JPH0328124A - Production of superconducting oxide thin film and zinc oxide thin film - Google Patents

Abstract

PURPOSE:To reduce incidental amount of high energy oxygen ion to a substrate, keep the chemical composition of a crystal to a stoichiometric composition and reduce the lattice defect by providing a mask at a specific position when superconducting oxide thin film containing copper is produced using planer type magnetron sputtering. CONSTITUTION:When the objective superconducting oxide thin film containing copper is produced by planer type magnetron sputtering, a mask 3 crossing with at least a part of sputter grains is provided in the space area formed of erosion area 2 of superconducting oxide target 1, oxide thin film on a substrate 4 and linear locus of sputter grains which starts from erosion area 2 and reaches oxide thin film. Then the superconducting oxide thin film is produced by carrying out planer type magnetron sputtering. Thereby incidental amount of high energy oxygen ion to the substrate 4 is reduced by a mask 3 and the objective superconducting oxide thin film having superconducting characteristics can be produced.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for producing superconducting oxide thin films and zinc oxide #t films by planar magnetron sputtering, and particularly to methods for producing superconducting oxide thin films and zinc oxide #t films by planar magnetron sputtering. Relating to a manufacturing method.

[Conventional technology]

Oxide ceramics are used as structural materials as well as electromagnetic, 5Y: scientific. It has come to attract attention as a mechanically functional material. For example, zinc oxide is used as a piezoelectric material and as a transparent conductive material.
) is used as an electro-optical material, and Y-Ba-Cu-o complex oxide (YBCO) is used as a superconducting material.

These materials must be used with I! It is often made into a t-film, and sputtering is often used as the method because it can be applied even to materials with high melting points and is excellent in mass production. In particular, planar magnetron sputtering has the advantage that it can be used even at low gas pressures because it uses a magnetic field to increase ionization efficiency, and that there is little film impact caused by secondary electrons.

[Invention tries to solve! ! Title]

However, during sputtering of an oxide target, most of the oxygen in the oxide target is sputtered and accelerated in the form of oxygen ions, becoming high-energy particles that impinge on the thin film on the substrate. In the case of , the CII1tl configuration of the crystal deteriorates, resulting in a decrease in piezoelectric properties, and in the case of a YBCON film, Ba and Cu atoms (particularly Cu
atoms) from the thin film and the chemical composition of the crystal deviates from the stoichiometry. There were problems such as poor conduction characteristics.

This invention was made in view of the above-mentioned points, and its purpose is to prevent scattering ions sputtered from an oxide target from forming a thin X-ray on a substrate.
It is an object of the present invention to provide a method for manufacturing a superconducting oxide thin film or a zinc oxide thin film having excellent electrical properties by forming a thin film having a crystal chemical composition Q and excellent crystallinity by avoiding the incident light.

[Means to solve the problem]

According to the present invention, the above-mentioned objects are achieved by 1) 'A' by planar magnetron sputtering;
A method for producing a superconducting oxide thin film comprising two regions 3 of a C1 superconducting oxide target, an oxide thin film on a substrate 4, and sputtering starting from the two regions forming the oxide thin film. 2) A method for producing a zinc oxide thin film by planar magnetron sputtering, in which a mask 3 intersecting at least a part of the spatial region formed by the orthogonal trajectory of the particles is provided to perform the spacing. , in a spatial region formed by the erosion region 3 of the oxide target, the zinc oxide thin film on the substrate 4, and the linear trajectory of the sputtered particles starting from the erosion region and ending with the zinc oxide thin film, at least By performing sputtering with a mask 3 that intersects a part of the sputtering, a slow M. I can be killed.

Superconducting oxides include rare earth elements, alkaline earth metals,
w4, complex oxide consisting of oxygen, Bl (bismuth)*
Sr (strontium) SCa<calcium), C
Composite oxide consisting of u < @), B1 (bismuth),
Pb (lead) + br (strontium), Ca
(calcium), Cu (copper), U (thallium), Ba (barium), Ca(
A composite oxide consisting of (calcium) + Cu (steel) is used.

Sputter particles are sputtered from a ridged target by sputtering6.
Among the particles that fly out from this, oxygen is mainly in the form of ions, and the other elements are in the form of atoms. The r1l elementary ion is '! ! It is thought that the field speeds up the particles, making them high-energy particles that move along relatively straight trajectories, while other elements are not slowed down by the field and repeatedly collide with the sputtering gas, moving along disordered trajectories. .

[Effect]

Oxygen ions colliding with the mask are blocked in their path and cannot enter the substrate. On the other hand, elements other than oxygen enter the substrate after being disturbed by the sputtering gas and form a square.

[Central example]

A central embodiment of the present invention will be briefly described with reference to the drawings.

(Example 1) A film was formed using a DC magnetron type sintering device using a ZnO sintered body with a diameter of lOG as a target. In order to make the oxide target conductive, it was sintered using a known method. The material was heat treated at 800° C. in a hydrogen stream and reduced. Main sputtering conditions are shown in 1st fi. Under this condition, the two region regions of the oxide target have a ring-like shape surrounded by concentric circles with an inner diameter of 4Q IIm and an outer diameter surface.

The substrate used was a quartz plate with a size of 10 mm square, and 1 square plates were arranged so as to be located directly above the erosion area. In addition, the inner diameter is 4Q II, which is the same as the shape of the erosion area, and the outer diameter is 65.
Snow l ring-shaped stainless steel mask (thickness Q. 5
ra) was fabricated and placed directly above the erosion region and midway between the oxide target and the substrate as shown in Figure 1 (only two substrates are shown and the other six are omitted).

It is placed symmetrically with respect to the center of the ring. ).

The distance between the oxide target and the substrate was 401 m, and the distance between the oxide target and the mask was 211 m, and the mask was fixed to the vacuum container with a stainless steel wire.

That is, the t position of the mask is at ground potential. This condition
In Table 1, a film was prepared using a conventional method both with and without a mask, and its properties were compared. When the crystal structure was examined by X-ray diffraction, it was found that the thin pancreas deposited using a mask was 0.
．． The C-axis was oriented at any gas pressure of 5 to 10 Pa, but the film filmed by the conventional method without using a mask had a 10P orientation.
Only the film formed under a has a C-axis orientation, and at other gas pressures it has a (100). Peaks indicating other orientations such as (101) were also observed. In the case of the conventional method that does not use a mask, oxygen ions or neutralized oxygen atoms are incident on the substrate with high precision, which is thought to disturb the crystallinity. By increasing the gas pressure, the energy of high-energy particles is reduced by scattering with the sputtering gas,
Although a good C-axis orientation could be obtained, other sputtered particles also lost their directionality and the distribution of incident angles on the substrate broadened, resulting in a thin film with a columnar structure and an uneven surface. By inserting the mask between the two region regions of the oxide target and the substrate in this way, it became possible to produce a ZnO thin film with excellent C@ conformation and # film quality with good reproducibility.

(Execution 9tl2) A film was formed using an RF Magne 1 Ron type sputtering device using a YBa2CuaO7-X (YBCO) sintered body with a diameter of 15α as a sintered target. The oxide targets are listed in Table 2 Y203. BaCO3. CuO was used as a raw material, and the material was prepared using a known technique, calcined, shaped, and fired. Some films were formed under the conditions shown in Table 2. The inner and outer diameters of the erosion area at this time were 55 mm and IQQ@l, respectively. As shown in Figure 2, one substrate was placed directly above the center of the oxide target, and a ring-shaped mask was made so that all points on the substrate were hidden from the erosion area of the oxide target. , inserted at an intermediate height between the oxide target and the substrate. As in Example 1, differences in characteristics depending on the presence or absence of a mask were investigated.

Figure 3 shows the relative film speed [(μfi/h
) shows the gas pressure dependence of At 2 Pa or more, when a mask is provided, the film deviation is about % of that of the conventional method, but at IPa or less, the film formation rate decreases considerably, and 0. At lPa, almost no thin film is formed. This is considered to be because at low gas pressure, scattering of sputtered particles by the sputtered gas disappears, so that no sputtered particles enter the substrate. When the temperature exceeds ZPai degree, scattering by the spanner gas increases and a thin film is formed.

Next, the results of the analysis of the structure of the thin film are shown in FIG. It can be seen that the thin film (indicated by . or ▲) produced by the rice pressing method has a composition with less Ba and Cu than the oxide targut, and this tendency becomes more pronounced as the gas pressure decreases. In contrast, the thin film produced by the method of the present invention (indicated by ● or Δ) has a composition almost similar to that of the oxide target, regardless of the gas pressure. These phenomena occur when high-energy oxygen ions or atoms enter the thin film and cause Ba,
This can be explained as being due to selective re-sputtering of Cu. That is, in the conventional method, oxygen particles sputtered in the form of negative ions from an oxide target are transported by an electric field and are incident with high energy into the molecule being formed.
Ba and Cu are selectively sputtered to cause a change in composition, but as the gas pressure decreases, scattering by the sputtering gas decreases, the energy when reaching the substrate increases, and the number of particles increases, resulting in a larger change in composition. . In addition, in the uninvented method, the path of high-energy particles from the erosion region of the oxide target toward the substrate is blocked by the mask l, so that the only oxygen that enters the substrate is that which has been scattered by spatter gas on the way, and the number of Both energy and energy are greatly reduced compared to the conventional method without a mask, resulting in less compositional changes. Even with the conventional method, a thin film with Y:Ba:Cu=1:2:3 can be fabricated by increasing Ba and Cu in the oxide target in advance to compensate for the shortage of Ba and Cu, but in this case, the oxidation Determining the optimal composition for object targets requires repeated trial-and-error experiments, which is very time-consuming.

Among the thin films produced by the conventional method using an oxide target with a large amount of Cu (Y:Ba:Cu==1:2:6),
The one whose composition was closest to Y:Ba:Cu=1:2:3 was selected and compared with the characteristics of the thin film produced by the method of the present invention. FIG. 5 shows the change in resistance with temperature. The thin film according to the present invention has a critical temperature (Tc) as high as 89 K as shown in curve [5] (gas pressure 5 P).
In the conventional method, as shown in the curved edge 7, the resistance was as low as 53K, and the absolute value of the resistance was also high. By annealing in oxygen at a temperature of 900°C for 1 hour, Tc is 77K'! as shown in curve 6! However, it is not as high as that of the thin film according to the present invention. Also, the critical current at 77K'4C (J
When c) was measured, the thin film according to the present invention showed a high value of 25 x 10' A/vrtl even in an as-deposited state. This value was further increased to 380X10'! by performing low-temperature annealing at 500℃ for 1 hour in oxygen! VOrt
It is improved by l i. This is a sufficient value when considering device applications. As described above, in the method according to the present invention, high quality YB can be produced using only a low temperature process of 600°C or less.
A CO thin film can be produced. The reason for this is that in the method of the present invention, the i! This is thought to be because the incidence on the A film is reduced, resulting in the formation of an excellent crystalline thin film with few lattice defects.

In the above examples, the production of YBCOilg was described, but one in which Y was replaced with another rare earth element, B1-Sr
The invention is also effective in producing superconducting oxide thin films containing copper, such as -Ca-Cu-Q series and T-6-Ba-Ca-Cu-0 series. Also, instead of RF magnetron sputtering, DC
Needless to say, magnetron sputtering may also be used.

In the example described above, the mask was placed so as to intersect all the spatial regions formed by the linear trajectory of the subactor particles from the erosion region of the oxide target to the superconducting oxide thin film of the substrate. Considering that there are differences in the degree of sputtering within the erosion region, and that the incident density of high-energy particles decreases as the substrate moves away from directly above the erosion region8, it is important to note that thin film materials (to what extent selective re-sputtering occurs) Depending on the position of the substrate, it may not necessarily be necessary to block all of the above-mentioned spatial region.

Furthermore, the shape of the mask for blocking high-energy oxygen ions is not limited to those described in Examples 1 and 2, and
The cylindrical one shown in the figure and the combination of concentric rings and disks shown in Fig. 7. A combination of rectangular plates shown in FIG. 8 and a combination of corrugated rings shown in FIG. 9 can also be suitably used.

〔Effect of the invention〕

[Effects of the Invention] 1) In the method for manufacturing a superconducting oxide thin film containing copper by planar magnetron spacing and tarring, the erosion region of the superconducting oxide target, the oxide thin film on the substrate, and the two-layered region are Sputtering is performed by providing a mask that intersects at least a part of the spatial region formed by the linear trajectory of the sputtered particles starting from the starting point and reaching the oxide thin film.
The amount of elementary ions incident on the substrate is reduced, the chemical composition of the crystal becomes stoichiometric, or lattice defects are reduced, making it possible to produce a superconducting oxide thin film with excellent superconducting properties. 2) In a method for producing a zinc oxide thin film by planar magnetron sputtering, the erosion region of the oxide target, the zinc oxide thin film on the substrate, and the zinc oxide Ny. Since sputtering is performed by providing a mask that intersects at least a part of the spatial region formed by the linear trajectory of the sputter particles leading to the sputtering, the mask reduces the amount of high-energy oxygen ions incident on the substrate and improves the crystal orientation. It becomes possible to produce a zinc oxide thin film with improved homogeneity and excellent piezoelectric properties.

[Brief explanation of drawings]

Figure 1 shows the oxide target and mask used in the method for manufacturing zinc oxide thin films. FIG. 2 is a perspective view showing the arrangement of the substrates, and an oxide target related to the method for manufacturing a superconducting oxide thin film. A perspective view showing the arrangement of the mask and the substrate; FIG. 3 is a diagram showing the dependence of film speed on gas pressure in a method for producing a superconducting oxide thin film;
Fig. 4 is a diagram showing the dependence of stoichiometry on gas pressure according to the method for manufacturing superconducting oxide thin films, and Fig. 5 is a diagram showing the dependence of stoichiometry on gas pressure according to the method for producing superconducting oxide thin films.
Diagram showing the resistance-temperature characteristics of ultra-tS sensitized *thin films according to the method for manufacturing compound thin films compared with conventional ones, Figure 6 is a cross-sectional view showing different embodiments of the mask, Figures 7 and 8 , FIG. 9 shows further different embodiments of the mask, FIG. , FIG. 9 is a cross-sectional view. l...Oxide target area, 2...Erosion area, Fig. 2. Force FL (Pa) 45l

Claims (1)

[Claims] 1) A method for producing a superconducting oxide thin film containing copper by planar magnetron sputtering, in which an erosion region of a superconducting oxide target, an oxide thin film on a substrate, and oxidation starting from the erosion region are performed. 1. A method for producing a superconducting oxide thin film, which comprises performing sputtering by providing a mask that intersects at least a portion of a spatial region formed by a linear trajectory of sputtered particles leading to a thin film. 2) In a method for producing a zinc oxide thin film by planar magnetron sputtering, an erosion region of an oxide target, a zinc oxide thin film on a substrate, and a linear trajectory of sputtered particles starting from the erosion region and reaching the zinc oxide thin film. 1. A method for producing a zinc oxide thin film, which comprises performing sputtering by providing a mask that intersects at least a portion of a spatial region formed by the above.