JPH025489A - Semiconductor light receiving device - Google Patents

Abstract

PURPOSE:To suppress the occurrence of defect such as dislocation by providing a multiplier layer, which is a Si substrate, an insulating film mask having a circular opening formed on the substrate, and a light absorbing layer, formed of epitaxially grown compound semiconductor having a lattice constant larger than that of the Si, on the substrate within the opening. CONSTITUTION:An insulating film mask 2 having a circular opening 21 is formed on an Si substrate 1, and a light absorbing layer 3, which is a compound semiconductor, is epitaxially grown only on the substrate 1 portion within the opening 21. Thus, when the area of the opening 21 is decreased and the insulating film mask 2 including many openings is used, the outer peripheries of the epitaxial growth layer are dispersed and moreover the sum total of the lengths of the outer peripheries is increased so that release of interfacial stress is facilitated and occurrence of dislocation is decreased. In addition, the curvature of the epitaxial growth layer is also decreased: this is advantageous to subsequent processes.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a semiconductor light receiving device, and particularly to a semiconductor light receiving device in the 1 μm wavelength band.

The aim is to create a high-multiplying, low-noise semiconductor photodetector that suppresses the occurrence of defects such as dislocations.

A multiplication layer 1 of a Si substrate, an insulating film mask 2 having a circular opening 21 formed on the substrate, and a compound having a lattice constant larger than the lattice constant of Si on the substrate in the opening. The semiconductor light receiving device includes a light absorbing layer 3 formed by epitaxially growing a semiconductor.

[Industrial application field]

The present invention relates to a semiconductor light receiving device, and particularly to a semiconductor light receiving device in a 1 μm wavelength band.

BACKGROUND OF THE INVENTION As optical communications become longer distances and faster, there is a demand for semiconductor photodetectors that can be used in the 1 μm wavelength band and have low noise.

Therefore, it is necessary to develop a semiconductor light-receiving device that has a light absorption layer that absorbs light in the 1 μm wavelength band and a multiplication layer that has a large ionization rate ratio.

[Conventional technology]

Conventionally, as a semiconductor photodetector in the 1 μm wavelength band.

InP is used as a multiplication layer, and In, -XGaXAs (Ox
A semiconductor light-receiving device having a light absorption layer of <1) is known.

However, since InP has a small ionization rate ratio,
There is a limit to how low the noise can be reduced.

Therefore, in order to reduce noise, Si is used as a multiplication layer.

A structure with In, Ga, As (0<x Ri1) as a light absorption layer is considered, and In, GaXA on a Si substrate
Although attempts were made to grow s (O<X<1),
When epitaxially growing a light absorption layer of In, XGaXAs on a Si substrate (multiplier layer), Si and In, , x
Because of the large difference in lattice constant of GaXAs, as the thickness of the light absorption layer increases, internal stress accumulates and dislocations occur significantly, making it difficult to use a semiconductor light receiving device with such a structure.

[Problem to be solved by the invention]

In the present invention, Si is used as a multiplication layer, and In, -xGaXAs (
It is an object of the present invention to provide a semiconductor light-receiving device which has a structure in which a light absorbing layer is made of OxXx1) and which suppresses the occurrence of defects such as dislocations.

[Means for Solving the Problems] FIGS. 1(a) to 1(c) show cross-sectional views of a semiconductor light receiving device of the present invention. In Figures 1(a) to (c), 1 is S
i substrate (multiplier Ji), 2 is an insulating film mask, 21 is an opening, 3 is a light absorption layer, 4 is a graded layer, 5 is a strained superlattice, 6 is a window layer, 7 and 8 are electrodes .

FIGS. 2(a) and 2(b) show a top view and a cross-sectional view of the insulating film mask, respectively, and 2 is an insulating film mask;
1 represents an opening.

The above problem consists of a multiplication layer 1 made of a Si substrate, an insulating film mask 2 having a circular opening 21 formed on the substrate, and a lattice with a lattice constant larger than that of St on the substrate in the opening. This problem is solved by a semiconductor light receiving device including a light absorbing layer 3 formed by epitaxially growing a compound semiconductor having a constant constant.

2. In the semiconductor light receiving device of the present invention, between the multiplication layer 1 of the Si substrate and the light absorption layer 3 of the compound semiconductor, a gray compound semiconductor having a lattice constant greater than or equal to the lattice constant of Si and less than or equal to the lattice constant of the compound semiconductor is provided. A dead layer 4 or a strained superlattice 5 of a compound semiconductor may also be interposed.

[Effect]

In the present invention, an insulating film mask having a circular opening 21 is formed on the Si substrate 1, and the compound semiconductor of the light absorption layer 3 is epitaxially grown only on the substrate in the opening.

Usually, the lattice constant of the compound semiconductor of the light absorption layer is larger than that of St, and compressive internal stress acts on the epitaxially grown light absorption layer near the substrate.
When the substrate has a large area, the stress causes the epitaxially grown layer to have a large curvature. Moreover, the interfacial stress is not released until reaching the outer periphery of the epitaxially grown layer.

The occurrence of dislocations increases.

However, when using an insulating film mask 2 as shown in FIG. 2, which has a small area of the opening and has many such openings, the outer periphery of the epitaxial growth layer is dispersed, and the length of the outer periphery is Since the total amount increases, interfacial stress becomes easier to release and the occurrence of dislocations decreases. Furthermore, the curvature of the epitaxially grown layer is also reduced, which is advantageous for subsequent processes.

Furthermore, providing the opening of the mask with a slight taper and forming the upper part slightly wider also works to further reduce the absolute value of the residual stress in the epitaxially grown layer.

In addition, by forming the opening of the mask in a circular shape, the component of internal stress within the growth plane becomes isotropic, and local concentration of internal stress can be avoided.

When interposing a graded layer 4 having a lattice constant between the Si substrate (insulating layer) 1 and the light absorption layer 3 (
(Fig. 1(b)), or when a strained superlattice 5 is interposed (
In FIG. 1(C)), relaxation of internal stress is further promoted, and there is an even greater effect on preventing defects such as dislocations.

〔Example〕

As an embodiment of the present invention, the manufacturing process of a semiconductor light receiving device having the structure shown in FIG. 1(a) is shown in FIGS. 3(a) to 3(e). While referring to those diagrams.

The manufacturing process will be explained.

FIG. 3(a) A layer of 5000 μm thick S is placed on a Si substrate 1 with a reference thickness of 300 μm.
An insulating film mask 2 of iO2 or Si3N4 is formed by chemical vapor deposition (CVD).

Referring to FIG. 3(b), a resist with a thickness of 3,000 layers is applied to the entire surface, and an opening with a diameter of 80 μm is formed in the resist. At this time, in consideration of mass production, an insulating film mask having a plurality of rows and columns of openings vertically and horizontally is formed as shown in FIG.

After a plurality of semiconductor light receiving devices are completed at the same time, they are cut into dice and finally made into individual devices.

Referring to FIG. 3(C), the insulating film mask 2 is etched through the opening of the resist to form the opening 21. Then, as shown in FIG. By using an acid-based etchant and selecting etching conditions, a slightly tapered and wide opening is formed.

See Figure 3(d) triethyl gallium (TEG: Ga (Cz Hs) 3).

Trimethylindium (TMI: In(C)l:l)
3).

Metal-organic vapor phase epitaxy (MOVP) using arsine (hesHco) as a source
E) was grown at 650°C for 1 hour to a thickness of 3 pm.
Optical absorption N3 of In, GaXAs (X = 0.47)
form.

See Figure 3(e) Trimethylindium (TMI: In(C)+3)
3).

Using phosphine (PH3) as a source, an InP window N6 having a thickness of 2 μm is formed by metal organic vapor phase epitaxy.

An electrode 7 on top of the window layer. and an electrode 8 under the substrate.
form.

Si and the light absorption layer of In, Ga, As (x = 0.
The lattice constant of 47) is as follows.

St 5.43 people Inl4GaxAs (x = 0.47) 5.87
Second grade diffused layer In, Ga, As (x<z<1) 2 μ
Even if there is such a difference in lattice constants, the structure of this embodiment suppresses the occurrence of defects such as dislocations.

As another example, the manufacturing process of the structure shown in FIG. 1(b) will be described.

In the manufacturing process, the following process is added in the middle of the manufacturing process of the above-described embodiment.

That is, In, -xGa,
Before growing the light absorption layer 3 of As (x = 0.47), a first graded layer 41 and a second graded layer 42 are successively grown as the graded layer 4 by metal organic vapor phase epitaxy. At this time, the supply amounts of various source gases are controlled so that the composition of the epitaxially grown layer changes continuously. The composition and thickness of each layer are as follows.

First graded layer GaAs+-, Py (O<y<1) 2pm
The lower surface (y=1) of the first graded layer is GaP,
Its lattice constant (5,45) is the lattice constant of St (5,4
3), and the lattice constant increases continuously upwards from there.

The composition of the lower surface (z=1) of the second grade-defied layer is Ga.
As, this is the top surface of the first graded layer (y=o
), the light absorption layer 3 is formed upward from there.
The composition In, -xGaXAs (x = 0.47) transitions continuously. And the lattice constant is also In, -xGa
, with a lattice constant of As (x = 0.47) (5,87 people).

In this case, since the lattice constant shifts almost continuously from the substrate 1 to the light absorbing layer N3, the internal stress in the light absorbing layer is naturally relaxed, and the generation of defects such as dislocations is suppressed.

As yet another example, the manufacturing process of the structure shown in FIG. 1(C) will be described.

A strained superlattice 5 is formed by stacking a 100 μm thick superlattice layer 51 and a 100 μm thick superlattice layer 52 30 times in place of the graded layer described above.

51, In,-,GaVAs,-,MP, (v =
0.46. w=0) Internal strain due to the difference in lattice constant between the substrate 1 and the light absorbing layer N3 is absorbed by the superlattice, and the occurrence of dislocations and the like in the light absorbing layer is extremely reduced.

In this way, a 1 μm band semiconductor photodetector with extremely low noise can be realized.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to realize a semiconductor photodetector device having a Si substrate as a multiplier layer and a light absorbing layer with very few defects such as dislocations on top of the multiplier layer.
A semiconductor light receiving device in the μm wavelength band can be provided.

The present invention greatly contributes to increasing the distance and speed of optical communications.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a semiconductor light receiving device of the present invention. Figure 2 shows an insulating film mask. Figure 3 shows the manufacturing process. It is. In fig. 1 is a Si substrate (multiplier layer). 2 is an insulating film mask. 21 is an opening. 22 is resist. 3 is a light absorption layer. 4 is graded tier. 5 is a strained superlattice. 6 is the window layer. 7 and 8 are electrodes (σp AFDQ semiconductor receiving equipment price chart Figure 1 Kigaku family moon thorn mask Figure 2 (a) (b) (the law of nature Manufacturing process Figure 3 (zo f) 1) (Jji Manufacturing process Easy figure (Zono 2)

Claims (1)

[Scope of Claims] A multiplication layer (1) of a Si substrate, an insulating film mask (2) having a circular aperture (21) formed on the substrate, and an insulating film mask (2) formed on the substrate in the aperture. and a light absorption layer (3) epitaxially grown from a compound semiconductor having a lattice constant larger than that of Si.