JPH1060629A - Laser vapor deposition film forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form thin film having a uniform compsn. and film thickness on a substrate, at the time of irradiating a target with converged laser light and depositing target substance thin film on a substrate, by deflecting the direction of the normal in the plane of the target from the rotating direction of the target. SOLUTION: A target fixing stand 6 rotating in the direction of the arrow A is mounted with a target 1, and a substrate 2 is provided opposite to the target 1 and is rotated in the direction of the arrow B. At this time, the direction of the normal of the surface to be irradiated with laser light 5 of the target 1 is deflected from the direction of the rotary shaft of the target 1 so that the rotary shaft of the target 1 and the rotary shaft of the substrate 2 are parallel to each other and deviated from each other. In this way, at the time of irradiating the substrate 2 with a plasma plume 3, thin film of a large area uniform in film thickness can be formed on the substrate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser deposition apparatus for forming a thin film having a uniform thickness by a laser deposition method.

[0002]

2. Description of the Related Art Since the formation of several types of thin films by a ruby laser was reported in 1965, thin films have been formed using various lasers such as an Nd: YAG laser and a CO ₂ laser. Since then, the power of laser oscillators has been improved and the wavelength has been shortened, the materials that can be thinned have been widened, and the quality of the thin films has also been improved. In particular, as a method for forming an LnBa ₂ Cu ₃ O _x oxide superconductor (Ln: Y and lanthanide element) thin film having Tc90K discovered in 1987, a laser vapor deposition method capable of vapor deposition under a high oxygen pressure attracts attention. A laser vapor deposition apparatus using a laser vapor deposition method has been evaluated as an optimal apparatus for forming an oxide thin film because it is easy to realize a high Tc. Further, in recent years, a laser vapor deposition apparatus has been used for forming a ferroelectric thin film because of its simplicity.

FIG. 4 is a schematic perspective view showing a part of a conventional laser deposition apparatus. As shown in the figure, a target 1 is attached to a target fixing base 4 that rotates in the direction of arrow A, and a substrate 2 is provided so as to face the target 1. The substrate 2 has an axis coinciding with the rotation axis of the target fixing base 4. The substrate 2 is rotated in the direction of arrow B as a rotation axis, and the substrate 2 is heated by a substrate heater (not shown).

In this laser deposition apparatus, when a target 1 is irradiated with a laser beam 5 such as an excimer laser beam, a part of the target 1 irradiated with the laser beam 5 is excited by the laser beam 5 and a target material is irradiated. Is turned into plasma in oxygen gas, and the target material is deposited on the substrate 2, whereby a thin film is formed on the substrate 2.

In such a laser deposition film forming apparatus, deposition can be performed under a high oxygen pressure, and if a laser beam 5 having a certain energy or more is irradiated, the composition of the thin film deviates from the composition of the target 1. It has the advantage of not being.

However, when a thin film is formed under a high oxygen pressure by the laser deposition apparatus shown in FIG.
The deposition rate is high immediately above the substrate 2 where the plasma plume 3 has reached, and the deposition rate rapidly decreases as the distance from the central axis of the plasma plume 3 increases. For this reason, when the plasma plume 3 is irradiated to the center of rotation of the substrate 2, the film forming rate at the central portion of the substrate 2 is high, and the film forming speed at the peripheral portion of the substrate 2 is low. As shown in the figure, a thick thin film is formed at the center of the substrate 2. On the other hand, when the plasma plume 3 is irradiated at a position slightly away from the rotation center of the substrate 2, as shown in FIG. 6, the center of the substrate 2 is dented, and the distance at which the plasma plume 3 is irradiated is high. A thin film having a donut-shaped film thickness profile is formed. 5 and 6, the vertical axis represents the thickness of the thin film, and the horizontal axis represents the distance from the rotation center of the substrate 2. As described above, depending on the irradiation position of the plasma plume 3, a large difference in film thickness occurs between the formed thin films.

To solve this problem, a laser beam 5
A reflector is provided between a condenser lens for condensing light and the target 1, and by slightly changing the angle of the reflector, the laser beam 5 scans on the target 1 and reaches the substrate 2. A method of changing the position of the plasma plume 3 is adopted. In this case, a thin film having a uniform thickness and a large area can be formed.

[0008]

However, when the laser beam 5 is scanned by the reflection plate, the following problems newly arise. That is, first, since the distance from the condenser lens to the position on the target 1 where the laser light 5 is irradiated is changed by the scanning of the laser light 5, the target 1 is irradiated with the defocused laser light 5. Therefore, variations in the composition, the size of the plasma plume 3 and the like occur. Second, since the number of reflections of the laser light 5 increases, in order to maintain the composition of the thin film formed on the substrate 2, high energy enough to guarantee the attenuation due to the reflection of the laser light 5 is required. It is necessary to irradiate the laser beam 5 which has.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a laser vapor deposition apparatus capable of forming a thin film having a uniform composition and thickness without increasing the energy of laser light. The purpose is to provide.

[0010]

In order to achieve this object, in the present invention, a laser beam is deposited by irradiating a converged laser beam to a target to convert the target material into plasma and depositing a thin film of the target material on a substrate. In the film forming apparatus, the direction of the normal to the plane of the target is deflected from the direction of the rotation axis of the target.

[0011]

FIG. 1 is a schematic perspective view showing a part of a laser vapor deposition apparatus according to the present invention. As shown in the figure, the target 1 is mounted on the target fixing base 6, and the target 1 mounting surface of the target fixing base 6, and the normal direction of the plane of the target 1, that is, the normal direction of the surface on which the laser beam 5 is irradiated, It is deflected from the direction of the rotation axis of the target 1, and the rotation axis of the target 1 and the substrate 2
Are parallel to each other, and the rotation axis of the target 1 and the rotation axis of the substrate 2 are displaced from each other.

In this laser vapor deposition apparatus, the irradiation direction of the plasma plume 3 is perpendicular to the plane of the target 1, so that the direction of the normal to the plane of the target 1, that is, the direction of the rotation axis of the rotating target 1 The plasma plume 3 is irradiated in a direction having a certain angle.
For this reason, in the state shown in FIG. 1, when the laser beam 5 is applied to the vicinity of the rotation center of the target 1, the plasma plume 3 is applied to the lower part of the substrate 2 in FIG. In the state shown in FIG. 2 in which the table 6 and the target 1 are rotated by 180 degrees, when the laser beam 5 is applied to the vicinity of the rotation center of the target 1, the plasma plume 3 is applied to the upper part of the substrate 2 in FIG. As described above, while the target 1 makes one rotation, the scanning position of the plasma plume 3 is such that the extension of the rotation axis of the target 1 is
Draw a circle centered on the point of intersection. Therefore, by irradiating the substrate 2 with the plasma plume 3 while rotating the target 1 and the substrate 2, a thin film having a uniform thickness and a large area can be formed on the substrate 2. In this case, if the rotation axis of the substrate 2 is far from the center of the circle, the plasma plume 3 can be irradiated to a wider range.

In such a laser vapor deposition apparatus, when the laser beam 5 is irradiated near the center of rotation of the target 1, the distance between the condenser lens and the irradiation position of the laser beam 5 hardly changes. Since the shifted laser beam 5 is not irradiated on the target 1, there is no variation in the composition, the size of the plasma plume 3 and the like. Further, since a thin film having a uniform composition and thickness and a large area can be formed without using a reflector, it is not necessary to irradiate the laser beam 5 having high energy, and it is clear that there is no energy loss. It is.

FIG. 3 is a schematic perspective view showing a part of a laser deposition apparatus according to the present invention. As shown in the figure, the rotation axis of the substrate 2 is inclined with respect to the rotation axis of the target 1.

In this laser vapor deposition apparatus, a film having a further improved uniformity of the film thickness can be formed on the substrate 2 by keeping a portion of the substrate 2 where the deposition rate is high away from the target 1. it can.

In the above embodiment, the substrate 2
The direction of rotation of the target 1 and the direction of rotation of the target 1 are opposite. However, even if the direction of rotation of the substrate 2 and the direction of rotation of the target 1 are the same, the number of rotations of the target 1 and the number of rotations of the substrate 2 are the same. Unless the ratio between the rotation speed of the target 1 and the rotation speed of the substrate 2 becomes a small natural number ratio,
The uniformity of the film thickness formed on the substrate 2 is improved.

[0017]

In the laser deposition apparatus according to the present invention, it is not necessary to use a reflection plate, so that it is not necessary to increase the energy of the laser light, and the target is irradiated with the defocused laser light. Therefore, a thin film having a uniform composition can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a part of a laser deposition apparatus according to the present invention.

FIG. 2 is an explanatory view of the operation of the laser vapor deposition apparatus shown in FIG.

FIG. 3 is a schematic perspective view showing a part of another laser vapor deposition apparatus according to the present invention.

FIG. 4 is a schematic perspective view showing a part of a conventional laser deposition apparatus.

FIG. 5 is a graph showing the thickness of a thin film formed by the laser deposition apparatus shown in FIG.

FIG. 6 is a graph showing the thickness of a thin film formed by the laser vapor deposition apparatus shown in FIG.

[Explanation of symbols]

 1. Target 2. Substrate 3. Plasma plume

Claims (1)

[Claims] 1. A laser deposition apparatus for irradiating a target with a converged laser beam to convert the target material into plasma and depositing a thin film of the target material on a substrate, wherein the normal direction of a plane of the target is the target. A laser deposition apparatus which is deflected from the direction of the rotation axis.