JPS58170086A - Thermocouple unit - Google Patents

Abstract

PURPOSE:To obtain a thermocouple unit which has high sensitivity by combining P type (N type) semiconductor and N type (P type) amorphous semiconductor having large thermocoupling capacity, large conductivity and different polarity of thermocoupling capacity. CONSTITUTION:In a thermocoupling unit 13, a P type (N type) thin amorphous semiconductor film 5 formed partly in contact with a P type (N type) diffused layer 3 forms a hot contact point 12, and ohmic electrodes 7, 8 form a cold contact point, and a DC thermal electromotive force Vth which is proportional to the temperature difference DELTAT between the hot contact point and the cold contact point is generated between the electrodes 7 and 8. The magnitude of the electromotive force Vth depends upon the thermocoupling capacity alphaP(N) of the layer 3, the thermocoupling capacity alpha'N(P) of the film 6 and the temperature difference DELTAT, thereby obtaining the power Vth not less than 0.65mV per temperature difference DELTAT=1 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention focuses on the large thermoelectric properties and microfabrication properties of crystalline semiconductors, and the three features of amorphous semiconductor thin films, namely (1) large thermoelectric properties, and (2) pm junction. This invention relates to a thermocouple device with a new structure that takes advantage of the characteristics of crystalline semiconductor and amorphous semiconductor thin films, focusing on (3) ease of thin film formation and microfabrication. In particular, the present invention relates to a power detection device for detecting power ranging from low frequencies to radiant waves (light waves) K, which is constructed by applying this thermocouple device.

Here, the amorphous semiconductor is a substance excluding liquid and gas, and refers to a semiconductor that does not exhibit crystallographic three-dimensional synchronization. That is, it is irregular, amorphous, and
Semiconductors that do not have diffraction peaks that can be identified in their line diffraction patterns are called semiconductors.

Traditionally, when measuring high frequency power, a bolometer has been used as a detection element, and recently, thin film thermocouple elements such as Group-8b and semiconductor thin film thermocouple elements such as 81-CIN have been used. There is.

The method that uses a bolometer such as a thermistor or barrette as a detection element measures the incident power indirectly from the change in resistance value that occurs when high-frequency energy is absorbed, and the resistance value is sensitive to changes in the surrounding temperature. The zero point fluctuates due to the change in , and a circuit to compensate for this zero point drift is required. Furthermore, in the case of a thermistor, the input standing wave ratio increases as the frequency increases, and in the case of a barrette, there are drawbacks such as vulnerability to overcurrent. In a method using a thin film thermocouple element or a semiconductor-thin film thermocouple element as a detection element, the thin-film thermocouple element or semiconductor-thin film thermoelectric element absorbs incident high-frequency power, and generates a direct current thermal wave proportional to the incident power. It is measured by converting it into electric power. This method is l
I6 Although the zero point drift due to changes in ambient temperature is small, l
Minute ′ below μW:・1 Bi at 0% where it is difficult to measure the power
When the vapor-deposited film V4 is applied to an insulating substrate such as -8b or mica, the adhesion to the substrate becomes weak. Moreover, since the quality of the 5''C film is damaged by water or organic solvents, there are drawbacks such as the inability to use microfabrication techniques such as photoetching technique IIK.On the other hand, semiconductors such as 81-T@mN The thin film thermocouple element has a support substrate with a thermal conductivity of approximately 1.4.
It is large at 5W/αC. Therefore, in order to increase the detection sensitivity of the thermocouple element, it is necessary to make the four substrates thinner, and in a practical element, the substrate thickness is bμm 1 degree. However, this semiconductor-thin film thermocouple element using 81-Tan N uses only one side of the large thermoelectric power of the p-type or talk-type semiconductor, and the polarities of the p-type and 3-type are opposite to each other. It has not yet been applied to a p-+a* combination type thermocouple element with a structure that makes effective use of the points. The reason for this is the rectifying property of the Sea 11 junction, and in order to eliminate the rectifying property, those with a structure in which a metal for ohmic electrodes is inserted between the p-*@ groups will cause the electromagnetic field distribution of the power to be measured to be Therefore, it was not used for high-frequency power detection scissors.

In view of the above points, the present invention provides 1. Focusing on the large thermoelectric properties of an amorphous semiconductor thin film (e.g. +7."7" The present invention aims to provide a high-performance thermocouple device with a new structure that makes effective use of thermoelectric properties and microfabricability, and a power detection device that applies this thermocouple device. Figures 1 and 2 show DC using a mixed gas of 81F and Ilm.
FIG. 3 is a diagram showing the thermoelectric conductivity characteristics and temperature difference-thermoelectromotive force characteristics of p-type and 1-type amorphous 81 thin films deposited on a glass substrate due to glow discharge properties. In Fig. 1, the circles indicate the characteristics of the flaky type, and the 0 marks indicate the P-type characteristics.

The thermoelectric power α is positive in the p-type and negative in the dynamic type. Doping gases for forming p-type and alpha-8i thin films include:
BsH@ and pus were used, respectively. As for the magnitude of thermoelectric power, the p-type shows an absolute value of more than 200 mol 7'Q. Figure 2 shows that metal electrodes are provided at both ends of the p-type and 111 mol 7 as S1 thin films, and the cold junction side is kept at room temperature. The figure shows the relationship between the thermoelectromotive force vtb and the temperature difference ATK between the hot junction and the cold junction (room temperature) when the hot clamping point is raised to a high temperature. In the drawing,
The solid line indicates the p-type, the dashed line indicates the n-type, the p-type indicates positive, and the 3-type indicates negative. Good linearity was obtained in both cases. From the above experimental results, it was found that amorphous semiconductor thin films, especially amorphous mother thin films, exhibit excellent properties as thermocouples and materials. 3 and 4 show the configuration of an embodiment of the thermoelectric device according to the present invention.
FIG. 4 shows a cross-sectional view along line xx'. In the drawing, 1 is a frame, 2 is a thin ya-type (p-type) semiconductor substrate, and 3
is a p-type (n-type) semiconductor diffusion layer, 4 is an insulating film, and 5 is a p-type (
n-type) amorphous semiconductor film, 642" type (p-type) ) Ohmic electrodes provided on the amorphous semiconductor thin film, 9 and 10 each lead wire provided on each ohmic electrode, 11 people, 11
B indicates a cold junction, 12 a hot junction, and 13 a thermocouple device.

This thermocouple device (13) has a p-type (n-type) diffusion layer (3)
A p-type (n-type) 7 mole 7 ass semiconductor thin 1K (61 parts form a hot junction (i2), and each ohmic conductor & (7, 8) parts form a cold junction Therefore, the DC thermoelectromotive force vtb (mV) proportional to the temperature difference ΔT (C) between the hot and cold junctions becomes an ohmic voltage &(7
) and the ohmic electrode (8). The magnitude of the thermoelectromotive force vtb generated at this time is the thermoelectric power αp (ml) of the p-type (II-type) semiconductor diffusion layer (3), the thermoelectric power αI of the n-type (p-type) amorphous semiconductor thin film (6), ( 1),
It is determined by the temperature difference 6 and is given by the following formula.

Vtb −(1114(nll +lα'n(111)
・ΔT... (1) From the experimental results shown in Figure 1 and the basic characteristics of semiconductors, cXp (m = 500 (-450
)fiV/C or more, (1'*Ipl=-160(200
') Since the above are obtained for μ■, the temperature difference Δ
A thermoelectromotive force vtb of 0.65 mV or more can be obtained per T-IU. p-type (m-type) semiconductor diffusion layer (3) and n% (p-type)
T-type or p-type (
The n-type (n-type) amorphous semiconductor thin film (5) is used to eliminate rectification that occurs when a pl-type (n-type) semiconductor and an n-type (p-type)' amorphous semiconductor thin film are bonded. The frame (1) keeps the temperature of the cold junction constant;
It has the function of holding the thin semiconductor substrate (2). The insulating film (4) provided on the inner thin three-type (ν-type) semiconductor substrate (2) is between the −-type (p-type) semiconductor and the n-type (p-type) amorphous semiconductor thin film (6). Although it is not necessarily necessary to provide the layer on the p-type (II-type) diffusion layer (3), this figure shows the case where it is provided.

When measuring the high wjj wave power P using this thermocouple device (13), the measured high frequency power PV is supplied between the leads 1 (QIO). At this time, the supplied high-frequency Vt force P is applied to the p-type (ca-type) semiconductor diffusion layer (3) and n'#/(
(p type) is absorbed by the amorphous semiconductor thin Ill (6) and generates Joule heat. The magnitude of the Joule heat generated at this time is proportional to the supplied high-frequency power P, so the hot junction Th (12') and the cold junction Terll.

The temperature difference ΔT between the ohmic electrodes ('lB) is caused by absorption and heat generation in the supplied high-frequency semiconductor diffusion layer to be measured (3) and the n-type (p-type) amorphous semiconductor thin film (6). DC thermoelectromotive force vth brought to
is given by the following equation.

Vth −(Iα−1+1α′m(dl)ΔTo((l
αpla)+I(fntpH)・P−(2) From equation (2), the magnitude P of the high-frequency power to be measured is determined by the thermocouple device (13
) is obtained by measuring the DC voltage between each ohmic electrode (z8).

When the measured power P is constant, the magnitude of the DC electromotive force obtained increases as the -F temperature rise of the hot junction increases, and the response speed depends on the thermal conductivity of the semiconductor substrate. Therefore, the shape is determined while taking into consideration the electrical conductivity of the p-type (Il-type) semiconductor diffusion layer (3) and the screen-shaped (p-type) amorphous semiconductor thin film (6) and the thermal conductivity of the semiconductor substrate.

In this case, it is necessary to reduce the shape of the heat generating part from within the impedance matching circuit and place it in the center of the semiconductor substrate, as well as to suppress the dissipation of the generated Joule heat, so the thickness of the semiconductor substrate is usually reduced. It has a thin shape of around 5 μm.

5 and 6 are diagrams showing an embodiment of an optical power detection device to which the present invention is applied; FIG. 5 shows a plan view, and FIG.
The figure shows a cross-sectional view taken along line x-f. In the drawing, 21 is 7
n is a thin state type (p type) semiconductor substrate, O is a p type (11 type) diffusion layer, 24 is an insulating film, 25 is a p type (n type)
Amorphous semiconductor thin film, grave is blind-shaped (p-type) amorphous semiconductor thin film, n, 28 are each ohmic electrode, 9.30
is each lead/wire.

31 is a light absorption film, an island, azs is a cold junction, 33 is a hot junction,
A indicates an optical power detection device. This optical power detection device is a hot junction (
33) p-type (type II) semiconductor forming p-type (blind type)
It has a structure in which a light absorption film (31) is provided on the amorphous semiconductor thin film bonding surface, and the light absorption film is composed of all black, carbon black, or amorphous semiconductor thin films with different composition ratios.

The thermocouple device and the optical power detection device applying the thermocouple device described in the above embodiments were each configured with a pair of thermocouple elements. It is possible to configure a multi-pair electrocouple device connected in a cascade and an optical power detection device applying them, and in this case, the output voltage (thermoelectromotive force) vth and output impedance between the ohmic electrodes are as follows.
Since the size of each thermocouple increases in proportion to the number of thermocouple elements, it is possible to design according to measurement accuracy, desired output impedance, etc.

Next, the manufacturing method will be described. Airfoil shape (P shape) V with a
t or G@Front semiconductor substrate (2) is coated with a p-type (circular) diffusion layer (3) and an insulating oxide a! using a normal IC process. (
4), a p-type (m-type) amorphous semiconductor thin film (5) and a dynamic (p-type) amorphous semiconductor (6) are deposited using a glow discharge method. For turning, photoetching technology or a metal mask is used. Next, a p-type (n-type) semiconductor diffusion layer and an n-type (p-type)
An ohmic electrode is provided on each part of the amorphous semiconductor thin film. The electrode materials are MU L, MU, and W, respectively.

NlCr, Pi, etc. are used. In particular, the electrode material for the 7th conductor thin film is NiCr 600 μm/A.
u1ooo;O The multilayer structure is excellent. Next, CVD8 is used as a protective film to cover the entire surface of the semiconductor substrate.
A 10m film, a CVD81sN+ film, a bolimide resin, etc. are used. Next, the protective film on the rad portion of the ohmic electrode is removed to form a lead wire pair (alO). The lead wire is constructed using the beam lead method or by wire bonding Aug or M1 ribbon wire, etc., but the beam lead method is superior.The central part of the back side of the semiconductor substrate is removed by chemical etching etc. and make it thinner. In this case, this is done so that a frame (1) can be formed around the periphery of the semiconductor substrate. These seven beams maintain the strength of the semiconductor substrate and also function as a heat sink. Here, a part of the semiconductor substrate was thinned by etching to leave a frame.
You can also learn how to attach a frame.

In the case of an 81 substrate with crystal orientation (1,0,0), a frame can be easily formed at the periphery by using an anisotropic etching solution. Finally, the device is completed by dividing it into chips using etching technology.

As a method for manufacturing the optical power detection device (34), light absorption is added to the method described in the method for manufacturing the thermocouple device. A glow discharge method, a vacuum evaporation method, or the like can be used to form the light absorption film. In addition, in the case of an optical power detection device, a p-type (dynamic type) amorphous semiconductor thin film inserted to eliminate the rectification property of a p-type (11 type) semiconductor-a-type (p-type) amorphous semiconductor thin film junction is used instead. Alternatively, a metal thin film exhibiting ohmic properties, such as a U/MU/NlCr structure, may be used. Next, we will briefly discuss the glow discharge method. Glow discharge methods include a DC glow discharge method in which a glow discharge is generated in a direct current electric field, and an RF daglow discharge method in which a glow discharge is generated in a high frequency electric field. Figure 7 is R
Using the F Douglow discharge method, amorphous S is deposited on the insulating substrate.
1 is an example of an apparatus for depositing a thin film. This device heats anodes and cathodes arranged in parallel between and within the vacuum chamber, an air supply port 42 and an exhaust port 8 for supplying or exhausting gas 41 into the vacuum container, and the anode and canard. It is composed of a heater 44 and the like. An insulating substrate is placed on the anode. The gas 41 is usually S.
%H6 or a mixed gas of 81F4 and H3 to which a doping gas (for example, PH, msH@*BBH, etc.) is added is used. The vacuum pressure during glow discharge is several To
rr.

The voltage is approximately constant, the current is 1 to 10 m) v'dl, and most of the gas reactions occur within the positive column (plasma 46). In particular, this glow discharge method has the characteristic of being able to deposit amorphous semiconductor thin films at low substrate temperatures of 400°C or less (conventional thermal decomposition methods for thin film production require a substrate temperature of 500 to 700°C). Ta). As an example of deposition conditions using the DC glow discharge method, discharge pressure OJ~Wte・rr, discharge current 1~Zoo y
*Iv'd1. Discharge voltage 500-800V.

Electrode spacing 3cIIL, substrate temperature 260-450C, 8
1F6/)I.

-1~10, BAH@/81F+ -100~2
500 ppm.

PH,/81F4=100-2500 ppm. As an amorphous semiconductor thin film deposited under these conditions, a conductivity of Cr"ta2D(Q-ca)' or higher can be easily obtained. Methods for increasing the conductivity of a semiconductor thin film include increasing the discharge current or doping. A common method is to increase the Ga10 ratio.Also, a method of applying a magnetic field is also effective.When a semiconductor thin film is deposited using the above method, a fine crystalline phase of around 100 A is formed in the amorphous film. , or exhibits polycrystalline properties, but retains thermoelectric properties.Furthermore, an alloy type amorphous semiconductor thin film of 8l-Go also has high conductivity.

In this case, a mixture of GeH4 and a doping gas of Ban5 or PH Tom sHB is used, and a DC glow discharge method (a method of applying a direct current voltage) or a method of applying a RF glow discharge pseudo-frequency voltage) is used. to deposit an amorphous semiconductor thin film.

Next, the effects of the present invention will be described.

(1) Highly sensitive thermoelectric sealing due to the combination of p-type (--type) semiconductor and cylindrical Cν-type) amorphous semiconductor with large thermoelectric power and conductivity and different polarities of thermoelectric power! and a high-frequency power detection element using this,
An optical power detection device can be configured.

(2) It is also possible to thin the semiconductor substrate in the area that will become the hot junction, form a p-type (T or n-type) semiconductor region over the entire thickness, and use that region as one element of the thermocouple configuration. A room is provided at the periphery of the semiconductor substrate to serve as a heat sink for the cold junction, increasing the efficiency of thermoelectric conversion and maintaining strength.

(3) Since microfabrication technology such as photo-etching technology can be used, it is possible to construct an ultra-small thermocouple device ship.

(4) When measuring high frequency power, especially power higher than microwave, high frequency power of p-type (n-type) semiconductor - p-type (morphology) amorphous semiconductor thin film - n-type (p-type) amorphous semiconductor thin film junction type structure In the detection element, the junction does not require a metal electrode for ohmic control, so the parasitic reactance is small, and as a result, the power product tts and tts with the manual standing wave ratio kept low, that is, up to the ultra-high frequency band. Can be used for power detection and snow making.

As described above, the thermocouple device according to the present invention can be applied in various ways to constitute a power detection device and an optical power detection device, and has many advantages over conventional devices in terms of performance and manufacturing method. Therefore, the industrial effect is large.

[Brief explanation of the drawings] Diagram m1 shows the thermoelectromotive force characteristics of p-type and n-type amorphous St semiconductor thin films; Diagram 2 shows the temperature difference-thermoelectromotive force of p-type and l-type amorphous St semiconductor thin films. Characteristic diagrams: Figures 3 and 4 are diagrams showing an embodiment of the thermocouple device according to the present invention. Figure 3 is a plan view, and Figure 4 is the x-
Figure 5 shows a cross-sectional view taken at the line X; Shape (p-type) semiconductor substrate at x-x' in Figure 5, 3.23 is p-type (n-type) semiconductor diffusion layer, 4.24 is insulating oxide film, 6.25 is p-type (n-type) amorphous Semiconductor thin film, 6.26 is the morphology (p
form) amorphous semiconductor thin film, ? , 8.27° public is each ohmic electrode, 9, 10, 29, 30 are each tightened by one dot,
IIA, IIB, 324, 32B are cold junctions, 12, 33 are hot junctions, 13 is thermoelectric sealing @, 1
4 to 20'! So, the missing number. 31 is a light absorption film, 34 is an optical power detection device, 35 to 3
Numbers up to 7 are missing, 39 is an anode, and 40 is a single pole (
cathode). Agent Patent Attorney Ryutabu Koike 2030,! 1060 △T″C Shooting 3 Figure 4th day

Claims (1)

[Scope of Claims] A thin cylindrical (p-type) semiconductor substrate (2) with seven rims (1) on the periphery; formed on a part of the surface of the semiconductor substrate;
A p-type (n-type) semiconductor spreader 1 scattered over the entire thickness of the substrate surface.
(3) and (4) an insulation II that partially covers the surface of the semiconductor substrate other than the semiconductor diffusion layer; (P type) second
amorphous semiconductor thin film II (61); a first electrode (7) ohmically connected to the i diffusion layer; a second electrode (7) ohmically connected to the amorphous semiconductor thin film of Mukuro *2;
8) and provision; by making the #Ll and the second electrode part negative 1 a cold junction, and making the first amorphous semiconductor ridge 12) a hot junction; A thermocouple device characterized in that a thermoelectromotive force is generated between the second electrodes.