JPS6015123B2 - temperature sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature sensor that utilizes the change in electrical resistance of a semiconductor due to temperature, that is, a so-called thermistor. The purpose of the present invention is to provide a temperature sensor with sufficient durability.

Conventionally used thermistors are made by forming and condensing a heat-sensitive material such as a metal oxide semiconductor into a bead shape or disc shape, which is then coated with resin or the like, or housed in a glass or metal container. there were.

These thermistors have the drawback of slow response speed due to the large volume of the heat sensitive body itself, that is, the large heat capacity, and the poor thermal conductivity and large heat capacity of the coating and container. The temperature sensor of the present invention is characterized in that both the heat sensitive body and the coating have a film-like structure, thereby reducing the heat capacity without impairing durability. A temperature sensor according to an embodiment of the present invention will be described below.

FIG. 1 is a cross-sectional view showing an embodiment of a temperature sensor according to the present invention. On the surface of a substrate 1 made of an insulator, a heat-sensitive film 2 made of a metal oxide semiconductor, an electrode 3, a corrosion-resistant and abrasion-resistant Coating films 4 made of films are sequentially laminated and lead wires 5 are attached. Although the substrate 1 is used to hold the film, it can be omitted as shown in FIG. 2 if a particularly long response speed of 0.1 seconds or less is required. In this case, the device can be easily fabricated by constructing the entire device on the surface of a suitable substrate, such as resin, and then peeling off the substrate or removing it with a solvent. As a material for the heat-sensitive film 2, a metal oxide semiconductor is excellent in resistance-temperature characteristics and heat resistance. Various specific compositions have been developed so far, all of which can be put to practical use, but in particular, mixtures of Mn, Co and Ni oxides, or mixtures of two of these components are preferred. The ones that do so show superior properties. Since the resistance-temperature characteristics and specific resistance of these materials change depending on the composition ratio, it is sufficient to select a composition ratio that matches the desired characteristics. Note that methods for forming these materials into a film include a printing method and various other vapor deposition methods, such as a vacuum vapor deposition method, a sputter vapor deposition method, an ion plating method, and the like. The appropriate thickness of this heat-sensitive film is, for example, several loAm in the case of a printing method, and several tenm in the case of a vapor deposition method. However, these films lack corrosion resistance and have the disadvantage that their characteristics change significantly depending on humidity. The present inventors have discovered that it is effective to coat this heat-sensitive film with a certain type of film in order to eliminate this drawback. As this coating film,
Materials with higher electrical resistance than thermosensitive films and excellent corrosion and abrasion resistance, such as various glasses, oxides such as alumina, carbides such as silicon carbide and shelving carbide, nitrides such as aluminum nitride, etc. was found to be appropriate. Among these, silicon carbide coatings are particularly thermally and chemically stable, and have excellent corrosion resistance against various atmospheres such as strong acids and strong alkaline gases, such as oxidizing gas atmospheres, and are resistant to the effects of humidity. It has been found to be suitable as a material for coatings because it has many characteristics, such as being resistant to damage, has excellent abrasion resistance, and has good thermal conductivity, so response speed is not impaired. The methods for forming these films are as follows:
The various vapor deposition methods, vapor phase growth methods, etc. mentioned above are used.
In the case of silicon carbide, a good film can be easily obtained by using a sputter deposition method, an ion plating method, or a vapor phase growth method. The thickness of the corrosion-resistant and wear-resistant coating is, for example, several meters to several meters.
Approximately 0 French m is appropriate. In this case, as the thickness of the silicon carbide film increases, the strain generated within the silicon carbide film causes
The silicon carbide film is finally peeled off from the heat-sensitive film.

In order to reduce this peeling, it is recommended to insert an adhesive layer between the heat-sensitive film and the silicon carbide film, and it has been discovered that a composite film of silicon carbide and silicon oxide is particularly effective as the adhesive layer. This composite coating can be made by combining, for example, a silicon carbide coating with SIC.
It has been found that when forming by high frequency sputtering deposition using a target, it can be easily obtained by performing sputtering deposition in an oxidizing atmosphere immediately after the start of deposition. In order for this adhesive layer to work effectively, the thickness of the adhesive layer must be at least a certain value, and the thickness needs to be increased when the silicon carbide coating is thick. Upon closer examination, the present inventors discovered that it is approximately 10% of the silicon carbide coating.As described above, the temperature sensor according to the present invention has a fast response speed, and has excellent corrosion and wear resistance. It has an unprecedented feature of being excellent in terms of temperature, and can be widely used for temperature detection under various usage conditions.

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing an embodiment of a temperature sensor according to the present invention. 1...Substrate, 2...Thermosensitive film, 3...Electrode, 4...
・Abrasion resistance, 5...Lead wire. Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1. A temperature sensor characterized in that the surface of a heat-sensitive film made of a metal oxide semiconductor is coated with a silicon carbide film. 2 In claim 1, the metal oxide semiconductor is Mn-Ni, Mn-Co, Co-Ni, Mn-Co.
- A temperature sensor comprising at least one selected from oxides of Ni. 3. A temperature sensor according to claim 1 or 2, characterized in that an adhesive layer made of a composite of silicon carbide and silicon oxide is inserted between the silicon carbide film and the thermosensitive film.