JPH04151881A - Manufacture of thin film thermoelectric device - Google Patents

Abstract

PURPOSE:To obtain a high thermo-electric power and a thin film thermoelectric device capable of operating even in a high temperature region by laminating a thin film thermocouple pattern consisting of impurities arrayed alternately as a donor and an acceptor and a thin film thermocouple pattern made of an iron silicide film so that they may be formed on an insulation substrate respectively and carrying out their heat-treatment as well. CONSTITUTION:A substrate 1 is covered with a mask and Co, which serves as a donor, is sputtered so that a Co thin film 4 is laminated and clad on one side of each thermocouple of the thermocouple patterns of an iron silicide film 2. Then, Mn, which serves as an acceptor, is sputtered so that a thin Mn film 6 may be clad on the surface. After the cladding, the whole substrate is heat- treated in vacuum so that Co and Mn may be diffused on the thin iron silicide film 2 respectively, thereby producing an n type thin semiconductor film 7 and a p type thin semiconductor film 8 respectively and constituting a thermopile to which a plurality of thermocouples are connected in series. This construction makes it possible to provide a thin film thermoelectric device which is small in size, high in sensibility, and excellent in heat resistant properties.

Description

DETAILED DESCRIPTION OF THE INVENTION (Al Industrial Field of Application) This invention relates to a method of manufacturing a small and highly sensitive thermoelectric element used in infrared centers, temperature centers, heat sensors, etc.

(Bl. Prior Art) So-called mobile thermoelectric elements, in which a large number of thermocouples are connected in series, have been developed for use as infrared sensors, temperature sensors, heat centers, etc.

In general, a thermopile type thermoelectric element has a structure in which a large number of thermoelectric materials are connected in series and thermoelectromotive force generated from a temperature difference is added, and a large thermoelectromotive horn can be obtained. This allows it to be used as a highly efficient thermoelectric conversion element or as a highly sensitive infrared, temperature, or heat sensor that detects minute temperature differences. In particular, for sensor applications, miniaturization, increased sensitivity,
Thin film thermoelectric elements are mainly used to increase response speed.

In a conventional thin film thermoelectric element, a thin wire pattern made of an n-type thermoelectric material and a thin wire pattern made of a p-type thermoelectric +A material are formed on a substrate, and thermocouples are connected in series by further forming electrodes.

Thermoelectric materials for such conventional thin film thermoelectric elements include constantan-nichrome (Japanese Patent Publication No. 57-40154), As
-Te (JP 53-132282), Si, Ge (
Half-W body materials such as JP-A-57-7172) and B1-3b-Te (JP-A-61-22676) have been used.

(C) Problems to be Solved by the Invention These conventional thermoelectric materials have the advantage of low resistivity and high thermoelectric conversion efficiency, but they have the disadvantage that they cannot be used at high temperatures because they have a small Seebeck coefficient and are easily oxidized. have.

SUMMARY OF THE INVENTION An object of the present invention is to solve these conventional problems and provide a method for manufacturing a thin film thermoelectric element for a sensor, which is thin, has a high thermoelectromotive force, and can be used even in a temperature range.

Means for solving the fd1 problem In order to achieve the above object, a material that can be used at high temperatures and has a high Seebeck coefficient is required.A silicide semiconductor has a high Seebeck coefficient of 300 to 700 μV/, It has high heat resistance and is attracting attention as a thermoelectric power conversion element at high temperatures.

The inventors have discovered that by making an iron silicide semiconductor material into a thin film, a thermopile type thermoelectric element with high sensitivity and usable even at high temperatures can be obtained.

The method for manufacturing a thin film thermoelectric element of the present invention involves laminating a thin film thermocouple pattern formed by alternately arranging impurities as donors and acceptors and a thin film thermocouple pattern made of an iron silicide film on an insulating substrate, and then applying heat treatment to the thin film thermocouple pattern. The method is characterized in that the impurity is thermally diffused into the iron silicide film to form a thermocouple pattern of an iron silicide n-type semiconductor film and an iron silicide p-type semiconductor film.

(Q1 Effect) In the method for manufacturing a thin film thermoelectric element of the present invention, a thermocouple pattern of an iron silicide film and a thermocouple pattern of an impurity film are formed as thin films on the insulating substrate, respectively.

Then, by heat treatment, impurities are thermally diffused into the iron silicide film, and the region where the donor is diffused becomes an n-type semiconductor, and the region where the acceptor is diffused becomes a p-type semiconductor. As a result, a thermocouple pattern of the iron silicide n-type semiconductor film and the iron silicide p-type semiconductor film is formed on the insulating substrate. Since the iron silicide film, which is an intrinsic semiconductor, and the impurity as a donor or acceptor for it are formed into thin films in the shape of a thermocouple pattern, it is possible to precisely control the amount of each component. , a thin film thermoelectric element made of an iron silicide semiconductor film having a desired carrier concentration can be obtained.

(flEmbodiment) An embodiment of the present invention will be explained in the order of manufacturing steps based on FIGS. 1 to 8.

First, Fe and Si powders are mixed and melted in a high frequency melting furnace.
It is melted at 600°C, cast into a disk-shaped mold, and cooled. As a result, a disk-shaped iron silicide ingot is obtained. Then, the surface is polished to obtain an iron silicide target.

Next, as shown in FIG. 1, using a mask on the SiO□ substrate 1, the iron silicide target is subjected to RF sputtering in AI to form an iron silicide thin film 2 in the shape of a thermocouple pattern. The sputtering conditions at this time are as follows.

Substrate temperature = 300°C High frequency power: soow ~ 1.5 kW Rate: 1 ~ 10 μm/hr Next, as shown in Figure 2, the substrate is covered with a mask 3 with an opening in the portion where the donor is diffused, and CO as a donor is diffused. A
RF sputtering in r.

The sputtering conditions at this time are as follows.

Substrate temperature: 150 degrees Celsius Frequency output: 500 W to 1.5 kW Rate: 2 to 20 μrn/hr As shown in FIG. A Co thin film 4 is laminated and deposited on each.

Next, as shown in FIG. 4, using a mask 5 with openings formed in the portion where the acceptor is to be diffused, M.
RF sputtering of n in Ar. The sputtering conditions at this time are as follows.

Substrate temperature: 150"C High frequency output power 500W~1.5kW Rate power 1~15μm/hr As a result, the surface of the iron silicide thin film is
n! A membrane 6 is applied.

Thereafter, the entire substrate is heat-treated in a vacuum at 1200 to 1300°C. As a result, as shown in FIG. 6, Co and Mn are diffused into the iron silicide thin film (1), forming p-type semiconductor thin films 7 and 8, which have hot and cold junctions at the center and periphery of the substrate, respectively. Many thermocouples are connected in series.
Mobile is configured.

Finally, as shown in FIG. 7, an electrode material is deposited using a mask 9 with a notch formed in the terminal forming part.
As shown in FIG. 8, the lead attachment forms terminals 10.11.

In the embodiments shown above, the number of thermocouple pairs is small in order to make the drawings clearer, but since each pattern is formed as a thin film by sputtering method, it is possible to make the thermocouple pattern finer. It can absorb thermoelectromotive force. For example, in the structure shown in Figure 8, 5 m
When we created a thermoelectric element with 100 pairs of iron silicide thermocouples on an m-square substrate and measured its sensitivity, it was approximately 100 V/W.
Met. Further, even when the device was left at 700° C. for 1000 hours, there was no change in characteristics.

(g1 Effects of the Invention This invention produces a 1M thin film thermoelectric element that is small, highly sensitive, and has excellent heat resistance, so it can be applied to, for example, non-contact temperature sensors for automobile engines and blast furnaces, or thermal sensors. In addition, since a substrate containing impurities is not used during thin film formation, the impurity concentration of the semiconductor film can be easily controlled, and a thin film thermoelectric element with uniform characteristics can be obtained.

[Brief explanation of drawings]

FIGS. 1 to 7 are plan views showing the state on a substrate in each step of manufacturing a thin film thermoelectric element according to an embodiment of the present invention;
FIG. 8 is a plan view of the completed thin film thermoelectric element. ■One substrate, 2-Iron silicide thin film, 3.5.9-Mask, impurity (donor) film, impurity (acceptor) film, iron silicide n-type semiconductor film, iron silicide p-type semiconductor film, 0.11-Lead attachment terminal.

Claims (1)

[Claims] (1) A thin film thermocouple pattern formed by alternately arranging impurities as donors and acceptors and a thin film thermocouple pattern of an iron silicide film are respectively laminated on an insulating substrate, and heat treatment is performed to remove the impurities from the iron silicide film. A method of manufacturing a thin film thermoelectric element, comprising performing thermal diffusion to form a thermocouple pattern of an iron silicide n-type semiconductor film and an iron silicide p-type semiconductor film.