JP2007146214A - Manufacturing method of phase separation film and structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phase separation film manufacturing method for enhancing control of the incident energy of film deposition particles and the degree of phase separation. <P>SOLUTION: The phase separation film manufacturing method comprises: a step of generating arc plasma 24 of a cathode material by a cathode arc discharge; a step of irradiating a substrate 23 with ions in the arc plasma; and a step of depositing a film constituted of a material of the composition for phase separation on the substrate 23 with the ions. The material of the composition for phase separation is constituted of aluminum, silicon, aluminum and germanium, or aluminum and silicon and germanium having the composition of Al<SB>X</SB>(Si<SB>Y</SB>Ge<SB>1-Y</SB>)<SB>1-X</SB>(0.3≤X≤0.8, 0≤Y≤1). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a phase separation membrane and a method for producing a structure. In particular, the present invention relates to a method for producing a phase separation membrane formed using a eutectic material. The present invention also relates to a method for producing a structure using the phase separation membrane.

  As a method for easily forming a fine structure that exceeds a conventional semiconductor process in a large area, a method in which a structure is naturally formed, that is, a method using a self-organization phenomenon of a material has attracted attention. Examples of nanostructures produced using the self-organization phenomenon include a porous film produced by, for example, anodizing aluminum or anodizing silicon.

  In the anodic oxidation of aluminum, a porous anodic oxide film can be obtained by anodizing an aluminum substrate in an acidic electrolyte such as sulfuric acid, oxalic acid, or phosphoric acid (see, for example, Non-Patent Document 1). A characteristic of this porous anodic oxide film is that a very fine cylindrical pore having a pore diameter of several nanometers to several hundred nanometers is divided by an alumina partition wall at intervals of several tens of nanometers to several hundred nanometers and arranged in parallel. It has a geometric structure. The cylindrical pores have a high aspect ratio and are excellent in depth and cross-sectional diameter uniformity. Further, the structure of the porous anodic oxide film can be controlled to some extent by changing the anodic oxidation conditions. For example, it is known that the pore diameter can be controlled to some extent by etching the partition wall alumina using phosphoric acid or the like using the anodizing voltage, the pore interval using the anodic oxidation time, and the pore depth using the anodic oxidation time. ing.

  In silicon anodization, when a voltage is applied in a hydrofluoric acid aqueous solution using a p-type silicon substrate as an anode, porous silicon is formed (see, for example, Non-Patent Document 2). The porous silicon has innumerable pores having a pore diameter of 1 nm to several tens of nm, and the pore diameter, the shape and density of the pores can be changed depending on the anodizing conditions.

  By filling such fine pores with metals and semiconductors, various nanodevices such as magnetic recording media, magnetic sensors, EL light emitting elements, electrochromic elements, optical elements, solar cells, gas sensors, etc. Application is expected.

  It is also known that a thin film made of a material composition having a eutectic point, for example, an aluminum silicon mixed film 11 is formed on the substrate 10 in a non-equilibrium state by sputtering (see FIG. 8). A thin film having a phase-separated structure grows into a nanoscale cylindrical aluminum portion 12 mainly composed of aluminum and a partition wall 13 mainly composed of matrix silicon surrounding the aluminum portion 12. Further, by anodizing or etching the cylindrical aluminum portions 12 separated from each other by the partition walls 13, a nanostructure having extremely fine pores exceeding both anodized alumina in pore diameter and pore spacing can be provided (Patent Document). 1).

Further, the diameter and shape of the cylindrical aluminum portion 12 and the thickness of the partition wall 13 depend on the diffusion of sputtered particles on the substrate surface, and phase separation is promoted by promoting the diffusion (see Patent Document 2).
JP 2003-266400 A JP 2005-068558 A R. C. Furneaux, W.M. R. Rigby & A. P. Davidson “NATURE” Vol. 337, p147, 1989 D. R. Turner “J. Electrochem. Soc” 105, 402, 1985

  In Patent Document 2, a substrate bias is applied during sputtering, and the substrate surface is bombarded with argon ions in the sputtering plasma. That is, most of the sputtered particles themselves are electrically neutral, and the incident energy cannot be controlled by the substrate bias. Therefore, the diffusion of the sputtered particles on the substrate surface is indirectly promoted by applying energy to the sputtered particles flying on the substrate via the argon ions.

  For this reason, if it is possible to improve the incident energy of the film-forming particles themselves, it is considered possible to obtain a thin film having a nanostructure in which phase separation is further promoted. Further, if it becomes possible to directly promote the diffusion of the film-forming particles on the substrate, that is, if the incident energy of the film-forming particles incident on the substrate can be directly controlled, the phase separation film It is considered that the controllability with respect to the degree of phase separation and the structure is further improved.

  In view of the above, the present invention provides a method for producing a phase separation film, which can improve the controllability of the incident energy and the degree of phase separation of film-forming particles. The present invention also provides a method for producing a structure formed using the phase separation membrane.

The above problems are solved by the following means of the present invention.
That is, a step of generating an arc plasma by cathodic arc discharge, irradiating the substrate with first and second ions in the arc plasma, a region containing the first ions on the substrate, and the second A method for producing a phase separation membrane, comprising the step of forming a membrane that undergoes phase separation in a region containing ions.

The cathode arc discharge preferably generates arc plasma of the cathode material.
The energy of ions incident on the substrate is preferably 20 eV or more and 200 eV or less.

It is preferable to include a step of controlling the energy of ions incident on the substrate.
The growth rate of the film is preferably 150 nm / min or less.
The average diameter in the minor axis direction of one phase portion of the phase separated structure is preferably 1 nm or more and 20 nm or less.

It is preferable to include a step of selectively removing one phase portion of the phase separated structure.
The material having a composition for phase separation is preferably a material having a eutectic point.
It is preferable that the material having a composition for phase separation is silicon, germanium, or a material containing silicon germanium.

Aluminum and silicon, aluminum and germanium having a composition of Al _x (Si _Y Ge _1-Y ) _1-X (0.3 ≦ X ≦ 0.8, 0 ≦ Y ≦ 1) Or aluminum, silicon and germanium.

Preferably, the method includes a step of selectively removing the phase-separated aluminum portion.
The structure manufacturing method includes a step of obtaining a phase separation membrane by the above method, a step of selectively removing one phase portion of the phase separated structure of the membrane, and at least a part of the removed phase portion. And a step of depositing a material.

  INDUSTRIAL APPLICABILITY The present invention can provide a method for producing a phase separation film that can improve the controllability of incident energy and phase separation degree of film-forming particles. Moreover, this invention can also provide the manufacturing method of the structure formed using the said phase-separation membrane.

Embodiments of the present invention will be described below.
FIG. 1 is a schematic view showing an example of an embodiment of a method for producing a phase separation membrane of the present invention. First, a cathode 21, an anode 22 and a substrate 23 made of a material having a composition to be phase-separated are arranged in a evacuated container 20, and the cathode 21 is evaporated by cathode arc discharge. The evaporated cathode material is turned into plasma, and the substrate 23 disposed in the vacuum vessel is irradiated with ions in the arc plasma 24 to form a cathode material film on the substrate 23. Since the ions in the arc plasma generated by such a cathodic arc method have a high energy of 20 to several tens eV, the adhesion to the substrate is very good, and a dense film can be obtained. There is. Also, since the ionization rate of the cathode material is very high compared to sputtering, the incident energy of ions (film formation particles) incident on the substrate is directly controlled by placing a bias power supply 25 and applying a bias to the substrate. It becomes possible to do. That is, since the film-forming particles are incident at a high energy, diffusion of the film-forming particles on the substrate is promoted, and a favorable phase separation film can be obtained from the initial growth layer, and the controllability by bias is further improved. There is. The substrate bias to be used is not particularly limited, such as a DC bias, an RF bias, and a DC pulse bias.

It is desirable that the energy of ions incident on the substrate is 20 eV or more and 200 eV or less, preferably 40 eV or more and 100 eV or less.
At this time, when the growth rate of the film is extremely high, the phase separation is not sufficiently performed, and the phase separation film can be sufficiently obtained by setting the growth rate to 150 nm / min or less, preferably 100 nm / min. From the viewpoint of productivity, the lower limit of the growth rate is 0.1 nm / min or more, more preferably 0.5 nm / min or more.

  Furthermore, it is possible to change the shape and size of the resulting structure depending on the material and film formation conditions. When the structure shown in FIG. 8 is used in which one of the cylindrical materials is surrounded by the other material, 2 may have a columnar structure 30 whose cross-sectional shape is distorted. Here, the size is defined as the average diameter in the minor axis direction of the columnar portion shown in FIGS. Although the average diameter varies depending on the material system to be used, it can be changed within a range of approximately 1 to 20 nm depending on the material system. In addition, when FIG. 2 is further distorted to form a lamellar (layered) structure, the shorter width of the layer is defined as the average diameter in the minor axis direction.

  In the cathode arc discharge as described above, coarse particles (droplets) of the cathode material generated at the cathode spot may fly to the substrate and deteriorate the roughness and characteristics of the film surface. When it is necessary to prevent this, it is preferable to adopt a method of filtering with a magnetic field or a shield plate before the generated droplets fly to the substrate, or a discharge method for suppressing the generation of droplets. Although not particularly shown in FIG. 1, in the present invention, it is desirable to remove and reduce droplets using these known methods from the viewpoint of forming a high-quality film. Further, any known means for removing and reducing droplets may be incorporated in the embodiment shown in FIG.

  Further, the method for forming a mixed film having a composition for phase separation by the cathode arc method on the substrate is not particularly limited to the above method, and the same substrate is used by using a plurality of evaporation sources made of different cathode materials. A method of irradiating ions in the arc plasma may be used.

  Moreover, about the mixed film of the composition which carries out the phase separation formed by the cathode arc system as mentioned above, it is also possible to form cylindrical or lamellar pores by removing one phase separated portion. Furthermore, the structure formed by depositing a material in the formed pores can be a structure having functionality depending on the deposited material. That is, a structure that can be applied to various devices such as a magnetic recording medium, a magnetic sensor, an EL light-emitting element, and an electrochromic element can be obtained depending on the kind of a material to be deposited such as a magnetic substance or a semiconductor. The process of depositing the material in the pores may be, for example, plating, but is not particularly limited to this, and is a method such as CVD (chemical vapor deposition) or PVD (physical vapor deposition). May be.

  Note that the first ion and the second ion contained in the arc plasma are deposited on the substrate, and the first region mainly composed of the first ion, and mainly composed of the second ion. The second region to be phase-separated.

  Here, the boundary between the first region and the second region does not have to be strictly separated. If it can be confirmed by observation with an electron microscope that there are two regions, or the first or second region can be selectively removed by etching or the like by chemical treatment, it corresponds to the phase separation membrane according to the present invention. .

  Note that the second ion contained in the first region is 10 atomic% or less, more preferably 5 atomic% or less, and still more preferably 3 atomic% or less. Further, the first ion contained in the second region is 10 atomic% or less, more preferably 5 atomic% or less, and still more preferably 3 atomic% or less.

  Moreover, two or more types (for example, three types and four types) of ions contained in arc plasma may be sufficient.

  Examples of the present invention will be described below. The material system that can be used in the present invention may be any material system that has a composition having a eutectic point and phase-separates. In the embodiment, only an aluminum silicon mixed film will be described as one of such material systems.

  In this embodiment, an aluminum silicon mixed film is described as a film having a phase-separated structure, but similar results can be obtained with an aluminum germanium mixed film and an aluminum silicon germanium mixed film.

Example 1
In this example, an aluminum silicon mixed film was formed by a cathodic arc method.
The cathode arc discharge generator used in this example generates pulsed arc discharge between the cathode and anode by intermittently charging and discharging the capacitor, and the cathode and anode are coaxial. By arranging it, the number of droplets is reduced.

An aluminum silicon alloy was attached to the cathode arc discharge generator as a cathode material, and an aluminum silicon mixed film was formed by a cathode arc method. Film formation conditions were as follows: capacitor capacity 2200 μF, arc voltage 60 V, discharge interval 1 second, distance 70 mm between cathode and substrate, and vacuum degree 5.0 × 10 ⁻⁵ Pa. The growth rate of the film was 1 nm / min.

  First, when the composition ratio of the aluminum silicon mixed film formed from the cathode material was quantitatively analyzed by ICP (inductively coupled plasma emission spectrometry), the ratio of silicon in the film was 35 atomic%. Here, atomic% is the proportion of atoms contained in the film.

  Next, a film was formed on the Si (100) substrate by the cathodic arc method so that the film thickness of the aluminum silicon mixed film was 100 nm. After the film formation was completed, the phase-separated nanostructure formed on the film surface was observed. At this time, in order to clearly observe the state of phase separation, the aluminum cylinder was dissolved by wet etching using a 2.8 wt% aqueous ammonia solution at 22 ° C. to form pores 41 as shown in FIG. The surface of the sample was observed with an FE-SEM (field emission scanning electron microscope).

  As a comparative example, a sample in which an aluminum silicon mixed film having the same composition ratio and film thickness was formed by sputtering without bias was prepared, and wet etching was performed in the same manner, and the sample surface was observed with FE-SEM.

  When both were compared, in any sample, innumerable pores 41 perpendicular to the substrate having a pore diameter of about 5 to 10 nm as shown in FIG. 3 were randomly formed. SEM images obtained by observing both surfaces were processed with image processing software, and a histogram was prepared for the variation in pore diameter. The half-value width of the sample formed by the cathodic arc method was 2 nm, whereas sputtering was performed. What was produced in (4) was 4 nm. In other words, it is considered that the sample formed by the cathodic arc method has a higher uniformity of the hole diameter because the energy of the incident particles is higher and the diffusion on the substrate is promoted.

  In addition, in the sample formed by the cathodic arc method, as shown in FIG. 4, there are some domains 51 in which pores 50 are regularly arranged in a honeycomb shape in a very small region of about 100 nm square, It is thought that the effect by having promoted the diffusion on a substrate is appearing rather than the sample produced by sputtering.

  As described above, by forming the aluminum silicon mixed film by the cathodic arc method, the diffusion of aluminum and silicon on the substrate is promoted, and the phase separation of aluminum and silicon is compared with sputtering when no bias is applied. Can be further promoted.

Example 2
In this example, an aluminum silicon mixed film was formed by a cathodic arc method. In particular, the phase separation of the initial growth layer of the aluminum silicon mixed film formed by the cathodic arc method was investigated.

  Under the same conditions as in Example 1, an aluminum silicon mixed film was formed on a Si (100) substrate so as to have a film thickness of 5 nm by the cathodic arc method and biasless sputtering.

  Further, the aluminum cylinder was dissolved by wet etching in the same manner as in Example 1, and then the sample surface was observed by FE-SEM. The sample formed by the cathodic arc method had almost the same structure as that observed in Example 1. On the other hand, in the sample produced by sputtering, no clear pores are observed as observed in Example 1, the diffusion length of aluminum and silicon is short, and it is considered that phase separation is not sufficiently advanced in the initial stage of growth. .

  As described above, by forming the aluminum silicon mixed film by the cathodic arc method, the diffusion of aluminum and silicon on the substrate is promoted, so that a good phase separation structure can be obtained from the initial growth stage of the aluminum silicon mixed film. It was confirmed that it was obtained.

Example 3
This embodiment relates to the formation of an aluminum silicon mixed film by a cathodic arc method. In particular, when the film was formed by the cathode arc method, the energy of ions incident on the substrate was controlled by applying a bias to the substrate.

  Similar to Example 1, an aluminum silicon mixed film was formed on a Si (100) substrate by a cathodic arc method so as to have a film thickness of 100 nm. At this time, a DC bias was applied to the substrate so that the substrate potential was negative with respect to the ground. After film formation, the aluminum cylinder was dissolved by wet etching in the same manner as in Example 1, and then the sample surface was observed with FE-SEM, and image processing of the SEM image was performed.

  In the sample with a bias of −40 V, the hole diameter is about 10 to 13 nm, which is larger than that in the case of no bias in Example 1, and the uniformity of the hole diameter is improved with a half-value width of 1.5 nm. It was confirmed that diffusion was promoted.

  However, when a larger negative bias was applied, the pore diameter increased and at the same time the deposit spattered by high-energy ions, and no film was formed on the substrate at -200V. For this reason, it was confirmed that the bias potential is preferably −200 V or less. In the cathode arc method, although ions are considered to have an energy of approximately 20 eV or more, it is considered that the energy of ions incident on the substrate is preferably 20 eV or more and 200 eV or less.

  As described above, when an aluminum silicon mixed film is formed by the cathodic arc method, by applying a bias to the substrate, the energy of ions incident on the substrate is controlled to diffuse aluminum and silicon on the substrate. It was confirmed that a better phase separation structure can be obtained.

Example 4
This embodiment relates to a structure formed by using an aluminum silicon mixed film formed by a cathodic arc method. In particular, the present invention relates to a structure formed by depositing a material in pores formed by removing an aluminum portion.

  After forming a film on the Si (100) substrate by sputtering so that the thickness of Ti is 5 nm and the thickness of Cu is 20 nm thereon, an aluminum silicon mixed film is further formed on Cu under the same conditions as in Example 1. The film was formed by the cathodic arc method so as to have a film thickness of 50 nm.

  Next, the sample which has the pore 61 penetrated to Cu60 which is a base layer as shown in FIG. 5 was produced by melt | dissolving an aluminum cylinder by wet etching similarly to Example 1. FIG.

  Subsequently, by using Cu as a base layer as a cathode, Co was deposited in the pores of the prepared sample by electroplating. For Co plating, a mixed solution of cobalt (II) sulfate heptahydrate 0.3 mol / L and boric acid 0.3 mol / L is used at 24 ° C., the reference electrode is Ag / AgCl, and the counter electrode is platinum. The electrodeposition potential was -1.0V. As shown in FIG. 6, plating was performed until Co70 was deposited in the pores and Co was overflowing from the pores. The sample surface was polished using a diamond slurry to remove Co71 overflowing from the pores, and a structure as shown in FIG. 7 was formed.

  The structure shown in FIG. 7 can be used for, for example, a magnetic recording medium by using the magnetization of Co80, which is a magnetic material deposited in the pores. In other words, in the structure obtained by depositing the material in the pores formed by removing the aluminum part of the aluminum silicon mixed film formed by the cathodic arc method, it functions on the structure by depositing the magnetic material. It is possible to impart sex.

  In this embodiment, only a magnetic material is described as a material for imparting functionality, but the material deposited in the present invention is not particularly limited to a magnetic material.

  The present invention can obtain a phase separation film that can improve the controllability of the incident energy and the degree of phase separation of the film-forming particles, so that a magnetic substance, a semiconductor, or the like is deposited in the pores of the film. Thus, it can be used in a method for manufacturing a structure such as a magnetic recording medium, a magnetic sensor, a device such as an EL light emitting element, or an electrochromic element.

It is a schematic diagram which shows an example of embodiment of the manufacturing method of the phase-separation membrane of this invention. It is a schematic diagram of the phase-separated film | membrane which has a columnar structure where the cross-sectional shape of the cylinder was distorted. It is the schematic diagram which formed a pore by removing a part of phase separation membrane. It is the schematic diagram which formed a pore by removing a part of phase separation membrane. It is a schematic diagram of the sample which has the pore penetrated to a base layer. It is a schematic diagram of the sample which plated until it became the state where Co overflowed from the pore. It is a schematic diagram of the sample which removed Co overflowing by surface polishing. It is a schematic diagram of a phase separation membrane.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Substrate 11 Aluminum silicon mixed film 12 Cylindrical aluminum part 13 Silicon partition 20 Container 21 Cathode 22 Anode 23 Substrate 24 Arc plasma 25 Power source for bias 30 Columnar structure 40 Substrate 41 Pore 42 Partition 50 Pore 51 Domain 60 Cu
61 pore 70 Co
71 Co overflowing
80 Co

Claims (12)

  A step of generating an arc plasma by cathodic arc discharge; irradiating the substrate with first and second ions in the arc plasma; and a region containing the first ions and the second ions on the substrate. A method for producing a phase separation membrane, comprising the step of forming a membrane that undergoes phase separation in a region to be contained.   2. The method for producing a phase separation membrane according to claim 1, wherein arc plasma of a cathode material is generated by the cathode arc discharge.   The method for producing a phase separation film according to claim 1 or 2, wherein the energy of ions incident on the substrate is 20 eV or more and 200 eV or less.   The method for producing a phase separation membrane according to any one of claims 1 to 3, further comprising a step of controlling energy of ions incident on the substrate.   The method for producing a phase separation film according to any one of claims 1 to 4, wherein the growth rate of the film is 150 nm / min or less.   6. The method of manufacturing a phase separation membrane according to claim 1, wherein an average diameter in a minor axis direction of one phase portion of the phase separated structure is 1 nm or more and 20 nm or less.   The method for producing a phase separation membrane according to any one of claims 1 to 6, further comprising a step of selectively removing one phase portion of the phase separated structure.   The method for producing a phase separation membrane according to any one of claims 1 to 7, wherein the material having a composition for phase separation is a material having a eutectic point.   9. The method for manufacturing a phase separation film according to claim 1, wherein the material having a composition for phase separation is silicon, germanium, or a material containing silicon germanium. Aluminum and silicon, aluminum and germanium having a composition of Al _x (Si _Y Ge _1-Y ) _1-X (0.3 ≦ X ≦ 0.8, 0 ≦ Y ≦ 1) The method for producing a phase separation membrane according to claim 9, comprising aluminum, silicon, and germanium.   The method for producing a phase separation membrane according to claim 10, further comprising a step of selectively removing the phase-separated aluminum portion.   A step of obtaining a phase separation membrane by the method according to any one of claims 1 to 11, a step of selectively removing one phase portion of the phase separated structure of the membrane, and at least a part of the removed phase portion A method for manufacturing a structure, comprising: depositing a material on the substrate.

Images