JPS6142869B2 - - Google Patents

Abstract

PURPOSE:To prevent deterioration of characteristics of an infrared ray camera device due to strain by forming an infrared ray detector and its input unit corresponding thereto asymmetrical in vertical direction and connecting therebetween with conductive material having bent buffer. CONSTITUTION:A CCD and its input unit 15, and a protective layer 18 are formed on a substrate 14, and a resist pattern 19 is formed on predetermined portion thereof. Then, an Au layer 17a is selectively evaporated, and a thick Au layer 17b is superimposed thereon. Subsequently, when the resist 19 is molten and removed, a connecting member 17 is completed in the input unit 15 at the CCD. The connecting member 17 is connected to a semiconductor substrate 10 having the detector 12 in predetermined positional relationship. According to this configuration, the mechanical strain at connecting time does not deteriorate the detector, nor disconnect the connector at the step of thermal hysteresis.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a connecting portion in an infrared imaging device that combines a large number of infrared sensing elements formed on a substrate and a charge transfer element for signal processing formed on a substrate other than the substrate. Regarding improvements.

An infrared detection element receives infrared rays emitted from the object's surface due to the object's unique temperature, and the electrical signal generated by its photoelectric conversion function is sent to a charge transfer device (hereinafter abbreviated as CCD) for signal processing.
An infrared imaging device configured to output data in time series to the outside is well known. There are several possible ways to configure such an infrared imaging device. First, there is a method of forming a CCD using a multi-component semiconductor with a narrow energy gap and sensitivity to infrared light, such as mercury-cadmium-tellurium (HgCdTe), which is the same material used for infrared detectors. Another method is being considered in which indium-antimony (InSb) is formed by vapor deposition on the silicon chip that constitutes the infrared light detection section. However, the former method has large variations between devices, and the latter method has problems such as image bleeding, difficulty in manufacturing, and difficulty in obtaining a deposited layer with a uniform composition, so neither of these methods is practical. Therefore, a common method is to form an infrared sensing element on a multi-component semiconductor substrate, separately form a CCD on a Si substrate, and then combine them using a method with already established manufacturing technology.
Naturally, in order to improve the resolution of an infrared imaging device with such a configuration, a large number of infrared sensing elements are required, and it is difficult to connect these sensing elements to a CCD using the wire bonding method. Therefore, a method has been adopted in which a metal protrusion is provided on each of the detection element and the CCD input section, and the detection element and the CCD input section are connected via the metal protrusion by making them face each other. FIG. 1 is an enlarged cross-sectional view of a main part showing the structure of a connection part between an infrared detection element and a CCD input section of a conventional infrared imaging device, in which 1 is, for example, a p-type multi-component semiconductor substrate (for example, HgCdTe); This p
An infrared sensing element 3 is constructed by forming an n-type diffusion layer 2 on a type substrate 1, and each infrared sensing element 3 is further formed with a protruding electrode 4a made of, for example, indium (In). On the other hand, for example, a predetermined CCD (not shown) is formed on a p-type Si substrate 5, and its input section 6 is composed of an n-type diffusion layer 7. A protruding electrode 4b made of In is formed. Then, the protruding electrodes 4a and 4b of the sensing element 3 and the CCD input section 6 are aligned, the substrates 1 and 5 are fixed so as to be pressed together, and the protruding electrodes 4a and 4b are joined by heating and welding at about 60°C, for example. Seshime, detection element 3
and a CCD input section 6 are connected via a connecting member 4. Note that 8 is a protective film (for example, SiO ₂ ) for the pn junction forming the sensing element 3 and the CCD input section 6. In such a configuration, infrared rays incident from the upper surface side of the substrate 1 are photoelectrically converted by the infrared detecting element 3 and passed through the connecting member 4.
The signal is input to the CCD input section 6.

In such a connection structure, the protruding electrode 4
When a and 4b are pressed together and heat welded, the detection element 3
Mechanical stress is applied to the CCD input section 6, and the pn junction of the sensing element 3 may be particularly damaged, resulting in deterioration of the element characteristics. In addition, this infrared imaging device is used after being cooled down to liquid nitrogen temperature (for example, 77°C), and when it is not in use it is at room temperature, so it undergoes a thermal history between when it is in use and when it is not in use.
During this thermal history process, the multi-component semiconductor substrate 1 and the Si substrate 5
Since the coefficients of thermal expansion are different from each other, the rates of contraction and expansion are different, and as a result, the connecting member 4 may be disconnected, leading to a decrease in the manufacturing yield and reliability of the device.

The present invention was made in view of the above points, and its purpose is to provide a large number of infrared detection elements and a corresponding one.
It is possible to prevent characteristic deterioration of the sensing element caused by mechanical stress when connecting it to the CCD input section, and also to prevent disconnection of the connecting member caused by thermal history during operation and non-operation. An object of the present invention is to provide an infrared imaging device having a structural connection part, and its feature is that a large number of infrared detection elements formed on a substrate and a charge transfer device for transferring signal charges from the detection elements are arranged facing each other. In the infrared imaging device in which the corresponding input parts of each of the sensing element charge transfer devices are connected via a conductive member, the sensing element and the corresponding input part are arranged in a vertically non-directly facing position. In addition to placing it in
They are connected by a conductive member having a horizontally bent buffer section.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is an enlarged cross-sectional view of the main parts for explaining the schematic structure of the connection part between the infrared detection element and the CCD input part of the infrared imaging device according to the present invention,
10 is, for example, a p-type multi-component semiconductor substrate (for example,
HgCdTe), an n-type diffusion layer 11 is formed on this p-type substrate 10 to constitute an infrared sensing element 12, and a protruding electrode 13 made of, for example, In is formed on each infrared sensing element 12. There is.
On the other hand, a predetermined CCD is mounted on the p-type Si substrate 14.
(not shown) is formed, and its input section 15 is n
It is composed of a type diffusion layer 16. Each input section 15 of the CD is provided with a connecting member 17 that has one end connected to the input section 15, protrudes vertically, is bent horizontally in the middle, and is suspended at the other end to have a buffering function. These connecting members 1
7 is made of a conductor such as gold (Au). And each detection element 12 and CCD input section 15
The substrates 10 and 14 are fixed so that they are placed in a non-direction relationship in the vertical direction, and the protruding electrode 13 and the horizontal portion of the connecting member 17 are opposed to each other and are pressed against each other. The protruding electrode 13 and the connecting member 17 are bonded by heat welding.
It is connected to the horizontal part of. The infrared rays incident from the upper surface side of the substrate 10 are transmitted to the infrared detecting element 12.
is photoelectrically converted, and the protruding electrode 13 and the connecting member 1
7 and is input to the CCD input section 15. Note that the pn junction of the sensing element 12 and the CCD input section 15 is covered with a protective layer 18 of, for example, SiO ₂ . In this way, the protruding electrode 13 provided on the sensing element 12 and the vertically protruding portion of the connecting member 17 provided on the CCD input section 15 connect to the connecting member 17.
At this time, the horizontally bent portion of the connecting member 17 acts as a buffer band to reduce the mechanical stress applied to the sensing element 12 and the CCD input section 15. is alleviated, making it possible to prevent property deterioration due to mechanical stress that has occurred particularly in the sensing element 12. Furthermore, when using this infrared imaging device,
During the thermal history process when not in use, the mechanical stress caused by the difference in thermal expansion coefficients between the multi-component semiconductor substrate 10 and the Si substrate 14 is also alleviated by the buffering function of the connecting member 17, and the result is detected. It is also possible to prevent disconnection of the connection between the element 12 and the CCD input section 15 due to thermal history.

Next, an example of a method for forming the connecting member 17 as described above will be described with reference to FIGS. 3A to 3E. First, a predetermined CCD as shown in Figure 3A (not shown)
A substrate 14 on which the input section 15 and the protective layer 18 are formed in advance is prepared, and a photoresist pattern 19 is formed on the part of the connecting member that is to be bent in the horizontal direction and suspended in the air, as shown in FIG. . Next, using a metal mask, an Au layer 17a as shown in FIG.
A thick Au layer 17b (for example, layer thickness of 30 μm or more) is formed on the layer 17a by electroless plating or electroforming. After that, by dissolving and removing the photoresist 19, the image shown in FIG. 3E is obtained.
A connecting member 17 consisting of Au layers 17a and 17b is
It can be formed in the CCD input section 15. Note that it is of course possible to construct the connecting member 17 with a conductor other than Au, such as copper (Cu), but in this case, since the protruding electrode on the sensing element side is made of In, the surface of the connecting member is plated with Au. It is desirable to improve the adhesion with In. Furthermore, it is of course possible to provide the connecting member 17 on the infrared sensing element.

As is clear from the above description, the present invention can prevent characteristic deterioration that occurs particularly in the sensing element due to mechanical stress when connecting the infrared sensing element and the CCD input section, and furthermore, during the operation of the infrared imaging device. It is also possible to prevent disconnection of the connection between the sensing element and the CCD input section, which occurs during the thermal history process during non-operation, and is extremely effective in improving the manufacturing yield and reliability of the device.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view of the main parts for explaining the structure of the connection between the infrared sensing element and the CCD input section of a conventional infrared imaging device, and FIG. 2 shows the infrared sensing element of the infrared imaging device according to the present invention. An enlarged sectional view of the main part to explain the structure of the connection part with the CCD input part,
FIGS. 3A to 3E are process diagrams for explaining a method of forming a connecting portion according to the present invention. 1, 10: Multidimensional semiconductor substrate, 3, 12: Infrared sensing element, 4a, 4b, 13: Projection electrode, 5, 1
4: Si substrate, 6, 15: CCD input section, 8, 1
8: Protective film (SiO ₂ ), 17: Connection member, 17
a, 17b: Au layer, 19: resist layer.

Claims (1)

[Claims] 1 A large number of infrared sensing elements formed on a substrate and a charge transfer device that transfers signal charges from the sensing elements are arranged facing each other, and a conductive member is connected between each of the detection elements and each corresponding input part of the charge transfer device. In the infrared imaging device, the sensing element and the input section corresponding to the sensing element are placed in a non-direction relationship in the vertical direction, and a conductive member having a buffer section bent in the horizontal direction is provided between them. An infrared imaging device characterized by being connected.