JP2620546B2 - Method for producing compound semiconductor epitaxy layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a perfect crystal growth of a III-V compound semiconductor capable of controlling the film thickness at a low temperature and with a precision of several Angstroms to several tens Angstroms using a photochemical reaction. About technology.

(Prior Art) In order to realize an ultrahigh-speed semiconductor device, it is necessary to establish a crystal growth technique for a high-purity thin film. Among compound semiconductor crystal growth technologies, molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MO-CVD) are widely used for thin film formation, composition control of multi-element mixed crystals, and superlattice fabrication. I came. MO-CVD has the simplicity of equipment, mass productivity, and sufficient film thickness controllability for practical use to a certain extent, but ultra-high-speed semiconductor devices that require film thickness control with an accuracy on the order of a monolayer. It is insufficient as a manufacturing process.
MBE uses a method in which a metal material, which is a component of a semiconductor, is heated and its vapor is vapor-deposited on a substrate crystal.
It is superior to MO-CVD. However, it is difficult to control the film thickness with an accuracy of the order of a monolayer, and this problem is finally being solved by monitoring with RHEED. Further, in MBE, it is necessary to set the growth temperature to a high temperature of 500 to 600 ° C. in order to obtain a good quality crystal, which causes a problem such as redistribution of the produced impurity profile. Furthermore, MBE is based on a vapor deposition method, in which crystal defects such as oval defects are inserted,
Problems arise, such as deviations from the stoichiometric composition.

On the other hand, molecular layer epitaxy is a method in which a group III compound gas and a group V compound gas are alternately introduced onto a substrate crystal in the crystal growth of a group III-V compound semiconductor, and the crystal is grown in monolayers (for example, , Junichi Nishizawa's paper (J. Nish
izawa, H. Abe and T. Kurabayashi; J. Electrochem. Soc. 1
32 (1985) 1197-1200]. In this method, a monomolecular film growth layer is obtained by introducing a group III compound gas and a group V compound gas once each by utilizing the single molecule adsorption of a compound gas. Since this method utilizes the monomolecular adsorption of the compound gas, the growth of the monomolecular layers always occurs even if the pressure of the introduced gas changes. Therefore, a monitor such as RHEED used in MBE is unnecessary. However, this method has a disadvantage that it takes a long time to obtain a predetermined film thickness because the growth is performed for each monolayer.

(Problems to be Solved by the Invention) The present invention is a novel crystal growth method for overcoming the problem of upward molecular layer epitaxy, and has an accurate film thickness controllability from several molecular layers to about 10 molecular layers. And an epitaxial growth method characterized in that the crystal growth temperature is lowered by utilizing an optical reaction.

(Means for Solving the Problems) For this reason, the present invention first includes a group III element corresponding to several to several tens of molecular layers on a substrate crystal, the group III element being accompanied by ultraviolet irradiation. A gas reduction reaction between a gas and hydrogen as a carrier gas, a reaction with an inert carrier gas, a vapor phase pyrolysis reaction or a thin film formed by vapor deposition of a group III substance, and then a hydride of a group V element is converted into a group III substance. It is introduced onto the material deposition layer and undergoes a surface reaction with a group III material under ultraviolet irradiation. For example, Ga is deposited in the form of a thin film by a hydrogen reduction reaction of alkyl gallium, a gas phase pyrolysis reaction with an inert gas such as nitrogen, or vapor deposition of Ga, and then, for example, arsenic, which is a hydride of arsenic, is treated with Ga. Introduced on the deposition layer and reacted with Ga and AsH ₃ with ultraviolet light irradiation, III
This is a method for obtaining a group V compound semiconductor. If phosphorus hydride is used as the group V hydride, for example, a GaP grown film can be obtained.

(Effect) The epitaxial growth of GaAs among compound semiconductors containing Ga as a substance belonging to Group III will be described as an example. FIG. 1 is a diagram showing the principle of epitaxial growth according to the present invention. In FIG. 1, reference numeral 1 denotes a GaAs substrate crystal, reference numeral 2 denotes Ga deposited on the substrate 1, reference numeral 3 denotes an epitaxially grown layer grown on the substrate 1, reference numeral 4 denotes a first light, and reference numeral 5 denotes a second light. Indicates light. As shown in FIG. 1, first, Ga
On the As substrate crystal 1, Ga2 is selected and deposited in an amount corresponding to several angstroms to several tens angstroms. At this time, the surface of the substrate 1 is irradiated with the first light indicated by reference numeral 4 to cause a hydrogen reduction or thermal decomposition reaction of the alkyl gallium at a low temperature to deposit Ga 2 on the surface of the substrate 1. Alternatively, Ga2 is deposited by vapor deposition of Ga. The amount of Ga deposited is
The film thickness is controlled so as to be a predetermined film thickness by the supply amount and the supply time of the alkyl gallium or Ga vapor. Next, while irradiating the surface of the substrate 1 with the second light indicated by reference numeral 5,
Arsine (AsH ₃ ) is introduced onto the Ga deposition layer 2 to obtain a GaAs epitaxial growth layer 3 on the GaAs substrate crystal 1 at a low temperature.
By repeating this operation, the GaAs growth layer 3 of a predetermined film layer can be obtained while having an arbitrary film thickness controllability in the range of several angstroms to several tens angstroms. When alkyl gallium is used, the light is excimer laser light, ArF: 193 nm, KrF: 249 nm or mercury lamp light, and the light is ArF: 193 nm, KrF: 249 nm, or mercury lamp light.

This allows the reaction between Ga and AsH ₃ Can occur at room temperature, and epitaxial growth of GaAs is possible even at room temperature.

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 in which an alkyl gallium is reduced with irradiation of ultraviolet light using an atmospheric pressure MO-CVD apparatus. At one end of the quartz reaction tube 9, a TMG (trimethylgallium) inlet 6, an arsine inlet 7, and a hydrogen inlet 8 are provided, and at the other end, an exhaust port is provided. A quartz susceptor 10 for supporting the GaAs substrate crystal 1 is provided inside the quartz reaction tube 9, and a GaAs susceptor 10 is provided around the quartz reaction tube 9.
A resistance heating furnace 11 for heating the substrate crystal 1 is provided. In this embodiment, trimethylgallium (TMG), which is a kind of alkyl gallium, is used as a source of Ga. The epitaxial growth is performed according to the procedure shown in FIG. That is, while irradiating the light (excimer laser light ArF: 193 nm, KrF: 249 nm or a mercury lamp) indicated by the reference numeral 4 on the GaAs substrate crystal 1, the TMG diluted with hydrogen is introduced into the TMG inlet 6, and the hydrogen is introduced into the hydrogen inlet The GaAs substrate crystal 1 mounted on the quartz susceptor 10 is heated by the resistance heating furnace 11 and Ga is deposited from several angstroms to several ten angstroms on the surface thereof. The amount of Ga to be deposited is controlled by the TMG introduction amount, TMG introduction time, and light intensity. Next, the quartz reaction tube 9 is purged with hydrogen introduced from the hydrogen inlet 8. Then, while irradiating the light (excimer laser light ArF: 193 nm, KrF: 249 nm or a mercury lamp) indicated by the reference numeral 5 on the GaAs substrate crystal 1, arsine diluted with hydrogen was introduced into the quartz reaction tube through the arsine inlet 7. 9 The introduction of arsine is continued until Ga deposited on the GaAs substrate 1 becomes GaAs. Although GaAs epitaxial thin films can be obtained at room temperature by light irradiation, high-purity GaAs epitaxial growth layers can be obtained at 300 ° C. or higher.

FIG. 3 (a) shows a crystal growth according to the present invention in which the thickness controllability of several molecular layers (5 to 10 angstroms) is realized by a gas phase thermal decomposition reaction between alkyl gallium and an inert carrier gas under ultraviolet irradiation. 7 shows an apparatus used in a manufacturing method according to another embodiment of the present invention. At the upper end of the quartz reaction tube 9, TM
A G inlet 20 and an arsine inlet 21 are provided, and a vacuum exhaust system 23 is provided at the lower end. A heating heater 22 for heating the GaAs substrate crystal 1 is provided inside the quartz reaction tube 9. FIG. 3 (b) shows the procedure of crystal growth.
Shown in First, light indicated by reference numeral 4 (excimer laser light)
ArF: 193 nm, KrF: 249 nm or a mercury lamp) is irradiated onto the GaAs substrate crystal 1 while diluting with nitrogen to introduce TMG into the TMG inlet.
Ga is introduced into the quartz reaction tube 9 from 20 and several molecular layers (5 to 10 angstroms) of Ga are deposited on the surface of the GaAs substrate 1 heated by the heater 22. Next, stop introducing TMG,
The TMG inside the quartz reaction tube 9 is evacuated by the vacuum evacuation system 23.
Then, the light indicated by reference numeral 5 (excimer laser light ArF:
193 nm, KrF: 249 nm or mercury lamp) GaAs substrate crystal 1
While irradiating the above, arsine diluted with nitrogen is introduced from the arsine inlet 21 to obtain a GaAs epitaxially grown thin film. In the present embodiment, by performing growth in a low vacuum and using nitrogen instead of hydrogen for gas dilution, the amount of Ga deposited by introducing TMG can be precisely controlled. In addition, by irradiating light, Ga is deposited at a temperature higher than room temperature only at a place where the light is irradiated, and Ga and arsine can be reacted at a temperature higher than room temperature by irradiating light. GaAs can only be epitaxially grown.

FIG. 4 (a) shows an apparatus used in a manufacturing method according to another embodiment of the present invention utilizing vapor deposition of Ga. An arsine supply port 30 is provided on the side wall of the vacuum chamber 35, and an arsine introduction nozzle 31 is attached at the tip thereof so as to face the GaAs substrate crystal 1 heated by the heater 22. Inside the vacuum chamber 35, a quartz crucible 33 having a built-in heating heater is provided, in which a metal gallium 32 is put. In addition, a shutter 34 is provided in front of the evaporation port of the crucible 33. Further, a vacuum exhaust system 26 is provided below the vacuum chamber 35. The vacuum chamber 35 is initially evacuated to an ultra-high vacuum (~ 10
^-10 Torr). FIG. 4 (b) shows the procedure of crystal growth.
Shown in First, the Ga heated by the substrate heating heater 22
On the As substrate crystal 1, a vapor of Ga generated from the heated Ga 32 in the crucible 33 is vapor-deposited by opening the shutter. next,
After the shutter 34 is closed, light (excimer laser light ArF: 193 nm, KrF: 249 nm or a mercury lamp) indicated by reference numeral 5 is applied to Ga.
While irradiating onto As substrate crystal 1, arsine introduction nozzle 31
More arsine is introduced and GaAs is epitaxially grown. Thereafter, the arsine is evacuated. The thickness controllability of the crystal growth method by this method is from several angstroms to several
10 angstroms. In this way, it is possible to epitaxially grow GaA ₃ at temperatures above room temperature by irradiation of light. However, a high-purity GaAs epitaxially grown thin film is easily obtained at a substrate temperature of 300 ° C. or higher.

FIG. 5 (a) is an embodiment of the same apparatus as that of FIG. 2 (a) in the case where impurities are added by epitaxial growth of Al _X Ga _{1 -X} As. At one end of the quartz reaction tube 9, an inlet 41 for TMA (trimethylaluminum), an inlet 42 for DMZ (dimethylzinc), and an inlet 43 for hydrogen sulfide (H ₂ S) are further provided. In the growth of Al _X Ga _{1 -X} As, first, TMG was introduced while irradiating the light (excimer laser light ArF: 193 nm, KrF: 249 nm or a mercury lamp) indicated by reference numeral 4 onto the GaAs substrate crystal 1. 2 Ga is deposited on the surface of the GaAs substrate crystal 1 as in the case of FIG. Next, the light indicated by reference numeral 40 (excimer laser light ArF: 193 nm, KrF: 249 nm or a mercury lamp)
While irradiating the GaAs substrate crystal 1, TMA is introduced from the TMA inlet 41, and Al is deposited in the same manner. Then, while irradiating the light indicated by the reference numeral 5 on the GaAs substrate crystal 1, the arsine inlet 7 is irradiated. More arsine is introduced to obtain an Al _X Ga _1-X As epitaxial thin film. As for the impurity addition, for the p-type, DMZ diluted with hydrogen is introduced from the inlet 42 following the introduction of TMA to obtain p-type Al _X Ga _{1 -X} As. When introducing DMZ, light or light is irradiated to control the impurity density. For n-type, hydrogen sulfide diluted with hydrogen
To obtain n-type Al _X Ga _{1 -X} As. At the time of introduction of hydrogen sulfide, light is irradiated to control the impurity density.

Figure 5 (b) and FIG. 5 (c), like the FIG. 5 (a), in an embodiment of the apparatus in the case where an impurity in the epitaxial growth of using light irradiation Al _X Ga _1-X As is there. FIG. 5 (b) shows a device similar to that of FIG. 3 (a). At the upper end of the quartz reaction tube 9, an inlet 50 for TMA, an inlet 51 for DMZ, and an inlet 52 for hydrogen sulfide are further provided. Then, gases diluted with nitrogen are introduced in the same manner as in the embodiment of FIG. 5 (a) to obtain growth of p-type and n-type Al _X Ga _{1 -X} As. FIG. 5 (c) shows a device similar to that of FIG. 4 (a). A hydrogen sulfide inlet 60 is further provided on the side wall of the vacuum chamber 35, and a hydrogen sulfide inlet nozzle 61 is provided at the tip thereof. Installed. Inside the vacuum chamber 35, an aluminum heating crucible 63 and a sulfur heating crucible 66 are further provided, in which metal aluminum 62 and metal sulfur 65 are put. In addition, a shutter 64 is provided in front of the evaporation ports of the crucibles 63 and 66.
67 are provided. The gas introduction procedure was performed in the same manner as in FIG. 5 (a). From the p-type carrier density of 10 ²⁰ cm ⁻³ to n,
Single crystal GaAs and Al _X Ga _1-X As thin films of 10 ¹⁹ cm ^-3 were obtained.

In the above description, mainly the case of gallium as a group III substance and arsenic as a group V substance has been described, but in the case of other group III substances, for example, indium, and other group V substances, for example, phosphorus Can also be applied in the production method of the present invention. Also, for example, the quaternary III of InGaAsP
The method of the present invention can be applied to the case of a -V group mixed crystal.

(Effect of the Invention) As described above, the crystal growth method of the present invention utilizes the reaction between a substance belonging to Group III of Ga and a hydride of Group V of arsine, for example, to form a deposition reaction and deposition of Ga. Excitation of the reaction between Ga and arsine by excimer laser light or mercury lamp light to control the film thickness from several angstroms to several tens of angstroms. It is a manufacturing method of. Further, the reaction between Ga and arsine can be caused even at room temperature by light irradiation, and low-temperature growth is possible, which is industrially valuable.

Further, it is possible to grow Al _X Ga _{1 -X} As, which is a ternary mixed crystal, and it is possible to add impurities, so that a semiconductor laser,
It is a valuable method for manufacturing HEMTs, FETs, super-elements, etc.

[Brief description of the drawings]

FIG. 1 is a principle view of the epitaxial growth of the present invention, FIG. 2 (a), FIG. 3 (a) and FIG. 4 (a) are sectional views showing an example of a GaAs epitaxial growth apparatus, FIG. Third
4 (b) and FIG. 4 (b) are explanatory views of the procedures of the respective crystal growth methods, and FIGS. 5 (a), 5 (b) and 5 (c) show impurity-doped Al _X Ga. FIG. 3 is a cross-sectional view illustrating an example of a _1-X As epitaxial growth apparatus. 1: GaAs substrate crystal, 2: gallium, 3: epitaxial growth layer, 4: first light, 5: second light, 6, 20: TMG inlet,
7, 21: Arsine inlet, 8: Hydrogen inlet, 9: Quartz reaction tube, 10: Quartz susceptor, 11: Resistance heating furnace, 22: Heater, 23, 26: Vacuum exhaust system, 30: Arsyl supply port , 31: Arsine introduction nozzle, 32: Metallic gallium, 33: Quartz crucible, 3
4, 64, 67: shutter, 35: vacuum chamber, 40: light, 4
1, 50: TMA inlet, 42, 51: DMZ inlet, 43, 52, 60:
Hydrogen sulfide inlet, 61: hydrogen sulfide inlet nozzle, 62: metal aluminum, 63: aluminum heating crucible, 65: metal sulfur, 66: sulfur heating crucible

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Kurabayashi 7-25 Kasumicho, Yagiyama, Sendai City (56) References JP-A-61-34927 (JP, A) "Technical Research Report of the Institute of Electronics and Communication Engineers" Vol. 184, no. 127, SSD84-55 "MOLECULAR LAYER EPI TAXY" (August 27, 1984)

Claims (8)

(57) [Claims] 1. A controlled amount of I in a group III-V compound semiconductor.
A III-V compound semiconductor is obtained by subjecting a group II substance to a hydrogen reduction reaction between a gas containing a group III element and hydrogen as a carrier gas, a gas phase thermal decomposition reaction by a reaction with an inert carrier gas, or a vapor deposition of a group III substance. A thin film is deposited on the substrate crystal, and then a hydride of a group V element is introduced while irradiating light onto the group III substance deposition layer to cause a surface reaction with the group III substance previously deposited by a photochemical reaction. A method of manufacturing an epitaxial layer of a compound semiconductor, comprising obtaining an epitaxial layer of a group III-V compound semiconductor by repeating the above operation. 2. A method for depositing a group III substance on a crystal of a group III-V compound semiconductor substrate in the form of a thin film while irradiating light.
2. The method for producing an epitaxial layer of a compound semiconductor according to claim 1, wherein the method is carried out by hydrogen reduction or gas phase thermal decomposition of an alkylated group I substance. 3. A compound semiconductor according to claim 1, wherein the group III substance is deposited on the crystal of the group III-V compound semiconductor substrate in the form of a thin film by vapor deposition of the group III substance. Layer manufacturing method 4. The epitaxial layer of a compound semiconductor according to claim 1, wherein gallium is used as a group III substance, and arsine or phosphine is used as a hydride of a group V element. Production method 5. A ternary or quaternary group III-V mixed crystal is grown by a plurality of group III-V atoms or compounds. For manufacturing epitaxial layers of some compound semiconductors 6. The method for producing an epitaxial layer of a compound semiconductor according to claim 5, wherein the group III-V mixed crystal is Al _X Ga _{1 -X} As. 7. The method according to claim 1, wherein an impurity is added to the epitaxial layer of the group III-V compound semiconductor by using a group II or group VI atom or compound. Method for producing compound semiconductor epitaxial layer 8. The method according to claim 6, wherein zinc is used as a group II substance and sulfur is used as a group VI substance.