JPS62272402A - Manufacture of 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 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to a method for producing a thin film of a substance having a perovskite structure, which is known to have excellent various electrical properties.

BACKGROUND OF THE INVENTION A perovskite structure is a crystal structure formed when the ionic radius of the B ion is considerably smaller than the radius of the A ion in a compound represented by the chemical formula ABo3.

In this structure, B ions and six oxygen ions are BO
Since this BO2 forms an octahedron of 2 and tends to have spontaneous polarization, it has various excellent electrical properties. Therefore, thin films of substances having this structure are expected to be applied to various devices.

Conventionally, high-frequency sputtering using an ABO3 compound target has been mainly used to fabricate thin films of this type of material. [For example, Shigeru Hayayo and Kiyotaka Wasa "Thin film technology" (1986)
．． December), Kyoritsu Shuppan.

P, 168:1 By performing sputtering at a substrate temperature of about 600° C. or higher, a crystalline thin film with a perovskite structure can be obtained. Although polycrystalline thin films are usually produced using the above method, single-crystalline thin films are desired when particularly good properties are required.

To produce a single-crystal thin film, a single-crystal material with a similar crystal structure is used as a substrate, and by setting appropriate growth conditions, it is possible to obtain a film with the same crystal orientation as the substrate. In order to fabricate a single crystal thin film with a perovskite structure, it is necessary to use MgO as a substrate, S r Tio3゜77 Ia C
ct-A/203), spinel (M g A l
204).

A single crystal material such as GaP or GaAs is used as the substrate.

Problems to be Solved by the Invention However, since the substrate is a single crystal, it is expensive, and therefore devices using a single crystal thin film are also inevitably expensive and have limited applications.

Furthermore, materials with a perovskite structure are composite oxides of two or more elements, and because each element has different vapor pressure, degree of oxidation, mutual affinity, etc., it is generally very difficult to produce a single crystal thin film. That is, there was a problem in that the reproducibility in producing a single crystal thin film having a perovskite structure was not very good.

Means for Solving the Problems The present invention solves the above problems by separating the evaporation sources containing the human material and the B material and attaching them alternately to the substrate when producing a thin film with a perovskite structure (ABO3). The film is formed using the following steps.

Operation The present invention has succeeded in producing a single crystal thin film having a perovskite structure or a similar crystalline thin film even on an amorphous substrate with good reproducibility using the above method.

As schematically shown in FIG. 2, the perovskite structure has 21 A atoms. B atoms 22 and oxygen atoms 23 are arranged.

Considering metal atoms other than oxygen atoms, for example, 1oO
> direction, layers of A atoms and B atoms alternate at intervals of 11,
In the 111> direction, layers are alternately arranged at intervals of 12. The present inventors made the following surprising experiment: By alternately depositing oxide layers of A and B atoms, a single crystal thin film with any orientation reflecting the above structure can be created even on an amorphous substrate. The present invention was carried out based on the results. Furthermore, when a single crystal substrate was used, reproducibility was significantly improved.

As a method for forming films by depositing them alternately, the evaporation sources containing A and B are separated and the amount of evaporation of each is controlled, or a shutter is provided between the substrate and the evaporation source to control the evaporation amount, or the substrate is controlled periodically. This can be easily done by moving the evaporation source and periodically changing the relative position with respect to each evaporation source. In addition, by alternately changing the composition of the atmospheric gas during thin film fabrication,
It is also possible to form a film of human material and B material.

EXAMPLES In order to better understand the content of the present invention, the present invention will be explained below using specific examples.

The quaternary composite oxide PLZTC (general formula (Pb, La) (Zr, Ti) 03) is a substance with a perovskite structure containing pb and La as A atoms and Zr and Ti as B atoms, and It is known that various properties can be exhibited by selecting the composition of the material. In particular, the composition PbO, 9LaO, I ZrO, 65T'
Those around 0.3503 have excellent electro-optic effects, so
This thin film is expected to have good applications in electro-optical devices. The properties required of the thin film in this case are high transparency and electro-optical properties, and single crystal thin films are optimal for these.

FIG. 1 shows an overview of the thin film produced by applying the manufacturing method according to the present invention to the thin film. Pb 11 as an individual evaporation source
, La 12 , Zr 13 , and Ti 14 sputtering targets are arranged so as to focus on one point. For the substrate 15, inexpensive quartz glass was used. The substrate holder 16 has a heating wire 17 of approximately 70 mm.
Heated to 0°C. Contact point 1 between holder 16 and rotating shaft 18
9 is rotatable, and the holder 16 is rotated by rotating the shaft 18.
The mechanism is such that the head swings. Due to such swinging motion, the heater wire 17 is not twisted. The substrate 16 is repeatedly opposed to each target in the order of Pb, La, Zr, and Ti, and only when the substrate 16 is opposed, the material of the target is deposited. To perform sputtering, first set the chamber containing the target and substrate at 1×10
Evacuate to a degree of vacuum of Pa, Aτ102 = 2/1
A negative voltage was applied to the target under a vacuum of 3 Pa.

Each target generates a discharge (1a, 1b, 1c, 1d), and the target material evaporates due to ion bombardment. The input power of each target is Pb: 20W,
La: 1ow, Zr: sow.

The Ti near power was set to 0W, and the swinging period of the substrate was set to 6 seconds. Under these conditions, the deposition rate is P b /L a =9/1, Z r /T i =
65/35, and the amount of film formation of PB and La oxides and the film formation amount of Zr and Ti oxides are both about 1.2 per cycle.

In other words, the oxide layers of material A and material B of the perovskite structure are stacked alternately by 1.2 layers, and this length almost matches the layer spacing between material A and material B in the 111> direction. . When sputter deposition was carried out for 1 hour under the above conditions, a thin film of about 150 OA was produced. When the crystallinity of the film was evaluated by X-ray diffraction, it was found that a (111)-plane PLZT single crystal film was obtained despite the glass substrate.

Next, other embodiments of the present invention will be described.

In the sputtering apparatus, only the swinging period of the substrate is set to 10
Sputter deposition was carried out on quartz glass and SUS 147C surface substrates instead of seconds. Under these conditions, the amount of Pb and :La oxides and the amount of Zr and Ti oxides formed per period are approximately two each. This is approximately the same as the layer spacing between the human material and the B material in the 100> direction. After all, a thin film of about 150 OA was formed by sputtering for 1 hour.

A single crystal thin film of (100) plane was obtained on the quartz glass substrate. Although the (111) plane of PLZT normally grows on a 147C plane substrate due to its crystal structure, the film produced was almost a (1oo) plane.

By changing the lamination period as described above, a single crystal thin film with any orientation could be produced on any substrate.

Effects of the Invention As described above, the thin film manufacturing method of the present invention provides a method for manufacturing a perovskite type single crystal thin film, which has conventionally been manufactured only on a single crystal substrate, on any substrate and with any orientation with good reproducibility. Therefore, the industrial value of the present invention is extremely large.

[Brief explanation of the drawing]

FIG. 1 is an overview diagram of thin film production in one embodiment of the present invention;
FIG. 2 is an atomic arrangement diagram of a perovskite structure. 11...pb met, 12...L
a target, 13...Zr target, 14
...Ti target, 15...quartz glass substrate, 16...substrate holder, 17...
... Heater wire, 18 ... Rotating shaft, 19 ...
... Rotatable contacts, 1a, 1b, 10, 1d...
...Target discharge, 21...A atom, 22
...B atom, 23... River oxygen atom. Name of agent: Patent attorney Toshio Nakao (1 person)
---pb target/2---L target/3--4r target/4--7; Target/S--One stone disaster power glass 4 prongs Fig. 1 Fig. 2

Claims (5)

[Claims] (1) In producing a thin film of a substance having a perovskite structure (ABO_3), the evaporation sources containing the A material and B material are separated, and the films are formed by alternately depositing the materials on the substrate. A method for manufacturing a thin film. (2) The thin film according to claim 1, characterized in that the film is formed by controlling the evaporation amount of the evaporation source containing the separated materials A and B, and depositing each material alternately on the substrate. manufacturing method. (3) The thin film according to claim 1, characterized in that the film is formed by controlling a shutter provided between the evaporation source and the substrate to alternately attach material A and material B to the substrate. manufacturing method. (4) A patent claim characterized in that film formation is performed by alternately depositing material A and material B on the substrate by periodically moving the substrate and changing the relative position between the substrate and each evaporation source. A method for producing a thin film according to scope 1. (5) Manufacture of the thin film according to claim 1, characterized in that the film is formed by changing the composition of the atmospheric gas during thin film formation and depositing material A and material B alternately on the substrate. Method.