JPS6030893B2 - How to manufacture the sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a sensor, and more specifically, a sensor that interacts with external agents such as gas and water vapor, and is capable of detecting the concentration of gas and water vapor with high sensitivity. The present invention relates to a method of manufacturing a sensor using an ultrafine particle film of tin oxide as a sensitive material.

An object of the present invention is to provide a sensor that can detect the concentrations of gas and water vapor with high sensitivity by using the same material and simply changing the measurement temperature.

That is, the tin oxide ultrafine particle sensor produced by the manufacturing method of the present invention is sensitive to water vapor at room temperature and gas at high temperature, and can selectively detect the concentrations of each of them. It is. Hereinafter, one embodiment of a method for manufacturing an ultrafine tin oxide particle material as a semiconductor sensor material will be described in detail with reference to FIG.

A substrate (for example, a glass substrate) 3 to which ultrafine particle material is to be attached is held in a sample holder 2 in an ordinary vacuum evaporation layer.

Sn, Sn0, or Sn in the vapor deposition boat 4
After setting the evaporation material 5 such as 02, a vacuum pump (not shown) connected to the exhaust port 6 is operated to bring the inside of the apparatus 1 to a degree of vacuum of 5×10-ord star degrees. after that,
The cock of the 02 gas inlet 7 is opened to introduce the 02 gas into the apparatus 1, and its pressure is maintained at about 0.1 Torr to lmon. Next, the boat 4 is energized by the evaporation power source 8 to generate heat, and the evaporation material 5 is evaporated for a few seconds to several minutes in an 02 gas atmosphere. For example, 02 gas pressure is 0.9
0n and select Sn as the evaporation material 5, 70-80A, 4
When a power of V was applied to the boat 4 for 1 minute, ultrafine particles of Sn oxide with a thickness of about 1 m were deposited on the surface of the substrate 3.

Here, we have given an example of a method using resistance heating to evaporate the evaporation material, but other methods such as induction heating,
Alternatively, it goes without saying that a method using infrared heating may be used. FIG. 2 shows an example of a sensor made as described above.

In this case, a pair of electrodes 9 and 10 are previously provided on a substrate 3 by a well-known method such as vacuum deposition, and an ultrafine particle film 11 is further formed thereon. When placed in an atmosphere to be detected, the resistance value between the electrodes 9 and 10 changes depending on the concentration of gas and water vapor.
The characteristics of a sensor using the Sn oxide ultrafine particle material produced as described above as a sensitive material vary considerably depending on its production conditions. Among the various manufacturing parameters that affect the properties, the properties are particularly strongly dependent on the atmosphere in which the ultrafine particle material is formed, that is, the pressure of the 02 gas. Taking the average particle diameter of the ultrafine particle material as an example, as shown by the solid line in FIG. 3, it is over 100 A when the 02 gas pressure is lmom, and several tens of A when the 02 gas pressure is ITorr. Generally, the proportion of the surface in the particle and the proportion of surface energy in the total energy of the particle vary greatly depending on the particle size of the ultrafine particle material. As shown by the broken line in Figure 3, the ratio of the number of surface atoms to the total number of atoms in the ultrafine particle material produced at the 02 gas pressure lmom is approximately 10%, and that of the ultrafine particle material produced at the 02 gas pressure ITon is approximately 45%. %. As described above, the surface energy of the ultrafine particle material, that is, the surface activity that causes interaction with gas and water vapor, differs depending on the Q gas pressure during production. Furthermore, the state of film formation when the ultrafine particle material adheres to the substrate also differs depending on the 02 gas pressure. That is, when the Q gas pressure is 0.1 Ton,
As shown in FIG. 4A, the ultrafine particle layer is arranged in a columnar manner in the C-axis direction, and its surface is relatively flat, with cracks occurring here and there. This suggests that the ultrafine particle film is quite hard and brittle (closely packed with small particles). When the 02 gas pressure reaches 0.5 Tom, as shown in FIG. 4B, although the columnar nature still remains, disturbances begin to be seen in the arrangement direction of the ultrafine particle layer.

This indicates that the size of the ultrafine particles is considerably large (approximately 30 A as shown in FIG. 3), and the bonding force between the ultrafine particles is also weaker than in the case of 0.1 Ton. When the 02 gas pressure reaches 10 rorr, as shown in FIG. 4C, there is no directionality in the growth of the ultrafine particle layer, and of course the columnar character also improves, and the cross-sectional structure becomes spongy.

The surface structure, like the cross-sectional structure, is spongy. Figure 5 shows
This figure shows the dependence of the sensitivity of the Sn oxide ultrafine particle material to imptan gas and water vapor on the 02 gas pressure during the production of the ultrafine particle material.

As mentioned above, the growth and arrangement of the ultrafine particle material itself and the ultrafine particle material film differ depending on the 02 gas pressure, so naturally the interaction with the atmosphere, such as isoptane gas and water vapor, will also differ depending on the S-core oxide ultrafine particle material. It varies depending on the 02 gas pressure during manufacturing.

In the figure, curve a shows the sensitivity of the Sn oxide ultrafine particle material to isobutane gas measured in a temperature atmosphere of 200 qo. As is clear from this, 0
2 Sn oxide ultrafine particle material produced at a gas pressure of 0.1 ton to lmon has sensitivity to isobutane. Curve b shows the sensitivity of the S-hard oxide ultrafine particle material to sobutane gas measured in a temperature atmosphere of room temperature (25°C), and shows no sensitivity regardless of the Q gas pressure during production.Curve c is 20 pi 0
This shows the sensitivity of Sn oxide ultrafine particle material to water vapor measured in a temperature atmosphere of . Curve d shows the sensitivity of the Sn oxide ultrafine particle material to water vapor measured in a room temperature atmosphere. have. As is clear from this, 0.
The Sn oxide ultrafine particle material produced in a Q atmosphere at a pressure of 1 ton to ITon can selectively detect isobutane gas when measured at 200 qo and water vapor when measured at room temperature.

As described above, the Sn oxide ultrafine particle material produced by the manufacturing method of the present invention can selectively measure, for example, isoptan gas and water vapor existing in the same atmosphere with one sensor by simply changing the measurement temperature. , is very useful.

As is clear from the above, it is economical because one sensor can measure one event.
Another advantage is that the peripheral circuit configuration is much easier than using two sensors. Sensors made using this method can be used, for example, to detect or control combustion conditions, and to detect fires.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a manufacturing apparatus for implementing the sensor manufacturing method according to the present invention, FIG. 2 is a plan view showing an example of the structure of a sensor obtained by the method of the present invention, and FIG.
The figure shows the relationship between the Q gas pressure, the average particle diameter of the ultrafine particle material, and the number of surface atoms during the production of the sensitive material.
C is a scanning electron micrograph showing the state of adhesion of the Sn oxide ultrafine particle material to the substrate, and FIG. 5 is a diagram showing the relationship between 02 gas pressure, measurement temperature, and sensitivity during the production of the sensitive body. 1... Board, 4... Boat, 5...
...Evaporation material, 9,10...Electrode, 11...
...Ultrafine particle film. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1 Evaporate Sn or its oxide on an electrically insulating support substrate in an atmosphere of O_2 gas pressure of 0.1 to 1 Torr and adhere to the support substrate to form an ultrafine particle film of Sn oxide. A method for producing a sensor characterized by using the sensor as a humidity sensitive body.