JPH02183518A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve semiconductor characteristics by making a carrier concentration profile to be sharp in the interface of a p-type GaAs film by setting the temperature of a substrate to a value which is lower than that where the carrier concentration of the GaAs film which grow by a molar beam of triethylgallium(TEG) and that of metal arsenic As4. CONSTITUTION:After setting the temperature of a substrate to 550 deg.C where the carrier concentration becomes the minimum, adding irradiation of TEL molecular rays and Si molar rays to that of As4 molecular rays, and then allowing an n<+>-GaAs collector contact layer 2 doped with Si, the strength of Si molecular rays is reduced to allow an n-GaAs collector layer 3 which is doped with Si to grow. Then, the temperature of the substrate is set to 430 deg.C while irradiating only As4 molar rays and irradiation of TEG molar rays is added to that of As4 molecular rays for allowing a p<+>-GaAs base layer 4 doped with C to grow, thus stopping irradiation of the TEG molar rays. Then, the temperature of the substrate is set to 550 deg.C while irradiating only the As4 molar rays and irradiation of the TEG molecular rays, Al molecular rays, and Si molecular rays is added to that of the As4 molecular rays, thus forming an emitter layer 5A.

Description

[Detailed Description of the Invention] [Summary] A method for manufacturing a semiconductor device, in particular, a method for producing a p-type GaAs film or a p-type G film on a semiconductor substrate using a molecular beam epitaxy device.
Regarding the method of growing a multilayer semiconductor film having an aAs film and an n-type or high-purity GaAs film, in order to steepen the carrier concentration profile at the interface of the p-type GaAs film, the p-type impurity of the GaAs film is replaced with Be. The purpose of this study is to reduce the carrier concentration of the GaAs film grown by triethyl gallium molecular beams and metallic arsenic molecular beams. The substrate temperature is set to a second temperature lower than the first temperature which is approximately the lowest, and the p-type GaAs film is grown by the two molecular beams, and the step of growing the p-type GaAs film. , a step of setting the substrate temperature at the first temperature and growing a high-purity GaAs film using the two molecular beams, or adding a molecular beam of an n-type impurity at that time to grow an n-type GaAs film; The above-mentioned high-purity GaAs
When growing the film or the n-type GaAs film, the substrate temperature is made the same as the temperature during the growth of the p-type GaAs film, and cracked arsine molecular beams are used instead of the metallic arsenic molecular beams.

[Industrial application field]

The present invention relates to a method for manufacturing a semiconductor device, and in particular to a method for manufacturing a semiconductor device, in particular, p-type GaAs is grown on a semiconductor substrate using a molecular beam epitaxy device.
film or p-type GaAs film and n-type or high purity GaA3
The present invention relates to a method for growing a multilayer semiconductor film having a multilayer structure.

Semiconductor devices using a multilayer semiconductor film consisting of a p-type GaAs film and an n-type or high-purity GaAs film include hetero bipolar transistors (HBTs) and pin diodes, which have better characteristics than those using silicon. be.

In these semiconductor devices, the steepness of the carrier concentration profile at the interface within the semiconductor film is important. The acidity depends on the growth method of the semiconductor film and the type of impurity that makes the semiconductor P-type or N-type.

[Conventional technology]

FIG. 3 shows an example of a semiconductor device using a multilayer semiconductor film including a p-type GaAs film and an n-type GaAs film
FIG. 2 is a side sectional view showing an outline of BT.

In the figure, 1 is a semi-insulating GaAs substrate, 2 is n'
GaAs collector contact layer, 3 is n-GaAs
Collector layer, 4 is p”-GaAs base layer, 5 is n-A
] GaAs emitter layer, 6 an n-GaAs emitter contact layer, 7 a collector electrode, 8 a base electrode, and 9 an emitter electrode. Although the structure of the emitter layer 5 may be slightly different as in the embodiments described later, it is shown here for the sake of simplicity.

This transistor is manufactured by sequentially growing a collector contact layer 2 to an emitter contact layer 6 on a substrate 1, performing necessary etching, and forming electrodes 7 to 9. Since a steep carrier concentration profile at the interface with layer 5 is required, the above growth is often performed by molecular beam epitaxy (MBE), which has excellent controllability of film thickness and interface.

And the traditional method in its growth is Ga.

As4, AI% The molecular beams of Be as a p-type impurity and St as an n-type impurity are combined, and the substrate temperature is set to 6
Generally, the temperature is 00 to 700°C.

[Problems to be Solved by the Invention] However, due to the large thermal diffusion coefficient of BeO, which serves as a p-type impurity, and the considerably high substrate temperature during growth, the desired carrier concentration at the interface of the P'' GaAs base layer 5 is There is a problem that the steepness of the concentration profile is not sufficiently satisfied, and the characteristics of the transistor are deteriorated.

This means that P-type GaAs film and n-type or high-purity GaAs film
This is common in many semiconductor devices using a multilayered semiconductor film having an S film.

On the other hand, as a p-type impurity for GaAs, carbon has a smaller thermal diffusion coefficient than Be.

Therefore, the present invention provides a method for manufacturing a semiconductor device, in particular, a method for manufacturing a semiconductor device using a molecular beam epitaxy apparatus to form p-type GaAs on a semiconductor substrate.
film or p-type GaAs film and n-type or high purity GaAs
In a method for growing a multilayer semiconductor film having a multilayer structure, the p-type impurity of the GaAs film is changed to C, which has a smaller thermal diffusion coefficient than Be, in order to steepen the carrier concentration profile at the interface of the p-type GaAs film. The object of the present invention is to make it possible to lower the substrate temperature during growth.

[Means to solve the problem]

For the above purpose, triethyl gallium Ga(Cz Hs)s
The substrate temperature is set to a second temperature lower than the first temperature at which the carrier concentration of the GaAs film grown by the molecular beam of TEG> and the molecular beam of metallic arsenic As4 is almost the lowest, and the two molecular beams The problem is solved by the growth method of the present invention, which grows a GaAs film, and also includes the step of growing the P-type GaAs film, setting the substrate temperature to the 1/IA degree, and using the two molecular beams to increase the temperature. The problem is solved by the growth method of the present invention, which comprises a step of growing a high-purity GaAs film or adding a molecular beam of n-type impurity at that time to grow an n-type GaAs film. When growing a GaAs film or an n-type GaAs film, the substrate temperature is made the same as the temperature during the growth of the p-type GaAs film, and a molecular beam of cracked (pyrolyzed) arsine AsH3 is used instead of the molecular beam of As. This problem is solved by the growth method of the present invention.

[Function] FIG. 1 is a carrier concentration characteristic diagram illustrating the present invention, in which the vertical axis represents the P-type carrier concentration and the horizontal axis represents the substrate temperature during growth. The solid line ■ connecting . is a GaAs film grown using a TEG molecular beam and an As molecular beam, and the broken line ■ connecting ○ is a GaAs film grown using a TEG molecular beam and an arsine molecular beam cracked at 920°C. The broken line (■) connecting Δ indicates the case where the cracking temperature is set to 850°C. In these growths, no molecular beam of P-type impurity is added, but carbon (C) in TEG is introduced and the carriers in the GaAs film become P-type. That is, the C introduced here is a p-type impurity having a smaller thermal diffusion coefficient than Be used in the conventional method.

The characteristics of the broken lines ■ and ■ are shown in the document App1. Phys.

Lett, 51.1987 p., 1109, the p-type carrier concentration decreases as the substrate temperature is lowered, and the GaAs film is substantially free of impurities at substrate temperatures below about 500 to 600°C. It has high purity and does not contain.

On the other hand, the characteristics indicated by the solid line (■) were discovered by the present inventor. The characteristic is that the carrier concentration is the lowest at a substrate temperature of around 550'C, and the carrier concentration gradually increases at temperatures around that temperature. That is, when compared with the characteristics indicated by the broken lines (■) and (2), the characteristics are similar on the high substrate temperature side, but the trends are reversed on the low substrate temperature side. By adjusting the substrate temperature to an appropriate temperature between 550°C and 400°C, we created a high-purity GaAs film with a carrier concentration of 2X1016/c++t and a highly doped p-type GaAs film with a carrier concentration of 3X10''/c. This shows that it is possible to grow a GaAs film with any P-type carrier concentration between the films.

In addition, the property of the solid line ■ is As, the pressure of the molecular beam is 2XIO
-'Pa, but by increasing this pressure, the lowest carrier concentration can be further lowered. For example, if the pressure is set to 2Xl0-2Pa, the carrier concentration becomes 1.5X10''/c+fl. I know it will happen.

On the other hand, it is well known that by doping a high-purity GaAs film with n-type impurities, the formed GaAs film can be made n-type even if the impurities contained in the high-purity GaAs film are p-type.

The present invention takes advantage of the above.

Therefore, according to this explanation, in the growth method of the present invention, GaA
The p-type impurity of the S film is C, which has a smaller thermal diffusion coefficient than Be, and the substrate temperature during growth is 600-700℃ compared to the conventional method.
It will be easily understood that the temperature will be lower than 0'C. This makes the carrier concentration profile at the interface of the P-type GaAs film steeper than in the conventional method.

In addition, in the growth method of the present invention, when using TEG molecular beams and As molecular beams to grow a high-purity GaAs film or an n-type GaAs film, it is only necessary to change the substrate temperature when growing a p-type GaAs film. In addition, when using a common molecular beam, and when using a TEG molecular beam and an arsine molecular beam to grow a high-purity GaAs film or an n-type GaAs film,
A feature of this method is that the substrate temperature is kept the same during the growth of a p-type GaAs film by simply switching the molecular beam.

It goes without saying that in the latter case, the substrate temperature may be switched.

[Example] Hereinafter, an example of manufacturing a semiconductor device using the growth method according to the present invention will be described using the side cross-sectional view of FIG. 2, taking an HBT as an example.

In the HBT shown in FIG. 2, the emitter layer 5 in the HBT shown in FIG. 3 is replaced with a graded n-AlGaAs layer 5c.

n-AlGaAs layer 5b and graded n-AlG
The emitter layer 5A has a three-layer structure consisting of an aAs layer 5c.

The manufacturing procedure of this transistor is similar to that of the HBT shown in FIG. 3, but the growth method of the present invention is applied when growing from the collector contact layer 2 to the emitter contact layer 6 on the substrate 1.

An example of this growth is as follows. This is high purity G
This applies when using TEG molecular beams and As molecular beams to grow an aAs film or an n-type GaAs film.

That is, the substrate 1 is placed in an MBE apparatus, and first, the natural oxide film on the surface of the substrate 1 is removed by heating the substrate 1 to 600° C. or higher under irradiation with As and molecular beams.

Next, the substrate temperature was set at 550°C, and 780 molecular beam and Si molecular beam irradiation were added to the A54 molecular beam irradiation.
n”-Ga doped with Si to 3X1018/cnl
After growing the As collector contact N2 to a thickness of 550 nm, the intensity of the Si molecular beam was lowered and the Si was grown to 3X1016/
cn! The n-GaAs collector layer 3 doped with
Grows to 50 nm. Growth is stopped by stopping irradiation with the 780 molecular beam and the Si molecular beam.

Next, while irradiating only As and molecular beams, the substrate temperature was increased to 4.
Set at 30°C, add 780 molecular beam irradiation to As and molecular beam irradiation, and C is 1.5 x 10”/cnl.
A p”-GaAs base layer 4 doped with a thickness of 1
After growing to 100n, irradiation with the 780 molecular beam is stopped.

Next, while irradiating only As and molecular beams, the substrate temperature was increased to 5.
Set the temperature to 50°C, add 780 molecular beam, A1 molecular beam, and Si molecular beam irradiation to As and molecular beam irradiation to
Graded nAlGa doped with X1017/c
As layer 5a (thickness 50 nm), n-AIGaA
s layer sb (thickness 150 nm) and graded n −
An emitter layer 5A is formed by sequentially growing an AlGaAs layer 5c (thickness 30r++n).

Next, when the thickness of the graded n-AlGaAs layer 5c reached 30 nm, the irradiation of the A1 molecular beam was stopped and the intensity of the Si molecular beam was increased to form a 5×1 layer of Si.
An n-GaAs emitter contact layer 6 doped with 0''/Ca is grown to a thickness of 1100 nm to complete the growth series.

It was confirmed that the maximum current gain of the transistor grown and manufactured in this way was improved from 30 to 40 compared to the transistor of the same configuration manufactured using the conventional growth method described above. .

Next, another example of the above growth will be described.

When using TEG molecular beams and arsine molecular beams to grow high-purity GaAs films or n-type GaAs films, 3
Inferred.

That is, the substrate 1 is placed in an MBE apparatus, and first, the substrate 1 is rotated at 920°.
Substrate l under irradiation of arsine molecular beam cracked with C
The natural oxide film on the surface of the substrate 1 is removed by heating to 600° C. or higher.

Next, the substrate temperature was set at 430°C, and 780 molecular beam and Si molecular beam irradiation were added to the arsine molecular beam irradiation described above to form a 3×10”/CT11 Si-doped n”
- After growing the GaAs collector contact layer 2 to a thickness of 550 nm, the intensity of the consonant beam is lowered by the amount of Si, and the Si layer is grown to a thickness of 3×1.
An n-GaAs collector layer 3 doped to 0''/cn! is grown to a thickness of 550 nm.

Next, when the thickness of the collector layer 3 reached 550 nm, the irradiation with the Si molecular beam was stopped, and the irradiation with the arsine molecular beam was switched to the irradiation with the As4 molecular beam.
Molecular beam and 780 molecular beam irradiation, substrate temperature 430
Keep it at °C until C is 1.5×10”/c+fl
A p”-GaAs base layer 4 doped with a thickness of 11
Grows to 00n.

Next, when the thickness of the base layer 4 reached 1100 nm, the irradiation with As and molecular beams was switched to the irradiation with arsine molecular beams, and the irradiation with A1 molecular beams and Si molecular beams was replaced with the irradiation with arsine molecular beams and 780 molecular beams. Apply irradiation and maintain the substrate temperature at 430″C to reduce the Si to 5×10′7
/c1i1 doped graded nAlGaAs layer 5a (thickness 50 nm), n-AlGaAs layer 5b
(thickness 150nm) and graded n AlGa
An emitter layer 5A is formed by sequentially growing As layers 5c (Jt: 30 nm).

Next, when the thickness of the graded n-AlGaAs layer 5c reached 30 nm, the irradiation of the At molecular beam was stopped, and the intensity of the Si molecular beam was increased to increase the St.
An n-GaAs emitter contact layer 6 doped with ``/cTA'' is grown to a thickness of 10m to complete the growth series.

Note that the cracking temperature of arsine in these growths is not limited to 920°C.

The characteristics of transistors grown and manufactured in this way are:
It is desired that the transistor be substantially the same as the transistor according to the previous embodiment, and is a significant improvement over a transistor of the same configuration manufactured by conventional growth methods.

In the embodiment described above, an n-type GaAs film is added to a P-type GaAs film.
This is the case when combining an S film, but also when manufacturing a pin diode by combining a high purity GaAs film instead of an n-type GaAs film, the carrier concentration profile at the interface of the p-type GaAs film should be made steep. The fact that the present invention is extremely effective against
It will be easily understood from the explanation using the figures.

〔Effect of the invention〕

As explained above, according to the structure of the present invention, there is provided a method for manufacturing a semiconductor device, in particular, a p-type GaAs film, or a p-type GaAs film and an n-type or high-purity GaAs film on a semiconductor substrate using a molecular beam epitaxy apparatus. In a method for growing a semiconductor film with a multilayer structure having By p
This has the effect of making the carrier concentration profile at the interface of the GaAs film steeper, thereby making it possible to improve the characteristics of the semiconductor device.

[Brief explanation of the drawing]

FIG. 1 is a carrier concentration characteristic diagram for explaining the present invention, FIG. 2 is a side sectional view of an HBTO for explaining an embodiment, and FIG. 3 is a side sectional view showing an outline of the HBT. In the figure, l is a semi-insulating GaAs substrate, 2 is an n'-GaAs collector contact layer, and 3 is an n-G
4 is a p'-GaAs base layer, 5 is an n-AlGaAs emic layer, 58 is an emitter layer, 5a is a graded n-AIGaAs layer, 5b is an n-AlGaAs layer,
-AIGaAs layer, 5c is graded n-AIGaAs layer 5c. 6 is an n GaAs emitter contact layer. 1000/75 (K-Tsusei refusal Ts C'C), fee month ゛ε, saying 兇e月MARoshihei 11 A brutal cow persecution, melon] No. 1 2

Claims (3)

[Claims] (1) Using a molecular beam epitaxy device, the substrate temperature is set to a second temperature lower than the first temperature at which the carrier concentration of the GaAs film grown by triethyl gallium molecular beams and metallic arsenic molecular beams is approximately the lowest. . A method for manufacturing a semiconductor device, characterized in that a p-type GaAs film is grown using the above two molecular beams. (2) Using a molecular beam epitaxy device, set the substrate temperature at a second temperature lower than the first temperature at which the carrier concentration of the GaAs film grown by triethyl gallium molecular beams and metallic arsenic molecular beams is approximately the lowest. , a step of growing a p-type GaAs film using the two molecular beams, and setting the substrate temperature to the first temperature and growing a high-purity GaAs film using the two molecular beams, or
A method for manufacturing a semiconductor device, comprising the step of growing an n-type GaAs film by adding a molecular beam of a type impurity. (3) In the manufacturing method according to claim 2, when growing the high-purity GaAs film or the n-type GaAs film, the substrate temperature is made the same as the temperature during the growth of the p-type GaAs film, and the molecules of the metal arsenic are A method for manufacturing a semiconductor device, characterized in that a molecular beam of cracked arsine is used instead of a wire.