JP3610372B2 - Film formation method and apparatus by negative ion irradiation and simultaneous vapor deposition - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention of this application relates to a film forming method and apparatus using negative ion irradiation and simultaneous vapor deposition. More specifically, the invention of this application relates to a novel film forming method capable of forming a fine particle dispersed film useful as a functional film such as a nonlinear optical material by a film forming method by dynamic mixing using negative ions, and therefore It is related with the apparatus of.
[0002]
[Prior art and its problems]
The dynamic mixing process that forms a film composed of multiple elements by simultaneously performing vacuum deposition and ion implantation is performed at the atomic level by ion irradiation, so that the substance that constitutes the vapor and the substance that constitutes the ion beam It is a film formation method which can form the film | membrane which consists of densely with arbitrary film thicknesses. In this method, it is possible to form a film at room temperature, which cannot normally be formed unless the temperature is high, and the temperature rise of the substrate surface can be controlled. It also has the feature that it can be prevented.
[0003]
However, in the conventional dynamic mixing process, in order to irradiate positive ions with low energy, when the base material is an insulator, the ion beam is caused by clone repulsion due to charging by positive charges accumulated on the base material surface. The beam travel direction is not constant, and the ion beam does not reach the substrate, so that continuous film formation is impossible, and the density of elements constituting the film is not possible. It was difficult to achieve a high density and uniformity.
[0004]
On the other hand, in the field of ion vapor deposition, attempts have been made to use negative ions in order to prevent the above-described charging, that is, charge-up associated with film formation on an insulating substrate.
[0005]
However, with regard to the use of negative ions so far, formation of a metal film by metal negative ions and formation of a reactive film using negative ions of gas elements such as oxygen and nitrogen have been reported. The fact is that little consideration has been given to the production of new membrane structures and new functional membranes.
[0006]
For this reason, for example, it has not been attempted to produce a new nonlinear optical material by utilizing the non-equilibrium of ion irradiation.
[0007]
Therefore, the invention of this application has been made in view of the circumstances as described above, and a new film structure or a new functional film can be arbitrarily selected by using an insulator substance as a film base material by dynamic mixing treatment with negative ions. It is an object of the present invention to provide a film forming method and an apparatus therefor that can be manufactured with a film thickness of 1 mm.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention of this application is as follows. First, in the vacuum vessel, ion irradiation from the ion source to the sample substrate surface and vapor deposition of the film base material on the sample substrate surface are performed simultaneously. A film forming method using dynamic mixing, in which ions irradiated from an ion source are negative ions of a non-metallic element that can be supersaturated in a metallic element or an insulator , and a film base material that is simultaneously deposited on a sample substrate providing There is an insulator material, the film forming method according to the negative ion irradiation simultaneous deposition particles of the metal element or the non-metallic element and forming a fine particle dispersed film, which is dispersed in the membrane substrate To do.
[0009]
The invention of this application relates to the above method, and secondly, the film substrate is one of SiO ₂ , Al ₂ O ₃ , MgO, MgO—Al ₂ O ₃ , LiNbO ₂ and BaF ₂ or Provided is a film forming method of two or more, and third, negative ions are Cu, Co, Ni, Zn, Mo, Pd, Ag, Cd, Hf, Ta, W, Re, Ir, Pt, Au , Hg, B, C, Si, P, Ge, As, Se, and Sb, and fourth, a film having a diameter of 1 to 20 nm. Fifth, a film forming method in which the fine particles are single crystals is provided.
[0010]
According to a sixth aspect of the present invention, there is provided any one of the above-described film forming methods for forming a nonlinear optical film.
[0011]
Further, according to the seventh aspect of the present invention, as a device for any one of the above methods, a non-metallic element that can be supersaturated in a metal element or an insulator on the surface of a sample substrate is provided inside a vacuum vessel . An ion source for irradiating negative ions; and a deposition source for heating and evaporating the membrane substrate to deposit the membrane substrate vapor on the sample substrate surface. Provided is a film forming apparatus by negative ion irradiation and simultaneous vapor deposition, characterized by comprising a control means and performing film formation by dynamic mixing processing.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The invention of this application has the characteristics as described above, and an embodiment relating to a film forming method by negative ion irradiation and simultaneous vapor deposition of the invention of this application will be described below.
[0013]
The film forming method by negative ion irradiation and simultaneous vapor deposition of the invention of this application is performed inside a vacuum vessel. Inside the vacuum vessel, an ion source for irradiating the surface of the sample substrate with a negative ion beam, and a film substrate housed in the crucible are heated and evaporated to deposit on the surface of the sample substrate. Source. As the evaporation source, an electron beam evaporation source, a high-frequency heating evaporation source, or the like is used. Inside the vacuum vessel, vacuum deposition of the film substrate and negative ion beam irradiation are simultaneously performed, and a film composed of multiple elements is formed by a dynamic mixing process.
[0014]
In the film formation method of the invention of this application, the number of the ion sources and vapor deposition sources is not limited, and an optimal number is appropriately set according to the configuration and function of the film to be formed.
[0015]
In the present invention, the secondary electron emission generated by ion particle bombardment, which has been a problem in the conventional film formation method by positive ion irradiation, is balanced with the inflow of negative charges by negative ion irradiation. In the growth of films composed of materials and elements introduced as ions, the uncharged state continues, that is, the film can be made thicker by continuous film formation, and the density of the elements constituting the film High density and uniformization are realized.
[0016]
Negative ions as implanted ions are metal elements having almost no solid solubility in the insulator. For example, in addition to Cu, Co, Ni, Zn, Mo, Pd, Ag, Cd, Hf, Ta, W, Re And negative ions such as Ir, Pt, Au, and Hg. Further, if attention is paid to the advantage that supersaturation can be achieved rather than the solid solubility limit, negative ions of nonmetallic elements such as B, C, Si, P, Ge, As, Se, and Sb are also exemplified. On the other hand, the film substrate to be vapor-deposited may be various types of insulator materials. For example, in the case of optical use only, as a transparent substrate, for example, soda glass in addition to fused quartz or crystalline quartz SiO 2. , Al ₂ O ₃ , sapphire Al ₂ O ₃ , MgO, spinel MgO · n (Al ₂ O ₃ ), LiNbO ₂ , BaF _{2 and the} like.
[0017]
In the film forming method of the invention of this application, a film in which fine particles are dispersed is formed. The formed film is composed of a matrix material and fine particles dispersed and distributed therein.
[0018]
The fine particles are formed by agglomeration in the matrix material by promoting diffusion by negative ion implantation. For example, the fine metal particles are formed by injecting negative ions of a metal element that hardly dissolves in the film substrate. It is representative. In this case, the matrix material is formed by vapor deposition of a film substrate.
[0019]
The fine particles to be formed can have various diameters, but generally those having a diameter of 100 nm or less are exemplified. The fine particles can be single crystals.
[0020]
The fine particle dispersion film as described above can provide a nonlinear optical material.
[0021]
In the film forming method of the invention of this application, each particle bundle can be controlled with respect to a negative ion beam irradiated from the ion source to the sample substrate surface and a film base material deposited from the vapor deposition source to the sample substrate surface. Thereby, the composition, structure, and function of the formed film are controlled, and further, the non-equilibrium effect due to ions is also controlled. Specifically, for example, a beam profile monitor and a water-cooled Faraday cup are installed immediately in front of the sample substrate, and the spatial distribution of the negative ion beam and the current density of the negative ion beam are respectively measured quantitatively from the ion source. The ion beam irradiation amount is controlled. In addition, the vapor deposition source is provided with a shield so as to cover the vapor deposition source, and an injection hole for vapor deposition of the base material vapor onto the sample substrate and an injection hole for quantitatively measuring the vapor deposition rate of the base material vapor are provided. It has been. The film formed by the vapor injected from the injection hole for quantitatively measuring the vapor deposition rate of the substrate vapor is measured by, for example, a quartz oscillation type film thickness meter, and the output of the vapor deposition source can be controlled with reference to this film. Made.
[0022]
As described above, as the control factor of the particle bundle, the deposition rate of the film substrate and the negative ion implantation density (dose), that is, the current density (μA / cm ² ) are considered. By making this factor variable, the content of fine particles in the film and the particle size can be changed.
[0023]
The fine particle content is mainly determined by the deposition rate of the film substrate, and the particle size is determined by the negative ion implantation density.
[0024]
The invention of this application has the above-described features, and will be described more specifically with reference to examples.
[0025]
【Example】
As an embodiment of the invention of this application, SiO ₂ vacuum deposition as a film substrate of an insulator material and irradiation of a Cu negative ion beam are simultaneously performed on a fused quartz substrate, and a Cu-SiO ₂ film is formed by dynamic mixing treatment. Formed.
[0026]
A schematic view of the film forming apparatus used in this example is shown in FIG.
[0027]
A plasma sputtering type negative heavy ion source was used as the negative ion source. This ion source generates negative ions targeting elements from B to Au and accelerates them to 60 keV. In this example, irradiation was performed while controlling the particle bundle of the ion beam with a Cu negative ion beam at 60 keV and a current density of 5 to 50 μA / cm ² .
[0028]
The negative ion beam (1) emitted from the negative ion source passes through the vacuum duct and enters the high vacuum chamber. At the entrance of the high vacuum chamber, the negative ion beam (1) is shaped into a circular beam having a diameter of 40 mm by a quadrupole triplet lens and irradiated onto the sample substrate. In front of the sample substrate, a beam profile monitor for measuring the spatial distribution of the negative ion beam (1) and a water-cooled Faraday cup for measuring the current density of the negative ion beam were installed.
[0029]
On the other hand, an electron beam evaporation source was installed at the bottom of the high vacuum chamber, and SiO ² inside the crucible (2) constituting the evaporation source was evaporated onto the sample substrate. At this time, the deposition rate was set at 0.2 to 0.4 nm / s, and the composition of the film to be formed was controlled.
[0030]
The acceleration voltage of the electron beam (3) of the vapor deposition source was 3 keV, and the maximum rated current was 700 mA. Since the SiO ₂ vapor (4) whose traveling direction is not directed toward the sample substrate is unnecessary and obstructs the irradiation of the negative ion beam, the SiO ₂ vapor (4) does not enter the irradiation path of the negative ion beam. In addition, since it is effective to install a shield, a stainless steel shield (5) was installed so as to cover the vapor deposition source. The stainless steel shield (5) was provided with an injection hole (6) for depositing SiO ₂ vapor on the sample substrate. Furthermore, the stainless steel shield was provided with an injection hole for quantitatively measuring the deposition rate of SiO ₂ vapor.
[0031]
A fused quartz substrate (7), which is a sample substrate, is placed on a copper stage (8), and the angle formed by the normal direction of the substrate plane and the irradiation direction of the Cu negative ion beam, and the normal direction of the substrate plane and the SiO ₂ vapor. The angles formed by the injection directions were set to about 20 ° and about 15 °, respectively.
[0032]
By performing film formation using the above film forming apparatus, a Cu—SiO ₂ film in which Cu fine particles having a particle diameter of 3 to 10 nm are dispersed is obtained.
[0033]
Cu fine particles are uniformly distributed in the film. Moreover, it has been confirmed by observation with a transmission electron microscope that these Cu fine particles are single crystals.
[0034]
FIG. 2 illustrates a cross-sectional observation photograph by a transmission electron microscope of a Cu—SiO ₂ film (thickness 500 nm) formed at a SiO ₂ deposition rate of 0.4 nm / s and a current density of Cu negative ion beam of 20 μA / cm ² . Is.
[0035]
Further, regarding the Cu-SiO ₂ film in which 500 nm Cu fine particles are dispersed and formed, the formation conditions are set such that the current density of the Cu negative ion beam is set to 50 μA / cm ² and the deposition rate of the SiO ₂ vapor is set to 0.4 nm / s. A nonlinear optical property evaluation method (degenerate four-wave mixing method) was applied to investigate nonlinearity. The results are shown in FIG. Since the nonlinear reflectance is proportional to the square of the pump light intensity, it was confirmed that this thick film has a third-order nonlinearity.
[0036]
【The invention's effect】
The film forming method by negative ion irradiation / simultaneous vapor deposition and the apparatus of this application make it possible to stably form a film based on an insulator, such as a new thick film material having nonlinear optical characteristics, etc. Functional materials can be created.
[Brief description of the drawings]
FIG. 1 is a schematic view of a film forming apparatus used in an embodiment relating to a film forming method of the invention of this application.
FIG. 2 is a transmission electron micrograph in place of a drawing, illustrating a cross section of a Cu—SiO ₂ film formed by the film forming method of the invention of this application.
FIG. 3 is a diagram showing nonlinear optical characteristics of a Cu—SiO ₂ thick film.
[Explanation of symbols]
1 Negative ion beam 2 Crucible 3 Electron beam 4 SiO ₂ vapor 5 Stainless steel shield 6 Injection hole 7 Fused quartz substrate 8 Copper stage

Claims (7)

In a vacuum vessel, a film forming method by a dynamic mixing process in which ion irradiation from the ion source to the surface of the sample substrate and vapor deposition of the film base material on the surface of the sample substrate are performed simultaneously. The negative electrode of a non-metal element that can be supersaturated in a metal element or an insulator, and the film base that is co-deposited on the sample substrate is an insulator material, and the fine particles of the metal element or the non-metal element are film bases A method for forming a film by negative ion irradiation and simultaneous vapor deposition, comprising forming a fine particle dispersion film dispersed in a material . Membrane substrate _{is, SiO 2, Al 2 O 3} , MgO, MgO-Al 2 O 3, LiNb
The film forming method according to claim 1, wherein one or more of O ₂ and BaF ₂ are used. Negative ions are Cu, Co, Ni, Zn, Mo, Pd, Ag, Cd, Hf, Ta, W, Re, Ir, Pt, Au, Hg, B, C, Si, P, Ge, As, Se and 3. The film forming method according to claim 1, wherein the negative ion is any one of Sb . 4. The film forming method according to claim 1, wherein the fine particles have a diameter of 1 to 20 nm. The film forming method according to claim 1, wherein the fine particles are single crystals. The film forming method according to claim 1, wherein a nonlinear optical film is formed. 7. An apparatus for a method according to any one of claims 1 to 6, wherein an ion is irradiated inside the vacuum vessel with negative ions of a nonmetallic element that can be supersaturated in a metallic element or an insulator on the surface of a sample substrate. Source and a vapor deposition source for heating and evaporating the membrane substrate to deposit the membrane substrate vapor on the surface of the sample substrate, and having means for controlling the particle bundle of each of the negative ions and the membrane substrate evaporation particles An apparatus for forming a film by negative ion irradiation and simultaneous vapor deposition, wherein the film is formed by dynamic mixing.

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