JP2002050801A - Thermoelectric conversion device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoelectric conversion device having a large output voltage, and its manufacturing method. SOLUTION: In a method for manufacturing a thermoelectric conversion device 1, the thermoelectric conversion device 1 is provided with a substrate 2 and a plurality of thermocouples 3 that are erected on the substrate 2 with an interval one another and are connected in series. The thermocouples 3 are formed in an L shape with a horizontal part 4 that is fixed onto the substrate 2, and a vertical part 5 where a base edge 5a is connected to a side end 4a of the horizontal part 4 so that it can be flexed freely. A glass layer 7 is formed on the substrate 2, and a plurality of thermocouples 3 that are composed of the horizontal part 4 and the vertical part 5 being connected so that they can be flexed freely via at least one-layer metal films 8 and 9 and are connected in series are formed in parallel with the substrate 2 on the glass layer 7, the glass layer 7 is removed while a specific range between the horizontal part 4 and the substrate 2 is left, and then the vertical part 5 is bent vertically to the substrate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an element which can be used as a power supply or an auxiliary power supply for an electronic device, a temperature sensor, an infrared sensor, or the like. The present invention relates to a thermoelectric conversion device used and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a conventional thermoelectric element of this type, for example, as shown in FIG. 18, a prismatic n-type thermoelectric semiconductor element 20 and a p-type thermoelectric semiconductor element 20 are regularly arranged alternately in rows. There is known a thermoelectric element block 23 in which the element pieces 21 are integrated with an insulator 22 (see Japanese Patent Application Laid-Open No. 63-20880).

[0003] Electrodes are formed on the upper surface 23c and the lower surface 23d of the thermoelectric element block 23 by vapor deposition or the like, and the n-type thermoelectric semiconductor pieces 20 and the p-type thermoelectric semiconductor pieces 21 are alternately connected in series.

[0004]

However, in the above-described thermoelectric element block 23, the insulator 2 is formed around the n-type thermoelectric semiconductor element 20 and the p-type thermoelectric semiconductor element 21.
2 and there is a problem that the output voltage is small because the temperature difference between the upper contact 23cc side contact and the lower contact 23d side contact is small.

[0005] The present invention has been made in view of the above problems, and has as its object to provide a thermoelectric conversion device having a large output voltage and a method of manufacturing the same.

[0006]

According to a first aspect of the present invention, there is provided a thermoelectric conversion device comprising: a substrate; and a plurality of the substrates, which are erected on the substrate at an interval from each other and connected in series. And a thermocouple.

According to a second aspect of the present invention, the thermocouple is formed in an L-shape from a horizontal portion fixed on the substrate and a vertical portion having a base end flexibly connected to a side end of the horizontal portion. It was done.

According to a third aspect of the present invention, the horizontal portion and the vertical portion are connected by at least one metal film.

According to a fourth aspect of the present invention, a top plate opposed to the substrate is provided at the tips of the plurality of thermocouples.

According to a fifth aspect of the present invention, one thermoelectric material constituting the thermocouple is made of a semiconductor, and the other thermoelectric material is made of a metal.

According to a sixth aspect of the present invention, which relates to a method of manufacturing a thermoelectric conversion device, a glass layer is formed on a substrate, and the glass layer is flexibly connected to the glass layer via at least one metal film. A plurality of thermocouples composed of a horizontal portion and a vertical portion and connected in series are formed in parallel with the substrate, and the glass layer is removed while leaving a predetermined range between the horizontal portion and the substrate. Then, the vertical portions are respectively bent perpendicularly to the substrate.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 to 3, the thermoelectric conversion device 1 according to this embodiment includes, for example, a substrate 2
And a plurality of thermocouples 3 erected at an interval from each other so as to form an array structure on the substrate 2 and connected in series. The thermocouple 3 is fixed to a horizontal portion fixed on the substrate 2. 4
And a vertical portion 5 having a base end 5a flexibly connected to a side end 4a of the horizontal portion 4 in an L-shape.

The substrate 2 is made of, for example, ceramics, glass,
It is composed of silicon or the like, and if necessary, a silicon nitride (Si ₃ N ₄ ) layer or a silicon oxide (SiO ₂ ) layer (electrical)
An insulating layer 6 and the like are formed.

The thermocouple 3 is connected to the horizontal portion 4 and the vertical portion 5 by L
It is formed in the shape of a letter. The horizontal portion 4 is fixed on the substrate 2 via an insulating layer 6 and a glass layer 7 made of phosphorus glass or the like formed in a predetermined range on the insulating layer 6. The base end 5a of the vertical portion 5 is connected to the side end 4a of the horizontal portion 4 via, for example, two layers of metal films 8 and 9 so as to be freely bent.

The material of the metal film 8 is, for example, Cr
The material of the metal film 9 is, for example, Au.
The metal films 8 and 9 are not limited to two layers, and may be one layer or three or more layers. The material of the horizontal portion 4 and the vertical portion 5 includes various semiconductors and metals.
And the vertical portion 5 may be integrally formed of at least one metal film 8,9.

The horizontal portion 4 is composed of horizontal portions 10a and 11a of two thermoelectric materials 10 and 11 arranged at an interval. Each of the horizontal portions 10a and 11a includes a base layer 12 formed on the glass layer 7 and metal films 8 and 9 formed in a predetermined range on the base layer 12. Adjacent thermocouples 3 are connected in series by integrally forming the base layer 12 and the metal films 8 and 9. The material of the base layer 12 is, for example, polycrystalline silicon.

The vertical portion 5 is composed of vertical portions 10b and 11b of two thermoelectric materials 10 and 11. One vertical portion 10b is composed of the base layer 12 and metal films 8, 9 formed on the side surface of the base layer 12 near the base end 5a of the vertical portion 5. The other vertical portion 11b is
And metal films 8, 9 formed on the entire side surfaces of the base layer 12.
It is composed of Two vertical parts 10b, 11b
Are connected by integrally forming the base layer 12 and the metal films 8 and 9 at the tip 5b of the vertical portion 5.
Further, the metal films 8, 9 of the vertical portions 10b, 11b and the metal films 8, 9 of the horizontal portions 10a, 11a are also integrally formed,
The horizontal portion 4 and the vertical portion 5 are flexibly connected to each other via the metal films 8 and 9 that are ductile materials. Therefore, as described later, there is an advantage that the vertical portion 5 can be bent perpendicularly from a state where the vertical portion 5 is formed parallel to the substrate 2 and there is almost no breakage at the time of bending.

The thermoelectric conversion device 1 configured as described above
Either the substrate 2 side or the distal end 5b of the thermocouple 3 functions as a hot junction and the other functions as a cold junction, but since there is nothing around the thermocouple 3, the temperature of the hot junction and the cold junction There is an advantage that the difference is large and the output voltage is also large.
The thermoelectric conversion device 1 includes, for example, power generation by industrial waste heat, power generation by heat of automobile exhaust gas, power generation by substrate heat radiation of an electronic device such as a personal computer, power generation by body temperature of a wristwatch, and a temperature sensor or an infrared sensor. It can be used for various purposes such as.

If a top plate 13 facing the substrate 2 is provided at the tips 5b of the plurality of thermocouples 3 as in this embodiment, the thermocouple 3 can be protected and the top plate 13 side can be protected. When used as a hot junction, there is an advantage that the top plate 13 can also be used as a heat absorber. Note that examples of the material of the top plate 13 include various semiconductors and metals.

Next, a method of manufacturing the thermoelectric conversion device 1 configured as described above will be described in the order of steps. (A) As shown in FIG. 4 and FIG.
If necessary, an insulating layer 6 or the like is formed by LPCVD (low pressu
re chemical vapor deposition) or the like. (B) As shown in FIG. 6, a glass layer 7
PCVD (atmosphericpressure chemical vapor depos
ition). (C) As shown in FIG. 7, the base layer 12 is
It is formed by PCVD or the like. (D) As shown in FIG. 8, a glass layer 14 is formed on the base layer 12 by APCVD or the like, and the base layer 12 is doped with impurities through the glass layer 14. (E) As shown in FIGS. 9 and 10, RIE (reactive
The base layer 12 is formed in a predetermined pattern by ion etching or the like. In this case, the bending groove 15 is formed along the arrangement direction of the thermocouples 3. (F) After depositing the metal film 8 on the entire surface, as shown in FIGS. 11 and 12, the metal film 8 is formed in a predetermined pattern by wet etching or the like. In this case, the metal film 8 is bridged above the bending groove 15. Similarly, as shown in FIGS. 13 and 14,
A metal film 9 is laminated on the metal film 8.

By the above operation, a plurality of thermocouples 3 composed of the horizontal portion 4 and the vertical portion 5 which are flexibly connected to the glass layer 7 via the metal films 8 and 9 and which are connected in series.
Are formed parallel to the substrate 2.

(G) As shown in FIGS. 15 and 16, the glass layer 7 is left while leaving a predetermined range between the horizontal portion 4 and the insulating layer 6.
Is removed (released) by the methanol replacement method, etc.
The vertical portions 5 are bent perpendicularly to the substrate 2 respectively.

The above-described top plate 1 is attached to the tips 5b of the plurality of thermocouples 3.
In the case where the thermocouple 3 is provided, the periphery of the thermocouple 3 is further filled with a resist or the like, and an appropriate semiconductor or metal or the like is deposited thereon to form a top plate 13 and then the resist or the like is removed by etching or the like. I just need.

As described above, according to the above-described manufacturing method, since an electronic device mounting technique such as photolithography can be used, there is an advantage that the integration density can be improved as compared with a conventional product.

[0025]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

A thermoelectric conversion device before release was manufactured in the same manner as in the above-described embodiment. For this production, MICS (Micromachine Integrated Chip Servic) of the Institute of Electrical Engineers of Japan, which conducts joint trial production of a three-layer polycrystalline silicon structure.
e) was used. Use a silicon substrate as the substrate,
An insulating layer was formed thereon. The glass layer was made of phosphorus glass, the base layer was made of polycrystalline silicon, the metal film on the base layer was made of Cr, and the second metal film was made of Au.

HF wet etching, NH ₄ F cleaning,
After removing (release) the glass layer leaving a predetermined range between the horizontal part and the substrate in the above-described thermoelectric conversion device by a methanol replacement method in which hydrophobic treatment, methanol washing, and baking are sequentially performed, the vertical part is removed from the substrate. To each other.

Before the release, the output voltage of the thermoelectric conversion device was measured using an electric heater having a tip of about 360 ° C. as a heat source and using the tip of the thermocouple as a hot junction. The result is shown in FIG. The calculated value in FIG.
It was calculated using the equation (2) and the physical property values of the literature.
Nobuhiro: Heat transfer engineering, Morikita Publishing (1988), pp.1-175. R, Le
nggenhager: CMOS Thermoelectric Infrared Sensors,
ETH Zurich (1994). The Japan Society of Thermophysical Properties: Thermophysical Properties Handbook, Table B-2-1, Yokendo (1990)]. For the Seebeck coefficient of the composite film made of polycrystalline silicon, Cr, and Au, the value of Au was adopted. V = N (α ₁ −α ₂ ) ΔT (1) ΔT = P _abs / G _T (2) where V (V): output voltage N: thermocouple Number α ₁ (V / K) _, α ₂ (V / K): Seebeck coefficient of each thermoelectric material ΔT (K): Temperature difference between hot junction and cold junction _Pabs (W): Absorbed energy G _T ( W / K): Total thermal conductivity coefficient of thermocouple

[0029]

As described above, according to the first aspect of the present invention, since nothing exists around the thermocouple, the temperature difference between the hot junction and the cold junction is large, and the output voltage is large.

According to the second aspect of the present invention, since the thermocouple is formed in an L-shape from the horizontal portion and the vertical portion, the thermocouple can be bent vertically from a state where the vertical portion is formed parallel to the substrate.

According to the third aspect of the present invention, since the horizontal portion and the vertical portion are connected by at least one metal film, there is almost no damage when the vertical portion is bent.

According to the fourth aspect of the present invention, since the top plate is provided at the tips of the plurality of thermocouples, the thermocouple can be protected, and when the top plate side is used as a hot junction, the top plate is heated. It can also be used as an absorber.

According to the fifth aspect of the present invention, one thermoelectric material constituting the thermocouple is made of a semiconductor such as polycrystalline silicon, and the other thermoelectric material is made of a metal such as Au or Cr. An unprecedented new thermoelectric conversion device can be provided.

According to the sixth aspect of the present invention, the glass layer is removed while leaving a predetermined range between the horizontal portion and the substrate, and then the vertical portions are respectively bent perpendicularly to the substrate.
Electronic device mounting techniques such as photolithography can be used. Therefore, the integration density can be improved as compared with the conventional product.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of a thermoelectric conversion device according to an embodiment.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is an enlarged sectional view of a main part of a substrate.

FIG. 5 is an enlarged sectional view of a main part showing a state where an insulating layer is formed on a substrate.

FIG. 6 is an enlarged sectional view of a main part showing a state where a glass layer is formed on an insulating layer.

FIG. 7 is an enlarged sectional view of a main part showing a state where a base layer is formed on a glass layer.

FIG. 8 is an enlarged sectional view of a main part showing a state where a glass layer is formed on a base layer.

FIG. 9 is an enlarged sectional view of a main part showing a state where a base layer is formed in a predetermined pattern.

FIG. 10 is a plan view of FIG. 9;

FIG. 11 is an enlarged sectional view of a main part showing a state where a metal film on a base layer is formed in a predetermined pattern.

FIG. 12 is a plan view of FIG. 11;

FIG. 13 is an enlarged sectional view of a main part showing a state where a second metal film is stacked on the metal film.

FIG. 14 is a plan view of FIG. 13;

FIG. 15 is an enlarged cross-sectional view of a main part showing a state where a glass layer is removed (released) while leaving a predetermined range between a horizontal portion and an insulating layer.

FIG. 16 is an enlarged sectional view of a main part showing a state where a vertical part is bent perpendicularly to a substrate.

FIG. 17 is a graph showing a relationship between a distance to a heat source and an output voltage in the example.

FIG. 18 is an enlarged perspective view of a main part in which a part of the conventional example is omitted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermoelectric conversion device 2 Substrate 3 Thermocouple 4 Horizontal part 4a Side end 5 Vertical part 5a Base end 5b Tip 7 Glass layer 8, 9 Metal film 10, 11 Thermoelectric material 13 Top plate

Claims (6)

[Claims] 1. A thermoelectric conversion device comprising: a substrate; and a plurality of thermocouples which are erected on the substrate at an interval from each other and connected in series. 2. The thermocouple according to claim 1, wherein said thermocouple is formed in an L-shape from a horizontal portion fixed on said substrate and a vertical portion having a base end connected to a side end of said horizontal portion so as to be freely bent. Thermoelectric conversion device. 3. The thermoelectric conversion device according to claim 2, wherein said horizontal portion and said vertical portion are connected by at least one metal film. 4. The thermoelectric conversion device according to claim 1, wherein a top plate facing the substrate is provided at a tip of the plurality of thermocouples. 5. The thermoelectric conversion device according to claim 1, wherein one thermoelectric material constituting the thermocouple is made of a semiconductor, and the other thermoelectric material is made of a metal. 6. A glass layer is formed on a substrate, and a horizontal portion and a vertical portion are connected on the glass layer so as to be freely bent via at least one metal film, and are connected in series. A plurality of thermocouples are formed in parallel with the substrate, and after removing the glass layer leaving a predetermined range between the horizontal portion and the substrate, the vertical portions are respectively perpendicular to the substrate. A method for manufacturing a thermoelectric conversion device, comprising bending.