JPH085452A - Infrared ray detecting element - Google Patents

Abstract

PURPOSE:To obtain an element, which can be easily manufactured and downsized and which has a wide angle of view field and the excellent responsiveness by forming an infrared ray detecting unit and an infrared ray transmitting filter on one surface of a substrate so as to be vertically overlapped, and forming a heat separation space under them. CONSTITUTION:An infrared ray detecting unit 2 is formed by overlapping a thin film resistor 2b and an infrared ray absorbing film 2c in order on a pair of electrodes 2a on an insulating film 4 of a semi-conductor substrate 1. An infrared ray transmitting film 3 is provided on the detecting unit 2 so as to be overlapped, and cuts the electromagnetic wave except for the infrared ray and transmits the only infrared ray. At the time of manufacturing an element, a lower part of a substrate 1, in which a detecting unit 2 is to be provided, is eliminated by the anisotropic etching so as to form a heat separation space 5. Thereafter, an electrode 2a is formed on the insulating film 4 over the space 5, and a resistor 2b and an absorbing film 2c are formed on the electrode 2a by deposition, and a filter is formed on the film 2c by deposition. Change of the resistance value of the resistor 2b is detected through a signal processing circuit 6 connected to the electrode 2a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared detecting element of a type which detects infrared rays by utilizing a change in electric resistance of a resistor due to a temperature change due to absorption of infrared rays.

[0002]

2. Description of the Related Art In detecting infrared rays, an infrared transmitting filter for blocking electromagnetic waves other than infrared rays is used together with the infrared detecting section in order to increase the sensitivity of detecting weak infrared rays. Here, conventionally, the infrared detection section and the infrared transmission filter were generally manufactured separately and assembled by aligning their optical axes. That is, FIG. 7 shows an example of the conventional example, in which an infrared detecting chip 21 having an infrared detecting portion such as a thermistor is attached to the stem 20, and above the chip 21,
The infrared transmission filter 3e, which allows only infrared rays to pass and blocks unnecessary wavelength components that become noise, is attached to the cap 22.
It is held and placed in.

[0003]

However, in the above-mentioned conventional one, the infrared transmission filter 3e is attached to the cap 22.
Cut into a fine shape that matches the shape of the opening 23 of
It is necessary to attach this to the opening 23 of the cap 22 with an adhesive, and the number of assembling steps increases, resulting in a high manufacturing cost. Further, in the above conventional one,
Due to restrictions on the assembly workability of each component and the like, the infrared transmission filter 3e and the infrared detection chip 21 need to be separated from each other to some extent. there were. As a means for solving these drawbacks, it is conceivable to directly superimpose the infrared transmission filter 3e on the surface of the infrared detection chip 21. However, in the above-mentioned conventional structure, the infrared detection chip 2 can be obtained by simply superposing them.
In addition to the heat absorption from 1 to the stem 20 side, heat absorption from the infrared detection chip 21 to the infrared transmission filter 3e is also added, so the infrared detection chip 21 corresponding to the infrared absorption.
The temperature change becomes slower, and the infrared detection sensitivity decreases. In addition, there is a problem that the responsiveness is further deteriorated due to the increase in the apparent heat capacity of the entire infrared detection site. Therefore, it is an object of the present invention to provide an infrared detecting element which can be manufactured easily and compactly, can secure a wide viewing angle, and is excellent in responsiveness of infrared detection.

[0004]

The infrared detecting element according to the present invention, which has been proposed to achieve the above object, is formed by superposing an infrared detecting portion and an infrared transmitting filter on one surface of a substrate, Below the infrared detecting section, a thermal separation space section for suppressing heat conduction between the infrared detecting section and the substrate is formed.

[0005]

In the infrared detecting element having the above structure, the infrared detecting section and the substrate are thermally separated by the heat separating space, so that the heat conduction from the infrared detecting section to the substrate is suppressed, and the infrared detecting section is also suppressed. The apparent heat capacity in the entire position of is small. Therefore, in the present invention, the infrared transmission filter is formed on the infrared detection unit, and despite the occurrence of heat conduction from the infrared detection unit to the infrared transmission filter, a decrease in the responsivity of infrared sensing due to the heat conduction occurs. This can be sufficiently compensated for by the heat separation between the infrared detecting section and the substrate, and eventually the infrared detection sensitivity and response of the infrared detecting section can be improved. Further, since the infrared transmitting filter is formed on the infrared detecting portion, a wide viewing angle is secured in the infrared detecting portion, and further, a cap or the like for supporting the infrared transmitting filter is not necessary at all.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a perspective view of an infrared detection element A according to the present invention, FIG. 2 is a plan view showing a structure of an electrode in an infrared detection section, and FIG. 3 is a sectional view showing a manufacturing process. The infrared detection element A is formed on the surface of the semiconductor substrate 1 made of silicon,
The infrared detecting section 2 and the infrared transmitting filter 3 are formed in an overlapping manner. Here, on the surface of the semiconductor substrate 1,
An insulating film 4 made of a silicon oxide film or a multilayer film of silicon oxide and silicon nitride is formed. Further, a part of the back surface side of the semiconductor substrate 1 located below the infrared detecting portion 2 is provided with a heat separation space portion 5 formed in a desired notched concave shape by etching or the like.

The infrared detecting section 2 is constructed by sequentially stacking a thin film resistor 2b and an infrared absorbing film 2c on a pair of electrodes 2a, 2a on the insulating film 4 of the semiconductor substrate 1. Of these, the thin film resistor 2b is made of, for example, amorphous silicon or polycrystalline silicon having a film thickness of 0.1 to 5.0 μm, and its resistance value changes with temperature change due to infrared absorption. The thin film resistor 2b includes both a resistor whose resistance value increases and a resistor whose resistance value decreases as the temperature rises, and any type may be used in the present invention.
The infrared absorption film 2c is formed of a material having a high infrared absorption rate and suitable for a semiconductor process. For example, silicon oxide can be applied, and gold black or the like can also be used. The infrared absorption film 2c also serves as a protective film for the thin film resistor 2b. The electrodes 2a and 2a are formed in a comb-shaped planar shape facing each other as shown in FIG. 2 so as to have a large area with the thin film resistor 2b so that a change in the resistance value of the thin film resistor 2b can be accurately detected. It is configured so as to make contact, and each end thereof is connected to a signal processing circuit 6 described later. Electrodes 2a, 2a
Can be formed by a thin film, but the material is A
Other than usual electrode materials such as u and Al, Ti, Zr, V, N
When a metal alloy such as b, Ta, Cr, Mo, W, Ni, Pt, or Pd, or a silicide with polycrystalline silicon is used, the infrared absorption rate is high, and thus the detection sensitivity can be improved. The electrodes 2a, 2a and the thin film resistor 2
The positional relationship upside down with b may be sufficient. The infrared transmission filter 3 blocks electromagnetic waves other than infrared rays and allows only infrared rays to pass therethrough. For example, a multilayer film of magnesium oxide having a high refractive index and magnesium fluoride having a low refractive index is applied. The infrared transmission filter 3 is provided so as to overlap the infrared detection unit 2. On the other hand, the semiconductor substrate 1
In the other part, a signal processing circuit 6 including an amplifier circuit and other circuits similar to those of a normal infrared detection device is formed below the insulating film 4, and the signal processing circuit 6 includes the electrode 2a, Each end of 2a is connected while passing through the insulating film 4.

In manufacturing the infrared detecting element A having the above structure, first, as shown in FIG. 3A, after the signal processing circuit 6 is manufactured on the semiconductor substrate 1 by a method according to a normal semiconductor process, An insulating film 4 is formed on the surface of the semiconductor substrate 1. Next, as shown in FIG. 2B, a portion of the semiconductor substrate 1 below the planned position where the infrared detecting portion 2 is provided is removed by anisotropic etching or the like to form the heat separation space portion 5. After that, as shown in FIG. 3C, electrodes 2a and 2a are formed on the insulating film 4 above the heat separation space 5, and a thin film resistor 2b and an infrared absorbing film 2c are formed thereon. It may be formed by vapor deposition or the like, and the infrared transmission filter 3 may be further formed thereon by the same vapor deposition means or the like.

In the infrared detecting element A having the above-mentioned structure, the infrared detecting section 2 and the infrared transmitting filter 3 are provided on one side of the semiconductor substrate 1.
It is configured as an integrated semiconductor chip, etc., and the size thereof can be made extremely small. Then, in use thereof, of the light rays incident from above the semiconductor substrate 1, only infrared rays can be transmitted through the infrared transmission filter 3 to be absorbed by the infrared detection section 2, and the thin film resistor 2b of the infrared detection section 2 can be absorbed. Change the resistance value to electrode 2
It can be detected through the signal processing circuit 6 connected to a and 2a. The infrared transmission filter 3 is the infrared detection unit 2
Since it is provided on top of the other, the viewing angle is wide. Thus, in the above-mentioned configuration, heat conduction occurs from the infrared detecting sections 2 superposed on each other to the infrared transmitting filter 3, but from the infrared detecting section 2 causing a much larger heat dissipation to the semiconductor substrate 1. Since the heat conduction of the heat is suppressed by the heat separation space portion 5, the heat conduction amount from the infrared detection portion 2 to the infrared transmission filter 3 becomes extremely small in total, and the infrared detection by the infrared absorption is performed. It does not cause a great obstacle to the temperature change of the part 2. Further, since the heat detecting space 5 thermally separates the infrared detecting section 2 and the infrared transmitting filter 3 from the semiconductor substrate 1, the apparent heat capacity of the entire infrared detecting section 2 is reduced. Therefore, in the end, the infrared detecting section 2 carries out a quick temperature corresponding to the infrared absorption, so that the response speed of infrared detection can be improved and the response performance can be made very excellent. Since the semiconductor substrate 1 is provided with the signal processing circuit 6, the signal processing circuit 6 is integrated in one chip together with the infrared detecting section 2 and the like, which is convenient for handling and a series of the infrared detecting section 2 and the like. In the manufacturing process, the signal processing circuit 6 can be manufactured efficiently. Moreover, since the wiring distance between the infrared detecting section 2 and the signal processing circuit 6 can be shortened, signal attenuation and noise intrusion can be reduced, and the infrared detecting performance can be further improved.

FIG. 4 is a perspective view showing an infrared detecting element Aa according to another embodiment of the present invention, and FIG. 5 is a cross-sectional view of a main part thereof (however, the same parts as those in the embodiments shown in FIGS. The same reference numerals are used). The infrared detection element Aa is provided with a plurality of slits (holes) 7 at predetermined positions of the insulating film 4 on the surface of the semiconductor substrate 1 and injects an etching solution from the slits 7, thereby making it possible to remove one side of the surface of the semiconductor substrate 1. The portion is removed to form the heat separation space portion 5a. Further, the slit 7 may be formed such that its planar shape is like a cantilever, as shown in FIG. 6, for example. In the present invention, even when the thermal separation space 5a is formed by using the slit 7 as described above, the heat conduction between the infrared detection unit 2 and the semiconductor substrate 1 can be suppressed, and Similarly, the response of infrared detection can be improved. In the infrared detection element Aa, the upper and lower electrodes 2a, 2
Although the thin film resistor 2b is sandwiched by a, the electrode structure may be used.

[0011]

As described above, according to the infrared detecting element according to the present invention, since the infrared transmitting filter is formed on the infrared detecting portion provided on the surface of the substrate, a large number of these portions are provided as in the conventional case. There is no need to assemble in a complicated structure using the parts of the above, the whole can be made small by simple manufacturing means, and a wide viewing angle of infrared detection can be secured, while the formation of the heat separation space part makes infrared It is possible to suppress heat conduction from the detection section to the substrate, reduce the apparent heat capacity of the infrared detection section, and improve the response performance of infrared detection.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of an infrared detection element according to the present invention.

FIG. 2 is a plan view showing an example of the configuration of electrodes of the infrared detection element according to the present invention.

FIG. 3 is a cross-sectional view showing an example of a manufacturing process of the infrared detection element according to the present invention.

FIG. 4 is a perspective view showing another embodiment of the infrared detection element according to the present invention.

FIG. 5 is a cross-sectional view of a main part of another embodiment of the infrared detection element according to the present invention.

FIG. 6 is a plan view of a main portion showing another example of a slit for forming a heat separation space.

FIG. 7 is a cross-sectional view of essential parts showing an example of a conventional infrared detection device.

[Explanation of symbols]

 1 Semiconductor Substrate 2 Infrared Detector 2a Electrode 2b Thin Film Resistor 2c Infrared Absorbing Film 3 Infrared Transmission Filter 4 Insulating Film 5, 5a Thermal Separation Space 6 Signal Processor 7 Slit A, Aa Infrared Detector

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[Procedure amendment]

[Submission date] March 3, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

[0003]

However, in the above-mentioned conventional one, the infrared transmission filter 3e is attached to the cap 22.
Cut into a fine shape that matches the shape of the opening 23 of
It is necessary to attach this to the opening 23 of the cap 22 with an adhesive, and the number of assembling steps increases, resulting in a high manufacturing cost. Further, in the above conventional one,
Due to restrictions on the assembly workability of each component and the like, the infrared transmission filter 3e and the infrared detection chip 21 need to be separated from each other to some extent. there were. As a means for solving these drawbacks, it is conceivable to directly superimpose the infrared transmission filter 3e on the surface of the infrared detection chip 21. However, in the above-mentioned conventional structure, the infrared detection chip 2 can be obtained by simply superposing them.
As other heat conduction from 1 to stem 20 side, in order from the infrared detecting chip 21 applied the thermal conduction to the infrared transmission filter 3e, the infrared detection chip 21 according to the infrared absorption
The temperature change becomes slower, and the infrared detection sensitivity decreases. In addition, there is a problem that the responsiveness is further deteriorated due to the increase in the apparent heat capacity of the entire infrared detection site. Therefore, it is an object of the present invention to provide an infrared detecting element which can be manufactured easily and compactly, can secure a wide viewing angle, and is excellent in responsiveness of infrared detection.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

In the infrared detecting element A having the above-mentioned structure, the infrared detecting section 2 and the infrared transmitting filter 3 are provided on one side of the semiconductor substrate 1.
It is configured as an integrated semiconductor chip, etc., and the size thereof can be made extremely small. Then, in use thereof, of the light rays incident from above the semiconductor substrate 1, only infrared rays can be transmitted through the infrared transmission filter 3 to be absorbed by the infrared detection section 2, and the thin film resistor 2b of the infrared detection section 2 can be absorbed. Change the resistance value to electrode 2
It can be detected through the signal processing circuit 6 connected to a and 2a. The infrared transmission filter 3 is the infrared detection unit 2
Since it is provided on top of the other, the viewing angle is wide. Thus, in the above-mentioned configuration, heat conduction occurs from the infrared detecting sections 2 superposed on each other to the infrared transmitting filter 3, but from the infrared detecting section 2 causing a much larger heat dissipation to the semiconductor substrate 1. Since the heat conduction of the above is suppressed by the heat separation space portion 5, the heat conduction amount from the infrared detection portion 2 to the infrared transmission filter 3 becomes extremely small in total, and the infrared detection by the infrared absorption is performed. It does not cause a great obstacle to the temperature change of the part 2. In addition, since the thermal detection space 5 thermally separates the infrared detection section 2 and the infrared transmission filter 3 from the semiconductor substrate 1, the apparent thermal capacity of the entire infrared detection section 2 is reduced. Therefore, in the end, the infrared detecting section 2 quickly raises the temperature corresponding to the infrared absorption, and the infrared detecting response speed can be improved,
The response performance can be made extremely excellent. By providing the signal processing circuit 6 on the semiconductor substrate 1, the signal processing circuit 6 is integrated together with the infrared detecting section 2 and the like in one chip, which is convenient for handling, and the infrared detecting section 2 is also provided.
The signal processing circuit 6 can be efficiently manufactured in a series of manufacturing processes such as. Moreover, since the wiring distance between the infrared detecting section 2 and the signal processing circuit 6 can be shortened, signal attenuation and noise intrusion can be reduced, and the infrared detecting performance can be further improved.

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

[Figure 5]

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Added

[Correction content]

[Figure 6]

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Added

[Correction content]

[Figure 7]

Claims (1)

[Claims] 1. An infrared detecting section and an infrared transmitting filter are formed on one surface of a substrate by stacking the infrared detecting section and the infrared transmitting filter vertically, and heat conduction between the infrared detecting section and the substrate is suppressed below the infrared detecting section. An infrared detecting element, characterized in that a heat separation space part is formed.