JPS62222616A - Heat-resistant electrode thin film - 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] [Industrial Application Field] The present invention provides heat-resistant 1! The present invention relates to ultra-thin films, especially heat-resistant electrode thin films that are durable even under severe conditions such as high temperatures, oxidizing atmospheres, or reduced pressure.

[Conventional technology]

When electrical and electronic parts and devices are used at high temperatures, or when the manufacturing process includes heat treatment with electrodes attached, it is necessary to use heat-resistant materials for such electrodes. . For example, the process of manufacturing a capacitor using ferroelectric ceramics includes a step of attaching electrodes and then firing at a high temperature. In this case, since inexpensive base metals do not have heat resistance, noble metals are usually used as the electrode material. The electrode is formed as a thick film typically by a printing method. However, since a large amount of expensive precious gold is used, this is one of the causes of increasing costs. As a measure to overcome such economical disadvantages, it has been proposed to reduce the amount of electrodes used by making them thinner. However, the thinned IE electrode has many problems in terms of heat resistance.

Due to the difference in thermal expansion coefficient between the electrode thin film and the substrate/base material on which it is attached, phenomena such as cracking and peeling occur during the process of raising the temperature to a high temperature or during the process of cooling after raising the temperature. Second, when an electrode thin film is subjected to high temperature treatment, some metals may evaporate due to their vapor pressure, making the thin film even thinner and increasing its resistance, making it useless as an electrode. Third
This means that the metal material that forms the electrode thin film may diffuse heat into other materials that are in surface contact with it. This is because the particles in a thick film are relatively large, whereas in a thin film, the particles are formed in an almost atomic state.

The above-mentioned problems with the heat resistance of Dentaku'4 films are not only seen in bulk ceramic electrical and electronic parts and devices, but also when thin film electrical and electronic parts and devices are used at high temperatures or subjected to high-temperature heat treatment. This can also be seen when creating.

Specific examples are shown below.

When forming an oxide thin film such as a ferroelectric material after forming an electrode thin film on a heat-resistant insulating substrate, the sputtering method involves heating the substrate at a temperature of 10-3 to 10-2 Torr at a high temperature of 500°C or higher.
It is necessary to keep it under reduced pressure of about r. In that case, TI, A
In the case of a thin electrode film such as T, a problem arises in that it volatilizes or thermally diffuses, impairing the conductivity of the electrode. As another example, when a StO□ layer is formed on a Si substrate by steam oxidation with an electrode thin film attached on an 81 substrate, approximately 1
Heat to 0000.

Under these two harsher conditions, electrode thin films such as Au will volatilize. Furthermore, many base metals are oxidized and lose their conductivity.

[The problem that the invention is trying to solve]

In the present invention, the temperature is about 500°C or higher, preferably 550 to 160°C.
The object of the present invention is to provide a heat-resistant electrode thin film that has durability at a high temperature of 0° C. and under severe conditions such as an oxidizing atmosphere or reduced pressure, and does not impair electrical conductivity.

[Means for solving problems]

According to the present invention, there is provided an electrode thin film formed by forming a thin film of iridium, platinum, flat radium, ruthenium, rhodium, or two or more of these on a substrate by a 4@ formation method such as sputtering, vapor deposition, or CVD. be done.

In the present invention, the thickness of the thin film is determined based on electrical conductivity, vorticity, positioning of electrodes in the device, etc., but is generally 0.
, 01 to 5 μm, preferably 0.05 to 1 μm. If the blade is too thick, the conductivity will be poor and the resistance will be high; if the blade is too thick, it will be uneconomical.

Examples of the substrate on which the electrode thin film of the present invention is provided include commonly used ceramics, glass, single crystal thin films, and the like.

The electrode r4 film can be made into an amorphous state depending on the production conditions or the relationship with the substrate, and it can also be made into a <111> oriented crystal film or a (100) oriented crystal film, so it is especially suitable for creating oriented thin films. Become useful.

Methods for producing the ultra-thin heat-resistant 'tel film disclosed in the present invention include a DC sputtering method, a high-frequency sputtering method, a high-frequency magnetron sputtering method, and a vacuum evaporation method.

There are thin film forming methods such as electron beam evaporation and CVD.

In the case of the sputtering method, each metal is used as the target material which is the evaporation source. Any sputtering gas may be used as long as it can generate a discharge. Argon (Ar) is usually used, but there is no problem even if it contains an oxidizing gas such as oxygen. Furthermore, the electrode thin film of the present invention can be created under normal conditions using a thin film forming method such as a vapor deposition method or a CVD method.

The electrode thin film of the present invention is useful as an electrode for electrical or electronic parts or devices that are used at high temperatures or are created through a process that involves high-temperature heat treatment. Furthermore, the ML Tsuru thin film of the present invention is economically advantageous because the amount used is considerably less than the thick metal film produced by the printing method. If the substrate on which the ultra-thin film is applied is made smooth, it will have good smoothness, making it suitable for use as electrodes for thin-film electric and electronic parts and devices.

[? Thin film materials include iridium, platinum,
), radium, ruthenium, rhodium, etc., preferably iridium, palladium, ruthenium, rhodium, etc. may be used alone or in combination of 21 or more. Examples of the combination of two or more types include platinum-iridium, platinum-parazoum, iridium-ruthenium, platinum-iridium-rhodium, and the like.

Example 1 An iridium thin film was formed on a mirror-finished 7937100-sided substrate by high-frequency magnetron sputtering. The board temperature for the spanter is 300℃.

The sputtering gas was set to 2xlOTorr of aluminum + sputtering power of 1 to 5W/α2. Iridium film thickness 0
．． A thickness of 25 μm was prepared. The X-ray diffraction diagram is shown in the attached drawing, and it is a (111) oriented crystal film.

The conductivity of this iridium thin film is good, with a resistivity of 10-50.
・It was less than α.

The sample with this iridium thin film was heated to 600°C under a reduced pressure of 10-2 Torr and held for 3 hours, then cooled to room temperature and taken out into the atmosphere, but the thickness and resistivity of the iridium thin film did not change at all. There wasn't.

Example 2 A sample with an iridium thin film prepared in the same manner as in Example 1 was held at 70°C in air for 3 hours. Although it was cooled to room temperature, the film thickness and crystal structure of the iridium thin film did not change at all, and the resistivity was 1o-50.1 or less.

Example 3 An iridium thin film was formed on a silicon 100 substrate in the same manner as in Example 1. Next, a titanium v lead lanthanum zirconate (PLZT) thin film was formed thereon.

The PLZT thin film was formed by a sputtering method using PLZT as a target, a substrate temperature of 300° C., and a mixed gas of argon and oxygen as a sputtering gas to deposit it to a thickness of about 2 μm. Thereafter, it was held at 700° C. for 3 hours in air to form a PLZT thin model of Velopsky 11. Even though PLZT sputtering and heat treatment were performed on the iridium thin film in this way, the film thickness and resistivity of iridium 4jl were the same as in the original state, and the function as an electrode thin film was maintained.

Example 4 A thin platinum film was formed on a sapphire substrate by sputtering. The following conditions were that the substrate temperature was 500° C., the temperature was platinum, and a mixed gas of argon and oxygen was used as the sputtering gas to form a platinum thin film with a thickness of about 0.4 μm by high-frequency magnetron sputtering.

The platinum thin film at room temperature after sputtering was a (111> oriented crystal film, and the resistivity was 10-50·α or less.

This sample was held at 700°C for 3 hours under a reduced pressure of 10-2 Torr. When the film was cooled to room temperature and discharged into the atmosphere, the film thickness was approximately 0.05 μm. Further, the resistivity was about 10-40·cm.

Example 5 Except for changing the iridium in Example 1 to 79 radium,
A flat radium thin film was formed on a 100-sided mirror silicon substrate by the same method as in Example 1.

The thickness of the palladium thin film is 0.1 μm, and the resistivity is 10-
It was 50.α. The formed palladium thin film sample was heated to 600°C under a reduced pressure of 10 Torr for 3
After holding for a certain period of time, the palladium thin film was cooled to room temperature under reduced pressure and discharged into the atmosphere, but there was almost no change in the thickness of the palladium thin film and no change in resistivity.

Example 6 A ruthenium thin film was formed on a 100-sided mirror silicon substrate by the same method as in Example 1, except that iridium in Example 1 was replaced with ruthenium.

The thickness of the ruthenium thin film is 0.5 μm, and the resistivity is 10-
It was less than 5Ω·1. The formed ruthenium thin film sample was heated to 600°C under a reduced pressure of 10 Torr and held for 3 hours, then cooled to room temperature under reduced pressure and taken out into the atmosphere, but there was almost no change in the film thickness. No change was observed in the resistivity of the ruthenium thin film.

Example 7 A rhodium thin film was formed on a 100-sided silicon substrate by the same method as in Example 1, except that iridium in Example 1 was replaced with rhodium (film thickness 0.2 μm, resistivity 10).
Ω・1 or less). Next, zircon titanate modified lanthanum lead "4@" was formed thereon in the same manner as in Example 3, but the composition changed due to the chemical reaction with the rhodium thin film and the properties as a ferroelectric material deteriorated. was not observed, indicating that it retained sufficient functionality as an electrode.

Comparative Example 1 A gold (Au) layer with a thickness of about 0.5 μm was formed on a mirror-finished 100-sided silicon substrate by vacuum evaporation. The conductivity of the gold thin film in this state is good, with a resistivity of 10 Ω.
・It was less than α. However, while heating the sample with the gold thin film to 600°C under a reduced pressure of 10 Torr,
After being held for a period of time, it was cooled to room temperature and taken out into the atmosphere, and the thickness of the gold thin film was 0.01 μm or less. The resistivity was 10Ω·α or more, and it was no longer usable as an electrode thin film.

Comparative Example 2 A thin Ti film was deposited on a sapphire substrate using an electron beam evaporation method.
．． A thickness of 2 μm was deposited. Resistivity is approximately 10-5Ωφ
It was 1 or less. This sample was held at 600° C. for 3 hours under a reduced pressure of 10 −2 Torr. After cooling to room temperature, it was taken out to atmospheric pressure, and the resistivity was found to be 10Ω·α or more.

[Brief explanation of drawings]

The drawing is an X-ray diffraction diagram of the iridium thin film of Example 1 of the present invention.

Claims (3)

[Claims] (1) An electrode thin film formed by forming a thin film of iridium, platinum, palladium, ruthenium, rhodium, or two or more of these on a substrate by a thin film forming method such as sputtering, vapor deposition, or CVD. (2) The electrode thin film according to claim 1, wherein the thin film has a thickness in the range of 0.01 to 5 μm. (3) The electrode thin film according to claim 1, wherein the thin film has a thickness in the range of 0.05 to 1 μm.