JPS6037413B2 - infrared detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an infrared detection device that has a high infrared detection sensitivity and a structure that is easy to manufacture.

In a pyroelectric type infrared detection device that uses the pyroelectric effect, the pyroelectric crystal is thinned to about 30 to 50 m thick to reduce heat capacity and quickly respond to changes in infrared heat energy for detection. Efforts are being made to improve sensitivity.

In addition, in order to prevent an increase in heat capacity, the pyroelectric crystal is suspended in the air, or a thermal insulator is provided on the substrate.
That is, as shown in FIG.
A pyroelectric crystal 3 having a pyroelectric crystal 3 formed on both surfaces was attached to the electrodes 1 and 2, respectively, and supported by a wire 4, and was suspended on a mount 5. Alternatively, as shown in FIG. 2, the ground electrode 2 was adhesively fixed to the surface of a heat insulating substrate 6 provided on a mount 5. However, in the suspended structure, the pyroelectric crystal 3 is extremely thin, making it extremely difficult to handle and manufacture, and has the disadvantage of poor durability and reliability. Further, the structure shown in FIG. 2 has a problem in that it is difficult to attach the lead wire 4 to the ground electrode 2. Therefore, as shown in FIG. 3, a film 7 of Sn02 or the like is conventionally formed on a thermally insulating substrate 6.
A contrivance has been made to take out the IJ-wire 4 from the Sn02 film 7 which is electrically conductive to the ground electrode 2. However, even if the above measures are taken, it is still necessary to mount the pyroelectric crystal 3 made of a chipped thin piece on the thermally insulating substrate 6.
It was difficult to handle and it was not possible to improve productivity. The present invention was made in consideration of the above circumstances, and its purpose is to provide a simple structure, easy handling, high sensitivity, durability, and reliability that can be expected to improve productivity. The purpose is to provide an excellent infrared detection bag layer.

That is, in the present invention, by integrally providing a pyroelectric crystal via a ground electrode on a semiconductor substrate having a hole in a portion facing a light-receiving electrode, the pyroelectric crystal can be easily handled, and the pyroelectric crystal can be made sufficiently thin. To provide an infrared detection device that improves detection sensitivity by using a semiconductor substrate with holes, prevents an increase in heat capacity by using a semiconductor substrate, and increases the reliability and durability of an element by applying the reliability and durability of a semiconductor substrate. It is something.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Figure 4 is a schematic diagram showing the general structure, and 11 in the figure is LITa.
It is a pyroelectric crystal consisting of 03 crystal.

This Atsushi Crystal 1 1 is, for example, 3.5 skins with a thickness of 50 Buddha meters x 3
．． It has a rectangular shape with a size of 5 fences, and a light receiving electrode 12 on the diameter 2 side is disposed on its upper surface. Further, on the back surface of the pyroelectric crystal 11, that is, on the opposite surface to the surface on which the light-receiving electrode 12 is formed, a ground electrode 13 is provided over the entire area. A silicon plate 15 serving as a semiconductor substrate is bonded to the surface of the exposed crystal 11 on which the ground electrode 13 is formed via a conductive adhesive 14 . Note that it is of course possible to use a semiconductor other than a silicon plate. This silicon plate 15 has a thickness of 250 mm with the (100) plane as the main surface.
It has a size of 3.5 ribs x 3.5 skins, and its center has an open area of 2.5 sails x 2.5 sails due to anisotropic etching.
Five holes 16 are bored. The entrance region of this hole 16 is opposite to the location where the light-receiving electrode 12 is formed. The pyroelectric crystal 11 provided with the legs made of the silicon plate 15 is bonded via a conductive adhesive 17 onto a mount 18 made of a metal cap or the like. This mount base 18 functions as a lead end of the ground electrode 13, and a lead device 20 is provided on the side thereof with an insulating material 19 interposed therebetween. A lead wire 21 made of metal or aluminum is connected to the first and second ends of the lead wire 21 to establish an electrical connection with the light receiving electrode 12. The size of the holes 16 provided in the silicon plate 15 is controlled by anisotropic etching using an etching agent such as hydrazine, as will be described in detail later. Thus, according to the above structure, the pyroelectric crystal 1
1 is thermally suspended from the mounting base 18 by the silicon plate 15, so that the same effect as a suspended structure can be obtained and an increase in the heat capacity can be prevented.

Moreover, since the ground electrode 13 is electrically connected to the mount 18 through the silicon plate 16 in an ohmic contact state, it is completely unnecessary to attach a lead wire to the ground electrode 13 using difficult manufacturing techniques as in the past. . It is also convenient to diffuse impurities into the silicon plate 15 in order to ensure the above-mentioned ohmic contact. In addition, Atsuka crystal 11 is
Since the structure is firmly fixed to the mount base 18 by the silicon plate 15, it has excellent durability and can be expected to dramatically improve its reliability. Furthermore, as will be explained later, since the Atsuden crystal 11 is integrally formed with the silicon plate 15, it is easy to process the thin plate, and the detection sensitivity can be improved.
Further, since only the thin fish electric crystal 11 is not handled, it is easy to manufacture, and mass production is possible, thereby improving the walking speed. Next, an example of the manufacturing process of this device having the above-mentioned foundation will be explained with reference to FIG.

First, as shown in FIG.
A ground electrode 13 is formed over the entire surface of the Z plate.

This ground electrode 13 is formed by, for example, a nichrome film by vapor deposition, sputtering, or the like. On the other hand, as shown in FIG. 5b, a silicon plate 1 having a thickness of 250 mm and an aperture on the 63 side and having an impurity concentration of 1 to 9-3 or more, for example, has a (100) plane.
An oxide film 23 is formed on one surface of the substrate 5. This oxide film 23 is patterned to provide each gate with an elevation angle of 2.8, which is used as a mask pattern for etching. Then, a conductive adhesive 14 is applied to the upper surface of the silicon plate 15, and the fifth
The pyroelectric crystal 11 shown in FIG. 5A is bonded onto the silicon plate 15 with the surface of its ground electrode 13 as the adhesive surface as shown in FIG. 5C. Thereafter, the surface of the pyroelectric crystal 11 is polished to a thickness of 50 m, as shown in FIG. 5d. Thereby, the thickness of the pyroelectric crystal 11 is set to a desired dimension to increase the infrared detection sensitivity. However, later, the pyroelectric crystal 11 and the silicon plate 1 forming the above-mentioned laminated integrated structure
5 was immersed in a hydrazine solution flooded with 100 qC. This etching agent made of hydrazine has a strong etching rate on the (100) plane and a slow etching rate on the (111) plane, which has direction dependence.
Therefore, the silicon plate 15 is anisotropically etched at an angle of about 57o with respect to its principal (100) plane. By this anisotropic etching, a hole 16 having an entrance size of 2.5 elevation angle is bored in the silicon plate 15 as shown in FIG. 5e. Thereafter, light-receiving electrodes 12 each having a thickness of 2.0 flea are arranged and formed on the upper surface of the pyroelectric crystal 11 at positions facing the holes 16 . When forming the light-receiving electrode 12, it goes without saying that it should be aligned with the hole 16 with high precision. However, hole 1
The exposed crystal (pyroelectric crystal 11 and silicon plate 15) after the formation of 6 and the patterning of the light-receiving electrode 12 has a planar structure as shown in FIG. Divide into.

Figure 5M shows one chip of pyroelectric crystal divided by dicing.As shown in Figure 5I, conductive adhesive 17 is applied to the back surface of the silicon plate 15, and this is
It is glued onto the mount stand 18 as shown in FIG. Then, the infrared detecting device is completed by attaching the lead wire 21 to the lead end 20 and the light receiving electrode 11 by bonding or the like. As described above, this device is extremely easy to manufacture because it can perform a series of manufacturing processes such as forming electrodes, polishing a thin plate of pyroelectric crystal, and etching a silicon plate while using a large-sized wafer.

Furthermore, devices of the same standard can be obtained in large quantities with good yield, resulting in extremely high productivity. Moreover, it can be easily manufactured using general-purpose manufacturing equipment. Note that the present invention is not limited only to the above embodiments.

For example, the dimensions of the pyroelectric crystal, silicon IJ board, etc. may be appropriately determined according to the specifications. Further, the hole-drilling process by multi-dimensional etching may be performed before adhering to the exposed crystal wafer.
Furthermore, triglycine sulfate, strongium, barium niobate, and PZ of ceramics are used as pyroelectric materials.
Of course, T, lead titanate, etc. can also be used. It goes without saying that the shape of the hole provided in the silicon plate is not particularly limited either. In short, the present invention can be implemented with various modifications without departing from the gist thereof. As detailed above, according to the present invention,
The thickness of the pyroelectric crystal can be made sufficiently thin to increase infrared detection sensitivity, and the suspended structure that is firmly held by the semiconductor substrate significantly improves durability and reliability, and its heat capacity is sufficiently low. It can be suppressed.

Further, it is possible to provide an infrared detection device that has a simple manufacturing process, is easy to handle, and can exhibit various extraordinary effects. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 3 are vague diagrams showing the structure of a conventional device, FIG. 4 is a schematic structural diagram showing an embodiment of the present invention, and FIGS. 5 a to j
1 is a diagram showing an example of a manufacturing process.

11... Pyroelectric crystal, 12... Light receiving electrode, 13... Ground electrode, 14, 17...
Conductive adhesive, 15... Silicon plate, 16... Hole, 18
...Mount stand, 19...Insulating material, 20...
- Lead end, 21... Lead wire, 23... Oxide film.

Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] 1. A pyroelectric crystal, a light-receiving electrode provided on the infrared-receiving surface of the pyroelectric crystal, a grounding electrode provided on the back surface opposite to the infrared-receiving surface of the pyroelectric crystal, and a ground electrode provided on the back surface of the pyroelectric crystal opposite to the infrared-receiving surface. An infrared detection device comprising: a semiconductor substrate bonded to an electrode via a conductive adhesive and having a hole bored in at least a region facing the light-receiving electrode. 2. The infrared detection device according to claim 1, wherein the semiconductor substrate is a silicon plate having a (100) plane as a main surface, and the holes are formed by anisotropic etching of the silicon plate. 3. The infrared detection device according to claim 1, wherein the opening area of the hole is set to be larger than the area of the light-receiving electrode.