JPH03193865A - Formation of pbo2 thin film - Google Patents

Abstract

PURPOSE:To control the quality of a film and to efficiently form the film at a high vapor deposition rate by cluster ion beam vapor deposition by using a gaseous oxygen introducing device to excite, dissociate and ionize gaseous oxygen in the vicinity of a substrate. CONSTITUTION:The gaseous oxygen introducing device consisting of a reactive gas introducing device 4, a gas ion generator 9 and a power unit 10 for the gas ion generator is used. A region, in which the gaseous oxygen is excited, dissociated and ionized (activated state), is formed in the vicinity of the substrate 7, especially of its vapor deposition surface. The vapor-deposition material injector consisting of the vapor source 1, ionizer 2, accelerating electrode 3 and power unit is then used to inject the vapor of Pb as the vapor-deposition material by cluster ion beam deposition, and the vapor is allowed to chemically react with the activated gaseous oxygen.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for forming a PbO2 thin film. More specifically, the present invention relates to a method of depositing a PbO2 thin film on a substrate by cluster ion beam deposition.

[Prior Art] Conventionally, oxide thin films such as TlO2, 8102, PbO2, etc. have been formed on substrate surfaces by methods such as sputtering and CVD. However, the oxide thin film formed on the substrate surface by this method has drawbacks such as insufficient hardness and weak adhesion to the substrate.

Therefore, as a method to obtain a thin film without such defects,
A reactive cluster ion beam (R-ICB) method is used in which a thin compound film is formed by ejecting the vapor of a deposition material into a reactive gas atmosphere using a cluster ion beam method.

This R-ICB method will be explained below using FIG. 2.

Figure 2 is from the Journal of Applied Physics (J
, Appl, Phys, ), 58(11), 1985
, p. 4146-4149.
FIG. 2 is an explanatory diagram of the device. In the figure, (1) is a closed crucible 02) with a nozzle (l+), crucible 0
2) A steam generation source consisting of a crucible heating filament and a heat shield plate 04). The above-mentioned Ruppo 0 is for filling the vapor deposition material sphere and ejecting the vapor on the vapor deposition material surface from the nozzle (II) on the crucible side to form a cluster (massive atomic group) Oe. (2 is an ionization device for ionizing cluster OG,
It consists of an electron beam emitting filament (21), an electron beam extraction electrode for extracting and accelerating electrons from the filament C21+, and a heat shield plate. (3) is an acceleration electrode for accelerating ionized clusters with an electric field and imparting kinetic energy to the clusters; (4) is a gas cylinder filled with oxygen gas (41); and a vacuum chamber (6) for storing oxygen gas. A reactive gas introduction device (5) is composed of a flow ffi adjustment valve (42) for introducing oxygen gas into the air and a gas introduction pipe (43) for introducing oxygen gas into the vacuum chamber (6). (7) is a substrate on which a thin film is formed. (8) houses first, second, and third bias DC power supplies (81), (82), and (83) and first and second filament heating power supplies (84) and (85). This is a power supply device.

First, the functions of each bias power supply of the power supply device (8) will be explained. The first bias DC power supply (8■) is a crucible heating power supply so that thermionic electrons emitted from the crucible heating filament n heated by the first filament heating power supply (84) collide with the crucible Oz. Bias the potential of Ruppo 02) positively with respect to the filament ■. The second bias DC power supply (82) biases the electron beam emitting filament (21+) heated by the second filament heating power supply (85) to a negative potential with respect to the electron beam extraction electrode n. Filament for electron beam emission (211
Thermionic electrons emitted from the electron beam are extracted into the electron beam extraction electrode■. In addition, a third bias DC power supply (83)
biases the electron beam extraction electrode n and the crucible 02) to a positive potential with respect to the accelerating electrode (3), which is at ground potential, and controls the acceleration of positively charged cluster ions by the electric field lens formed between them.

Next, a method for forming a PbO2 thin film using the above-mentioned apparatus will be explained.

First, the inside of the vacuum chamber (6) is 1×
After evacuation to a degree of vacuum of approximately 10' Torr, the flow ffi adjustment valve (42) is opened while evacuation is being performed, and oxygen gas is introduced into the vacuum chamber (6) through the gas introduction pipe (43).

Next, under this condition, the crucible heating filament 0 is heated to a temperature where the vapor pressure inside the crucible (12) becomes several Torr.
When the electrons emitted by the electric field applied by the first bias DC power source (81) collide with Ruppo 021 and heat it, Pb6, which is the evaporation material, evaporates and the nozzle 0
1) is injected into the vacuum. When the injected Pb vapor passes through the nozzle 01), it becomes supercooled due to adiabatic expansion) and forms a lumpy atomic group called a cluster aQ. Then some cluster Oe
are ionized by electrons emitted from the electron beam emitting filament to become cluster ions, which are further accelerated toward the substrate by the electric field formed by the accelerating electrode (3) and form the substrate ( 7) Collisions. On the other hand, since oxygen, which is a reactive gas, exists near the substrate (7),
The reaction between Pb vapor and reactive gas (Pb + 0
2'' Pb02) is then deposited onto the substrate, forming a PbO2 thin film.

[Problems to be Solved by the Invention] In the conventional Pb0 thin film forming method as described above, an apparatus configured such that the ejected reactive gas and Pb vapor are ionized by the same ionization apparatus (2) is used. Therefore, the reactive gas cannot be sufficiently excited, dissociated, and ionized, and the reactive gas in the vacuum chamber (6) remains in a molecular state with low activity, and some of the reactive gas remains in the ionization device (2). ) Even if the excited, dissociated and activated elements formed near the substrate (7) have short lifetimes, they return to a less active state near the substrate (7), and most of the reactive gas is exhausted. Therefore, there is a problem that very little reactive gas participates in thin film formation, resulting in poor vapor deposition efficiency.

In addition, as mentioned above, since the same ionization device (2) is used, the amount and kinetic energy of ionized Pb accelerated toward the substrate and the amount of ionized reactive gas are controlled. It is difficult to control the film quality because the kinetic energy cannot be changed independently.

The present invention has been made to solve these problems, and it is possible to efficiently and stably coat high-quality Pb on the surface of the substrate.
It is an object of the present invention to provide a method for forming an O2 thin film by vapor deposition.

[Means for Solving the Problems] The present invention is a method for forming a PbO2 thin film on a substrate, and includes an oxygen gas introduction device comprising a reactive gas introduction device, a gas ion generation device, and a power supply device for the gas ion generation device. A device is used to form a region in which oxygen gas exists in an excited, dissociated, and ionized state near the substrate, and a vapor deposition material ejection device consisting of a vapor generation source, an ionization device, an accelerating electrode, and a power supply device is used to form a cluster. Pb vapor, which is a vapor deposition material, is ejected into the region using an ion beam method and chemically reacts with the oxygen gas in the above state, thereby forming PbO.
2 thin film is formed on the substrate.
The present invention relates to a method for forming an o2 thin film.

[Example] Hereinafter, the method of the present invention will be explained based on FIG.

FIG. 1 is an explanatory diagram of an apparatus used when forming a Pbo2 thin film by the method of the present invention, and parts similar to those of the apparatus shown in FIG. 2 are given the same reference numerals.

In FIG. 1, (1) is a steam generation source consisting of a closed crucible side having a nozzle (01), a crucible heating filament (2) for heating the crucible (+2), and a heat shield plate (04). The crucible 0'2J contains Pb (
Pb vapor is ejected from the nozzle 01) of the crucible to form clusters.

(2) is an ionization device for ionizing clusters, and is composed of an electron beam emitting filament (2D1), an electron extraction electrode for extracting and accelerating electrons from around this filament, and a heat shield plate. (3) ) accelerates the ionized cluster with an electric field,
(4) is an accelerating electrode for imparting kinetic energy to the cluster; (4) is a gas cylinder (41) filled with oxygen gas;
), a flow rate adjustment valve (42) for introducing oxygen gas into the vacuum chamber (6), and a gas introduction pipe for introducing oxygen gas (
43) and a reactive gas introduction device consisting of a gas injection nozzle (44), (5) a vacuum exhaust system for maintaining the vacuum chamber (6) at a predetermined degree of vacuum, and (7 a thin film on its surface). (8) is the substrate on which the first, second, and third bias DC power supplies (81), (82), and (83) can be formed.
and first and second filament heating power supplies (84), (8
5) is the power supply device that is housed. The first bias DC power source (81) supplies the crucible heating filament n heated by the first filament heating power source (84).
The crucible (12) is connected to the crucible heating filament n so that the thermoelectrons emitted from the crucible (12) collide with the crucible (02).
This is to bias the potential of . The second bias DC power source (82) biases the electron beam emitting filament heated by the second filament heating power source (85) to a negative potential with respect to the electron extraction electrode, thereby emitting the electron beam. This is for extracting the thermoelectrons emitted from the filament (211) into the electron extraction electrode n.In addition, the third bias DC power supply (83
) biases the electron extraction electrode and the crucible (12) to a positive potential with respect to the accelerating electrode (3), which is at ground potential, and forms an electric field lens between them to control the acceleration of positively charged cluster ions. belongs to. (9) is a second electron beam emitting filament (92) provided in a portion corresponding to the reactive gas passage, a second electron beam extraction electrode (91) for extracting the electron beam, and reactive gas ions. A second accelerating electrode (93
), a gas ion generator consisting of an electric field shield plate (95) and an internal tank (94) that shields the entirety of these, (
) is a third filament heating power source (101) for heating the second electron beam emitting filament (92).
), the electron beam extraction electrode (91) is connected to the electron beam emission filament (92) and the electric field shield plate (9
5) and a fourth biasing DC power supply (102) for biasing to a positive potential with respect to the second accelerating electrode (9).
3) is a power supply device for a gas ion generator, which is comprised of a fifth bias DC power supply (103) for applying a voltage.

In the method of the present invention, an oxygen gas introduction device consisting of a reactive gas introduction device (4), a gas ion generator (9), and a power supply device for the gas ion generator (to) is used to Oxygen gas is excited near the surface of the evaporation surface,
A region is formed that exists in a dissociated and ionized state (hereinafter also referred to as an active state).

The oxygen gas introducing device is a device for partially exciting, dissociating, and ionizing oxygen gas, and ejecting the oxygen gas toward the substrate.

In order to form the region near the surface of the substrate vapor deposition surface using the introduction device, the following operation may be performed.

That is, first, the vacuum chamber (6) is opened by the vacuum evacuation system (5).
) is made into a high vacuum of about 10-8 Torr, and while continuing to exhaust, the oxygen gas whose flow rate is adjusted by the flow rate adjustment valve (42) is injected into the gas injection nozzle (44).
gas pressure in the vacuum chamber (6) is 10' to 1O.
Adjust the flow rate to about -3 Torr.

Next, in this state, the second electron beam emitting filament (92) provided in the electric field shield plate (95)
2 by the third filament heating power source (101)
The second electron beam extraction electrode (91
), a bias voltage is applied by a fourth bias DC power supply (102) so that an electron beam is emitted,
2~ from the second electron beam emitting filament (92)
Emit an electron beam of about 5A.

By emitting an electron beam to the ejected oxygen gas, a part of the oxygen gas is excited, dissociated, and brought into an ionized state (active state). At this time, a fifth bias DC power supply ( 103) to apply an accelerating voltage to the second accelerating electrode (93) to accelerate the ionized oxygen gas and electron beam toward the substrate (sword).
The vicinity of the surface of the substrate evaporation surface is activated.

The acceleration voltage is preferably about 0.5 to 2 kV.

In this way, by using the oxygen gas introduction device, the amount and kinetic energy of oxygen ions accelerated toward the substrate can be controlled by changing the acceleration voltage.

Next, the vapor of Pb, which is the vapor deposition material, is vaporized by the cluster ion beam method using a vapor deposition material ejecting device consisting of a vapor generation source (1), an ionization device (2), an accelerating electrode (3), and a power supply device (8). Squirt into the area.

The vapor deposition material ejecting device is a device for partially ionizing vapor and clusters of the vapor deposition material, and ejecting and accelerating the vapor toward the substrate.

In order to eject Pb vapor into the region using the cluster ion beam method using the ejecting device, the following operation may be performed.

That is, the crucible heating filament heats the crucible 02) to a temperature at which the vapor pressure of Pb becomes approximately several Torr, evaporates the Pb, and injects it from the nozzle (II). When the Pb vapor passes through the nozzle 01), it becomes supercooled due to adiabatic expansion and forms clusters.

This injected Pb vapor and clusters are partially ionized by the electron beam emitted from the electron beam emitting filament (2tl), and are accelerated by the electric field formed by the accelerating electrode (3), so that they are not ionized. It collides with the substrate (7) together with vapor and clusters.

The electron beam emission amount is usually about 0.1 to 0.5A.

The acceleration voltage is preferably about several kV.

In this way, when the vapor deposition material ejecting device is used, the kinetic energy of ions such as clusters can be controlled by changing the accelerating voltage.

Oxygen gas is excited near the substrate (7) as described above,
In a state where a region exists in a dissociated and ionized state, Pb vapor or clusters are ejected toward the substrate, colliding with the activated oxygen gas and causing a chemical reaction (Pb+O2- Pb02),
A PbO2 thin film can be efficiently formed on the substrate (7'): Next, the method of the present invention will be explained with reference to an example using the apparatus shown in FIG.

Example 1 First, the inside of the vacuum chamber (6) was
After evacuation to 10'Torr, oxygen gas was injected from the gas injection nozzle (44) while continuing evacuation.

At this time, the gas pressure in the vacuum chamber (6) is controlled by the flow rate adjustment valve (
42) to adjust the pressure to about 10' to 10-3 Torr.

Next, in this state, the second electron beam emitting filament (92) is heated to about 2000° C., and a bias voltage is applied. The OA electron beam was emitted.

At the same time, an accelerating voltage (1 kV) was applied to the second accelerating electrode (93) by the fifth bias DC power source (103).

Then the crucible 02 is heated by the crucible heating filament n.
) is heated until the Pb vapor pressure in
Steam was injected from nozzle (II). At this time, the electron beam (0
, 2 A), and an accelerating voltage (3 kV) was applied by the third bias DC power supply (83).

By the method of the present invention, a dense Pb0z thin film with excellent adhesion and flatness can be obtained.

As described above, in the method of the present invention in which the oxygen gas introduction device and the vapor deposition material ejection device are provided separately,
In particular, since oxygen gas is excited and dissociated and exists in an extremely highly active state near the surface of the substrate vapor deposition surface, the chemical reaction between the vapor deposition substance and the oxygen gas is promoted, and a PbO2 thin film can be efficiently formed.

In addition, by independently changing the acceleration voltages of the oxygen gas introduction device and the deposition material jetting device, it is possible to independently control the reactive gas ions incident on the substrate and the kinetic energy of the deposition material vapor and clusters. This makes it possible to control the film quality, such as crystallinity and adhesion, of the PbO2 thin film formed on the substrate (7), making it possible to form a high quality thin film.

[Effects of the Invention] According to the present invention, a region in which oxygen gas exists in an excited, dissociated, and ionized state is formed near the substrate using an oxygen gas introduction device, and a region where oxygen gas exists in an excited, dissociated, and ionized state is formed using an oxygen gas introduction device, and a region where oxygen gas exists in an excited, dissociated, and ionized state is formed using an oxygen gas introduction device. Since the Pbo2 thin film is formed by injecting Pb vapor using the cluster ion beam method, the film quality can be controlled at a high deposition rate, and a high quality thin film with strong adhesion can be efficiently formed. I can do it.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an apparatus used for forming a Pbo2 thin film according to the method of the present invention, and FIG. 2 is an explanatory diagram of a conventional oxide thin film forming apparatus. (Main symbols in the drawing) (1): Steam generation source (2): Ionization device (3): Accelerating electrode (4): Reactive gas introduction device (7), Substrate (8): Power supply device (9): Gas ion generator M: Power supply type for gas ion generator Yu Iwamasu, Faculty of Science and Humanities University

Claims (1)

[Claims] (1) A method for forming a PbO_2 thin film on a substrate, in which oxygen gas is introduced near the substrate using an oxygen gas introduction device consisting of a reactive gas introduction device, a gas ion generator, and a power supply for the gas ion generator. forming a region in which the vapor exists in an excited, dissociated and ionized state
By using a vapor deposition material ejecting device consisting of an ionization device, an accelerating electrode, and a power supply device, the vapor of Pb, which is the vapor deposition material, is ejected into the region using the cluster ion beam method and chemically reacts with the oxygen gas in the above state.
2 thin film is formed on the substrate.
Method for forming O_2 thin film.