JPH01259576A - Photoconductive light-receiving element - Google Patents

Abstract

PURPOSE:To obtain an element of planer construction suitable for integration and excellent in integration with an electron device such as an FET by providing the first crystal growth layer of the first conductive type, which is buried along the first groove part inner surface formed on a substrate with the second groove part and the second crystal growth layer of the second conductive type formed buried inside the second groove part. CONSTITUTION:The first crystal growth layer 6 doped with p-type (the first conductive type) impurities is buried inside the first recessed groove on a substrate 5 with a recessed boundary on the substrate 5. Further, the second recessed groove is provided on the first crystal growth layer 6 and the second crystal growth layer 7 on n-type (the second conductive type) inside this recessed groove part. Further, since the first crystal growth layer 6 and the second crystal growth layer 7 are formed so as to constitute the plane part of the substrate 5 so that the surface becomes plane. Thereby, a horizontal type light- receiving element of planer construction can be composed so that an integration property can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a photoconductive type light receiving element in which the resistance value of a conductor changes when it receives light, and a method for manufacturing the same. The present invention relates to a type semiconductor light receiving element.

[Conventional technology]

Semiconductor light-receiving elements are small and lightweight, and can follow changes in optical signals at high speed, so they are considered indispensable for optical communications and optical information processing. Recently, field effect transistors (F
There is a demand for integration with functional elements such as ET) and other electronic devices.

FIG. 4 shows a photoconductive type light receiving element having a coplanar electrode structure having a light receiving surface formed by mesa etching. The growth layer 1 of n-type InGaAs (which is not doped but has a low concentration of n-type) is made of p-type InGaAs.
It is formed on a substrate 2 made of P or the like, and on this growth layer 1, n-type electrodes 3a and 3b for signal extraction are formed.

Furthermore, a p-type electrode 4 made of AuZn or the like is formed at the bottom of the substrate 2.

According to this technique, by applying a bias in the opposite direction between the n-type electrodes 3a, 3b and the p-type electrode 4, the depletion layer at the pn junction is expanded, so that the growth layer 1 can be made to have a high resistance. Furthermore, holes with low mobility generated in the growth layer 1 when light is incident can be taken into the p-type electrode 4 (into the substrate 2), improving the high-speed characteristics of the light receiving element.

Therefore, the frequency band can be improved.

[Problem to be solved by the invention]

However, the photoconductive type light receiving element according to the prior art has a structure in which the electrode is formed on the back side of the substrate and has a step, so that the FE
It is not suitable for integration with electronic devices such as T.

Furthermore, when transistors and the like are formed on the same substrate, latch-up, punch-through, etc. occur. Therefore, similar problems occur with light receiving elements, making it difficult to integrate peripheral circuits, a plurality of light receiving elements, etc. on a single substrate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a photoconductive light-receiving element having a Brenna structure that is suitable for integration and is excellent in integration with electronic devices such as FETs.

Another object of the present invention is to provide a manufacturing method that can easily manufacture the photoconductive type light receiving element.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention provides a first groove that is embedded along the inner surface of a first groove formed in a high-resistance substrate;
A first crystal growth layer of a first conductivity type having a groove, a second crystal growth layer of a second conductivity type embedded in the second groove, and at least one crystal growth layer formed on the first crystal growth layer. It is characterized by being configured to include two first conductivity type electrodes and at least one pair of second conductivity type electrodes for signal extraction formed on the second crystal growth layer.

In addition, a first step of forming a first groove in a highly resistive substrate, burying a first crystal growth layer of a first conductivity type along the inner surface of the first groove, and further adding a second conductivity type crystal growth layer thereon. a second step of planarizing the substrate surface by embedding a second crystal growth layer; a third step of forming at least one first conductivity type electrode on the first crystal growth layer; and a fourth step of forming at least one pair of second conductivity type electrodes for signal extraction on the growth layer.

[Effect]

Since the present invention is configured as described above, it is possible to eliminate steps due to the planar structure of the first crystal growth layer and the second crystal growth layer formed on the substrate with a concave boundary. .

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a photoconductive light receiving element according to the present invention will be described below with reference to the accompanying drawings. In the description, the same elements are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1 shows an embodiment of a photoconductive type light receiving element according to the present invention. A first concave groove is provided in a substrate 5 made of InP or the like whose resistance has been made high by doping with Fe or the like. This concave groove contains InP or InGa doped with a p-type (first conductivity type) impurity such as Zn.
A first crystal growth layer 6 of As is embedded on the substrate 5 with a concave boundary. Further, the first crystal growth layer 6 is provided with a second concave groove, and the second concave groove is n'''' even if it is not doped (actually, it is undoped). ) n-type (second conductivity type) InGaAs
A second crystal growth layer 7 is formed. In addition, the above first
The crystal growth layer 6 and the second crystal growth layer 7 are formed so as to constitute a flat part of the 2iS plate 5, so the surfaces thereof are flat.

Further, on the first crystal growth layer 6, there is one p layer of AuZn, etc.
A type (first conductivity type) electrode 8 is formed, and a second crystal growth layer 7 is formed.
A pair of n-type (second conductivity type) electrodes 9a and 9b made of AuGeNi or the like are formed thereon.

According to this embodiment, since a bias voltage in the opposite direction is applied between the n-type electrode 8 and the n-type electrode 9a, the mobility of the electron-hole pairs generated by the incidence of light is The small holes are taken into the n-type electrode 8, improving the high-speed performance of the photoconductive light-receiving element and providing a wide frequency band.

Furthermore, since the surface is flat, integration is good, and the structure in which a crystal growth layer is embedded in a highly resistive substrate is excellent in terms of element isolation.

Next, a method for manufacturing a photoconductive type light receiving element will be explained based on FIG. 2. A silicon nitride film (SiN
) or a silicon oxide film (SiC2) 10 is formed by cyclotron resonance plasma or plasma CVD method (FIG. 2(b)). Furthermore, after a silicon nitride film (SiN) or a silicon oxide film (S i02 ) 10 is formed by a known photolithography technique, the substrate 5 is etched by anisotropic etching through this opening.
A first groove portion A is formed in (FIG. 2(C)).

In this first groove A, a first crystal growth layer 6 of InP or InGaAs doped with p-type (first conductivity type) impurities is formed.
is formed by forming a concave boundary on the substrate 5 by, for example, a molecular beam crystal growth method or a liquid phase growth method (see (d) in the same figure).
)). A second groove portion B is formed in this first crystal growth layer 6. In this case, the first crystal growth layer 6 is not formed on the nitride film (SiN) or the oxide film (S i02 ) 10.

Next, a silicon nitride film (SiN
) or the silicon oxide film (S x 02 ) 10 is removed once (see figure (e)), and a nitride film (SiN) or oxide film (S i02 ) is formed on the entire surface except for the second groove B.
(f) of the same figure), and the n-type (second
A second crystal growth layer 7 of InGaAs undoped with (conductivity type) impurities is formed with a concave boundary on the first crystal growth layer 6 by, for example, molecular beam crystal growth or liquid phase growth. .

Note that the second crystal growth layer 7 is not formed on the nitride film (SiN) or the oxide film (S i02 ) 10 (
Figure (g)). In this case, metal organic vapor phase epitaxy can be used as a method for forming the first crystal growth layer 6 and the second crystal growth layer 7. If this organometallic vapor phase epitaxy method is used, the steps shown in FIGS.
can be formed.

Thereafter, a nitride film (SiN) or an oxide film (Si02) formed on the substrate 5 and the first crystal growth layer 6 is removed.
) 10 is removed. The first crystal growth layer 6 and the second crystal growth layer 7 formed on the substrate 5 are formed on the same plane as the substrate 5, so the surface is flat (FIG. 2 (h)).
.

Next, at least a pair of n-type (second conductivity type) electrodes 9a, 9b are formed on the second crystal growth layer 7 in ohmic contact (FIG. 1(i)), and at least one p-type (first conductivity type) electrode type) electrode 8 is formed with ohmic contact (see figure (j)).
)).

FIG. 3 shows a modification of the embodiment shown in FIG.

In the following, we will particularly explain the points that differ from the embodiment shown in FIG.
Other structures, functions, etc. are substantially the same, so their explanation will be omitted.

In FIG. 3(a), the n-type electrodes 8a and 8b are the n-type electrode 9a,
They are arranged next to 9b. By applying a predetermined voltage to the n-type electrodes 8a, 8b, holes generated in the second crystal growth layer 7 formed under the n-type electrodes 9a, 9b can be taken in, thereby improving high speed.

FIG. 3(b) shows a pair of n-type electrodes 8a, 8 in a direction substantially perpendicular to the direction in which the n-type electrodes 9a, 8b are formed.
b.

The same figure (c) shows an n-type electrode 8 surrounding the n-type electrodes 9a, 9b and the second crystal growth layer 7 sandwiched between these n-type electrodes.
A, 8b, 8c, and 8d are arranged.

The figure (d) shows the n-type electrodes 8a and 8b in the figure (c).
, 8c, and 8d are integrated.

In addition, in FIG. 3(e), n-type electrodes 8a and 8b are configured in a U-shape and are arranged to face n-type electrodes 9a and 9b, respectively.

Furthermore, in FIG. 2(f), n-type electrodes 9a and 9b configured in a "U" shape are arranged so as to be sandwiched between n-type electrodes 8a and 8b.

Note that the substrate and crystal growth layer in this example are GaAs.
It can also be applied to grooves with an inverted mesa shape.

〔Effect of the invention〕

Since this invention is configured as explained above,
A horizontal light-receiving element can be constructed with a Brehner type structure, and integration efficiency can be improved.

Furthermore, since the structure has no steps, it is easy to integrate it with electronic devices such as FETs.

Furthermore, since a substrate with a high resistance, an insulating property, or a semi-insulating property can be used, it is advantageous in terms of element isolation.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the photoconductive type light receiving element according to the present invention, FIG. 2 is a cross-sectional view showing the structure of the photoconductive type light receiving element according to the present invention according to the manufacturing process, and FIG. 4 is a plan view showing a modified example of the photoconductive type light receiving element according to the present invention, and FIG. 4 is a sectional view showing a photoconductive type light receiving element according to the prior art. 1...Growth layer 2.5...Substrate 3...N-type electrode 4...P-type electrode 6...First crystal growth layer 7...Second crystal growth layer 8...p Type electrode 9...N type electrode (o) 5' (b) Photoconductive type light receiving element Figure 1 Prior art Figure 4

Claims (1)

[Claims] 1. A first crystal growth layer of a first conductivity type, which is embedded along the inner surface of a first groove formed in a high-resistance substrate and has a second groove; and the second groove. at least one first conductivity type electrode formed on the first crystal growth layer; and at least one first conductivity type electrode formed on the second crystal growth layer. and at least one pair of second conductivity type electrodes for signal extraction. 2. A first step of forming a first groove in a highly resistive substrate, burying a first crystal growth layer of a first conductivity type along the inner surface of the first groove, and further forming a second conductivity layer thereon. a second step of flattening the surface of the substrate by embedding a second crystal growth layer of a mold; a third step of forming at least one first conductivity type electrode on the first crystal growth layer; a fourth step of forming at least a pair of second conductivity type electrodes for signal extraction on the second crystal growth layer.