JPH0242769A - Manufacture of pin photodiode - Google Patents

Abstract

PURPOSE:To simplify a production process by a method wherein a semiconductor layer is grown epitaxially while an n-type impurity material and a P-type impurity material are being supplied simultaneously onto a photodetecting layer and a desired part is being irradiated with a beam. CONSTITUTION:When a part as a P-type impurity diffusion region 15 is grown epitaxially, a part other than the P-type impurity region 15 is irradiated with a beam 14; the part irradiated with the beam becomes an n-type and the non-irradiated part becomes the P-type 15; when an epitaxial growth operation has been finished, a P-type region is formed in a desired part. Accordingly, when a layer including the last P-type region 15 is grown, e.g., in the case of a pin photodiode, an n-type impurity material and a P-type impurity material are supplied simultaneously, and a part other than a part to be used as a photodetecting part is irradiated with a beam 14; a P-type region 15 is formed in the photodetecting part; as a result, a p-n junction is formed. In addition, when only the n-type impurity material whose optical resolving efficiency is large is supplied and the surface of a substrate 1 is irradiated with a beam, an n<+> type region 3 is formed in a desired part when an epitaxial growth operation has been finished. Thereby, the photodetector can be formed by only one epitaxial growth operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a pin photodiode useful in the fields of optical communication, optical measurement, and optical information processing.

(Prior Art) In recent years, demand for light receiving elements as well as semiconductor lasers has increased in various fields, and research and development are being actively carried out in various places. Until now, various photodetector structures have been proposed, and some of them involve the use of p-oxides such as Zn during the manufacturing process.
There is a diffusion process of type impurities or an ion implantation process, and the quality of the process greatly influences the characteristics of the light receiving element. For example, p due to Zn diffusion in a normal pin photodiode.
These include the formation of an n-junction and the formation of a high electric field region and guard ring structure by ion implantation of an avalanche photodiode with a guard ring.

Conventionally, this pin photodiode is 2 eg Inoa
Taking the As/InP system as an example, it was manufactured using a process as shown in FIG.

(A) n-type InP layer (buffer layer) 2. n-type InGaAs layer (light-receiving layer) 3 on n''-type InP substrate 1
are sequentially grown epitaxially.

(B) A Sin film 4 is deposited on the n-type InGaAs layer 3, and then a window is opened by chemical etching in a portion that will become a light receiving portion using a photolithography process.

(C) Zn is selectively diffused by the quartz sealed tube method using ZnPz as a diffusion source to form a pn junction in the n-type InGaAs layer 3.

(D) Anti-reflection film 6 and A u on Zn diffusion region 5
/Zn to form a p-type electrode 7, and an n-type I
An n-type electrode 8 is formed on the back surface of the nP substrate 1 using Au/Sn.

In this way, the pin structure was formed by Zn diffusion using the quartz sealed tube method using the SiO2 film as a mask, and the Zn diffusion depth was controlled by the diffusion temperature and time.

Further, in this case, an InP-based avalanche photodiode with a guard ring was manufactured by a process as shown in FIG. 5.

(A) n-type InP layer (buffer layer) 2. An n-type InP layer (light-receiving layer) 9 is epitaxially grown in sequence.

(B) S formed by photolithography process
Using the iO layer 4 as a mask, Si ion implantation 10 is performed to form an n9 type InP region (high electric field region) 11.

(C) Similarly to (B), using the 5102 layer 4 as a mask, Zn
6 (D) An anti-reflection film and an A
The n-type electrode 7 is formed using u/Zn, and the n-type InP
An n-type electrode 8 is formed on the back surface of the substrate 1 using Au/Sn.

In this case, although the case where the ion implantation method was used to form the p0 type InP region 13 was explained, the above-mentioned pin
As in the case of photodiodes, Zn is manufactured using the quartz tube method.
The same structure can be obtained using diffusion.

In this way, the n0-type InP region (high electric field region) 11 and the p+-type InP region 13 are formed by a double ion implantation method, and their positions in the n-type layer nP layer 9 are determined by the accelerated ion implantation. The voltage and temperature of the subsequent annealing step were controlled for 9 hours.

(Problems to be Solved by the Invention) However, in the pin photodiode manufactured by the method described above, Zn is selectively diffused using a SiO□ mask, and the diffusion front is connected to the n-type layer n Ga A
Since a pin structure is formed by locating the pin in S, the manufacturing process becomes complicated and there are problems in reproducibility. Further, since diffusion is performed at 400 to 500° C., thermal history has been one of the causes of deterioration of device characteristics.

In addition, in the case of an avalanche photodiode with a guard ring, an n0 type InP layer (high electric field region layer) and a PI type layer P layer are formed using the ion implantation method.
Problems similar to those in the Zn diffusion process for n photodiodes have arisen.

The present invention aims to eliminate the drawbacks of the conventional technique and to form a conventional pin photodiode structure in a single epitaxial growth process.

(Means for Solving the Problems) In order to solve the above-described conventional problems, the present invention provides a semiconductor substrate having a first conductivity type, a buffer layer having the same conductivity type as that on the semiconductor substrate, and a buffer layer having the same conductivity type as that on the semiconductor substrate. A step of sequentially epitaxially growing a light-receiving layer of the same conductivity type as the semiconductor substrate on the semiconductor substrate, and simultaneously supplying n-type and p-type impurity raw materials onto the light-receiving layer and irradiating the semiconductor layer with light to desired portions. and a step of forming a first electrode layer and an antireflection film on the semiconductor layer, and a second electrode layer on the surface of the semiconductor substrate on which the buffer layer, the light-receiving layer, and the semiconductor layer are not formed. This method is used to manufacture pin photodiodes.

Further, the present invention provides, on a semiconductor substrate having a first conductivity type,
A step of sequentially epitaxially growing a buffer layer of the same conductivity type as on the semiconductor substrate, a light-receiving layer of the same conductivity type as the semiconductor substrate on the buffer layer, and simultaneously supplying n-type and p-type impurity raw materials onto the light-receiving layer. and a step of epitaxially growing a high electric field region layer while irradiating a desired portion with light, and simultaneously supplying the n-type and p-type impurity raw materials onto the high electric field region layer, and growing the high electric field region layer around the light irradiation portion. a step of epitaxially growing a semiconductor layer while irradiating the semiconductor layer with light, and forming a first electrode layer, an antireflection film, a buffer layer of the semiconductor substrate, a light receiving layer, a high electric field region layer, and a semiconductor layer on the semiconductor layer. A process of forming a second electrode layer on a non-containing surface is used to manufacture a pin photodiode, particularly an avalanche photodiode.

(for production) The effect of this technical means is as follows.

In epitaxial growth, especially epitaxial growth using organometallic pyrolysis, an n-type impurity raw material whose photolysis efficiency is higher than its thermal decomposition efficiency and a p-type impurity raw material which has almost no light irradiation effect are simultaneously supplied to the substrate surface. When light is irradiated, it is possible to epitaxially grow an n-type layer in the light-irradiated area and a p-type layer in the non-irradiated area. Therefore, the conventional pi
When epitaxially growing a part of an n-photodiode structure where there is a p-type impurity diffusion region, if light is irradiated to a part other than the p-type impurity region, the light-irradiated part becomes n-type and the non-irradiated part becomes p-type, and at the end of epitaxial growth. in,
A p-wall region is formed in a desired portion. Therefore, for example, in the case of a pin photodiode, when growing the final layer including the p-wall region, the above-mentioned n-type and p-type impurity raw materials are simultaneously supplied to irradiate light to the part other than the part that will become the light receiving part. As a result, a p-type region is formed in the light receiving portion, and as a result, a pn junction is formed.

Furthermore, by supplying only the n-type impurity raw material with higher photodecomposition efficiency and irradiating the substrate surface with light, it is possible to epitaxially grow an n9-type layer in the light-irradiated area and an n-type layer in the non-irradiated area. Therefore, in the conventional avalanche photodiode structure, when the part where the n0 type region (so-called high electric field region) is grown in the n type epitaxial layer, the part where the n+ type region will be formed is irradiated with light. The part is n0 type.

The non-irradiated portion becomes n-type, and an n+ type region (high electric field region) is formed in a desired portion at the end of epitaxial growth.

(Example) An example of the present invention will be described based on FIGS. 1 to 3.

FIG. 1 shows the manufacturing process of an InGaAs/InP pin photodiode according to the present invention. in this case.

A pin photodiode structure was epitaxially grown by photoexcited metal organic pyrolysis vapor phase growth. FIG. 2 shows the crystal growth chamber of the epitaxial growth apparatus used. In the same figure, 1 is an InP substrate, 14 is an ArF
Excimer laser light, 16 is In (C, H,), Ga (
C2H,)3. Zn(CH3), supply port 17 is As
H3, PH318i (CH,) 4 (7) supply port, 18 is discharge port, 19 is light entrance window, 20 is carbon susceptor,
21 is a high frequency coil for heating, and 22 is a mask.

As source materials for In, Ga, As, and P, I
n(C2H,), ,Ga(C,H,), ,AsH,,P
H3.

In addition, 5i (CH3
)49 Zn(CH,)2 and H2 were used as carrier gas. Furthermore, ArF excimer laser light was used as the irradiation light source. Each gas at that time is as shown in Table 1,
For example, in the case of an n-type layer nP layer, I n (C, Hs) a is 0
．． 36. PH, 25. 5i(CH3), 0.0
It is mixed at a ratio of 2 (the same applies below).

First, the temperature of the n-type InP substrate 1 placed on a carbon susceptor in a crystal growth chamber is raised to a growth temperature of 600° C. by high-frequency induction heating. At this time, in order to prevent thermal damage to the InP substrate surface, the pH was adjusted to 25cc/
Min was supplied. And after that.

As shown in FIG. 1 (A) and (B), the n-type layer n
A P layer 2 and an n-type InGaAs layer 3 were sequentially grown under the growth conditions shown in Table 1 to create a pin photodiode structure.

Table 1 In this case, the total flow rate is 6.5 Q/win, and the pressure in the crystal growth chamber during growth is 100 Torr. Furthermore, as described above, during the second growth of the n-type nGaAs layer, the n-type impurity raw material Si(CH3)4 and the p-type impurity JX material Zn(CHi)z are simultaneously supplied, and the first As shown in Figure (B), at the same time as the supply starts, ArF excimer laser light 14 in a donut-shaped pattern is applied to 1.
Irradiation was performed perpendicularly to the substrate surface with a power of 5 W/a#.

As a result, the carrier concentration in the non-irradiated area was 5×10”1-3
In the p-type layer nGaAs region 15, an n-type InGaAs region with a carrier concentration of 5×10”an-3 was formed in the irradiated portion, and a pn junction was formed in the InGaAs layer.

And finally, as shown in (C), n-type InGaA
A Sio2 film 4 is formed on the s-layer 3, a p-type electrode M7 is formed using an antireflection film 6 and Au/Zn on the p-type layer nGaAs region 15, and Au/Sn is formed on the back surface of the n-type InP substrate 1. Then, an n-type electrode layer 8 was formed.

According to this example as described above, a pin photodiode structure could be formed by one epitaxial growth. As a result, the process of Zn diffusion can be omitted, greatly simplifying the manufacturing process. Furthermore, since the pn junction position can be controlled by epitaxial growth, the reproducibility of the position has also been improved.

In the case of this example, the n-type layer nP layer 2 and the n-type In
In the case of GaAs layer 3 growth, no light irradiation was performed, but
Even if the entire substrate surface is irradiated with light, the same p as in this example is obtained.
An in-photodiode structure is obtained.

Next, a second embodiment of the present invention, that is, a case of an InP-based avalanche photodiode with a guard ring will be described.

The manufacturing process is shown in FIG. In FIG. 3, the same parts as in FIG. 1 are given the same numbers.

In this case, the growth method used for epitaxial growth of the laser structure, source material, impurity raw material, carrier gas, substrate processing method just before growth, total flow rate, and crystal growth chamber pressure are exactly the same as in the first embodiment. be.

First, an n-type layer nP layer 2 and an n-type InP layer 9 (three layers) were sequentially grown on an n1-type InP substrate 1 under the growth conditions shown in Table 2.

Table 2 can be viewed in the same way as Table 1.

In this case, when growing the second n-type InP layer, the n-type impurity raw material 81 (CH3) 4 is supplied, and at the same time as the supply starts, a circular pattern of ArF excimer laser light is applied as shown in FIG. 14 was irradiated. Also, the third n-type In
During the growth of the P layer, the n-type impurity raw material 5L (CH3) and the n-type impurity raw material Zn (CHl)2 are supplied at the same time, and as shown in FIG. ArF excimer laser light 14 was applied to the pattern (periphery of the irradiation pattern during growth of the second n-type InP layer). Note that the irradiation power of the ArF excimer laser light was 1.5 w/tyl in all cases, and the irradiation was performed from a direction perpendicular to the substrate surface.

As a result, the light irradiated part of the second n-type InP layer is an nI-type InP region 1 with a carrier concentration of I x 10''an-'.
1. The carrier concentration in the non-irradiated area is I x 1016c+n-
This becomes the third n-type InP region, and the third n-type InP region becomes the third n-type InP region.
The light irradiation part of the P layer is an n-type I of I x 10"an-'
nP region, non-irradiated part is p+ of I X 101san-'
A type InP region 13 was formed.

Finally, as shown in (D), a SiO2 film 4 is formed on the n-type InP layer, an anti-reflection film 6 is formed on the p0-type InP region 13, and a p-type electrode layer 7 is formed using Au/Zn. n
An n-type electrode layer 8 was formed using Au/Sn on the back surface of the 1-type InP substrate 1, respectively.

In this embodiment as described above, an avalanche photodiode structure with a guard ring can be formed by one epitaxial growth, and the manufacturing process is greatly simplified. Furthermore, the reproducibility of the position and film thickness of the n'' type InP region (high electric field region) 11 was also greatly improved.

In the embodiments described above, a case has been described in which a photoexcited metal organic pyrolysis vapor phase epitaxy method is used for the structural epitaxial growth of a pin photodiode.
axy) method, optical excitation MOMBE (Metal
OrganicMolecular Beam Epi
(taxy) method, photoexcitation VPE (Vapor Phase)
This can also be achieved using the Epitaxy method. Furthermore, although the case has been described in which ArF excimer laser light is used as the light source for irradiating the substrate, the present invention also provides ArF excimer laser light,
It can also be realized using a Co2 laser, a He-Cd laser, or an excimer laser other than KrF, such as KrF or XeF. Further, the embodiments described above are InGaAs/InP
Although the case of InGaAsP was explained, the present invention is based on InGaAsP.
/InP type.

It can be used not only when using other m-v group compound semiconductors such as A
When using an n-vt group compound semiconductor such as 5Se,
CuGaSe.

It is also applicable when using a chalcopyrite type compound semiconductor such as Cu A (I S ).In this example, 5L (C
H,)4 and Zn(CH3) were used, but the present invention combines an n-type impurity raw material with a higher photolysis efficiency than other thermal decomposition efficiencies and an n-type impurity raw material with almost no light irradiation effect. It is not only applicable when using a combination of an n-type impurity raw material that has almost no light irradiation effect and an n-type impurity raw material that has a higher photolysis efficiency than thermal decomposition efficiency. be. Further, although this embodiment is a case of a pin photodiode, it goes without saying that the present invention can be applied to a phototransistor structure and various other light receiving element structures.

(Effects of the Invention) During the epitaxial growth of the light-receiving element structure, the light-receiving element according to the present invention uses an n(p)-type impurity raw material whose photodecomposition efficiency is higher than its thermal decomposition efficiency, and p (which has almost no light irradiation effect). By supplying n-type impurity raw materials at the same time as n-type impurity raw materials or only supplying n-type impurity raw materials with higher photolysis efficiency and irradiating light onto a desired portion of a desired epitaxial layer, n-type and n-type impurity raw materials can be produced in the same epitaxial layer. A p-wall region or an n-type region and an n+-type region are formed simultaneously.

Therefore, the same structure as the conventional structure after forming Zn diffusion and ion implantation regions can be formed by one epitaxial growth, and the process can be greatly simplified. Further, since the positions of the conventional diffusion and ion implantation regions can be controlled by the position and time of light irradiation, the positional accuracy, especially the positions of the pn junction and the high electric field region, can be improved.

[Brief explanation of the drawing]

FIG. 1 is a process cross-sectional view showing the method for manufacturing a pin photodiode in the first embodiment of the present invention, and FIG. 2 is a photo-excited organometallic pyrolysis vapor phase growth apparatus used in the epitaxial growth process in the embodiment of the present invention. A schematic cross-sectional view of a crystal growth chamber, FIG. 3 is a process cross-sectional view showing a method for manufacturing an avalanche photodiode with a guard ring in the second embodiment of the present invention, and FIG. 4 is a cross-sectional view showing a method for manufacturing a conventional pin photodiode. FIG. 5 is a process cross-sectional view showing a conventional method for manufacturing an avalanche photodiode with a guard ring. 1- n-type InP substrate, 2- n-type layer nP layer, 3-
n-type InGaAs layer, 4...S io, film, 5
...Zn diffusion region, 6...Antireflection film, 7
... p-type electrode layer, 8 ... n-type electrode layer, 9
- n-type InP layer, 10...Si ion implantation,
11... n0 type InP region, 12... Zn ion implantation, 13... P0 type InP region, 14- Ar
F excimer laser light, 15... p-type n Ga
A s area. Figure 1 Patent applicant: Matsushita Electric Industrial Co., Ltd. 2-4.

Claims (10)

[Claims] (1) A step of sequentially epitaxially growing, on a semiconductor substrate having a first conductivity type, a buffer layer having the same conductivity type as that on the semiconductor substrate, and a light-receiving layer having the same conductivity type as the semiconductor substrate on the buffer layer; On the light-receiving layer, n-type and p-type
A step of epitaxially growing a semiconductor layer while simultaneously supplying a type impurity raw material and irradiating a desired portion with light, a first electrode layer and an antireflection film on the semiconductor layer, a buffer layer of the semiconductor substrate, and a light-receiving layer. A method for manufacturing a pin photodiode, comprising the steps of: forming a second electrode layer on a surface on which a semiconductor layer is not formed. (2) A claim in which the epitaxial growth method is metal-organic pyrolysis vapor phase epitaxy, halide vapor phase epitaxy, hydride vapor phase epitaxy, gas source molecular beam epitaxy, or molecular beam epitaxy (
1) Method for manufacturing the pin photodiode described above. (3) Claim (1) wherein the light source used for light irradiation is an excimer laser, an Ar laser, a Co_2 laser, or an ultraviolet lamp.
A method of manufacturing the described pin photodiode. (4) Claim (1) wherein at least one of the n-type and p-type impurity raw materials supplied at the same time has a photodecomposition efficiency higher than a thermal decomposition efficiency at the epitaxial growth temperature.
) A method for manufacturing a pin photodiode as described above. (5) The n-type and p-type impurity raw materials are Si(C
Claim (4) which is H_3)_4, Zn(CH_3)_2
) A method for manufacturing a pin photodiode as described above. (6) epitaxially growing a buffer layer of the same conductivity type as the semiconductor substrate on a semiconductor substrate having a first conductivity type, and a light-receiving layer of the same conductivity type as the semiconductor substrate on the buffer layer; On the light-receiving layer, n-type and p-type
A step of epitaxially growing a high electric field region layer while simultaneously supplying a type impurity raw material and irradiating a desired portion with light, simultaneously supplying the n-type and p-type impurity raw materials on the high electric field region layer, and a step of epitaxially growing a semiconductor layer while irradiating a peripheral area of the light irradiation part with light, a first electrode layer and an antireflection film on the semiconductor layer, a buffer layer of the semiconductor substrate, a light receiving layer, a high electric field region layer,
A method for manufacturing a pin photodiode, comprising the step of forming a second electrode layer on a surface where a semiconductor layer is not formed. (7) A claim in which the epitaxial growth method is a metal-organic pyrolytic vapor phase epitaxy method, a halide vapor phase epitaxy method, a hydride vapor phase epitaxy method, a gas source molecular beam epitaxy method, or a molecular beam epitaxy method (
6) Method for manufacturing the pin photodiode described above. (8) Claim (6) wherein the light source used for light irradiation is an excimer laser, an Ar laser, a Co_2 laser, or an ultraviolet lamp.
A method of manufacturing the described pin photodiode. (9) At least one of the n-type and p-type impurity raw materials supplied at the same time has a photodecomposition efficiency higher than a thermal decomposition efficiency at the epitaxial growth temperature (6).
) A method for manufacturing a pin photodiode as described above. (10) The n-type and p-type impurity raw materials are Si(
Claim (CH_3)_4, Zn(CH_3)_2
9) Method for manufacturing the pin photodiode described above.