JPS60186804A - Film having periodic multi-layered structure - Google Patents

Abstract

PURPOSE:To obtain a film which has a periodic multi-layered structure, is chemically and physically stable and is applicable to various electronic apparatus by laminating alternately silicon oxide films and metallic films at a specified film thickness ratio. CONSTITUTION:A substrate 1 is placed in an upper part and a cooling pipe is provided in the place of the substrate 1 to cool the substrate. The substrate 1 can be heated by a heater 2 if necessary. Thereare two vapor sources 31, 32 in the lower part to evaporate respectively SiO powder and cobalt metal. The inside of a vacuum vessel 100 is evacuated to a high vacuum of <=about 5X10<-6> Torr and thereafter the sources 31, 32 are moved to evaporate alternately Co and SiO thereby forming the films laminated periodically with Co and SiOx. Glass is used for the substrate and is subjected to the vapor deposition under water cooling. The film thickness is monitored by a quartz oscillation type film thickness gage 5. When the prescribed thickness is attained, a shutter is closed and the vapor sources are moved, then the shutter is opened to evaporate the other material.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is a method in which silicon oxide films and metal films, which are useful for scientific equipment and electronic equipment, are alternately laminated and the thickness of each film is kept constant. O' (Prior art and its problems) Generally speaking, the electrical, magnetic, and optical properties of a metal film change significantly when it is used for several hundred years or less. It is known that practically desirable properties can sometimes be obtained with ultra-thin films.However, in many cases, a single-layer ultra-thin film has too small a physical quantity to be applied to practical devices. Attempts have been made to increase the physical quantity by increasing the number of layers by sandwiching them between other substances. However, as the gold lJ4 film becomes thinner, its reactivity with oxidation and other substances increases, resulting in deterioration of the properties of the metal film and its reproducibility, and such attempts at multilayering have not been successful. 0 This is because a good thin film that does not react with the metal film and has a high protective effect against the metal film has not yet been found. In addition to the above-mentioned chemical properties, the thin film that separates the metal films (hereinafter referred to as a spacer) must have the property that it can be formed as a continuous film at a sufficiently thin film thickness. This is because, although increasing the thickness makes it easier to form a continuous film, the total thickness of the multilayered film becomes too thick and the cumulative effect of physical quantities decreases. Although various studies have been made so far as spacer materials, no material has been developed that satisfies all of the above characteristics and also satisfies practical rust requirements.

(Objective of the Invention) An object of the present invention is to improve the above-mentioned drawbacks of the prior art and to provide a chemically and physically stable periodic multilayer structure film.

(Structure of the Invention) That is, the present invention is a periodic multilayer structure film in which silicon oxide films and metal films are alternately laminated at a constant thickness ratio.

(Detailed explanation of the structure) As a result of extensive research by the present inventors regarding materials that satisfy the above-mentioned characteristics required for the spacer, they discovered that a silicon oxide film satisfies the requirements, leading to the present invention. . The silicon oxide film in the present invention is 8i0. Or Si
It refers to a film formed by a vacuum deposition method such as true nitrogen evaporation, sputtering, ion beam deposition, or ion blating using O as a source material. Usually, the film formed in this way is not necessarily 5i02 or SiO
However, depending on the film forming conditions, a film that deviates from stoichiometry may be obtained. Here, these are collectively referred to as SiOx. This flexible Siox m is a material well known to researchers of thin films and semiconductor materials. That is, Siox is amorphous and an electrical insulator,
It has good lubricity against metals, forms a uniform film, and is widely used as a protective film for metals. These characteristics are suitable for the spacer according to the present invention, but the characteristics of these Siox films relate to a film thickness of several hundred times more than several μm, and the thickness 1 μm required for the spacer of the present invention is
The characteristics of thin films below 00X are not clear. In particular, the behavior of multilayer films has been clarified for the first time by the present invention.

Various metal films can be used, but the most suitable material can be selected for the application. For example, as a magnetic recording medium or head material, magnetic metals such as Fe and C are used.
+., Ni and magnetic alloys thereof can be used. In addition to the magnetic metals mentioned above, low melting point semimetals, rare earth/transition metal amorphous alloys, etc. can be used as optical recording media using laser light. In addition, noble metals such as A, U, and PT, and heavy metals such as Ta and VV can be used. Specific examples of this X-ray application include filters for X-ray diffraction equipment, and X-ray exposure for forming fine patterns. Examples include mask patterns for devices, etc. Furthermore, when applied as an electrical resistance material, chromium, nichrome, etc. can be used as the metal film.

Periodicity according to the present invention means that metal films and spacer films are alternately laminated with a constant thickness. The reason why the thickness between each layer is constant is because the properties of the metal film depend on the thickness, and when controlling the properties of the ax layer film, it is desirable that the properties of each layer be constant. In the same sense, it is desirable that the thickness of each layer of the spacer film be constant.The thickness of each layer of the metal layer and spacer film varies depending on the application mentioned above, but it is generally desirable to be 2001 or less. This is because, in the case of a metal film, the crystal structure and fine structure change at around 200X, and desired characteristics for the application can be obtained. The thickness of the spacer film must be determined in consideration of the method of detecting the physical properties of the multilayer film, but normally a value of 200X or less is desirable, similar to the metal film.

The most common method to confirm the periodicity of multilayer films is to use X-ray diffraction. When the metal film and the spacer film are each created uniformly and have clear interlayer separation, 2
An X-ray diffraction peak satisfying dSInθ=nλ (d: interplanar distance, 02 diffraction angle, n: reflection order, λ: X-ray wavelength) is obtained. As the periodicity becomes better, the half-value width of the diffraction peak becomes narrower, and higher-order diffraction peaks are also observed.

From this, the quality of the periodicity of the multilayer film can be determined. The diffraction peak intensity varies depending on the materials of the metal film and the spacer film, but it is thought that the intensity increases mainly as the difference in the atomic scattering factors for X-rays between the amounts of the two types of substances increases.

The present invention will be explained in detail below using examples.

(Example 1) Using a vacuum evaporation apparatus as shown in FIG.
If necessary, the substrate 1 can also be heated by the heater 2. At the bottom are two evaporation sources 31, 32, which evaporate 8i0 powder and cobalt (CO) metal, respectively. First, after evacuating the entire vacuum chamber to a high vacuum of 5 X 10-6 Torr or less, move the evaporation sources 31 and 32 to evacuate Co and Si.
C by evaporating O alternately.

A film was created in which SiOx and SiOx were periodically stacked. Glass was used as the substrate, and the film was deposited while cooling with water.The zero film thickness was monitored using a crystal vibrating film thickness gauge 5. When the film reached a predetermined thickness, the shutter was closed, the evaporation source was moved, and the shutter was opened again. The process of opening and depositing the other-power substance was repeated. The deposition rates of both Co and SiOx were approximately IJ/sec, which was adopted to accurately control the film thickness of each layer. The SiOx film deposited in this way has a refractive index of 1.6 in visible light, and is expected to have a composition between that of 5i02 and SiO.
The Ox film was 100X thick to protect the top Co film.

Figure 2 shows CuK at a small angle of a multilayer film in which Co was deposited at a thickness of 80X and SiOx was alternately deposited 10 times at a thickness of 15X.
X-ray diffraction peaks using CA rays are shown. If we add the distance d between the surfaces, the reflection order n = 1 and 76.81゜n =
7 and it was 97X. In X-ray diffraction, it is thought that higher angles show more accurate values, so when d=97X is used, it is found that it matches well with the period of 95X set by the reading of the film thickness meter. From this fact and the fact that a cylindrical diffraction peak of the 8th order is obtained, it can be seen that the present multilayer film has an excellent periodic structure.

Next, depending on the number of periodic layers, the height and half-width of the X-ray diffraction peak,
The following table shows how the strength changes. From this table, even when the number of layers m is 2, a large strength peak appears, and even when m increases, the strength does not increase much, but It can be seen that the half-width is small and the peak is sharp.The above results show that such a periodic multilayer structure film can efficiently reflect specific X-ray wavelengths by changing its period. Therefore, the o5iOx-metal multilayer film, which can be used as a filter or a mask material of X%1, has a large difference in atomic scattering factors, and is therefore advantageous in applications where the diffraction intensity is not as strong as that of other multilayer films.

(Example 2) In the same manner as in Example 1, in addition to the 810x-Co multilayer, 8i0x-Fe, 5iOx-Ni, 5iOx-
Create a multilayer film of In, 5iOx-Au, and investigate these optical coincidences. J4 solid.

In all these multilayer films, the thickness of Siox is 1
Below 5X, the optical properties of the film in the visible to near-infrared light range (
It has been found that the fouling rate R1, transmittance T, and absorption rate A) do not depend on the thickness of 8 r Ox. The optical properties in this case are
When the thickness of SiOx% was set to zero, it almost matched that of a metal single/m film, which is equivalent to an all-metal film.

This means that under these conditions, it is possible to change the thermal and electrical properties without changing the optical properties by multilayering. Repeated reflection interference appears, and by adjusting the thickness, the reflectance can be lowered and the absorption rate in the metal film can be increased. For example, Co40
A multilayer film of 1-810x repeated 10 times, with a single Siox film thickness of 15x.

When changing to 50X, 100X, and 150X, the reflectance and transmittance changed to 53%, 7%, 40%, 6%: 27%, 5%: 22%, and 4%, respectively.

When these films are irradiated with a focused semiconductor laser, it is possible to record in a mode in which the reflectance increases with the power and irradiation time.For example, Co(80X)-8iOx(15
X) In the case of a 10-times edge-turned multilayer film, the recording power is 5 mW,
With an irradiation time of 500 n5ee, a bit with a diameter of about 1 μm could be recorded, and the reflectance of the bit was increased by 8% from the initial value.

In this case, IMA is used for P as the substrate material,
The numerical aperture of the condenser lens was 0.55.

No change was observed in these optical properties even after being left in a high temperature and high humidity environment for more than one month. For comparison, the weather resistance of a Co monolayer film obtained under similar manufacturing conditions was 1.
Deterioration due to oxidation was observed after being left for ~2 weeks.

As a result of the above, such a periodic multilayer structure film can be used as a chemically stable optical element, optical disk, etc., since the optical properties can be controlled arbitrarily by changing the period.

(Example 3) 8i0x-C was applied on a glass substrate in the same manner as in Example 1.
An electric resistor was manufactured by forming a multilayer film. By using a periodic multilayer structure film, it became possible to set the electrical resistance value more precisely than with a cermet film, and the heat resistance and chemical stability were improved.

(Example 4) A multilayer film of 5iOx-Fe was formed in the same manner as in Example 1 to obtain a magnetic recording medium.

In addition to having good magnetic recording properties, the weather resistance is also significantly improved compared to a single layer film. (Effects of the Invention) As is clear from the above examples, the present invention has developed a chemical composition that can be widely applied to various electronic devices. A periodic multilayer structure film that is physically and physically stable can be obtained.

[Brief explanation of drawings]

Figure 1 is a diagram showing an example of a vacuum evaporation apparatus for carrying out the present invention, and Figures 2 (at to (C) are diagrams showing X-ray diffraction peaks of an example of the periodic multilayer structure film of the present invention. O In the figure, l is the substrate, 2 is the heater, 5 is the film thickness gauge, 31
．． 32 is an evaporation source, and 100 is a vacuum chamber. 2 Diffraction hardness

Claims (1)

[Claims] A periodic multilayer structure film characterized in that a silicon oxide film and a metal film are alternately stacked at a constant film thickness ratio.