JPS63110718A - Manufacture of epitaxial layer of compound semiconductor - Google Patents

Abstract

PURPOSE:To enable control of film thickness with such precision of layers of several to several ten molecules layers, by piling a group III material of a III-V compound semiconductor on a crystal material of a III-V compound semiconductor substrate so that a laminar state is formed and next making hydride of a group V element be introduced on the piled layer of the group III material and have a surface reaction with the group III element. CONSTITUTION:The amount corresponding to layers of several to several ten molecules of, e.g., Ga is piled in a laminar state on a GaAs substrate crystal material by means of hydrogen reduction and thermal decomposition of alkyl gallium, or evaporation of Ga. Next, e.g., arsine which is a hydride of arsenic is introduced on the Ga piled layer so as to react with Ga. A growth film of a III-V compound semiconductor made of GaAs or the like is obtained by repeating the preceding operations. When hydride of phosphorus is used as this group V hydride, a growth film of e.g., Gap can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a technique for growing a perfect crystal of a group IV compound semiconductor, which allows film thickness control with an accuracy of several angstroms to several tens of angstroms.

(Conventional fL Technique) In order to realize ultra-high-speed semiconductor devices, it is necessary to establish a crystal growth technique for high-purity thin films. Among compound semiconductor crystal growth technologies, molecular beam epitaxy (MBE) and organic gold four-method vapor phase epitaxial growth (MO-CVD) are used for thin film formation, composition control of multi-component mixed crystals, and superlattice creation. It has been widely used. MO-CVD is widely used because its equipment is simple, mass-producible, and has sufficient film control properties for practical use. This is insufficient as a process for ultra-high-speed semiconductor device fabrication that requires. MBE is superior to ViMO-CVD in terms of film thickness control because it uses a method of heating a material and depositing its vapor onto a substrate crystal, and the overall growth rate can be made very small. However, it is difficult to control the film thickness with precision on the order of a monolayer, and R
This problem is finally being solved by HEED monitoring. Furthermore, in MBE, in order to obtain high-quality crystals, it is necessary to set the growth temperature to a very high temperature of 500 to 600° C., making it difficult to realize a steep impurity profile. Furthermore, since MBE is based on a vapor deposition method, problems such as zero val defect, intrusion of crystal defects, and deviation from the stoichiometric composition occur.

On the other hand, molecular layer epitaxy is a method in which a group I compound gas and a group V compound gas are alternately introduced onto a substrate crystal to grow the crystal monolayer by monolayer in the crystal growth of group V compounds (for example, Jun Nishizawa's paper (J, NiN15h
iza, HlAbe and T, Kurabay
ashi;J, Electrochem, Soc, 13
2 (1985) 1197-1200). This method utilizes fist molecule adsorption of a compound gas and obtains a molecular film growth layer by introducing a group (I) compound gas and a group V compound gas once each. Since this method utilizes the molecular adsorption of a compound gas, the growth of low molecular weight layers always occurs even if the pressure of the introduced gas changes. Therefore, a monitor such as RHEED used in MBE is unnecessary. However, since this method grows quasi-molecular layers one by one, it takes a long time to obtain a predetermined film thickness (problem to be solved by the present invention). It is an object of the present invention to provide a novel crystal growth method that overcomes the problems and provides an epitaxial growth method that has film thickness controllability with an accuracy of several minutes + 1 to about 10 molecular layers.

(Means for Solving the Problems) For this reason, the present invention first involves applying an amount of electricity, for example, equivalent to several minutes plus one to several tens of molecular layers, onto a substrate crystal through hydrogen reduction of alkyl gallium, thermal decomposition, or Ga. By vapor deposition,
After depositing a thin film, for example, arsine, which is a hydride of arsenic, is introduced onto the Ga deposited layer and reacted with Ga. By repeating the above operation, a W-V group compound semiconductor such as GaAs can be grown. This is a method for obtaining membranes. If a phosphorus hydride is used as the V source hydride, Gap growth@ can be obtained, for example.

(Function) An explanation will be given by taking as an example the epitaxial growth of GaAs, which is a compound semiconductor containing Ga as a substance belonging to Group I. FIG. 1 shows the principle of epitaxial growth according to the present invention. In FIG. 1, reference numeral 1 indicates a GaAs substrate crystal, reference numeral 2 indicates Ga deposited on the substrate 1, and reference numeral 3 indicates an epitaxial growth layer grown on the substrate 1. As shown in FIG. 1, first, Ga2 was deposited on a GaAs substrate crystal 1 in an amount equivalent to several times +1. Select and deposit. As a method for depositing Ga2, hydrogen reduction of alkyl gallium, thermal decomposition, or Ga vapor deposition is used.

Next, arsine is introduced onto the Ga deposited layer 2, and an epitaxially grown thin film 3 of GaA3 is obtained by the reaction between the introduced arsine and Ga2.By repeating this operation, a GaAs grown layer 3 of a predetermined thickness is obtained. get.

The reaction between Ga, A, and H3 is given by the following equation.

Ga + Ashs → GaA3+, H2 This reaction is 3
Since this occurs even at a low temperature of about 00°C, epitaxial growth of G and A8 is possible even at a low temperature of about 300°C.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2(a) shows an apparatus used in the production method of one embodiment of the present invention by hydrogen reduction of alkyl gallium using MO-CVO9[1 at normal pressure of H1. At one end of the quartz reaction tube 7, a TMG (limethyl gallium) inlet 4, an arsine inlet 5, and a hydrogen inlet 6 are provided.
An exhaust port is provided at the other end. A quartz susceptor 8 that supports GaA and the substrate crystal 1 is provided inside the quartz reaction tube 7, and a GaA susceptor 8 is provided around the quartz reaction tube 7.
, a resistance heating furnace 9 for heating the substrate crystal 1 is provided. In this example, trimethyl gallium (TMG), a type of alkyl gallium, is used as the Ga source.
is used.

The gas introduction method for epitaxial growth is shown in Figure 2 (
Perform the procedure shown in b). That is, T diluted with hydrogen
MG is introduced through the TMG inlet 4, TMG diluted hydrogen is introduced into the quartz reaction tube 7 through the hydrogen inlet 6, and the GaAs substrate t&1 placed on the quartz susceptor 8 is heated in the resistance heating furnace 9. Then, an amount of Ga corresponding to several to about 10 molecular layers is deposited on the surface. Ga to be deposited
The amount of TMG is controlled by the amount of TMG introduced and the time of TMG introduction.Next, the quartz reaction tube 4 is purged with hydrogen gas introduced from the hydrogen inlet 6. Next, arsine diluted with hydrogen is introduced into the quartz reaction tube 7 through the arsine inlet 5 and hydrogen for diluting arsine through the hydrogen inlet 6. The introduction of arsine was carried out on the G,A deposited on the G,A3 substrate 1.
Continue until it reaches s.

By repeating the above operations, it becomes possible to grow a GaAs phosphor crystal thin film.

FIG. 3(a) shows an apparatus used in the manufacturing method of the embodiment of the crystal growth method according to the present invention, which achieves thickness regulation of several molecular layers by thermal decomposition of alkyl gallium. A TMG inlet 10 and an arsine inlet 11 are provided at the upper end of the quartz reaction tube 14, and a vacuum exhaust system 13 is provided at the lower end. Then, inside the quartz reaction tube 14,
Heater 12 for heating GaAs 1 plate crystal 1
is provided. The procedure for growing is shown in Figure 3 (b).
). First, TMG diluted with nitrogen is introduced into the warped quartz tube 14 through the TMG inlet 10, and then
Several molecular layers of Ga are deposited on the surface of the GaAs substrate 1 heated by Step 2.

Next, the introduction of TMG is stopped, and the TMG in the quartz reaction tube 14 is exhausted by the vacuum exhaust system 13. Next, arsine diluted with nitrogen is introduced from the arsine inlet 11, and Ga
The introduction continues until the Ga deposited on the As substrate becomes GaAs. In this example, the amount of Ga deposited by introducing TMG can be precisely controlled by performing the growth in a low vacuum and by using nitrogen instead of hydrogen for diluting the gas.

For the 3rd U (1:), as an example, a GaAs substrate crystal doped with St and having a plane orientation of (100) was used, the substrate temperature was 600°C, the TMG introduction time was 4 seconds, and the TMG exhaust was 10 sec, number of gas introduction cycles and growth when arsine introduction time is 20 seconds and arsine exhaust is 10 seconds
This shows the relationship between Figure 3 (a) assumes that the procedure shown in Figure 3 (b) is one cycle, and plots the grown film thickness against the number of repeated gas introduction cycles. Figure 3 (c)
) It was found from the slope of the graph that a growth film thickness of about 8 times can be obtained with one cycle of gas introduction. This line is GaAs
This corresponds to about 2.8 molecular layers of .

FIG. 4(a) shows an apparatus used in the method of manufacturing a pond according to an embodiment of the present invention using gap deposition. Growth room 2
An arsine supply port 20 is provided on the side wall of the substrate 5, and an arsine introduction nozzle 21 is attached to the tip of the arsine supply port 20 so as to face the -q GaAs substrate crystal 1 which is heated by a heater 12.

Inside the growth chamber 25, a quartz crucible 23 with a heating heater placed therein is provided, and metal gallium 22 is placed therein. A rotary shutter 24 is provided in front of the evaporation port of the crucible 23. Further, a vacuum exhaust system 26 is provided at the bottom of the growth chamber 25. Growth room 25 is the beginning.

The vacuum evacuation system 26 extracts an ultra-high vacuum of 10-" Torr level. The procedure for growth is shown in FIG. 4(b).
Shown below. First, it is heated to 72G by the heating heater 12.
G1 gas generated from heated ca22 in the crucible 23 is deposited on the surface of the aAs substrate crystal 1 by opening the shutter 24. Next, after closing the sieve filter 24, siarsin is introduced through the arsine introduction nozzle 21 to perform epitaxial growth of GaAs. After that, the arsine tX was evacuated.The film thickness controllability obtained by this method was the same as that obtained in the example shown in FIG. 3(a). The degree value was obtained. According to this method, single crystal growth is possible at a substrate temperature of 320° C. or higher. However, the higher the substrate purity, the higher the reaction efficiency of arsine. FIG. 4(C) shows the measurement results of the substrate temperature dependence of the reaction efficiency of arsine. First, Ga was evaporated onto the substrate for 5 minutes, then the substrate temperature was set to a predetermined temperature, and arsine was evaporated for 5 minutes.
X1(r'TarrT: introduced. At this time, %Ga is G
The time required to form aAs was measured, and the reaction efficiency of arsine was calculated. According to this method, epitaxial growth is possible at a low temperature of 300 to 400°C while having a tensile strength of several angstroms. Pilki'
This is an example of an apparatus similar to that shown in FIG. 2(a) when impurity addition is performed with a length of larkM. At one end of the quartz reaction tube 7.

Furthermore, an inlet 30 for %TM, A (remethylaluminum), an inlet 31 for DMZ (dimethylzinc), and an inlet 32 for hydrogen sulfide (H2S) are provided.

AwGMk-XAs growth is T from tf, 4 population 4
MG is introduced and 0 color is deposited on the surface of one substrate crystal 1 as in the case of FIG. 2(a). Next, add TMA to inlet port 3.
0, Atk was deposited in the same manner, and then,
Arsine is introduced through the inlet 5 to obtain an epitaxial thin film of AlxGa5XAs. For the impurity-doped Vi, P type, DMZ diluted with hydrogen is introduced through the inlet 31 into the T
Following the introduction of MA, P-type G&AS and P-type A
1. x Ga1-xls is obtained. For n-type, hydrogen sulfide diluted with hydrogen is introduced from the inlet 32 before introducing arsine, and n-type GaAs and n-type AtX Ga1-
Obtaining XAs - FIG. 5 FIGS. 5(b) and 5(e), similar to FIG. 5(&), are examples of an apparatus for doping impurities during epitaxial growth of AlxGa1-XAs. Fig. 5(b) shows a device similar to Fig. 3(&), with h, Sarani, TMA+7)4
Population 40, DMZ inlet 41, sulfurized water inlet 42
are provided, and each gas diluted with nitrogen is supplied to the gas shown in Figure 5 (&
); introduce in the ridge, P-type and n-type Ga
Obtain a base of Aa and AlxGa1-XAs. Figure 5 (
C) is an apparatus similar to that shown in FIG. 4 (ml), in which a hydrogen sulfide introduction port 50 is further provided on the side wall of the growth chamber 25, and a hydrogen sulfide introduction nozzle 51 is heated at the tip thereof.

Inside the growth chamber 25, an aluminum heating crucible 53 and a sulfur heating crucible 56 are further provided, in which metal aluminum 52 and metal sulfur 55 are placed. 9. Rotary shutters 54 and 57 are provided in front of the evaporation ports of crucibles 53 and 56. The gas introduction procedure was carried out in the same manner as shown in FIG. 5(a).2. Single-crystal GaAa and ALxGal-XAB thin films of n-type T10''Cm' were obtained from those of P type with a carrier density of tO''Cm-'.

Figure 6 shows an example of an apparatus for epitaxial growth of InGaA and P, which are quaternary mixed crystals. ), and a phosphine introduction nozzle 61 is installed at its tip.
3 is provided, and metal indium 62 is placed therein.

In addition, in front of the evaporation port of the melting port 63, there is a rotary shutter 64.
is provided. First, gallium 22 was deposited on the surface of the GaAs substrate crystal 1, then indium 62 was deposited, and then arsine and phosphine gold were introduced through the introduction nozzles 22 and 61 to obtain an epitaxially grown InGaAsP thin film.

(Effects of the Invention) As has been explained above, the crystal growth method of the present invention utilizes the warpage of a substance belonging to the subgroup of Ga and a group V hydride of arsine, for example, and alternately attaches these to a substrate. By introducing it onto the crystal, it is possible to
This is a method for manufacturing an epitaxial layer of a l-V group compound semiconductor, which allows film thickness control in units of angstroms.

However, the reaction between Ga and arsine occurs at a low temperature of 320°C, and low-temperature growth is an OT capability, making it industrially valuable (
It is highly direct.

Furthermore, AtxGal-xA, which is a ternary and quaternary mixed crystal,
3 and InGaAsP can also be grown, and impurity addition can be performed, so it can be used for semiconductor lasers, HEMTs, FETs.
It is a method of manufacturing optical detectors, etc., which has a high value.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of epitaxial growth of the present invention, FIGS. 2(a), 3(a) and 4(a) are sectional views showing an example of a GaAs epitaxial growth apparatus. Figure 3 (b) and Figure 4 (with) are explanatory diagrams of the steps of each crystal growth method, Figure 3 (e) is a graph showing the relationship between the number of gas introduction cycles and the grown film thickness, and Figure 4 (e) is a graph showing the substrate temperature dependence of the reaction efficiency of arsine;
a), Fig. 5) and Fig. 5(e) show 7
'j A sectional view showing an example of an AtxGal-X As epitaxial growth apparatus. FIG. 6 is a sectional view of an example of a 1nGaAsP epitaxial growth apparatus. 1 a GaAs substrate crystal 2: Gallium 3: Epitaxial growth layer 3: Epitaxial growth thin film 4: T
MG inlet 5: Arsine inlet 6: Hydrogen inlet 7.
14: Quartz reaction tube 8: Quartz susceptor 9: Resistance heating furnace 10: TMG inlet 11: Arsine inlet 1
2: Heater for heating 13.26: Vacuum exhaust system 20: Arsine supply port 21: Arsine introduction nozzle 22: Metallic gallium 23: Quartz crucible for heating gallium 24.5
4.57.64: Rotating shutter 25: Growth chamber 30
．． 40: TMA inlet 31.41: DMz inlet 32.42.50: Hydrogen sulfide inlet 51: Hydrogen sulfide inlet nozzle 52: Metal aluminum 53 Nialuminum heating crucible 55: Metal sulfur 56: Sulfur heating crucible 60: Phosphine inlet 61: Phosphine introduction nozzle 62: Indium metal 63: Indium heating crucible Patent applicant New Technology Development Corporation (and 2 others) Applicant's agent Patent attorney Fumi Sato (Figure 1, Figure 2) a) Figure 2 (b) Figure 3 (b) Figure 3 (e) Number of gas introduction cycles Figure 4 (a) Figure 4 (b) Figure 4 (c) Substrate temperature (℃) [1000/ T ] lE 5 Figure (a) Figure 5 (c) Figure 6

Claims (8)

[Claims] (1) A group III material of a group III-V compound semiconductor is deposited in the form of a thin film on a III-V group compound semiconductor substrate crystal, and then a hydride of a group V element is introduced onto the group III material deposited layer to A method for producing an epitaxial layer of a compound semiconductor, which comprises performing a surface reaction with a group substance and repeating the above operations to obtain an epitaxial layer of a III-V compound semiconductor in several to several tens of molecular layers. (2) The Group III substance is deposited in a thin film on the III-V compound semiconductor substrate crystal by hydrogen reduction or thermal decomposition of an alkylated Group III substance, or by vapor deposition of the Group III substance. A manufacturing method according to claim 1. (3) The manufacturing method according to claim 1 or 2, characterized in that gallium is used as the Group III substance and arsine or phosphine is used as the hydride of the Group V element. (4) The manufacturing method according to claim 1 or 2, characterized in that a ternary or quaternary group III-V mixed crystal is grown using a plurality of group III-V atoms or compounds. . (5) Group III-V mixed crystal is Al_XGa_1_-_XAs
The manufacturing method according to claim 4, characterized in that: (6) The manufacturing method according to claim 4, wherein the III-V group mixed crystal is InGaAsP. (7) III-V by atoms or compounds of group II or group VI
7. The manufacturing method according to claim 1, wherein an impurity is added to an epitaxial layer of a group compound semiconductor. (8) The manufacturing method according to claim 7, characterized in that zinc is used as the Group II substance and sulfur is used as the Group VI substance.