversion region in which a second metal coating 5 is formed on the upper surface of the first metal coating 4 via an insulating oxide film 3b. The N-type diffusion regions 2 are separated by a channel stop region 10. Therefore, the light receiving area of the light receiving portion photodiode is a region surrounded by the channel stop region 10 and the first metal coating 4. Usually, since the first metal coating 4 is used for wiring of an electric circuit, the second metal coating 5 is formed for light shielding so as not to reduce the light receiving area surrounded by the first metal coating.

The charge generated by photoelectric conversion in the light-receiving photodiode is output as a voltage by the transfer region in the same manner as in a normal charge transfer device. I did not fill in 6.

[0004]

In this conventional charge transfer device, the step of the first metal coating 4 and the step of the second metal coating 5 overlap with the light receiving area of the photodiode of the light receiving portion, and the light receiving region overlaps the light receiving region by 2 μm.
A groove of m to 2.5 μm is formed. If a foreign substance of several μm falls into this groove, there is a problem that light incidence is hindered and output unevenness of the charge transfer device is caused. Normally the light-receiving region is 7μm ² ~14μm ^2, for example, black foreign matter in the case 2 [mu] m ² of the light-receiving region of 7 [mu] m ² falls on the light receiving regions groove 2 × 2/7 × 7 = 4/49 = 0.082 Then, 8.2% output unevenness occurs.

[0005]

A charge transfer device according to the present invention comprises a photoelectric conversion region formed by an N-type diffusion region formed on a P-type substrate for converting an optical signal into an electric signal, and a light receiving region of the photoelectric conversion region. A first metal coating for controlling, further a second metal coating for preventing light from entering a portion other than the light receiving region, and covering the light receiving region directly above the light receiving region to prevent a step of the light receiving region And a transparent coating layer formed as described above.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a charge transfer device according to one embodiment of the present invention. Since the transfer area is the same as the conventional one, it is omitted from the drawing and the description is omitted.

An N-type diffusion region 2 is formed on a P-type substrate 1,
An insulating oxide film 3a is formed on a shaped substrate 1, and a first metal coating 4 for limiting a light receiving region is further formed thereon.
Next, an insulating oxide film 3b is formed on the first metal coating 4,
Next, a second metal coating 5 for light shielding is formed in a portion other than the light receiving region. Next, a transparent coating layer 6 for preventing foreign matter from falling into the light receiving region is formed on the light receiving region.

FIG. 2 is a diagram showing a patterning method when a positive photoresist film is used as the material of the transparent coating layer 6. In FIG. 2A, a positive photoresist film is applied on an ordinary charge transfer device having a large step. Next, as shown in FIG. 2B, patterning is performed using a photolithography technique by using a photomask 7 in a portion where a photoresist film is to be left in a dark portion 7a.

FIG. 3 is a plan view of the charge transfer device. A transparent coating layer 6 (photoresist) is formed so as to cover the central light receiving region. FIG. 1 is a sectional view taken along the line AA 'in the figure.

According to the present invention, even if a foreign substance such as dust comes near the light receiving area, the barrier of the transparent coating layer 6 exists immediately above the light receiving area. Therefore, there is an effect that the output unevenness of the charge transfer device does not occur.

FIG. 4 is a sectional view showing a second embodiment of the present invention, and FIG. 5 is an overall plan view of the second embodiment. FIG. 4 is a sectional view taken along the line BB 'of FIG. 1 and 2 are given the same numbers. The difference from the first embodiment is that the transparent coating layer is extended not only above the light receiving area but also over the second metal coating. In this case, a barrier can be formed outside the N-type diffusion region 2 forming the photodiode, and foreign materials such as dust can be fixed away from the N-type diffusion region by using an adhesive material as the transparent coating layer. There is an effect that can be.

Although the present invention uses a P-type substrate in the embodiments, the present invention is not limited to a P-type substrate, and a P-type region may be formed on an N-type substrate.

[0013]

As described above, according to the present invention, since the transparent covering layer is formed on the concave portion of the light receiving region or on the second metal coating including the concave portion, foreign substances such as dust can be prevented from getting on the light receiving region. This has the effect of eliminating output unevenness of the charge transfer device.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a first embodiment of the present invention.

FIG. 2 is a process chart for realizing FIG. 1;

FIG. 3 is an overall plan view of the charge transfer device having the structure of FIG. 1;

FIG. 4 is a cross-sectional view showing a second embodiment.

5 is an overall plan view of the charge transfer device having the structure shown in FIG. 4;

FIG. 6A is a schematic plan view showing a main part of a conventional example, and FIG.
Is a sectional view of a main part of a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 P-type substrate 2 N-type diffusion region 3 a, 3 b insulating oxide film 4 first metal coating 5 second metal coating 6 transparent coating layer 7 photomask 10 channel stop region

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 27/14 H04N 1/028 H04N 5/335

Claims (3)

(57) [Claims] A photoelectric conversion region for converting an optical signal into an electric signal; and a transfer region for transferring and outputting a charge generated in the photoelectric conversion region, wherein the photoelectric conversion region is formed on the photoelectric conversion region via an insulating oxide film. A first metal coating formed to control the area; and a first light-shielding layer formed on the first metal coating via an insulating oxide film to prevent light from entering other than the photoelectric conversion region. 2. The charge transfer device according to claim 2, wherein a transparent coating layer is provided in a convex shape on the photoelectric conversion region. 2. A photoresist having a positive transparent coating layer.
The charge transfer device according to claim 1, wherein 3. A light receiving area on a first conductivity type semiconductor substrate.
Forming a second conductivity type diffusion region, and forming a first conductivity type diffusion region on the semiconductor substrate;
An insulating film is formed on the outside of the second conductivity type diffusion region.
Forming a first metal coating on said insulating film;
Not covered with and covered by the first metallization;
Forming a second insulating film on the first insulating film,
Forming a metal coating on the second insulating film at a position other than the light receiving region;
And a positive photoresist is applied over the entire surface
Then, the photoresist is patterned by photolithography.
On the light receiving area, the convex shape made of the photoresist
Forming a transparent coating layer of
Of manufacturing a charge transfer device.