JP4606014B2 - Thermopile infrared sensor - Google Patents

Description

  The present invention relates to an infrared sensor, and in particular, in a thermopile infrared sensor including an insulating membrane film having an infrared detection element and an appropriate pair of output terminal contact portions on the surface side of a silicon substrate, there is a risk of dielectric breakdown due to static electricity. The present invention relates to a thermopile type infrared sensor that eliminates the above.

  In general, a thermopile infrared sensor is housed in a container composed of a stem and a can, and an output terminal for taking out the output of the infrared detection element and a lead pin connected to the output terminal are provided so as to protrude out of the container. When the operator handles the thermopile type infrared sensor, if static electricity is generated by inadvertently touching the output terminal or the lead pin, the insulation state between the silicon substrate and the output terminal contact portion Is destroyed, and a short circuit occurs between the output terminals via the silicon substrate. The occurrence of dielectric breakdown due to static electricity is remarkable when a conductive film such as a polysilicon film doped with boron is present on the silicon substrate surface below the output terminal contact portion.

Conventionally, in the case of a thermopile infrared sensor provided with an insulating membrane film, an insulating membrane film is provided so as to reach the lower side of the output terminal contact portion to ensure insulation.
JP 2002-340668 A

  Usually, this insulating membrane film is made of silicon nitride, and its film thickness is about 1300 mm. However, it is difficult to avoid damage due to static electricity with a membrane film of this thickness, and to prevent dielectric breakdown. I could not. In particular, when a conductive film is provided with the insulating membrane film sandwiched below the output terminal contact portion, the insulating membrane film is easily damaged. For this reason, in the past, reliable insulation between the output terminal contact portion and the silicon substrate surface could not be guaranteed. It is an object of the present invention to provide an infrared sensor that eliminates such conventional disadvantages and reliably ensures insulation between the output terminal contact portion and the silicon substrate surface.

To this end, the thermopile-type infrared sensor according to claim 1 of the present invention, the silicon substrate surface side, the first of definitive infrared detection element to the infrared detection element and the insulating membrane film formed thereon comprising a by conductive polysilicon film and electrodes to form a hot junction and an output terminal contact portions of the appropriate pair of connections, the silicon substrate surface side to the silicon substrate from the insulating membrane film under the infrared detection element down with the thermopile-type infrared sensor having an apertured cavity thickness provided a silicon oxide insulating film at least 4000Å between the silicon substrate surface on the outside of the cavity and the output terminal contact portions, the opening of the cavity between the insulating membrane film and the silicon substrate surface to outer edge, a second conductive Without providing the silicon oxide insulating film is provided a polysilicon film, and the end portion of the silicon oxide insulating film away from the opening end of the cavity, the said infrared detection element, the first conductive poly A coating film is provided to cover the silicon film except for the output terminal contact portion and the electrode, and the output terminal contact portion is provided on the outer edge of the opening end of the cavity above the silicon oxide insulating film. The second conductive polysilicon film is provided at a position not corresponding to the second conductive polysilicon film. The film thickness of the silicon oxide insulating film is preferably in the range of 4000 to 10,000 mm in order to prevent damage due to static electricity and to ensure ease of manufacture.

Also in order to achieve the above object, the thermopile-type infrared sensor according to claim 2 of the present invention, the silicon substrate surface side, a definitive and insulating membrane film forming an infrared detecting element thereon on the infrared detector and an output terminal contact portions of the appropriate pair by one of the conductive polysilicon film and connecting electrodes to form a hot junction, the silicon substrate toward the silicon substrate from the insulating membrane film under the infrared detection element down in the thermopile-type infrared sensor having an apertured cavity surface, Rutotomoni provided a silicon oxide insulating film having a thickness on the silicon substrate surface on the outside of said cavity at least 4000 Å, wherein the opening edge of the cavity A second conductive polysilicon film is provided between the silicon substrate surface and the insulating membrane film. Without providing the silicon oxide insulating film, the end portion of the silicon oxide insulating film and away from the opening end of the cavity, the said infrared detection element, said first conductive polysilicon film, the output A coating film for covering is provided except for the terminal contact portion and the electrode, and the second conductive polymer is provided on the outer edge of the opening of the cavity above the silicon oxide insulating film. The insulating membrane film is extended between the output terminal contact portion and the silicon oxide insulating film to a position corresponding to the lower portion of the output terminal contact portion. The insulating membrane film has a film thickness of about 1300 mm, for example. The film thickness of the insulating membrane film may be the same as that of the prior art due to the presence of the silicon oxide insulating film, and it is not necessary to form the insulating membrane film much thicker.

Also in order to achieve the above object, the thermopile-type infrared sensor according to claim 3 of the present invention, the silicon substrate surface side, a definitive and insulating membrane film forming an infrared detecting element thereon on the infrared detector and an output terminal contact portions of the appropriate pair by one of the conductive polysilicon film and connecting electrodes to form a hot junction, the silicon substrate toward the silicon substrate from the insulating membrane film under the infrared detection element down in the thermopile-type infrared sensor having a cavity which is open on the front side, so as to be positioned between the silicon substrate surface and the output terminal contact portion on the outside of the cavity, the thickness on the silicon substrate surface at least 4000Å , preferably provided with a silicon oxide insulating film 4000~10000Å Rutotomoni, said cavity A second conductive polysilicon film is provided between the silicon substrate surface and the insulating membrane film at the outer edge of the opening, and the end of the silicon oxide insulating film is formed without providing the silicon oxide insulating film. The infrared detection element is provided with a coating film that covers the first conductive polysilicon film except for the output terminal contact part and the electrode. An output terminal contact portion is provided above the silicon oxide insulating film at a position not corresponding to the second conductive polysilicon film provided at the outer edge of the opening of the cavity, and the output terminal contact portion An insulating membrane film having a film thickness of, for example, about 1300 mm is extended between the silicon oxide insulating film and a position corresponding to the lower portion of the output terminal contact portion. The between the insulating membrane film and the silicon oxide insulating film, and a position corresponding to the lower output terminal contact portions, for example, it is provided with a polysilicon insulating film having a thickness of about 4000 Å.

  According to the thermopile type infrared sensor of claim 1 of the present invention, a silicon oxide insulating film having a film thickness of at least 4000 mm exists on the surface of the silicon substrate corresponding to the lower portion of the output terminal contact portion, and the silicon oxide Since there is no possibility of damage to the insulating film due to static electricity, there is an effect that it is possible to avoid a short circuit between the output terminals via the silicon substrate.

  According to the thermopile type infrared sensor of claim 2 of the present invention, an insulating membrane film is interposed between the silicon substrate surface and the output terminal contact portion in addition to the silicon oxide insulating film having a thickness of at least 4000 mm. Therefore, both of these two insulating films are not damaged by static electricity, and it is possible to more reliably avoid a short circuit between the output terminals via the silicon substrate.

  According to the thermopile type infrared sensor of the third aspect of the present invention, three insulating films of a silicon oxide insulating film, an insulating membrane film, and a polysilicon insulating film are interposed between the surface of the silicon substrate and the output terminal contact portion. As a result, the three insulating films are not damaged by static electricity, and the short circuit between the terminals via the silicon substrate can be more reliably avoided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. First, a first embodiment will be described with reference to FIG. 1 which is a schematic end view of a thermopile infrared sensor. As shown in FIG. 1, the silicon substrate 1 is provided with a cavity 2 and a conductive polysilicon film 4 doped with boron, which is a second conductive polysilicon film, around the cavity 2, and this conductivity is provided. A silicon oxide insulating film 3 having a thickness of 4000 mm is provided around the polysilicon film 4 and the inner edge of the silicon oxide insulating film 3 is formed in the shape of a bird's beak. It is piled up so as to dive under.

An insulating membrane film 5 having a thickness of about 1300 mm made of silicon nitride is provided so as to cover the conductive polysilicon film 4 and the cavity 2, and a region surrounded by the conductive polysilicon film 4 is formed. It becomes the membrane area. An infrared detection element is provided on the insulating membrane film 5. That is, a conductive polysilicon film 8 that is a first conductive polysilicon film connected to the output terminal contact portion 6 and the aluminum electrode 7 that forms the hot junction is provided, and the output terminal contact portion 6 and the aluminum electrode 7 are provided. Is covered with a silicon oxide coating film 9, and a plasma silicon oxide layer 10 and a plasma silicon nitride layer 11 are sequentially stacked on the coating film 9, and further positioned above the membrane region. An amorphous silicon film 12 and a heat absorption film 13 are provided.

  The output terminal contact portion 6 is located above the silicon oxide insulating film 3 and is not located above and below the conductive polysilicon film 4. Although only one output terminal contact portion 6 is shown, a pair of a plus output terminal and a minus output terminal is provided, and when the infrared sensor is accommodated in a container not shown as in the prior art. These output terminals are electrically connected to lead pins (not shown). In FIG. 1, 14 is an etching hole, and 15 is a pad opening. The cavity 2 is formed by etching from the etching hole 14. At that time, the conductive polysilicon film 4 serves as an etching stopper, and a predetermined region surrounded by the conductive polysilicon film 4 serves as a membrane region.

Since the first embodiment is configured as described above, the silicon oxide insulating film 3 having a thickness of 4000 mm is interposed between the surface of the silicon substrate 1 and the output terminal contact portion 6, and the silicon oxide insulating film 3 is sufficient. Since it has a thickness, there is no possibility of being damaged by static electricity, coupled with the absence of another conductive member between the surface of the silicon substrate 1. Thereby, a short circuit between the output terminals via the silicon substrate 1 can be avoided. Further, the output terminal contact portion 6 since the conductive polysilicon film 4 is in a position that does not correspond to the top and bottom, avoiding the short is more reliably ensured. Since the operation as a thermopile type infrared sensor is the same as the conventional one, its description is omitted.

  Next, 2nd Embodiment of this invention is described based on FIG. 2 which is a schematic end view of a thermopile type infrared sensor. As shown in FIG. 2, the difference in configuration between the present embodiment and the first embodiment described above is that a part of the insulating membrane film 25 is extended, and this extended portion 25a is oxidized with the output terminal contact portion 26. The only difference is that the corresponding positions are provided between the silicon insulating films 23, and the other configurations are the same as those in the first embodiment. Is omitted.

  Since the second embodiment is configured as described above, the two insulating films, that is, the silicon oxide insulating film 23 and the insulating membrane film 25 interposed between the surface of the silicon substrate 1 and the output terminal contact portion 26, are both caused by static electricity. Since there is no risk of breakage, a short circuit between the output terminals through the silicon substrate 1 can be avoided, and the output terminal contact portion 26 is in a position that does not correspond to the conductive polysilicon film 4 in the vertical direction. Therefore, the avoidance of the short circuit is more reliably guaranteed. In the second embodiment, the operation as the thermopile type infrared sensor is the same as the conventional one, and the description thereof is omitted.

Next, a third embodiment of the present invention will be described based on FIG. 3 which is a schematic end view of a thermopile type infrared sensor. As shown in FIG. 3, the difference in configuration between the present embodiment and the second embodiment described above is that the output terminal contact portion 36 is provided between the extended portion 35 a side of the insulating membrane film 35 and the silicon oxide insulating film 33. The polysilicon insulating film 30 having a thickness of 4000 mm is arranged in parallel with a part of the conductive polysilicon film 34 doped with boron, and the other configuration is as follows. Since it is the same as the structure of 2nd Embodiment, it attaches | subjects the same code | symbol to a corresponding component, and abbreviate | omits detailed description.

Since the third embodiment is configured as described above, the three insulations of the silicon oxide insulating film 33, the insulating membrane film 35, and the polysilicon insulating film 30 interposed between the surface of the silicon substrate 1 and the output terminal contact portion 36 are provided. film, since fear will not damage all by static electricity, the silicon substrate 1 can avoid short circuit between the output terminals through, also, the output terminal contact portion 36 is offset from the conductive polysilicon film 34 Therefore, avoidance of the short circuit is more reliably ensured. In the third embodiment, the operation as a thermopile type infrared sensor is the same as the conventional one, and the description thereof is omitted.

  If the output terminal contact portions 6, 26, and 36 are formed so as to have a larger plane area than those conventionally used, the function of ensuring insulation when static electricity is generated increases. Further, the configuration of the films 9, 10, 11, 12, and 13 stacked on the insulating membrane films 5, 25, and 35 is not limited to the above-described embodiment, and can be appropriately changed.

1 is a schematic end view of a thermopile type infrared sensor showing a first embodiment. FIG. The schematic end elevation of the thermopile type infrared sensor which shows 2nd Embodiment. The schematic end elevation of the thermopile type infrared sensor which shows 3rd Embodiment.

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Cavity 3,23,33 Silicon oxide insulating film 4,34 Conductive polysilicon film 5,25,35 Insulating membrane film 6,26,36 Output terminal contact part 7 Aluminum electrode 8 Conductive polysilicon film 25a , 35a Extension part 30 Polysilicon insulating film

Claims (3)

On the silicon substrate surface side, appropriate pair of output terminals to connect the electrode to form a hot junction with the first conductive polysilicon film definitive an insulating membrane film forming an infrared detecting element thereon on the infrared detector A thermopile type infrared sensor comprising a contact portion, and having a cavity opened on the silicon substrate surface side from under the insulating membrane film below the infrared detection element into the silicon substrate;
A silicon oxide insulating film having a film thickness of at least 4000 mm is provided between the silicon substrate surface and the output terminal contact portion outside the cavity, and the silicon substrate surface and the insulating property are provided at the outer edge of the opening of the cavity . Without providing the silicon oxide insulating film by providing a second conductive polysilicon film between the membrane film, the end of the silicon oxide insulating film is separated from the opening end of the cavity,
The infrared detection element is provided with a coating film that covers the first conductive polysilicon film except for the output contact portion and the electrode,
The thermopile is characterized in that the output terminal contact portion is provided above the silicon oxide insulating film at a position not corresponding to the second conductive polysilicon film provided at the outer edge of the opening of the cavity. Type infrared sensor.   2. The thermopile infrared sensor according to claim 1, wherein an insulating membrane film is extended between the output terminal contact portion and the silicon oxide insulating film to a position corresponding to the lower portion of the output terminal contact portion.   3. A thermopile infrared sensor according to claim 2, wherein a polysilicon insulating film is provided between the insulating membrane film and the silicon oxide insulating film so as to correspond to a position below the output terminal contact portion.

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