JPH0441666A - Method for manufacturing thin films using laser evaporation method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing a thin film by laser vapor deposition. More specifically, the present invention relates to a method of producing a high-quality thin film using a laser vapor deposition method.

BACKGROUND OF THE INVENTION Various methods are used to produce thin films, but the laser deposition method has advantages such as easy control of composition and fast film formation rate. Furthermore, because it does not require a negative electromagnetic field, it is considered to be a suitable method for producing high-quality thin films.

Conventionally, when producing thin films using laser evaporation, the substrate and target are placed inside a deposition chamber that can be evacuated to a high vacuum and any atmospheric gas can be introduced, and the laser device is placed outside the deposition chamber. The emitted laser light was guided by optical means and irradiated onto the target.

Problems to be Solved by the Invention When producing thin films using laser vapor deposition, the film is formed at the tip of a plasma state called a wax-like plume that is generated when a target is irradiated with laser light. This is because there are many oxidized and active film-forming particles at the tip of the plume, and a thin film with good properties can be obtained by forming a film at this part.

On the other hand, in general, in the laser vapor deposition method, the area irradiated with the laser beam is limited in size due to limitations of the apparatus, and the area of the target irradiated with the laser beam is a small portion of the area of the entire target. As a result, the plume is also small, especially the tip of the plume, which is extremely small. The distribution of membrane quality was large and the distribution of membrane quality was also remarkable.

Therefore, the purpose of the present invention is to solve the problem of non-uniform film formation in a small area, which is a disadvantage of laser evaporation, and to provide a method for producing a thin film with a larger area than usual, with a small distribution of film thickness and film quality, using laser evaporation. It's about doing.

Means for Solving the Problems According to the present invention, a method for producing a thin film by a laser evaporation method in which a target is irradiated with pulsed laser light and a thin film is deposited on a substrate placed opposite to the target is provided. There is provided a method for producing a thin film, characterized in that vapor deposition is performed by displacing the substrate in synchronization with irradiation with pulsed laser light so that the thin film is mainly deposited at positions determined by random numbers on the surface of the substrate.

The main feature of the method of the present invention is that vapor deposition is performed by displacing the substrate so that the thin film is mainly deposited at positions determined by random numbers on the substrate in the film forming chamber. This displacement of the substrate is performed in synchronization with the irradiation of pulsed laser light.

In the laser vapor deposition method, plasma, which is a collection of active film-forming particles called a plume, is generated above the position of the target that is irradiated with laser light. When a substrate is placed in a position where this plume contacts, a thin film is mainly deposited on the substrate near the tip of the plume.

Therefore, with the method of the present invention, it is possible to form a uniform thin film over a large area.

In the method of the present invention, the position where the substrate should touch the tip of the plume is determined using random numbers, and the substrate is moved so that the plume hits that position. Specifically, the surface of the substrate is divided into a grid pattern, each part is numbered, and a random number generator or the like is used to generate random numbers to determine the position where the plume hits. In the method of the present invention, the position of the plume is not moved in a specific order, but is moved randomly using random numbers, so a more homogeneous thin film can be produced.

In the method of the present invention, for example, a substrate is mounted on an XY stage that is displaced in accordance with the random number described above and moved. In the method of the present invention, only the substrate is displaced and the optical path of the laser beam is constant. Therefore, unlike changing the laser irradiation position by waving a laser beam, the film forming conditions do not change depending on the position of the substrate.

Further, in the method of the present invention, it is also preferable that the planar shape of the target is circular, the target is rotated, and the peripheral part of the target is irradiated with laser light. This is because if the same part of the target is hit by the laser beam, only that part of the target will be consumed and dented, changing the direction of the plume.

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The following disclosure is merely an example of the present invention and does not limit the technical scope of the present invention in any way.

Embodiment FIG. 1 shows an example of a laser vapor deposition apparatus for carrying out the method of the present invention. In the laser evaporation apparatus shown in FIG.
The laser light generated by the laser beam passing through the condensing lens 9 enters the laser entrance window 7 of the chamber 1 and irradiates the raw material target 5 mounted on the turntable 11 inside the chamber 1 . The turnpull 11 can be rotated by a motor 14 at any rotational speed. The inside of the chamber 1 can be evacuated to a high vacuum, and the substrate 2 is fixed to a substrate holder 3 mounted on an XY stage 12 so as to face a target 5. A heater 4 for heating the substrate 2 is provided inside the substrate boulder 3. Further, a nozzle 6 for supplying a gas containing oxygen into the chamber 1 is provided.

In the device of this embodiment, the laser device 10 oscillates pulsed laser light. In response to this pulse, a control device 13 equipped with a random number generator sends a control signal to the XY stage 12. The XY stage 12 displaces the substrate 2 for each pulse based on this control signal, so that the pulsed laser beam hits the target 5.
The tip of the plume generated when the beam is irradiated is brought into contact with a portion of the substrate determined by a random number for each pulse.

Using the above laser evaporation apparatus and the method of the present invention, YI
A Ba2CUsOt-x oxide superconducting thin film was fabricated.

For the substrate 2, an MgO single crystal substrate and a 5rTi03 single crystal substrate were used, and the substrate temperature was 650°C to 750°C. Target 5 is Y1Ba2CL1 with a diameter of 2 cm.
A sintered body of 30t-x was used. Further, the distance between the substrate 2 and the target 5 was 7 cm. Inside of chamber 1
After exhausting to ×1 O-6 Torr, oxygen gas was introduced.
00mTorr.

The laser uses an excimer laser with a wavelength of 193 nm.
The laser output was 3.5 J/cnf, the laser beam irradiation area was 2X4u+n2, and the pulse frequency was 5Hz.

The substrate 2 on the XY stage 12 was displaced by the control device 13 based on random numbers, so that the plume scanned an area of 3×3 crl on the substrate 2. Further, the target 5 was rotated at 1.5/sec.

Under the above conditions, open film formation was performed for 30 minutes, and the film thickness distribution and superconducting properties of the obtained oxide superconducting thin film were measured.

As a result, the film thickness distribution of the oxide superconducting thin film produced by the method of the present invention was ±10% in the range of 35×35 mm 2 . On the other hand, with the other film forming conditions being the same, the film thickness distribution in the case of the conventional method in which the plume remains in contact with one point on the substrate was ±10% in the range of 1010 x 10''.In the method of the present invention Table 1 shows the measurement results of the critical temperature and film thickness of the produced oxide superconducting thin film.

According to the present invention as described in detail in Table 1, it is possible to fabricate a thin film with a larger area and a smaller thickness distribution than before. This is an effect unique to the method of the present invention in which the film is formed while moving the substrate so that the plume hits a position determined by a random number on the substrate.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an example of a laser deposition apparatus that implements the method of the present invention. [Main reference numbers] 1... Chamber 2... Substrate 3... Substrate holder 4... Heater 5... Target 6... Nozzle 7... Entrance window 8... Mirror 9... ...Condensing lens 10...Laser device 11...Turntable, 12...XY stage, 13...Control device

Claims (1)

[Claims] In a method of producing a thin film by a laser evaporation method in which a target is irradiated with pulsed laser light and a thin film is deposited on a substrate placed opposite to the target,
A method for producing a thin film, characterized in that vapor deposition is performed by displacing the substrate in synchronization with irradiation with pulsed laser light so that the thin film is deposited mainly at positions determined by random numbers on the surface of the substrate.