JPS5952955B2 - Method for manufacturing ultrafine particle material film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to materials for semiconductor sensors, more specifically, ultraviolet sensors that interact with external agents such as gases and water vapors and can detect the concentrations of gases and water vapors with high sensitivity. The present invention relates to a method for producing a particulate material film.

The present inventors previously proposed a sensor using ultrafine tin oxide particles.

Next, a method for manufacturing a tin oxide ultrafine particle material film as a semiconductor sensor material will be explained based on FIGS. 1 to 3.
A sample holder 2 in an ordinary vacuum evaporation apparatus 1 is made to hold a substrate (for example, a glass substrate) 3 to which an ultrafine particle material is to be attached.

Sn, SnO, or Sn is in the vapor deposition boat 4.
O. After setting the evaporation material 5, 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 approximately 5×10 −° To. then 0
The cock of the 0 gas inlet 7 is opened and 00 gas is introduced into the apparatus 1, and its pressure is maintained at about 0,1To or 10To. 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 a 00 gas atmosphere. For example, 00 gas pressure is O, 5To
Select Sn as the evaporation material 5, 70-80A, 4V
When power was applied to the boat 4 for 1 minute, an ultrafine particle material film of Sn oxide with a thickness of about 1 μm was deposited on the surface of the substrate 3. FIG. 2 shows an example of a sensor made as described above, in which a pair of electrodes 9 are placed on the substrate 3 in advance.
, 10 are provided by a method such as vacuum deposition,
Furthermore, an ultrafine particle material film 11 is formed thereon. When the sensor is placed in an atmosphere to be detected, the electrodes 9 and 10 will change depending on the concentration of gas and water vapor.
The resistance value between the two changes. Sn produced as described above
The characteristics of a sensor using an oxide ultrafine particle material film as a sensitive material vary considerably depending on its manufacturing method. As is clear from FIG. 1, in the method described above, the substrate is placed so that the ultrafine particle material is deposited almost perpendicularly to the flow of the ultrafine particle material. That is, as shown in FIG. 3, the substrate 3 has an angle of 900 with respect to the flow 12 of the ultrafine particle material. The present invention is for forming a metal or metal compound ultrafine particle material film on a substrate such as glass, ceramics, or SiO2 film by the above-mentioned evaporation method in a gas atmosphere. By making the angle between the flow of ultrafine particle material floating inside and the surface of the substrate with electrodes approximately parallel, an ultrafine particle film can be formed on the substrate, and the sensitivity and responsiveness of the sensor can be significantly improved. This was based on a new fact.

The present invention will be explained in detail below with reference to FIGS. 4 to 9.

The first manufacturing method according to the present invention is the one described in FIG. 1, in which the substrates on which the ultrafine particle material is formed are placed at approximately parallel angles. FIG. 4 is an enlarged view of a main part of an embodiment of the present invention, in which the substrate 3 is placed parallel to the flow 12 of ultrafine particle material, that is, at an angle of substantially 0°. FIG. 5 compares the responsiveness of a sensor manufactured in this manner and a sensor manufactured by a conventional method. In the figure, the dotted line a indicates the conventional example, and the solid line b indicates the sensor according to the present invention.

In either case, the element was left in the air until time 8, and its temperature was equal to room temperature, and at time 8, the heater for heating the element was turned on and the temperature of the element was raised to 350 °C.
After the resistance value of the element at 350°C stabilized, 8
At the time point, 20 cc of isobutane gas was introduced into the air atmosphere of about 51 °C, and the resistance of the element became stable in this atmosphere. and others? The change in soil type ￥ medium resistance is the case of conventional example pigeon ω) is the case of kelp of the present invention ・(b) is the response of 2~
It is 3 times better, and the sensitivity to gas is also about 2 times better.

Figure 6 shows the relationship between the angle between the substrate and the flow of ultrafine particle material and the element sensitivity, and it is clearly seen that the element sensitivity improves as the angle approaches 0°.

One of the reasons why the sensor characteristics vary greatly depending on the angle between the substrate and the flow of the ultrafine particle material when forming the ultrafine particle material film is thought to be the difference in the arrangement of the formed ultrafine particle material film. It will be done. FIG. 7 is a photograph of a cross-sectional structure of an ultrafine particle film sensor according to a conventional example, and FIG. 8 is a photograph of a cross-sectional structure of an ultrafine particle film sensor according to the present invention, observed with a scanning electron microscope.

As is clear from FIGS. 7 and 8, in the case of the present invention in which the angle between the substrate and the flow of the ultrafine particle material is approximately parallel, the ultrafine particle material film exhibits weak columnar properties in the direction perpendicular to the substrate;
Moreover, the surface of the ultrafine particle material film has conspicuous cauliflower-like unevenness. It is believed that the appropriate porosity and surface irregularities of such an ultrafine particle material film facilitate adsorption and desorption of gas, and provide excellent responsiveness and sensitivity of the device. FIG. 9 shows another embodiment for implementing the method of the present invention more reliably. In the above-mentioned FIG. 4, the angle between the substrate 3 and the flow 12 of ultrafine particle material is
In order to ensure that the angle is substantially parallel to 0°, a hollow cylindrical guide 13 is provided that surrounds at least a portion of the substrate 3 in the longitudinal direction, and the ultrafine particle material around the substrate 3 is It regulates the flow. As described above, according to the manufacturing method of the present invention, when forming an ultrafine particle material film, the substrate and the flow of the ultrafine particle material are simply placed approximately parallel to each other, and the ultrafine particle material film has excellent properties in both response and sensitivity. This method allows easy production of a particulate material membrane sensor, and is a very useful method industrially.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional view of an apparatus for manufacturing an ultrafine particle film sensor using a conventional method, Fig. 2 is a plan view showing an example of the structure of an ultrafine particle film sensor, and Fig. 3 is a conventional manufacturing method. FIG. 4 is an enlarged view of the main part showing the relationship between the substrate and the flow of ultrafine particle material according to the method of the present invention, and FIG. 5 is an enlarged view of the main part showing the relationship between the substrate and the flow of ultrafine particle material according to the method of the present invention. A characteristic diagram comparing the responsiveness and sensitivity of each ultrafine particle material film sensor produced by the manufacturing method and the manufacturing method of the present invention. FIG. 6 is a characteristic diagram showing the relationship between the angle between the substrate and the flow of the ultrafine particle material and the element sensitivity. , FIG. 7 is an electron microscope photograph of the cross-sectional structure of an ultrafine particle film produced by the conventional manufacturing method, FIG. 8 is an electron microscope photograph of the cross-sectional structure of an ultrafine particle film produced by the production method of the present invention, and FIG. FIG. 7 is an enlarged schematic diagram of a main part showing another manufacturing method of the invention. 3... Substrate on which an ultrafine particle material film is formed, 12.
...Flow of ultrafine particle material in a gas atmosphere, 13
...A hollow cylindrical guide that surrounds the board.

Claims (1)

[Claims] 1. A method for producing an ultrafine particle material film, which comprises: placing a substrate approximately parallel to the flow of ultrafine particle material in a gas atmosphere, and forming an ultrafine particle material film on the surface of the substrate. . 2. A substrate is installed approximately parallel to the flow of ultrafine particle material in a gas atmosphere, a hollow cylindrical guide that surrounds at least a portion of the longitudinal direction of the substrate is installed approximately parallel to the substrate, and the substrate is A method for producing an ultrafine particle material film, the method comprising forming an ultrafine particle material film on a surface.