JPH0382085A - Semiconductor photodetector and manufacture thereof - Google Patents

Abstract

PURPOSE:To realize a pn junction having a sharp concentration distribution in a junction face with satisfactory reproducibility by forming a pn junction in a boundary in which a p-type impurity implanted layer is brought into contact with an n-type impurity implanted layer. CONSTITUTION:An n<-> type InGaAs light absorption layer 12, an n<-> type InGaAsP intermediate layer 14 are formed on an n-type InP substrate 10, and an n<-> type InP layer 16 is formed on the layer 14. Further, an n-type impurity implanted layer 18 in which an n-type impurity such as Si, etc., is ion-implanted is formed under the layer 15, and a p-type impurity implanted layer 19 in which a p-type impurity such as Mg, etc., is ion-implanted is formed in contact with the layer 18. A pn junction is formed of the layers 19, 18. The layer 19 is continued to a p-type impurity diffused region 22 formed on the top.

Description

[Detailed Description of the Invention] [Summary] A semiconductor light-receiving device and its manufacturing method, especially Inp/InGaA with InGaAs as a light absorption layer and InP as a multiplication layer.
Regarding an avalanche photodiode and a method for manufacturing the same, the purpose of the present invention is to provide a semiconductor light-receiving device having a pn junction with a steep concentration distribution at the junction surface and a device structure with high manufacturing reproducibility, and a method for manufacturing the same. Type I rxGaA
n-type 1 nGaAs between the s light absorption layer and the n-type InP layer
In the semiconductor light-receiving element in which a P intermediate layer is provided and an n-type impurity diffusion region is provided on the surface of the n-type InP layer, the n-type I
A P-type impurity implantation layer formed by ion-implanting a P-type impurity under the n-type impurity diffusion region in rhPjl;
An n-type impurity implantation layer formed by ion-implanting an n-type impurity under the type impurity implantation layer, and configured to form a pn junction at the interface where the n-type impurity implantation layer and the n-type impurity implantation layer contact. [Industrial Field of Application] The present invention relates to a semiconductor photodetector and a method for manufacturing the same, particularly an I n
What about GaAs as a light absorption layer and InP as a multiplication layer? InP/
The present invention relates to an InGaAs avalanche photodiode and a method for manufacturing the same.

[Prior Art] In recent years, we have reached the stage where the practical application of ultra-high-speed systems of several gigabits/second at a wavelength of 1 to 3 μm or 1.55 μm is being considered. For such ultra-high-speed systems, a semiconductor light-receiving element that is highly sensitive and capable of high-speed response is required. Among currently available semiconductor photodetectors, an InP/InGaAs avalanche positive photodiode with an InGaAs light absorption layer and an InP multiplication layer is expected to have the highest sensitivity and the fastest response.

FIG. 4 shows a semiconductor light receiving element which is a conventional InP/InGaAs avalanche photodiode.

n-type InGaAs formed on n-type InP substrate 10
n-type InG between the light absorption layer 12 and the n-type InP layer 16
An aAsP intermediate layer 14 is formed. An n-type impurity implantation layer 18 is formed in which n-type impurities such as 81 out of 6 in one n-type InP layer are implanted. A ring-shaped guard ring 20 formed by Be ion implantation and a P-type impurity diffusion region 22 formed by thermally diffusing Cd into the light receiving portion are formed on the surface of the n-type InP 116. This n-type impurity diffusion region 22 and the n-type impurity injection layer 18 form a ρn junction. A multiplication region is formed between the n-type impurity implantation layer 18 and the hp-type impurity diffusion fi region 22.

Ti
/ P t / A u PE pole 26 is formed, n,
jlJInP substrate] On the back surface of O, nt% 28 of A u/G e is formed.

Generally, InP/InGaAs avalanche photodiodes have a B[(Gain BandwidthM)
There are bandwidth limitations due to That is, if an attempt is made to increase the multiplication factor, which is the gain, the frequency band that can respond will decrease. For InP/InGaAs avalanche photodiodes, the GB product is typically 30-50GH2;
When used in an ultrahigh-speed system of several gigabits/second, an element structure that has a larger GB product and is easy to reproduce in manufacturing is required.

[Problem to be solved by the invention] As mentioned above, the conventional InP/InGaA shown in FIG.
In the s-avalanche photodiode, one n-type impurity diffusion region 22 forming a pn junction is formed by thermal diffusion of n-type impurities. However, thermal diffusion has a problem in that it is difficult to form a stable pn junction because precise depth control cannot be performed. Also, good p
In order to form an n-junction and secure a large GB product, a steep concentration profile with no tail is required, but it is difficult to form such a concentration profile with impurity diffusion. There was a problem.

The present invention has been made in consideration of the above circumstances, and it is an object of the present invention to provide a semiconductor light-receiving device having a pn junction with a steep concentration distribution at the junction surface and a device structure with high manufacturing reproducibility, and a method for manufacturing the same. purpose.

[Means to solve flB] The above purpose is to reduce n-type I nGaAs light absorption and nlIrx.
An n-type InGaAsP intermediate layer is provided between the P layers, and the n-type InGaAsP intermediate layer is provided between the P layers.
In a semiconductor light-receiving element in which a P-type impurity diffusion region is provided on the surface of an In1 layer, a P
type impurity implantation M, and an n-type impurity implantation layer formed by ion-implanting an n-type impurity under the P-type impurity implantation layer, and at an interface where the n-type impurity implantation layer and the n-type impurity implantation layer contact. This is achieved by a semiconductor light-receiving element characterized by forming a pn junction.

Moreover, the above purpose is to form n-type InGaA on an n-type InP substrate.
a step of epitaxially growing an s-light absorption layer, an n-type InGaAsP intermediate layer, and a first n-type In1 layer;
ion-implanting n-type impurities into the n-type In1 layer to form an n-type impurity implantation layer, and ion-implanting p-type impurities to form a p-type impurity implantation layer on the n-type impurity implantation layer; , a second n-type IrhPl on the first n-type IrhPl
It is characterized by comprising a step of epitaxially growing an n1 layer, and a step of diffusing a p-type impurity into the surface of the second n-type InP layer to form a p-type impurity diffusion region continuous to the n-type impurity implantation layer. This is achieved by a method of manufacturing a semiconductor light receiving element.

[Operation] According to the present invention, since the impurity layers forming the pn junction are both formed by ion implantation, a pn junction with a steep concentration distribution at the junction surface can be realized with good reproducibility.

[Example] A semiconductor light receiving element according to an example of the present invention will be described with reference to FIG. The same components in the conventional semiconductor light-receiving element ε shown in FIG. 4 are given the same reference numerals to omit or simplify the explanation.

On the nffJInP substrate 10, there is an n-type InGaAsGaA film with a thickness of about 2 μm and an impurity concentration of 5×10”am-”.
It has two light absorption layers. n-type I nGaAsGaA
The light absorption layer 2 has a thickness of about 0.5 μm and an impurity concentration of 5.
n-type I nGaAsP intermediate [1
4 is formed, and further an n-type InGaAsP intermediate layer 14 is formed.
An n-type InP layer 16 with a thickness of about 2 μm and an impurity concentration of 5×10” am is formed thereon.
The nGaAsP intermediate layer 14 has an energy gap Eg=
It is desirable that it be 0°9 to 1.2e■.

Furthermore, an n-type impurity implantation layer 18 in which Ω-type impurities such as SN are ion-implanted is formed under the n-type InP layer 16.
In contact with this n-type impurity implantation layer 18, a P-type impurity implantation layer 19 is formed by ion-implanting a P-type impurity such as Mg. These P-type impurity implantation layers 19 and n-type impurity implantation NJ
A pn junction is formed by is. Note that the P-type impurity implantation layer 19 has a P-type impurity diffusion region 22 formed thereon.
It is continuous.

FIG. 2 shows the concentration distribution on the aa' plane of the semiconductor photodetector shown in FIG. 1. The horizontal axis is the depth, and the vertical axis is the impurity concentration 1ρ.
Set to 1. Against a background with an impurity concentration of about 5XIQ "crn-", the n-type impurity implantation layer 19 is continuous in the tail part of the relatively gentle concentration distribution of the P-type impurity diffusion region 22, and further n-type impurity The injection layer 19 and the n-type impurity injection layer 18 are in contact with each other with a steep concentration distribution.

Since both the P-type impurity implantation layer 19 and the N-type impurity implantation layer 18 are formed by ion-implanting impurities,
As shown in FIG. 2, the p-type and n-type impurity concentration distributions are steep, and a good pn junction can be achieved.

As described above, since the present embodiment is formed by the nine n-type impurity implantation layers and the n-type impurity implantation layer, a good pn junction with a steep concentration distribution can be realized.

Next, a method for manufacturing the semiconductor light-receiving device of this example will be explained using FIG. 3.

First, a 2 μm thick layer of InGa is deposited on the n-type InP substrate 10.
As light absorption layer 12.0.5 horn thick n-type 1 nG
aA White P middle white layer As soon as the intermediate layer 14 is taxially grown, n-' type InP is grown on the n-type NnGaAsP intermediate layer As.
The layer 16a is epitaxially grown by 0.5 .mu.rn to complete the 14-thick growth (FIG. 3(a)).

Next, 81 ions were applied from the surface at 300 keV and at a dose of i2.
Ion implantation was performed under the conditions of ~4 x l 012 / cm 2 to form an n-type impurity implantation layer 1 in the n-type InP layer 16a.
form 8. Subsequently, Mg ions are implanted under the conditions of 100 keV and a dose of lXl0''/am2 to form an n-type impurity implantation layer 19 on the surface of the n-type InP layer 16a so as to be in contact with the n-type impurity implantation layer 18 (third Figure (b))
.

Next, the n-type InP layer 16 is placed on the n-type InP layer 16a.
The remaining 1.5 μm thick n''' type InP layer 16b is epitaxially grown (24-row growth) (FIG. 3(C)).
.

Next, the n-type InP layer 1 layer 6 surface e is diffused to form a ring-shaped guard ring 20, and the light receiving part is covered with Cd.
An n-type impurity diffusion region 22 is formed so as to be continuous with the n-type impurity implantation layer 19. Next, n-type InP
T I / P t through the protective film 24 on layer 1 and layer 6
/ A u's p@ pole 26 is formed, and the n-type InP substrate 10
An A u/G e n-electrode fli 28 is formed on the back surface of the semiconductor light receiving element to complete the semiconductor light receiving element (FIG. 3(d)).

In this example, since the n-type impurity implantation layer and the nW impurity implantation layer constituting the pn junction are formed by ion implantation, the implantation depth and impurity concentration can be precisely controlled, and the It is possible to dramatically improve the uniformity of the increased fΔ region between the layers and achieve a high yield.

Moreover, since the concentration distribution of the pn junction can be steepened to narrow the width of the multiplication region, it is possible to realize a semiconductor light-receiving device with a G6 product of 50 GHz or more. Furthermore, since the impurity region on the light-receiving surface is formed by mature diffusion rather than ion implantation, the surface is not damaged and leakage current can be prevented.

The present invention is not limited to the above embodiments, and various modifications are possible6.
For example, in the above embodiment, Sl was used as the n-type impurity to be ion-implanted, but other n-type impurities may also be used.
Mg was used as the type impurity, but other n such as Cd and Zn
Type impurities may also be used.

[Effects of the Invention] As described above, according to the present invention, since the impurity layer constituting the pn junction is formed by ion implantation, it is possible to realize a pn junction with a steep concentration distribution at the junction surface. Since the Th concentration can be precisely controlled, the uniformity of the multiplication region within a wafer and between wafers can be dramatically improved, and a high yield can be achieved.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a semiconductor photodetector according to an embodiment of the present invention, and Fig. 2 is a cross-sectional view of the semiconductor photodetector according to an embodiment of the present invention. l! ! A graph showing the concentration distribution, FIG. 3 is a cross-sectional view of the process for manufacturing the same semiconductor light-receiving element, and FIG. 4 is a cross-sectional view of a conventional semiconductor light-receiving element. In the figure, 10...-''n-type 1rhP substrate 12...n-type InGaAs light absorption layer t4-=
n-type In nGaAsP intermediate layer 16 --- n-type In
P layer 18...n type impurity injection layer 19...n type impurity injection layer 20...guard ring 22...n type impurity diffusion region 24...protective film 26...P electrode 28...・rxt&

Claims (1)

[Claims] 1. In a semiconductor light-receiving element in which an n-type InGaAsP intermediate layer is provided between an n-type InGaAs light absorption layer and an n-type InP layer, and a p-type impurity diffusion region is provided on the surface of the n-type InP layer. , a p-type impurity implantation layer formed by ion-implanting a p-type impurity under the p-type impurity diffusion region in the n-type InP layer; and a p-type impurity implantation layer formed by ion-implanting an n-type impurity under the p-type impurity implantation layer. 1. A semiconductor light-receiving device comprising: an n-type impurity implanted layer; and a pn junction is formed at an interface where the p-type impurity implanted layer and the n-type impurity implanted layer contact. 2. n-type InGaAs light absorption layer on n-type InP substrate, n
A step of epitaxially growing an InGaAsP intermediate layer and a first n-type InP layer, ion-implanting an n-type impurity into the first n-type InP layer to form an n-type impurity implantation layer, and ion-implanting a p-type impurity. forming a P-type impurity implantation layer on the n-type impurity implantation layer by implanting; epitaxially growing a second n-type InP layer on the first n-type InP layer; 1. A method for manufacturing a semiconductor light-receiving device, comprising the step of diffusing p-type impurities into a surface of an InP layer to form a p-type impurity diffusion region continuous to the p-type impurity injection layer.