JPH053896B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a heating element support structure suitable for a detection device requiring temperature control, and more specifically to a heating element support structure that reflects radiant heat dissipated from the heating element to the heating element. This invention relates to a heating element support structure that aims to utilize heat effectively. The heating element support structure of the present invention is applicable to any device that requires temperature control, such as a temperature sensor, humidity sensor, alcohol sensor, infrared sensor, flow rate sensor, sonic sensor, vacuum gauge, etc.

Prior Art Generally, in order to obtain highly reliable detection performance from a detection device using, for example, a metal oxide semiconductor as a detection sensor section, it is required to quickly and uniformly heat the detection sensor section to an appropriate temperature. For this reason, a method is used in which an electric heater as a heating means is installed in a bridge-like manner by extending it into the air together with the object to be heated, thereby increasing heating efficiency by preventing dissipation of the generated heat, mainly through conduction, as much as possible. There is. However, in order to stably obtain the desired temperature control effect with low power consumption suitable for battery operation, a more efficient heating method is required.

Purpose The present invention has been made in view of the above points, and an object of the present invention is to provide a heating element support structure that can stably obtain a desired temperature control effect with low power consumption.

Configuration In order to achieve the above object, the present invention is characterized by supporting a heating element in a space and having a reflective surface that reflects radiant heat from the heating element to the heating element. be.

Hereinafter, a specific explanation will be given based on one embodiment of the present invention. FIG. 1 is a plan view showing a gas detection device as an embodiment of the present invention, and FIG. 2 is a sectional view thereof. As shown in both figures, Si, Cu, Ni,
In this example, on the substantially square surface of the substrate 1 made of Cr, Al, Mo, W, NiCr, stainless steel, etc.,
An insulating film 2 made of Si ₃ N ₄ , SiO ₂ , etc. is deposited. A hemispherical recessed space 3 is formed in the center of the substrate 1. A bridge 4 made of an electrically insulating material is provided in this recessed space 3 in the form of a bridge. That is, the bridge 4 has a bridge structure that extends into the air. Bridge 4 in this example
is extended to pass through the center O of the spherical surface 3a of the recessed space 3 on the same plane as the insulating film 2.

The basic structure B consisting of the substrate 1, insulating film 2, and bridge 3 as described above can be easily formed integrally in the following manner. As the substrate 1, a material such as a Si wafer is used, which is easy to perform undercut etching and does not undergo deformation or deterioration at high temperatures (heating at 500° C. for several to 10 hours). First, an insulating film 2 is laminated on the entire surface of a substrate 1 to form a starting material before etching. Next, add the known NaOH or APM to this starting material.
Using an etchant such as (ethylenediamine, pyrocatechol, water), anisotropic etching is performed with different etching rates depending on the crystal orientation. As a result, as shown by the broken line in FIG. 3, the portion of the substrate 1 below the bridge portion 4 is undercut to form a polyhedral recessed space 3'a. Thereafter, by performing isotropic etching, the desired spherical surface 3a can be obtained. Isotropic etching is performed when the substrate 1 is
In the case of Si, this can be easily carried out using a known etchant such as (HF+HNO ₃ ). In this case, if the substrate 1 is made of Cu, Ni, Cr, Al, Mo, W, NiCr, stainless steel, etc., the spherical surface 3a can be obtained only by isotropic etching.

On the bridge 4, a pair of detection leads 5a,
5b are arranged with their respective ends facing each other at the center of the bridge ₄ (near the center O of the spherical surface _3a ) and separated by a predetermined distance _. A gas detection layer 6 made of a semiconductor material such as , ZnO and TiO ₂ is formed and defines a gas detection region. The gas detection layer 6 is provided in contact with the opposing ends of the detection leads 5a and 5b, and its resistance value changes due to gas adsorption.
Gas is detected by detecting the change. The detection leads 5a and 5b extend in opposite directions on the bridge 4, and are connected to respective electrode portions 7a and 7b provided via the insulating portion 2 at the upper right corner and lower left corner of the base B in the figure. are connected to each other. These electrode portions 7a, 7b are respectively connected to bonding pads 8a, 8b made of Au, Au alloy, or the like.

On the bridge 4, a pair of detection leads 5a,
A heater 9 is provided extending in parallel with 5b, and is connected to electrodes 10a and 10b adjacent to electrodes 7a and 7b of the detection leads. These heater electrodes 10a, 10b are similarly connected to bonding pads 11a, 11b. Then, the detection leads 5a, 5 except for the gas detection area are
b and the heater 9 are completely covered with a coating layer 12 made of an electrically insulating material, and the detection leads 5a, 5b and the heater 9 are electrically isolated on the bridge 4 by this coating layer 12. ing. As a result, leakage current between the leads can be minimized, and electromigration can also be actively prevented, thereby extending the life of each lead.

The spherical surface 3a formed in the recessed space 3 has a mirror surface even after the etching process, but in this example, a reflective film 13 made of Au is coated on the area except the bottom in order to further increase the reflection efficiency. has been done. This reflective film 13 can be easily formed by a method such as vacuum deposition or sputtering. In this case, heater electrodes 10a, 10b, detection lead electrodes 7a,
Au bonding pads 8a, 8b, 1 on 7b
It is advantageous to carry out the step at the same time as forming 1a and 11b because the number of steps can be reduced. Note that the pattern of the Au film can be easily formed using a vapor deposition mask, photolithography, or other means.

In the gas detection device configured as described above, preferably a pulsed current is applied to the heater 9 to generate heat in order to reduce power consumption, and the gas detection layer 6
uniformly heated to an appropriate temperature to lower its resistance and improve the accuracy of gas detection. In this case, the heat emitted from the heater 9 is conducted to the gas detection layer 6 via the bridge 4 etc. and is heated together with the heat, and is also radiated into the surrounding air as shown by the arrow. This radiant heat is efficiently reflected by the reflective film 13 attached to the spherical surface 3a, and the center O of the spherical surface 3a
are gathered near. Since the gas detection layer 6 is disposed near the center O of this spherical surface, the collected heat is used to heat the gas detection layer 6, and the gas detection layer 6 can be heated more efficiently. Therefore, desired temperature control can be performed efficiently with low power consumption, and highly reliable gas detection performance can be stably exhibited. In this example, the recessed space 3 is formed into a spherical shape, but the present invention is not limited to this. Similarly, the recessed space 3 can be formed into a parallelepiped shape by isotropic etching, and the detection lead 6 is arranged near the focal point. Even if it is installed, the same efficient temperature control effect can be achieved.

Next, some other embodiments of the present invention will be described. Incidentally, the same components as those in the above embodiment are given the same reference numerals, and the explanation thereof will be omitted.

The embodiment shown in FIG. 4 and its cross-sectional view in FIG. . Space 14 shaped like this
can be easily formed by using a Si wafer as the substrate 1 and by the above-mentioned known anisotropic etching process. In this case, the wall surface 14a has Si
(111) and (100) planes may be used for the bottom surface 14b. In addition, in order to efficiently collect the radiant heat from the heater 9 at the center Q of the bridge 4 where the object to be heated is placed, the dimensions of each part are a, b, c, and d.
may be set so that a=b, cd. Then, on the four wall surfaces 14a, a reflective film 15 made of Au is similarly applied.
is covered. Even when the concave space 14 is formed in a polyhedral shape as described above, the dissipated radiant heat from the heater 9 is reflected by the reflective film 15 and then collected in the central part Q, which is the area to be heated, efficiently bringing the heating target to the desired temperature. Can be heated quickly.

The embodiment shown in FIG. 6 is a preferred example for uniformizing the temperature distribution of the extending heating element itself to an appropriate temperature efficiently. An example of a device that requires such a heating element support structure is a catalytic combustion type gas sensor. The wider the range of variation, the larger the signal obtained. In FIG. 6, below the heater 16 extending on the bridge 4, there is a concave space 17 formed by combining two of the above-mentioned inverted quadrangular truncated pyramidal spaces, which is made of a Si wafer and is recessed in the base body B. There is. In this case, all the wall surfaces 17a are formed of (111) planes, but as shown in FIG.
The polyhedral recessed space 18 may be formed using two types of wall surfaces 18a, (111) and (211).

In this embodiment configured as described above, when the heater 16 is energized to generate heat, the center portion C reaches the highest temperature. However, in this example, the radiant heat from the central portion C reaches the recess wall surface 1 as shown by the arrow.
It is reflected at both ends by 7a and 18b and used for heating both ends of the heater. Therefore, an excessive temperature rise in the central portion is prevented, and the temperature distribution of the entire heater 16 is efficiently uniformized to an appropriate temperature. As a result, a large output signal with high reliability can be obtained, power consumption is reduced, and the durability of the device is improved. In this example, a pattern is formed by anisotropic etching as the recessed spaces 17 and 18, but this can also be done by combining isotropic etching.

In the embodiment shown in FIG. 8 and its sectional view, FIG. 9, the radiant heat dissipated upward from the heater 9 is also utilized by being reflected to the region to be heated. As shown in the figure, above the bridge 4, a second base body 20 is provided, in which a concave space 21 having substantially the same shape as the hemispherical concave space 3 recessed in the first base body 19 is provided.
1 and cover it. As a result, the bridge 4 and the heater 9, gas detection layer 6, etc. placed thereon are housed in the spherical dome space S. In order to prevent the temperature in the dome space S from rising excessively and impeding the heating temperature control effect of the heater 9, an appropriate number of air penetration portions 22 are provided along the first base surface 19a in this example. They are provided evenly around the space S. Moreover, the first base body 19 and the second base body 2
0 is bonded via a mounting layer 23 made of, for example, In or the like. In this embodiment configured as described above, the radiant heat dissipated upward from the heater 9 is also reflected onto the gas detection layer 6 and used, so that a more efficient heating effect on the gas detection layer 6 can be obtained. Note that this embodiment is not limited to this embodiment, and the concave spaces to be combined may have a polyhedral shape as shown in FIG. A dome type support structure can be applied.

Effects As detailed above, according to the present invention, the temperature distribution of the heating element can be efficiently controlled depending on the purpose of use by making the heating element emit and utilize the radiant heat dissipated from the heating element. Therefore, it is possible to obtain an efficient heating effect depending on the application with low power consumption, and it is also possible to improve the durability of the heating element. It should be noted that the present invention is not limited to the specific embodiments described above, and it goes without saying that various modifications can be made within the technical scope of the present invention.
For example, the heating element is not limited to an electric heater, but the present invention can be applied to various heating elements such as a heating element that utilizes a chemical reaction.

[Brief explanation of the drawing]

1 and 2 are a plan view and a sectional view showing one embodiment of the present invention, respectively, FIG. 3 is an explanatory diagram showing a manufacturing method of one embodiment of the present invention, and FIGS. 4 and 5 6 and 7 are respectively a plan view and a cross-sectional view showing a modified example of one embodiment of the present invention, FIGS.
9 are a perspective view and a sectional view, respectively, showing still another embodiment of the present invention. (Explanation of symbols), 1: Substrate, 3, 14, 17,
18, 21: recess space, 4: bridge, 9, 1
6: Heater.

Claims (1)

[Scope of Claims] 1. A substrate having at least an insulating surface portion is provided, at least a portion of the substrate is recessed from the surface to form a recess, and the insulating surface portion has a predetermined shape. It has a supporting part formed into a pattern in the shape of and projecting into the air above the recess, and a heating element is provided on the supporting part, and a reflective surface that reflects radiant heat from the heating element to the heating element. is defined by at least a portion of the recess. 2. The heating element support structure according to claim 1, wherein the recess is formed by etching a predetermined portion of the substrate. 3 In claim 1 or 2,
A heating element support structure, wherein the substrate is a non-insulating material, and the insulating surface portion is provided by depositing an insulating layer on the surface of the substrate. 4. A heating element support structure according to any one of claims 1 to 3, characterized in that a reflective film is provided at a predetermined location of the recess to define a reflective surface. 5. In any one of claims 1 to 4, the recess has an at least partially spherical shape, and the heating element is located substantially at the center of the spherical shape. A heating element support structure characterized in that the heating element support structure is located at a position. 6. The heating element support structure according to any one of claims 1 to 5, wherein the recess has an at least partially planar shape. 7. In any one of claims 1 to 5, the heating element has a heater made of a conductive material patterned in a predetermined shape on the support, and , a heating element support structure that generates heat by passing a current through the heater. 8. In any one of claims 1 to 7, a pair of leads are provided on the support body in parallel with the heater and spaced apart from each other by a predetermined distance, A heating element support structure characterized in that a gas detection layer made of a semiconductor material is provided connected between the leads of the heating element. 9. In any one of claims 1 to 8, a covering member is provided that is placed on the substrate and covers the heating element from above, and the covering member also covers the heating element. A heating element support structure characterized by being provided with a reflective surface that reflects radiant heat from the heating element to the heating element.