JPH06204548A - Light-sensing semiconductor device, manufacture thereof and photocoupler using same - Google Patents

Abstract

PURPOSE:To make it possible to change a current transfer rate by changing a wiring and to construct two light-sensing circuits in the case when a light- sensing semiconductor device is applied to a photocoupler. CONSTITUTION:Array-shaped photodiodes 1 and two transistors 2 are provided in a chip, while bonding pads (3 to 6) are disposed at four corners of the chip, and they are connected by Al wirings 7. By changing the number of the photodiodes connected in parallel, the sensitivity of a light-sensing semiconductor device (the current transfer rate of a photo-coupler, accordingly, when the device is applied thereto) can be changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light receiving semiconductor device having a plurality of photodiodes arranged in a matrix, a method for manufacturing the same and an optical coupling device (photo coupler, photo interrupter, etc.) using the same.

[0002]

2. Description of the Related Art FIG. 7A is a plan view of a conventional light receiving semiconductor device used in an optical coupling device, and FIG. 7B is an equivalent circuit diagram thereof. In the conventional light receiving semiconductor device, as shown in the figure, one photodiode 1a and one transistor 2a are provided, and an output terminal 3, a power supply terminal 4, a spare terminal 5, and a GND are provided at four corners of the chip.
Bonding pads to be terminals 6 are arranged respectively,
These elements were connected to each terminal by an Al wiring 7.

In the conventional light-receiving semiconductor device, an epitaxial layer is formed on a substrate, and then the light-receiving semiconductor device shown in FIG.
Multiple photo repeaters (photolithography process,
It has been formed through a set of processes including an etching process, a diffusion process, and the like (hereinafter referred to as PR) process. That is, after forming an n-type epitaxial layer on a p-type substrate on which an n ⁺ buried layer is formed, if necessary, an element isolation PR for forming a p ⁺ type diffusion layer serving as an element isolation region, a collector extraction region, and Collector / phosphorus diffusion PR forming the cathode extraction region of the photodiode, boron diffusion PR forming the base region and anode region of the photodiode, emitter / phosphorus diffusion PR forming the emitter region, contact hole PR, Al wiring PR, bonding The steps of pad PR are executed.

In the optical coupling device, the current transfer ratio (Current Transfer Ratio:
In the conventional light receiving semiconductor device, the diffusion depth of the emitter region has been changed in order to respond to this. FIG. 8 is a graph showing the relationship between the diffusion time and the CTR in the emitter / phosphorus diffusion PR. The CTR varies almost linearly with diffusion time because the base width, and thus the transistor h _FE , varies with emitter diffusion time.

In the conventional manufacturing method, a wafer in which boron diffusion PR (base diffusion process) has been completed is held as an intermediate stock product, and when the CTR of the optical coupling device to be manufactured is determined, the emitter diffusion is performed accordingly. The light receiving semiconductor device having desired characteristics has been obtained by determining the time and performing the four PR steps after the emitter phosphorus PR.

[0006]

In the above-described conventional light receiving semiconductor device, at least four PR steps are required from the determination of the CTR of the photocoupler to the completion of the manufacture of the light receiving semiconductor device. There was a problem that it took a long time to get it. Further, since the conventional light receiving semiconductor device has only one photodiode and one transistor built therein, the light receiving circuit can be configured with only one circuit as shown in FIG. 7B. It was impossible for the product to meet a variety of uses.

[0007]

In a light receiving semiconductor device of the present invention, a plurality of light receiving elements are regularly arranged in a surface region of a semiconductor substrate, and a selected light receiving element among them is a transistor via a metal wiring. It was connected to.

In this light receiving semiconductor device, a transistor and a plurality of photodiodes in a regular array are formed in each chip, the surface of the substrate is covered with an insulating film, and a photolithography process for opening a contact hole is performed. After performing the above steps, a first step of storing the wafers subjected to the above-mentioned steps as an intermediate inventory product, and a photodiode to which wiring is to be provided from among the plurality of photodiodes according to the required characteristics of the product Al based on that decision
It is manufactured through the second step of forming wiring.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a plan view of a light receiving semiconductor device according to an embodiment of the present invention (however, Al wiring is not shown). As shown in the figure, a plurality of substantially square photodiodes 1 are formed in a regular array in the central part of the chip, and two transistors 2 are formed in the lower part of the chip.
Are formed. Bonding pads serving as an output terminal 3, a power supply terminal 4, a spare terminal 5 and a GND terminal 6 are arranged at the four corners of the chip.

FIG. 2A is an enlarged view of the photodiode portion of FIG. The photodiode 1 is formed by being separated and divided by the element separation region 10. An anode Al wiring 7a and a power Al wiring 7b are laid on the element isolation region 10, and these Al wirings are connected to the anode region and the cathode region of each photodiode.

FIG. 2B is a sectional view taken along line XY of FIG. As shown in FIG. 2B, an n-type epitaxial layer 9 is formed on the p-type substrate 8, and each photodiode 1 has an element isolation region (p ⁺ -type) penetrating the n-type epitaxial layer. It is formed so as to be surrounded by a diffusion layer 10. The n ⁺ type diffusion layer 11 which is the cathode extraction region of the photodiode is the power source Al wiring 7b.
Connected to p, which is the anode region of the photodiode
The type diffusion layer 12 is connected to the anode Al wiring 7a.

Next, a method of manufacturing the light receiving semiconductor device of this embodiment shown in FIG. 2 will be described with reference to the flow chart of FIG. An n ⁺ type buried layer (not shown) is selectively formed on the p type substrate 8 if necessary, and then an n type epitaxial layer 9 is grown. Next, element isolation PR
At this time, boron is ion-implanted at a high concentration to form the element isolation region 10, and in the collector / phosphorus diffusion PR, the collector lead-out region and the n ⁺ type diffusion layer 11 to be the cathode lead-out region of the photodiode are formed.

Next, in the boron diffusion PR, the p-type diffusion layer 12 to be the base region of the transistor and the anode region of the photodiode is formed, and in the subsequent emitter / phosphorus diffusion PR, the emitter region is formed. here,
An insulating film whose lower layer is an oxide film and whose upper layer is a nitride film is formed on the wafer, and a contact hole is formed in the nitride film in the contact hole PR. Then, it is stored as an intermediate stock item in this state.

In this light receiving semiconductor device, by changing the number of photodiodes connected in parallel, it is possible to change the sensitivity, and thus the CTR, when applied to an optical coupling device, in a substantially linear manner. Therefore, when the CTR of the optical coupling device in which this light receiving semiconductor device is used is determined, the number of photodiodes connected in parallel is determined, and the pattern of Al wiring to be formed is determined. Prior to the Al wiring PR, the oxide film in the contact hole is removed by etching, and Al is deposited on the entire surface by vapor deposition. In the Al wiring PR, the Al wirings 7a and 7b having the determined pattern
And bonding pads (terminals 3 to 6) are formed.
After covering the Al wiring with the insulating film, the insulating film on the bonding pad is removed by the bonding pad PR.

FIG. 4A is a plan view showing a wiring example of the present embodiment (however, the wiring of the photodiode portion is omitted, the same applies hereinafter), and FIG. 4B is an equivalent circuit diagram thereof. is there. This circuit has the same circuit form as the conventional light receiving circuit shown in FIG. However, the photodiode in the conventional example is a photodiode array in this embodiment.

FIG. 5A is a plan view showing another wiring example, and FIG. 5B is an equivalent circuit diagram thereof. In this embodiment, two power supply terminals are provided and the number of photodiodes connected to each power supply terminal is made different. According to this structure, after the light receiving semiconductor device is completed,
An appropriate circuit can be selected from among using the power supply terminal 4, using the spare terminal 5 as a power supply terminal, and connecting and using the terminal 4 and the terminal 5 according to the application.

FIG. 6A is a plan view showing another wiring example, and FIG. 6B is an equivalent circuit diagram thereof. In this circuit example, two parallel transistors and output terminals are connected to the two transistors,
Two light receiving circuits are configured. According to this structure of the light-receiving semiconductor device, one of the terminals 3 and 5 is used, two outputs are obtained from one optical coupling device, and the terminals 3 and 5 are connected in parallel to have a large current capacity. It is possible to use such as configuring the circuit of.

[0018]

As described above, the light-receiving semiconductor device of the present invention is provided with a plurality of photodiodes arranged in a matrix, and the number of the connected photodiodes can be changed by the Al wiring. According to the present invention, it is possible to manufacture a light-receiving semiconductor device having a required sensitivity simply by changing the pattern of the Al wiring PR. Therefore, according to the present invention, the wafer after the completion of the emitter diffusion is held as an intermediate stock product, and after the sensitivity request for each application such as CTR of the optical coupling device is made, the two P
The product can be provided only by executing the R process, and the TAT (turn around time) can be shortened as compared with the case of the conventional example.

Further, the sensitivity can be adjusted with higher precision as compared with the conventional example in which the emitter diffusion time is adjusted to manufacture a light receiving semiconductor device having a desired sensitivity. Further, since a plurality of transistors are provided on the same chip, according to the present invention, a plurality of light receiving circuits can be built in one light receiving semiconductor device, and it is possible to cope with various applications. Become.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of the present invention.

FIG. 2 is an enlarged view of a photodiode portion of FIG. 1 and a sectional view thereof.

FIG. 3 is a flowchart mainly showing a PR process in a manufacturing process.

FIG. 4 is a plan view showing an Al wiring example for the embodiment of FIG. 1 and its equivalent circuit diagram.

5A and 5B are a plan view and an equivalent circuit diagram showing an Al wiring example for the embodiment of FIG.

6 is a plan view showing an example of Al wiring for the embodiment of FIG. 1 and its equivalent circuit diagram. FIG.

FIG. 7 is a plan view of a conventional example and its equivalent circuit diagram.

FIG. 8 is a graph showing the relationship between emitter diffusion time and CTR.

[Explanation of symbols]

1, 1a Photodiode 2, 2a Transistor 3 Output terminal 4 Power supply terminal 5 Spare terminal 6 GND terminal 7 Al wiring 7a Anode Al wiring 7b Power supply Al wiring 8 p-type substrate 9 n-type epitaxial layer 10 Element isolation region 11 n ⁺ type Diffusion layer 12 p-type diffusion layer

Claims (6)

[Claims] 1. A light receiving semiconductor device in which a plurality of light receiving elements are regularly arranged in a surface region of a semiconductor substrate, and a selected light receiving element among them is connected to a transistor through a metal wiring. 2. A plurality of light-receiving elements arranged in a surface region of the semiconductor substrate in a regular array, transistors arranged in the surface region of the semiconductor substrate, and bonding pads arranged on the semiconductor substrate. And a light-receiving semiconductor device in which a light-receiving element selected from the light-receiving elements is connected to the transistor and the bonding pad in parallel by a metal wiring. 3. A plurality of light receiving elements arranged in a regular array in a surface region of a semiconductor substrate, at least two transistors arranged in a surface region of the semiconductor substrate, and a plurality of light receiving elements arranged on the semiconductor substrate. A plurality of bonding pads, wherein the first group of light receiving elements of the light receiving elements are connected to the first transistor and the first bonding pad in a parallel connection mode by metal wiring, The light receiving semiconductor device in which the second group of light receiving elements is connected to a second transistor different from the first transistor and the first bonding pad in a parallel connection mode by metal wiring. 4. A plurality of light-receiving elements arranged in a surface region of the semiconductor substrate in a regular array, transistors arranged in the surface region of the semiconductor substrate, and a plurality of bondings arranged on the semiconductor substrate. A pad, the first group of light receiving elements of the light receiving elements are connected to the transistor and the first bonding pad in a parallel connection by metal wiring, and the second group of the light receiving elements A light-receiving semiconductor device in which a group of light-receiving elements is connected to the transistor and a second bonding pad different from the first bonding pad in a parallel connection mode by metal wiring. 5. A transistor and a plurality of photodiodes in a regular array are formed in each chip, a substrate surface is covered with an insulating film, and a photolithography process for opening a contact hole is performed. The first step is to store the wafer that has undergone each process as an intermediate inventory product, and the photodiode to be wired is determined from the plurality of photodiodes according to the required product characteristics, and the determination is made. A second step of forming an Al wiring based on the above, and a method for manufacturing a light receiving semiconductor device, comprising: 6. A light emitting device, a plurality of light receiving devices arranged in a surface region of the semiconductor substrate in a regular array, transistors arranged in the surface region of the semiconductor substrate, and a transistor arranged on the semiconductor substrate. And a light-receiving semiconductor device in which the light-receiving element selected from the light-receiving elements is connected in parallel to the transistor and the bonding pad by metal wiring in the same container. An optical coupling device that is optically coupled and arranged.