JPH0250959A - Method and apparatus for forming thin film of rare earth metal - Google Patents

Abstract

PURPOSE:To form a required high degree of vacuum in a short time by discharging an active metal from an auxiliary target in a side position to form a high vacuum, impressing a voltage on the main cathode, and forming a thin film of rare earth metal on the surface of a substrate. CONSTITUTION:A rare earth metal target 2 and a substrate 5 are disposed in a vacuum chamber 1 in a manner to be opposed to each other, and an active metal auxiliary target 6 is disposed in a position beside the substrate 5. The inside of the chamber 1 is evacuated to regulate the pressure inside the chamber 1 to 10<-5>Torr order, and then, an inert gas is introduced to regulate the above pressure to 10<-3>Torr order. A voltage is impressed on the auxiliary cathode 7 to allow the auxiliary target 6 to discharge, and the degree of vacuum inside the chamber 1 is regulated to a degree of vacuum as high as 10<-7>Torr. A voltage is impressed on the main cathode 3 to allow the main target 2 of rare earth metal to discharge, by which a thin film of rare earth metal of alloy thereof can be formed on the surface of the substrate 5. By this method, the inside of the chamber 1 can be formed into a state of high degree of vacuum in a short time, and thin film formation can be carried out without causing deterioration in purity and magnetism.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for forming a rare earth metal thin film. More specifically, the present invention relates to a method and apparatus for forming a rare earth metal thin film using a sputtering method.

[Conventional technology]

Conventionally, a sputter link method has been used as one of the methods for forming metal thin films. In this sputtering method, the degree of vacuum in the vacuum chamber of the sputter link apparatus is set to 10-'' Tor before starting the formation of the metal thin film.
It is necessary to evacuate to a high degree of vacuum on the order of r, preferably on the order of 1.0-7 Torr.

For such evacuation, oil diffusion pumps, cryopumps, molecular turbo pumps, etc. are generally used.
Evacuation to the order of -7 Torr generally requires about 2 hours, although it depends on the volume of the vacuum chamber and the capacity of the pump.

Therefore, 10
When film formation is performed by sputtering on a -5 Torr table, active rare earth metals, such as Gd (gadolinium),
Tb (terbium), Dy (dysprosium), etc.
It combines with the small amount of residual oxygen that remains there, making it impossible to obtain a pure rare earth metal thin film.

[Invention or problem to be solved]

The present invention makes it possible to form a high degree of vacuum in the order of 1.0-7 Torr, which is necessary to form a pure rare earth metal thin film, in a relatively short time when forming a rare earth metal thin film using a sputtering method. The purpose of the present invention is to provide a method and apparatus for the same.

[Means to solve the problem]

The object of the present invention is to arrange a rare earth metal main target and a substrate facing each other in a vacuum chamber of a magnetron type sputtering apparatus, and an active metal auxiliary target not facing the substrate, respectively, and to After evacuation to the order of 10-5 Torr, inert gas was added to 1. (Up to the order of Y3 Torr, a voltage is applied to the auxiliary cathode to which the auxiliary targeter 1- is attached to discharge the active metal, thereby 10-7
After obtaining a high vacuum of Torr, voltage is applied to the main cathode on which the main target is mounted, thereby forming a thin film of rare earth metal or its alloy on the substrate surface.

FIG. 1 of the drawings is a schematic diagram of one embodiment of a film forming apparatus used to carry out the method of the present invention, in which a main can carrying a rare earth metal main target 2 is installed in the vacuum chamber of the magnetron type sputtering apparatus. 1-3 is on the lower side, a substrate 5 held by a substrate holder 4 is on the second side of the opposite position, and an active metal auxiliary targeter 1-6 is placed on the side of the substrate facing the inner wall of the chamber. Auxiliary cathodes 7 with attached cathodes are respectively installed. A main target cooling water pipe 8 and an auxiliary target cooling water pipe 9 are attached to the main cathode 3 side and the auxiliary cup 1 to 7 side, respectively, and the substrate holder 4 is rotated by a motor 0. ing.

As the rare earth metal serving as the main cathode 1, at least one of the above-described rare earth metals such as Gd, Tb, and Dy is mounted on the main cathode 2 in the form of a plate-shaped metal alone or in the form of an alloy. In addition, as the active metal that becomes the auxiliary targetera 1-,
For example, titanium, chromium, niobium, tantalum, zirconium, etc. are attached to the auxiliary cathode in the form of a single metal plate. The auxiliary cathode can be oriented in any direction as long as it is not facing the substrate, even if it is not facing the inner wall of the chamber, and its installation position is not limited to the side position of the substrate holder.

A rare earth metal thin film is formed using such a film forming apparatus as follows.

First, the inside of the vacuum chamber is evacuated (roughly evacuated) from the exhaust port 11 for about 10 minutes using a rotary pump.

After achieving a vacuum degree on the order of Torr, exhaustion (main evacuation) was performed for about 5 minutes using a combination of an oil diffusion pump and a rotary pump to obtain a degree of vacuum on the order of 10 −5 Torr. In addition, molecular turbo pumps and cryopumps are also used for exhaust.

Next, at a vacuum level on the order of 10-'Torr, an inert gas such as argon gas is introduced from the inert gas introduction pipe 12 until the vacuum level is on the order of 10-3 Torr, and the auxiliary cathode is supplied from the auxiliary target power source 13. A voltage is applied to 7 to discharge the active metal auxiliary target 6. As for the discharge conditions, in the case of DC, the applied voltage is about 200 to 300
V, a discharge current of about 0.5 to 2 people, and a discharge time of about 3 to 10 minutes are generally used. Note that when the discharge power supply is turned off under these discharge conditions, the inert gas introduction valve 12' is closed, and the degree of vacuum inside the vacuum chamber is measured, a high degree of vacuum on the order of 10'' Torr is obtained. was confirmed.

Once a high degree of vacuum on the order of 1.0-7 Torr has been achieved in this way, following the usual method,
Sputtering of rare earth metals onto a substrate surface such as a glass plate is performed. At this time, the discharge of the active metal auxiliary targeters 1~ is also continued at the same time.

That is, a voltage is applied from the main target power supply 14 to the main can 1-3, and the rare earth metal main target 2 is discharged.

At this time, pre-sputtering is performed with the shutter 15 closed. Thereafter, the shutter is opened and sputtering is performed to form a thin film of the rare earth metal or its alloy on the substrate surface. The discharge conditions are: in the case of DC, the applied voltage is approximately 200 to 6
00V, discharge current approximately 1-4A, discharge time approximately 1-5 minutes (
(shutter closed) and approximately 1 to 30 minutes (shutter open)
A rare earth metal thin film is formed on the substrate surface with a thickness depending on the discharge conditions.

[Operation] and [Effects of the Invention] A cathode equipped with an active metal targeter 1- is installed in a vacuum chamber of a magnetron type sputtering device, and after exhausting the inside of the vacuum chamber to the order of 10-” Torr, inert gas is evacuated to 10-” Torr. -Introduced up to the order of 3 Torr,
In this state, by applying a voltage to the cathode and discharging the active metal, the degree of vacuum in the vacuum chamber is reduced to 1.0-7.
It is possible to create a high vacuum in a relatively short time, up to the order of Torr. As shown in the example below and the graph in Figure 2, the time required for this process is 120 minutes when an oil diffusion pump and a rotary pump are used in combination, but with the present invention, the same degree of vacuum is only a short time. Achieved in 15 minutes.

The reason why high vacuum is achieved in a relatively short period of time is thought to be because the active metals scattered in the vacuum chamber space act as getters to capture residual oxygen, nitrogen, etc. in that space. Furthermore, although discharge of active metals occurs at the same time as discharge of rare earth metals, no active metals are detected in the thin film formed on the substrate surface by EPMA or mass spectrometry, which may impair the purity and magnetism of rare earth metals. Instead, thin film formation is performed.

〔Example〕

Next, the present invention will be explained with reference to examples.

EXAMPLE According to the embodiment shown in FIG. 1, titanium was used as the active metal, and Gd, which is a rare earth metal, was sputtered onto the surface of a glass plate.

First, inside the vacuum chamber, use a rotary pump to
After evacuation (rough evacuation) for 10 minutes until the pressure reaches 1.0-3 Torr, use a rotary pump and an oil diffusion pump to
The vacuum was evacuated to 5 x 10-'' Torr over a period of minutes.

If you continue the main draw in this state, 8. OX 10-7To
It took 120 minutes to reach a vacuum degree of rr. This situation is illustrated in the graph of FIG.

A: Rough pulling for 10 minutes B: Main pulling for 5 minutes C: Main pulling for 120 minutes After main pulling to 5 x 10-5 Torr, argon gas was introduced to 3,000 x 10-3 Torr, and in that state, the auxiliary power sword was Apply a voltage of 500v from a DC power supply,
A titanium auxiliary target was discharged. The discharge current at this time was 3A, and after 10 minutes of discharge, I turned off the power, stopped introducing argon gas, and measured the degree of vacuum.8.
It showed a value of OX 10-7 Torr. That is, although it took 120 minutes just by the main pump using the combined pump, the same degree of vacuum can be reached in just 15 minutes by discharging the titanium metal. This situation is also shown in the graph of FIG.

D: Argon gas introduced E: Titanium discharge for 10 minutes F: Titanium discharge stopped G: Titanium discharge resumed After 10 minutes of titanium discharge, the main cathode was also connected to the DC power supply at
A voltage of 0 V was applied and the gadolinium main target was discharged with a discharge current of 4 A. First, pre-sputtering was performed with the shutter closed for 3 minutes, then sputtering was performed with the shutter open for 10 minutes, and sputtering was performed on the surface of the glass plate attached to the substrate holder. A Gd thin film with a thickness of 3 μm was formed.

During this time, titanium was also discharged at the same time, but the formed G
d No titanium was detected in the thin film by EPMA or mass spectrometry.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of one embodiment of a film forming apparatus used to implement the method of the present invention. Moreover, FIG. 2 is a graph showing the time required to achieve a high degree of vacuum according to the method of the present invention. (Explanation of symbols) 1...Vacuum chamber 2...Rare earth metal main target 3...Main cathode 4...Substrate holder 5...Substrate 6... ... Active metal auxiliary target 7 ... Auxiliary cathode 11 ... Exhaust port 12 ... Inert gas introduction management agent Patent attorney Yoshi 1) Toshio

Claims (1)

[Claims] 1. In a vacuum chamber of a magnetron type sputtering apparatus, a rare earth metal main target and a substrate are placed in a positional relationship that opposes each other, and an active metal auxiliary target that is not in a positional relationship that faces the substrate, respectively, and the vacuum chamber is inside 10
After evacuation to the order of 5 Torr, inert gas was introduced to the order of 10^-^3 Torr, and a voltage was applied to the auxiliary cathode to which the auxiliary target was attached to discharge the active metal, thereby 10^- After obtaining a high degree of vacuum of ^7 Torr, a voltage is applied to the main cathode carrying the main target to form a thin film of the rare earth metal or its alloy on the substrate surface. Method. 2. A main cathode equipped with a rare earth metal main target in the vacuum chamber of the magnetron sputtering device;
A substrate held by a substrate holder at a position opposite to the main target, and an auxiliary cathode with an active metal auxiliary target attached facing the chamber inner wall at a position beside the substrate holder are installed, and an inert gas is applied to the vacuum chamber wall. Rare earth metal thin film forming equipment equipped with an inlet pipe. 3. Install a cathode with an active metal target in the vacuum chamber of a magnetron sputtering device,
The method is characterized in that after the inside of the vacuum chamber is evacuated to the order of 10^-^5 Torr, an inert gas is introduced to the order of 10^-^3 Torr, and in this state, a voltage is applied to the cathode to discharge the active metal. A high vacuum method that reduces the degree of vacuum in a vacuum chamber to the order of 10-7 Torr.