JPH0287683A - Photodiode - Google Patents

Abstract

PURPOSE:To acquire a large photosensitive current without increasing an annode by providing a transistor inside a guard ring which encloses the annode. CONSTITUTION:A guard ring 3 is formed in an n-type substrate (first conductivity region) 1 of high resistivity to enclose a region of an annode 2 through n-type impurity diffusion. Then p-type impurity is ion-implanted to an annode region and a base region inside the guard ring, and an annode (second conductivity region) 2 and a base 7 are formed simultaneously. After an emitter 8 is formed through n-type impurity diffusion inside the base, a contact hole for electrode connection is formed on an insulating film 4 on the surface. Aluminum evaporation and aluminum patterning are made to form each electrode and to manufacture a photodiode.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to photodiodes.

[Conventional technology]

Conventionally, photodiodes are manufactured by selectively diffusing or ion-implanting p-type impurities into the surface of a high-resistivity n-type silicon substrate 31 to form an anode 32, as shown in FIG. is formed by diffusing or ion-implanting n-type impurities.

[Problem to be solved by the invention]

The light-receiving sensitivity of the photodiode is proportional to the area of the anode 32, so in order to obtain a large light-receiving current, the anode 32
It is necessary to greatly expand the As described above, in the conventional photodiode described above, the light-receiving sensitivity and the anode area are in a directly proportional relationship, so in order to increase the sensitivity, the anode, and therefore the pellet area, must be increased.

However, when the anode is made larger, it is difficult to make the pn junction formed between the anode and the substrate uniform over the entire area, resulting in problems such as deterioration of characteristics and reduction in yield.

The present invention aims to solve the above-mentioned problems by providing a structure in which a large light-receiving current can be obtained without increasing the size of the anode.

[Means to solve the problem]

The photodiode of the present invention has a structure in which a transistor is provided in a guard ring surrounding an anode.

[Example 1] Next, the present invention will be explained with reference to the drawings.

FIG. 1(a) is a longitudinal sectional view of one embodiment of the present invention, and FIG. 1(b) is its equivalent circuit. A guard ring 3 is formed on a high resistivity n-type substrate (first conductivity type region) 1 by diffusing an n-type impurity (P is used in this embodiment) so as to surround a region to be an anode 2. Next, a p-type impurity (B was used in this example) is ion-implanted into the anode region surrounded by the guard ring and the base region within the guard ring, and at the same time, the anode (second conductivity type region) 2 and the base are implanted. form 7. Furthermore, after diffusing n-type impurities into the base to form an emitter 8, contact holes for electrode connection are made in the insulating film 4 on the surface, and aluminum vapor deposition and aluminum patterning are performed to form each electrode. Manufacture a diode.

In addition to a light receiving part including an anode 2, this photodiode is equipped with a transistor whose collector is a guard ring.
The photocurrent obtained in the light receiving section is passed through the anode 2 and the wiring 5, and is amplified by a transistor and output. Therefore, with the same light-receiving area, more current can be extracted than a conventional photodiode by the amount amplified by the transistor.

[Example 2] FIG. 2 is a longitudinal sectional view of Example 2 of the present invention.

Anode 2. The structure and manufacturing method are the same as in Example 1 until the base 7 is formed, but when the emitter 8 is formed, the concentration is further increased by simultaneously diffusing into the anode side 9 of the guard ring 3. It is more effective.

The rest is the same as in the first embodiment.

〔Effect of the invention〕

As explained above, the present invention allows transistors to be easily integrated by forming a transistor in the guard ring of a photodiode, and also amplifies the light-receiving current of the photodiode without changing the light-receiving area. The light receiving current is multiplied by h14, and the pellet can be further reduced in size.

In each of the embodiments, the light-receiving section is composed of a photodiode having a pn junction, but it may also be a so-called bin photodiode having a pin structure. Further, the transistor provided in the guard ring is not limited to a bipolar type transistor, but may be a MO'S type transistor or a Schottky junction type transistor.

4... Insulating film, 7... Base, 8... Emitter, 31... N-type substrate, 32... Anode, 33...
... Guard ring, 34... Insulating film.

Claims (1)

[Claims] A photodiode comprising a light receiving section having at least a first conductivity type region and a second conductivity type region, and a first conductivity type guard ring around the second conductivity type region, wherein the inside of the guard ring is provided with a first conductivity type guard ring. A transistor is formed in which a region of a first conductivity type, a second conductivity type, or both conductivity types is provided, and the guard ring is a part of an active region, and the transistor and the second conductivity type region are electrically connected. Features photodiode.