JP2002012965A - Method and target for laser vapor deposition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vapor deposition method with laser, which can form a uniform film easily on a substrate with a large area, and to provide a target used for the vapor deposition method with the laser. SOLUTION: The vapor deposition method with laser comprises irradiating a laser light 10 to a target 1 and depositing substances 2 scattered from the target 1 on a substrate 20. The surface of the target 1 has at least either of a curvature or a crossing gradient along a crossing direction to an irradiating direction of the laser light 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser deposition method and a laser deposition target, and more specifically, to a laser deposition method and a laser deposition target.
The present invention relates to a laser vapor deposition method for irradiating a target with laser light and depositing substances scattered from the target on a substrate, and a target used for the laser vapor deposition method.

[0002]

2. Description of the Related Art In a laser vapor deposition method, a substance 2 (atoms and / or molecules) is scattered from a target 1 as shown in FIG. For this reason, the film is formed on the substrate 20 by condensing the laser 10 on the target 1 using an optical system such as a lens to have an energy density equal to or higher than a threshold.

In particular, in the case of using an excimer laser as a laser, there is almost no difference between the composition of a target and the composition of a film to be formed. Since the laser source is outside the vacuum chamber, the atmosphere in the vacuum chamber can be freely set. When the deposition rate is changed by other gas phase methods (sputtering, MBE (Molecular Beam E
pitaxy), etc.). For this reason,
Such a laser deposition method has been adopted by many research institutions since the discovery of the oxide superconducting material as a technique for forming a multi-component oxide superconducting thin film (for example, S. Witan
achchi et al., Applied Physics Letters vol.53, p.2
34 (1988)).

[0004]

In the laser vapor deposition method, as described above, the laser beam 10 is focused on the target 1 using an optical system.
Becomes very small. In addition, since the flying direction of the scattered particles 2 in this laser vapor deposition method is the normal direction of the surface of the target 1, the film can be formed only on a limited area on the substrate 20. Was narrowly limited. Therefore,
When forming a film on a large-sized substrate 20,
For example, a method of disposing the substrate 20 in parallel (off-axis arrangement) with respect to the trajectory of the particles 2 scattered from the target 1 and rotating the substrate 20 (for example, Japanese Patent No. 2817299)
And a method of displacing the substrate 20 during the film formation (for example, Japanese Patent Laid-Open No. 4-45263).

It is therefore an object of the present invention to provide a laser vapor deposition method and a laser vapor deposition target capable of easily forming a uniform film on a substrate having a large area.

[0006]

According to a laser vapor deposition method of the present invention, a target is irradiated with laser light, and a substance scattered from the target is deposited on a substrate. Characterized by having at least one of a curvature and an intersecting inclination along a direction intersecting with.

According to the laser vapor deposition method of the present invention, the direction of scattering of a substance from a target can be greatly expanded outward by a curvature or inclination of the surface of the target as compared with a case where the target surface is flat. This makes it possible to deposit the scattered substance on the substrate in a wide range, so that a uniform thin film can be formed on a large substrate.

In the above-mentioned laser vapor deposition method, preferably, the direction intersecting the laser light irradiation direction is a direction orthogonal to the laser light irradiation direction.

With this arrangement, when the laser light is irradiated on the target surface in a linear shape, the focal lengths of the laser irradiation parts can be made equal.

[0010] In the above laser vapor deposition method, preferably, the laser irradiating portion irradiated with the laser beam on the target surface has a minor axis and a major axis, and the surface of the target has a curvature along the major axis direction and a slope having a crossing slope. It has at least one.

As a result, the substance can be scattered while the width in the major axis direction of the laser irradiation portion is expanded outward, and a uniform thin film can be formed on a large substrate.

Preferably, in the above laser vapor deposition method, the laser light is any of the following a and b.

A: Excimer laser light using, as an excitation gas, one of a mixed gas containing krypton and fluorine, a mixed gas containing xenon and chlorine, a mixed gas containing argon and fluorine, and a mixed gas containing fluorine gas. b: Double wave, third wave, or fourth wave of YAG laser light By irradiating such a laser light to the target, the substance can be scattered well from the target.

In the above-mentioned laser vapor deposition method, preferably, the laser irradiation part is linear. This makes it possible to uniformly deposit the scattered material from the target on a large substrate in a wide range in the linear irradiation section.

A target for laser deposition according to one aspect of the present invention is a target for scattering a substance by laser irradiation and depositing the substance on a substrate, and has a plate-like shape and a curvature and an intersection with the surface. It has at least one of the slopes.

By using such a target, it becomes possible to deposit a scattered substance from the target when the target is irradiated with laser light in a wide range on the substrate as described above. However, a uniform thin film can be formed.

A target for laser evaporation according to another aspect of the present invention is a target for depositing a substance on a substrate by scattering a substance by irradiating a laser beam, and has a barrel-shaped outer shape.

By having such a shape, it becomes possible to vapor-deposit a substance scattered from the target when a laser beam is irradiated on the surface of the target over a wide range, so that even a large substrate can be deposited. A uniform thin film can be formed.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view for explaining a laser vapor deposition method according to one embodiment of the present invention. Referring to FIG. 1, in the laser deposition method of the present embodiment, first, target 1 is arranged. A laser beam 10 is condensed, for example, linearly on the surface of the target 1 by an optical system (not shown) such as a lens and irradiated. This irradiation
This is performed at an energy density equal to or higher than a threshold value for scattering substances 2 such as atoms and / or molecules from the surface of the target 1. As a result, the substance 2 scatters from the laser irradiation unit 10A of the target 1 in a direction substantially normal to the surface of the target 1, and the scattered substance 2 is deposited on the substrate 20 to form a film.

In the present embodiment, the surface of the target 1 irradiated with the laser beam 10 has a curvature. As a result, the substance 2 scattered from the target 1 is irradiated onto the irradiation unit 1
It is scattered so as to spread outward from 0A and is deposited on the surface of the substrate 20.

In this embodiment, since the surface of the target 1 has a curvature, the material scattered from the target 1 is deposited on the surface of the substrate 20 so as to spread outward, so that the scattered material can be spread over a wide area. It becomes possible to vapor-deposit on the substrate 20, and a uniform thin film can be formed even on a large substrate 20.

During the above-mentioned laser deposition, the substrate 20 may be moved in the direction of arrow D. Thereby, the substrate 20
, A uniform thin film can be formed continuously in the direction of arrow D.

The target 1 may also be moved in the direction of arrow E during the laser deposition. Thereby, the position of the laser irradiation part 10A on the surface of the target 1 can be changed, and the excessive shaving of the target 1 by the laser irradiation can be prevented.

Referring to FIG. 2, it is preferable that the irradiation direction A1 of laser beam 10 irradiated on target 1 is perpendicular to the line direction of linear laser irradiation section 10A. If the laser beam 10 is radiated at an acute angle or parallel to the line direction of the laser irradiation unit 10A as shown by a dotted line, the focal lengths are different between the two ends S1 and S2 of the laser irradiation unit 10A. For this reason, it becomes difficult to adjust the energy density of the laser 10 irradiating the target 1.

On the other hand, when the laser 10 is irradiated so as to be orthogonal to the line direction of the linear laser irradiation section 10A, the focal lengths at both ends S1 and S2 become the same, and the target 1 is irradiated. The energy density of the laser 10 can be easily adjusted, and a uniform thin film can be easily formed.

Also, the case where the surface has a curvature as the target 1 has been described, but as shown in FIG.
It may have a plurality of shapes where the slopes intersect (hereinafter referred to as a mountain-cut shape).

When the target 1 is moved in the direction of arrow E as shown in FIGS. 1 and 3, it is preferable that the cross section of the target 1 be continuous in the direction of arrow E.
Thus, even when the target 1 moves in the direction of the arrow E, the shape of the laser irradiation unit 10A does not change, so that a uniform thin film can be formed continuously.

Even in the case of such a mountain-cut shape, since the substance scatters from the target 1 in the direction normal to the inclined surface, the scattered substance 2 can be deposited on the substrate 20 in a wide range, A uniform thin film can be formed even on a large substrate 20.

The larger the number of the ridges in the laser irradiation section 10A, the more the scattered substance 2 can be scattered more uniformly.

As shown in FIG. 4, the surface of the target 1 on which the laser is irradiated may have a shape in which a plurality of convex portions 1B having a curvature are arranged. Also, this convex portion 1B
It may be continuous in the longitudinal direction as shown in FIG.
And a large number of them may be arranged regularly or irregularly.

As shown in FIG. 7, the surface of the target 1 on which the laser beam is irradiated may have a shape in which a plurality of concave portions 1C having a curvature are arranged. This recess 1C is shown in FIG.
May be continuous in the longitudinal direction, as shown in FIG. 9, or may be arranged regularly or irregularly as shown in FIG.

The target 1 is not limited to a plate-like target, but may have a barrel-shaped outer shape as shown in FIG. In this case, it is preferable that the target 1 be rotated in the direction of arrow E about the axis during laser deposition.

Further, as shown in FIG.
An imaginary line (CC line) orthogonal to the BB line connecting both ends S1 and S2 of A and passing through the center of the laser irradiation unit 10A.
On the other hand, it is preferable that the surface shape of the target 1 in the laser irradiation unit 10A has a line symmetry. As a result, a thin film can be uniformly formed on the right and left sides of the virtual line (CC line) of the substrate 20 in the drawing.

As the material of the target 1, a superconducting material such as bismuth or holmium can be used in addition to yttrium.

[0036]

Embodiments of the present invention will be described below.

COMPARATIVE EXAMPLE As shown in FIG. 14, a film was formed by a laser deposition method using a target 1 having a flat surface. Table 1 shows the conditions of the laser deposition method.

[0038]

[Table 1]

The film formation by the laser vapor deposition method was performed while moving the substrate 20 in FIG. The thickness distribution of the YBCO thin film formed on the substrate 20 was measured at 25 points shown in FIG. Table 2 shows the measurement results of the film thickness distribution. In Table 2, the positions where the numerical values of the respective film thicknesses are described correspond to the positions of the respective numbers described in the substrate 20 in FIG. That is, the film thickness value (0.42) in the upper left of Table 2 corresponds to the film thickness at the position of "1" in the upper left of FIG.

[0040]

[Table 2]

From the results shown in Table 2, it can be seen that the thickness difference of the YBCO thin film formed on the substrate 20 is large at both ends in the direction orthogonal to the moving direction (the direction of arrow D).

Example 1 As shown in FIG. 1, a film was formed under the same conditions as in the comparative example using a target 1 having a specific curvature R = 200 mm according to the present invention. Table 3 shows the film forming conditions. All conditions were the same as in the above comparative example, except that the target 1 having a curvature was used.

[0043]

[Table 3]

In this laser deposition method, the film was formed while moving the substrate 20 in the direction of arrow D. The thickness distribution of the YBCO thin film formed on the substrate 20 was measured at each point shown in FIG. Table 4 shows the results.

[0045]

[Table 4]

From the results shown in Table 4, it can be seen that the difference in film thickness is smaller than that in the comparative example. From this, it is understood that the uniformity of the film thickness is greatly improved in the present example as compared with the comparative example.

Example 2 As shown in FIG. 1, a film was formed under the same conditions as in the comparative example, using a target 1 having a specific curvature R = 100 mm according to the present invention. Table 5 shows the film forming conditions. All conditions were the same as in the above comparative example, except that the target 1 having a curvature was used.

[0048]

[Table 5]

In this laser deposition method, the film was formed while moving the substrate 20 in the direction of arrow D. The thickness distribution of the YBCO thin film formed on the substrate 20 was measured at each point shown in FIG. Table 6 shows the results.

[0050]

[Table 6]

From the results shown in Table 6, the uniformity of the film thickness was greatly improved as compared with the comparative example, and the uniformity was further improved as compared with the target 1 having the curvature R of 200 mm in Example 1. You can see that it is.

Example 3 As shown in FIG. 3, a target 1 having a mountain-shaped surface according to the present invention was used.
Film formation was performed under the same conditions as in the comparative example. Table 7 shows the film forming conditions. All conditions were the same as in the above comparative example except that the target 1 having a mountain-cut shape was used. As shown in FIG. 13, the target 1 used had a cross section in which the pitch (width) of the mountain cut was 10 mm and the height was 5 mm.

[0053]

[Table 7]

At the time of this laser deposition, film formation was performed while moving the substrate 20 in the same manner as in the comparative example. The thickness distribution of the YBCO thin film formed on the substrate 20 was measured at each point shown in FIG. Table 8 shows the results.

[0055]

[Table 8]

From the results shown in Table 8, the uniformity of the film thickness was greatly improved as compared with the comparative example.
It can be seen that the film thickness uniformity almost equivalent to that when the 00 mm curved target is used is obtained.

The embodiments and examples disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0058]

As described above, according to the laser vapor deposition method of the present invention, the direction of scattering of a substance from a target is made more outward than when the target surface is flat by the curvature or inclination of the surface of the target. Can be greatly expanded. This makes it possible to deposit the scattered substance on the substrate in a wide range, so that a uniform thin film can be formed on a large substrate.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a laser deposition method using a target having a curvature according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a laser irradiation direction.

FIG. 3 is a perspective view showing a laser deposition method using a mountain-shaped target according to another embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a configuration of a target provided with a plurality of convex portions having a curvature.

FIG. 5 is a perspective view showing a configuration of a target having a shape in which convex portions having a curvature are continuous in a longitudinal direction.

FIG. 6 is a perspective view showing a target configuration in which a plurality of convex portions having a curvature are arranged regularly or irregularly.

FIG. 7 is a cross-sectional view showing a configuration of a target provided with a plurality of concave portions having a curvature.

FIG. 8 is a perspective view showing a configuration of a target in which a concave portion having a curvature has a shape continuous in a longitudinal direction.

FIG. 9 is a perspective view showing a configuration of a target in which a plurality of concave portions having a curvature are arranged regularly or irregularly.

FIG. 10 is a perspective view showing a laser vapor deposition method when a target having a barrel-shaped outer shape is used.

FIG. 11 is a diagram for explaining a shape of a target in a laser irradiation section.

FIG. 12 is a diagram showing film thickness measurement points of a thin film formed on a substrate.

FIG. 13 is a cross-sectional view for explaining a mountain-cut shape used in a third embodiment.

FIG. 14 is a perspective view showing a laser deposition method when a target having a flat surface is used.

[Explanation of symbols]

1 target, 2 scattering substances, 10 laser light, 10
A Laser irradiation part, 20 substrates.

Claims (6)

[Claims] In a vapor deposition method of irradiating a target with laser light and depositing a substance scattered from the target on a substrate, a surface of the target has a curvature along a direction intersecting a direction of irradiation of the laser light. And at least one of intersecting slopes. 2. The laser vapor deposition method according to claim 1, wherein the direction intersecting with the laser light irradiation direction is a direction orthogonal to the laser light irradiation direction. 3. A laser irradiating unit that irradiates the surface of the target with laser light has a minor axis and a major axis, and the surface of the target has at least one of a curvature and a crossing inclination along the major axis direction. 3. The method according to claim 1, wherein
4. The laser deposition method according to 1. 4. The laser vapor deposition method according to claim 1, wherein said laser irradiation section is linear. 5. A laser vapor deposition target for scattering a substance by being irradiated with a laser beam and depositing the substance on a substrate, wherein the target has a plate shape and has at least one of a curvature and a crossing slope on the surface. Laser deposition target. 6. A laser vapor deposition target for scattering a substance by laser beam irradiation and depositing the substance on a substrate, wherein the laser vapor deposition target has a barrel-shaped outer shape.