JPH0788271B2 - Method of manufacturing oxide thin film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing an oxide thin film used as a substrate when producing an oriented thin film or an epitaxial thin film.

2. Description of the Related Art In order to produce an oriented thin film or an epitaxial thin film, it is required that the thin film and the substrate material have similarities in crystal structure, symmetry, interatomic distance and the like. In particular,
Conventional dielectric epitaxial films and alignment films are sapphire and
It is often manufactured using an oxide single crystal such as MgO as a substrate.

For example, a thin-film element that uses pyroelectric current generated in the orientation axis direction by providing an electrode on a surface perpendicular to the orientation axis of a lead titanate thin film oriented in the <001> direction has a larger pyroelectric coefficient than the non-oriented one. It was reported at the 30th Japan Society of Applied Physics (Proceedings 7p-Z-2) that the dielectric constant becomes low and the figure of merit (pyroelectric coefficient / dielectric constant) of the pyroelectric material becomes large.
The <001> oriented lead titanate thin film cleaved at (100)
It grows on MgO single crystal substrate.

The characteristics of a thin film device formed on a substrate are greatly affected by the characteristics of the substrate itself and the interaction between the thin film and the substrate. Therefore, the pyroelectric infrared sensor and the piezoelectric vibrator have been proposed to have a structure in which the main part of the substrate is removed. Also, an integrated device in which an epitaxial thin film is formed after growing an intermediate layer on a semiconductor substrate has been proposed.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The oxide single crystal substrate is used as a substrate for various devices by cutting a single crystal block into thin pieces and polishing the surface. In general, a thin substrate is preferable in many cases, but there is a limit to reducing the thickness of the substrate. Furthermore, it is difficult to produce (110) and (111) plane field substrates by cleavage for other crystal planes such as MgO single crystal.

Further, when manufacturing an integrated device using a semiconductor substrate, it is difficult to selectively epitaxially grow a minute portion on the semiconductor substrate by using an oxide single crystal substrate.

Means for Solving the Problems When a magnesium oxide is produced by a sputtering method on a semiconductor substrate or a glass substrate, a mixed gas of an inert gas and oxygen is used as a sputtering gas, and the mixed gas contains 50% or more of oxygen. Film formation is performed in an atmosphere to produce magnesium oxide oriented in the <111> direction or the <100> direction.

Action Magnesium oxide (11
1) and (100) can be selectively produced with good reproducibility. Further, since it can be easily manufactured on a semiconductor substrate or a glass substrate, an integrated device can be realized.

Example Magnesium oxide was produced on a Si (100) substrate by a high frequency magnetron sputtering method. Substrate temperature 40
It changed from 0 to 700 ℃. As the atmosphere gas, argon gas mixed with oxygen was used, and the total pressure was 4 Pa.
The RF input power 1.5 ^- was 6.5 W / cm @ 2. A thin film of magnesium oxide having a desired film thickness was obtained. The crystal orientation of the obtained thin film was determined by X-ray diffraction.

FIG. 1 shows the relationship between the X-ray diffraction intensity and the argon / oxygen gas mixture ratio. When the oxygen gas exceeds 50%, (20
The (0) and (111) intensities increased, and the (220) peak was almost undetectable. Here, since magnesium oxide is a face-centered cubic lattice, (100) and (110) reflections are not detected, but since (200) and (220) reflections are detected, the thin film is oriented in the direction perpendicular to the substrate surface. At (100) and (1
It can be seen that it is oriented in 10). However, the substrate temperature is
It is at 600 ° C.

FIG. 2 shows an X-ray diffraction pattern when the substrate temperature is changed. It is when oxygen gas is 50%. The relationship between the X-ray diffraction intensity and the substrate temperature is shown in FIG. Only the reflection intensity of (200) increases at 500 ° C, and only (111) increases at 700 ° C. In other words, at a low temperature of 600 ℃ (100)
Becomes dominant and becomes (100) orientation at 500 ° C. At the high temperature side, (111) becomes predominant, and at 700 ° C, it becomes (111) orientation.

FIG. 4 shows the relationship between the (200) reflection intensity and the film formation rate. The (200) reflection intensity increases with the film formation rate.

Effects of the Invention According to the production method of the present invention, magnesium oxide (111)
It is possible to selectively produce the (100) and (100) with good reproducibility, and it is possible to easily produce the (111) plane, which has been difficult to produce conventionally, without using expensive magnesium oxide. Further, since it can be easily manufactured on a semiconductor substrate or a glass substrate, an integrated device can be realized.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing the relationship between the X-ray diffraction intensity and the argon / oxygen gas mixture ratio, and FIG. 2 is a diagram showing the X-ray diffraction pattern when the substrate temperature is changed based on the manufacturing method of the present invention. FIG. 3 is a characteristic diagram showing the relationship between the X-ray diffraction intensity and the substrate temperature, and FIG. 4 is a characteristic diagram showing the relationship between the (200) reflection intensity and the film formation rate.

Claims (3)

[Claims] 1. In a step of producing magnesium oxide on a substrate by a sputtering method, a mixed gas of an inert gas and oxygen is used as a sputtering gas, and the film is formed in an atmosphere containing 50% or more of oxygen. <111
A method for producing an oxide thin film, which comprises producing magnesium oxide oriented in the> direction or the <100> direction. 2. A step of producing magnesium oxide by a sputtering method, the substrate temperature is set to 700 ° C. or higher, and <111
The method for producing an oxide thin film according to claim 1, wherein magnesium oxide oriented in the> direction is produced. 3. A step of producing magnesium oxide by a sputtering method at a substrate temperature of 500 ° C. or lower at <100.
The method for producing an oxide thin film according to claim 1, wherein magnesium oxide oriented in the> direction is produced.