JPS5840694B2 - Manufacturing method of gas/humidity sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a gas/humidity sensor, which is composed of an aggregate of ultrafine metal oxide particles with an average particle size in the range of 10 to over 100 amps, and is resistant to gases, water vapor, etc. The object is to provide a method by which highly sensitive sensors can be manufactured very easily.

It has been found that when a sensitive film is composed of ultrafine metal oxide particles with an average particle diameter of 10 A to over 100 A, the resistance changes sensitively to gas and water vapor.

The present invention can further improve the sensitivity of such a receptor.

Hereinafter, the details will be explained by giving examples.

As shown in FIG. 1, a pair of electrodes 2 and 3 are formed on an insulating substrate 1 made of glass or ceramics, and then a metal oxide such as tin, titanium, zinc or nickel is further applied thereon. A metal oxide ultrafine particle film 4 is formed.

The production of an ultrafine particle film of tin oxide will be explained using FIG. 2 as an example.

A substrate 1 having electrodes 2 and 3 as shown in FIG.
is attached so that the surfaces on the electrodes 2 and 3 side face downward in the drawing.

Further, an evaporation material 14 such as Sn, 5nO1, or Sn02 is set on the evaporation board 13.

Then, a vacuum pump (not shown) connected to the exhaust port 15 is activated to reduce the inside of the device 11 to 10' Torr.
After the degree of vacuum is on the order of , the oxygen gas inlet 16
The cock is opened, 02 gas is introduced into the device 11, and its pressure is maintained at, for example, about 0.5 Torr.

Next, the board 13 is energized by the evaporation power source 17 to generate heat, and the evaporation material 14 is evaporated for a few seconds to several minutes in an 02 gas atmosphere.

For example, if Sn is selected as the evaporation material 14, 70 to 8
0A.

When a power of 4■ is applied to the board 13 for 1 minute, approximately 1μm
An ultrafine particle film 4 of Sn oxide was formed on the substrate 1 as shown in FIG.

Here, a method using resistance heating has been described as an example to evaporate the evaporation material, but it goes without saying that other methods such as induction heating or infrared heating may also be used.

The substrate 1 that has gone through the above steps is placed in a predetermined container, and
After the gas is allowed to flow at a flow rate of 1 t/min, oxygen gas plasma is generated in the container by applying high frequency power, and the substrate is left in the oxygen gas plasma atmosphere for about 30 minutes.

This process will be referred to as activation processing.

Ultrafine metal oxide particles are extremely sensitive to external agents such as gas and water vapor, but when they are subjected to the activation treatment described above, they become even more sensitive.

For example, as shown in Figure 3, the sensitivity of ultrafine Sn oxide particles to isobutane gas increases with the increase in high-frequency applied power for forming 02 gas plasma, and becomes almost saturated when it exceeds a certain value. .

At this time, the sensitivity to isobutane gas is approximately 1.8 times higher than that before the tin oxide ultrafine particles are activated by oxygen gas plasma.

Note that this measurement was performed by bringing air containing 0.2 volumes of isobutane gas into contact with a tin oxide ultrafine particle film maintained at a temperature of 300°C.

As described above, according to the manufacturing method of the present invention, by exposing a film made of ultrafine metal oxide particles to oxygen plasma, its sensitivity to external agents can be greatly improved, resulting in high sensitivity. gas/humidity sensors can be easily manufactured.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of a gas/humidity sensor manufactured by the gas/humidity sensor manufacturing method according to the present invention;
FIG. 2 is a diagram showing an example of an apparatus for manufacturing an ultrafine tin oxide particle film, and FIG. 3 is a diagram for explaining the effect of activation treatment of the ultrafine tin oxide particle film. 1... Substrate, 2, 3... Electrode, 4...
...Oxide ultrafine particle film.

Claims (1)

[Scope of Claims] 1. After forming an ultrafine particle resistance film composed of an aggregate of ultrafine metal oxide particles with an average particle size in the range of 10 to 100-odd A, on an electrically insulating support substrate, The resistive film is activated by contact with oxygen plasma, and gases and water vapor can be detected by utilizing the fact that the electrical resistance value of the resistive film changes depending on the type and concentration of the gas to be detected. A method for manufacturing a gas/humidity sensor. 2. The method of manufacturing a gas/humidity sensor according to claim 1, wherein the metal oxide ultrafine particle film is formed of tin oxide ultrafine particles.