JPH1098000A - Epitaxial growth system for semiconductor crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system which can uniformly grow a thin film on a substrate with a high step coverage and is suitable for growing a thin film on the side wall of a recessed or projecting section, and then, can grow a semiconductor crystal having high crystallinity at a low temperature by preventing the redistribution of impurities. SOLUTION: At the time of growing a semiconductor crystal on a crystalline substrate 3 one monomolecular layer by one monomolecular layer by guiding gas introducing nozzles 11-13 closely to the substrate 3 and alternately blowing gaseous starting materials from gas ports 11d-11f in pulse-like states, the nozzles 11-13 adjusted so that the conductances from a gas introducing port 11g to the gas ports 11 can become equal to each other and, at the same time, the nozzles 11-13 are made of a transparent material. In addition, the front end section of each gas port is formed in a flat shape so that at leaks one kind of gaseous starting material 'can be excited by light by projecting light having a prescribed wavelength upon the gas before the gas reaches the pipe-like gas port of the corresponding nozzle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for epitaxially growing a semiconductor crystal, and more particularly to an apparatus for epitaxially growing a semiconductor crystal in a evacuated growth chamber.

[0002]

2. Description of the Related Art Conventionally, as a method for epitaxially growing a semiconductor crystal, a vapor phase method in which the semiconductor crystal is grown under a normal or reduced pressure atmosphere is widely known. Although the gas phase method has a simple apparatus and is excellent in mass productivity, there is a limit in controlling the film thickness, so that the film thickness controllability on the order of a single molecule is not provided. For this reason, ultrahigh-frequency devices such as electrostatic induction transistors (SIT) that can operate in the terahertz band and superlattice (SL) devices require the control of the film thickness on the order of single molecules, and therefore, the conventional gas phase method. Some were difficult to manufacture.

On the other hand, an epitaxial growth method of growing in a high vacuum, for example, molecular beam epitaxy (MBE)
Is capable of controlling the film thickness on the order of angstroms, is suitable for the manufacture of the device requiring a high degree of film thickness control, and various studies have been conducted for practical use.
In the MBE, a source material is heated and evaporated to form a source gas, and molecules of the source gas are deposited in a beam form on a substrate, thereby performing epitaxial growth. In this case, the motion of the incident molecular beam in a high vacuum has a strong directivity, and the growth on a large-area substrate tends to be non-uniform. Although a method for improving the performance is adopted, the entire device becomes complicated and expensive. Also, if a molecular beam incident on the substrate is blocked by a shield, crystal growth cannot be performed in the shielded portion of the substrate. On the other hand, crystal growth is not performed at all on the substrate portion, particularly the side wall portion, which is shielded by the unevenness, or the crystal growth becomes extremely uneven. This is the same in MO-MBE using an alkyl metal compound that is a gaseous molecule at room temperature.

Further, molecular layer epitaxy (ML), which is one of epitaxial growth methods for growing in a high vacuum.
E) is a method in which a group III compound gas and a group V compound gas are alternately introduced onto a crystal substrate in the crystal growth of a group III-V compound, and the crystal is grown in monomolecular layers (for example, Junichi Nishizawa et al. Dissertation (J. Nishizawa, H. Abe and T. Kura
bayashi; J. Electrochem. Soc. 132 (1985) pp1197〜12
00]). According to this method, a compound gas is adsorbed and a surface reaction is utilized.
A monomolecular film growth layer can be obtained by introducing the group compound gas and the group V compound gas once each. This is due to the fact that monomolecular layer growth always occurs within a certain pressure range even when the pressure of the introduced gas changes, because monolayer adsorption of the compound gas is used. According to this method, in the GaAs crystal growth,
The conventional alkyl gallium, trimethylgallium (TM
G) and arsine (AsH ₃ ) which is a hydrogen compound of arsenic
However, by using triethylgallium (TEG), which is an alkyl gallium, instead of TMG, a high-purity GaAs growth layer can be obtained by growth at a lower temperature (for example, J. Nishizawa et al. [J. Nishizawa et al. ,
H. Abe, T. Kurabayashiand N. Sakurai; J. Vac. Sci.
Technol.A Vol. 4 (3), (1986) pp. 706-710]). According to this method, a high-purity single crystal thin film having a flat surface can be obtained at a growth temperature of about 300 ° C.

[0005]

The above-mentioned M
In order to obtain good quality crystals by BE, a growth temperature of 50
Although it is necessary to set the temperature to a high temperature of 0 to 600 ° C., when realizing a steep impurity profile, redistribution of the impurity profile due to a high growth temperature becomes a problem. In addition, since it is based on the vapor deposition method, problems such as deviation from the stoichiometric composition of the grown film and generation of crystal defects such as oval defects also occur.

On the other hand, it is clear that the MLE can grow at a lower temperature than the MBE and is also excellent in the controllability of the film thickness. However, the MLE has some problems as described below. I have. That is, in MLE, the growth of a monomolecular layer is fundamental, so that the crystal growth is uniform. For example, in the growth of Al _x Ga _{1 -x} As, which is one of the ternary compound semiconductors, trimethylgallium is used as a group III alkyl metal compound. (TMG) and trimethyl aluminum (TMA)
However, arsine (AsH ₃ ) is used as a group V hydrogen compound. When a methyl-based alkyl metal compound is used, the dependence of the growth thickness on the plane orientation of the crystal substrate increases. For example, even if a single molecular layer is grown on the (100) plane, (111) of the side wall of the groove provided on the (100) plane
It may not grow on other plane orientations, such as a plane, or the growth rate may be very low. Further, when an ethyl-based alkyl metal compound such as triethylaluminum (TEA) or triethylgallium (TEG) is used, the dependence on the plane orientation is small and is almost eliminated under certain conditions. Sex will be expressed. Further, when the directivity of the incident direction of the gas molecules is lost, the gas molecules collide with the inner wall of the vacuum vessel and release impurities, so that the purity of the formed film is reduced.

In view of the above, the present invention has been made in consideration of the above-described MLE.
In the case of a large area substrate or a substrate having irregularities, it is possible to grow a thin film uniformly and with good step coverage on these substrates, particularly to a side wall portion formed by a concave portion or a convex portion. It is an object of the present invention to provide an apparatus for epitaxially growing a semiconductor crystal which is effective for growing a thin film, prevents redistribution of impurities, and is capable of low-temperature crystal growth having good crystallinity.

[0008]

The above object is achieved by the present invention.
According to the invention described in the above, from each of the source gas sources of a plurality of types of source gases provided outside the growth chamber, a nozzle for introducing a gas is introduced to the vicinity of the crystal substrate installed in the evacuated growth chamber. In a device in which each source gas is alternately ejected in a pulsed manner from each gas ejection port of a nozzle to epitaxially grow a semiconductor crystal on a crystal substrate by a single molecular layer, the nozzle is connected to a plurality of gas ejection ports from a gas introduction port. And the nozzles are formed transparent, and the tips of a plurality of gas outlets are formed in a flat shape, and at least one type of source gas is ejected from the gas outlets. This is achieved by previously irradiating the transparent nozzle with light of a predetermined wavelength to excite the source gas.

Further, according to the second aspect of the present invention,
It has a disc-shaped nozzle made of a material that transmits light, and a plurality of pipe-shaped gas ejection ports provided on the lower surface of the disc-shaped nozzle. The material gas is light-excited by irradiating the nozzle with light having a predetermined wavelength before jetting from the outlet.

According to the present invention, the source gas is ejected from a plurality of directions toward the crystal substrate while having directivity through a plurality of flat gas ejection ports, and reaches the crystal substrate directly. Therefore, a uniform supply of the source gas can be performed as compared with the conventional case where the source gas is introduced from one direction, so that a uniform step coverage can be easily obtained even on a large-sized crystal substrate, and impurities from the inner wall of the vacuum vessel can be obtained. No contamination. Thus, according to the present invention, it is possible to control the thickness of the semiconductor crystal thin film on the order of a single molecule, and since no directivity is exhibited, the uniformity can be obtained even on a large-area crystal substrate having an uneven portion. High-purity crystal growth is possible.

Further, according to the present invention, before the source gas is ejected from the pipe-shaped gas outlet, the source gas is irradiated with light having a predetermined wavelength, whereby the gas molecules of the source gas are turned into a radical state by photoexcitation. Therefore, molecular layer epitaxy using molecules in a radical state becomes possible, and crystal growth at a lower temperature becomes possible. For this reason, the nozzle is made of a material that is transparent to infrared light, visible light, and ultraviolet light with respect to the wavelength of the light to be used, and is irradiated with light in a region where gas molecules in front of the gas ejection port are present at a high concentration. At the same time, the light transmitted through the transparent nozzle is irradiated on the surface of the crystal substrate for crystal growth,
The surface reaction can be photoexcited. Therefore, according to the present invention, the crystal growth temperature can be lowered by efficiently photo-exciting the source gas molecules and, at the same time, photo-exciting the surface reaction on the crystal substrate, and the epitaxial growth of a good-quality semiconductor crystal can be performed. A device could be provided.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to an embodiment shown in the accompanying drawings when the present invention is applied to an MLE of a group III-V compound semiconductor, for example, Al _x Ga _{1 -x} As. explain. FIG. 1 shows an embodiment of a molecular layer epitaxy (MLE) apparatus for carrying out the present invention. The MLE apparatus 1 is basically provided to hold a crystal growth chamber 2 capable of maintaining the inside in an ultra-high vacuum and a crystal substrate 3 for growing a semiconductor crystal in the crystal growth chamber 2. The quartz susceptor 4 and a source gas, that is, an element necessary for a crystal to be grown, in this case, gallium (Ga),
A gas introduction unit 5 for introducing a gas or a gaseous compound containing aluminum (Al) and arsenic (As) into the crystal growth chamber 2, and the inside of the crystal growth chamber 2 through a gate valve 6. For example, a cooling trap for evacuating to a vacuum,
It includes a vacuum evacuation system 7 composed of a cryopump, a turbo molecular pump, and the like, and a lamp chamber 9 provided above the crystal growth chamber 2 and having a built-in infrared lamp 8 for heating a substrate.

The gas introduction unit 5 includes three nozzles 11 made of, for example, quartz, Pyrex glass, stainless steel, etc., which are disposed toward the crystal substrate 3 in the crystal growth chamber 2, respectively.
12 and 13 and each nozzle 11, 12, 13
Are flow control mechanisms (CTL) 11a, 12a,
It is connected to a compound gas cylinder (not shown) containing gallium (Ga), aluminum (Al), and arsenic (As) via 13a and valves 11b, 12b, and 13b. The flow rate adjusting mechanisms 11a, 12a, and 13a are controlled by the gas introduction mode control system 14 as shown in a time chart of FIG. 2, for example, so that the flow rate and the introduction time of the source gas introduced into the crystal growth chamber 2. Can be appropriately controlled.

Each of the nozzles 11, 12, and 13 has the same shape, and a gas ejection port shown in FIG. 6 is connected to each tip. In the conventional MLE device, the gas ejection port is shown in FIG.
Was provided with one gas ejection port 11c as shown in FIG.
According to the present invention, the nozzle 11 includes, for example, three pipe-shaped gas outlets 11d, 11e, and 11f each opening toward the crystal substrate 3, as shown in FIG. As shown in FIG. 6, a flat structure is formed.
Each gas outlet 11d, 11e, 11f has the same length, but is formed to have an appropriate thickness so that the conductance from the gas inlet 11g is equal. Pipe-shaped gas outlet 11
It is configured such that the same amount of source gas from d, 11e, and 11f is introduced.

Further, as shown in FIG. 5, for example, as shown in FIG. 5, the nozzle 11 forms a pipe-shaped gas ejection port for ejecting a plurality of gases inside the annular passage 11h, that is, a pipe portion 11i.
The thickness of 1i is selected such that the same amount of source gas is introduced through them. The shape of the gas outlet is
As shown in FIG. 6, it is formed in a flat structure. As a result, the distribution of the source gas on the crystal substrate 3 becomes more uniform, and even when a large-area crystal substrate is used, uniform step coverage can be obtained over the entire substrate.
As shown in FIG. 6, the tip of the pipe-shaped gas jet is flattened in a laterally crushed or elliptical shape, and the gas ejected from the pipe-shaped gas jet is formed by this flat shape. By spreading the molecules in the lateral direction, the in-plane distribution of the gas supplied onto the crystal substrate 3 becomes more uniform, and it becomes possible to grow crystals on a crystal substrate having a larger area.

The embodiment according to the present invention is configured as described above, and using this MLE apparatus 1, Al _x Ga _{1 -x}
When the As crystal is grown, the following procedure is performed. First, set the crystal substrate 3 on the quartz susceptor 4 in MLE device a crystal growing chamber 2 of 1, the crystal growth chamber 2 in a ^10-8 by the vacuum evacuation system 7 via a gate valve 6
Evacuate to a pressure of about ^-10 Torr. Next, the infrared lamp 8 is turned on to heat the crystal substrate 3 to a predetermined temperature and to maintain the crystal substrate 3 at a constant temperature, for example, in the range of 250 to 500 ° C. Subsequently, each source gas, that is, a compound gas containing gallium (Ga), aluminum (Al), and arsenic (As) is supplied to a predetermined amount by the action of the flow rate adjusting mechanisms 11a, 12a, and 13a controlled by the gas introduction mode control system 14. The liquid flows through the nozzles 11, 12, and 13 at a flow rate. In the case of the embodiment shown in FIG. 4, gas is ejected from the gas ejection port (flat structure shown in FIG. 6) provided at the tip of the nozzle onto the crystal substrate 3. At that time, for example, gallium (Ga) triethyl gallium (TEG) as the compound gas containing, aluminum (Al) of triisobutylaluminum as the compound gas containing (TIBA), arsine as a compound gas containing arsenic (As) (AsH ₃₎ use. Here, the gas control mode controlled by the gas introduction mode control system 14 is, as shown in FIG. 2, the introduction waiting time t ₀ and the introduction time t _{1 of} the compound gas containing Al, and the introduction waiting time of the compound gas containing Ga. The time t ₂ and the introduction time t ₃ , and the introduction waiting time t ₄ and the introduction time t ₅ of the compound gas containing As are set to be the time t ₆ required for one cycle for introducing a series of source gases. In this gas introduction mode, a single-crystal thin film of Al _x Ga _{1 -x} As of several angstroms grows.

In the gas introduction mode, Al
Gas introduction pressure of the compound gas containing is 10 ^-6 to 10 ^-4 Tor
The gas introduction pressure of the compound gas containing r and Ga is 10 ^-6 to 1
The gas introduction pressure of the compound gas containing 0 ^-4 Torr and As is 10
^-5 to 10 ^-3 Torr, t ₀ = 0 to 5 seconds, t ₁ = 0 to 6
Seconds, t ₂ = 0 to 5 seconds, t ₃ = 1 to 6 seconds, t ₄ = 0 to 5
Seconds, t ₅ = 5-20 seconds, t ₆ = 6-47 seconds. Thus, the film thickness of the crystal growth of Al _x Ga _{1 -x} As obtained by one cycle of this gas introduction mode is 1
The range is from 10 to 10 °. Therefore, the value of one molecular layer is (10
Since it is about 2.8 ° on the (0) plane and about 3.3 ° on the (111) plane, by appropriately selecting the gas introduction pressure and introduction time of each raw material gas, one molecule of gas can be obtained by one cycle of gas introduction. Crystal growth of the layer is easily achieved. Also, Al
Similarly, the Al composition x of _x Ga _1-x As can be arbitrarily selected in the range of 0 <x <1 by appropriately selecting the gas introduction pressure and the introduction time of each source gas.

FIG. 7 shows an example of the structure of the crystal substrate 3 used for evaluating the in-plane distribution of the film thickness of crystal growth in the MLE method according to the present invention.
On the surface of a GaAs crystal substrate 31 having a size of mm × 15 mm,
SiH ₄ and NH ₃ using plasma CVD
_{A 3} N ₄ film 32 is formed, and has a width of 200 μm and a thickness of 1000 to 1000 μm.
The square GaAs crystal substrate surface 33 defined by the Si ₃ N ₄ film 32 is denoted by A to L in the vertical direction and 1 to 11 in the horizontal direction. Attach. This crystal substrate 3
At a substrate temperature of 380 ° C., an introduction pressure of TEG and AsH ₃ of 3 × 10 ⁻⁶ Torr and 2 × 10 ⁻⁴ Torr, and a gas introduction mode of (10 ″, 2 ″, 2 ″, 2 ″), That is, the AsH ₃ introduction time is 10 seconds, the AsH ₃ exhaust time is 2 seconds,
Assuming that the introduction time is 2 seconds and the TEG exhaust time is 2 seconds, FIG.
The raw material gas was introduced at 1200 cycles by the nozzle shown in FIG. 1, and the film thickness of the crystal growth was measured by a contact type step meter. As a result, the film thickness distribution of the crystal growth as shown in FIG. 8 was obtained. As a result, it was found that a thickness distribution of crystal growth within ± 2% can be achieved on a substrate having a size of 15 mm × 15 mm.

FIGS. 8 to 11 show the MLE apparatus 1 described above.
In the above, uneven portions 3a, 3b, 3c having different shapes by, for example, wet etching or dry etching, respectively.
Is formed on the crystal substrate 3 using the crystal substrate 3 on which
FIG. 8 shows an example in which molecular layer epitaxy of _x Ga _{1 -x} As 3 ′ is performed. In each case, almost the same crystal growth film thickness is obtained in the plane part and the side part, and as shown in FIG. It has been found that a uniform molecular layer can be formed even on the side part facing downward.

Next, FIG. 12 shows M for implementing the present invention.
This shows another example of the LE device, and this MLE device 41
Uses nozzles 42, 43, and 44 in which the nozzles of the gas introduction unit 5 are configured as described below, and light L ₁ of the same or different wavelength is applied to these nozzles 42, 43, and 44 from above. , L ₂ , and L ₃ , except that the MLE apparatus 1 has the same configuration as the MLE apparatus 1 of FIG. 1, and its operation is substantially the same. Each nozzle 42, 43,
Reference numeral 44 denotes a similar configuration. Among them, the nozzle 42 will be described. The nozzle 42 is formed in a substantially disk shape by quartz, Pyrex glass, sapphire, or the like so as to transmit infrared light, visible light, and ultraviolet light. A plurality of pipe-shaped gas outlets 42a are provided on the lower surface thereof (FIG. 1).
3).

The effectiveness of photoexcitation of the source gas is such that, by irradiating the source gas with light energy, an active gas molecule or a radical state can be created. Therefore, the reaction which has been conventionally caused by the supply of heat energy proceeds even at a low temperature. As a result, low-temperature growth becomes possible, and redistribution of impurities is suppressed, and a semiconductor crystal with good crystallinity can be obtained. Further, when irradiating the source gas with light, the gas molecules can be efficiently excited by light since the source gas is irradiated with light in a region where the source gas is present at a high concentration, that is, before the gas outlet of the nozzle. This is based on the principle that since the light scattering cross section of gas molecules is small, light is efficiently absorbed at a high concentration of gas molecules and the gas molecules are excited. Further, the surface reaction on the crystal substrate can be photo-excited by the light passing through the transparent nozzle, which can also lower the crystal growth temperature.

Using this MLE device 41, Al _x Ga
_When performing _1-x As crystal growth, the nozzles 42, 4
The raw material gas passing through the inside of the nozzle 4
After being photo-excited by the light L ₁ , L ₂ , L ₃ of the same or different wavelength applied to the inside of 2, 43, 44, it is ejected from the pipe-shaped gas ejection port into the crystal growth chamber 2 and on the crystal substrate 3 Causes a crystal growth reaction. The photoexcitation of the source gas enables crystal growth at a lower temperature than in the case of the MLE apparatus 1 shown in FIG. 1 and a radical state of the source gas molecule which does not exist in nature is generated by the photoexcitation. It is possible to make use of the crystal growth. Although the radical state generally has a short life, the raw material gas molecules are brought into a radical state immediately before being ejected from the pipe-shaped gas jet port. 3 surface can be reached.

In the above description, the GaAs crystal
Al on the substrate_xGa_1-xWhen As crystal is grown
However, the present invention is not limited to this. For example, TMIn (T
Limethyl indium), TEIn (triethyl indium)
M), PH_Three(Phosphine) etc.
, GaP, InP, InAs, In_xGa_{1- x}
As, In_xGa_1-xP, InAs_xP_1-x, GaAs
_xP_1-x, In_xGa _1-xAs_yP_1-y, Al_xGa
_1-xFor molecular layer epitaxy of III-V compounds such as P
Also DEZn (diethyl zinc), DETe
(Diethyl tellurium), DESe (diethyl selenium), H_Two
Se (hydrogenated selenium), H_TwoS (hydrogen sulfide) used
ZnS, ZnTe, ZnSe, ZnSe_xTe_1-xEtc.
Applicable to molecular layer epitaxy of II-VI compounds
It is clear that a similar effect can be obtained.

In the above-described molecular layer epitaxy, for example, in the case of doping in a group III-V compound semiconductor, Si, a group II or a group VI element is used as a dopant, and these are used as Si ₂ H ₆ , DEZn, DETe. ,
If a compound gas such as DESe, H ₂ Se, or H ₂ S is introduced into the crystal growth chamber through the nozzle of the present invention, the uniformity of the in-plane distribution of the dopant is significantly improved. Become.

Further, SiCl ₄ , SiHCl ₃ ,
In Si molecular layer epitaxy in which Si compound gases such as SiH ₂ Cl ₂ , Sih ₃ Cl and SiH ₄ and gases such as H ₂ and HCl are alternately introduced to grow single crystal Si one by one. According to the crystal growth method of the present invention, the uniformity of the in-plane distribution of the film thickness of each molecular layer growth film is remarkably improved.

[0026]

As described above, according to the first aspect of the present invention, when irradiating the source gas with light, the light is irradiated in a region where the source gas exists at a high concentration, that is, in front of the gas outlet of the nozzle. Since irradiation is performed, gas molecules can be efficiently photoexcited. Further, since the nozzle is formed to be transparent, the surface reaction on the crystal substrate can be photo-excited by the light transmitted through the transparent nozzle, whereby the crystal growth temperature can be lowered. Further, since the gas outlet is formed in a flat shape, the raw material gas does not collide with the inner wall of the vacuum vessel, so that a high-purity crystal containing no impurities can be obtained. Further, even in the case of growing a ternary mixed crystal semiconductor by molecular layer epitaxy, for example, in the case of crystal growth of Al _x Ga _{1 -x} As, the uniformity of the in-plane distribution of the value of the Al composition x is significantly improved. Becomes Thus, according to the present invention, it is possible to control the thickness of the semiconductor crystal thin film on the order of single molecules, and the directivity does not appear. , Uniform crystal growth is possible.

According to the second aspect of the present invention, a disk-shaped nozzle made of a material that transmits light is used, and a predetermined wavelength is applied to the raw material gas in front of the pipe-shaped gas ejection port of the disk-shaped nozzle. Is irradiated, and the gas molecules of the source gas are turned into a radical state by photoexcitation, so that molecular layer epitaxy using the molecules in the radical state becomes possible, and crystal growth at a lower temperature becomes possible. Therefore, a semiconductor crystal having good crystallinity while suppressing redistribution of impurities can be obtained. Furthermore, by arranging the respective nozzles in different directions and ejecting each source gas from a plurality of directions toward the crystal substrate through the respective gas ejection ports, the source gas can be ejected by a plurality of gas jets. By being ejected toward the crystal substrate from a plurality of directions via the outlet and directly reaching the crystal substrate, a more uniform supply of the source gas can be performed than in the case where the source gas is introduced from one direction in the related art. Therefore, uniform step coverage can be easily obtained even on a large-area crystal substrate.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of one embodiment of an MLE apparatus for carrying out the present invention.

FIG. 2 is a time chart showing an example of an introduction mode of the MLE device of FIG. 1;

FIG. 3 is a perspective view showing an example of a nozzle used in a conventional MLE device.

FIG. 4 is a perspective view showing an example of forming a nozzle used in the MLE apparatus of FIG. 1;

FIG. 5 is a perspective view showing another example of forming a nozzle used in the MLE apparatus of FIG. 1;

FIG. 6 is a perspective view showing a distal end portion of a pipe-shaped gas outlet of the nozzle of FIGS. 4 and 5;

FIGS. 7A and 7B show an example of the structure of a crystal substrate used for evaluating the in-plane distribution of the film thickness of crystal growth, wherein FIG. 7A is a plan view and FIG.

8 is a three-dimensional graph showing a film thickness distribution of a crystal growth film when crystal growth is performed using the crystal substrate of FIG.

9 is a horizontal graph showing the film thickness distribution of FIG.

FIG. 10 is a vertical graph showing the film thickness distribution of FIG. 8;

FIG. 11 is a cross-sectional view of a crystal substrate having a crystal substrate having a concave-convex portion, where the crystal is grown by the MLE apparatus of FIG. 1;

FIG. 12 is a schematic view of another embodiment of the MLE apparatus for carrying out the present invention.

13 shows an example of forming a nozzle used in the MLE apparatus of FIG. 12, wherein FIG. 13 (A) is a sectional view and FIG. 13 (B) is a bottom view.

[Explanation of symbols]

1,41 MLE apparatus 2 crystal growth chamber 3 crystal substrate 3 ′ crystal growth film 3a, 3b, 3c uneven part 4 quartz susceptor 5 gas introduction part 6 gate valve 7 vacuum exhaust system 8 infrared lamp 9 lamp chamber 11, 12, 13, 42, 43, 44 Nozzle 11a, 12a, 13a Flow rate adjusting mechanism 11b, 12b, 13b Valve 11c, 11d, 11e, 11f, 42a Pipe-shaped gas ejection port 11g Gas introduction port 11h Annular passage 11i Pipe section 14 Gas introduction mode control system 31 GaAs crystal substrate 32 Si ₃ N ₄ film 33 GaAs crystal substrate surface L ₁ , L ₂ , L ₃ irradiation light

Claims (7)

[Claims] 1. A gas supply nozzle, which is provided outside a growth chamber, is provided with a gas introduction nozzle from each source gas source of a plurality of types of source gases to a vicinity of a crystal substrate installed in a vacuum-evacuated growth chamber. In an apparatus in which each source gas is alternately ejected in a pulsed manner from each gas ejection port of the nozzle to epitaxially grow a semiconductor crystal on a monocrystalline layer on the crystal substrate, a plurality of gas ejection ports are provided from a gas introduction port of the nozzle. And the nozzles are formed transparent, and the tips of a plurality of gas ejection ports are formed in a flat shape, and at least one type of source gas is ejected from the gas ejection ports. Irradiating the transparent nozzle with light having a predetermined wavelength to excite the source gas. Shall growth apparatus. 2. A gas introduction nozzle is provided from each source gas source of a plurality of types of source gases provided outside the growth chamber to the vicinity of the crystal substrate installed in the evacuated growth chamber. An apparatus in which each source gas is alternately ejected in a pulsed manner from each gas ejection port of the nozzle to epitaxially grow a semiconductor crystal on the crystal substrate one by one monolayer, wherein a disk made of a material transmitting light through the nozzle is provided. A plurality of pipe-shaped gas ejection ports are provided on the lower surface of the disk-shaped nozzle, and light of a predetermined wavelength is emitted to the nozzle before at least one kind of source gas is ejected from the pipe-shaped gas ejection port. An apparatus for epitaxially growing a semiconductor crystal, wherein the source gas is photoexcited by irradiation. 3. The apparatus for epitaxially growing a semiconductor crystal according to claim 1, wherein a portion of the nozzle including a plurality of pipe-shaped gas outlets is heated to a predetermined temperature. 4. The method according to claim 1, wherein the plurality of nozzles are arranged in different directions, so that each source gas is ejected from a plurality of directions toward the crystal substrate through each gas ejection port. An apparatus for epitaxially growing a semiconductor crystal according to claim 1. 5. The method according to claim 1, wherein the at least one source gas is II
3. The apparatus for epitaxially growing a semiconductor crystal according to claim 1, wherein the gas contains a group I element and a gas containing a group V element. 6. The method according to claim 1, wherein the at least one source gas is II
The apparatus for epitaxially growing a semiconductor crystal according to claim 1, wherein the apparatus is a gas containing a group VI element and a gas containing a group VI element. 7. The method according to claim 1, wherein the at least one source gas is an IV gas.
The apparatus for epitaxially growing a semiconductor crystal according to claim 1, wherein the apparatus is a gas containing a group element.