JP7123348B2 - Organometallic Molecular Beam Epitaxy Method and Apparatus - Google Patents

Description

The present invention relates to molecular beam epitaxy, and more particularly to a method and apparatus for molecular beam epitaxy using organometallics as raw materials for molecular beams.

Nitrides containing transition metals are a group of substances that exhibit various practically useful physical properties such as metals and superconductivity, but compared to other inorganic substances such as oxides, they are difficult to synthesize. Substance development is slow. Moreover, although there is no intention to limit the present invention to this, in particular, the synthesis and material development of multi-component transition metal nitrides containing two or more kinds of metal elements are significantly behind.

The thin film technique is one of the powerful techniques for synthesizing nitrides. In fact, gallium nitride and its related nitrides, which are wide-gap semiconductors that have been widely put into practical use, were first synthesized by a thin-film technique that began in the latter half of the 1980s, and single-crystal wafers were finally realized in the 2000s. Among various thin film fabrication methods, molecular beam epitaxy, which can control thin film growth at the atomic layer level by individually supplying the elements constituting the thin film, is one of the methods that can obtain high quality thin films. In the thin film growth of transition metal nitrides, which exhibit various physical properties derived from electrons, the supply of transition metal raw materials with high melting points and low vapor pressures always poses a problem of unstable supply rates, making it difficult to prepare high-quality samples. (Non-Patent Document 1). In particular, in the synthesis of multicomponent transition metal nitrides containing two or more kinds of metals, it has a serious effect on the control of the composition ratio of thin film samples.

When a transition metal nitride thin film is produced by the molecular beam epitaxy (MBE) method, the raw material of the transition metal is supplied by electron beam evaporation or an effusion cell, and the transition metal, which is the raw material, is It is common to heat and evaporate the solid raw material of In this method, there is a limit to the upper limit of the raw material supply rate of the low vapor pressure transition metal, and the change in the supply rate over time is large enough to significantly affect the thin film growth. For example, in Patent Document 1, a transition metal (specifically, Ti) is heated by an electron beam from an electron gun to generate a molecular beam of the transition metal, and this is combined with atomic nitrogen generated by plasma generation. In forming a transition metal nitride thin film on a substrate by reaction, if open-loop control is performed without monitoring the amount of molecular beams supplied, the composition ratio of the transition element nitrides produced varies, resulting in It is explained that the thin films produced by may not have the desired properties.

For this reason, in previous research, in order to control the supply rate of the transition metal, the evaporation amount of the transition metal is detected by an electron impact emission spectrometer (EIES), and is constantly fed back to the heating temperature of the electron beam vapor deposition apparatus and the effusion cell. A system has been developed (Patent Document 1, Non-Patent Document 2). However, in this system, it is necessary to install the EIES in the MBE device, which inevitably increases the size of the device. In addition, since the EIES is a very expensive device, situations and objects in which it can be used are limited. Such problems are not limited to transition metals, but are the same for typical metals. is desired.

An object of the present invention is to stably supply a metal raw material such as a transition metal and to change the supply rate over a wide range, thereby achieving a transition metal without using a large and expensive apparatus. It is an object of the present invention to provide an MBE method and apparatus that enable formation of high-quality thin films of metal compounds such as metal nitrides.

According to one aspect of the present invention, a molecular beam epitaxy method is provided that provides an organometallic as a source of metal for molecular beam epitaxy.
Here, nitrides of said metals may be synthesized.
Also, atomic nitrogen may be supplied at the same time as the organic metal.
Alternatively, the organic metal, which is liquid or gaseous at room temperature, may be vaporized before being supplied.
The metal is selected from the group consisting of Ti, Mg, Al, V, Cr, Zn, Ga, Y, Zr, Nb, Mo, Ru, Cd, Sn, Hf, Ta, W, Ir, La, and Er. may be
Also, the organometallic may contain nitrogen.
In addition, the organic metal is Tetrakis dimethylamino titanium, Tetrakis diethylamino titanium, Tetrakis ethylmethylamino titanium, Bis(ethylcyclopentadienyl)magnesium, Bis(n-propylcyclopentadienyl)magnesium, Tri-i-butylaluminum, Triethylaluminum, Trimethylaluminum, Tetrakis(diethylamino)vanadium (IV ), Bis(ethylbenzene)chromium, Bis(i-propylcyclopentadienyl)chromium, Diethylzinc, Dimethylzinc, Triethylgallium, Tris(butylcyclopentadienyl)yttrium, Tetrakis(diethylamino)zirconium, Tris(ethylmethylamido)(tert-butylimido)niobium(V), Tris( diethylamido)(tert-butylimido)niobium(V), Bis(t-butylimido)bis(dimethylamino)molybdenum(VI), Bis(ethylcyclopentadienyl)ruthenium(II), Dimethylcadmium, Tetramethyltin, Tetraethyltin, Tetrakis(diethylamino)hafnium, Tetrakis( ethylmethylamino)hafnium, (t-Butylimido)tris(diethylamino)tantalum(V), Bis(t-butylimido)bis(dimethylamido) tungsten(VI), 1-Ethylcyclopentadienyl-1,3-cyclohexadieneiridium(I), Tris(i- propylcyclopentadienyl)lanthanum, and Tris(n-butylcyclopentadienyl)erbium.
Also, a raw material of a metal different from the metal may be supplied at the same time as the organic metal.
According to another aspect of the present invention, there is provided a molecular beam epitaxy apparatus for forming a film of a metal compound on a substrate by molecular beam epitaxy, comprising: a vacuum chamber in which the film is formed; and a gas source cell for supplying the metal-organic gas supplied from the metal-organic supply unit to the substrate placed in the vacuum chamber. Given.
Here, a substrate heating mechanism for heating the substrate may be provided.
Also, the compound of the metal may be a nitride of the metal.
Further, nitrogen in an atomic state may be supplied to the substrate simultaneously with the supply of the organic metal by the gas source cell.
Also, the distance between the substrate placed in the vacuum chamber and the gas source cell may be changed.
Further, the organic metal and the substance other than the organic metal are selectively supplied from the gas source cell to the substrate as raw materials for molecular beam epitaxy, and the raw materials are hardly adsorbed to the substrate. , the distance between the substrate and the gas source cell may be set to be small.
The metal is selected from the group consisting of Ti, Mg, Al, V, Cr, Zn, Ga, Y, Zr, Nb, Mo, Ru, Cd, Sn, Hf, Ta, W, Ir, La, and Er. may be
In addition, the organic metal includes Tetrakis dimethylamino titanium, Tetrakisdiethylaminotitanium, Tetrakisethylmethylaminotitanium, Bis (ethylcyclopentadienyl) magnesium, Bis (n-propylcyclopentadienyl) magnesium, Tri-i-butylaluminum, Triethylaluminum, Trimethylaluminum, Tetrakis (diethylamino) vanadium (IV), Bis ( ethylbenzene)chromium, Bis(i-propylcyclopentadienyl)chromium, Diethylzinc, Dimethylzinc, Triethylgallium, Tris(butylcyclopentadienyl)yttrium, Tetrakis(diethylamino)zirconium, Tris(ethylmethylamido)(tert-butylimido)niobium(V), Tris(diethylamido)(tert -butylimido)niobium(V), Bis(t-butylimido)bis(dimethylamino)molybdenum(VI), Bis(ethylcyclopentadienyl)ruthenium(II), Dimethylcadmium, Tetramethyltin, Tetraethyltin, Tetrakis(diethylamino)hafnium, Tetrakis(ethylmethylamino)hafnium, (t-Butylimido)tris(diethylamino)tantalum(V), Bis(t-butylimido)bis(dimethylamido)tungsten(VI), 1-Ethylcyclopentadienyl-1,3-cyclohexadieneiridium(I), Tris(i-propylcyclopentadienyl)lanthanum, and Tris(n-butylcyclopentadienyl)erbium.
According to still another aspect of the present invention, there is provided the molecular beam epitaxy apparatus according to any one of the above, having a mechanism for simultaneously supplying a raw material of a metal different from the metal to the substrate and the organic metal.

According to the present invention, in growing a transition metal nitride thin film using the MBE method, the instability caused by the use of a substance with a high melting point and a low vapor pressure as a raw material of the transition metal, and The raw material supply problem of slow supply speed is improved.

1 is a conceptual diagram of an organometallic MBE apparatus equipped with an organometallic raw material supply system; FIG. 4 is a graph comparing the vapor pressures of a solid material conventionally used as a metal material in a thin film produced by the MBE method and an organic transition metal that is in a liquid state at room temperature. Also, as reference information, typical examples of inorganic compounds of these metals are shown in the graph for TiO and Ti ₃ O ₅ for which the relationship between temperature and vapor pressure has been reported. Reflection high-energy electron diffraction image of a titanium nitride thin film taken during thin film fabrication with an organometallic MBE apparatus according to an embodiment of the present invention. FIG. 4 is an X-ray diffraction pattern of a titanium nitride thin film produced with an organometallic MBE apparatus according to one embodiment of the present invention; FIG.

As a result of research by the inventors of the present application, the variation in the quality of the transition metal nitride film described above is due to the fact that many transition metals have high melting points and low vapor pressures (for example, metal Ti has a melting point of 1668° C.), it was found that the evaporation of many transition metals is unstable. Moreover, since it has a high melting point and a low vapor pressure, the supply rate of the transition metal to the film-forming target is also low. The inventors of the present application have found that many of the organic compounds of transition metals (organotransition metals) are liquids, and such liquids have much lower melting points than their solid counterparts, such as the corresponding transition metals, as shown in FIG. , and the vapor pressure is much higher. Based on this knowledge, the inventors of the present application have proposed a transition metal raw material supply method that enables simple and highly accurate supply rate control and a wide range of raw material supply speed. However, we have invented an organometallic MBE process using organometallic materials.

According to one embodiment of the present invention, an organic metal containing a metal such as a transition metal, which is liquid at normal temperature and normal pressure and has a high vapor pressure, is used as the raw material. In order to synthesize a transition metal nitride, this organometallic raw material is preferably an organometallic molecule that does not contain oxygen, which easily forms a chemical bond with a metal element, in the molecule, and a nitrogen atom is coordinated around the transition metal ion. Organometallic molecules are preferred. Of course, it goes without saying that even organometallic compounds that do not contain nitrogen can form good-quality metal nitride films by appropriately controlling the reaction conditions.

Using the conceptual diagram of the MBE apparatus capable of performing MBE using an organometallic raw material shown in FIG. The raw material bottle 12 is connected to a specially developed vacuum gas line shown in the lower right region of FIG. A heater (not shown) is attached to the dedicated vacuum gas line and the organometallic raw material bottle 12 to perform heating for precisely controlling the amount of evaporation of the organometallic raw material. Furthermore, a flow control valve 11 and a vacuum gauge (flow meter) 10 for controlling the flow rate of the vaporized organometallic gas with high accuracy are attached to this dedicated vacuum gas line. The vaporized organometallic raw material passes through this dedicated vacuum gas line, passes through a gas source cell 8 having a novel structure, and is supplied into a vacuum chamber (MBE body growth chamber 1) for forming a thin film.

The gas source cell 8 is equipped with a uniaxial linear movement mechanism (Z stage) that can change the distance between the substrate 4 on which a thin film is formed and grown on its surface and the gas source cell 8. It is possible to control the adsorption amount of organometallic raw material molecules. The reason why it is necessary to change the distance between the two is that when performing MBE, the easiness of adsorption of the raw material to the substrate surface differs depending on the raw material, and the organic metal used in the present invention is the raw material that has been used conventionally. This is because the conventional MBE apparatus using a gas source cell in which the distance between the two is fixed is not compatible with the organometallic raw material used in the present invention. In the apparatus for performing MBE based on the present invention, it is usually necessary to be able to perform MBE using conventional raw materials as well. It is desirable to have this distance variable so that it can be set to the desired value to suit the distance. Specifically, the distance between the gas source cell 8 and the substrate 4 is shortened when supplying organometallic raw materials that are less likely to be adsorbed than conventional raw materials.

To further explain this distance, in order to adsorb molecules that are difficult to adsorb, it is necessary to bring the raw material supply source closer or increase the amount of raw material supplied in order to increase the adsorption probability of the molecules. If the amount of raw material supplied increases, the pressure rises (the degree of vacuum decreases), which affects the use of reflection high-energy electron diffraction (RHEED). The problem arises that a vacuum pump is required. On the other hand, since the amount of raw material supplied is inversely proportional to the distance between the raw material supply source and the substrate, it is an effective technique to bring the raw material supply source closer to the substrate. However, considering that the present invention is applied to a conventional MBE apparatus to switch between a conventional raw material and an organometallic raw material that is less likely to be adsorbed than such a raw material, in many apparatuses, the raw material supply Extensive modification of the equipment is required to install a mechanism for varying the distance between the source and the substrate. Of course, even if it is intended to use the existing MBE apparatus as an apparatus exclusively for organometallic raw materials, the above distance is too large to use organometallic raw materials, so it is realistic to use the existing apparatus as it is for the present invention. is difficult to Therefore, the apparatus of the present invention preferably has a uniaxial linear movement mechanism (Z stage) capable of varying the distance between the gas source cell and the substrate. This uniaxial linear movement mechanism (Z stage) moves, for example, the molecular beam outlet of the gas source cell back and forth along its blowing direction. The distance between the molecular beam outlet and the substrate is appropriately adjusted according to the types of molecules to be emitted and other parameters.

In performing MBE, the substrate 4 is heated by the substrate heating mechanism 2 via the substrate holder 3 to an appropriate temperature determined by the particular organometallic raw material used and other conditions.

This MBE apparatus is provided with an atomic nitrogen supply device (RF plasma source), which supplies atomic nitrogen generated by converting nitrogen gas into plasma into the MBE body growth chamber 1 . The organometallic raw material adsorbed on the substrate 4 is decomposed on the heated surface of the substrate 4 and reacts with the supplied atomic nitrogen to form a transition metal nitride thin film there.

In the structure shown in FIG. 1, only transition metals (organic metals) and nitrogen are supplied as raw materials for MBE, and a thin film of transition metal nitride is formed on the substrate. However, the present invention is not limited to this, and multi-component transition metal nitrides (e.g., two or more different typical compounds with various composition ratios such as AMN ₂ , A ₂ MN ₂ , AM ₂ N ₂ , etc.) Nitrides containing elemental metals or transition metals, where M and A are both transition metals or main group metals, can also be deposited. In order to realize this, a beam of A-site atoms or a compound thereof is supplied from a raw material supply cell (not shown) separately provided in the molecular beam epitaxy main body growth chamber 1, and an organometallic raw material for the M-site is supplied. At the same time, by supplying to the surface of the substrate 4 and reacting there, a desired multi-component transition metal nitride thin film can be formed there.

FIG. 1 also shows an electron gun 5 for reflection high-energy electron diffraction and a screen 6 for reflection high-energy electron diffraction. This makes it possible to take a reflected high-energy electron beam diffraction image of the thin film produced by this MBE apparatus and evaluate the flatness, crystallinity, etc. of the thin film surface. Also, it should be noted that any other device that can be provided in a typical MBE device can be suitably selected and employed as long as it is not detrimental to the present invention.

Although the present invention can be applied to many transition metals, titanium (Ti) will be described below as a representative example. It is clear that the use of Ti as an example is not without loss of generality.

Here are non-limiting examples of substances that can be used as organometallic sources in the present invention:
・Tetrakis dimethylamino titanium (TDMAT, Ti[N( _CH3 ) ₂ ] ₄ )

・Tetrakisdiethylaminotitanium (TDEAT, Ti[N _{( C2H5} ) ₂ ] ₄ )

・Tetrakisethylmethylaminotitanium (TEMAT, Ti[N _{( C2H5} ) _CH3 ] ₄ )

The physical properties and the like of the three types of organic metals exemplified above are shown in the table below.

Organic metal raw materials other than Ti are, of course, not intended to be limited to these, nor do they not exist, but are listed and exemplified below. In selecting organic compounds to be taken up as examples, those that are commercially available and that can be used in the MBE apparatus of the present invention actually made by the inventors of the present application are candidates that are liquid at around room temperature (25°C). , selected from among them. Therefore, solid (powder/crystal) organometallic raw materials were excluded. Of course, it is possible to use organic metals such as solids by appropriately modifying the structure and control of the organic metal supply system, such as supplying to the organic metal gas source cell after heating and vaporizing it. Needless to say. Organic compounds of metals other than transition metals, such as Mg and Al, are also included in the list of organometallic compounds exemplified below. Note that there are raw materials such as Zr (zirconium), Ta (tantalum), Nb (niobium), Hf (hafnium), and W (tungsten) that cannot be supplied by ordinary MBE.

・Examples of organometallic compounds of Mg (magnesium):
( ₁ ) Bis ₍ ethylcyclopentadienyl)magnesium, _{( C2H5C5H4} ) _2Mg
( ₂ ) Bis(n _- propylcyclopentadienyl)magnesium, _{( C3H7C5H4} ) _2Mg
・Examples of organometallic compounds of Al (aluminum):
( ₃ ) Tri-i-butylaluminum, _{( C4H9} )3Al
( ₄ ) Triethylaluminum, _{( C2H5} )3Al
( ₅ ) Trimethylaluminum, ( _CH3 )3Al
・Examples of organometallic compounds of V (vanadium):
(6) Tetrakis(diethylamino)vanadium( _IV ), TDEAV, V[N( _CH2CH3 ) ₂ ] ₄
・Examples of organometallic compounds of Cr (chromium):
(7) Bis(ethylbenzene)chromium, [(C ₂ H ₅ ) _x C ₆ H _6-x ] ₂ Cr
(8) Bis(i _- propylcyclopentadienyl)chromium, [ _{( C3H7} ) _C5H4 ] _2Cr
・Examples of organometallic compounds of Zn (zinc):
(9) _Diethylzinc , Zn( _C2H5 ) ₂
(10) Dimethylzinc, Zn( _CH3 ) ₂
・An example of an organometallic compound of Ga (gallium):
(11) Triethylgallium, _{( C2H5} ) _3Ga
・Examples of organometallic compounds of Y (yttrium):
( ₁₂ ) Tris ₍ butylcyclopentadienyl)yttrium _{, ( C4H9C5H4} )3Y
- Examples of organometallic compounds of Zr (zirconium):
(13) Tetrakis(diethylamino)zirconium, Zr[N _{( CH2CH3} ) ₂ ] ₄
・Examples of organometallic compounds of Nb (niobium):
(14) Tris(ethylmethylamido)(tert-butylimido)niobium( _V ), TBTEMN, [( _C2H5 )( _CH3 )N] _3Nb =N[C( _CH3 ) ₃ ]
(15) Tris(diethylamido)(tert-butylimido)niobium( _V ), TBTDEN, [(C2H5)2N] _{3Nb =} N[C _{( CH3} ) ₃ ]
・Examples of organometallic compounds of Mo (molybdenum):
(16) Bis(t-butylimido)bis ₍ dimethylamino)molybdenum ₍ VI), _C12H30MoN4
- Examples of organometallic compounds of Ru (ruthenium):
(17) Bis(ethylcyclopentadienyl)ruthenium( _II ), [ _{( CH3CH2} ) _C5H4 ] _2Ru
・Examples of organometallic compounds of Cd (cadmium):
(18) Dimethylcadmium, ( _CH3 ) _2Cd
・Examples of organic compounds of Sn (tin):
(19) Tetramethyltin, ( _CH3 ) _4Sn
( ₂₀ ) Tetraethyltin, ( _CH3CH2 ) _4Sn
・Examples of organometallic compounds of Hf (hafnium):
(21) Tetrakis(diethylamino)hafnium, Hf[N _{( CH2CH3} ) ₂ ] ₄
(22) Tetrakis(ethylmethylamino)hafnium, Hf[N( _CH3 ) _{( CH2CH3} )] ₄
・An example of an organometallic compound of Ta (tantalum):
(23) (t- _Butylimido )tris(diethylamino)tantalum ₍ V), _C16H39N4Ta
・Examples of organometallic compounds of W (tungsten):
(24) Bis(t-butylimido)bis ₍ dimethylamido) tungsten ₍ VI), _C12H30N4W
Examples of organometallic compounds of Ir (iridium):
(25) 1-Ethylcyclopentadienyl-1,3-cyclohexadieneiridium ₍ I), _C13H17Ir
・Examples of organometallic compounds of La (lanthanum):
(26) Tris(i- _{propylcyclopentadienyl} )lanthanum _{, ( C3H7C5H4} ) _3La
・An example of an organometallic compound of Er (erbium):
(27) Tris(n _- butylcyclopentadienyl)erbium _{, ( C4H9C5H4} ) _3Er

<Example: Preparation of titanium nitride (TiN) epitaxial thin film using TDMAT as organometallic raw material>
High-quality titanium nitride (TiN) epitaxial thin films were fabricated using MBE equipped with an organometallic feed system, an example of which is shown in FIG. TDMAT was used as an organometallic raw material for titanium (Ti), which is a transition metal. Since the molecular structure of this TDMAT is a structure in which four nitrogen atoms are coordinated around Ti, it is expected that the contained nitrogen atoms contribute to the growth of the titanium nitride thin film.

As shown in FIG. 1, a TDMAT raw material bottle 12 connected to an organometallic supply system was heated and vaporized, and TDMAT was supplied through a heated gas line into a vacuum chamber 1 where a thin film was grown. As shown in FIG. 2, the various organic metals such as TDMAT used here, which are liquid at room temperature, can be used as solid state metal raw materials such as Sr, Sn, Si, and Ti, which have been conventionally used or have been considered for use. In comparison, it vaporizes at a very low temperature and has a very high vapor pressure. Further, solid organic metal raw materials have a lower melting point and a higher vapor pressure than solid raw materials such as Sr, Sn, Si, and Ti, although not as much as liquid organic metal raw materials. Therefore, not only liquid organic metals but also organic metals that are solid at room temperature can be used as the metal material of the present invention. This makes organometallics very suitable as metal sources for use in MBE for the deposition of metal compounds. This gas line is equipped with a vacuum gauge 10 and a flow control valve 11 that can measure the pressure of the TDMAT gas with high precision and adjust the flow rate. A molecular beam of TDAMT was supplied through a gas source cell 8 provided in the vacuum chamber 1 toward a substrate 4 installed in the vacuum chamber 1 and on which a thin film was to be formed. The gas source cell 8 is equipped with a uniaxial linear movement mechanism (Z stage) that can move the outlet back and forth along the molecular beam outlet direction, and adjusts the distance between the beam outlet and the substrate 4 according to the required thin film growth rate. can be set by A strontium titanate single crystal substrate (SrTiO ₃ (100)) was used as the substrate 4 and heated to 600° C. to 900° C. by the substrate heating mechanism 2 . Simultaneously with the supply of TDMAT, which is a Ti raw material, atomic nitrogen generated from a radio frequency (RF) plasma source 7 was also supplied as a nitrogen (N) raw material. Here, as described above, film formation was performed by optimizing the distance between the beam outlet and the substrate 4 . Thus, a TiN epitaxial thin film was formed on the substrate 4 surface.

As shown in FIG. 3, high surface flatness, high crystallinity, and a streak reflection high-energy electron diffraction image, which means epitaxial growth, were obtained from the thin film being formed on the surface of the substrate 4 .

The X-ray diffraction pattern of the produced TiN epitaxial thin film was measured, and the pattern shown in FIG. 4 was obtained. In these X-ray diffraction patterns, only the diffraction peaks of the substrate SrTiO ₃ and TiN of the rocksalt type crystal structure were observed, indicating that a single-phase sample containing no heterogeneous phase was obtained. The peak intensity of the TiN thin film is very large, and even in the TiN (400) diffraction peak on the high angle side, a clear separation of the diffraction peaks due to the CuK 1 line and the CuK 2 line is confirmed, demonstrating high crystallinity. became. In addition, the lattice constant (0.4246 nm) of the prepared TiN thin film is almost the same as the bulk lattice constant (0.424173 nm, ICDD#00-038-1420), indicating that a stoichiometric thin film has been obtained. I found out.

As described above, according to the present invention, an epitaxial thin film of a transition metal nitride of very high quality can be easily produced without precisely observing and controlling the supply rate of the transition metal when performing MBE.

A molecular beam epitaxy method using an organic metal containing a transition metal as a raw material, and its apparatus enables highly accurate supply amount control of the transition metal raw material and a wider range without using an expensive spectroscopic device such as EIES. It became possible to change the raw material supply speed. INDUSTRIAL APPLICABILITY According to the present invention, it is possible to prepare high-quality samples of transition metal nitrides, especially multi-component transition metal nitrides, and it is expected to promote the development of new materials and functional development research.

1: Molecular Beam Epitaxy Body Growth Chamber 2: Substrate Heating Mechanism 3: Substrate Holder 4: Substrate 5: Electron Gun for Reflection High-energy Electron Diffraction 6: Screen for Reflection High-energy Electron Diffraction 7: Atomic Nitrogen Supply Device (RF Plasma Source )
8: Organometallic gas source cell 9: Organometallic raw material supply system 10: Vacuum gauge 11: Flow control valve 12: Organometallic raw material bottle

JP 2013-170098 A

Theis et al., J. Vac. Sci. Technol. A 14, 2677 (1996). Krockenberger et al., J. Appl. Phys. 112, 083920 (2012).

Claims (15)

In a molecular beam epitaxy method for supplying an organic metal as a metal source for molecular beam epitaxy,
selectively supplying the organic metal and a substance other than the organic metal to the substrate from a gas source cell as raw materials for molecular beam epitaxy;
A molecular beam epitaxy method in which the distance between the substrate and the gas source cell is reduced so that the raw material is less likely to be adsorbed to the substrate. 2. The method of molecular beam epitaxy according to claim 1, wherein a nitride of said metal is synthesized. 3. The molecular beam epitaxy method according to claim 2, wherein atomic nitrogen is supplied simultaneously with said organometallic. 4. The molecular beam epitaxy method according to any one of claims 1 to 3, wherein said organic metal which is liquid or gas at room temperature is vaporized before being supplied. Said metal is selected from the group consisting of Ti, Mg, Al, V, Cr, Zn, Ga, Y, Zr, Nb, Mo, Ru, Cd, Sn, Hf, Ta, W, Ir, La, Er The molecular beam epitaxy method according to any one of claims 1 to 4. 6. The molecular beam epitaxy method according to any one of claims 1 to 5, wherein said organic metal contains nitrogen. The organic metals include Tetrakis dimethylamino titanium, Tetrakisdiethylaminotitanium, Tetrakisethylmethylaminotitanium, Bis(ethylcyclopentadienyl)magnesium, Bis(n-propylcyclopentadienyl)magnesium, Tri-i-butylaluminum, Triethylaluminum, Trimethylaluminum, Tetrakis(diethylamino)vanadium(IV), Bis(ethylbenzene) chromium, Bis(i-propylcyclopentadienyl)chromium, Diethylzinc, Dimethylzinc, Triethylgallium, Tris(butylcyclopentadienyl)yttrium, Tetrakis(diethylamino)zirconium, Tris(ethylmethylamido)(tert-butylimido)niobium(V), Tris(diethylamido)(tert-butylimido )niobium(V), Bis(t-butylimido)bis(dimethylamino)molybdenum(VI), Bis(ethylcyclopentadienyl)ruthenium(II), Dimethylcadmium, Tetramethyltin, Tetraethyltin, Tetrakis(diethylamino)hafnium, Tetrakis(ethylmethylamino)hafnium, (t -Butylimido)tris(diethylamino)tantalum(V), Bis(t-butylimido)bis(dimethylamido)tungsten(VI), 1-Ethylcyclopentadienyl-1,3-cyclohexadieneiridium(I), Tris(i-propylcyclopentadienyl)lanthanum, and Tris 6. The molecular beam epitaxy method according to any one of claims 1 to 5, which is selected from the group consisting of (n-butylcyclopentadienyl)erbium. 8. The molecular beam epitaxy method according to claim 1, wherein a raw material of a metal different from said metal is supplied simultaneously with said organic metal. a vacuum chamber in which film formation takes place;
an organometallic supplier that supplies the vaporized organometallic;
a gas source cell for supplying the metal-organic gas supplied from the metal-organic supply unit to the substrate placed in the vacuum chamber, and forming a metal compound film on the substrate by molecular beam epitaxy. In line epitaxy equipment,
The distance between the substrate placed in the vacuum chamber and the gas source cell can be changed, and the organic metal and the substance other than the organic metal are used as raw materials for molecular beam epitaxy in the gas source cell. configured to selectively supply the substrate from
A molecular beam epitaxy apparatus that can be set so that the distance between the substrate and the gas source cell is reduced as the source material is less likely to be adsorbed to the substrate. 10. The molecular beam epitaxy apparatus according to claim 9, further comprising a substrate heating mechanism for heating said substrate. 11. The molecular beam epitaxy apparatus according to claim 9, wherein said metal compound is a nitride of said metal. 12. The molecular beam epitaxy apparatus according to any one of claims 9 to 11, wherein nitrogen in an atomic state is supplied to the substrate simultaneously with the supply of the organic metal by the gas source cell. Said metal is selected from the group consisting of Ti, Mg, Al, V, Cr, Zn, Ga, Y, Zr, Nb, Mo, Ru, Cd, Sn, Hf, Ta, W, Ir, La, Er , the molecular beam epitaxy apparatus according to claim 9-12. The organic metals include Tetrakis dimethylamino titanium, Tetrakisdiethylaminotitanium, Tetrakisethylmethylaminotitanium, Bis(ethylcyclopentadienyl)magnesium, Bis(n-propylcyclopentadienyl)magnesium, Tri-i-butylaluminum, Triethylaluminum, Trimethylaluminum, Tetrakis(diethylamino)vanadium(IV), Bis(ethylbenzene) chromium, Bis(i-propylcyclopentadienyl)chromium, Diethylzinc, Dimethylzinc, Triethylgallium, Tris(butylcyclopentadienyl)yttrium, Tetrakis(diethylamino)zirconium, Tris(ethylmethylamido)(tert-butylimido)niobium(V), Tris(diethylamido)(tert-butylimido )niobium(V), Bis(t-butylimido)bis(dimethylamino)molybdenum(VI), Bis(ethylcyclopentadienyl)ruthenium(II), Dimethylcadmium, Tetramethyltin, Tetraethyltin, Tetrakis(diethylamino)hafnium, Tetrakis(ethylmethylamino)hafnium, (t -Butylimido)tris(diethylamino)tantalum(V), Bis(t-butylimido)bis(dimethylamido)tungsten(VI), 1-Ethylcyclopentadienyl-1,3-cyclohexadieneiridium(I), Tris(i-propylcyclopentadienyl)lanthanum, and Tris 14. The molecular beam epitaxy apparatus according to any one of claims 9 to 13, which is selected from the group consisting of (n-butylcyclopentadienyl)erbium. 15. The molecular beam epitaxy apparatus according to any one of claims 9 to 14, further comprising a mechanism for supplying a raw material of a metal different from said metal to said substrate at the same time as said organic metal.

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