JPS58170077A - Semiconductor photodetector - Google Patents

Abstract

PURPOSE:To form a photodetector which has high reliability and high sensitivity necessary for a light communication by forming a planar structure that an FET and a monolithic photodiode formed at the outside of the FET region are formed in an isolation region. CONSTITUTION:A photodiode section is manufactured by forming a cadmium (Cd) implantation p type layer 8 on an n type InP layer 7. When infrared ray, for example, of 1.55mum as a light transmission signal is absorbed by a light absorbing layer in a photodiode having a band gap adapted to receive the infrared light 12 of 1.55mum, i.e., the p type layer 8 and an n type InGaAs layer 2, electron-hole pairs are immediately generated, and a voltage is applied in advance in reverse direction. Accordingly, holes H are moved toward the negative electrode direction at upper side. Thus, a voltage is generated in the photodiode. Since the gate G in a J-FET and the photodiode are connected, the output voltage of the J-FET can be controlled by the voltage produced by the light transmission signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a light-receiving element for optical communication, and particularly to a semiconductor light-receiving device with high sensitivity in the 1 μm wavelength band.

(2) Background of the technology In recent years, as the information society has become more sophisticated, there has been an increasing demand for increased information processing volume and high-speed processing.

Therefore, conventional wired and wireless communication systems have limitations and cannot meet the above-mentioned requirements.

- Development of lasers, which are coherent light sources for optical communication systems that extend beyond the conventional electromagnetic wave region, from the far infrared region to visible light, and corresponding optical fibers and other optical circuit elements for optical communications. It is now at the stage of practical application. Furthermore, optical communications do not require expensive and important copper wires, and are desired from the standpoint of resource and energy conservation.

Against this background, even lower loss is needed in this optical communication area.

+I4i There are increasing technical demands such as All rate 1 and low cost.

(3) Prior art and problems A conventional monolithic photodiode and PET (field effect transistor) photodetector uses a semi-insulating substrate, on which isolation between each element is provided by a mesa structure, and Each electrode was configured.

However, in this type of mesa type device, photodiode 1 and F
It is difficult to connect between ET by wiring within the element, and there are also problems such as an increase in the number of lead terminals to external terminals.

Additionally, mesa-type structures have difficulties in passivation (surface stabilization). In other words, as mentioned above, the commonly used mesa-type phototransistor and FET optical communication light receiving device suffers from production technology-1 problems such as complicated wiring due to structural reasons and circuit characteristics. There were problems in terms of limitations and stability and reliability in use.

Furthermore, P-type FETs have the disadvantage that high-speed response cannot be obtained because of the small mobility of holes.

(4) Object of the Invention An object of the present invention is to provide a highly reliable and highly sensitive light receiving device necessary for optical communication by using a planar type structure of this type of light receiving element.

(5) Structure of the Invention The present invention is characterized in that it has an N-type multilayer on an N-type semiconductor substrate, and after forming a P-type buried layer in a certain area of the N-type semiconductor substrate, an N-type layer is formed. In a wafer in which a P-type layer is formed so that a part of the N-type region facing the previously formed P-type buried layer is isolated, an FET is placed inside the isolation region, and an FET is placed outside this region. It is a semiconductor light receiving device with a planar structure in which a monolithic photodiode is formed.

(6) Examples of the invention An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 (a+ to (fl) are process diagrams showing a method of manufacturing a semiconductor light receiving device of the present invention.

A liquid-phase Evita-kinyal (
1,1) E) method or vapor phase epitaxial (VPL',
) method with a thickness of 3 to 5 cm at a concentration of I
The N--1nGaAs (P) layer 2 is made to have a thickness of about .mu.m. ((a) of the same figure) Next, in order to diffuse Cd into the region where the FET will be formed in a later step, for example, a photoresist 4 is thinly applied and silicon nitride (Si:+Na) 5 is used as a mask to perform ultraviolet light 3. First, holes are made by photolithography according to the same figure (bl), and then, for example, 50 mm.
Selective diffusion is carried out in a gas atmosphere containing impurities of cadmium (Cd) for one hour at 0''C, and then the photoresist 4 and silicon nitride (Si2N4) 5 are removed to form a buried layer 6.

Furthermore, by liquid phase epitaxial (L P E) method or vapor phase epitaxial (V P E) method, N-In
A P layer or N-1nGaAs (P) layer 7 is grown to a thickness of about 2 μm. (Same figure (C)) Next, using the same selective diffusion technique as described above, cadmium was diffused in a gas atmosphere containing cadmium (Cd) impurities at about 500°C for about 3 hours, and the photodiode Diffusion is performed in the isolation section 9. (Figure (d)
) After that, Kadmira J is placed again in the center of isolation section 9.
, (Cd) diffusion for about 1.5 hours in a gas atmosphere at 500° C. to form the gate portion (G) 10.

((e) in the same figure) Finally, the A-to-da diode section 8 and the gate section (G) 10.
is formed by A u /Z n, and the back side 11 of the substrate of the photodiode, the source part (S), and the drain part (D) are formed by A u /G (3) to form an ohmic contact.

(Same figure (')) Then, the photodiode and gate (G
) are connected by metal wiring.

With the above, the light receiving device can be configured as a planar type, and
A double FET can form an N-channel.

FIG. 2 is an explanatory diagram showing the operation of a J, F, and ET type semiconductor light receiving device, which is an embodiment of the present invention.

The photodiode 1 part has cadmium (C) on the N-1nP layer 7.
d) Fabrication by forming an implanted P-type layer 8.

A light absorbing layer, that is, a P type [8 and N-1n G
As soon as the 1.55 um infrared light is absorbed in the a As layer 2, electron-hole pairs are generated, and since the biasing voltage is applied in the opposite direction, the holes 11 are directed toward the negative electrode. Move to. Therefore, a voltage is generated across the photodiode. Furthermore, since the gate section CG) passing through the JFET and the photodiode are connected, the output voltage of the JPET can be controlled by the voltage generated by the optical transmission signal.

Note that (7) above, JFET is formed by the P-type diffusion region 13.13 and the buried layer 6, that is, the P-type diffusion region, provided in advance on the top of the N-1n-GaAs layer 2, which is a feature of the present invention. Source part (S) and drain part (D
) forms an isolated island at N-1nPjii7,
However, in the JFET, it has become possible to form an N channel in the cap layer made of N-1nP layer 7. However, for the infrared light 12 transmitted by the optical transmission signal, a voltage is generated in the photodiode and applied to the gate part (G), causing a drain current (1o) from the source part (S) to the train part (D). ) can be modulated.

As described above, in the embodiment of the present invention, the P-type diffusion region, that is, the photodiode light receiving section 8 and the isolation section 9.9, are formed by Cd diffusion. Since the layer 6 rises, it is possible even if it does not reach the N-.InGaAs layer 2, that is, it can be formed in contact with and separated from the layer 2.

The same figure (bl is the above semiconductor light receiving device viewed from above)
ili figure T near 6° light 9' Io-F (!
: JFF, TiJ:, are connected within the element by two-one electrodes 14 as shown in the figure.

In the following, we have described the case where N-1nP is used as a substrate, but as shown in Figure 3, N-type gallium antimony (N-G
It is also possible to create the same structure using a substrate made of aSb) and a light absorption layer made of GaSb or GaSb.

In addition, in Fig. 3, the substrate N''''-〇aA S
15, for example, N--GaSb 16 and N--G
a A I S b layer 17 is formed, and the N--Ga
(AI) A buried layer 6' is provided on the top of the Sbbl 6, and an optical guide portion 8 is provided in the N-CaAlSb layer 17.
and an isolation region 9' is formed ζ).

(7) Effects of the Invention As mentioned above, the present invention improves productivity and stability due to the adoption of a complicated structure, which is a disadvantage of the mesa-type light receiving element using a P-type Ir conductor that has been generally used in the past.

By adopting a planar structure using an N-type semiconductor, the structure becomes simpler, which improves productivity, facilitates bashing, and solves problems such as reliability and reliability, which are problems of this type of equipment. The degree was in the direction of f. Furthermore, by using an N-type FET (field effect transistor), the photosensitivity and response speed are improved.

In general, in this type of compound semiconductor, it is easy to obtain an N-type, and it is advantageous in terms of manufacturing if an FET can be formed as an N-type, and because it is an N-type, it has characteristics such as high-speed response due to large electron mobility. .

Furthermore, by separating the channel layer N-rnF' from others by relatively easy P-type diffusion, F ti
T can constitute an N-type channel, and accordingly a large mutual conductance can be achieved, and the desired semiconductor light-receiving device has the effect of achieving higher performance.

[Brief explanation of drawings]

Figures ta+ to () are manufacturing process diagrams of the semiconductor light-receiving element of the present invention, Figure 2 is an explanatory diagram showing the operation of the semiconductor light-receiving element of the present invention, and Figure 3 is another embodiment of the present invention. 1...Substrate, 6.6'...Buried layer, 7...
Cap layer, 8, 8'... Light receiving part of photodiode, 9,9'... Separation layer, 14... Gate electrode, 17... Camp layer.

Claims (1)

[Claims] An N-type multi-layer is formed on an N-type semiconductor substrate, and after forming a P-type buried layer in one of the regions, an N-type layer is further formed, and a part facing the previously formed P-type buried layer is formed. P surrounding the N-type region so that the N-type region is isolated
1. A semiconductor light-receiving device having a planar structure, characterized in that a band region is formed, an FET is formed inside the isolated N-type region, and a photodiode is formed outside this region.