JP2003115455A - Method of manufacturing iii-v compound semiconductor crystal containing antimony - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a III-V compound semiconductor crystal containing antimony for upgrading the quality of a compound semiconductor crystal containing antimony grown by using a metal-organic vapor- phase growth method. SOLUTION: This method is to manufacture a III-V compound semiconductor crystal containing antimony, which contains at least two kinds or more of group-V components, one of which is antimony, by alternately and periodically repeating a first process of simultaneously supplying a source gas for a group-III component and a source gas for antimony, and a second process of simultaneously supplying the source gas for the group-III component and source gases for group-V components other than antimony.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an antimony-containing III-V group compound semiconductor crystal for producing an antimony compound semiconductor by using a metal organic chemical vapor deposition method.

[0002]

2. Description of the Related Art Antimony-based compound semiconductors contain antimony as a group V raw material, and these compound semiconductors have various uses. For example, compound semiconductors containing antimony are used in high electron mobility transistors (High Electron Mobility Transistors) to improve the characteristics of ultra-high speed devices.
cistor: HEMT) or heterojunction bipolar transistor (HBT) band structure profile, in order to introduce a type-2 structure in addition to the type-1 structure that is generally used for the heterostructure of compound semiconductors. Is used for. This type-1 structure is shown in Fig. 6.
It is shown in (a) and the type-2 structure is shown in FIG. 6 (b). FIG. 6C shows a type-3 structure. Further, compound semiconductors containing antimony are expected to be applied to semiconductor laser reflecting mirrors utilizing the difference in refractive index from other materials, light emitting / receiving elements in the long wavelength region, and the like.

For example, when HBT is formed on InP, GaAsSb is combined, when HEMT is formed, AlAsSb is combined, and InAsSb or the like is combined with other compound semiconductor in the light emitting element. It is being appreciated.

In manufacturing these elements, the crystal quality of the compound semiconductor containing antimony has a great influence on the performance and reliability of the element, and high crystal quality is required.

As a crystal growth method for compound semiconductors, there is metal organic chemical vapor deposition (MOCVD) which is suitable for mass production. When a compound semiconductor containing antimony is grown by using this metalorganic vapor phase epitaxy method, conventionally, all the raw material gases necessary for producing a mixed crystal are simultaneously supplied to the reaction tube. This state is shown in FIG. According to FIG. 7, an antimony-containing compound semiconductor is manufactured by a gas supply flow of a general metal organic chemical vapor deposition method. This antimony-containing compound semiconductor contains two or more kinds of Group V elements. When two or more group V elements are included, their composition is generally controlled by the flow rate ratio of the source gas.

[0006]

However, the conventional crystal growth method has the following problems. That is, with this crystal growth method, it was difficult to produce a compound semiconductor containing antimony and to improve the quality thereof for the following reasons (1) to (3).

(1) III such as gallium and aluminum
The binding force between group elements and antimony is V for arsenic and phosphorus.
Weaker than the bond strength with group elements. Therefore, if each source gas is supplied simultaneously (Fig. 7), for example, Al-A
s and Ga-As are preferentially formed. Therefore, unless the flow rate ratio between the group V raw material and the group III raw material (hereinafter referred to as V / III ratio), which normally takes a value of several tens to several hundreds, is set to a low value of around 1, antimony is taken into the crystal. Absent. However, when the V / III ratio is lowered, particularly in the case of a crystal containing aluminum, high concentration of oxygen and carbon are mixed and the crystal quality is deteriorated.

On the other hand, when the V / III ratio is increased, the incorporation of antimony is hindered by other V group elements and the growth surface is apt to be roughened. Further, even a slight fluctuation of V / III ratio of about 0.1 sensitively affects such crystal quality and surface morphology.

(2) When manufacturing a device using a compound semiconductor, it is important to realize the designed band structure accurately in order to obtain the intended device characteristics. The same applies to compound semiconductors containing antimony. For that purpose, it is necessary to precisely control the antimony composition. However, it is difficult to control the composition due to the competitive reaction with other materials described above.

(3) Vapor pressure of antimony (600 [° C]
And Sb: 6 × 10 ^-2 [torr]) is the vapor pressure of other V group (600
At [℃], P ₄ : 2 × 10 ⁴ [torr], As ₄ : 4 × 10 ² [tor
r)) more than 4 digits lower. Therefore, when grown at a low temperature, excess antimony is likely to be condensed. Also,
Melting point of antimony compounds (InSb: 525 [℃], GaSb: 7
12 [℃]) is the melting point of other compounds (GaAs: 1240 [℃],
Generally lower than AlAs: 1740 [° C]). If the growth temperature is raised in order to prevent the mixing of impurities and the condensation of antimony, the low melting point of the antimony compound causes the surface / interface to become rough.

For the above reasons, for example, when trying to grow lattice-matched AlAs _0.56 Sb _0.44 on an InP substrate,
When the arsenic raw material is supplied at a flow rate ratio suitable for AlAs growth, even if the antimony raw material is supplied up to the precipitation limit of antimony simple substance, arsenic is much more easily bonded to aluminum than antimony. Therefore, only crystals with a composition ratio very close to that of AlAs can be obtained. Further, if the supply amount of the arsenic raw material is reduced in order to suppress the competition between arsenic and antimony, the concentration of impurities such as oxygen and carbon will increase and the crystal quality will deteriorate.

As described above, when a compound semiconductor containing two or more kinds of group V, one of which is antimony, is formed by the metal organic chemical vapor deposition method, the competitive reaction between antimony and the other group V elements causes It was extremely difficult to improve the quality of crystals.

The present invention solves the above problems and improves the quality of a compound semiconductor crystal containing antimony grown by metalorganic vapor phase epitaxy.
It is an object of the present invention to provide a method for producing a Group V compound semiconductor crystal.

[0014]

In order to solve the above-mentioned problems, the invention according to claim 1 contains at least two kinds of group V raw materials, one of which is antimony, and an antimony-containing III-V group compound semiconductor crystal. In the manufacturing method of
Alternately, a first step of simultaneously supplying a group II source gas and an antimony source gas and a second step of simultaneously supplying the group III source gas and a source gas of a group V element other than antimony and A method for producing an antimony-containing III-V group compound semiconductor crystal, which is characterized by repeating periodically.

In the present invention, while supplying the group III raw material,
Crystal growth is performed by alternately supplying the antimony raw material of the V group raw material and the other V group raw material. This gives V
It is possible to avoid the competition between the group elements and to select the growth conditions suitable for each layer, and to improve the quality of the crystal. Further, since the first step and the second step are alternately and periodically repeated, the composition of the crystal can be determined by the ratio of the supply times of the respective group V raw materials. Therefore, precise composition control is possible.

According to a second aspect of the invention, in the method for producing an antimony-containing III-V compound semiconductor crystal according to the first aspect, the first step and the second step are performed by a metal organic chemical vapor deposition method. It is characterized by The invention of claim 3 is the antimony-containing III-V according to claim 1 or 2.
The method for producing a group compound semiconductor crystal is characterized by including a third step of supplying only the group III source gas between the first step and the second step. The invention of claim 4 is the antimony-containing III-V according to claim 3.
In the method for producing a group compound semiconductor crystal, the third step is performed by a metal organic chemical vapor deposition method.

BEST MODE FOR CARRYING OUT THE INVENTION Next, the first embodiment of the present invention,
2 will be described in detail with reference to the drawings.

[First Embodiment] FIG. 1 shows a method of manufacturing an antimony-containing III-V group compound semiconductor crystal according to this embodiment. In this embodiment, a raw material gas of antimony, which is a Sb-based group V source material, and another group V source material gas are alternately supplied to grow a crystal by a metal organic chemical vapor deposition method.

That is, in this embodiment, at the same time when the supply of the group III source gas is started, another group V source gas is supplied during the supply time t11 (first step). Subsequently, the raw material gas of antimony is supplied during the supply time t21 (second step). Thereafter, in the same manner, the other group V source gas is supplied during the supply time t12, the antimony source material gas is supplied during the supply time t22, and the other group V source gas is supplied during the supply time t13. And the raw material gas of antimony is supplied during the supply time t23.

The supply time of each gas is set such that the antimony-containing layer and the antimony-free layer each have a film thickness (critical film thickness) or less that can include lattice mismatch with the substrate.
Further, the film thickness ratio is made equal to the required composition ratio of the mixed crystal.

In alternate supply, the antimony-containing layer and the antimony-free layer are set to the optimum V / III ratio of each group V raw material in order to improve the crystal quality. Further, the supply times t11 to t13 and the supply time t21
The composition of the crystal is controlled by ~ t23. That is,
According to this embodiment, since the gas flow can be set so that the V / III ratio is optimum for the antimony-containing layer and the antimony-free layer, high quality crystals can be produced.

[Second Embodiment] FIG. 2 shows a method of manufacturing an antimony-containing III-V group compound semiconductor crystal according to this embodiment. In this embodiment, a raw material gas of antimony, which is a Sb-based group V source material, and another group V source material gas are alternately supplied to grow a crystal by a metal organic chemical vapor deposition method. At this time, a purging time in which only the group III source gas is supplied and the group V source gas is not supplied is inserted between the flows in which the group V source materials are supplied.

That is, in this embodiment, at the same time when the supply of the group III source gas is started, another group V source gas is supplied during the supply time t11 (first step). Subsequently, during the purging time t31, the supply of the raw material gas of antimony and other group V source gas is stopped, and III
Only the group source gas is supplied (third step). Subsequently, the raw material gas of antimony is supplied during the supply time t21 (second step). Subsequently, during the purging time t32, the supply of the raw material gas of antimony and the other group V source gas is stopped, and only the group III source gas is supplied (third step). After this, in the same manner, the supply time t12
During the purging time t33, only the group III source gas is supplied during the purging time t33.
During 22, the raw material gas of antimony is supplied.

According to this embodiment, the influence of the group V source gas previously flowed, which remains in the reaction tube, can be removed by the purging times t31 to t33.
Moreover, the growth surface to which the next group V source gas is supplied is III
Since it is covered with the group atoms, the substitution of the group V atoms can be suppressed and the interface characteristics can be improved.

[0024]

EXAMPLES Next, Examples 1 to 3 will be described.

[Embodiment 1] This embodiment is shown in FIG. This example shows AlAs _0.56 Sb _0.44 lattice-matched on an InP substrate.
It shows an example of growing. For the growth of AlAs _0.56 Sb _0.44 , TMAl (partial pressure: 5.5 × 10 ^-4 [tor
r]), AsH ₃ (partial pressure: 4.75 × 10 ^-3 [tor
r]), TMSb as an antimony raw material (partial pressure: 5.5 × 10
^-4 [torr]) is used. The V / III ratio is AsH ₃ / TMAl =
8.2, TMSb / TMAl = 1.0. Supply times t11 to t13 and t21 to t23 (FIG. 1) of AsH ₃ and TMSb are 2 [sec] and 4.7 [sec], respectively.

First, a base for growing AlAs _0.56 Sb _0.44 is formed. First, the InP substrate 31 to be grown is transferred into a growth chamber (not shown). Next, the temperature is raised while supplying hydrogen as a carrier gas to the growth chamber, PH ₃ is supplied when the temperature reaches 300 [° C], and further the temperature is raised to 640 [° C] to perform thermal cleaning. . After the cleaning is completed, the temperature is lowered to the growth temperature of 600 [° C.] and TMIn is supplied to form the InP buffer layer 32.

When the formation of the InP buffer layer 32 is completed, the supply of TMIn and PH ₃ is stopped, and AlAs _0.56 Sb _0.44 is continuously grown as it is. First, TMAl and AsH ₃
Supply simultaneously for seconds. Thereby, the AlAs layer 33 is grown. Next, the supply of AsH ₃ is stopped while TMAl is supplied, and TMSb is supplied for 4.7 seconds at the same time. Thereby, the AlSb layer 34 is grown. The above is one cycle,
Repeat until n cycles to reach the required film thickness.

[Embodiment 2] This embodiment is shown in FIG. This example shows AlAs _0.56 Sb _0.44 lattice-matched on an InP substrate.
This is an example in which a purging time is inserted at the time of switching the group V raw material when growing the. To grow AlAs _0.56 Sb _0.44 , TMAl (partial pressure: 5.5 × 10 ^-4 [to
rr]), AsH ₃ (partial pressure: 4.75 × 10 ^-3 [tor
r]), TMSb as an antimony raw material (partial pressure: 5.5 × 10
^-4 [torr]) is used. The V / III ratio is AsH ₃ / TMAl =
8.2, TMSb / TMAl = 1.0. AsH ₃ supply time and TMSb supply time t11 to t13, t21 to t23 (FIG. 2) are 2 [sec] and 4.7 [sec], respectively, and AsH ₃ to TM
Purging times t31 and t33 when switching to Sb
(FIG. 2) and the purging time t32 (FIG. 2) when switching from TMSb to AsH ₃ are both 1.0 [sec].

First, an underlayer for growing AlAs _0.56 Sb _0.44 is formed. First, the InP substrate 41 to be grown is transferred into the growth chamber. Next, the temperature is raised while supplying hydrogen as a carrier gas to the growth chamber, PH ₃ is supplied when the temperature reaches 300 [° C.], and the temperature is further raised to 640 [° C.] to perform thermal cleaning. After cleaning, the growth temperature is 600
The temperature is lowered to [° C] and TMIn is supplied to supply the InP buffer layer 4
Form 2.

When the formation of the buffer layer 42 is completed, the supply of TMIn and PH ₃ is stopped, and AlAs is continuously supplied.
_It grows _0.56 Sb _0.44 . First, TMAl and AsH ₃ are simultaneously supplied for 2 seconds. Thereby, the AlAs layer 43 is grown. Next, the supply of AsH ₃ is stopped while TMAl is supplied, and the purge is performed for 1 second. At this time, the growth surface of the AlAs layer 43 is covered with the Al atom layer 45 of group III atoms. Next, TMSb is supplied while TMAl is being supplied, and is simultaneously supplied for 4.7 seconds. Thereby, the AlSb layer 44 is grown. Next, the supply of TMSb is stopped while TMAl is being supplied, and the purge is performed for 1 second. At this time, the growth surface of the AlSb layer 44 is covered with the Al atomic layer 45. The above is set as one cycle, and the required film thickness is reached n
Repeat until cycle.

[Embodiment 3] This embodiment is shown in FIG. In this example, GaAs _0.51 Sb _0.49 lattice-matched on an InP substrate is used.
It shows an example of growing. For the growth of GaAs _0.51 Sb _0.49 , TEGa (partial pressure: 5.5 × 10 ^-4 [tor
r]), AsH ₃ (partial pressure: 4.75 × 10 ^-3 [tor
r]), TMSb as an antimony raw material (partial pressure: 5.5 × 10
^-4 [torr]) is used. The V / III ratio is AsH ₃ / TEGa =
8.2, TMSb / TEGa = 1.0. AsH ₃ supply time t11 ~
t13 (FIG. 1) and TMSb supply times t21 to t23 (FIG. 1) are 2.9 [sec] and 4.3 [sec], respectively.

First, a base for growing GaAs _0.51 Sb _0.49 is formed. First, the InP substrate 51 to be grown is transferred into the growth chamber. Next, the temperature was raised while supplying hydrogen as a carrier gas to the growth chamber, and when the temperature reached 300 [° C], PH ₃
Is further supplied, and the temperature is further raised to 640 [° C.] to perform thermal cleaning. After the cleaning is completed, the temperature is lowered to 600 [° C.] and TMIn is supplied to form the InP buffer layer 52. After the formation, the temperature is lowered to the growth temperature of 550 [° C].

When the growth temperature is reached, GaAs _0.51 Sb _0.49 is continuously grown as it is. First, TEGa and AsH ₃
Supply at the same time for 2.9 seconds. Thereby, the GaAs layer 53 is formed. Next, the supply of AsH ₃ is stopped while the TEGa is being supplied, and TMSb is supplied for 4.3 seconds at the same time. Thereby, the GaSb layer 54 is formed. The above is set as one cycle, and is repeated until n cycles to reach the required film thickness.

Although the first and second embodiments and the first to third embodiments of the present invention have been described above in detail, the specific configuration is not limited to these, and is within a range not departing from the gist of the present invention. Even if the design is changed, it is included in the present invention.

[0035]

As described above, according to the present invention, III
While supplying group materials, antimony materials and other V
By alternately supplying group raw materials, crystal growth is performed, competition between group V groups is avoided, and growth conditions suitable for each layer can be selected. Further, it is not the partial pressure of the feedstock that tends to become unstable, but the composition control that can be controlled with high precision, that is, the antimony raw material and the other V group raw materials,
It enables composition control by each supply time.

Thus, in the metalorganic chemical vapor deposition of a compound semiconductor containing ternary or more antimony containing two or more kinds of group V, a conventional problem, that is, a competitive reaction between antimony and other raw materials, It is possible to avoid the problem that it is extremely difficult to improve the quality of the crystal, and it is possible to improve the quality of the compound semiconductor crystal containing antimony grown by using the metal organic chemical vapor deposition method. Become.

[Brief description of drawings]

FIG. 1 is a supply flow chart showing a case of producing an antimony-containing compound semiconductor by a group V alternate supply method of the present invention.

FIG. 2 is a supply flow chart showing a case where an antimony-containing compound semiconductor is produced by inserting a purging time into a group V alternate supply method.

3 is an explanatory diagram for explaining an example of growth of AlAs _0.56 Sb _0.44 according to Example 1. FIG.

FIG. 4 Inserting a purging time in the raw material supply cycle
FIG. 3 is an explanatory diagram for explaining an example of growth of AlAs _0.56 Sb _0.44 .

5 is an explanatory diagram for explaining an example of growth of GaAs _0.51 Sb _0.49 according to Example 3. FIG.

FIG. 6 is a band lineup schematic diagram showing a type-1 structure, a type-2 structure, and a type-3 structure.

FIG. 7 shows a general MOCVD gas supply flow.
It is a supply flow diagram showing a case of producing an antimony-containing compound semiconductor.

[Explanation of symbols]

31, 41, 51 InP substrate 32, 42, 52 InP buffer layer 33, 43 AlAs layer 34,44 AlSb layer 45 Al atomic layer 53 GaAs layer 54 GaSb layer

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Claims (4)

[Claims] 1. At least two kinds of group V raw materials are included,
Antimony-containing III, one of which is antimony
In the method for producing a group V compound semiconductor crystal, a first step of simultaneously supplying a group III source gas and an antimony source gas, and simultaneously supplying the group III source gas and the source gas of a group V element other than antimony The second step is performed alternately and periodically to produce an antimony-containing III-V group compound semiconductor crystal. 2. The method for producing an antimony-containing III-V group compound semiconductor crystal according to claim 1, wherein the first step and the second step are performed by a metal organic chemical vapor deposition method. 3. The antimony according to claim 1, further comprising a third step of supplying only the group III source gas between the first step and the second step. Method for producing contained III-V compound semiconductor crystal. 4. The method for producing an antimony-containing III-V group compound semiconductor crystal according to claim 3, wherein the third step is performed by a metal organic chemical vapor deposition method.