JPH06132550A - Infrared detector - Google Patents

Abstract

PURPOSE:To obtain an infrared detector in which an output signal with reduced noise can be obtained. CONSTITUTION:An electrode section 3 on the light-receiving layer 2 side of an infrared-detecting element 20 is soldered to an electrode pattern 6 provided on an insulating submount 5 so that a signal light 11 of 10mum band is received from the rear face side of the substrate 1 of the infrared-detecting element 20, and a mask patten 21 composed of insulating film or metal film not transmitting the light of 10mum band and having a circular opening 21a having the same diameter as that of the spot of the signal light 11 for making the signal light 11 pass through is formed in the rear face of the substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of an infrared detector.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing a configuration of a signal detecting portion of a conventional photoconductive infrared detector, FIG. 4 (a) is a perspective view thereof, and FIG. It is sectional drawing which shows the structure of the infrared detection element shown in a).

In FIG. 4 (b), reference numeral 10 denotes an infrared detecting element. The infrared detecting element 10 comprises a CdTe substrate 1, a light receiving layer 2 made of CdHgTe formed on the CdTe substrate 1, and a light receiving layer 2. The light receiving layer 3 which is composed of the electrode portions 3 formed on the upper surface and whose surface is exposed between the electrode portions 3 is the light receiving portion 4. Then, the infrared detection element 10
However, as shown in FIG. 4 (a), the conductive submount 15
The electrode portion 3 of the infrared detection element 10 which is soldered on
And a conductive lead 8 disposed on the conductive submount 15 via an insulating film 7 are wire-bonded by a wire 9 to form a signal detecting portion of a photoconductive infrared detecting device. There is.

An infrared detecting device of this type usually has a signal detecting section composed of the constituent elements including the conductive submount 15 shown in FIG. 4 and the infrared detecting element 10 disposed on the upper surface thereof. However, it is used with the modular optical system for guiding the signal light (not shown) to the light receiving unit 4 covered with a metal casing (not shown), and the signal detecting unit and the optical system are shielded from the outside. To be done.

Next, the operation will be described. The light receiving layer 2 of the infrared detecting element 10 is Cd having a narrow band gap.
It is made of compound semiconductor such as HgTe, and has an energy larger than this band gap, that is, 1
When the signal light in the 0 μm band is guided to the light receiving section 4 by an optical system (not shown) and is incident on the light receiving section 4, excess carriers are generated in the light receiving layer 2, and the excess carriers cause a change in the electrical conductivity of the element. , The electrodes on both sides of the element 3, the wires 9,
And, it is taken out to the outside as an electric signal through the lead portion 8.

[0006]

The above-mentioned conventional infrared detector has the following problems. FIG. 5 shows infrared rays guided to the light receiving portion 4 of the infrared detecting element 10, that is, 1
This shows how the signal light 11 in the 0 μm band is received by the light receiving section 4, and as shown in the figure, until the signal light 11 reaches the light receiving section 4 through the optical system in the housing (not shown). In addition, a part of the signal light is reflected by the inner wall surface of the housing, and the reflected light becomes stray light 12 and reaches the light receiving unit 4, and as a result, the light receiving unit 4 also senses the stray light 12 and the output signal There was a problem that noise was generated. Further, in an infrared detection device using an infrared detection element, which is usually provided with a light reception layer for detecting light in the 10 μm band such as CdHgTe as this type of light reception layer, the casing is cooled from the outside and the inside of the device is cooled. However, when the temperature inside the device rises due to the heat generated by the element during operation, heat rays are radiated from the inner wall of the housing and the above-mentioned optical system housed in a module, and the light receiving unit 4 uses this as stray light. As with No. 22, there is a problem in that noise is generated in the output signal by sensing.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an infrared detector capable of obtaining an output signal with reduced noise.

[0008]

In an infrared detecting device according to the present invention, an electrode portion on the light receiving layer side of an infrared detecting element is joined to an electrode pattern formed on an insulating submount to detect infrared rays from the back surface side of a substrate. A film-like mask member is provided on the back surface of the substrate so that the signal light is incident on the inside of the device.

Further, the infrared detecting device according to the present invention is
A mask member made of an insulating plate or a metal plate that allows only signal light to pass toward the light receiving layer of the infrared detection element is arranged above the infrared detection element in which the back surface of the substrate is soldered to the submount.

[0010]

In the present invention, the mask member for blocking the incident path of stray light or heat rays generated in the device to the light receiving layer is provided above the light receiving layer of the infrared detecting element. Can be reduced, and a noiseless output signal can be obtained.

[0011]

EXAMPLES Example 1. FIG. 1 is a diagram showing a structure of an infrared detecting element which constitutes a signal detecting portion of an infrared detecting device and an assembling process of the signal detecting portion according to the first embodiment of the present invention. FIG. FIG. 1 (b) is a perspective view showing the structure of the element, and FIG. 1 (b) is a sectional view showing a step of mounting the infrared detecting element on an insulating submount. In the figure, the same reference numerals as those in FIG. 4 denote the same or corresponding portions, 5 is a submount made of an insulating material such as boron nitride or silicon carbide, and 6 is an upper surface of the insulating submount 5 so as not to come into contact with each other. The formed electrode pattern, 20 is an infrared detection element, 21 is a metal film made of, for example, Al or Cu in which an opening 21a through which signal light passes is formed, or Si, for example.
10 μm composed of an insulating film made of O2 or Si3 N4
It is a mask pattern that does not transmit the band light.

The assembly process of the infrared detector will be described below. A mask pattern 21 made of a metal film or an insulating film having a circular opening 21a having the same diameter as the spot diameter of the signal light 11 is formed on the back surface of the CdTe substrate 1 of the infrared detecting element 20 by the CVD method, the vapor deposition method or the sputter vapor deposition method. It is formed by using. Next, for example, Cr-A is mounted on the insulating submount 5.
After forming the electrode pattern 6 by metallization such as u,
The electrode part 3 on the light receiving layer 2 side of the infrared detection element 20 is soldered and bonded to the electrode pattern 6 on the submount 5 so as not to short-circuit them. Next, conductive leads (not shown) are formed on the insulating submount 5 similarly to the conventional infrared detecting device shown in FIG.
The signal detector is assembled by wire bonding the conductive lead and the electrode pattern 6. Then, after that, each component constituting the signal detecting section including the insulating submount 5 and the infrared detecting element 20 provided on the insulating submount 5 is changed to the infrared detecting element 20 for detecting the signal light. The infrared detection device is assembled by covering it with a not-illustrated modularized optical system for guiding to the above and a metal casing not shown.

FIG. 2 is a view showing a state in which the signal light is received by the infrared detecting element 20 of the signal detecting section in the infrared detecting device thus assembled. As shown in FIG. 2, the CdTe substrate 1 is shown. Through the opening 21a on the back side of Cd
The signal light 11 is incident on the Te substrate 1, and the signal light 11 reaches the light receiving layer 2 through the inside of the CdTe substrate 1.

In the infrared detector of this embodiment, as shown in FIG. 2, the signal light 11 emits the infrared detector element 2.
The stray light 12 that is incident from the back surface side of the CdTe substrate 1 of 0 through the circular opening 21a having the same opening diameter as the spot diameter of the signal light 11 and is generated by reflecting the signal light 11 on the inner wall of the housing is Mask pattern 2 made of metal film or insulating film
Since the light is blocked by 1, the light receiving layer 3 hardly senses the stray light 12, and noise can be reduced. Further, since the light receiving unit 4 is laid down on the upper surface of the insulative submount 5, the light receiving unit 4 hardly detects heat rays radiated from the inner wall of the housing or the optical system, and noise is reduced. can do.

Although the light receiving portion 4 is exposed from the opening 21a in the above embodiment, ZnS which transmits light in the 10 μm band through the opening 21a but does not transmit heat rays due to radiation.
A film may be provided, and in this case, although a small amount, the heat ray reaching the light receiving portion 4 through the opening 21a can be completely blocked, and the noise generated in the output signal can be further reduced. You can

Example 2. FIG. 3 is a diagram showing a configuration of a signal detection unit of an infrared detection device according to a second embodiment of the present invention and a state in which signal light is incident on the signal detection unit, and FIG. A top view and FIG. 3B are cross-sectional views thereof. In the figure, the same reference numerals as those in FIG. 4 indicate the same or corresponding portions, and 13 is a metal plate made of, for example, Al or Cu or a metal plate made of, for example, SiO2 or It is a plate-shaped member that is made of an insulating plate made of Si3 N4 and does not transmit light in the 10 μm band. Then, in this infrared detection device, the opening 13a
Is placed above the light receiving surface 4 of the infrared detecting element 10, the end of the plate member 13 has a conductive submount 1
It is bonded to the upper surface of the conductive lead 8 on the upper surface 5.

Also in this infrared detecting device, similarly to the infrared detecting devices of the prior art and the first embodiment, a signal detecting section including an infrared detecting element provided on the submount and the cebu mount is constructed. The various components that
It is covered by a metal casing (not shown) together with a modularized optical system for guiding the signal light to the signal detection unit.

In the infrared detecting device of this embodiment, a circular opening 13a having the same diameter as the spot diameter of the signal light 11 received by the light receiving portion 4 is provided above the light receiving portion 4 of the infrared detecting element 10. Since the plate-like member 13 in which the signal is formed is arranged and the signal light 11 passes through the circular opening 13a and is incident on the light-receiving unit 4, the signal light 11 is transmitted in the device, that is, in the housing. Stray light 1 generated by reflection of light 11
2 is blocked by the plate-shaped member 13 and does not reach the light receiving portion 4. Further, the plate-shaped member 13 made of a metal plate or an insulating plate radiates from the inner wall of the housing or a modularized optical system. Since the generated heat rays are cut off, the amount of heat rays sensed by the light receiving unit 4 is reduced, and noise generated in the output signal can be reduced.

In the above embodiment, the plate member 13 is adhered to the upper surface of the conductive lead. However, a member for supporting the plate member 13 is separately formed on the submount, and the plate member 13 is attached thereto. May be adhered.

Further, in the above embodiment, the plate-like member 13 made of a metal plate or an insulating plate having the opening 13a through which the signal light 11 can pass is arranged above the light receiving portion 4, but the plate-like member 13 is also provided. A metal plate made of a metal such as ZnS that transmits light in the 10 μm band is laid on the upper surface or the lower surface of the opening of the opening 13
It is also possible to block a, and in this case, although a small amount, the heat ray reaching the light receiving portion 4 through the opening 13a can be completely blocked, and the noise generated in the output signal can be further reduced.

[0021]

As described above, according to the present invention, the electrode portion on the light receiving layer side of the infrared detecting element is joined to the electrode pattern formed on the insulative submount, and the infrared detecting element is exposed from the back surface side of the substrate. Since the signal light is made incident on the substrate and a film-shaped mask member that allows only the signal light to pass through is provided on the back surface of the substrate, the light receiving layer is less likely to detect unnecessary stray light or heat rays other than the signal light. Therefore, there is an effect that the noise of the output signal can be reduced.

Further, according to the present invention, an insulating plate or a metal plate for passing only the signal light toward the light receiving layer of the infrared detection element is provided above the infrared detection element whose back surface is soldered to the submount. Since the mask member made of is disposed, the light-receiving layer is less likely to detect unnecessary stray light or heat rays other than the signal light, and the noise of the output signal can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a signal detection unit of an infrared detection device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing how signal light is received by an infrared detection element of a signal detection unit of the infrared detection device according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a signal detector of an infrared detector according to a second embodiment of the present invention and how signal light is incident on the signal detector.

FIG. 4 is a diagram showing a signal detection unit of a conventional infrared detection device.

5 is a diagram showing how the infrared light detecting element of the signal detecting unit shown in FIG. 4 receives signal light.

[Explanation of symbols]

 1 CdTe substrate 2 Light receiving layer made of CdHgTe 3 Electrode part 4 Light receiving part 5 Insulating submount 6 Electrode pattern 7 Insulating film 8 Conductive lead 9 Wire 10 Infrared detecting element 11 10 μm band signal light 12 Stray light 13 10 μm band Plate-shaped member 13a that does not transmit light 15a Opening 15 Conductive submount 20 Infrared detection element 21 Mask pattern that does not transmit light in the 10 μm band 21a Opening

Claims (6)

[Claims] 1. An insulating submount provided with two independent metal patterns on its upper surface, and an electrode portion on the light-receiving layer side of the two electrode patterns are soldered to the insulating submount.
An infrared detecting element for detecting a signal light of 0 μm band, and a conductive lead which is arranged around the infrared detecting element on the insulating submount and outputs an electric signal converted by the infrared detecting element to the outside. A signal detection unit comprising
A photoconductive infrared detecting device housed in a metal casing together with an optical system for guiding the signal light of the 10 μm band to the signal detecting section, wherein only the signal light is provided on the back surface of the substrate of the infrared detecting element. An infrared detector comprising a mask member made of an insulating film or a metal film which is incident on the light receiving layer. 2. The infrared detecting device according to claim 1, wherein the mask member made of the insulating film or the metal film is the
A circular aperture having the same diameter as the spot diameter of the signal light of 0 μm band is formed, and the insulating film pattern or metal film pattern does not transmit the signal light of 10 μm band. Infrared detector featuring. 3. The infrared detecting device according to claim 2, wherein the circular opening is provided with a ZnS film that transmits the signal light in the 10 μm band. 4. A conductive submount, an infrared detection element for detecting signal light in the 10 μm band, the back surface of which is adhered to the conductive submount, and the infrared detection on the conductive submount. A signal detecting section arranged around the element and provided with a conductive lead for outputting the electric signal converted by the infrared detecting element to the outside, for guiding the signal light in the 10 μm band to the signal detecting section. In a photoconductive infrared detector housed in a metal housing together with an optical system, a mask made of an insulating plate or a metal plate that passes only the signal light toward the light receiving layer above the infrared detecting element. An infrared detector characterized in that members are arranged. 5. The infrared detection device according to claim 4, wherein the mask member made of the insulating plate or the metal plate has a circular opening having the same diameter as a spot diameter of the signal light for passing the signal light. An infrared detection device having a portion and made of an insulating plate or a metal plate that does not transmit the signal light in the 10 μm band. 6. The infrared detection device according to claim 5, wherein a plate-shaped member made of ZnS is arranged above the mask member or between the mask member and the infrared detection element. Infrared detector.