JPS61144888A - Photo receiver and photo electronic device incorporated with photo receiver - Google Patents

Abstract

PURPOSE:To make it possible to detect the light with its different wavelengths being simultaneously differenciated, by a method wherein photo receivers with wavelength selection layers and different arreas, and an optical fiber corresponding to them are positioned on the main surface of a semiconductor. CONSTITUTION:The incident laser light 8 on an optical fiber 4 fixed on a celamic sleeve 5 of a cap 2 irradiated itself on a photo-receiving sections 7 on the photo receiver 6, and its output is taken out through a lead 9 mounted on a stem 1, and a wire 11. On the other hand, the photo-receiver 6 consists of p type Ga1-xAlxAs layers 17-19 formed on a GaAs substrate 15 with the liquid phase epitaxial method. The crystalline mixing ratio of Al, (x) satisfies the relation of a<b<c (a=0, b=0.2, c=0.4, etc) and differs in its transmissing wavelength regions. Therefore, the light with different wavelength regions can be differenciated by the photo receiving sections 7.

Description

[Detailed Description of the Invention] [Technical Field] The present invention is a technology that is effective when applied to light reception technology, particularly wavelength division multiplex communication technology, and includes, for example, a light reception element in wavelength division multiplex communication, or a light reception element section of this kind. The present invention relates to an optoelectronic device incorporating a light receiving element such as an integrated optical device (OEIC element).

[Background technology]

Wavelength division multiplexing is known as one type of multiplexed transmission in optical fiber communications. The basic configuration of this wavelength division multiplexing transmission is a system in which a plurality of pieces of information are transmitted from a transmitting side to a receiving side through a single optical fiber, and each piece of information is transmitted as a plurality of pieces of optical information having mutually different wavelengths. Therefore, on the transmission side, a plurality of transmitters are arranged in multiple stages, and the optical signals emitted from each transmitter are sent to the main optical fiber for transmission via the optical fiber for connection. At this time, the optical fiber connected to the light emitting source is optically connected to the main optical fiber via an optical multiplexer.

Furthermore, on the receiving side, an optical demultiplexer is connected to the main optical fiber, and the optical demultiplexer demultiplexes the optical signal into wavelengths (other methods for demultiplexing include a method using a prism).

) to be done. Each optical signal demultiplexed by the optical demultiplexer is sent to a light receiving element connected to each receiver through an optical fiber connected to the optical demultiplexer. The optical signal is converted into an electrical signal by the light receiving element, and the information is transmitted to the receiver.

By the way, in the receiving system, the optical connection between each light receiving section and the main optical fiber is achieved by using an optical demultiplexer and an optical fiber connecting the optical demultiplexer and the light receiving element. There are many connection points, which hinders the reduction of optical loss. Further, the optical connection work is cumbersome;
Also, the large number of component parts hinders cost reduction.

On the other hand, Ga used in semiconductor lasers and light emitting diodes
Compound semiconductor materials such as AfLAs and InGaAsP are
When the component ratio of the constituent materials, that is, the mixed crystal ratio X changes, the energy gap (Eg) changes, and the wavelength (λ) changes. Materials J, April 1983 issue, published on April 1, 1983, pages 90 to 95.) In addition, the relationship between the wavelength of light (λ) and the energy gap (Eg) is given by the following equation. It will be done.

Eg Here, h is a blank constant and C is the speed of light.

In view of the above-mentioned circumstances, the present inventor realized that by providing each light receiving portion with a layer having a different mixed crystal ratio, it was possible to simultaneously identify and receive a plurality of lights having different wavelength ranges with a monolithic chip, and accomplished the present invention.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a light-receiving element that can simultaneously identify and receive a plurality of lights having different wavelength regions, and a photoelectronic device incorporating such a light-receiving element.

Another object of the present invention is to provide a receiving optoelectronic device for a wavelength division multiplexing transmission system with low optical loss.

Another object of the present invention is to provide a transmitting optoelectronic device for a wavelength division multiplexing transmission system that can reduce manufacturing costs.

The above and other objects and novel features of the present invention include:
It will become clear from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

That is, the monolithic light-receiving element of the present invention has a plurality of light-receiving parts, and a wavelength selection layer is provided on the main surface of each light-receiving part. Therefore, when this light-receiving element receives light having a plurality of wavelengths transmitted through one optical fiber, each light-receiving section can generate an electric signal corresponding to the light of the selected wavelength.

With the above configuration, a single connection between the optical fiber and the light-receiving element is sufficient for optical connection, and there are fewer optical axis alignment points than in the past, so optical loss can be reduced. Improved performance of wavelength division multiplexing transmission systems can be achieved. Further, as mentioned above, the manufacturing cost of the optoelectronic device can be reduced by reducing the number of optical connections, eliminating the conventionally required optical demultiplexer and connecting optical fiber, and reducing the number of parts.

〔Example〕

FIG. 1 shows an optical communication receiver (photoelectronic excess wavelength (nm)) in a wavelength division multiplexing transmission system according to an embodiment of the present invention.
FIG. 4 is a flowchart showing the manufacturing process of a light receiving element according to the present invention, FIG. 5 is a cross-sectional view showing the main part of a compound semiconductor board (wafer), and FIG. 6 is a diagram showing the relationship between Zn diffusion. FIG. 7 is a cross-sectional view showing the wafer after partially etching the A layer and the 8th layer;
FIG. 8 is a cross-sectional view of the wafer after isolated etching, and FIG. 9 is a cross-sectional view of the light-receiving element after electrode attachment.

The optical communication receiving device (optoelectronic device) for the wavelength division multiplexing transmission system in this embodiment has a structure as shown in FIG. In other words, the optical communication receiving device is
A metal plate-shaped stem 1 like Kovar and this stem 1
a puff cage 3 consisting of a cap 2 made of metal such as Kovar, which is airtightly attached to the main surface side of the puff cage by welding;
It consists of a ceramic sleeve 5 into which an optical fiber 4 protruding from the center of the cap 2 is fitted. Further, this device has a light receiving element 6 on the main surface (upper surface) of the stem 1, and the inner end of an optical fiber 4 fixed through the center of the cap 2 is provided on the light receiving surface (upper surface) of the light receiving element 6. It is a structure that faces. The light-receiving element 6 has a plurality of light-receiving sections 7 each disposed close to the light-receiving surface of the light-receiving element 6, as will be described in detail later, and has a single optical fiber 4.
It is designed to receive laser light 8 sent from.

On the other hand, four glue rods 9 are attached to the stem 1 in a perpendicular state to the stem 1. One of the leads 9 is fixed to the stem 1 in an electrically conductive state. The other three glues 9 each pass through the stem 1 and are insulatively fixed to the stem via an insulator 10 such as glass. The upper ends of these three through leads 9 are electrically connected to the electrodes of each light receiving portion 7 of the light receiving element 6 via wires 11, respectively.

On the other hand, the camp 2 has a cap-shaped structure having a flange 12, and the projection part 13 of the flange 12 is welded to the stem 1 and fixed airtightly.

In addition, a ceramic sleeve 5 is attached to the upper center of the cap 2.
is inserted into the ceramic sleeve 5, and an optical fiber 4 is inserted into the ceramic sleeve 5, and is fixed to the cap 2 by solder 14 injected into an insertion hole for the optical fiber 4 provided in the cap 2. The core diameter of the optical fiber 4 is 50 μm or less, but since the laser beam 8 emitted from the tip of the optical fiber 5 spreads, the main surface of the light receiving element 6 has a length and a width of about 100 μm. The entire area is irradiated with laser light 8. Therefore, as a matter of course, the laser light 8 is ensured to reach each of the light receiving sections 7 located at positions apart from each other.

Next, a method for manufacturing the light-receiving element 6 will be explained using the flowchart of FIG. 4 and the cross-sectional views of FIGS. 5 to 9.

The light receiving element 6 is manufactured according to the flow shown in FIG. That is, the light receiving element is manufactured through a multilayer epitaxial growth process, a diffusion layer formation process for electrode contact, a p-type A layer partial removal process, a p-type B layer partial removal process, an isolation etching process, an electrode formation process, a wafer backside etching process,
It is manufactured by sequentially performing a back electrode forming process and a chip forming process. When manufacturing the light receiving element 6, first a compound semiconductor substrate 15 as shown in FIG. 5 is prepared. This board 15
is an n-conducting type (n-type) QaA with a thickness of about 400 μm.
It is formed by s. Since the substrate 15 has a large diameter and is thin before being made into chips, the substrate 15 itself or the plurality of compound semiconductor layers formed on the main surface of the substrate 15 is generally called a wafer 16. ing.

Therefore, p conductivity type (p type) consisting of GaI-xAjLxAs (X is the mixed crystal ratio of AJIL) was sequentially formed on the main surface of the wafer 16 (substrate 15) by liquid phase epitaxial method.
Three compound semiconductor layers are formed, each having a thickness of about 0.2 to 0.6 μm. At this time, each layer is formed so that the mixed crystal ratio X of A1 is different from each other. The mixed crystal ratio X is selected to satisfy the relationship a < b < c. The mixed crystal ratios a, b, and c are, for example, a=o, b=0, if the recombination efficiency is not to be reduced.
2. c=0. 4th prize will be chosen.

As a result, the upper surface of the substrate 15 has a 0 layer 17.0 with a mixed crystal ratio X of C. is formed on this 0 layer 17 and has a mixed crystal ratio X of b
8 layers 18. An A layer 19 formed on this B1118 and having a mixed crystal ratio X of a is sequentially laminated.

These multi-layered epitaxial layers each have different mixed crystal ratios X and therefore have different transmission wavelength ranges.

That is, the relationship between the mixed crystal ratio X and the transmission wavelength region in G a I-X A jL +1 A S is as shown in the graph of FIG. 3. That is, in this graph, the upper region (hatched portion) of the curve is the transmission region at each wavelength and each mixed crystal ratio X. The mixed crystal ratio X of Ai is 0~
1, the transmission wavelength (λ) is approximately 880
It changes from nm to 500 nm.

Furthermore, when considering wavelengths in the relationship A>B>C, the mixed crystal ratio X that becomes the transmission limit for wavelength A is a, the mixed crystal ratio The mixed crystal ratio X, which is the wavelength transmission limit, is C.

Next, this wafer 16 is subjected to a process of forming a contact diffusion layer. That is, an insulating mask 20 made of 5i02 or the like is partially formed on the main surface of the wafer 16 by conventional photolithography. And wafer 16
A contact diffusion layer 21 made of a zinc diffusion layer is formed by ion implantation from the main surface of the contact diffusion layer 21 and subsequent annealing.
is partially formed. This contact diffusion layer 21 is formed to reach the 0 layer 17. However, this contact diffusion layer 21 is a layer provided for electrode contact, and does not reach the pn junction 29 formed by the 0 layer 17 and the substrate 15.

Thereafter, the mask 20 is removed.

Next, the A layer 1 is
9 and 8 layers 18 are partially removed.

That is, in FIG. 7, the A layer 19 is partially etched,
Further, a mask 22 made of an insulator such as a Si0g film is provided, and the eight layers 18 are partially etched. The etching is performed in a band-like manner in a direction perpendicular to the plane of the paper. The etchant used in the etching is sulfuric acid or phosphoric acid. Thereafter, the mask 22 is etched away.

As a result, not only the A layer 19 but also the 8th layer 18 and the 0th layer 1
7 is fully or partially exposed.

Next, by conventional photolithography, the wafer 16 is
An etching mask 23 made of a SiO2 film or the like is provided on the main surface, and isolation etching is performed. Also, the mask 23 is removed. As a result, the ABC island 24 consisting of only the 0 layer 17,
AB island 25 consisting of CJi 17 and 8 layers 18
．． A consisting of 0 layer F and 8 layer 18 and A layer 19
Islands 26 are respectively formed.

Next, as shown in FIG. 9 and FIG. 1 (numerals not shown), an electrode (anode electrode) 2 is placed on the main surface of each island.
7 is formed by a conventional lift-off method. That is, a photoresist (not shown) is deposited on the main surface area of the wafer 16 except for the area where the electrode 27 is formed, then an electrode forming material is deposited, and after the deposition, the photoresist is removed.

As a result, the electrode forming material in contact with the compound semiconductor layer remains as it is, but the electrode forming material on the photoresist is removed as the photoresist is removed, forming an electrode 27 as shown in FIG. The electrode is formed of, for example, a lower layer of Cr with a thickness of 1,000 to 2,000 people, and an upper layer of Au with a thickness of about 1 μm. Note that the anode electrode 27 is provided so as to overlap the region where the contact diffusion layer 21 is provided.

Next, the back side of the wafer 16 is etched, and the substrate 15 is etched.
The thickness is, for example, approximately several tens of μm to 100 μm. Furthermore, an electrode (cathode electrode) 28 is formed on the back surface of the wafer 16 by vapor deposition. Cathode electrode 28
For example, AuG-e Ni/Cr/A
The film is sequentially laminated with u, and is formed to have a total thickness of about 1 μm.

Thereafter, this wafer 16 is divided by scribing and subsequent cranking or dicing to form light-receiving elements 6 having a length and width of about 100 μm as shown in FIGS. 9 and 1.

Furthermore, this light receiving element 6, as shown in FIG.
It is mounted at a predetermined position on the main surface of the stem 1.

Further, the anode electrode 27 of each light receiving section 7 and the lead 9 fixedly fixed to the stem 1 are electrically connected by a wire 11. Furthermore, a camp 2 to which an optical fiber 4 is attached is hermetically fixed to the stem 1 to which the light receiving element 6 is fixed by welding. In this way, a receiving device for a wavelength division multiplexing transmission system is manufactured.

In such a receiving device, the laser beam 8 transmitted from the inner end of the optical fiber 4 by wavelength division multiplexing is received by a single (monolithic) light receiving element 6, and each light receiving part 7 of the light receiving element 6 receives the laser light 8. Transmission information for each wavelength in a predetermined region is converted into an electrical signal. That is, as shown in FIG. 2, in the ABC island 24, the lights of wavelengths A, B, and C reach the upper part of the pn junction 29 (indicated by a double line in the figure). is A
Since there is only 0 layer 17 where the mixed crystal ratio X of 1 is C, as can be seen from the graph in Figure 3, A, B,
All of the C laser beam 8 is transmitted and reaches the pn junction 29. In addition, the 0 layer 17 and AJ where the All mixed crystal ratio X is C
In the AB island 25 made up of eight layers 18 in which the mixed crystal ratio X of l is b, laser beams 8 of wavelengths A and B are similarly transmitted and reach the pn junction 29. Furthermore, A,1
The A island 26 consists of the 0 layer 17 where the mixed crystal ratio X of 1 is C, the 8 layer 18 where the mixed crystal ratio X of AfL is Then, the laser beam 8 with a single wavelength A is transmitted and pn
Junction 29 is reached. For example, an electric signal consisting of (and + base + Ω) from the electrode 27c on the ABC island 24, an electric signal consisting of (i + k) from the electrode 27b on the AB island 25, an electric signal consisting of (,L) from the electrode 27a on the A island 26 Assuming that a signal can be obtained, the signal corresponding to each wavelength can be obtained as follows.

(10 parties for i+) −(i+k)−Ω (i+k) −(t) =′, r−′− Therefore, the difference between the signals of the laser beams 8 in the wavelength ranges received by each light receiving section 7 is taken. 10 shows a top plan view of the light receiving element 6. As a result, it becomes possible to obtain a single signal of MtBtO, thereby achieving wavelength division multiplex transmission. FIG. 10 shows a top plan view of the light receiving element 6.

As shown in FIG. 10, in the light receiving element 6.

By making the light-receiving area of each light-receiving section 7at711r7o different, it is possible to improve the reliability of light reception of light of wavelengths with different sensitivities and wavelengths with different transmission coefficients. In other words, the light receiving sensitivity is low (or
The light receiving section 7a has a large light receiving area for wavelengths with low transmission coefficients, and the light receiving section 7a has a small light receiving area for wavelengths with high light receiving sensitivity (or high transmission coefficients).
b may be provided. 27 a, 27 b, 27
c indicates each anode electrode.

In addition, as shown in FIG. 11, a p-type layer 30.3 having a different mixed crystal ratio
If 1.32 is provided, the same effect as in the above embodiment can be obtained.

FIG. 12 shows a light receiving element 50 showing another embodiment of the present invention.
FIG.

The characteristic feature of this embodiment is that the anode electrode 51.
52.53 ohmic contact diffusion layer 54.5
5.56 does not come into contact with the pn junctions 57.5B and 59, the desired position of the n-type substrate 60 is a recess 61, 62, 63.

The reason for this structure is that in the structure shown in Figure 2,
0M64.8 layer 65 and A layer 66 on pn junctions 61 to 63
The total film thickness is 0. This is because, since the contact diffusion layers 54, 55, and 56 are thin and are as thin as 6 μm to 2°4 μm, even a slight change in the heat treatment conditions when forming the contact diffusion layers 54, 55, and 56 would destroy the pn junction.

In this embodiment, since the recesses 61, 62, and 63 are provided, the distance from the surface of the A layer 66 to the pn junctions 61, 62, and 63 is made long, and even if the formation conditions of the contact diffusion layer change somewhat, the pn Bonding failure does not occur, that is, an improvement in yield can be achieved. In the figure, 67 is a cathode electrode, 68 is a stem, 69 is a pansivation film such as SiO□ or phosphosilicate glass (PSG), and 70, 7
1°72 is a bonding wire.

〔effect〕

(1) The receiver of the present invention has a monolithic structure in which the built-in light-receiving element has a plurality of light-receiving parts, so it has a higher reliability compared to a receiver with a structure in which a plurality of light-receiving elements are assembled. The effect is that the

(2) Since the receiver of the present invention has a structure in which the tip of an optical fiber faces a light receiving element having a plurality of light receiving parts, optical fibers are used to connect the main optical fiber and each light receiving element. Compared to the conventional structure in which connections are made, the number of connection points is reduced, resulting in less optical coupling loss and improved performance.

(3) From the above (2), since the receiving device of the present invention has fewer parts, the receiving device can be made smaller and the installation area can be reduced.

(4) From the above (2), the receiving device of the present invention has the effect that maintenance is easy because the number of parts is reduced.

(5) From the above (2), since the receiving device of the present invention has fewer parts, the number of man-hours in its manufacture can be reduced, and therefore the manufacturing cost can be reduced.

(6) From the above (1), (21, and (41), according to the present invention, the effect of improving the reliability of the wavelength division multiplexing transmission system can be obtained.

(7) According to the above (1) to (6), the present invention provides a synergistic effect in that a compact receiving device with high performance and reliability can be provided at low cost.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor.

Furthermore, the same effects as in the above embodiments can be obtained even if Si, ternary and quaternary compound semiconductors, or the like are used to constitute the light-receiving element 6 of the present invention.

[Application field]

In the above explanation, the invention made by the present inventor was mainly applied to the manufacturing technology of a receiving device in a wavelength division multiplexing transmission system, which is the field of application that formed the background of the invention, but the invention is not limited to this. For example, it can be applied to measurement technology, medical technology, etc.

The present invention can be applied to manufacturing techniques for light receiving devices having a small number of wavelengths (at least a plurality of wavelengths).

[Brief explanation of drawings]

FIG. 1 is a perspective view of the main parts of an optical communication receiving device (optoelectronic device) in a wavelength division multiplexing transmission system according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing the reception principle, and FIG. 3 is an A ,1
1 is a graph showing the relationship between the mixed crystal ratio (x) and the transmission wavelength (nm). Figure 4 is a flowchart showing the manufacturing process of a light receiving element according to the present invention. Figure 5 is a diagram showing the main parts of a compound semiconductor board (wafer). Figure 6 is a cross-sectional view of the wafer after Zn diffusion, Figure 7 is a cross-sectional view of the wafer with the A and B layers partially etched, and Figure 8 is after isolated etching. Figure 9 is a cross-sectional view of the photodetector after electrode attachment, and the 1θth
The figure is a plan view of a light receiving element according to another embodiment of the present invention, FIG. 11 is a sectional view of a light receiving element according to still another embodiment of the present invention, and FIG. 12 is a plan view of a light receiving element according to still another embodiment of the present invention. FIG. 3 is a cross-sectional view of a light receiving element. DESCRIPTION OF SYMBOLS 1... Stem, 2... Cap, 3... Package, 4... Optical fiber, 5... Ceramic sleeve, 6... Light receiving element, 7... Light receiving part, 8... Laser light, 9... Lead, 10... Insulator, 11... Wire, 12... Flange, 13... Projection part, 14... Solder, 15... Board, 16...・
Wafer, 17...0 layer, I8...B layer, 19...
A layer, 20...mask, 21... contact diffusion layer, 22... mask, 23... mask, 24...
ABC Island, 25... AB Island, 26.
...A island, 27... Anode electrode, 28...
・Cathode electrode, 29... pn junction, 30.31.3
2...p-type layer, 50...light receiving element, 51, 52.5
3...Anode electrode, 54.55.56...Diffusion layer for ohmic contact, 57.58.59...p
n-junction, 60... n-type substrate, 61. 62. 63・
... recess, 64... 0 layer, 65... B layer, 66...
・A layer, 67... cathode electrode, 68... stem,
69... Vansivation film, 70.71.72...
・Bonding wire.

Claims (1)

[Scope of Claims] 1. A light-receiving element characterized by having a plurality of mutually independent light-receiving parts on a main surface of a semiconductor. 2. The light-receiving element according to claim 1, wherein the main surface of the light-receiving section is provided with a wavelength selection layer that determines a wavelength range for receiving light. 3. The light-receiving element according to claim 2, wherein the light-receiving areas of each of the light-receiving parts are different from each other. 4. The light receiving element according to claim 2, wherein the light receiving wavelength ranges in each of the wavelength selection layers are different from each other. 5. An optoelectronic device comprising a light receiving element having a plurality of mutually independent light receiving parts on the main surface of a compound semiconductor, and an optical fiber corresponding to the light receiving element. 6. The optoelectronic device according to claim 5, wherein the light receiving wavelength regions of the respective light receiving portions of the light receiving element are different from each other. 7. The optoelectronic device according to claim 6, wherein transmission information of a desired wavelength is selected from the wavelengths of light received by each light receiving section of the light receiving element.