Fishing – trapping – and vermin destroying
Patent
1994-05-17
1996-12-10
Thomas, Tom
Fishing, trapping, and vermin destroying
2503384, H01L 2714, G01J 502
Patent
active
055830587
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to an infrared detecting element array utilizing electrical characteristics varied by heat such as pyroelectricity, an electric resistance varied according to temperature and thermoelectromotive force, and to a method for fabricating such infrared detecting element array. More particularly, it relates to a highly integrated infrared detecting element array with less crosstalk having a two-dimensional structure of infrared detecting elements of which temperature rises easily with less heat and to a method for fabricating the same.
2. Background Art
Conventional infrared detecting devices are categorized as photo-detectors and thermal detectors. The photo-detectors assure high precision and high responsiveness and allows the size thereof to be scaled down since they are capable of employing detecting elements each reduced in size. However, the photo-detectors need to be cooled down to a temperature lower than 0.degree. C. and hence suffer a drawback of costly running when in use. The thermal detectors are less sensitive and less responsive than the photo-detectors but offer an advantage that cooling is unnecessary. The thermal detectors include pyroelectric type, capacitor type (driven with alternating current), resistor type and thermoelectromotive force type. Technical objectives common to the thermal detectors are: rise caused by infrared rays; operation (to reduce crosstalk) in order to obtain a clear image; amplification, signal processing or the like; integrated into a package or the like.
Among the thermal detectors, the pyroelectric type detector has a relatively high sensitivity. Pyroelectric type detectors in the form of array which have so far been put into practice are fabricated by defining grooves on a thin wafer of pyroelectric ceramic or by cutting such wafer into small pieces and arranging them in an array. For example, one disclosed in Bulletin of Ceramic Process, No. 41, 1989, pp. 205-217 is of a configuration formed by defining grooves into a pyroelectric ceramic wafer to form a chip, providing an infrared absorption layer on the chip and forming electrodes on the lower side of the chip. This configuration is characterized in that the detector is soldered to a silicon multiplexer by the pad provided on each lower electrode.
Such configuration, however, involves disadvantages such as: ceramic wafer; thermal expansion coefficient between the ceramic and the silicon used for the multiplexer;
An approach being considered to reduce the heat capacity is to employ a thin film for forming infrared detecting elements. Japanese Unexamined Patent Publication No. 129677/1988 discloses a structure wherein a film having pyroelectric elements arranged is held by an MgO substrate at both ends thereof. Method of forming this structure includes forming a pyroelectric thin film on a single-crystalline MgO substrate, forming a multiplicity of separate thin metal electrode films on the pyroelectric thin film, and partially removing the portion of the substrate in contact with the pyroelectric film to leave the pyroelectric film bridging over the removed portion. However, such a structure wherein the substrate is etched in a portion under the pyroelectric film to hold the pyroelectric film is poor in strength. Japanese Unexamined Patent Publication No. 94227/1989 discloses an art of cutting a through-hole into a semiconductor substrate from the lower side thereof. With this method, however, the use of a p-type silicon substrate makes it impossible to etch anisotropically from the lower side of the substrate to have a directionality. Hence, isotropic etching must be effected, resulting in a problem of a large etched region extending even under the mask defining an opening for etching. Japanese Unexamined Patent Publication No. 136038/1989 discloses a method including defining a groove into a substrate, filling the groove with spacer, forming a supporting film and forming on the supporting film a pyroelectric film. This method, however, has a disadvan
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Okumura Masatomi
Sakai Yuichi
Sato Ken
Sato Takehiko
Utsumi Yoshikazu
Mitsubishi Denki & Kabushiki Kaisha
Mulpuri S.
Thomas Tom
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