JPS5814503B2 - Nisanca vanadium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for manufacturing vanadium dioxide (V02) thin films.

■ A single crystal with a temperature of 0 is semiconducting electrical resistance (R8 (Ω)
1cm)) to metallic electrical resistance (Rm (Ω1Cm))
It shows changes such as having .

Generally, the change ratio (Rs/Rm) is 10-3 to 10-4?
It has been reported that this phenomenon can be used to reduce the heat capacity of
0 thin film switches and the like have been proposed.

This manufacturing method involves heating the substrate to about 100°C in a vacuum of about IXIO-5 Torr, directly depositing vanadium M, and then heating and oxidizing it in an oxygen atmosphere at 500°C for 2 hours.
A common method is to obtain a VO2 thin film.

However, this force method can only obtain a change in sheet resistance from about 104Ωcm to about 2×102Ω1cm, and in order to obtain a large change factor, it is necessary to carefully repeat the method described above. A change ratio of 103 to 104 cannot be obtained unless sufficient care is taken in setting the oxygen pressure and heat treatment temperature.

Even with this method, the value that can be practically obtained is at most 103, and the smaller this change magnification is, the more conspicuous a hysterinism phenomenon occurs in the resistance change magnification.

The present invention aims to provide a method for producing a vO2 thin film that can stably obtain a change factor of 104 without heat oxidation treatment,
Specifically, oxygen plasma is formed in a vacuum, and an oxide such as ■ or v205 is heated and evaporated into this plasma.
The present invention relates to a method of exposing this vapor to oxygen plasma to obtain a desired VO2 thin film on a substrate.

A typical manufacturing apparatus will be explained with reference to FIG.

A substrate 2 and a vapor deposition substance 3 are placed facing each other in a vacuum container 1.

For thermal evaporation, a method of resistively heating the tungsten board 4 using a power source 5 is shown, but electron beam heating or other methods may also be used.

The vapor deposition material 3 may be either a V metal or an oxide of V, but (2) the force using the metal as a starting material is easy to control.

Oxygen plasma is formed between the substrate 2 and the deposition material 3.

This example shows an example in which plasma is generated by high-frequency glow discharge.

In order to create a thin film with a large resistance change factor, it is best to create a state in which high-brightness white light emission can be observed, that is, a line spectrum due to the energy transition of oxygen atoms can be observed.

By supplying high frequency power of, for example, 13.56 MHz to the high frequency electrode 6 from the high frequency power supply 7, a high frequency glow discharge is generated.

The inside of the vacuum container 1 is 1×10-5 in advance by the pump 8.
After exhausting to about Torr ~ 1 x 10-6 Torr,
A reaction gas 10 is introduced under the control of a control valve 9, and a high-frequency glow discharge is generated at a predetermined pressure.

The reaction gas 10 may be 100% oxygen or a mixture of oxygen and an inert gas such as Ar, but good results can be obtained with 100% oxygen.

A positive or negative DC voltage can be applied to the substrate 2 by the power supply 11 depending on the situation, but this setting value does not have a large influence on the performance of VO2, but it does affect the adhesion between the substrate and the thin film. plays an important role.

12 is an insulation introduction terminal.

Figure 2 shows the relationship between the input high-frequency power and the resistance change magnification. When the oxygen pressure PO2 reaches IXIO-2 Torr, the film formation rate becomes extremely slow due to the mean free path relationship, and when the oxygen pressure PO2 reaches IXIO-2 Torr, the film formation rate becomes extremely slow. When it becomes a vacuum, it becomes technically difficult to generate and maintain plasma, and the practical range of the degree of vacuum is 8 x 10-3 Torr to 5 x 10-5 Torr. Resistance change magnification increases.

This shows that there are differences in the power contained in the various phases of (1)203 to V205, and that they become closer to VO2.

From the figure, it can be seen that the input high frequency power should be 400W or more.

In addition, in Figure 2, the vacuum vessel 1 is prepared in advance using the apparatus shown in Figure 1.
After exhausting the inside to 10-6 Torr, oxygen (100%
) and set the respective pressure to 1 x 10-2 Torrt.
This is data when three points of 8X10-3 Torr and 8X10-4 Torr were selected, and the high frequency power was adjusted respectively to form an oxide film starting from V metal using an electron beam heating evaporation source.

Furthermore, FIG. 3 shows the relationship between the 02.Ar partial pressure ratio and the resistance change magnification when metal is used as the starting material and the input high frequency power is 500 W.

It can be seen that the resistance change factor increases as the oxygen concentration increases.

Further, FIG. 4 shows the relationship between input high frequency power and resistance change magnification using v205 as a starting material.

From the data in FIGS. 3 and 4, it can be seen that the same resistance change ratio can be obtained even if the starting material is a V metal or a V oxide.

Although the substrate may be heated, it is not necessarily a necessary condition for producing a VO2 film, and according to the present invention, room temperature is sufficient.

By the manufacturing power method of the present invention as described above, an average of 104 to 5
A VO2 thin film having a resistance change magnification of X10' can be obtained, and the thin film exhibits almost no hysteresis phenomenon and is of high utility value.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional front view of a device used to produce a flame using the manufacturing force method according to the present invention, including an electric circuit. FIG. 3 is a resistance change magnification characteristic diagram for the same oxygen concentration rate, and FIG. 4 is a resistance change magnification characteristic diagram for input high frequency power under other conditions. 1... Vacuum container, 2... Substrate, 3... Vapor deposition substance, 6...
High frequency electrode, 7... High frequency power source.

Claims (1)

[Claims] 1 A substrate and an evaporation source made of vanadium or vanadium oxide are placed facing each other in a vacuum container, and oxygen plasma is applied to the space between them at a pressure range of 8X10-3 Torr to 5X10-5 Torr and a high frequency power of 400 W or more. A method for producing a vanadium dioxide thin film, comprising: generating a vanadium dioxide thin film, and exposing material vapor from the evaporation source to the oxygen plasma to obtain a vanadium dioxide thin film on the substrate.