JPH05118909A - Infrared ray detecting element - Google Patents

Abstract

PURPOSE:To provide an infrared ray detection element capable of being manufactured easily in a compact size, having an excellent responsiveness for the detection of infrared ray, and providing no inconvenience of usage with a required lense set outside. CONSTITUTION:An infrared ray detection element is provided with an infrared ray detection part 2 on one side of infrared ray transmission board 1, while an infrared ray transmission filter 3 is formed on the opposite face of the board 1. Below the detection part 2 of the board 1 a heat separation space 5 for restraining heat conduction between the detection part 2 and the board 1 is formed. A lens 8 is formed on the inner wall face 5A of the space 5 being in a face-to-face relation with the detection part 2.

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 detecting section and the infrared transmitting 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 detection chip 21 having an infrared detection portion such as a thermistor is attached to the stem 20, and above the chip 21,
The infrared transmission filter 3e, which passes only infrared rays and blocks unnecessary wavelength components that become noise, is attached to the cap 22.
It is held and placed in. On the other hand, in the past, for example, when detecting a human body by infrared detection,
In order to increase the infrared detection sensitivity, a lens such as a condenser lens is incorporated in the infrared detection device and used together.

[0003]

However, in the means of using another lens together in detecting infrared rays, the process of assembling the lens in the infrared detecting apparatus becomes complicated and the manufacturing cost becomes high, and the whole infrared detecting apparatus is large in size. There is a drawback that In addition, in the conventional device shown in FIG. 7, it is necessary to cut out the infrared transmitting filter 3e into a fine shape that matches the shape of the opening 23 of the cap 22 and attach this to the opening 23 of the cap 22 with an adhesive. However, there are drawbacks that the number of assembling steps is large and the manufacturing cost is further increased. Further, in the above-mentioned conventional one, the infrared transmission filter 3e is limited due to restrictions such as assembling workability of each component.
Since it is necessary to separate the infrared detection chip 21 and the infrared detection chip 21 to some extent, there is also a drawback that the overall structure of these is bulky. Incidentally, if the infrared transmission filter 3e is directly superposed on the surface of the infrared detection chip 21, the mounting structure of both can be simplified and made compact. However, with such means, other than heat absorption from the infrared detection chip 21 to the stem 20 side, , Infrared detection chip 21 to infrared transmission filter 3e
Since the heat absorption to the infrared rays is also added, the temperature change of the infrared ray detection chip 21 due to the infrared ray absorption becomes slow, and the sensitivity of the infrared ray detection decreases. Further, the responsiveness is further deteriorated due to an increase in the apparent heat capacity of the entire infrared detection site, and there is a drawback that it is inferior in practicality. Therefore, the present invention can be manufactured easily and compactly and has excellent responsiveness for infrared detection, and can eliminate the inconvenience of using a desired lens externally. The purpose is to provide an element.

[0004]

The infrared detecting element according to the present invention, which has been proposed to achieve the above object, has an infrared detecting portion provided on one surface of the infrared transmitting substrate and the infrared transmitting substrate An infrared ray transmitting filter is formed on the opposite surface, and an infrared ray separating space is formed below the infrared ray detecting portion of the infrared ray transmitting substrate to suppress heat conduction between the infrared ray detecting portion and the infrared ray transmitting substrate. In the detection element, a lens is formed on the inner wall surface of the heat separation space section facing the infrared detection section.

[0005]

In the infrared detecting element having the above-mentioned structure, the infrared rays passing through the infrared transmitting filter and the infrared transmitting substrate from the side opposite to the infrared transmitting substrate pass through the lens on the inner wall surface of the heat separation space and are condensed. Alternatively, the infrared light is absorbed by the infrared detecting portion in a dispersed state, and infrared rays are detected. Therefore,
It is not necessary to use a condensing or dispersing lens separately from the infrared detecting element. If the lens is formed as a converging convex lens, the viewing angle can be narrowed to obtain a magnified image, and infrared detection with high sensitivity can be performed. Also,
If it is a concave lens, the viewing angle is enlarged and a reduced image is obtained. Further, since the lens is formed on the inner wall surface of the heat separation space, the opposite surface side of the infrared transmission substrate provided with the infrared transmission filter is formed into a flat surface state which is optimum for forming the infrared transmission filter. Can be kept. Furthermore, since the infrared detecting section is thermally separated from the substrate by the heat separating space section and is also separated from the infrared transmitting filter, improper heat conduction from the infrared detecting section to each of these sections is suppressed, and the infrared detecting section The apparent heat capacity at the entire location is also reduced. Therefore, the temperature change of the infrared detecting section due to the infrared absorption becomes sensitive, and the infrared detecting sensitivity and responsiveness of the infrared detecting section are improved. In the infrared detecting element, since the infrared transmitting filter and the lens are formed on the infrared transmitting substrate having the infrared detecting portion, the whole is not bulky, and the whole can be formed in a one-chip small size. Moreover, since the infrared detector and the infrared transmission filter can be brought close to each other, the viewing angle can be expanded.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an infrared detecting element A according to the present invention, and FIG. 2 is a plan view thereof. The infrared detection element A
Is provided with an infrared detecting portion 2 on the front surface side of the infrared transmitting substrate 1 and an infrared transmitting filter 3 on the rear surface side thereof, and a heat separation space portion 5 inside the infrared transmitting substrate 1 below the infrared detecting portion 2.
Is provided, and the lens 8 is formed on the inner wall surface thereof.
Here, the infrared transparent substrate 1 is composed of two upper and lower substrates 1a and 1a.
b is integrally bonded to form a single substrate, and as a material thereof, an appropriate one can be selected from general semiconductor substrate materials as long as it can transmit infrared rays well. It can be used. Specifically, a silicon substrate is preferable, and a silicon substrate having a specific resistance of 0.1 Ωcm or more is particularly preferable because it has excellent infrared transmittance. An insulating film 4 is provided on the surface of the infrared transmitting substrate 1, but the insulating film 4 also has a function as an infrared absorbing film.
It is made of a material that is suitable for a semiconductor process and has a high infrared absorption rate. As a specific example, a silicon oxide film or a multilayer film of silicon oxide and silicon nitride is applied.

The heat separation space 5 is formed by removing a part of the infrared transmitting substrate 1 below the insulating film 4. This is formed by forming a desired notch concave portion on the back surface side of the upper substrate 1a by etching or the like before adhering the upper and lower substrates 1a and 1b as described later. The lens 8 is formed, for example, as a Fresnel lens for condensing by processing the inner wall surface 5A of the inner wall surface of the heat separation space portion 5 located at a position facing the infrared detection portion 2. As a Fresnel lens forming means, before bonding the upper and lower substrates 1a and 1b, an electron beam resist is coated on the lower substrate 1b, a desired lens pattern is formed by electron beam lithography, and ion beam etching is performed. The shape of the electron beam resist may be transferred to the surface of the substrate 1b.

The infrared detecting section 2 is constructed by sequentially stacking a thin film resistor 2b and electrodes 2a, 2a on an insulating film 4 corresponding to a position above the heat separation space 5, and the infrared transmitting substrate 1 And are thermally separated via the heat separation space 5. Among them, 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 electrodes 2a, 2a are formed in a comb-shaped planar shape facing each other so that a change in the resistance value of the thin film resistor 2b can be accurately detected, and are configured to contact the thin film resistor 2b in a large area. Further, each end thereof is connected to a signal processing circuit 6 described later. The materials of the electrodes 2a, 2a are also preferably formed of a thin film material suitable for a semiconductor process. Examples of the material include normal electrode materials such as Au and Al, and T
i, Zr, V, Nb, Ta, Cr, Mo, W, Ni, P
When a metal alloy of t, Pd, or the like or a silicide with polycrystalline silicon is used, the infrared absorption rate is high, and thus the detection sensitivity can be improved.

The infrared transmitting filter 3 on the back surface side of the infrared transmitting substrate 1 blocks electromagnetic waves other than infrared rays and allows infrared rays to pass therethrough. For example, magnesium oxide having a high refractive index and fluorine having a low refractive index are used. A multilayer film of magnesium is applied. A signal processing circuit 6 including an amplification circuit and other circuits similar to those of a normal infrared detection device is provided in another portion of the infrared transmission substrate 1 below the insulating film 4.
The ends of the electrodes 2a, 2a are connected to the appropriate places in a state of passing through the insulating film 4.

In manufacturing the infrared detecting element A having the above structure, the upper and lower substrates 1a and 1b of the infrared transmitting substrate 1 are individually manufactured and then adhered to each other. As shown in FIG.
After the signal processing circuit 6 is formed on a by a method according to a normal semiconductor process, the insulating film 4 is formed on the surface of the substrate 1a. Next, as shown in FIG. 3B, the lower surface side of the substrate 1a at the position where the infrared detecting section 2 is to be provided is removed by anisotropic etching or the like to form the heat separation space section 5. After that, as shown in FIG.
On the insulating film 4 above the thin film resistor 2b and the electrodes 2a, 2
A is deposited by vapor deposition, sputtering, or the like. on the other hand,
As shown in FIG. 3D, on the substrate 1b side, the infrared transmission filter 3 is formed on the lower surface side by vapor deposition or the like, and at the position corresponding to the heat separation space portion 5 on the upper surface side as described above. The lens 8 is formed by etching means or the like. Therefore, if the two substrates 1a and 1b are thereafter adhered by an appropriate means known in the related art, the infrared detecting element A shown in FIG. 1 can be obtained.

The infrared detecting element A having the above structure is a semiconductor chip in which an infrared detecting portion 2 and an infrared transmitting filter 3 are provided on both sides of an infrared transmitting substrate 1, and a lens 8 is integrally formed inside a heat separation space. It is configured as, and its size can be made extremely small. Next, when the infrared rays are transmitted from the lower side of the back surface of the infrared transmission substrate 1 through the infrared transmission filter 3 and enter the infrared transmission substrate 1 in use, the infrared rays are collected by the condenser lens 8. It is absorbed by silicon oxide or silicon nitride in the insulating film 4 functioning as an infrared absorbing film, and the temperature of the thin film resistor 2b of the infrared detecting unit 2 provided on the insulating film 4 changes. A change in the resistance value of the thin film resistor 2b due to such a temperature change can be detected through the signal processing circuit 6 to which the electrodes 2a and 2a are connected. Infrared transmission filter 3 provided on the front and back of infrared transmission substrate 1
Since the infrared detector 2 and the infrared detector 2 are close to each other, the viewing angle is wide.

Since the infrared light received by the infrared detecting section 2 is condensed by the lens 8, even if the infrared detecting element A receives a small amount of infrared light, it is condensed and detected. It is possible to increase the sensitivity. That is, by providing the condenser lens 8, the same action as that of the infrared image is magnified equivalently by narrowing the viewing angle received by the infrared detecting section 2 can be obtained. Further, since the infrared detecting section 2 and the infrared transmitting substrate 1 are in a state of being thermally separated by the heat separating space section 5, it is possible to prevent heat from escaping from the infrared detecting section 2 to the infrared transmitting substrate 1 side. Furthermore, since the infrared transmission filter 3 is provided on the back surface side of the infrared transmission substrate 1, the heat of the infrared detection unit 2 is not absorbed by the infrared transmission filter 3. Therefore, the temperature change of the infrared detector 2 due to the infrared absorption becomes sensitive, and the response speed of infrared detection can be increased. Further, since the infrared detecting section 2 is provided separately from the infrared transmitting substrate 1, the apparent heat capacity of the entire infrared detecting section 2 can be reduced, and the infrared detecting sensitivity can be further improved. Since the signal processing circuit 6 is provided on the infrared transparent 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 a series of the infrared detecting section 2 and the like. In the manufacturing process of, 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 shows a case where the inner wall surface 5A of the heat separation space 5 is formed into a convex curved surface to form a convex lens 8a.
FIG. 5 shows a case where the inner wall surface 5A is formed into a concave curved surface to form the concave lens 8b. In the present invention as set forth in claim 1, the lens 8 is not limited to the Fresnel lens, and may be configured as a lens having a form as shown in FIGS. 4 and 5. In the present invention, when the concave lens is formed, the infrared rays to be received can be dispersed, so that the viewing angle received by the infrared detecting section 2 can be expanded and the infrared image can be reduced. The infrared detection element A shown in FIG. 6 has a structure in which the thin film resistor 2b is sandwiched between the upper and lower electrodes 2a and 2a, and the electrode structure may be used in the present invention.

[0011]

As described above, according to the infrared detecting element of the present invention, the whole can be manufactured in a very small one-chip shape by a simple manufacturing means, and a wide viewing angle for infrared detection can be secured. In addition to the effect that can be obtained, there is no need to separately use an external lens as in the conventional case when the human body is used, and the convenience that the lens can be directly used for human body detection can be obtained. In addition, it is possible to suppress unreasonable heat conduction from the infrared detecting section to the infrared transmitting substrate or the infrared transmitting filter side, and improve the response performance of infrared detection. In addition, since the lens is formed on the inner wall surface of the heat separation space, it is possible to suppress the increase in size of the infrared detection element, and it is possible to form the back surface of the infrared transmission substrate forming the infrared transmission filter as a flat surface. Therefore, there is also an advantage that no trouble occurs in forming the infrared transmission filter.

[Brief description of drawings]

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

FIG. 2 is a plan view showing an embodiment of an 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 sectional view of an essential part showing another embodiment of the lens formed in the infrared detection element.

FIG. 5 is a cross-sectional view of essential parts showing another embodiment of the lens formed in the infrared detection element.

FIG. 6 is a cross-sectional view of essential parts showing another embodiment of the electrodes formed on the infrared detection element.

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

[Explanation of symbols]

 1 Infrared Transmission Substrate 2 Infrared Detection Section 2a Electrode 2b Thin Film Resistor 3 Infrared Transmission Filter 4 Insulation Film 5 Thermal Separation Space Section 5A Inner Wall Surface 6 Signal Processing Section 8 Lens A Infrared Detection Element

Claims (2)

[Claims] 1. An infrared detecting portion is provided on one surface of the infrared transmitting substrate, and an infrared transmitting filter is formed on the opposite surface of the infrared transmitting substrate. Below the infrared detecting portion of the infrared transmitting substrate, An infrared detection element in which a heat separation space part for suppressing heat conduction between the infrared detection part and the infrared transmission substrate is formed, wherein a lens is provided on an inner wall surface of the heat separation space part facing the infrared detection part. An infrared detection element characterized by being formed. 2. The infrared detection element according to claim 1, wherein the lens is a Fresnel lens formed by etching a surface of an inner wall surface of the heat separation space to form a plurality of corrugated portions in a concentric shape.