JP3503054B6 - Crystalline film manufacturing method and apparatus - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for epitaxially growing a crystalline film of the same or different material as a substrate crystal on a crystalline substrate, and more particularly to a method of manufacturing a silicon single crystal in a field of materials in the electronics field. A method for growing a crystalline film of a silicide material on a substrate.
[0002]
[Prior art]
In order to produce a high quality single crystal film of a semiconductor material, various film forming methods have been conventionally developed, including a molecular beam epitaxial film forming method, a sputter film forming method, and a CVD film forming method. Is widely known. Among them, the molecular beam epitaxial film forming method is a method of growing a film in an ultra-high vacuum atmosphere, and thus is a method generally accepted in the industry as a method capable of obtaining a very high quality film with few impurities. is there. The material field where the molecular beam epitaxial film formation method is most effective is to produce a high-quality epitaxial film of a III-V group compound semiconductor material such as gallium arsenide, which is generally difficult to produce a high-quality substrate bulk material. It is a scene.
[0003]
[Problems to be solved by the invention]
Beta iron silicide is an environmental semiconductor material in which one iron atom and two silicon atoms constitute a molecule. Numerous approaches have also been attempted to produce good quality films of beta iron silicide. Heretofore, attempts have been made to form a beta iron silicide film using a molecular beam epitaxial growth method widely used for producing a semiconductor epitaxial film. However, to date, attempts to grow a beta-iron silicide epitaxial film by simultaneously irradiating a silicon substrate kept at a high temperature with a silicon molecular beam and an iron molecular beam have shown that a polycrystalline structure has been removed except for an extremely thin film. And it is said that an accurate stoichiometric composition ratio cannot be realized. On the other hand, film formation using a silicon ion beam and an iron ion beam alternately in place of a molecular beam has also been attempted. The original purpose of an ion beam is to realize high-purity film formation by performing mass separation using a magnetic field and then selecting ion species after ionization. It is said that an epitaxial film grows. However, in this method, since the tendency that most of the molecular beam flux is lost at the stage of ion beam formation is inevitable, productivity is greatly impaired. The equipment also becomes large-scale, and practical application is difficult in terms of production cost.
[0004]
[Means for Solving the Problems]
In the present invention, by utilizing an ionized molecular (atomic) beam, it is possible to epitaxially grow a thin film such as a beta iron silicide material containing a high melting point material as a component, which has conventionally been difficult to produce an epitaxial thin film. Provide a membrane method.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic diagram of a film forming apparatus using a partially ionized beam 9 according to the present invention. In this example, a sample holder 2 for holding a substrate material 1 made of, for example, silicon single crystal heated to a temperature suitable for film growth, and a manipulator 3 for controlling the position and direction of the holder are shown. The partial ionization beam 9 made of, for example, iron is used to evaporate the raw material iron to emit an iron molecular beam, and to irradiate the electron beam with an electron shower to partially ionize the iron beam. Is supplied from a partial ionization beam source composed of the ionization mechanism 8 of FIG. The growth chamber 10 is typically evacuated to ultra-high vacuum by a vacuum pump system (not shown). In addition to the partially ionized beam source, the figure includes conventional neutral molecular beam sources 4 and 5. These evaporation sources supply, for example, a neutral molecular beam of silicon or a neutral molecular beam of antimony other than iron, and supply materials other than iron necessary for forming a beta iron silicide film.
[0006]
When performing film formation using this apparatus, three types of modes may be considered. First, it will be appreciated that if the ionization mechanism for the partially ionized beam is not activated, the cell will function as a conventional K-cell that supplies a conventional neutral beam. In that case, film formation by the conventional MBE technique can be performed. Next, when the ionization mechanism is operated, it is possible to realize multi-material deposition utilizing the partial ionization beam of the present invention in combination with the neutral molecular beam from the conventional K cell. It is possible to change the ionization efficiency by controlling the electron generation and thermionic acceleration voltage. As a result, the ratio between the ion flux and the neutral flux in the partial ionization beam can be changed, and it is possible to select an ionization ratio that can realize optimal film formation in accordance with the combination of materials. The combined use of an ionization beam is expected to realize the epitaxial growth of an epi-difficult material such as beta iron silicide, which could not be conventionally achieved by a neutral molecular beam.
[0007]
Further, a film forming technique utilizing the surfactant effect is known, but new film forming by applying the present apparatus to the technique is possible. As an example, a case in which a beta iron silicide film is formed using a surfactant effect will be described. In the apparatus of FIG. 1, an SbSi2 film can be grown by supplying a molecular beam of antimony to a silicon substrate from one of the conventional K cells. At this time, if an iron beam is supplied simultaneously as a partial ionization beam, antimony is replaced by iron by a surface reaction due to a surfactant effect, and FeSi2 is formed. The beta iron silicide film grows by maintaining the substrate temperature at this time at a beta phase formation temperature of about 950 ° C. or less. The substituted antimony evaporates by itself.
[0008]
FIG. 2 is a schematic diagram showing a configuration example of the partial ionization beam source in more detail. By irradiating a molecular beam from a conventional evaporation source (K cell) with an electron shower in the ionization mechanism, a part of the molecules (atoms) of the neutral molecular beam is ionized, thereby forming a partially ionized beam. Supplied. According to the present method, a simple ionization mechanism is added to the outlet of a normal evaporation source (K cell) without requiring a large-scale apparatus for ionizing all atoms and performing mass spectrometry. Since the apparatus can be constructed, the cost of the apparatus can be kept low, and the beam flux is not lost.
[0009]
FIG. 3 schematically shows an epitaxial film growth mechanism on the substrate surface. Regarding the difference in behavior on the substrate surface when neutral atoms and ions in the low energy region enter the substrate, it is conceivable that the energy of the flying particles is different. The kinetic energy of molecules or atoms in a molecular beam emitted from an evaporation source heated to a temperature of about 1000 ° C. is at most about 0.1 eV, whereas the acceleration voltage of a general ion beam is several eV. To about 1 keV, even at the lowest acceleration, the atoms carried by the ion beam reach the substrate surface with about one order of magnitude greater energy than thermal atoms. Therefore, it can be considered that the ionized molecules can easily move to the kink position, which is the growth front, while actively moving on the substrate surface, and the epitaxial film growth is promoted. It is expected that the probability of epitaxial film formation will be increased because the activated surface motion will increase the chances of crossing the reaction potential barrier to form beta iron silicide molecules. Other than speculation, due to the electromagnetic force effect of the charged charge accompanying ionization, ions move on the substrate surface, aggregate into kinks, bond with the substrate atoms and the partner atoms that constitute iron silicide molecules. , Etc. would be expected to be more activated than in the neutral case. The effect of such an ionized beam is expected even if all of the atomic flux is not ionized. As described with reference to FIG. 2, a simple structure in which a thermoelectron emission source is provided at the exit of the K cell, which is a general molecular beam source, ionizes some molecules (atoms) of the molecular beam evaporated from the K cell. By doing so, a partially ionized beam can be produced. By ionizing, it is possible to control the energy of ions by changing the ion acceleration voltage, and to accurately measure the number of ions by measuring the beam current. The deposition mode will change depending on the ion beam energy region. In the case of an ion beam of about 20 eV or less, which is the displacement energy of the substrate atoms, the ion beam is expected to be actively moved on the surface without repelling the substrate atoms. I can imagine. In the case of an ion beam having an energy larger than this, if it is several keV or more, it becomes a so-called ion implantation region, and the effect of embedding in the substrate will be remarkable. In these intermediate energy regions, implantation into a very shallow surface region and film deposition growth occur simultaneously, which may be effective when a barrier layer or the like exists on the very surface.
[0010]
Materials for which the present method is expected to be suitable include those which would have been difficult to form with conventional simple MBE. Among them, the present method will be effectively applied to a film containing silicon as a high melting point material, in particular, a silicide material in general. Although there are many types of silicide semiconductor materials, beta-iron silicide, calcium silicide, magnesium silicide, and manganese silicide, which are called environmental semiconductors, are promising when considering the abundance of resources and the effect on the human body.
[0011]
FIG. 4 shows another embodiment of the partial ionization beam source of the present invention. Here, a deflection electrode for applying an electrostatic deflection voltage to the beam emitted from the partial ionization beam source is added. Since this deflection electrode deflects only the ion beam included in the beam, by appropriately selecting the deflection voltage, only the ion beam reaches the substrate as shown in FIG. The substrate can not be reached. Of course, discarding the neutral beam in this way greatly reduces the beam flux, but it will be a method that can be used sufficiently when a low flux is sufficient, such as by introducing an impurity dopant for controlling the electric conduction type of the film. . The dopants in beta iron silicide would include cobalt and nickel in the n-type and manganese in the p-type.
[0012]
Until now, as a mechanism for supplying a partially ionized beam, a neutral molecular beam from a conventional evaporation source has been used, but a different mechanism is also possible. For example, a method of supplying an ionized beam using a laser ablation technique is possible. Alternatively, a beam from a conventional ion source could be used directly.
[0013]
Although the process of forming a compound film by combining a partially ionized beam with a conventional neutral molecular beam has been described herein, all beams can be partially ionized beams. In addition, although the present specification has described the deposition of a material containing two or more components, growing a single-element material using a partial ionization beam is also included in the scope of the present invention.
【The invention's effect】
In the present invention, by utilizing an ionized molecular (atomic) beam, it is possible to epitaxially grow a thin film such as a beta iron silicide material containing a high melting point material as a component, which has conventionally been difficult to produce an epitaxial thin film. Become.
[Brief description of the drawings]
FIG. 1 is a schematic view of a film forming apparatus incorporating a first preferred embodiment of a partial ionization beam source according to the present invention.
FIG. 2 is a schematic view of a partial ionization beam source according to the present invention.
FIG. 3 is a schematic diagram of a mechanism for growing an epitaxial film on a substrate.
FIG. 4 is a schematic diagram of another preferred embodiment of the partial ionization beam of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Substrate 2 Substrate holder 3 Manipulators 4 and 5 for substrates Neutral molecular beam source 6 Partial ionization beam source 8 Ionization mechanism 9 Partial ionization beam 10 Growth chamber

Claims (4)

A method for producing a crystalline film of the same or different material as the single crystal substrate material on a single crystal substrate material, comprising:
In a state where the single crystal substrate material is heated in a vacuum atmosphere to a temperature suitable for crystal growth of the material to be grown, a molecular or atomic beam flux emitted from at least one evaporation source is partially ionized. manner the ionized molecules or atoms beam-out guide to the substrate, and simultaneously added to the partially ionized molecules or atomic beam, guides the neutral molecules or atoms beams from one or more evaporation sources to the substrate,
A surface reaction to supply constituent elements of to be grown material by surfactant effect Accordingly, growing a crystalline material film to the substrate,
A method for producing a crystalline film. The partial ionization comprises ionizing a molecule or atom contained in the emitted molecule or atom beam by irradiating an electron beam to a molecule or atom beam flux emitted from an evaporation source. Item 4. The method for producing a crystalline film according to Item 1. A crystalline film manufacturing apparatus for growing a crystalline film of the same or different material as the single crystal substrate material on a single crystal substrate material,
Means for partially ionizing a molecular or atomic beam flux emitted from at least one evaporation source while heating the single crystal substrate material in a vacuum atmosphere to a temperature suitable for crystal growth of the material to be grown ;
Means for directing a neutral molecule or atom beam from one or more evaporation sources onto said substrate;
Wherein the partially ionized molecules or atoms beam pressurized forte, simultaneously directing the neutral molecule or atom beams onto said substrate, wherein supplying the constituent elements of the to be grown material by surface reaction with Surf Akutanto effects board crystalline film production apparatus which comprises growing a crystal of the material film onto. The partial ionization comprises ionizing a molecule or atom contained in the emitted molecule or atom beam by irradiating an electron beam to a molecule or atom beam flux emitted from an evaporation source. Item 4. A crystalline film production apparatus according to Item 3 .

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